Effect of A-site rare-earth ions on structure and magnetic properties of novel (Ln0.2Gd0.2La0.2Nd0.2Sm0.2)MnO3 (Ln = Eu, Ho, Yb) high-entropy perovskite ceramics

Abstract

Single-phase high-entropy perovskite ceramics (Ln0.2Gd0.2La0.2Nd0.2Sm0.2)MnO3 (Ln-GLNSMO HEPCs) have been synthesized using solid-state reactions. The effect of A-site rare-earth ions (Ln = Eu, Ho, Yb) on the structure and magnetic properties was systematically investigated. The results show that all samples are orthorhombic phases (with a space group of Pbnm) and exhibit a strong crystallization trend sintered at 1300 °C for 16 h. All the HEPCs are composed of irregular spherical particles with smooth surfaces and show obvious hysteresis effects at T = 5 K. The changing Mn–O bond distance, Mn–O–Mn bond angle and the increase of Mn4+ ion concentration enhance the double exchange effect of Mn3+-O2--Mn4+, leading to different magnetic interactions. The residual magnetization Mr (coercivity Hc) of the samples is significantly enhanced, which is increasing from 0.13 emu/g (16.34 Oe) to 3.17 emu/g (97.07 Oe) due to the increase of configuration entropy, lattice distortion and the double exchange effect (DE). In addition, there is a strong relationship between the magnetic properties and the average radius of the A-site ions, in which Ho-GLNSMO HEPCs have a high Ms magnetism. This work is a valuable reference for the magnetic regulation of high-entropy ceramics based on rare-earth and entropy-stabilized perovskite types.