Log in

Relevant bibliographies by topics / Incommensurate / Journal articles

To see the other types of publications on this topic, follow the link: Incommensurate.

Journal articles on the topic 'Incommensurate'

Author: Grafiati

Published: 4 June 2021

Last updated: 20 February 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Incommensurate.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Kubli, Martin, Matteo Savoini, Elsa Abreu, Bulat Burganov, Gabriel Lantz, Lucas Huber, Martin Neugebauer, et al. "Kinetics of a Phonon-Mediated Laser-Driven Structural Phase Transition in Sn2P2Se6." Applied Sciences 9, no. 3 (February 4, 2019): 525. http://dx.doi.org/10.3390/app9030525.

Full text

Abstract:

We investigate the structural dynamics of the incommensurately modulated phase of Sn 2P 2Se 6 by means of time-resolved X-ray diffraction following excitation by an optical pump. Tracking the incommensurable distortion in the time domain enables us to identify the transport effects leading to a complete disappearance of the incommensurate phase over the course of 100 ns. These observations suggest that a thin surface layer of the high-temperature phase forms quickly after photo-excitation and then propagates into the material with a constant velocity of 3.7 m/s. Complementary static structural measurements reveal previously unreported higher-order satellite reflection in the incommensurate phase. These higher-order reflections are attributed to cubic vibrational terms in the Hamiltonian.

APA, Harvard, Vancouver, ISO, and other styles

2

Caracas, Razvan. "A database of incommensurate phases." Journal of Applied Crystallography 35, no. 1 (January 22, 2002): 120–21. http://dx.doi.org/10.1107/s0021889801017083.

Full text

Abstract:

A database of incommensurate phases is currently available at http://www.mapr.ucl.ac.be/~crystal/index.html. The present database offers a fast direct retrieval system for structural, physical and bibliographical data of incommensurate phases. The database contains data about inorganic, non-composite, non-magnetic and non-superconducting incommensurate phases only. Classification is according to the physical mechanisms responsible for the incommensurate phase transition. The main classes of incommensurate phases thus obtained are: theA2BX4dielectrics family, zone-centre lock-in transition phases, cooperative Jahn–Teller incommensurates, tetragonal tungsten bronzes, charge-density wave systems and miscellaneous incommensurate phases. The latter class, because of the lack of available data, is classified on a chemical basis in several subclasses: silicates, perovskites, Mn-bearing oxides, other oxides, group VI compounds, intermetallics and other compounds. The database contains a brief description of the main physical, chemical and structural features of each phase, as stated in the literature. This description is very material- and bibliography-dependent and it is preceded by the phase transition sequence.

APA, Harvard, Vancouver, ISO, and other styles

3

Stokes, Harold T., and Branton J. Campbell. "Enumeration and tabulation of magnetic (3+d)-dimensional superspace groups." Acta Crystallographica Section A Foundations and Advances 78, no. 4 (June 28, 2022): 364–70. http://dx.doi.org/10.1107/s2053273322003898.

Full text

Abstract:

A magnetic superspace group (MSSG) simultaneously constrains both the magnetic and non-magnetic (e.g. displacive, occupational, rotation and strain) degrees of freedom of an incommensurately modulated magnetic crystal. We present the first enumeration and tabulation of all non-equivalent (3+d)-dimensional magnetic superspace groups for d = 1, 2 and 3 independent incommensurate modulations, along with a number, symbol and reference setting for each group. We explain the process for generating an exhaustive set of inequivalent magnetic superspace groups, describe several examples, and show how the tables can be accessed via the ISO(3+d)D interface within the ISOTROPY Software Suite. We recommend that published incommensurate magnetic structures indicate a magnetic superspace-group number and symbol from these tables, as well as the transformation matrix from the published group setting to the reference setting used in these tables.

APA, Harvard, Vancouver, ISO, and other styles

4

Sastry, V. S. S., K. Venu, S. Uma Maheswari, and R. K. Subramanian. "NQR Study of Dynamics in Incommensurate Phases." Zeitschrift für Naturforschung A 55, no. 1-2 (February 1, 2000): 281–90. http://dx.doi.org/10.1515/zna-2000-1-250.

