Study of the Effects of A‐Site La‐Substition on the Electrical and Magnetic Properties of Dy0.5Sr0.5MnO3 Ceramics

Abstract

The Dy0.5−xLaxSr0.5MnO3 (0 ≤ x ≤ 0.4) manganite compounds have been synthesized by solid state reaction, and the effect of nonmagnetic La ion doping on the crystal structure, electrical and magnetic properties are systematically investigated. It is found that with successive substitution of La element, A‐site cationic arrangement transforms from disorder (random, x ≤ 0.25) to order structure (x > 0.25), and the crystal structure undergoes a transition from cubic to orthogonal distorted perovskite structure. When 0 ≤ x < 0.25, the compounds show a similar semiconducting behavior and magnetic property with a low‐temperature spin‐glass state. When x = 0.25, however, long‐range ferromagnetic (FM) order begins to form and coexists with anti‐ferromagnetic (AFM) phase in the compound. When x further increases, FM interactions strengthen and become predominant in the magnetic properties of the compound. On the other hand, in contrast to the semiconducting behavior of the compounds with x ≤ 0.25, when x > 0.25, the resistivity decreases quickly in the corresponding temperature range. It is suggested that not only the A‐site cationic disorder turning, closely related to the cation radius distribution (mismatch), σ2, controlled by A‐site cation radius 〈rA〉, but the substitution of nonmagnetic La ions, or A‐site magnetic change, is an effective way to adjust the crystal structure and the related magnetic and electrical properties of the perovskite manganite oxides for the applications.