Journal articles: 'Crystal field'

1

Ross, Nancy L., and John R. Sowerby. "High-pressure crystal-field spectra of single-crystal clinoferrosilite." European Journal of Mineralogy 11, no. 5 (September 30, 1999): 791–802. http://dx.doi.org/10.1127/ejm/11/5/0791.

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Rossano, Stéphanie, Laurence Galoisy, and Gabriel Gwamnesia. "Crystal-field spectrum of γ-Ni2SiO4." European Journal of Mineralogy 8, no. 3 (June 17, 1996): 471–76. http://dx.doi.org/10.1127/ejm/8/3/0471.

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Ryu, Sun Young, In Hwan Oh, Sang Jin Cho, Shin Ae Kim, and Hyun Kyu Song. "Enhancing Protein Crystallization under a Magnetic Field." Crystals 10, no. 9 (September 16, 2020): 821. http://dx.doi.org/10.3390/cryst10090821.

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High-quality crystals are essential to ensure high-resolution structural information. Protein crystals are controlled by many factors, such as pH, temperature, and the ion concentration of crystalline solutions. We previously reported the development of a device dedicated to protein crystallization. In the current study, we have further modified and improved our device. Exposure to external magnetic field leads to alignment of the crystal toward a preferred direction depending on the magnetization energy. Each material has different magnetic susceptibilities depending on the individual direction of their unit crystal cells. One of the strategies to acquire a large crystal entails controlling the nucleation rate. Furthermore, exposure of a crystal to a magnetic field may lead to new morphologies by affecting the crystal volume, shape, and quality.

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Choudhury, P. K. "Evanescent Field Enhancement in Liquid Crystal Optical Fibers: A Field Characteristics Based Analysis." Advances in Condensed Matter Physics 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/504868.

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The paper presents the analysis of the electromagnetic wave propagation through liquid crystal optical fibers (LCOFs) of two different types—conventional guides loaded with liquid crystals (addressed as LCOFs) and those with additional twists due to conducting helical windings (addressed as HCLCOFs). More precisely, the three-layer optical waveguide structures are considered along with its outermost region being loaded with radially anisotropic liquid crystal material and the inner regions being made of usual silica, as used in conventional optical fibers. In addition to that, LCOF with twists introduced in the form of conducting helical windings at the interface of the silica core and the liquid crystal clad is also taken into account. Emphasis has been put on the power confinements by the lower-order TE modes sustained in the different sections of the LCOF structure. The results demonstrate useful applications of these guides in integrated optics as the power sustained in the liquid crystal section by the excited TE modes remains very high. In the case of twisted clad liquid crystal guides, descriptions are limited to the nature of dispersion relation only under the TE mode excitation, and corresponding to the cases of helix orientations being parallel and perpendicular to the optical axis.

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Tang, Xia, Botao Liu, Yue Yu, Sheng Liu, and Bing Gao. "Numerical Analysis of Difficulties of Growing Large-Size Bulk β-Ga2O3 Single Crystals with the Czochralski Method." Crystals 11, no. 1 (December 30, 2020): 25. http://dx.doi.org/10.3390/cryst11010025.

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The difficulties in growing large-size bulk β-Ga2O3 single crystals with the Czochralski method were numerically analyzed. The flow and temperature fields for crystals that were four and six inches in diameter were studied. When the crystal diameter is large and the crucible space becomes small, the flow field near the crystal edge becomes poorly controlled, which results in an unreasonable temperature field, which makes the interface velocity very sensitive to the phase boundary shape. The effect of seed rotation with increasing crystal diameter was also studied. With the increase in crystal diameter, the effect of seed rotation causes more uneven temperature distribution. The difficulty of growing large-size bulk β-Ga2O3 single crystals with the Czochralski method is caused by spiral growth. By using dynamic mesh technology to update the crystal growth interface, the calculation results show that the solid–liquid interface of the four-inch crystal is slightly convex and the center is slightly concave. With the increase of crystal growth time, the symmetry of cylindrical crystal will be broken, which will lead to spiral growth. The numerical results of the six-inch crystal show that the whole solid–liquid interface is concave and unstable, which is not conducive to crystal growth.

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He, Xinke, Linnong Li, Xinqi He, and Chao Xie. "Multi-Physical Field Simulation of Cracking during Crystal Growth by Bridgman Method." Materials 16, no. 8 (April 20, 2023): 3260. http://dx.doi.org/10.3390/ma16083260.

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Crystal materials are prone to cracking during growth, which is a key problem leading to slow growth and difficulty in forming large-size crystals. In this study, based on the commercial finite element software COMSOL Multiphysics, the transient finite element simulation of the multi-physical field, including fluid heat transfer—phase transition—solid equilibrium—damage coupling behaviors, is performed. The phase-transition material properties and maximum tensile strain damage variables are customized. Using the re-meshing technique, the crystal growth and damage are captured. The results show the following: The convection channel at the bottom of the Bridgman furnace greatly influences the temperature field inside the furnace, and the temperature gradient field significantly influences the solidification and cracking behaviors during crystal growth. The crystal solidifies faster when it enters the higher-temperature gradient region and is prone to cracking. The temperature field inside the furnace needs to be properly adjusted so that the crystal temperature decreases relatively uniformly and slowly during the growth process to avoid crack formation. In addition, the crystal growth orientation also significantly affects the nucleation and growth direction of cracks. Crystals grown along the a-axis tend to form long cracks starting from the bottom and growing vertically, while crystals grown along the c-axis induce the laminar cracks from the bottom in a horizontal direction. The numerical simulation framework of the damage during crystal growth, which can accurately simulate the process of crystal growth and crack evolution and can be used to optimize the temperature field and crystal growth orientation in the Bridgman furnace cavity, is a reliable method to solve the crystal cracking problem.