Full text

Abstract:

Dynamic processes in solids exhibiting structurally incommensurate phases are briefly reviewed, and the application of NMR and NQR is discussed. The unique utility of these methods, - arising due to, on one hand, the microscopic resonant nature of the probe used and, on the other, the presence of periodic, though incommensurable, structure - , is brought out by presenting recent results in a prototype system (Rb2ZnCl4) in the presence of randomly quenched disorder. In particular, the interesting new methodology of measuring, by analysing NQR spin echo modulation, ultra-slow diffusion like collective motions of ensembles of atoms in the presence of pinning effects due to disorder is illustrated with new results.

APA, Harvard, Vancouver, ISO, and other styles

5

Bertaut, E. F. "Commensurate — Incommensurate." Crystallography Reviews 2, no. 3 (June 1990): 107–27. http://dx.doi.org/10.1080/08893119008032952.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Zaretskii, V. V., and O. Kh Khasanov. "Incommensurate crystals." Phase Transitions 16, no. 1-4 (June 1989): 457–61. http://dx.doi.org/10.1080/01411598908245721.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Abakumov, Artem. "Combining powder diffraction with TEM for solving modulated structures." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C135. http://dx.doi.org/10.1107/s2053273314098647.

Full text

Abstract:

In many materials competing interactions of different nature may give rise to incommensurate modulations causing extreme structure complexity. Ab initio solution of the modulated structures even with using high quality synchrotron X-ray and/or neutron powder diffraction data appears to be a very challenging problem due to weakness of the satellite reflections, ambiguity in the determination of the modulation vector(s) and superspace symmetry and difficulties in building the initial model for further Rietveld refinement. These problems can be resolved or, at least, mitigated if the diffraction, imaging and spectroscopic advanced transmission electron microscopy techniques are combined with the analysis of powder diffraction data. Complete reconstruction of the reciprocal space, structure solution using quasi-kinematical electron diffraction data, mapping projected scattering density in the unit cell, visualization of the light atoms, displacive and occupational ordering, mapping chemical composition and coordination number can be utilized to reveal the nature of incommensurate modulations and construct the reliable model for the refinement from powder diffraction data. The benefit of the strategy of combining the powder diffraction data with the reciprocal and real space information obtained using aberration-corrected scanning transmission electron microscopy will be illustrated on the examples of the transition metal oxides: Li3xNd2/3-xTiO3 perovskites with frustrated incommensurately modulated octahedral tilting pattern [1]; perovskites (Bi,Pb)1-xFe1+xO3-y, modulated by crystallographic shear planes [2]; CaGd2(1-x)Eu2x(MoO4)4(1-y)(WO4)4y scheelites with incommensurately modulated ordering of cation vacancies [3].

APA, Harvard, Vancouver, ISO, and other styles

8

Palatinus, Lukáš, Michal Dušek, Robert Glaum, and Brahim El Bali. "The incommensurately and commensurately modulated crystal structures of chromium(II) diphosphate." Acta Crystallographica Section B Structural Science 62, no. 4 (July 12, 2006): 556–66. http://dx.doi.org/10.1107/s0108768106010238.

Full text

Abstract:

Chromium(II) diphosphate, Cr2P2O7, has an incommensurately modulated structure at ambient conditions with a = 7.05, b = 8.41, c = 4.63 Å, β = 108.71° and q = (−0.361, 0, 0.471). It undergoes a phase transition towards a commensurate structure with a commensurate q vector, q = (−{1\over 3}, 0, ½), at Tc = 285 K. The incommensurate structure has been solved by the charge-flipping method, which yielded both the basic positions of the atoms and the shapes of their modulation functions. The structure model for the commensurate structure was derived directly from the incommensurate structure. The structure analysis shows that the modulation leads to a change of the coordination of the Cr2+ ions from distorted octahedra in the average structure towards a sixfold coordination in the form of a more regular octahedron and a fivefold coordination in the form of a square pyramid. The fivefold and sixfold coordination polyhedra alternate along the lattice direction a with the pattern 5-6-5 5-6-5 in the commensurate structure. In the incommensurate structure this pattern is occasionally disturbed by a 5-6-5-5 motif. Both structures can be described in superspace using the same superspace group and a similar modulated structure model. The same superspace model can also be used for the low-temperature phases of other metal diphosphates with the thortveitite stucture type at high temperature. Their low-temperature structures can be obtained from the superspace model by varying the q vector and the origin in the internal dimension t 0.

