SPECIFIC HEAT OF TBXY1-XSB MIXED CRYSTALS

The specific heat of TbxY1-xSb mixed crystals (x=0, 0.103, 0.383, 0.428, 0.467, 0.635, 0.928 and 1.0) has been measured between 1.6 and 20°K using an adiabatic calorimeter. The crystal field potential is described well taking into account only 4th order terms, and the overall splitting of the ground multiplet7F6 of the Tb3+ ion has been found to be 115°K independent of the concentration x. For x>0.46 the specific heat curves exhibit a behaviour typical for a second order phase transition. For lower concentrations a normal Schottky anomaly is found and no evidence for magnetic order was detected. The experimental results which are in agreement with magnetic measurements are compared with molecular field calculations including crystal field and exchange interaction. © 1969 Springer-Verlag.