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Voronin, Vladimir, Valery Fedorov, Sergey Semenikhin, and Yaroslav Berdnikov. "Neutron spin rotation effect at Laue diffraction in a weakly deformed and nonabsorbing crystal with no center of symmetry." EPJ Web of Conferences 219 (2019): 06003. http://dx.doi.org/10.1051/epjconf/201921906003.

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The effect of the neutron spin rotation at Laue diffraction in a weakly deformed noncentrosymmetric and transparent for the neutrons crystal has been theoretically described and experimentally investigated. This effect arises in the deformed crystal because of the curvature of the neutron trajectory in the crystal. A certain type of deformation leads to the escape outside the crystal of one of the two neutron waves excited at Laue diffraction. This two waves propagate in the crystal without a center of symmetry in electric fields with the opposite sign. In this case the spin of the remaining neutron wave will be rotating relative to the original direction due to the interaction of the magnetic moment of the moving neutron with the crystal's intracrystalline electric field. In a perfect undeformed crystal such spin rotation effect is absent. There is only a depolarization of the beam since both waves in opposite electric fields are present with the same amplitudes. A technique for controlled deformation of a perfect single crystal by creating a temperature gradient has been developed. Thus a new possibility to measure the electric fields which act on the neutron in noncentrosymmetric crystals has been realized. There also appeared a way to control these fields in experiments on the study of the neutron fundamental properties.

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Bulutoglu, Pelin Su, Conor Parks, Nandkishor K. Nere, Shailendra Bordawekar, and Doraiswami Ramkrishna. "Exploring New Crystal Structures of Glycine via Electric Field-Induced Structural Transformations with Molecular Dynamics Simulations." Processes 7, no. 5 (May 8, 2019): 268. http://dx.doi.org/10.3390/pr7050268.

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Being able to control polymorphism of a crystal is of great importance to many industries, including the pharmaceutical industry, since the crystal’s structure determines significant physical properties of a material. While there are many conventional methods used to control the final crystal structure that comes out of a crystallization unit, these methods fail to go beyond a few known structures that are kinetically accessible. Recent studies have shown that externally applied fields have the potential to effectively control polymorphism and to extend the set of observable polymorphs that are not accessible through conventional methods. This computational study focuses on the application of high-intensity dc electric fields (e-fields) to induce solid-state transformation of glycine crystals to obtain new polymorphs that have not been observed via experiments. Through molecular dynamics simulations of solid-state α -, β -, and γ -glycine crystals, it has been shown that the new polymorphs sustain their structures within 125 ns after the electric field has been turned off. It was also demonstrated that strength and direction of the electric field and the initial structure of the crystal are parameters that affect the resulting polymorph. Our results showed that application of high-intensity dc electric fields on solid-state crystals can be an effective crystal structure control method for the exploration of new crystal structures of known materials and to extend the range of physical properties a material can have.

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9

Bai, Minyu, Shuai Wen, Jijie Zhao, Yuxuan Du, Fei Xie, and Huan Liu. "Effect of Carrier Gas Flow Field on Chemical Vapor Deposition of 2D MoS2 Crystal." Coatings 11, no. 5 (May 6, 2021): 547. http://dx.doi.org/10.3390/coatings11050547.

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The carrier gas flow field plays a vital role in the chemical vapor deposition (CVD) process of two dimensional (2D) MoS2 crystal, which was studied by simulations and experiments. Different carrier gas flow fields were studied by utilizing three types of precursor carrier which affected the local gas flow field significantly. The experiment results showed that the appropriate precursor vapor concentration could be achieved by local carrier gas flow field conditioning, resulting in single 2D MoS2 crystals of a large size and a high coating rate of 2D MoS2 crystal on the target substrate surface. The carrier gas flow also contributed to the growth of the 2D MoS2 crystal when it flew towards the target surface. The size of deposited single 2D MoS2 crystal reached tens of micrometers and a few layers of 2D MoS2 crystal were characterized and confirmed.

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10

Zhong, Z., M. Hasnah, A. Broadbent, E. Dooryhee, and M. Lucas. "Phase-space matching between bent Laue and flat Bragg crystals." Journal of Synchrotron Radiation 26, no. 6 (October 23, 2019): 1917–23. http://dx.doi.org/10.1107/s1600577519010774.

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Through phase-space analysis of Dumond diagrams for a flat Bragg crystal, a single bent Laue crystal and a monochromator consisting of double-bent Laue crystals, this work shows that it is possible to match the flat Bragg crystal to both the single-crystal and double-crystal Laue monochromators. The matched system has the advantage that the phase space of the bent crystal's output beam is much larger than that of the flat crystal, making the combined system stable. Here it is suggested that such a matched system can be used at synchrotron facilities to realize X-ray dark-field imaging, analyzer-based imaging and diffraction-enhanced imaging at beamlines using double-Laue monochromators.