APA, Harvard, Vancouver, ISO, and other styles

9

Xu, Z., Dwight Viehland, and D. A. Payne. "An incommensurate-commensurate phase transformation in antiferroelectric tin-modified lead zirconate titanate." Journal of Materials Research 10, no. 2 (February 1995): 453–60. http://dx.doi.org/10.1557/jmr.1995.0453.

Full text

Abstract:

Antiferroelectric tin-modified lead zirconate titanate ceramics (PZST), with 42 at. % Sn and 4 at. % Ti, were studied by hot- and cold-stage transmission electron microscopy and selected area electron diffraction techniques. The previously reported tetragonal antiferroelectric state is shown to be an incommensurate orthohombic state. Observations revealed the existence of incommensurate 1/x 〈110〉 superlattice reflections below the temperature of the dielectric maximum. The modulation wavelength for this incommensurate structure was found to be metastably locked-in near and below room temperature. An incommensurate-commensurate orthorhombic antiferroelectric transformation was then observed at lower temperatures. However, an intermediate condition was observed over a relatively wide temperature range which was characterized by an intergrowth of 〈110〉 structural modulations, which was strongly diffuse along the 〈110〉. These structural observations were correlated with dispersion in the dielectric properties in the same temperature range. No previous reports of an incommensurate orthorhombic antiferroelectric state or an incommensurate-commensurate orthorhombic antiferroelectric transformation are known to exist.

APA, Harvard, Vancouver, ISO, and other styles

10

Hejny, C., and L. Bindi. "Low-temperature behaviour of K2Sc[Si2O6]F: determination of the lock-in phase and its relationships with fresnoite- and melilite-type compounds." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 73, no. 5 (September 19, 2017): 923–30. http://dx.doi.org/10.1107/s2052520617010241.

Full text

Abstract:

K2Sc[Si2O6]F exhibits, at room temperature, a (3 + 2)-dimensional incommensurately modulated structure [a= 8.9878 (1),c= 8.2694 (2) Å,V= 668.01 (2) Å3; superspace groupP42/mnm(α,α,0)000s(−α,α,0)0000] with modulation wavevectorsq1= 0.2982 (4)(a* +b*) andq2= 0.2982 (4)(−a* +b*). Its low-temperature behaviour has been studied by single-crystal X-ray diffraction. Down to 45 K, the irrational component α of the modulation wavevectors is quite constant varying from 0.2982 (4) (RT), through 0.2955 (8) (120 K), 0.297 (1) (90 K), 0.298 (1) (75 K), to 0.299 (1) (45 K). At 25 K it approaches the commensurate value of one-third [i.e.0.332 (3)]: thus indicating that the incommensurate–commensurate phase transition takes place between 45 K and 25 K. The commensurate lock-in phase of K2Sc[Si2O6]F has been solved and refined with a 3 × 3 × 1 supercell compared with the tetragonal incommensurately modulated structure stable at room temperature. This corresponds to a 3 × 1 × 3 supercell in the pseudo-orthorhombic monoclinic setting of the low-temperature structure, space groupP2/m, with lattice parametersa= 26.786 (3),b= 8.245 (2)c= 26.824 (3) Å, β = 90.00 (1)°. The structure is a mixed tetrahedral–octahedral framework composed of chains of [ScO4F2] octahedra that are interconnected by [Si4O12] rings with K atoms in fourfold to ninefold coordination. Distorted [ScO4F2] octahedra are connected to distorted Si tetrahedra to form octagonal arrangements closely resembling those observed in the incommensurate structure of fresnoite- and melilite-type compounds.

APA, Harvard, Vancouver, ISO, and other styles

11

Saint-Grégoire, P. "Ferroelastic Incommensurate Phases." Key Engineering Materials 101-102 (March 1995): 237–84. http://dx.doi.org/10.4028/www.scientific.net/kem.101-102.237.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Van Smaalen, Sander. "Incommensurate crystal structures." Crystallography Reviews 4, no. 2 (January 1995): 79–202. http://dx.doi.org/10.1080/08893119508039920.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Blinc, R., S. Žumer, O. Jarh, and F. Milia. "T2in incommensurate systems." Physical Review B 40, no. 16 (December 1, 1989): 10687–93. http://dx.doi.org/10.1103/physrevb.40.10687.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

