Theoretical study of intrinsic point deffects inkalkali halide crystals

Murti, Y. V. G. S.; Usha, Venkatesh

doi:10.1016/0378-4363(76)90121-2

Cited by 9 publications

(13 citation statements)

References 19 publications

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“…The above-mentioned studies have been made by using two-body potentials which, generally consist of long-range Coulomb and short-range repulsive and/or van der Waals interactions. Murti and Usha have reported the formation energy and binding energy of the vacancy pair in NaCl and KCl by using the modified polarizable point ion (PPI) model [6] in the framework of Mott and Littleton's approximation [7]. These results are in reasonable agreement with the corresponding experimental results on vacancy pair formation energy (ItVP).…”

Section: Introductionsupporting

confidence: 58%

“…Here we find a very good agreement with the experimental value of the formation energy of a vacancy pair. These energies reported by Murti and Usha [6] are large. Smaller values of the binding energy of a vacancy pair have been reported by several authors [14 to 161.…”

Section: Resultsmentioning

confidence: 77%

“…In Table 1 we give the displacements of the first ten neighbouring atoms of the vacancy pair for NaCl and KCl. Various contributions of the energy terms are given in Table 2 along with those reported by Murti and Usha [6]. It can be seen from this table that TBI contributes significantly to the polarization energy ( E , and E5), although its contribution to the long-range energy is not significant as the value of interatomic separation is different.…”

Section: Resultsmentioning

confidence: 90%

“…1. Distorted lattice configuration due to the vacancy pair in a NaC1-type crystal The above energy expression can also conveniently written as [6] where E , is the energy required to create the vacancy pair. E2,,,R is the change in long-range Coulomb and TBI energies due to the relaxation of region I ions.…”

Section: Methods Of Calculationmentioning

confidence: 99%

“…Thus the model suffers from severe drawbacks in revealing the defect process, polarization mechanism, ete. In addition the PPI model cannot explain the elastic and dielectric properties of ionic solids satisfactorily [6] and hence the description of defect properties from such a model seems to be quite unreliable.…”

Section: Introductionmentioning

confidence: 99%

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Charge transfer effect on formation and binding energies of vancancy pairs in NaCl and KCl

Rao

Sanyal

1991

Physica Status Solidi (b)

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Charge transfer effect on formation and binding energies of a vacancy pair in NaCl and KCl solids is investigated by using a sophisticated model potential, which includes long range many body forces. These forces have a strong influence on the relaxing ions and mechanism of polarization. The formation energy and binding energy calculated from this potential are in good agreement with experiment.Mit einem komplizierten Modellpotential, das weitreichende Vielkorperkrafte einschlieot, wird der LadungstransfereinfluB auf die Bildungs-und Bindungsenergien eines Leerstellenpaars in NaC1-und KCI-Festkorpern untersucht. Diese Krafte haben einen starken EinfluR auf die relaxierenden Ionen und Polarisationsmechanismen. Die Bildungsfnergie-und Bindungsenergieberecl-nungen mit diesem Potential sind mit dem Experiment in guter Ubereinstimmung.

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Section: Introductionsupporting

confidence: 58%

Section: Resultsmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 90%

Section: Methods Of Calculationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Charge transfer effect on formation and binding energies of vancancy pairs in NaCl and KCl

Rao

Sanyal

1991

Physica Status Solidi (b)

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Formation enthalpy of schottky defects in alkali halide crystals and of anti-Frenkel defects in CaF2-type crystals

Bollmann

1980

Phys. Stat. Sol. (a)

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on the occasion of his 75th birthday The formation enthalpy hs of Schottky defects in alkali halide crystals is related to the heat L and temperature T, of fusion: hs == 8 L/NA (NA Avogadro constant) with L = (0.0352 K-l T, -11) kJ/mol. This means that the vacancy mechanism governs the melting process of alkali halides. The formation entropy $5 of Schottky defects is given by BQ = (2 to 3) s , ( 8 , entropy of fusion). The formation enthalpy ~A F of anti-Frenkel defects in MeX2 crystals of fluoritetype (Me metal; X halogen, oxygen) depends on the heat L of fusion, too: ~A F = 1.37 eV +-Die Bildungsenthalpie hs der Schottky-Defekte in Alkalihalogenidkristallen steht in direktem Zusammenhang mit der Schmelzwiirme L und der Schmelztemperatur T,: hs = 8 L / N A (NA Avogadro-Konstante) mit L = (0,0352 K-l T, -11) kJ/mol. Das bedentet, da13 das Schmel-Zen der Alkalihalogenide durch den Leerstellenmechanismus bestimmt wird. Die Bildungsentropie ss der Schottky-Defekte ist ss = (2 bis 3) s , ( 8 , Schmelzentropie). Die Bildungsenthalpie ~A B der Anti-Frenkel-Defekte in MeX,-Kristallen vom Fluorit-Typ (Me Metal1 ; X Halogen, Sauerstoff) ist ebenfalls proportional zu L: ~A F = 1,37 eV + 3,44 L / N A .-+ 3.44 L/NA.

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A theoretical calculation on Schottky defects in AgCl

Banhatti

Murti

Laskar

1991

Physica Status Solidi (b)

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The formation of Schottky defects in crystalline AgCl is investigated using interatomic potentials compatible with the macroscopic dielectric response of the solid with consistent van der Waals interaction coefficients. It is shown that two-body central interactions in a point dipole model can yield satisfactory defect formation energy provided the dielectric polarization of the distorted defect crystal is adequately simulated. The calculated formation energy of the Schottky defect is 2.0eV according to the potential that includes dipole-quadrupole van der Waals forces. The variation of the defect energy with temperature is studied in a quasiharmonic approximation.Die Bildung von Schottkydefekten in kristallinem AgCl wird mit interatomaren Potentialen untersucht, dtk mit der makroskopischen dielektrischen Response des Festkorpers mit konsistenten van der Waals-Wechselwirkungskoeffizienten kompatibel sind. Es wird gezeigt, dal3 zentrale Zwei-Korperwechselwirkungen in einem Punktdipolmodell befriedigende Defektbildungsenergie liefern kann, vorausgesetzt, die dielektrische Polarisation des gestorten Defektkristalls wird adaquat simuliert. Die berechnete Bildungsenergie des Schottkydefekts betragt 2,0 eV entsprechend dem Potential, das Dipol-Quadrupol-van der Waals-Krafte einschlieflt. Die Anderung der Defektenergie mit der Temperatur wird in einer quasiharmonischen Nlherung untersucht.

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Theoretical study of intrinsic point deffects inkalkali halide crystals

Cited by 9 publications

References 19 publications

Charge transfer effect on formation and binding energies of vancancy pairs in NaCl and KCl

Charge transfer effect on formation and binding energies of vancancy pairs in NaCl and KCl

Formation enthalpy of schottky defects in alkali halide crystals and of anti-Frenkel defects in CaF2-type crystals

A theoretical calculation on Schottky defects in AgCl

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