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11

Zhang, Dianxi, Xiufan Yang, Huaizhi Wang, and Qingjiang Song. "Phase Field Simulation Research on the Microstructural Evolution of Monocrystalline and Polycrystalline Silicon." Crystals 12, no. 9 (September 7, 2022): 1271. http://dx.doi.org/10.3390/cryst12091271.

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This work simulates the morphological evolution process of the solidification interface of silicon crystal. Based on the phase field model of single dendrite growth of pure material in a single-phase system, the control equation of the phase field is re-optimized, and an interface free energy anisotropy equation that can simulate the competitive growth of multiple crystal grains is established. The competitive growth of polysilicon is then simulated and analyzed. The results show that when the degree of undercooling exceeds a certain value, the non-facet crystals are transformed into facet crystals. The main branches in each direction are relatively thick when the anisotropy is small. With increasing anisotropy, the main branches in each direction show gradual thinning, and edges and corners appear on the interface. The dendrites are no longer smooth, and they transform from non-facet crystals to facet crystals. The main branches of different grains inhibit each other when multiple crystal grains compete for growth. The growth of the main branches is curved, which is different from existing branches. The experimental results can more realistically simulate the evolution process of single-crystal silicon and polycrystalline silicon crystal micromorphology.

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12

Ma, Nancy, John Walker, David Bliss, and George Bryant. "Forced Convection During Liquid Encapsulated Crystal Growth With an Axial Magnetic Field." Journal of Fluids Engineering 120, no. 4 (December 1, 1998): 844–50. http://dx.doi.org/10.1115/1.2820749.

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This paper treats the forced convection, which is produced by the rotation of the crystal about its vertical centerline during the liquid-encapsulated Czochralski or Kyropoulos growth of compound semiconductor crystals, with a uniform vertical magnetic field. The model assumes that the magnetic field strength is sufficiently large that convective heat transfer and all inertial effects except the centripetal acceleration are negligible. With the liquid encapsulant in the radial gap between the outside surface of the crystal and the vertical wall of the crucible, the forced convection is fundamentally different from that with a free surface between the crystal and crucible for the Czochralski growth of silicon crystals. Again unlike the case for silicon growth, the forced convection for the actual nonzero electrical conductivity of an indium-phosphide crystal is virtually identical to that for an electrically insulating crystal. The electromagnetic damping of the forced convection is stronger than that of the buoyant convection. In order to maintain a given balance between the forced and buoyant convections, the angular velocity of the crystal must be increased as the magnetic field strength is increased.

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13

Brik, M. G., and A. A. Chaykin. "Comparative crystal field study of Ni2+ energy levels and crystal field effects in CsCdBr3 and CsMgBr3 crystals." Journal of Luminescence 145 (January 2014): 563–68. http://dx.doi.org/10.1016/j.jlumin.2013.08.037.

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14

Löwen, Hartmut. "A phase-field-crystal model for liquid crystals." Journal of Physics: Condensed Matter 22, no. 36 (August 20, 2010): 364105. http://dx.doi.org/10.1088/0953-8984/22/36/364105.

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15

Buček, Slavko, Samo Kralj, and T. J. Sluckin. "Hysteresis in Two-Dimensional Liquid Crystal Models." Advances in Condensed Matter Physics 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/834867.

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We make a numerical study of hysteresis loop shapes within a generalized two-dimensional Random Anisotropy Nematic (RAN) model at zero temperature. The hysteresis loops appear on cycling a static external ordering field. Ordering in these systems is history dependent and involves interplay between the internal coupling constantJ, the anisotropy random fieldD, and the ordering external fieldH. Here the external field is represented by a traceless tensor, analogous to extension-type fields in continuum mechanics. The calculations use both a mean field approach and full lattice simulations. Our analysis suggests the existence of two qualitatively different solutions, which we denote assymmetricandsymmetry breaking. For the set of parameters explored, only the symmetric solutions are stable. Both approaches yield qualitatively similar hysteresis curves, which are manifested either by single or double loops. But the quantitative differences indicate that mean field estimates are only of limited predictive value.

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16

Siu, G. G. "The magnetically correlated crystal field and correlation in crystal-field theory." Journal of Physics C: Solid State Physics 20, no. 14 (May 20, 1987): 2097–108. http://dx.doi.org/10.1088/0022-3719/20/14/011.

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17

English, Niall J. "Molecular Simulation of External Electric Fields on the Crystal State: A Perspective." Crystals 11, no. 11 (November 18, 2021): 1405. http://dx.doi.org/10.3390/cryst11111405.

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Unpacking the mechanistic insights into how externally applied electric fields affect the physicochemical properties of crystals represents a challenge of great importance for a plethora of natural phenomena, in addition to a broad array of industrial operations and technologies. As such, the key goals in such field effect studies centre around how thermodynamic and kinetic relaxation processes in crystals are affected, including charge carrier conduction and energy transfer processes, and this is a very recent area of fundamental scrutiny. Indeed, in recent years, there has been a steadily mounting number of reports of field-manipulated crystal-state phenomena. Taking as the background a range of natural phenomena, phenomenological theory, state-of-the-art experiments and technological observations, the present review examines the role of nonequilibrium molecular simulation in its scrutiny of intra-crystal phenomena from an atomistic viewpoint, in addition to providing a framework for a predictive molecular design philosophy by which to refine field crystal understanding.