McNamee, Sheila. "Bridging Incommensurate Discourses." Theory & Psychology 13, no. 3 (June 2003): 387–96. http://dx.doi.org/10.1177/0959354303013003005.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Hill, J. P., A. T. Boothroyd, N. H. Andersen, E. Brecht, and Th Wolf. "Incommensurate magnetism inPrBa2Cu3O6.92." Physical Review B 58, no. 17 (November 1, 1998): 11211–14. http://dx.doi.org/10.1103/physrevb.58.11211.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Jacobs, A. E., and David Mukamel. "Universal incommensurate structures." Journal of Statistical Physics 58, no. 3-4 (February 1990): 503–10. http://dx.doi.org/10.1007/bf01112759.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Antoranz, J. C., and Hazime Mori. "Intermittent incommensurate chaos." Physica D: Nonlinear Phenomena 16, no. 2 (June 1985): 184–202. http://dx.doi.org/10.1016/0167-2789(85)90057-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Patel, Prem, Li Chen, S. Sabol Keast, Mary E. Neubert, and Satyendra Kumar. "Incommensurate Smectic Phases?" Liquid Crystals Today 2, no. 1 (March 1992): 3. http://dx.doi.org/10.1080/13583149208628588.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Morelli, Rose, and M. B. Walker. "Novel mechanism for the incommensurate-to-incommensurate phase transition inNbTe4." Physical Review Letters 62, no. 13 (March 27, 1989): 1520–23. http://dx.doi.org/10.1103/physrevlett.62.1520.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Chen, Z. Y., and M. B. Walker. "Superspace symmetry modes and incommensurate-to-incommensurate phase transition inNbTe4." Physical Review B 40, no. 13 (November 1, 1989): 8983–94. http://dx.doi.org/10.1103/physrevb.40.8983.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Elding-Pontén, M., L. Stenberg, S. Lidin, G. Madariaga, and J. M. Pérez-Mato. "Structure of Mn8Sn5." Acta Crystallographica Section B Structural Science 53, no. 3 (June 1, 1997): 364–72. http://dx.doi.org/10.1107/s0108768197000682.

Full text

Abstract:

The title compound crystallizes as a slightly incommensurate modulation of the B8-type structure. In a basic NiAs structure, ∼60% of the trigonal pyramidal interstices are filled with Mn atoms in an ordered manner. The highest corresponding commensurate space group is Pbnm (Pnma, No. 62) with the cell parameters a = 21.9114 (4), b: 7.6003 (5), c = 5.5247 (5) Å. The four-dimensional superspace group of the incommensurate structure is Cmcm(α00)0s0 (No. 63.8), with the conventional setting Amam(00γ)0s0. The cell parameters for this incommensurate cell are a = 382 (1), b = 7.600 (2), c = 5.525 (2) Å, q = [0.616 (5), 0, 0]. The structural refinements were carried out on a multiply twinned specimen. The R-factors were 0.037 for the incommensurate refinement and 0.046 for one commensurate approximation. The refinements unambiguously show that the modulation is caused by the step-like modulation of one Mn site, which is accompanied by small displacive modulations of the basic lattice. The incommensurate nature of the modulation is manifested in a slight splitting of fifth-order satellites, visible in electron diffraction.

APA, Harvard, Vancouver, ISO, and other styles

22

Aizu, Kêitsiro. "Twofold Incommensurate Phase as Analogs of Semicommensurate Phases. On the Transitions [Prototypic→Ordinarily (or Onefold) Incommensurate →Twofold Incommensurate]." Journal of the Physical Society of Japan 55, no. 5 (May 15, 1986): 1663–70. http://dx.doi.org/10.1143/jpsj.55.1663.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

de Boissieu, Marc. "Phonon and phasons : from incommensurate phases to quasicrystals." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C9. http://dx.doi.org/10.1107/s2053273314099902.

Full text

Abstract:

Aperiodic crystals are long range ordered phases, which lack translational symmetry. They encompass incommensurately modulated phases, incommensurate composites phases and quasicrystals (1). Whereas their atomic structure is now well understood, even for the case of quasicrystals, the understanding of their physical properties remains a challenging problem. In particular, because of the aperiodic long range order, the lattice dynamics present a specific behavior. In particular, it can be shown theoretically that besides phonon, a supplementary excitation exits in all aperiodic phases named phason. Phason modes arise from the degeneracy of the free energy of the system with respect to a phase shift and are always diffusive modes (1). After a general introduction on the different class of aperiodic crystals, we will illustrate experimental results on phason modes. We will in particular demonstrate that these phason modes lead to a flexibility of the structure that might have important consequences for physical properties. We will also discuss their importance for the understanding of stabilizing mechanisms that lead to the long-range aperiodic order.

