Thermal Expansion and Magnetostriction in Pr5Ni2Si3 Single crystal

Pr$_{5}$Ni$_{2}$Si$_{3}$ is the second member of the series, R$_{(n+2)(n+1)}$Ni$_{n(n-1)+2}$Si$_{n(n+1)}$, which consists of three compounds with n= 2,3 and 4 with similar hexagonal crystal structures and exhibiting uniaxial magnetic anisotropy with an easy c axis. In this study, thermal expansion and magnetostriction of Pr$_{5}$Ni$_{2}$Si$_{3}$ single crystals were investigated parallel and perpendicular to the easy axis over the temperature range of 5 to 300 K under applied magnetic field up to 9 T. The magnetic contribution to the thermal expansion was determined by approximating the phonon contributions to thermal expansion using the Debye-Gruneisen model. The results reflect two different magnetic phase transformations upon cooling, one corresponding to the Curie temperature (41 K) and the other exhibiting characteristics of a spin reorientation. Ames Lab. is operated for the US Department of Energy by Iowa State University under contract number W-7405-ENG-82.