Influence of A-site cation disorder on structural and magnetocaloric properties of Nd0.7-xLaxSr0.3MnO3 （x=0.0, 0.1, 0.2 ＆ 0.3）

• Published in: 中国稀土学报：英文版 2015, Vol.33 (10), p.1072-1080
• Main Author: Sudharshan Vadnala Prem Pal Saket Asthana
• Format: Article
• Language: English
• Subjects: 固相反应法; 斜方晶系; 磁制冷技术; 磁熵变; 离子半径; 紊乱; 结构性能; 转变温度
• ISSN: 1002-0721; 2509-4963

In the present research, the influence of A-site ionic size disorder on structural, magnetic and magnetocaloric properties of Ndo.7_xtaxSr0.3MnO3 （for x=0.0, 0.1, 0.2 ＆ 0.3） compounds were investigated. These compounds were synthesized by solid state reaction route and crystallized in orthorhombic structure with Pnma space group. An average ionic radius 〈rA〉 increased with La-substitution which influenced the physical properties such as the magnetic entropy varying from 4.78 J/kg.K （for x-=0.0） to 3.55 J/kg.K （for x=0.3） and the maximum magnetization at 5 K changing from 3.92 μB （for x=0.0） to 3.59 μB （for x=0.3）. The change in maximum magnetic entropy decreased with increase of A-site average ionic radius. The decrease in magnetic entropy indicated the suppression of lattice disorder that influenced the spin-lattice coupling. The ferromagnetic transition temperature shifted toward room temperature with La substitution. As 〈rA〉 increased, the phase transition changed from first order （for x-=0.0） to second order （for x≥ 0.1） and the refrigeration capacity increased to a significant level. The modest change in magnetic entropy over a wide range of transition temperature might be useful for future active magnetic refrigeration technology.