The role of B-site substitution on the structural and dielectric properties of samarium orthoferrite polycrystals

Polycrystalline samples of SmFeO 3 , SmFe 0.5 Co 0.5 O 3, and SmFe 0.5 Cr 0.5 O 3 were prepared by the conventional solid state reaction method. Powder x-ray diffraction pattern confirmed the formation of orthorhombic structure without any impurity phase. Dielectric and impedance properties of the sintered samples were studied as a function of temperature and frequency ranging from 300 K to 550 K and 100 Hz to 50 MHz respectively. The dielectric studies showed interesting properties like dielectric anomaly around spin reorientation temperature suggesting that the magnetic and electric order parameter may be coupled. The behavior of AC conductivity with temperature was explained by hopping mechanisms and the activation energy was found decreased for the doped samples. Nyquist and electric modulus spectra revealed the grain and grain boundary contributions of the sintered samples. The experimental results suggest that the spin reorientation can be tuned in the samarium orthoferrites by changing the B-site ion.