Structural and electronic properties of Sr1-xCaxTi0.5Mn0.5 O3

Abstract

The series of Sr 1− x Ca x Ti 1/2 Mn 1/2 O 3 perovskites has been prepared using solid state methods and their structures determined using combination of synchrotron X-ray and powder neutron diffraction. At room temperature the crystal structure evolves with increasing Ca content from P m 3¯ m→ tetragonal I4/mcm→ orthorhombic Pbnm, as a consequence of the sequential introduction of cooperative tilting of the (Ti/Mn) O 6 octahedra. X-ray absorption measurements show the Mn is tetravalent in all oxides. Magnetic susceptibility measurements demonstrate all the oxides to be paramagnetic at room temperature, with a transition to a spin glass arrangement occurring at low temperatures. Electrical measurements prove that all the members are semiconductors and their activation energy increase with Ca doping amount.