The Structure and Physical Properties of MnWO 4 Ceramics Replaced by Li + Ions

The impacts of Li + replacement for Mn 2+ on the structure, vacancy defects, and magnetic and dielectric characteristics of Mn 1- x Li x WO 4 ( x = 0.00–0.20) ceramics synthesized by solid-state reaction were investigated. The analysis of XRD and Raman results revealed that Mn 1- x Li x WO 4 samples had single-phase monoclinic structure, and Li + ions had partially replaced Mn 2+ ions and induced lattice deformation and substitutional disorder in Mn 1- x Li x WO 4 . Positron annihilation lifetime spectroscopy indicated that Li + replacement resulted in the reduction of vacancy size and the increase of vacancy concentration. The dielectric properties measurements showed that Li + replacement significantly enhanced the dielectric constant of the Mn 1- x Li x WO 4 samples. It could be observed from the magnetic properties measurements that Li + replacement suppressed the AF1 phase, extended the existing temperature range of AF2 phase, and weaken the magnetization of Mn 1- x Li x WO 4 system. The evolution of magnetic properties was related to vacancy defects, lattice distortion, chemical disorder, and magnetic dilution effect caused by Li + replacement.