Structural and electromagnetic characteristics of perovskites in La_1–c–xSr_c+xMn_1–xMe⁴⁺_xO₃ systems (Me=Ge, Ti)

¹ Astrakhan State University, 414056 Astrakhan, Russia
² Institute for Metallurgy UB RAS, 620016 Yekaterinburg, Russia

Abstract

Experimental data are shown for the influence of substituting quadrivalent ions on the concentration phase transitions “rhombohedral-orthorhombic structure” and “semiconductor-metal” in ceramic manganites of specifically designed system La³⁺_1–c–xSr²⁺_c+xMn³⁺_1–c–xMn⁴⁺_cMe⁴⁺_xO₃ (c=0.15, 0.17, 0.19; 0.025≤x≤0.125). Regularities in the concentration dependences of unit cell volume, saturation magnetization, Curie point, and resistivity were established. Ge-substituted manganites had essentially higher values of magnetization and Curie temperature than analogous compositions with Ti. The approach to the interpretation of experimental results is discussed in terms of electron configurations and ionic radii of substituents taking into account oxygen nonstoichiometry and cation vacancies.