Effect Of Multielement Doping On LaAlO₃ Infrared Radiation Properties

At present,domestic thermal furnace thermal efficiency is low（about 30%）,while light rare earth（typically La）overcapacity.Lanthanum aluminate is a potential high temperature and high emissivity material with high melting point,good thermal stability and good lattice matching.Therefore,La_0.67A_0.33Al O_3-δ（A=Bi/Ca/Sr,LBA,LCA,LSA）,La Al_0.67B_0.33O_3-δ（B=Co/Mn/Ni,LAC,LAM,LAN）and La_0.67A_0.33Al_0.67B_0.33O_3-δ（A=Ca/Sr,B=Mn/Ni,LCAM,LCAN,LSAM,LSAN）were prepared based on LaAlO₃.The infrared radiation properties of the material were studied by XRD（X-ray diffraction）,SEM（scanning electron microscopy）,XPS（X-ray photoelectron spectroscopy）and other experiments to characterize the hand band.At the same time,the band,density of states,optical properties of the material were simulated by CATEP,and compared with the experimental results.The main conclusions are as follows:A-site single doping:the lattice distortion(4.1×10^-4)and oxygen vacancy（32.25%）of LSA are the largest,the grain size（36.68 nm）and the band gap（3.87 e V）are the smallest,followed by LCA,LBA again,and LA(3.65×10^-4,28.91%,44.44 nm,5.18 e V);The lattice defect formation energy（1.92 e V）and free carrier concentration(1.465×10¹⁸cm^-3)of LSA are the largest,the band gap（3.218 e V）,dielectric function peak（6.70 e V）and absorption peak（8.50 e V）are the smallest,followed by LCA,LBA again,and finally LA(0 e V,2.95×10¹⁷cm^-3,3.445 e V,7.48 e V,9.09 e V).The oxygen vacancy concentration and lattice distortion increased slightly,so the emissivity of the material increase slightly,from 0.1661 of LA to 0.3882 of LSA.B-site single doping:the lattice distortion(9.68×10^-4)and oxygen vacancy（42.84%）of LAN are the largest,grain size（21.71 nm）,band gap（1.78 e V）are the smallest,followed by LAM,LAC,LA;The lattice defect formation energy（7.49 e V）and free carrier concentration(3.838×10¹⁸cm^-3)of LSA are the largest,the band gap（1.184 e V）,dielectric function peak（6.61 e V）and absorption peak（7.84 e V）are the smallest,followed by LAM,LAC,LA.The oxygen vacancy and lattice distortion increase greatly,and at the same time,the impurity level Ni/Mn/Co3d and the small polaron Co²⁺（?）Co³⁺/Mn²⁺（?）Mn³⁺/Ni²⁺（?）Ni³⁺are formation.Therefore,the emissivity of the material increase slightly,from 0.1661 of LA to 0.8531 of LAN.A-B double doping:LSAN has the largestthe lattice distortion(1.46×10^-3)and oxygen vacancy（62.53%）,the smallest grain size（17.66 nm）and band gap（1.39 e V）,followed by LCAN,LSAM,LCAM,LA;LSAN has the largest lattice defect formation energy（9.25 e V）and free carrier concentration(5.811×10¹⁸cm^-3),and smallest band gap（0.113 e V）,dielectric function peak（6.58 e V）and absorption peak（7.12 e V）,followed by LCAN,LSAM,LCAM,LA.The oxygen vacancy and lattice distortion are further increased,and there are still impurity levels Ni/Mn/Co3d and small polaron Mn²⁺（?）Mn³⁺/Ni²⁺（?）Ni³⁺is generated,so the emissivity of the material is further improved,from 0.1661 of LA to 0.9571 of LSAN...