Dielectric constants and bond parameters of LiInSe2 and LiGaSe2

The dielectric constants of two lithium ternary chalcogenides, LiInSe2 and LiGaSe2, are obtained to be 8.45 and 8.75, respectively, by capacitance measurements at room temperature. The temperature dependence of dielectric constants of both crystals show linear increase with temperature over the range 77–300 K. The temperature coefficients for LiInSe2 and LiGaSe2 are 2.90×10−4 and 3.80×10−4 K−1, respectively. The bond parameters of LiInSe2 and LiGaSe2 are obtained using the Phillips-Vechten’s and Levine’s dielectric model. The bond characteristics are discussed within the concepts of ionicity and transverse effective charge.