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Zeitschriftenartikel zum Thema „Crystal defect analysis“

Autor: Grafiati

Veröffentlicht am 1. Dezember 2023

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1

Kirste, Lutz, Karolina Grabianska, Robert Kucharski, Tomasz Sochacki, Boleslaw Lucznik und Michal Bockowski. „Structural Analysis of Low Defect Ammonothermally Grown GaN Wafers by Borrmann Effect X-ray Topography“. Materials 14, Nr. 19 (22.09.2021): 5472. http://dx.doi.org/10.3390/ma14195472.

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X-ray topography defect analysis of entire 1.8-inch GaN substrates, using the Borrmann effect, is presented in this paper. The GaN wafers were grown by the ammonothermal method. Borrmann effect topography of anomalous transmission could be applied due to the low defect density of the substrates. It was possible to trace the process and growth history of the GaN crystals in detail from their defect pattern imaged. Microscopic defects such as threading dislocations, but also macroscopic defects, for example dislocation clusters due to preparation insufficiency, traces of facet formation, growth bands, dislocation walls and dislocation bundles, were detected. Influences of seed crystal preparation and process parameters of crystal growth on the formation of the defects are discussed.

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2

Mohammed, M., und W. Cel. „Photonic crystal analysis for multiplexer and de-multiplexer applications“. Journal of Physics: Conference Series 2322, Nr. 1 (01.08.2022): 012074. http://dx.doi.org/10.1088/1742-6596/2322/1/012074.

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Abstract In our present work, we have made an investigation of several theoretical tools using the finite element method depending on the COMSOL MULTIPHYSICS program, for intuitive insight into the optical properties of the optical crystal. Analysis of the bandgap of a two-dimensional periodic photonic crystal with square lattice, evaluate the photonic band structure by the eigenfrequency of the unit cell of the first Brillouin zone. Moreover, creating defect mode inside the bandgap of photonic crystal, such as a resonant cavity, waveguide defect, narrowband filter, sharp drop filter, channel drop filter, waveguide bends, waveguide splitter promises us to a platform to design devices that includes a certain optical range of wavelengths. The transmission, as a result, the influence of the light localized in the defect area of the periodic structure of the photonic crystal. This study is important for producing photonic integrated circuits based on photonic crystals for future advanced optical communication.

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3

Wang, Ke, Ren Ke Kang, Zhu Ji Jin und Dong Ming Guo. „Theoretical Analysis and Experimental Verification of Triangular Fracture Defects of MgO Single Crystal Substrate in Lapping or Polishing Process“. Key Engineering Materials 364-366 (Dezember 2007): 739–44. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.739.

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MgO single crystal is mainly used as substrate for high temperature superconductor film. Surface quality of MgO substrate has significant effect on the function of high temperature superconductor film. MgO single crystal is a typical hard and brittle material, and is easily cleaved along the {100} face, so some defects are always generated on the substrate surface while lapping and polishing, which badly affects the surface quality of the substrate. In this paper, a kind of typical defect, the triangular fracture defect which is on the substrate surface after lapping and polishing, is analyzed in detail. According to the structure characteristics of the MgO single crystal, and based on the dislocation reaction theory, a formation mechanism of the triangular fracture defect in lapping and polishing processes is explored. Through the single grain scratch test in different directions on the polished surface of MgO{100} single crystal substrates, the formation mechanism of triangular fracture defect in lapping and polishing processes is verified. And during the scratch test, the plastic flow of the MgO single crystal material beside the scratch was observed.

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4

Larson, Bennett C. „Historical Perspective on Diffraction Line-Profile Analyses for Crystals Containing Defect Clusters“. Crystals 9, Nr. 5 (17.05.2019): 257. http://dx.doi.org/10.3390/cryst9050257.

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Deviations of crystal diffraction line profiles from those predicted by the dynamical theory of diffraction for perfect crystals provide a window into the microscopic distributions of defects within non-perfect crystals. This overview provides a perspective on key theoretical, computational, and experimental developments associated with the analysis of diffraction line profiles for crystals containing statistical distributions of point defect clusters, e.g., dislocation loops, precipitates, and stacking fault tetrahedra. Pivotal theoretical developments beginning in the 1940s are recalled and discussed in terms of their impact on the direction of theoretical and experimental investigations of lattice defects in the 1960s, the 1970s, and beyond, as both experimental and computational capabilities advanced. The evolution of experimental measurements and analysis techniques, as stimulated by theoretical and computational progress in understanding the distortion fields surrounding defect clusters, is discussed. In particular, consideration is given to determining dislocation loop densities and separate size distributions for vacancy and interstitial type loops, and to the internal strain and size distributions for coherent precipitates.

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5

Kato, Tomohisa, Kazutoshi Kojima, Shin Ichi Nishizawa und Kazuo Arai. „Defect Characterization of 4H-SiC Bulk Crystals Grown on Micropipe Filled Seed Crystals“. Materials Science Forum 483-485 (Mai 2005): 315–18. http://dx.doi.org/10.4028/www.scientific.net/msf.483-485.315.

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We report defects study in 4H-SiC bulk crystals grown by sublimation method on micropipe filled seed crystals oriented (0001) on-axis. The seed crystals of 1~3 inch in diameter were prepared from the large 4H-SiC bulk crystals. Before the sublimation growth, micropipes of the seed crystals were filled with epilayers grown by micropipe filling technique of CVD method. We confirmed about 95% of micropipes perfectly disappeared in the grown crystal. The mechanism of the micropipe extinction was also defined by defect analysis.

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6

Chikvaidze, G., N. Mironova-Ulmane, A. Plaude und O. Sergeev. „Investigation of Silicon Carbide Polytypes by Raman Spectroscopy“. Latvian Journal of Physics and Technical Sciences 51, Nr. 3 (01.06.2014): 51–57. http://dx.doi.org/10.2478/lpts-2014-0019.

