Phonon density of states and heat capacity of CdIn₂S₄

Abstract

In addition t o elementary semiconductors, binary and ternary semiconducting compounds have found ever increasing technological application i n recent years. In this respect diamond-like semiconductors represented by III VI C 4 -type compounds attract close attention of investigators. CdI%S4 whose thermal properties are understood quite imperfectly is a representative of these compounds.This report deals with a study involving measurements of the heat capacity (Cp) of CdInZS4 in the temperature range from 5 to 30 K in a KU-300-type adiabatic calorimeter with an automatic temperature control /l/, as well as i t s thermal expansion ( O L ) and isothermal compressibility ( % ) , i n the tempera t u r e r h g e from 5 to 350 K in a quartz dilatometer described earlier /2/. The C (T) data above of the Cd%S4 phonon spectrum was performed within the framework of a force -constant model. K were taken from another study /3/. A calculation PCdI?S4 specimens were obtained by the double-temperature synthesis meth-The lattice parameter calculated from a Debye powder pattern has proved od.t o be a = 10.83 %, which is in satisfactory agreement with the data of /4/.Measurements of heat capacity at constant pressure, as well a s those of thermal expansion and isothermal compressibility allowed u s to determine the heat capacity a t constant volume and to compare it with the theoretically calculated dependence CV(T).The phonon density of states g( o), from which the theoretical dependence , CV(T) was found, had been calculated within the framework of a force-constant model /5 t o 7/ with four parameters fitted to the experiment. The cqlculation had been performed for an ideal spinel structure with the following parameters: 1 ) Narimanova 33, 3701 43 Baku, USSR.