An evaluation of the impact of Ca substitution on the structural and magnetic properties of GdMnO3 ceramics

Abstract

To investigate the effects of structural modulation induced by Ca substitution on the magnetic properties of GdMnO3 systems, Gd1-xCaxMnO3 (x = 0.00–0.30) multiferroic ceramic samples were prepared via a solid-state reaction. The XRD, Raman, backscattered electron images results indicated that all of the synthesized compounds formed single-phase structures, without other detectable impurity phases. Ca2+ ions had fully incorporated into the lattice position of the GdMnO3, resulting in structural distortion. XPS results indicated that Mn4+ ions were introduced in all of the samples, while oxygen vacancies were introduced in the x > 0.10 samples. SEM images showed that the microstructure of the prepared samples was dense, and the grain size was approximately a few microns and changed with the amount of Ca substitution. Positron annihilation lifetime spectroscopy revealed that large amounts of cation vacancies were present in the Gd1-xCaxMnO3 ceramics; the vacancies concentration obviously changed as the Ca content increased. Magnetic properties measurements showed that Ca substitution obviously modified the low-temperature magnetic behaviors of the Gd1-xCaxMnO3, and the appropriate substitution amount of Ca improved the magnetic properties due to Mn4+ ions in GdMnO3 system introduced by Ca substitution. The investigations demonstrated that the evolution of magnetic properties was closely associated with the concentration of cation vacancies and Mn4+ ions in the Gd1-xCaxMnO3 samples.