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Abstract Polytypes of colourless and coloured single crystals of silicon carbide (SiC) grown on SiC substrates by chemical vapour deposition are studied using Raman spectroscopy supplemented by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The SEM analysis of the defect stacking faults, inclusions of defects and their distribution has shown that they correlate with the peak positions of the obtained Raman spectra and with the XRD data on the crystal structure

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7

Katch, L., M. Moghaddaszadeh, C. L. Willey, A. T. Juhl, M. Nouh und A. P. Argüelles. „Analysis of geometric defects in square locally resonant phononic crystals: A comparative study of modeling approaches“. Journal of the Acoustical Society of America 154, Nr. 5 (01.11.2023): 3052–61. http://dx.doi.org/10.1121/10.0022330.

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Phononic crystals can develop defects during manufacturing that alter the desired dynamic response and bandgap behavior. This frequency behavior change can enable successful defect inspection if the characteristic defect response is known. In this study, the behavior of a defective square unit cell comprising a freed and shortened leg is studied using a wave finite element method and an approximate continuous-lumped model to elucidate the defect induced qualitative dynamical features. These metrics are a computationally inexpensive alternative to modeling a defective unit cell within a large pristine array entirely in finite elements. The accuracy of these models is validated by comparing the result to a full finite element model. The impact of a shortened unit cell leg on the behaviors of an infinite array of defective cells and a finite array with a single defect are successfully predicted through dispersion curves and frequency response functions, respectively. These methods reveal defect-induced modes that split the local resonance bandgap of the pristine cell, as well as new anti-resonances resulting from the shortened leg. The study uses both approaches to evaluate the effect of defects in complex phononic crystal geometries and provides a comparative evaluation of the results of each model.

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8

Nykyruy, L. I., V. V. Prokopiv, M. P. Levkun und A. V. Lysak. „Analysis of Defect Subsystem ZnSe, Doped with Transition Metals (Co, Ni)“. Фізика і хімія твердого тіла 16, Nr. 4 (15.12.2015): 716–21. http://dx.doi.org/10.15330/pcss.16.4.716-721.

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The crystal-quasichemical formulae of doping at the Crystals n-ZnSе:Cо(Ni) аnd p-ZnSе:Cо(Ni) are suggested. The dependence on point defects concentration, on free chargecarrier concentration and Hall concentration of the degree of nonstoichiometry (α, β) are calculated.

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9

Al-Sharab, Jafar F., S. D. Tse und B. H. Kear. „Defect Analysis of Single Crystal Synthetic Diamond“. Microscopy and Microanalysis 24, S1 (August 2018): 1766–67. http://dx.doi.org/10.1017/s1431927618009315.

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10

Song, Pingxin, Zhiwei Zhao, Xiaodong Xu, Peizhen Deng und Jun Xu. „Defect analysis in Czochralski-grown Yb:FAP crystal“. Journal of Crystal Growth 286, Nr. 2 (Januar 2006): 498–501. http://dx.doi.org/10.1016/j.jcrysgro.2005.10.116.

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11

Yeh, Jia Yi. „The Design and Analysis of Topological Phononic Crystals with Cavity“. Key Engineering Materials 963 (13.10.2023): 47–52. http://dx.doi.org/10.4028/p-fo9zp7.

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The topological phononic crystal is composed of two topologically distinct structures. The topological phononic crystal resonant cavity based are proposed and the acoustic wave propagate characteristics are also presented. The topological cavity with defects will change the resonance frequency and quality factor is also discussed. The advantages of the topological cavity are the better quality factors and the concentrated sound pressure larger than general defect cavity.

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12

Sidorov, N. V., A. V. Kadetova, M. V. Smirnov, R. A. Titov, N. A. Teplyakova und M. N. Palatnikov. „Features of the defect structure and photoluminescence of nominally pure LiNbO3 crystals grown from boron doped charge“. Perspektivnye Materialy 2 (2023): 32–43. http://dx.doi.org/10.30791/1028-978x-2023-2-32-43.

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Features of the defect structure of nominally pure LiNbO3:В crystals were investigated by X-ray diffraction analysis and photoluminescence. Crystals were grown by the Czochralski from a mixture of congruent composition charge containing 0.08 and 0.12 wt. % boron. At this, the concentration of boron in crystals is at the level of trace amounts of metallic impurities and is ~ 10–4 wt%. MeO6 oxygen-octahedral clusters are responsible for the ferroelectric and nonlinear optical properties of the crystal. It has been found that in LiNbO3:B crystals, the lengths of O–O, Me–O, and Me–Me (Me–Li, Nb) bonds in clusters, the arrangement of Me cations, vacancies, and NbLi point defects along the polar axis differ significantly from those for nominally pure congruent crystal. NbLi defects and transition metals are deep electron traps responsible for the photorefraction effect. The photoluminescence spectra showed that the concentration of defects and metals in the investigated LiNbO3:B crystals is lower than in the congruent crystal. these differences can be due to both a change in the properties of the boron-containing melt and the localization of trace amounts of boron in the O4 tetrahedral gaps of the LiNbO3 crystal structure. In the first case, reactive boron binds cations of niobium and transition metals in the melt into stable complexes.

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13

Barry, J. C., und E. F. Bres. „HRTEM of hydroxyapatite in carious human tooth enamel“. Proceedings, annual meeting, Electron Microscopy Society of America 45 (August 1987): 170–71. http://dx.doi.org/10.1017/s0424820100125786.

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Human dental enamel is composed 98% by weight of small, densely packed carbonated hydroxyapatite (HAP) crystals. These crystals have an unusual morphology and often contain a “central dark line” (CDL) defect. The HAP crystals in carious enamel are preferentially dissolved at the CDL defect. Bres et al. have identified three types of disorder in human tooth enamel crystallites near to the crystal midline: a) regions of lattice buckling and departure from hexagonal symmetry, b) dislocations and c) grain and twin boundaries. Nelson et al. have obtained very clear images of planar defects, similar to the CDL defects in human enamel, at the centers of crystals of certain synthetic carbonated apatites. In this present study HRTEM images have been obtained from carious regions of tooth enamel, and an analysis of the results is attemped in the light of previous work.

