Chandan Gupta*, Kailash and Jitendra Kumar
A theoretical approach to evaluate the temperature variation of second third and fourth order elastic constants (SOECs, TOECs and FOECs) for FCC crystal structure solids is developed on the basis of long range and short range potentials using some basic parameters like nearest-neighbour distance and hardness parameter. This theoretical approach is used to calculate second, third and fourth orders elastic constants (SOEC, TOEC and FOEC) of Lanthanum Selenide single crystals from temperature range 300 K to1000 K. The knowledge of the higher-order elastic constants for a crystal is useful for obtaining the anharmonic properties of the crystals within the limit of the continuum approximation. The Lanthanum Selenide crystal possesses face centered cubic crystal structure. The data of SOECs, TOECs and FOECs are used to obtain the first-order pressure derivatives (FOPDs) of SOECs and TOECs, second-order pressure derivatives (SOPDs) of SOECs and partial contractions. The data of Lanthanum Selenide crystals obtained through different techniques give important and valuable information about the internal structure and inherent properties of materials.
Keywords: Anharmonic Behaviour, Elastic Constants, Lanthanum Compounds.