Effects of A-site cationic radius and cationic disorder on the electromagnetic properties of La0.7Ca0.3MnO3 ceramic with added Sr, Pb, and Ba. Issue 5 (1st April 2018)

• Record Type: Journal Article
• Authors: Li, Yule; Zhang, Hui; Chen, Qingming; Li, Di; Li, Zhiyu; Zhang, Yalin
• Is Part Of: Ceramics international. Volume 44:Issue 5(2018)
• Page Start: 5378
• Page End: 5384
• Publication Date: 2018-04-01
• Subjects: La0.7Ca0.25X0.05MnO3 (X = Sr, Pb, Ba) -- Electromagnetic properties -- Temperature coefficient of resistance -- Sol–gel method; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2017.12.165
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: A series of polycrystalline ceramic samples of La0.7 Ca0.25 X0.05 MnO3 (X = Sr, Pb, and Ba) were prepared using sol-gel method with methanol as the solvent. Resistivity-temperature curves show sharp metal-insulator transitions; furthermore, magnetization-temperature curves reveal a transition from ferromagnetism to paramagnetism. After doping with Sr, Pb, and Ba, both average ionic radius of A site and tolerance factor increase. Double-exchange also increases, which supports the metallicity of polycrystalline ceramic. However, larger lattice distortion is also introduced via substitution of larger ions at A site, and this tends to localize carriers. There is competing relationship between tolerance factor enhancement and lattice distortion; in combination, they determine electronic and magnetic properties of polycrystalline ceramics. As a result, after doping with Sr, Pb, and Ba, resistance temperature coefficient decreases, and metal-insulator transition temperature ( T IM ) increases. Meanwhile, ferromagnetic-paramagnetic transition temperature shows the same tendency as T IM .