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14

Kosmidou, Elissavet P., Emmanouil E. Kriezis und Theodoros D. Tsiboukis. „FDTD analysis of photonic crystal defect layers filled with liquid crystals“. Optical and Quantum Electronics 37, Nr. 1-3 (Januar 2005): 149–60. http://dx.doi.org/10.1007/s11082-005-1132-5.

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15

Tanaka, Michiyoshi. „The large angle technique and lattice defect identifications“. Acta Crystallographica Section A Foundations and Advances 70, a1 (05.08.2014): C40. http://dx.doi.org/10.1107/s2053273314099598.

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The history of the Convergent Beam Electron Diffraction (CBED) is shortly introduced. Symmetry determinations[1] of crystals or the point groups and space groups of 3, 4, 5 and 6 dimensional crystals, and crystal structure analysis including the determination of charge density distribution and potential distribution of a crystal are briefly reviewed.[2] Then, the large angle CBED (LACBED) technique is described.[3] Applications of the LACBED technique to the determinations of the Burgers vector of a dislocation, the shift vector at a stacking fault, the precise orientation difference of a twin domain and the strain of an advanced multi-layer material are reviewed.

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16

Malinowska, Agnieszka, Maria Lefeld-Sosnowska und Jürgen Härtwig. „Contrast in transmission X-ray diffraction topographs of growth defects in the core of SrLaGaO4single crystals“. Journal of Applied Crystallography 46, Nr. 1 (17.01.2013): 48–54. http://dx.doi.org/10.1107/s0021889812050522.

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Defects in the core of SrLaGaO4single crystals, grown by the Czochralski method using a [001]-oriented seed, were studied by transmission X-ray diffraction projection topography. Topographs were taken with radiation from a laboratory source and with high-energy radiation available at the ESRF beamline ID19 in Grenoble. The contrast of the investigated defect images was analysed for various diffraction vectorsgand for various values of the product μ0t(μ0is the linear absorption coefficient andtthe crystal thickness). This allowed the contrast formation to be studied as a function of absorption. The results of the analysis confirm the model of crystal lattice deformation around rod-like volume defects in SrLaGaO4crystals.

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17

Chen, Jun, Ronit R. Prakash, Jian Yong Li, Karolin Jiptner, Yoshiji Miyamura, Hirofumi Harada, Atsushi Ogura und Takashi Sekiguchi. „Analysis of Inhomogeneous Dislocation Distribution in Multicrystalline Si“. Solid State Phenomena 205-206 (Oktober 2013): 77–82. http://dx.doi.org/10.4028/www.scientific.net/ssp.205-206.77.

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Grain boundaries and dislocations are major crystallographic defects in multicrystalline Si materials for solar cells. Heavily dislocated grains are detrimental to the photovoltaic performance. This paper attempts to clarify the origin of inhomogeneous defect distribution in multicrystalline Si. The impacts of crystal orientation and grain boundary were investigated. The crystal orientation gives an important geometrical effect in the possibility of initiating slip in a grain when subjected to stress. The presence of grain boundary can also affect dislocation distribution depending on boundary character.

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18

Yu, Dongling, Huiling Zhang, Jiaqi Yi, Yongzhen Fang und Nanxing Wu. „Dislocation Analysis of 3C-SiC Nanoindentation with Different Crystal Plane Groups Based on Molecular Dynamics Simulation“. Journal of Nanomaterials 2021 (15.12.2021): 1–11. http://dx.doi.org/10.1155/2021/2183326.

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To explore the deformation law of nanoindentation dislocations of different crystal plane groups of 3C-SiC by cube indenter. The molecular dynamics simulation method is used to construct the different crystal plane family models of 3C-SiC, select the ensemble, set the potential function, optimize the crystal structure, and relax the indentation process. The radial distribution function, shear strain, and dislocation deformation of nanoindentation on (001), (110), and (111) planes were analyzed, respectively. In the radial distribution function, the change in g r in the (110) crystal plane is the most obvious. Shear strain and dislocation occur easily at the boundary of square indentation defects. During the indentation process, the shear strain is enhanced along the atomic bond arrangement structure, (001) crystal plane shear strain is mainly concentrated around and below the indentation defects and produce a large number of cross dislocations, (110) the crystal plane shear strain is mainly concentrated in the shear strain chain extending around and below the indentation defect, which mainly produces horizontal dislocations, and (111) the crystal plane shear strain is mainly concentrated in four weeks extending on the left and right sides in the direction below the indentation defect and produces horizontal and vertical dislocations. The direction of shear stress release is related to the crystal structure. The crystal structure affects the direction of atomic slip, resulting in the results of sliding in different directions. The final dislocation rings are different, resulting in different indentation results.

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19

Antuzevics, A., A. Fedotovs und U. Rogulis. „Epr Spectrum Angular Dependences In Liyf4 Crystal / Epr Spektru Leņķiskās Atkarības Liyf4 Kristālā“. Latvian Journal of Physics and Technical Sciences 49, Nr. 6-I (01.12.2012): 49–54. http://dx.doi.org/10.2478/v10047-012-0034-0.

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Abstract Electron paramagnetic resonance (EPR) measurements have been made for two perpendicular planes in a LiYF4 crystal before and after x-ray irradiation at room temperature. Analysis of the EPR spectrum angular dependence shows the presence of two defects - an impurity ion, which was embedded during the crystal growth process, and an x-ray induced defect with the g-factor of approx. 2.0. Spectral parameters and possible defect models are discussed.

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Shi, Jian Ping, Yuan Huang und Song Ling Wen. „Multi-Channels PCs Polarization Filter and Analysis of Influence Factors“. Key Engineering Materials 428-429 (Januar 2010): 519–23. http://dx.doi.org/10.4028/www.scientific.net/kem.428-429.519.