APA, Harvard, Vancouver, ISO, and other styles

24

RUSTAMOV, K. A., and B. R. GADJIEV. "THEORETICAL MODEL FOR THE HIGH-FREQUENCY DYNAMICAL SUSCEPTIBILITY IN THE IMPROPER SEGNETOELECTRICS." Modern Physics Letters B 07, no. 20 (August 30, 1993): 1335–42. http://dx.doi.org/10.1142/s0217984993001387.

Full text

Abstract:

Description of the temperature and frequency dependences of the dynamical susceptibility in improper segnetoelectrics in the incommensurate phase near the incommensurate–commensurate phase transition is presented. The used model is based on the theory of three interacting nonlinear oscillators.

APA, Harvard, Vancouver, ISO, and other styles

25

Morozov, Vladimir, Katrien Meert, Philippe Smet, Dirk Poelman, Artem Abakumov, and Joke Hadermann. "Incommensurate modulated structures and luminescence in scheelites." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C177. http://dx.doi.org/10.1107/s2053273314098222.

Full text

Abstract:

Scheelite (CaWO4) related compounds (A',A'')n[(B',B'')O4]m with B', B''=W and/or Mo are promising new materials for red phosphors in pc-WLEDs (phosphor-converted white-light-emitting-diode) and solid-state lasers. Scheelites can be prepared with a large concentration of vacancies in the A sublattice, giving compositions characterized by a (A'+A''):(B'O4+B''O4) ratio different from 1:1. The creation of cation vacancies in the scheelite-type framework and the ordering of A cations and vacancies are a new factor in controlling the scheelite-type structure and properties. Very often the substitution of Ca2+ by M+ and R3+ (R3+ = rare earth elements) in the scheelite-type structure leads to switching the structure from 3D to (3+n)D (n = 1,2) regime. The creation and ordering of A-cation vacancies and the effect of cation substitutions in the scheelite-type framework are investigated as a factor controlling the scheelite-type structure and luminescent properties of CaGd2(1-x)Eu2x(MoO4)4(1-y)(WO4)4y (0≤x≤1, 0≤y≤1) solid solutions. Within this series all complex molybdenum oxides have (3+2)D incommensurately modulated structures with superspace group I41/a(α,β,0)00(-β,α,0)00, while the structures of all tungstates are (3+1)D incommensurately modulated with superspace group I2/b(αβ0)00. In both cases the modulation arises due to cation-vacancy ordering at the A site. The replacement of the smaller Gd3+ by the larger Eu3+ at the A-sublattice does not affect the nature of the incommensurate modulation, but an increasing replacement of Mo6+ by W6+ switches the modulation from (3+2)D to (3+1)D regime. Acknowledgement. This research was supported by FWO (project G039211N, Flanders Research Foundation) and Russian Foundation for Basic Research (Grants 11-03-01164, and 12-03-00124).

APA, Harvard, Vancouver, ISO, and other styles

26

Guo, Ru, and Zhen-qing Yang. "The origin of the incommensurate phase and the incommensurate-commensurate transition." Ferroelectrics 66, no. 1 (February 1986): 189–94. http://dx.doi.org/10.1080/00150198608227884.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Stöger, Berthold. "Symmetry reduction in thortveitites: incommensurability and polytypism." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C182. http://dx.doi.org/10.1107/s2053273314098179.

Full text

Abstract:

For many years periodicity was the defining property of crystalline materials. The discovery of numerous aperiodic materials like incommensurately modulated phases or quasi-crystals led to a paradigm shift and since 1992 crystallinity is defined by the IUCr via the discreteness of the diffraction pattern [1]. A different class of materials lacking periodicity in three dimensions, albeit following strict building principles, are polytypes. Polytypes are composed of modules that can be arranged in different but energetically similar ways. On the example of the thortveitite family of compounds it will be shown that these seemingly disparate phenomena can be linked to the same underlying cause, namely symmetry reduction. Many bivalent transition metal diphosphates(V), diarsenates(V) and divanadates(V) of general formula M2X2O7 (X=P, As, V) crystallize in the thortveitite structure type. The high temperature β-M2X2O7 phases feature one crystallographically unique X2O7 group located on a centre of inversion. Due to the unfavourable X-O-X angle of 1800these phases transform on cooling into lower symmetry structures. Thus, numerous superstructures based on the thortveitite aristotype have been described. Incommensurate structures can be considered as superstructures with symmetry reduction by an index of ∞. The first example in the thortveitite family was described by Palatinus et al. [2]. Since then we found several other incommensuarte thortveitites with varying modulation functions and phase-transition behaviour. If the symmetry reduction leads to layers with different local symmetry, the resulting structures are order-disorder (OD) polytypes [3], resulting in twinning or diffuse scattering. In (Co,Ni)2As2O7 both features, incommensurate modulation and systematic twinning, are combined. An overview of the crystal-chemistry and the complex phase-transition behaviour of the incommensurately modulated and/or polytypic thortveitite phases will be given.

APA, Harvard, Vancouver, ISO, and other styles

28

Li, Yang, Zheng-Hua Wan, and Hai-Fu Fan. "MIMS: a program for measuring four-dimensional Fourier maps of incommensurate modulated structures." Journal of Applied Crystallography 32, no. 5 (October 1, 1999): 1017–20. http://dx.doi.org/10.1107/s0021889899006937.

Full text

Abstract:

The programMIMS(measuring incommensurate modulated structures) has been written for the determination of structural parameters of incommensurate one-dimensionally modulated structures by an automatic search routine on four-dimensional Fourier maps. Test results show that the program works accurately and efficiently.

APA, Harvard, Vancouver, ISO, and other styles

29

Gągor, Anna. "Phase transitions in ferroelectric 4-aminopyridinium tetrachloroantimonate(III) – revisited." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 74, no. 2 (March 21, 2018): 217–25. http://dx.doi.org/10.1107/s2052520618003669.

Full text

Abstract:

New X-ray diffraction studies on the crystal structure of ferroelectric [4-NH2C5H4NH][SbCl4] indicate that in the broad temperature range from 240 to 304 K covering the three intermediate phases, the crystal structure is modulated. Phase II is incommensurately modulated with modulation vectorq= βb*, β varying from 0.60 to 0.66 and monoclinicC2/c(0β0)s0 superspace group. Ferroelectric phase III is commensurate withq= 2\over 3b*andCc(0β0)0 symmetry. Polar phase IV is incommensurately modulated with β varying from 0.66 to 0.70 andCc(0β0)0 superspace group. In all phases only first-order satellites are observed along theb*direction. Two types of periodic deformation are present in the structure of modulated phases. The 4-aminopyridinium cations are subjected to occupation modulation whereas [SbCl4]−nchains are displacively modulated. The paraelectric–ferroelectric phase transition is an example of the incommensurate–commensurate transition of the lock-in type. A new mechanism for this transformation is proposed.

APA, Harvard, Vancouver, ISO, and other styles

30

Wang, Weiqian, Yuanhua Qiao, Jun Miao, and Lijuan Duan. "Dynamic Analysis of Fractional-Order Recurrent Neural Network with Caputo Derivative." International Journal of Bifurcation and Chaos 27, no. 12 (November 2017): 1750181. http://dx.doi.org/10.1142/s0218127417501814.

Full text

Abstract:

In this paper, fractional-order recurrent neural network models with Caputo Derivative are investigated. Firstly, we mainly focus our attention on Hopf bifurcation conditions for commensurate fractional-order network with time delay to reveal the essence that fractional-order equation can simulate the activity of neuron oscillation. Secondly, for incommensurate fractional-order neural network model, we prove the stability of the zero equilibrium point to show that incommensurate fractional-order neural network still converges to zero point. Finally, Hopf bifurcation conditions for the incommensurate fractional-order neural network model are first obtained using bifurcation theory based on commensurate fractional-order system.

APA, Harvard, Vancouver, ISO, and other styles

31

Schmid, Siegbert, Ray L. Withers, Deborah Corker, and Pierre Baules. "Towards a unified description of the AMOB2O5 (A = K, Rb, Cs, Tl; M = Nb, Ta) family of compounds." Acta Crystallographica Section B Structural Science 56, no. 4 (August 1, 2000): 558–64. http://dx.doi.org/10.1107/s0108768100002871.