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18

Sathishkumar, G., M. Lenin, T. Gubendiran, B. Sathiyamoorthy, S. Nithiyanantham, and P. Ramasamy. "Structural, electrical and optical studies on organic NLO single crystal of N‐benzyl‐2‐methyl‐4‐nitroaniline (BNA)." Vietnam Journal of Chemistry 61, no. 6 (December 2023): 778–87. http://dx.doi.org/10.1002/vjch.202300129.

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AbstractThe 2‐methyl‐4‐nitroaniline (NA) was converted into the raw material N‐benzyl‐2‐methyl‐4‐nitroaniline (BNA), and the solubility of BNA in various organic solvents was calculated gravimetrically. BNA's solubility and crystal structure make it an excellent solvent for the low‐temperature solution growth method used to create single crystals of BNA with orthorhombic structure studied through single crystal analysis. Methanol was used to harvest the 3×10 mm3 BNA single crystals, which are big, translucent yellow crystals. BNA, the subject compound, the exothermic and endothermic nature was characterised by TG analyses, differential scanning calorimeter (DSC), functional studies by infrared (IR) spectra, NMR spectral and optical transmission studies. An Nd:YAG laser (1064 nm) was used to observe the second harmonic generation (SHG) of grown crystal leads about 3 times more than KDP crystal. Possible polarization for various temperatures, the crystal's dielectric properties was measured as a function of frequency. Larger surface morphology with high optical to wave conversion efficiency and the results were reviewed. Responding to electric field to leads to liquid crystal display and THz purposes.

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Ren, Fude, Xiaolei Wang, Qing Zhang, Xiaojun Wang, Lingling Chang, and Zhiteng Zhang. "Experimental and Theoretical Investigation of External Electric-Field-Induced Crystallization of TKX-50 from Solution by Finite-Temperature String with Order Parameters as Collective Variables for Ionic Crystals." Molecules 29, no. 5 (March 5, 2024): 1159. http://dx.doi.org/10.3390/molecules29051159.

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External electric fields are an effective tool to induce phase transformations. The crystallization of ionic crystals from solution is a common phase transformation. However, understanding of mechanisms is poor at the molecular level. In this work, we carried out an experimental and theoretical investigation of the external electric-field-induced crystallization of TKX-50 from saturated formic acid solution by finite-temperature string (FTS) with order parameters (OPs) as collective variables for ionic crystals. The minimum-free-energy path was sketched by the string method in collective variables. The results show that the K-means clustering algorithm based on Euclidean distance and density weights can be used for enhanced sampling of the OPs in external electric-field-induced crystallization of ionic crystal from solution, which improves the conventional FTS. The crystallization from solution is a process of surface-mediated nucleation. The external electric field can accelerate the evolution of the string and decrease the difference in the potential of mean forces between the crystal and the transition state. Due to the significant change in OPs induced by the external electric field in nucleation, the crystalline quality was enhanced, which explains the experimental results that the external electric field enhanced the density, detonation velocity, and detonation pressure of TKX-50. This work provides an effective way to explore the crystallization of ionic crystals from solution at the molecular level, and it is useful for improving the properties of ionic crystal explosives by using external electric fields.

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20

Yao, Xiaogang, Zhen Kong, Shengfu Liu, Yong Wang, Yongliang Shao, Yongzhong Wu, and Xiaopeng Hao. "Comparative Studies of c- and m-Plane AlN Seeds Grown by Physical Vapor Transport." Materials 15, no. 24 (December 9, 2022): 8791. http://dx.doi.org/10.3390/ma15248791.

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The ultra-wide bandgap semiconductor AlN has attracted a great deal of attention owing to its wide application potential in the field of electronics and optoelectronic devices. In this report, based on the mechanism of the physical vapor transport (PVT) growth of AlN crystal, the c- and m-plane AlN seed crystals were prepared simultaneously through special temperature field design. It is proved that AlN crystals with different orientations can be obtained at the same temperature field. The structure parameter of AlN crystal was obtained through the characteristic evaluations. In detail, XPS was used to analyze the chemical states and bonding states of the surface of seed crystals. The content of oxygen varied along with distinct orientations. Raman spectrum documented a small level of compressive stress on these crystal seeds. Tested results confirmed that the prepared AlN crystal seeds had high quality.

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21

Zhang, Shengtao, Guofeng Fan, Tie Li, and Lili Zhao. "Optimization of thermal field of 150 mm SiC crystal growth by PVT method." RSC Advances 12, no. 31 (2022): 19936–45. http://dx.doi.org/10.1039/d2ra02875a.

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The effects of thermal insulation adjustment, application of seed crystals with different diameters, and shelter structure on crystal growth process were studied, and 6-inch SiC crystal with single polytype, high quality was successfully prepared.

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22

Park, J. G., D. T. Adroja, K. A. McEwen, Y. J. Bi, and J. Kulda. "Crystal field excitation of single crystal CeNiSn." Physica B: Condensed Matter 259-261 (January 1999): 288–89. http://dx.doi.org/10.1016/s0921-4526(98)00827-8.

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23

Kajkowska, Marta, Miłosz Chychłowski, and Piotr Lesiak. "Influence of photopolymerization on propagation properties of photonic crystal fiber infiltrated with liquid crystal mixture." Photonics Letters of Poland 14, no. 3 (September 30, 2022): 68. http://dx.doi.org/10.4302/plp.v14i3.1166.

