Crystal structure and electrical transport properties of polycrystalline TbMn_1-xFe_xO₃

Polycrystalline TbMn_1-xFe_xO₃ (x=0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) were synthesized by solid sintering method. The Rietveld refinement results based on the X-ray powder diffraction (XRD) data showed that all samples were identified as orthorhombic perovskite structure with space group Pbnm (62). The lattice parameters a and c increased, while the b decreased with increasing of Fe content, indicating the crystal unit cell shrinks in the ab-plane and extends along c-axis with increasing concentration of Fe. Temperature dependent resistance (R-T) was also measured. The transition temperature of TbMn_1-xFe_xO₃ samples increased monotonically with increase of x. The activation energy of TbMn_1-xFe_xO₃ decreased with increasing Fe content (x≤0.5) and increased with increasing Fe content when x>0.5, meaning that the TbMn_0.5Fe_0.5O₃ has the lowest activation energy. These results implied that the transition temperature and conductivity could be controlled by impuring different elements, especially to obtained better performance as for the semiconductor materials working at broad temperature.