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We present a multi-channel PCs polarization filter, which overcomes the disadvantage of the low channel numbers in the existing filters. The multi-channel PCs polarization filter is based on one dimensional photonic crystal with a defect layer. The simulation results by transfer matrix method show that the filter can realize more than four filtering channels with the separation degree better than 0.95 and the transmission rate more than 50%, and the channels are almost distributed evenly. We also analyze the influence factors of filter performance. The results show that defect layer thickness of photonic crystal determines the number of filter channels. The thickness and number of unit layers of photonic crystals does not affect the number of filter channels, however it can adjust the location of central wavelength for each filter channel.

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21

Gao, Jiang-Dong, Jian-Li Zhang, Xin Zhu, Xiao-Ming Wu, Chun-Lan Mo, Shuan Pan, Jun-Lin Liu und Feng-Yi Jiang. „Detailed surface analysis of V-defects in GaN films on patterned silicon(111) substrates by metal–organic chemical vapour deposition“. Journal of Applied Crystallography 52, Nr. 3 (31.05.2019): 637–42. http://dx.doi.org/10.1107/s1600576719005521.

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The growth mechanism of V-defects in GaN films was investigated. It was observed that the crystal faces of both the sidewall of a V-defect and the sidewall of the GaN film boundary belong to the same plane family of \{ {{{10\bar 11}}} \}, which suggests that the formation of the V-defect is a direct consequence of spontaneous growth like that of the boundary facet. However, the growth rate of the V-defect sidewall is much faster than that of the boundary facet when the V-defect is filling up, implying that lateral growth of \{ {{{10\bar 11}}} \} planes is not the direct cause of the change in size of V-defects. Since V-defects originate from dislocations, an idea was proposed to correlate the growth of V-defects with the presence of dislocations. Specifically, the change in size of the V-defect is determined by the growth rate around dislocations and the growth rate around dislocations is determined by the growth conditions.

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Liu, Chi-Chung, und Chien-Jang Wu. „Analysis of defect mode in a dielectric photonic crystal containing ITO defect“. Optik 125, Nr. 24 (Dezember 2014): 7140–42. http://dx.doi.org/10.1016/j.ijleo.2014.07.120.

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23

Xue, Weiqi, Luisa Ottaviano, Yaohui Chen, Elizaveta Semenova, Yi Yu, Alexandra Lupi, Jesper Mork und Kresten Yvind. „Thermal analysis of line-defect photonic crystal lasers“. Optics Express 23, Nr. 14 (06.07.2015): 18277. http://dx.doi.org/10.1364/oe.23.018277.

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24

Kato, Tomohisa, Tomonori Miura, Keisuke Wada, Eiji Hozomi, Hiroyoshi Taniguchi, Shin Ichi Nishizawa und Kazuo Arai. „Defect and Growth Analysis of SiC Bulk Single Crystals with High Nitrogen Doping“. Materials Science Forum 556-557 (September 2007): 239–42. http://dx.doi.org/10.4028/www.scientific.net/msf.556-557.239.

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In this study, we report defect analysis in 4H-SiC crystals of high nitrogen doping grown by sublimation method, and we discuss key points for defect restraint. The growth was performed in two kinds of growth directions; c-axis and a-axis. In the c-axis grown crystal with carrier density greater than 1×10-19cm-3, defect propagation was confirmed in the vertical direction for a growth direction affected by the doping by x-ray topography. This phenomenon was not observed in the a-axis grown crystals. In sublimation growth, the quantity of impurities tends to increase as growth rate decreases. Therefore, in the c-axis growth of doped 4H-SiC bulk crystals, we have to be careful so that dopant does not increase too much without intention in grown layers with lower growth rate, for example at the beginning and end of the growth.

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Mugnaioli, Enrico, und Tatiana E. Gorelik. „Structure analysis of materials at the order–disorder borderline using three-dimensional electron diffraction“. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, Nr. 4 (01.08.2019): 550–63. http://dx.doi.org/10.1107/s2052520619007339.

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Diffuse scattering, observed as intensity distribution between the Bragg peaks, is associated with deviations from the average crystal structure, generally referred to as disorder. In many cases crystal defects are seen as unwanted perturbations of the periodic structure and therefore they are often ignored. Yet, when it comes to the structure analysis of nano-volumes, what electron crystallography is designed for, the significance of defects increases. Twinning and polytypic sequences are other perturbations from ideal crystal structure that are also commonly observed in nanocrystals. Here we present an overview of defect types and review some of the most prominent studies published on the analysis of defective nanocrystalline structures by means of three-dimensional electron diffraction.

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Agrawal, Kirti, Syed Mohammad Abid Hasan, Joanna Blawat, Nishir Mehta, Yuming Wang, Rafael Cueto, Miriam Siebenbuerger et al. „Thermal, Physical, and Optical Properties of the Solution and Melt Synthesized Single Crystal CsPbBr3 Halide Perovskite“. Chemosensors 10, Nr. 9 (16.09.2022): 369. http://dx.doi.org/10.3390/chemosensors10090369.

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Inorganic lead-halide perovskite, cesium lead bromide (CsPbBr3), shows outstanding optoelectronic properties. Both solution- and melt-based methods have been proposed for CsPbBr3 crystal growth. The solution-based growth was done at low-temperature, whereas the melt-based growth was done at high-temperature. However, the comparison of optical, physical, and defect states using these two different growth conditions has been scarcely studied. Here, we have compared the thermal and optical properties of solution-grown and melt-grown single crystals of CsPbBr3. Positron Annihilation Lifetime Spectroscopy (PALS) analysis showed that melt-grown crystal has a relatively smaller number of defects than the chemical synthesis method. In addition, crystals grown using the chemical method showed a higher fluorescence lifetime than melt-grown CsPbBr3.

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Ehrlacher, V., C. Ortner und A. V. Shapeev. „Analysis of Boundary Conditions for Crystal Defect Atomistic Simulations“. Archive for Rational Mechanics and Analysis 222, Nr. 3 (22.06.2016): 1217–68. http://dx.doi.org/10.1007/s00205-016-1019-6.

