Crystal Physical Properties Research Articles

Advances in computer modelling of mineral properties

The following six papers were presented at a meeting, held in September 1994, which reviewed some of the recent advances in the application of computational methods to mineralogy. Talks covered the developing and challenging field of ab initio quantum mechanical computations as well as new applications and insights afforded by the use and refinement of the more established methods of empirical simulation and modelling. The former attempt to solve Schrdinger's equation for the material in question, and in doing so determine the energy surface and electronic structure. The latter use parameterized interatomic potentials to describe the energy of interaction between pairs or groups of atoms, the parameters typically derived either by fitting to the results of quantum mechanical calculations of small clusters, or empirically determined from fitting to the known physical properties of crystals (e.g. to the elastic constants, structural parameters or dielectric constants). A certain rivalry and antipathy occasionally surfaces between computational theorists from either camp.

Kinetics of structural phase transition in semiconductors caused by redistribution of electrons on trapping levels

An approach is proposed for describing photostimulated phase transition kinetics. This approach takes into account the dynamics of the electron density on trapping levels in the semiconductor. A correlation between the abnormal physical properties of crystals and characteristics of the semiconducting subsystem is established.

Memory effects in incommensurate phase and kinetic of electronic subsystem

Abstract A new approach is proposed for describing memory effect and global hysteresis in incommensurate phase. This approach is to take account the dynamics of the nonuniform electron density in trapping levels in the semiconductor. A correlation between the abnormal physical properties of crystals and characteristics of semiconducting subsystem is established.

Indexing Powder Patterns from Relative Axial Dimensions

The usefulness of an X-ray powder diffraction data base, such as the one published by the International Centre for Diffraction Data, is largely dependent on continued additions of indexed powder patterns of single-phase materials of interest to data-base users. The single-phase character of a specimen is generally established by using known values of the unit cell constants to index all its powder pattern lines.In this manuscript we describe indexing procedures based on crystal data which provide only relative values of the cell dimensions, rather than the absolute values usually considered to be essential to the indexing process. To the best of our knowledge, the use of such data for indexing powder diffraction patterns has generally been overlooked or ignored by X-ray crystallographers. We refer to the large numbers of goniometric measurements of crystals which have been published both before, and since, the discovery of X-ray diffraction. These provide useful descriptions of chemical and physical properties of crystals as well as measurements of relative dimensions of unit cell axes. The latter are presented in the form of a/b, b/b and c/b, together with the interaxial angle or angles, if the cell is nonorthogonal.

Modern crystallography. IV. Physical properties of crystals. Springer series in solid state sciences 37 by L. A. Shuvalov

<i>Modern crystallography</i>. IV. <i>Physical properties of crystals</i>. <i>Springer series in solid state sciences</i> 37 by L. A. Shuvalov

A review of: “Modern crystallography IV. physical properties of crys tals.”

Abstract edited by l. a. shuvalov. springer-verlag, berlin, heidelberg, new york, 1988. 583 pp. 270 figs. dm 198. us $115.00

Interaction processes and a general thermodynamic analysis of various fields in crystals

Abstract The interaction processes of elastic, thermal, electric, magnetic, and optical fields in crystals are represented schematically by a pyramid-shaped interaction drawing. The macroscopic physical properties of crystals subjected to these fields are classified in five groups and a comprehensive thermodynamic treatment is presented based on the use of Gibbs free energy. The method is useful in analyzing nonlinear and multifunctional effects, in discussing relations between different interactions, and in the prediction of new phenomena.

The influence of point defects on selected properties of PbTio3crystals

Abstract Point defects exert an important influence on the physical properties of crystals. The presence of defects may cause colouration of crystals and increase in their electric conductivity making technical application of these crystals difficult or even impossible. In this paper several possibilities of point defects formation in PbTiO3 crystals are given. The presence of these defects may be associated both with nonstoichiometry and with impurities. The aim of these studies was to determine the technological conditions for obtaining high quality PbTiO3 single crystals. Crystals were obtained by the “flux” method from PbO-TiO2-B2O3 solution.

Dislocation-induced anomalies of physical properties of crystals near structural phase transitions

Abstract It is shown that in some crystals the dislocations may play the leading part in phase transition anomalies of sound velocity and absorption as well as in strong q-dependence of the anomalous contribution to the elastic light scatering intensity. Theoretical results are compared with the experimental data available.

Book reviews

Book reviews

Thermal and residual stresses of Czochralski-grown semiconducting material

The thermal stresses during pulling and the residual stresses after pulling in a Czochralski-grown semiconducting crystal are obtained analytically by using an isotropic thermoelastic model. It is assumed that a finite cylindrical crystal is withdrawn from a melt with a constant pulling rate, and the physical properties of crystal are independent of temperature. Moreover the problem is considered to be a quasi-stationary one. Numerical results show that the Biot number is a prime factor affecting the thermal and residual stresses. The differences between the models of the finite crystal and semi-infinite crystal are described. An explanation of the experimental results is attempted.

Physical Properties of Crystals – Their Representation by Tensors and Matrices

J F Nye 1985 Clarendon Press: Oxford University Press xvii + 329 pp price £15 (paperback) ISBN 0 19 851165 5 A review of a well-known and trusted work such as this is difficult. It is 28 years since Professor Nye's book first appeared in hardback form.

