Preparation, structure, and electrical conductivity of La(Ga,Mn)O 3 ceramics

(La0.9□0.1)(Ga1-xMnx)O y (□ = vacancy; x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) perovskite solid solutions are prepared by solid-state reactions and characterized by x-ray diffraction, electron microscopy, and dielectric spectroscopy. The solid solutions have a rhombohedral structure over the entire composition range. Mn substitution leads to a transition from ionic hopping conduction, with a linear variation of log (σT) with 1/T, to ionic-electronic conduction. The unit-cell volume and conductivity of the solid solutions are shown to correlate with their tolerance factor.