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28

Liao, Jun, und David C. Martin. „Crystal growth and textured microstructures of 1,6-di(N-carbazolyl)-2,4 hexadiyne diacetylene“. Journal of Materials Research 11, Nr. 11 (November 1996): 2921–32. http://dx.doi.org/10.1557/jmr.1996.0370.

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We are developing techniques to isolate and characterize grain boundary defects with controlled geometries in 1,6-di(N-carbazolyl)-2,4 hexadiyne (DCHD) diacetylene polymer bicrystals. To be successful in this endeavor, it is important to determine the influence of processing variables such as evaporation rate, solution concentration, and environment on DCHD diacetylene crystal morphology. We have found that large, high quality DCHD diacetylene single crystals can be grown from solution under a controlled atmosphere. The quality of the DCHD crystals can be evaluated by optical microscopy and quantitative digital image analysis. Defect structures in DCHD diacetylene crystals have been studied by transmission electron microscopy (TEM). Two single-crystal textured structures have been found in porous DCHD crystals precipitated from solution: (1) a microfibrillar structure and (2) a “cross-hatched” structure. The porous DCHD crystals show localized shear deformation zones (twins and kinks), but only in those regions where the density is greater than 95% that of the perfect crystal. Lateral chain invariant (LCI) small-angle grain boundaries have been identified in DCHD by HREM.

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Сидоров, Николай Васильевич, Александра Владимировна Кадетова, Роман Алексеевич Титов, Наталья Александровна Теплякова und Михаил Николаевич Палатников. „SPECIFIC FEATURES OF THE DEFECT STRUCTURE OF LiNbO:B CRYSTALS“. Physical and Chemical Aspects of the Study of Clusters, Nanostructures and Nanomaterials, Nr. 14 (15.12.2022): 235–42. http://dx.doi.org/10.26456/pcascnn/2022.14.235.

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Методом рентгеноструктурного анализа исследованы особенности дефектной структуры номинально чистых кристаллов LiNbO:B, выращенных методом Чохральского по технологии прямого твёрдофазного легирования шихты конгруэнтного состава ортоборной кислотой (HBO). В работе обнаружено, что в кристаллах LiNbO:B длины связей Me-O (Me-Li, Nb) в кислородно-октаэдрических кластерах MeO, ответственных за сегнетоэлектрические и нелинейно оптические свойства кристалла, существенно отличаются от таковых для номинально чистого конгруэнтного кристалла ниобата лития LiNbO. Отличия в длинах связей обусловлены изменением свойств расплава, содержащего бор, технологическими параметрами роста кристаллов LiNbO:B и локализацией следовых количеств бора в тетраэдрических пустотах структуры кристалла ниобата лития. Результаты исследования кристаллов LiNbO:B сравниваются с таковыми для номинально чистых кристаллов LiNbO и LiNbO (5,5 мас.% КО). Specific features of the defect structure of nominally pure LiNbO:B crystals were studied by the X-ray diffraction analysis. Nominally pure LiNbO:B crystals were grown by Czochralski using the technology of the direct solid-phase doping of the congruent charge by orthoboric acid (HBO). The bonds lengths of Me-O in MeO clusters (Me-Li, Nb) determine the ferroelectric and nonlinear optical properties of the lithium niobate crystal. The values of these bonds in LiNbO:B crystals differ significantly from the bonds lengths of the nominally pure congruent crystal LiNbO. The differences in the bonds lengths are caused by a change in the properties of the boron-containing melt, technological parameters of the growth of LiNbO:B crystals, and the localization of a trace amounts of boron in tetrahedral voids of the lithium niobate crystal structure. The results of the study of LiNbO:B crystals were compared with those for nominally pure LiNbO crystals and nearstoichiometric LiNbO (5,5 wt% KO) ones.

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Bozhilov, Krassimir N., Thuy Thanh Le, Zhengxing Qin, Tanguy Terlier, Ana Palčić, Jeffrey D. Rimer und Valentin Valtchev. „Time-resolved dissolution elucidates the mechanism of zeolite MFI crystallization“. Science Advances 7, Nr. 25 (Juni 2021): eabg0454. http://dx.doi.org/10.1126/sciadv.abg0454.

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Zeolite crystal growth mechanisms are not fully elucidated owing to their complexity wherein the formation of a particular zeolite can occur by more than one crystallization pathway. Here, we have conducted time-resolved dissolution experiments of MFI-type zeolite crystals in ammonium fluoride medium where detailed structural analysis allowed us to extrapolate and elucidate the possible mechanism of nucleation and crystal growth. A combination of electron and scanning probe microscopy shows that dissolution initiates preferentially at lattice defects and progressively removes defect zones to reveal a mosaic structure of crystalline domains within each zeolite crystal. This mosaic architecture evolves during the growth process, reflecting the changing conditions of zeolite formation that can be retroactively assessed during zeolite crystal dissolution. Moreover, a more general implication of this study is the establishment that dissolution can be used successfully as an ex situ technique to uncover details about crystal growth features inaccessible by other methods.

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Ozaki, Ryotaro, Hiroshi Moritake, Katsumi Yoshino und Masanori Ozaki. „Analysis of defect mode switching response in one-dimensional photonic crystal with a nematic liquid crystal defect layer“. Journal of Applied Physics 101, Nr. 3 (Februar 2007): 033503. http://dx.doi.org/10.1063/1.2432877.

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Neels, Antonia, Philippe Niedermann und Alex Dommann. „Life Time Predictions through X-Ray Defect Analysis of MEMS Devices“. Materials Science Forum 584-586 (Juni 2008): 518–22. http://dx.doi.org/10.4028/www.scientific.net/msf.584-586.518.