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In this paper we analyze the influence of the photopolymerization process on propagation properties of photonic crystal fiber infiltrated with liquid crystal doped with a mixture of reactive monomer and photoinitiator. The obtained results showed changes in photonic band gap of the fiber due to refractive index change of the liquid crystal mixture caused by the polymerization process. Moreover, the research demonstrated the possibility of preserving the desired molecular orientation of liquid crystal initially stabilized by placing the sample in the external electric field. This was achieved by simultaneously irradiating the sample and controlling the orientation of liquid crystal molecules with the electric field. The spectral analysis of the polymerized sample showed no visible difference in propagation spectra when the electric field was turned off after the process was finished. Full Text: PDF ReferencesK. Yin et al., "Advanced liquid crystal devices for augmented reality and virtual reality displays: principles and applications", Light Sci Appl. 11, 161 (2022). CrossRef S. Singh, "Phase transitions in liquid crystals", Phys. Rep. 324, 107 (2000). CrossRef N. Tarjányi, M. Veveričík, D. Káčik, M. Timko, P. Kopčanský, "Birefringence dispersion of 6CHBT liquid crystal determined in VIS-NIR spectral range", Appl. Surf. Sci. 542, 148525 (2021). CrossRef R. Dąbrowski, P. Kula, J. Herman, "High Birefringence Liquid Crystals", Crystals 3, 443 (2013). CrossRef R. H. Self, C. P. Please, T. J. Sluckin, "Deformation of nematic liquid crystals in an electric field", Eur. J. Appl. Math. 13, 1 (2002). CrossRef T. Hegmann, H. Qi, V. M. Marx, "Nanoparticles in Liquid Crystals: Synthesis, Self-Assembly, Defect Formation and Potential Applications", J. Inorg. Organomet. Polym. 17, 483 (2007). CrossRef S. Kaur, S. P. Singh, A. M. Biradar, A. Choudhary, K. Sreenivas, "Enhanced electro-optical properties in gold nanoparticles doped ferroelectric liquid crystals", Appl. Phys. Lett. 91, 023120 (2007). CrossRef I. Dierking, "Polymer Network–Stabilized Liquid Crystals", Adv. Mater. 12, 167 (2000). CrossRef D. C. Hoekstra et al., "Wavelength-Selective Photopolymerization of Hybrid Acrylate-Oxetane Liquid Crystals", Angew. Chem. Int. Ed. 60, 10935 (2021). CrossRef Z. Ge, S. Gauza, M. Jiao, H. Xianyu, S.-T. Wu, "Electro-optics of polymer-stabilized blue phase liquid crystal displays", Appl. Phys. Lett. 94, 101104 (2009). CrossRef M. S. Chychłowski et al., "Locally-induced permanent birefringence by polymer-stabilization of liquid crystal in cells and photonic crystal fibers", Opto-electron. Rev. 26, 242 (2018). CrossRef R. Dąbrowski, J. Dziaduszek, T. Szczuciński, "Mesomorphic Characteristics of Some New Homologous Series with the Isothiocyanato Terminal Group", Mol. Cryst. Liq. Cryst. 124, 241 (1985). CrossRef

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Zou, Zhigang, Jinhua Ye, Kunihiko Oka, and Yoshikazu Nishihara. "Characterization of Superconducting PrBa2Cu3Ox." International Journal of Modern Physics B 12, no. 29n31 (December 20, 1998): 3242–50. http://dx.doi.org/10.1142/s0217979298002398.

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The crystal structures of superconducting and nonsuperconducting PrBa2Cu3O x crystals were investigated using a single crystal X-ray precession camera. A large amount of stacking faults were observed in h0l reflections of as-grown supconducting PrBa2Cu3O x single crystals. These diffusing could be relaxed after oxygen annealing. Meanwhile, intensities of 003n (n = 1, 2, 3…) diffraction reflections of annealed crystal were increased significantly, indicating that the structural ordering of 1/3n unit cell was improved. Magnetic measurement exhibited that the superconducting state of PrBa2Cu3O x , is sensitive to magnetic fields and the magnetic fields dependence of the flux melting temperature showed that the sample has the smaller critical magnetic field than YBa2Cu3O x.

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Chang, Guo Wei, Shu Ying Chen, Qing Chun Li, Li Li Guo, and Xu Dong Yue. "Effect of Pulse Electric Field on the Columnar Crystals Growth of Al-5.6 Wt.%Cu during Unidirectional Solidification." Advanced Materials Research 299-300 (July 2011): 345–49. http://dx.doi.org/10.4028/www.scientific.net/amr.299-300.345.

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The influence of pulse electric field on the columnar crystals growth has been studied by employing pulse electric field vertically to the solid/liquid interface during unidirectional solidification. The results showed that the pulse electric field was favorable to columnar crystals growth with the increase of pulse electric field intensity when the liquid phase was the positive electrode of pulse electric field. The formation of equiaxed crystal was accelerated when the degree of composition supercooling in front edge of solid/liquid interface reached the degree of nucleation supercooling by pulse electric field. When the liquid phase was the negative electrode of pulse electric field, the growth of columnar crystals was hindered, and the formation of equiaxed crystal was accelerated by pulse electric field.

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Jung, Jae Kap, Hae Jin Kim, Kee Tae Han, and Sung Ho Choh. "Electric Field Effect on NQR in Ferroelectric Materials." Zeitschrift für Naturforschung A 51, no. 5-6 (June 1, 1996): 646–50. http://dx.doi.org/10.1515/zna-1996-5-645.