Full text

Abstract:

Single-crystal X-ray diffraction data (Mo Kα radiation) are used to re-refine the structure of RbNbOB2O5, rubidium niobium oxo pyroborate. The structure is refined as an incommensurate modulated structure with superspace group symmetry Pmn21(0,0.4,0)s and lattice parameters a = 7.406 (2), b = 3.939 (2) and c = 9.475 (2) Å. Refinement on 3242 unique reflections converged to R = 0.031, while a previous conventional superstructure refinement led to R = 0.090. This lowering of the R factor goes hand-in-hand with a substantial reduction in the number of refined parameters. The refinement strongly suggests that the structure is effectively incommensurately modulated, despite an apparently rational magnitude of the primary modulation wavevector and overlap of satellite reflections.

APA, Harvard, Vancouver, ISO, and other styles

32

de Boissieu, Marc. "Ted Janssen and aperiodic crystals." Acta Crystallographica Section A Foundations and Advances 75, no. 2 (February 6, 2019): 273–80. http://dx.doi.org/10.1107/s2053273318016765.

Full text

Abstract:

This article reviews some of Ted Janssen's (1936–2017) major contributions to the field of aperiodic crystals. Aperiodic crystals are long-range ordered structures without 3D lattice translations and encompass incommensurately modulated phases, incommensurate composites and quasicrystals. Together with Pim de Wolff and Aloysio Janner, Ted Janssen invented the very elegant theory of superspace crystallography that, by adding a supplementary dimension to the usual 3D space, allows for a deeper understanding of the atomic structure of aperiodic crystals. He also made important contributions to the understanding of the stability and dynamics of aperiodic crystals, exploring their fascinating physical properties. He constantly interacted and collaborated with experimentalists, always ready to share and explain his detailed understanding of aperiodic crystals.

APA, Harvard, Vancouver, ISO, and other styles

33

Ng, Yong Xian, Chang Phang, Jian Rong Loh, and Abdulnasir Isah. "Analytical solutions of incommensurate fractional differential equation systems with fractional order $ 1 < \alpha, \beta < 2 $ via bivariate Mittag-Leffler functions." AIMS Mathematics 7, no. 2 (2022): 2281–317. http://dx.doi.org/10.3934/math.2022130.

Full text

Abstract:

<abstract><p>In this paper, we derive the explicit analytical solution of incommensurate fractional differential equation systems with fractional order $ 1 < \alpha, \beta < 2 $. The derivation is extended from a recently published paper by Huseynov et al. in <sup>[<xref ref-type="bibr" rid="b1">1</xref>]</sup>, which is limited for incommensurate fractional order $ 0 < \alpha, \beta < 1 $. The incommensurate fractional differential equation systems were first converted to Volterra integral equations. Then, the Mittag-Leffler function and Picard's successive approximations were used to obtain the analytical solution of incommensurate fractional order systems with $ 1 < \alpha, \beta < 2 $. The solution will be simplified via some combinatorial concepts and bivariate Mittag-Leffler function. Some special cases will be discussed, while some examples will be given at the end of this paper.</p></abstract>

APA, Harvard, Vancouver, ISO, and other styles

34

Dolinšek, J., and R. Blinc. "A Note on the 14N Electric Field Gradient Notizen: Tensors in Incommensurate [N(CH3)4]2ZnCl4." Zeitschrift für Naturforschung A 42, no. 3 (March 1, 1987): 305–6. http://dx.doi.org/10.1515/zna-1987-0318.

Full text

Abstract:

The 14N electric field gradient tensors of [N(CH3)4]2ZnCl4 have been re-determined in the paraelectric phase at 26 °C and in the incommensurate phase at 16 °C. The results in the incommensurate phase show the “non-local” nature of the 14N EFG tensor interaction.

APA, Harvard, Vancouver, ISO, and other styles

35

Michiue, Yuichi, Akiji Yamamoto, Mitsuko Onoda, Akira Sato, Takaya Akashi, Hisanori Yamane, and Takashi Goto. "Incommensurate crystallographic shear structure of Ba x Bi2 − 2x Ti4 − x O11 − 4x (x = 0.275)." Acta Crystallographica Section B Structural Science 61, no. 2 (March 16, 2005): 145–53. http://dx.doi.org/10.1107/s0108768105001655.

