The structure, vacancy characteristics, and magnetic and dielectric properties of GdMn1-xWxO3 ceramics

The effects of W 6+ ion substitution at the Mn site on the structure, vacancy characteristics, and magnetic and dielectric properties of GdMnO 3 ceramics synthesized using the solid-state method were investigated. Structural measurements indicate that all GdMn 1- x W x O 3 ceramics exhibit a single-phase structure, and that the introduction of W 6+ ions induces structural distortion. W 6+ substitution changes the valence states of Mn and the oxygen vacancy concentration in GdMn 1- x W x O 3 . Experimental results of positron annihilation indicate that the concentration of cation vacancies increases with increasing W 6+ concentration. The evolution of temperature- and magnetic field-dependent magnetization curves indicates that appropriate W 6+ substitution could evidently improve the magnetization of GdMn 1- x W x O 3 . Dielectric measurements reveal that the W 6+ -substituted samples exhibit giant dielectric characteristics over a broad frequency range. It was found that the magnetization of GdMn 1- x W x O 3 has a close relationship with vacancy concentration, structural distortion, and the dilution effect. Further, the giant dielectric constant behavior of GdMn 1- x W x O 3 ceramics is related to the mixed-valent structure of Mn and the resistivity of grain and grain boundary.