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Abstract The electric field effect on NQR in ferroelectric materials, 93Nb in LiNbO3 and 14N in NaNO2 and SC(NH2)2 , has been investigated at 77 K. In these crystals with single domain, only the line shift due to the external electric field was observed. In the case of NaNO2 powder and a crystal with multi-domains, line broadening was observed in the external electric field. These phenomena can be explained with the fact that the direction of spontaneous polarization in a domain is related to the direction of the applied electric field. The rate of the NQR line-shift due to the electric field is remarkably smaller in mostly ionic crystals, such as LiNbO3 and NaNO2 , than in a molecular crystal such as SC(NH2)2 . This is due to the strong ionic bonding in ionic crystals. Also, the difference of the Stark shift'between NaNO2 and SC(NH2)2 is discussed in terms of the local electric field and polarizability at the resonant nuclear site.

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Chen, Chen, Xiao-Tong He, Dan-Li Hong, Jing-Wen Wang, Yang-Hui Luo, and Bai-Wang Sun. "Tuning the crystal structures of metal-tetraphenylporphines via a magnetic field." New Journal of Chemistry 42, no. 15 (2018): 12570–75. http://dx.doi.org/10.1039/c8nj01882k.

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In this work, two new single crystals of copper-tetraphenylporphine (Cu-TPP) (crystals 2 and 3), which were induced by external magnetic fields with strengths of 0.5 and 0.8 T, respectively, have been prepared and characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis.

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Chitra, R., and T. Giamarchi. "Zero field Wigner crystal." European Physical Journal B 44, no. 4 (April 2005): 455–67. http://dx.doi.org/10.1140/epjb/e2005-00145-0.

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29

Kern, S., R. A. Robinson, H. Nakotte, G. H. Lander, B. Cort, P. Watson, and F. A. Vigil. "Crystal-field transition inPuO2." Physical Review B 59, no. 1 (January 1, 1999): 104–6. http://dx.doi.org/10.1103/physrevb.59.104.

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30

Goremychkin, E. A., and R. Osborn. "Crystal-field excitations inCeCu2Si2." Physical Review B 47, no. 21 (June 1, 1993): 14280–90. http://dx.doi.org/10.1103/physrevb.47.14280.

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Toliński, T., A. Hoser, S. Rols, A. Kowalczyk, and A. Szlaferek. "Crystal field states in." Solid State Communications 149, no. 47-48 (December 2009): 2240–43. http://dx.doi.org/10.1016/j.ssc.2009.09.002.

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Faucher, M., D. Garcia, and O. K. Moune. "Applied correlated crystal field." Journal of Alloys and Compounds 193, no. 1-2 (March 1993): 210–12. http://dx.doi.org/10.1016/0925-8388(93)90351-m.

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33

OKUYAMA, F. "HIGH-FIELD CRYSTAL GROWTH." Le Journal de Physique Colloques 47, no. C7 (November 1986): C7–75—C7–80. http://dx.doi.org/10.1051/jphyscol:1986714.

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34

Muzichka, Y. U., E. A. Goremychkin, I. V. Sashin, M. Diviš, V. Nekvasil, M. Nevřiva, and G. Fillion. "Crystal field in Nd2CuO4." Solid State Communications 82, no. 6 (May 1992): 461–64. http://dx.doi.org/10.1016/0038-1098(92)90750-4.

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Gubbens, P. C. M., A. M. van der Kraan, and K. H. J. Buschow. "Crystal field in Tm2Ni17." Journal of Magnetism and Magnetic Materials 54-57 (February 1986): 483–84. http://dx.doi.org/10.1016/0304-8853(86)90674-8.

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36

Shigeoka, T., N. Iwata, and H. Fujii. "Crystal field in NdMn2Ge2." Journal of Magnetism and Magnetic Materials 76-77 (December 1988): 189–90. http://dx.doi.org/10.1016/0304-8853(88)90362-9.

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Mulak, Maciej, and Jacek Mulak. "Crystal Field Rotational Invariants: A New Light on the Crystal Field Effects." physica status solidi (b) 257, no. 8 (April 29, 2020): 2000064. http://dx.doi.org/10.1002/pssb.202000064.

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38

Ciciulla, Fabrizio, Annamaria Zaltron, Riccardo Zamboni, Cinzia Sada, Francesco Simoni, Victor Yu Reshetnyak, and Liana Lucchetti. "Optofluidic Platform Based on Liquid Crystals in X-Cut Lithium Niobate: Thresholdless All-Optical Response." Crystals 11, no. 8 (August 2, 2021): 908. http://dx.doi.org/10.3390/cryst11080908.

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In this study, we present a new configuration of the recently reported optofluidic platform exploiting liquid crystals reorientation in lithium niobate channels. In order to avoid the threshold behaviour observed in the optical control of the device, we propose microchannels realized in a x-cut crystal closed by a z-cut crystal on the top. In this way, the light-induced photovoltaic field is not uniform inside the liquid crystal layer and therefore the conditions for a thresholdless reorientation are realized. We performed simulations of the photovoltaic effect based on the well assessed model for Lithium Niobate, showing that not uniform orientation and value of the field should be expected inside the microchannel. In agreement with the re-orientational properties of nematic liquid crystals, experimental data confirm the expected thresholdless behaviour. The observed liquid crystal response exhibits two different regimes and the response time shows an unusual dependence on light intensity, both features indicating the presence of additional photo-induced fields appearing above a light intensity of 107 W/m2.