Physical properties of crystals: their representation by tensors and matricesby J. F. Nye

<i>Physical properties of crystals: their representation by tensors and matrices</i>by J. F. Nye

Book reviews

Abstract Principles of Electron Tunneling Spectroscopy. By E. L. Wolf. (Oxford and New York: Clarendon Press, 1985.) [Pp. xiii + 563 + subject index.] Price $60·00 hard cover. Strong and Ultrastrong Magnetic Fields and Their Applications. Edited by F. Herlach. (Berlin, Heidelberg, New York: Springer-Verlag, 1985.) [Pp. xii + 353 + subject index.] Price DM 138 hard cover. Absorption Processes on Semiconductor and Dielectric Surfaces I. By V. F. Kiselev and O. V. Krylov. (Berlin, Heidelberg, New York: Springer-Verlag, 1985.) [Pp. viii + 280 + subject index.] Price US $43·50 hard cover. Surface Crystallography. An Introduction to Low Energy Electron Diffraction. By L. J. Clarke. (Chichester, New York, Brisbane: J. Wiley & Sons, 1985.) [Pp. xiii + 325 + subject index.] Price $31·50 hard cover. Physical Properties of Crystals. Their representation by tensors and matrices. By J. F. Nye. (Oxford and New York: Clarendon Press, 1985.) [Pp. xvii + 322 + Author and Subject index.] Price $15·00 first soft cover edition (hard cover published in 1957.)

Determination of stress intensity factors by a method of holographic interferometry

i. L.V. Belokopytova and L. A. Fil'shtinskii, "The two-dimensional boundary problem of electroelasticity for a piezoelectric medium with notches," Prikl. Mat. Mekh., 43, No. i, 138-143 (1979). 2. L.V. Belokopytova, O. A. Ivanenko, and L. A. Fil'shtinskii, "Conjugate electrical and mechanical fields in piezoelastic bodies with notches or inclusions," in: The Dynamics and Strength of Machines [in Russian], No. 34, Kharkov (1981), p. 16-21. 3. W.P. Mason (ed.), Methods and Instruments for Ultrasonic Investigations. Physical Acoustics [Russian translation], Part A, Mir, Moscow (1968). 4. J. Nye, The Physical Properties of Crystals and Description of Them with the Use of Tensors and Matrices [Russia~ translation], IL, Moscow (1960). 5. N.I. Muskhelishvili, Singular Integral Equations [in Russian], Nauka, Moscow (1968). 6. L.A. Fil'shtinskii, "Longitudinal shear in an anisotropic medium with notches," Izv. Akad. Nauk SSSR, Mekh. Tverd. Tela, No. 4, 68-72 (1978).

Residual Stresses of Czochralski-Grown Crystal

The residual stresses in a Czochralski-grown crystal during and after pulling are obtained analytically by using a linear isotropic thermoelastic model. It is assumed that the physical properties of crystal are independent of temperature and that the crystal has a semi-infinite cylindrical shape as it is withdrawn from a melt with a constant pulling rate. Moreover the problem is considered to be a quasi-stationary one. Numerical results show that the Biot number is a prime factor affecting the residual stress and that the maximum residual stress occurs at the cylindrical surface when the Biot number is small and at the center of the crystal when it is large, respectively. An explanation for the experimental results is given.

On the Graphoanalytical Investigation of the Anisotropy of the Physical Properties of Crystals

On the Graphoanalytical Investigation of the Anisotropy of the Physical Properties of Crystals

Nature and singularities in the behavior of point defects in doped single crystals of A3B5 compounds

In conclusion, It should be stressed that, as follows from the experimental material considered, a characteristic singularity of semiconductor compounds is the stability of the metastable state which occurs during dissociation of the supersaturated solid solution under relatively small supersaturation conditions. The defects being formed here (interstitial atoms, vacancies, their distinct association in the form of complexes or coagulated particles, presegregated, etc.) exert considerable influence on the physical properties of crystals. In the general case, the crystal defectiveness depends on the kind and concentration of the doping impurity, the deviation of the composition from stoichiometry, and the ingot cooling mode during growth.

Coherent States and the Korteweg-de Vries Equation for a System of Interacting Phonons

has given physical explanation of their observation in terms of the strik­ ing properties of soliton solution associated with the Korteweg-de Vries equation, which has been derived on a continuum model of the one-dimensional anharmonic lattice. At the same time, he has emphasized that the conventional approach of the phonon description is not a suitable way to examine the recurrence phenomena observed by Fermi, Pasta and Ulam. Although vve appreciate the remarkable successes of the soliton concept £or various kinds of the nonlinear wave phenomena,'1 we can not completely discard the phonon picture in the description of physical properties of crystals. It would be worth while examining interrelationship between the soliton concept and the phonon description of the anharmonic lattice. Therefore, we have undertaken to derive the Korteweg-de Vries equation for the interacting phonon systems vvithin the scheme , of quantum mechanical approach. Since the soliton describes nonlinear propagation of a finite amplitude wave in the classical treatment, we e2):pect that the correspond­ mg quantum mechanical state must be a state in which a large number of phonons are excited. In the following sections, we illustrate that the coherent state representation of the system 41 enables us to derive, the Korteweg-de Vries equation for the in­ teracting phonons. In order to establish explicit correspondence between Zabusky's continuum approximation and the coherent state description of phonons, we derive

Vector nonlinear interactions of light waves in LiIO3 and K2S2O6 crystals

The influence of the physical properties of crystals on the noncollinear interaction of light waves in nonlinear media is examined in an example of LiIO3 and K2S2O6. Peculiarities in the vector interaction are noted in crystals with quadratic and cubic nonlinearities. Experimental results are presented.