Theoretical Modeling of Elastic, Thermal and Ultrasonic Properties of B1-Dysprosium Monopnictides

Abstract

Nonlinear elastic and thermoacoustical investigation of heavy rare earth pnictides DyPn (Pn=P, As, Sb, Bi) has been carried out at different temperature in different directions. The second and third order, elastic constants for B1 structured DyPn have been obtained in temperature interval 0-300K applying Born-Mayer potential model. The Cauchy and Born stability criteria predict that DyPn are elastically stable. The bulk and shear modulus are decreasing with atomic number which is highest for DyP and lowest for DyBi. The shear modulus to bulk modulus ratio are less than 0.57 which illustrates that chosen DyPn are brittle in temperature span 0-300K. The ultrasonic characteristics of DyPn have been tudied by calculating ultrasonic velocities, thermal conductivity, relaxation time and Grüneisen parameter. The Debye characteristic temperature and thermal conductivity are highest for DyP at 100K along <111> direction for best suited thermal performance. The results of thermal relaxation time show that chosen DyPn are semimetallic in nature. The nonlinear Gruneisen parameter increases as DyBi>DySb>DyAs>DyP. The results in present study are calculated precisely and compared with previous structured values.