The effect of manganese doping on the structural, magnetic and dielectric properties of breathing pyrochlore LiInCr4-xMnxO8

Abstract

In the present paper, polycrystalline samples of LiInCr4-xMnxO8 varying from 0.0 to 0.5 were synthesized by the solid state method. In order to explore the effect of substitution Cr by Mn in LiInCr4O8, the structural, magnetic and dielectric properties are studied. The result of XRD patterns show that there is a nonmonotonic expansion in the lattice parameter, which may be due to ions disorder or/and partial exchange between A- and B-atoms. The SEM micrographs show that the Mn substituted samples are smaller in the average crystallite size and more agglomerated than the parent material. Magnetization data show the nonmonotonic variation of the effective magnetic moment and Curie-Weiss temperature, the suppressed long-range antiferromagnetic (AFM) order and spin gap, and occurrence of a spin glasslike state. Although the breathing pyrochlore lattice is robust against doping, only 5% doping concentration (x = 0.2) makes the spin gap vanish absolutely. The increased Bf makes the pyrochlore lattice more uniform, leading to the disappearance of the spin gap. The dielectric data show that Mn doping increases the dielectric constant and decreases dielectric loss at room temperature, thus these compounds should be satisfactory to the possible application in microelectronics. The result of heat capacity also verifies glass-type insulator state.