Summary
The Born-Mayer model of ionic solids is used to calculate the binding energy of a positive-ion vacancy and a negative-ion vacancy at the distance of nearest neighbours in NaCl and KC1 crystals: the results are 0.6 eV and 0.7 eV respectively. This leads one to expect in NaCl an equilibrium concentration of vacancy pairs ranging from 10% to 20% of the equilibrium concentration of Schottky defects between 500 °C and 700 °C. The available experimental data are compatible with the existence in the alkali halide crystals of an equilibrium concentration of vacancy pairs of this order of magnitude in the intrinsic temperature reeion.
Riassunto
Il modello di Born e Mayer dei solidi ionici è utilizzato per calcolare l’energia di legame di un posto vacante da ione positivo e di un posto vacante da ione negativo alla loro minima distanza reticolare in cristalli di NaCl e di KC1: i risultati sono rispettivamente 0.6 eV e 0.7 eV. Per il NaCl, questo porta ad una concentrazione di equilibrio di coppie di posti vacanti variabile fra il 10% ed il 20% della concentrazione di equilibrio di difetti Schottky nell’intervallo fra 500 °C e 700 °C. I risultati sperimentali disponibili sono compatibili con l’esistenza negli alogenuri alcalini di una concentrazione di equilibrio di coppie di posti vacanti di questo ordine di grandezza nella regione intrinseca di temperature.
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The first paper of this series was published inNuovo Cimento,11, 274 (1954).
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Tosi, M.P., Fumi, P.G. The interaction between equilibrium defects in the alkali halides: the «ground state» binding energy of the vacancy pair. Nuovo Cim 7, 95–106 (1958). https://doi.org/10.1007/BF02746885
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DOI: https://doi.org/10.1007/BF02746885