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39

Prijamboedi, B., E. Maryanti, and T. Haryati. "Preparation of vertically aligned ZnO crystal rods in aqueous solution at external electric field." Materials Science-Poland 32, no. 2 (June 1, 2014): 157–63. http://dx.doi.org/10.2478/s13536-013-0191-8.

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AbstractIn this study, an external electric field was used to facilitate the growth of vertically aligned ZnO crystal rods on the surface of indium tin oxide (ITO) glass substrates in an aqueous solution. We used Zn(NO3) and C6H12N4 as precursor and reagent. We found that the external electric field generated by DC potential of 5 kV between two electrodes that were placed outside the bottle could facilitate the growth of homogeneous, high density and vertically aligned ZnO crystal rods. Position of the substrate during the growth of crystal was found to be important to obtain well aligned crystal. The crystals that were grown near the negative electrode had the best properties. Photoluminescence measurement at room temperature revealed sharp peaks at around 360 and 380 nm and a broad peak around 420 nm that indicated good properties of ZnO crystals grown with external electric field.

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40

Li, Chen, Changqin Ding, Minghe Li, Jiayue Rong, Hilary Florian, and Garth Simpson. "Depth-of-field extension in optical imaging for rapid crystal screening." Acta Crystallographica Section D Structural Biology 77, no. 4 (March 30, 2021): 463–70. http://dx.doi.org/10.1107/s2059798321000097.

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The depth of field (DoF) was extended 2.8-fold to achieve rapid crystal screening by retrofitting a custom-designed micro-retarder array (µRA) in the optical beam path of a nonlinear optical microscope. The merits of the proposed strategy for DoF enhancement were assessed in applications of second-harmonic generation imaging of protein crystals. It was found that DoF extension increased the number of crystals detected while simultaneously reducing the number of `z-slices' required for screening. Experimental measurements of the wavelength-dependence of the extended DoF were in excellent agreement with theoretical predictions. These results provide a simple and broadly applicable approach to increase the throughput of existing nonlinear optical imaging methods for protein crystal screening.

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41

He, Wenhao, Bingyu Xue, Qi Qian, Shenye Chen, Zhengyi Fu, and Kun Wang. "Mineralization of Octacalcium Phosphate under Magnetic Field." Crystals 14, no. 5 (May 16, 2024): 463. http://dx.doi.org/10.3390/cryst14050463.

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The mineralization of octacalcium phosphate (OCP) crystals in gel media was studied in the presence of a magnetic field. OCP crystal growth was found to be dependent on mineralization temperature, mineralization time, and the magnetic field. Higher temperatures significantly reduced the mineralization time, which is crucial for directional growth of OCP crystals. The growth of OCP crystals was accelerated by the applied magnetic field, while OCP crystals generated in the presence of a magnetic field exhibited increased length and width of oriented growth. This study provides valuable insights into the influence of mineralization factors in bioprocessing-inspired manufacturing processes.

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42

Bravo, D., and F. J. López. "EPR and crystal-field analysis ofYb3+ions inBi4Ge3O12single crystals." Physical Review B 58, no. 1 (July 1, 1998): 39–42. http://dx.doi.org/10.1103/physrevb.58.39.

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Sette, F., B. Sinkovic, Y. J. Ma, and C. T. Chen. "Crystal-field splitting of core excitons in ionic crystals." Physical Review B 39, no. 15 (May 15, 1989): 11125–30. http://dx.doi.org/10.1103/physrevb.39.11125.

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Birkholz, Mario. "Crystal-field induced dipoles in heteropolar crystals I: Concept." Zeitschrift f�r Physik B Condensed Matter 96, no. 3 (September 1995): 325–32. http://dx.doi.org/10.1007/bf01313054.

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45

Wu, Xiao-Xuan, Wen-Chen Zheng, and Sheng Tang. "Studies Of The G Factor For Cr4+ Ion In Bi4ge3o12 Crystal From Crystal-Field And Charge-Transfer Mechanisms." Zeitschrift für Naturforschung A 59, no. 7-8 (August 1, 2004): 467–70. http://dx.doi.org/10.1515/zna-2004-7-809.

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The complete third-order perturbation formulas of the g factors g|| and g⊥ for 3d2 ions in tetragonal MX4 clusters have been obtained by a cluster approach. In these formulas, in addition to contributions to the g factors from the crystal-field mechanism in the crystal-field theory, the contributions from the charge-transfer mechanism are included. From these formulas, the g factors g|| and g⊥ for a Cr4+ ion in a Bi4Ge3O12 crystal are calculated. The results agree with the observed values. The calculated Δ gi(i = || or ⊥) value due to the charge-transfer is opposite in sign and about 20% greater than that due to the crystal-field mechanism. So, for the 3dn ions having a high valence in crystals, a reasonable explanation of the g factors should take both the crystal-field and charge-transfer mechanisms into account.

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46

Yang, Quanxin, Xiaojin Li, Hongliang Liu, Yingying Ren, and Pengfei Wu. "Field-induced transformation of ferroelectric domain states in KTN crystal." Chinese Optics Letters 19, no. 11 (2021): 111602. http://dx.doi.org/10.3788/col202119.111602.