Full text

Abstract:

The title compound generates diffraction patterns which are indexable within the framework of the higher-dimensional description of incommensurate structures. However, it is difficult to discriminate the main reflections from the satellite ones. This paper has clarified that the structure can be treated as a strongly modulated structure with sawtooth-like modulation functions and is classified as an incommensurate crystallographic shear (CS) structure. The structure consists of domains isostructural to β-Bi2Ti4O11 and domain boundaries composed of TiO6 octahedra. Ba and Bi ions are accommodated in the cavities between TiO6 octahedra in the domain. Domain boundaries are aperiodically inserted, in contrast to the usual CS structures, forming an incommensurate structure.

APA, Harvard, Vancouver, ISO, and other styles

36

Doling, G. "Incommensurate Phases of Quartz." Japanese Journal of Applied Physics 24, S2 (January 1, 1985): 153. http://dx.doi.org/10.7567/jjaps.24s2.153.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Rusu, Dorin, Jonathan J. P. Peters, Thomas P. A. Hase, James A. Gott, Gareth A. A. Nisbet, Jörg Strempfer, Daniel Haskel, et al. "Ferroelectric incommensurate spin crystals." Nature 602, no. 7896 (February 9, 2022): 240–44. http://dx.doi.org/10.1038/s41586-021-04260-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Terasaki, Osamu, and Denjiro Watanabe. "Commensurate and incommensurate superstructures." Bulletin of the Japan Institute of Metals 24, no. 12 (1985): 979–83. http://dx.doi.org/10.2320/materia1962.24.979.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Hayden, S. M., G. H. Lander, J. Zarestky, P. J. Brown, C. Stassis, P. Metcalf, and J. M. Honig. "Incommensurate magnetic correlations inLa1.8Sr0.2NiO4." Physical Review Letters 68, no. 7 (February 17, 1992): 1061–64. http://dx.doi.org/10.1103/physrevlett.68.1061.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Graetsch, H. "Incommensurate phases of tridymite." Acta Crystallographica Section A Foundations of Crystallography 52, a1 (August 8, 1996): C315. http://dx.doi.org/10.1107/s010876739608693x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Herbert, James D. "Courbet, Incommensurate and Emergent." Critical Inquiry 40, no. 2 (January 2014): 339–81. http://dx.doi.org/10.1086/674118.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Stöger, Berthold. "Incommensurate oxides and sulfides." Acta Crystallographica Section A Foundations and Advances 72, a1 (August 28, 2016): s98. http://dx.doi.org/10.1107/s2053273316098557.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Bao, Wei, P. G. Pagliuso, J. L. Sarrao, J. D. Thompson, Z. Fisk, J. W. Lynn, and R. W. Erwin. "Incommensurate magnetic structure ofCeRhIn5." Physical Review B 62, no. 22 (December 1, 2000): R14621—R14624. http://dx.doi.org/10.1103/physrevb.62.r14621.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Aubry, S., K. Fesser, and A. R. Bishop. "Locking to incommensurate structures." Ferroelectrics 66, no. 1 (February 1986): 151–67. http://dx.doi.org/10.1080/00150198608227882.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Lebedev, N. I., A. P. Levanyuk, and A. S. Sigov. "Defects in incommensurate structures." Ferroelectrics 78, no. 1 (February 1988): 145–50. http://dx.doi.org/10.1080/00150198808215899.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Nikšić, G., I. Kupčić, D. K. Sunko, and S. Barišić. "Incommensurate SDW in cuprates." Physica B: Condensed Matter 407, no. 11 (June 2012): 1799–802. http://dx.doi.org/10.1016/j.physb.2012.01.033.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Friedel, J., and P. G. de Gennes. "Friction between incommensurate crystals." Philosophical Magazine 87, no. 1 (January 2007): 39–49. http://dx.doi.org/10.1080/14786430600880751.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Jacobs, A. E. "The incommensurate phase of." Journal of Physics: Condensed Matter 8, no. 5 (January 29, 1996): 517–26. http://dx.doi.org/10.1088/0953-8984/8/5/002.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Levanyuk, A. P. "Fluxes in incommensurate crystals." Journal de Physique I 4, no. 9 (September 1994): 1353–64. http://dx.doi.org/10.1051/jp1:1994113.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Borisov, A. B., and V. V. Kiseliev. "Vortices in incommensurate structures." Solid State Communications 59, no. 7 (August 1986): 445–48. http://dx.doi.org/10.1016/0038-1098(86)90684-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!