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In single crystal silicon (SCSi) MEMS devices, crystalline imperfection is recognized to favor failure. A DRIE etched SCSi structure was built to study the crystal strain profile in dependence of the SCSi deformation by applying a mechanical force. High resolution X-ray diffraction methods such as the rocking curve method and reciprocal space mapping were used to determine the strain as well as the defect concentration in the crystal. The investigations also include the numerical simulation of deformations.

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LIU JIAN-JUN, ZHANG WAN-LIN und ZHANG GUANG-YIN. „ANALYSIS OF DEFECT STRUCTURE IN Mg-DOPED LiNbO3 CRYSTAL“. Acta Physica Sinica 45, Nr. 11 (1996): 1852. http://dx.doi.org/10.7498/aps.45.1852.

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Komeno, Akira, Yoshio Aoyama, Kenji Toda, Mineo Sato und Kazuyoshi Uematsu. „Structure Analysis of A-Site Defect Perovskite-Type Crystal“. Key Engineering Materials 269 (August 2004): 11–14. http://dx.doi.org/10.4028/www.scientific.net/kem.269.11.

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Wincure, Benjamin M., und Alejandro D. Rey. „Nanoscale Analysis of Defect Shedding from Liquid Crystal Interfaces“. Nano Letters 7, Nr. 6 (Juni 2007): 1474–79. http://dx.doi.org/10.1021/nl0701408.

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Chen, Ying, Pei Luo, Huiying Cao, Zhiyong Zhao und Qiguang Zhu. „Study on sensing property of one-dimensional ring mirror-defect photonic crystal“. International Journal of Modern Physics B 32, Nr. 05 (Februar 2018): 1850049. http://dx.doi.org/10.1142/s0217979218500492.

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Based on the photon localization and the photonic bandgap characteristics of photonic crystals (PCs), one-dimensional (1D) ring mirror-defect photonic crystal structure is proposed. Due to the introduction of mirror structure, a defect cavity is formed in the center of the photonic crystal, and then the resonant transmission peak can be obtained in the bandgap of transmission spectrum. The transfer matrix method is used to establish the relationship model between the resonant transmission peak and the structure parameters of the photonic crystals. Using the rectangular air gate photonic crystal structure, the dynamic monitoring of the detected gas sample parameters can be achieved from the shift of the resonant transmission peak. The simulation results show that the Q-value can attain to 1739.48 and the sensitivity can attain to 1642 nm ⋅ RIU[Formula: see text], which demonstrates the effectiveness of the sensing structure. The structure can provide certain theoretical reference for air pollution monitoring and gas component analysis.

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Li, Hong Jing, und Li An Chen. „Design and Analysis of Self-Collimation-Based Photonic Crystal Beam Splitter“. Advanced Materials Research 887-888 (Februar 2014): 417–21. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.417.

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We present a self-collimation-based beam splitter in a two-dimensional photonic crystal (2D-PC) by introducing defects near the termination. From the equi-frequency contour (EFC) calculations and the finite-difference time-domain (FDTD) simulations, we show that the defects can give rise to the splitting of self-collimated beams in 2D-PCs and the directivity of the deflected beam can be improved by the defect along the PC surface. In order to get different kinds of beam splitters, including the Y-shaped, one-to-three, one-to-four structures, and so on, we only need to modify the structure of the output surface (along X-M direction). The proposed splitter may have practical applications in integrated photonic circuits.

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Titov, Roman A., Alexandra V. Kadetova, Olga V. Tokko, Nikolay V. Sidorov und Mikhail N. Palatnikov. „THE BORON CATION CONCENTRATION INFLUENCE IN LITHIUM NIOBATE CRYSTALS ON THE TYPE AND CONCENTRATION OF POINT STRUCTURAL DEFECTS IN THE CATIONIC SUBLATTICE“. Transactions of the Kоla Science Centre of RAS. Series: Engineering Sciences 14, Nr. 4/2023 (19.04.2023): 106–12. http://dx.doi.org/10.37614/2949-1215.2023.14.4.018.

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Doping a charge of congruent composition (R = [Li]/[Nb] = 0,946) by boric acid leads to an increase in stoichiometry (R = 0,96) of the LiNbO3:B (144·10-5 wt % B in the cone) crystal. The LiNbO3:B crystal was studied by the X-ray diffraction analysis. It was found that in the LiNbO3:B crystal there are no NbLi defects, but there are NbV defects. It has been shown that the localization of the boron cation in the structure of the LiNbO3:B crystal near the NbV defect will be most preferable in the faces of vacant tetrahedral voids common with lithium or vacant oxygen octahedra O6.

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Chen, Huajie, Faizan Q. Nazar und Christoph Ortner. „Geometry equilibration of crystalline defects in quantum and atomistic descriptions“. Mathematical Models and Methods in Applied Sciences 29, Nr. 03 (März 2019): 419–92. http://dx.doi.org/10.1142/s0218202519500131.

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We develop a rigorous framework for modeling the geometry equilibration of crystalline defects. We formulate the equilibration of crystal defects as a variational problem on a discrete energy space and establish qualitatively sharp far-field decay estimates for the equilibrium configuration. This work extends [V. Ehrlacher, C. Ortner and A. Shapeev, Analysis of boundary conditions for crystal defect atomistic simulations, Arch. Ration. Mech. Anal. 222 (2016) 1217–1268] by admitting infinite-range interaction which in particular includes some quantum chemistry based interatomic interactions.

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Yao, Zong Jian, Gui Lan Yu und Yue Sheng Wang. „Finite Element Method for Analysis of Flexural Vibration Propagating in Ternary Phononic Crystal Thin Plates“. Applied Mechanics and Materials 256-259 (Dezember 2012): 596–99. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.596.

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Propagation of flexural vibration in a ternary phononic crystal thin plate with a point defect are explored using finite element method. The thin concrete plate is composed of steel cylinders hemmed around by rubber with a square lattice. Absolute band gaps, point defect bands and transmission response curves with low frequency are investigated. Comparing the results of finite element method with that of improved plane wave expansion method, precise identifications are obtained to identify the point defect states. The results show that the finite element method is suitable for the exploring of flexural vibration propagating in ternary phononic crystal thin plates.

