High-temperature synthesis and electronic bonding analysis of Ca-doped LaMnO_(3) rare-earth manganites  

作　　者：Natarajan Thenmozhi Ramachandran Saravanan 

机构地区：[1]Post Graduate and Research Department of Physics,Nadar Mahajana Sangam S.Vellaichamy Nadar College,Nagamalai,Madurai,Tamil Nadu,625019,India [2]Research Centre and Post Graduate Department of Physics,The Madura College,Madurai,Tamil Nadu,625011,India

出　　处：《Rare Metals》2022年第11期3932-3942,共11页稀有金属（英文版）

摘　　要：Doped lanthanum manganites La_(1-x)Ca_(x)MnO_(3) with five different concentrations of Ca(x=0.1,0.2,0.3,0.4 and 0.5) were synthesized by high-temperature solidstate reaction method and characterized.The prepared samples were experimentally analyzed by X-ray diffraction(XRD),ultraviolet-visible spectroscopy(UV-Vis),scanning electron microscopy/energy dispersive spectroscopy(SEM/EDS) and vibrating sample magnetometer(VSM)measurements.Orthorhombic structure is confirmed for this compound from powder X-ray diffraction data.The XRD data confirm the shrinkage in the unit cell of synthesized samples for increasing calcium concentration.The UV-Visible analysis for the estimation of optical band gap(E_(g)) reveals that the band gap decreases with the incorporation of Ca.The synthesized samples were investigated for charge density distribution using maximum entropy method,utilizing the XRD data sets.From the charge density analysis,it is found that the bond lengths for La-O and Mn-O bonds decrease with the addition of Ca.The ionic nature between La and O atoms and covalent nature between Mn and O atoms are enhanced for 40% of calcium-doping.For 50% of Ca-doped sample,ionic nature between La and O atoms and covalent nature between Mn and O atoms decrease.All the prepared samples exhibit ferromagnetism at 20 K and paramagnetism at 300 K.

关 键 词：MANGANITES Mixed valency MAGNETOCALORIC Magnetoresistive SOFC 

分 类 号：TB34[一般工业技术—材料科学与工程]