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47

Yang, Wei-Qing, and Wen-Chen Zheng. "Spin-Hamiltonian Parameters of Gd3+ Ion in the Room Temperature Tetragonal Phase of BaTiO3." Zeitschrift für Naturforschung A 69, no. 10-11 (November 1, 2014): 606–10. http://dx.doi.org/10.5560/zna.2014-0057.

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AbstractThe spin-Hamiltonian parameters (g factors g||, g⊥, and zero-field splittings b02 , b04 , b44 , b06 , b46 ) of the 4f7 Gd3+ ion in the tetragonal phase of a BaTiO3 crystal are calculated through the diagonalization (of energy matrix) method based on the one-electron crystal field mechanism. In the calculations, the crystal field parameters are estimated from the superposition model with the structural data of the studied crystal. It is found that by using three adjustable intrinsic parameters Āk(R0) (k=2, 4, 6) in the superposition model, the seven calculated spin-Hamiltonian parameters are in good agreement with the experimental values, suggesting that the diagonalization method based on one-electron crystal field mechanism is effective in the studies of spin-Hamiltonian parameters for 4f7 ions in crystals.

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48

Koizumi, H., S. Uda, K. Fujiwara, M. Tachibana, K. Kojima, and J. Nozawa. "Improvement of crystal quality for tetragonal hen egg white lysozyme crystals under application of an external alternating current electric field." Journal of Applied Crystallography 46, no. 1 (January 17, 2013): 25–29. http://dx.doi.org/10.1107/s0021889812048716.

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X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white lysozyme (HEWL) crystals grown with and without application of an external alternating current (AC) electric field, and then the crystal quality was assessed by the FWHMs of each rocking-curve profile. The FWHMs for HEWL crystals grown with an external electric field were smaller than those for crystals grown without. In particular, the average FWHM for the 12 12 0 reflection with an external electric field (0.0034°) was significantly smaller than that without (0.0061°). This indicates that the crystal quality of HEWL crystals was improved by application of the external AC electric field. This crystallization technique can be expected to enhance the resolution of protein molecule structure analysis by X-ray diffraction.

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Pyzer-Knapp, Edward O., Hugh P. G. Thompson, and Graeme M. Day. "An optimized intermolecular force field for hydrogen-bonded organic molecular crystals using atomic multipole electrostatics." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 72, no. 4 (July 16, 2016): 477–87. http://dx.doi.org/10.1107/s2052520616007708.

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We present a re-parameterization of a popular intermolecular force field for describing intermolecular interactions in the organic solid state. Specifically we optimize the performance of the exp-6 force field when used in conjunction with atomic multipole electrostatics. We also parameterize force fields that are optimized for use with multipoles derived from polarized molecular electron densities, to account for induction effects in molecular crystals. Parameterization is performed against a set of 186 experimentally determined, low-temperature crystal structures and 53 measured sublimation enthalpies of hydrogen-bonding organic molecules. The resulting force fields are tested on a validation set of 129 crystal structures and show improved reproduction of the structures and lattice energies of a range of organic molecular crystals compared with the original force field with atomic partial charge electrostatics. Unit-cell dimensions of the validation set are typically reproduced to within 3% with the re-parameterized force fields. Lattice energies, which were all included during parameterization, are systematically underestimated when compared with measured sublimation enthalpies, with mean absolute errors of between 7.4 and 9.0%.

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Diao, Xin-Feng, Li-Ke Gao, Yu Xie, Tian-Yu Tang, and Yan-Lin Tang. "Ferromagnetic and Antiferromagnetic Properties of Perovskite Solar Cell Materials." Journal of Nanoelectronics and Optoelectronics 16, no. 3 (March 1, 2021): 434–43. http://dx.doi.org/10.1166/jno.2021.2943.

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This paper provides an intriguing electronic and magnetic properties of the Perovskite solar cell materials (MAPbI3, CsGeI3) which are analyzed by using density functional theory, where MAPbI3 is the abbreviation of CH3NH3PbI3. Herein, we mainly discuss the influence of ferromagnetism and antiferromagnetism on the crystal structure, band gap and electronic density of states of perovskite (MAPbI3) (CsGeI3). The magmom values of the applied magnetic field are from −6 μB to 6 μB, respectively (The negative sign here represents the opposite direction of the original magnetic field). The lattice parameters and volume of the crystal under different magnetic fields are obtained. It can be seen from the free energy that the stability of the crystal is compared with non-magnetic field, when the applied magnetic fields are at 4 μB and 5 μB, the free energy of the crystal is the lowest and its relative stability is better. At the same time, the magnetic field of CsGeI3 increases from −5 μB to 5 μB. The results show that the density of states of CsGeI3 moves towards the direction of higher energy, and the change of MAPbI3 crystal is more obvious. Similarly, we should pay attention to that when applying a magnetic field to the crystals, it is found that the band gap of both MAPbI3 and CsGeI3 decreases obviously after increasing the magnetic field, which avoids the situation of spin up and spin down overlap of MAPbI3, which is helpful to adjust the band gap size. From the perspective of crystal spectral absorption characteristics, when considering the ferromagnetic effect on CsGeI3 with the magnetic moment of a single atom is set to (1 μB, 2 μB, 3 μB, 4 μB, 5 μB, 6 μB), the width of absorption spectrum tends to decrease, but the impact on MAPbI3 is small.

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Journal articles on the topic 'Crystal field'

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