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Kumar, Arun M., und John P. Hirth. „Analysis of extended dislocation faults“. Journal of Materials Research 7, Nr. 7 (Juli 1992): 1718–21. http://dx.doi.org/10.1557/jmr.1992.1718.

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The relative stability of standard extended dislocation dipoles and some new stable defects with lozenge-shaped cross sections have been numerically estimated. An earlier study of these defects in an isotropic fee structure has been extended to the anisotropic case to assess the effect of anisotropy on the calculations. The study is further extended to the case of the L12 crystal structure of the ordered alloy Ni3Al, where the Burgers vectors are large. Results indicate that the introduction of anisotropy has a small effect in determining the relative stability of extended dislocation faults. The results also show that the large values of the Burgers vectors stabilize the arrays in Ni3Al and that the most stable defect favored is the screw lozenge array LD.

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Vasilev, Evgeny. „Defects of diamond crystal structure as an indicator of crystallogenesis“. Записки Горного института 250 (29.09.2021): 481–91. http://dx.doi.org/10.31897/pmi.2021.4.1.

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Based on the study of a representative collections of diamonds from diamondiferous formations of the Urals and deposits of the Arkhangelsk and Yakutian diamond provinces, we established patterns of zonal and sectoral distribution of crystal structure defects in crystals of different morphological types, identified the specifics of crystals formed at different stages of crystallogenesis and performed a comprehensive analysis of constitutional and population diversity of diamonds in different formations. We identified three stages in the crystallogenesis cycle, which correspond to normal and tangential mechanisms of growth and the stage of changing crystal habit shape. At the stage of changing crystal habit shape, insufficient carbon supersaturation obstructs normal growth mechanism, and the facets develop from existing surfaces. Due to the absent stage of growth layer nucleation, formation of new {111} surfaces occurs much faster compared to tangential growth mechanism. This effect allows to explain the absence of cuboids with highly transformed nitrogen defects at the A-B1 stage: they have all been refaceted by a regenerative mechanism. Based on the revealed patterns, a model of diamond crystallogenesis was developed, which takes into account the regularities of growth evolution, thermal history and morphological diversity of the crystals. The model implies the possibility of a multiply repetitive crystallization cycle and the existence of an intermediate chamber; it allows to explain the sequence of changes in morphology and defect-impurity composition of crystals, as well as a combination of constitutional and population diversity of diamonds from different geological formations.

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Stinson, Victoria Paige, Serang Park, Micheal McLamb, Glenn Boreman und Tino Hofmann. „Photonic Crystals with a Defect Fabricated by Two-Photon Polymerization for the Infrared Spectral Range“. Optics 2, Nr. 4 (06.12.2021): 284–91. http://dx.doi.org/10.3390/opt2040027.

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One-dimensional photonic crystals composed of alternating layers with high- and low-density were fabricated using two-photon polymerization from a single photosensitive polymer for the infrared spectral range. By introducing single high-density layers to break the periodicity of the photonic crystals, a narrow-band defect mode is induced. The defect mode is located in the center of the photonic bandgap of the one-dimensional photonic crystal. The fabricated photonic crystals were investigated using infrared reflection measurements. Stratified-layer optical models were employed in the design and characterization of the spectral response of the photonic crystals. A very good agreement was found between the model-calculated and measured reflection spectra. The geometric parameters of the photonic crystals obtained as a result of the optical model analysis were found to be in good agreement with the nominal dimensions of the photonic crystal constituents. This is supported by complimentary scanning electron microscope imaging, which verified the model-calculated, nominal layer thicknesses. Conventionally, the accurate fabrication of such structures would require layer-independent print parameters, which are difficult to obtain with high precision. In this study an alternative approach is employed, using density-dependent scaling factors, introduced here for the first time. Using these scaling factors a fast and true-to-design method for the fabrication of layers with significantly different surface-to-volume ratios. The reported observations furthermore demonstrate that the location and amplitude of defect modes is extremely sensitive to any layer thickness non-uniformities in the photonic crystal structure. Considering these capabilities, one-dimensional photonic crystals engineered with defect modes can be employed as narrow band filters, for instance, while also providing a method to quantify important fabrication parameters.

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Gao, Jin Xia, und Ji Jiang Wu. „Analysis of Defect Modes in One-Dimensional Photonic Crystal with a Dielectric-Superconducting Pair Defect“. Advanced Materials Research 1035 (Oktober 2014): 437–41. http://dx.doi.org/10.4028/www.scientific.net/amr.1035.437.

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One-dimensional dielectric photonic crystals (PCs) with complex substitutional defect layers, consisting of superconducting (SC) and dielectric sublayers are theoretically studied. The influence of the incidence angle on the photonic gap spectra is theoretically analyzed. The pronounced difference in the transmittivity spectra of the PCs with right-handed (RH) and left-handed (LH) positions of the superconducting defect sublayer with respect to the dielectric defect sublayer is demonstrated. It is observed that, for the case of RH SC defect sublayer, the position of the defect mode and the transmittivity at the defect mode frequency strongly depend on the thickness of the superconducting sublayer as well as on the temperature. But the defect modes of the PCs with LH SC defect sublayer are nearly invariant upon the change of the thickness of the superconducting sublayer and the temperature.

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Palatnikov, M. N., A. V. Kadetova, L. A. Aleshina und O. V. Sidorova. „Analysis of doping influence on structural defects in LiNbO3.“ Transaction Kola Science Centre 11, Nr. 3-2020 (25.11.2020): 87–92. http://dx.doi.org/10.37614/2307-5252.2020.3.4.019.

