Inter-relationship between optical dielectric constant and interatomic separation of mixed crystals in ionic and covalent binary compound families Original Research Article

An ion dependent dielectric model is developed for mixed binary crystals. The interatomic separation (R) and optical dielectric constant (ε∞) of the mixed crystals are computed from the measured values of R and ε∞ of pure crystals. An empirical relation between ε∞ and R is therefore found for mixed crystals by using the computed values. It is found that the dielectric behaviour of ionic mixed crystals is cation dependent while that of covalent mixed crystals is anion dependent. The prescribed theory can therefore be used to form different mixed crystals with particular values of ε∞ required in any specific opto-electronic devices.