Distortion of ionic crystals by vacancies

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Expressions are obtained for the energ-of alkali halide crystals with two kinds of simple complexes of point defects -divalent impurity with vacancy and bivacancy -using the lattice static method. The heat of solution of Mg2+, Ca2+, Sr2+, and Ba2+ in NaCl, KCl, and KBr is calculated. Numerical calculations show that in some cases the nearest-neighbour complex is less stable than the next-nearest-neighbour complex. The formation energy of a bivacancy is calculated in the same crystals. The results are consistent with those obtained experimentally. It is shown that in the latter case the configuration of the nearest-neighbour complex is the most stable one.

“…The energy is calculated using the Ewald method, as suggested in [7]. The adiabatic part of the defect energy can be represented as follows: e2…”

Section: Divalent Impurity With Vacancymentioning

confidence: 99%

Section: Divalent Impurity With Vacancymentioning

confidence: 99%

Section: Divalent Impurity With Vacancymentioning

confidence: 99%

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A Theoretical Study of Simple Complexes of Point Defects in Alkali Halides by the Lattice Static Method

Augst

Vladislavskii

1984

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Self‐Interstitials in Normal Metals

Augst¹

1981

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General expressions describing the formation energy of interstitials of different configurations in simple metals are obtained. The electronic contribution is considered within the framework of pseudopotentials theory and is based on the linear response approximation. To obtain the lattice relaxation energy two terms of the displacement expansion iteration series are calculated. Numerical calculations for aluminium show that the minimum energy corresponds to a 100 dumb-bell, with the distance of each ion from the vacancy being 0.52a/2. For interstitials of other configurations the disturbance of the lattice is so strong that the iteration series for the relaxation energy is divergent.nOJIyseHb1 o 6~~e BMpa?HeHHR AJIJI 3HeprHEl 06pa30BaHHH MemAOy3JIHfi pa3JIM9HbIX HOH@llrypaUITfi B HOpMaJIbHbIX MeTaJIJIaX. Bman 3JIeKTPOHOB PaCCMaTpHBaeTCH B paMKaX TeOpllH IIceBAOIIOTeHUHaJIOB B n p~6 n n r n e~~r n JIHHefiHOrO OTHJIEIKB. &lIR HaXOWneHHR meHllHM. YHCJIeHHbIe PaCueTbI AJrR aJIIOMAHHEI IlOKa3aJlE1, 9TO MUHUMaJIbHaFI 3HeprHH COOTBeTCTBYeT raHTeJIEl 100 C PaCCTOJIHHeM OT BaIiaHCHH Ha?l

Calculation of the Heat of Solution in Alkali Halide Crystals by the Lattice Static Method

Augst

Bakhshetsyan

1981

All studies on the calculation of the heat of solution in alkali halide c r y s t a l s are based on the semi-continuum approximation /l/. In spite of the fact that in some works /2, 3/. the region in which the lattice relaxation is calculated accurately is great, the lattice static method /4/ has the advantage, that all calculations are done by "first principles". It consists in that the interionic interaction potentials have to b e given only.tice static method developed in /5/ applied t o a vacancy in ionic crystals was used. In the c a s e the substitutional ion has the s a m e charge as the host matrix ion, the electrostatic energy of the crystal can be written using the Ewald method in the form of the energy of the ideal crystal not fixing, however, the ions on i t s sites. The non-Coulomb part of the energy can be represented as follows:In the present work in o r d e r to calculate the substitutional impurity the lat-