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Changes in a structural state of homogeneous doped lithium niobate crystals with magnesium in the region of 5 mol. % were studied by X-ray diffraction methods. It was found that the changes in the structure of LiNbO3: Mg occured not only in the region of the impurity defect, but also in the region of the main motive of the structure. Bond lengths in the octahedra of the main motive and the Nb–Li distance along the polar axis of the crystal changed. The magnesium introduced into the vacant lithium octahedron distorted the shape of the octahedron more strongly than niobium.

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OHASHI, Tetsuya, Michihiro SATO, Akihito UMANO, Takuya MARUIZUMI und Isao KITAGAWA. „Crystal plasticity analysis of lattice defect generation in ULSI cells“. Proceedings of the JSME annual meeting 2002.2 (2002): 81–82. http://dx.doi.org/10.1299/jsmemecjo.2002.2.0_81.

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Wang, Siyuan, Qian Chen, Yongkai Yuan, Tinghong Gao, Yongchao Liang, Zean Tian und Anqi Yang. „Influence of cooling rate on microstructure and defect evolution in GaAs during solidification“. Modelling and Simulation in Materials Science and Engineering 31, Nr. 8 (06.11.2023): 085018. http://dx.doi.org/10.1088/1361-651x/ad041b.

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Abstract The fabrication of high-quality GaAs crystals is essential to approach optimal performance in optoelectronic and microelectronic devices. In this study, a molecular dynamics simulation study was conducted for the solidification of liquid GaAs at three cooling rates (1010 K s−1, 1011 K s−1, and 1012 K s−1) at 300 K. The structural evolution in terms of crystal structure and defect formation in GaAs was thoroughly investigated using pair distribution function, average atomic energy, the largest standard cluster analysis, and visualization techniques. The results showed that the cooling rate of 1010 K s−1 led to the development of the best crystal quality with ease of eutectic twin grain boundary coherent twin boundary formation. Increasing the cooling rates to 1011 K s−1 and 1012 K s−1 resulted in the amorphous structure. Both high and low cooling rates profoundly affected the formation of As8 structure, but a maximum amount of 2.2% of As8 crystal structure was formed at a cooling rate of 1011 K s−1. The reduction in cooling rate to 1010 K s−1 induced the formation of numerous Schottky and Frenkel types of partial dislocations in the GaAs system. Results of this study can serve as potential guidelines to the theory of crystal growth and may be implemented in the fabrication of high-quality GaAs crystals for optimal device performance.

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Steiner, Johannes, Melissa Roder, Binh Duong Nguyen, Stefan Sandfeld, Andreas Danilewsky und Peter J. Wellmann. „Analysis of the Basal Plane Dislocation Density and Thermomechanical Stress during 100 mm PVT Growth of 4H-SiC“. Materials 12, Nr. 13 (09.07.2019): 2207. http://dx.doi.org/10.3390/ma12132207.

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Basal plane dislocations (BPDs) in 4H silicon carbide (SiC) crystals grown using the physical vapor transport (PVT) method are diminishing the performance of SiC-based power electronic devices such as pn-junction diodes or MOSFETs. Therefore, understanding the generation and movement of BPDs is crucial to grow SiC suitable for device manufacturing. In this paper, the impact of the cooldown step in PVT-growth on the defect distribution is investigated utilizing two similar SiC seeds and identical growth parameters except for a cooldown duration of 40 h and 70 h, respectively. The two resulting crystals were cut into wafers, which were characterized by birefringence imaging and KOH etching. The initial defect distribution of the seed wafer was characterized by synchrotron white beam X-ray topography (SWXRT) mapping. It was found that the BPD density increases with a prolonged cooldown time. Furthermore, small angle grain boundaries based on threading edge dislocation (TED) arrays, which are normally only inherited by the seed, were also generated in the case of the crystal cooled down in 70 h. The role of temperature gradients inside the crystal during growth and post-growth concerning the generation of shear stress is discussed and supported by numerical calculations.

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Moralejo, Benito, Vanesa Hortelano, Oscar Martínez, Juan Jiménez, Miguel Angel González, Ismael Guerrero und Vicente Parra. „Combined EL and LBIC Study of the Electrical Activity of Defects in Solar Cells Based on Innovative Wafers Grown by Casting Methods“. Materials Science Forum 725 (Juli 2012): 137–40. http://dx.doi.org/10.4028/www.scientific.net/msf.725.137.

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In this paper we combine LBIC and EL measurements of commercially multi-crystalline silicon solar cells, in order to obtain detailed information about the electrical activity around defect areas. This integrated analysis is suitable for the study of different crystal defects at both micrometric and full wafer scale. In particular, the electrical activity of some defect areas is studied in detail by means of highly spatially-resolved LBIC maps, showing important differences in their behaviours. A discussion about the origin of these differences is presented.

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Yu, Jianyuan, Yingeng Wang, Yan Huang, Xiuwen Wang, Jing Guo, Jingkai Yang und Hongli Zhao. „Structural and electronic properties of SnO2 doped with non-metal elements“. Beilstein Journal of Nanotechnology 11 (03.09.2020): 1321–28. http://dx.doi.org/10.3762/bjnano.11.116.

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Crystal structure and electronic properties of SnO2 doped with non-metal elements (F, S, C, B, and N) were studied using first-principles calculations. The theoretical results show that doping of non-metal elements cannot change the structure of SnO2 but result in a slight expansion of the lattice volume. The most obvious finding from the analysis is that F-doped SnO2 has the lowest defect binding energy. The doping with B and S introduced additional defect energy levels within the forbidden bandgap, which improved the crystal conductivity. The Fermi level shifts up due to the doping with B, F, and S, while the Fermi level of SnO2 doped with C or N has crossed the impurity level. The Fermi level of F-doped SnO2 is inside the conduction band, and the doped crystal possesses metallicity. The optical properties of SnO2 crystals doped with non-metal elements were analyzed and calculated. The SnO2 crystal doped with F had the highest reflectivity in the infrared region, and the reflectance of the crystals doped with N, C, S, and B decreased sequentially. Based on this theoretical calculations, F-doped SnO2 is found to be the best photoelectric material for preparing low-emissivity coatings.

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