La_(0.8)Ca_(0.2)Fe_(0.5)X_(0.5)O_3型氧化物的制备及其近红外发射率研究

Study on the preparation and near infrared emissivity of La_(0.8)Ca_(0.2)Fe_(0.5)X_(0.5)O_3 type oxide

利用固相反应法在1 300℃下合成La_(0.8)Ca_(0.2)Fe_(0.5)X_(0.5)O_3(X=Fe、Cu、Cr、Mn)氧化物,并对它们在近红外波段的发射率进行了研究和比较,通过XRD、XPS、FT-IR等对样品进行分析和表征。研究结果表明,合成的La_(0.8)Ca_(0.2)Fe_(0.5)X_(0.5)O_3型氧化物样品为单相正交晶系。掺杂后的试样较LaFeO_3在200~2 500nm近红外波段的发射率均提高60%以上,其中Ca-Cr>Ca-Cu>Ca>Ca-Mn>不掺,可能是掺杂引入Fe^(4+)杂质能级增强了自由载流子浓度及其带隙之间的跃迁,不同元素掺杂引起Fe^(3+)Fe^(4+)的跃迁程度与氧空位的浓度存在差异,导致不同掺杂元素发射率不同。La_(0.8)Ca_(0.2)Fe_(0.5)X_(0.5)O_3型氧化物材料均具有优异的近红外辐射性能,能够在高温热工节能领域发挥作用。

La_（0.8）Ca_（0.2）Fe_（0.5）X_（0.5）O_3（X=Fe,Cu,Cr,Mn）oxides were synthesized by solid phase reaction at 1 300℃.They were studied and compared in near infrared emissivity and characterized by XRD,XPS and FT-IR.The results show that the synthesized La_（0.8）Ca_（0.2）Fe_（0.5）X_（0.5）O_3 type oxide sample is single phase.The emissivity of LaFeO_3 in the near infrared band of 200-2 500 nm was increased by more than 60%after dopingand the Ca-CrCa-CuCaCa-MnCa-Cr was not mixed.The doped Fe^（4＋） impurity level enhanced free carrier concentration and transition band gap.The different doping concentration of Fe3＋caused different transition Fe^（4＋） and oxygen vacancies,resulting in different emission rates of different doping elements.La_（0.8）Ca_（0.2）Fe_（0.5）X_（0.5）O_3 type oxide materials have excellent near infrared radiation properties,which can play a role in the field of high temperature thermal energy conservation.