SYNTHESIS, STRUCTURE AND CHARACTERIZATION OF CE1-XAXTIO3 (0.0 LESS-THAN-OR-EQUAL-TO X LESS-THAN-OR-EQUAL-TO 0.8, A = SR, BA)

The investigation of the solid solution Ce1-xAxTiO3 (A = Sr, Ba) was undertaken with the aim to understand the magnetic and electronic properties as a function of alkaline earth doping. The solid solutions Ce1-xAxTiO3 (A = Sr, Ba; 0.0 less-than-or-equal-to x less-than-or-equal-to 0.8) have been prepared by arc melting stoichiometric amounts of CeTiO3 and ATiO3 under argon. Single-phase samples of Ce1-xSrxTiO3 can be made for the entire stoichiometry range. However, there is phase separation in samples of Ce1-xBaxTiO3 for high values of x. The polycrystalline samples have been characterized using microprobe, thermal gravimetric analysis, powder X-ray diffraction, Ce L-edge X-ray absorption fine structure, temperature- and field-dependent magnetization, and dc electrical resistivity. The Ce1-xSrxTiO3 samples crystallize in the orthorhombic space groups Pbnm (x less-than-or-equal-to 0.4) and Ibmm (0.4 < x less-than-or-equal-to 0.8). The Ce1-xBaxTiO3 Samples crystallize in the orthorhombic space groups Pbnm (x less-than-or-equal-to 0.2) and Ibmm (0.2 < x less-than-or-equal-to 0.6). The Ce0.2Ba0.8TiO3 Sample is biphasic containing an orthorhombic phase (Ibmm) and a hexagonal BaTiO3-x phase. Ce XANES (X-ray absorption near-edge structure) data show that in all samples the Ce valence is 3+. The samples Ce1-xSrxTiO3 (x = 0.0, 0.2) exhibit a ferromagnetic component below 135 K due to coupling between Ce and Ti moments. The temperature dependent resistivity measurement on polycrystalline CeTiO3 shows it to be a small gap (0.005 eV) semiconductor. The Ce1-xSrxTiO3 samples are metallic up to x = 0.8 while the Ce1-xBaxTiO3 samples are metallic for x = 0.2, 0.4.