STRUCTURE, MAGNETIC-SUSCEPTIBILITY AND HEAT-CAPACITY OF SCMNO3

Structure refinement of the room temperature X-ray powder diffraction data of ScMnO3 was carried out by Rietveld technique, based on the mos t probable space group P6(3)cm. The manganese and scandium atoms are s urrounded by five and seven oxygen atoms respectively. Three manganese atoms make three kinds of triangles (two regular and an isosceles). A weak ferromagnetic behaviour with small hysteresis was observed below 130 K on the magnetization curve and ScMnO3 becomes completely parama gnetic above it. The heat capacity of ScMnO3 was measured from 77 to 8 00 K by two types of calorimeters (a.c. calorimeter and differential s canning calorimeter). At 129 K a lambda-type anomaly was seen in the h eat capacity curve which corresponds to the magnetic transition. The e nthalpy change and entropy change that accompanied the magnetic transi tion were 178 J mol(-1) and 1.40 J mol(-1) K-1 respectively. The basel ine of the heat capacity from 150 to 250 K yields a Debye temperature of 615 K.