The effects of SiO₂ content on the phase and microstructures of high emissivity ceramic material, Ca²⁺-Cr³⁺ doped LaAlO₃ (LCCA) was investigated. The addition of SiO₂ led to the formation of silicate Ca₂La₈(SiO₄)₆, Ca₂SiO₄ and Al-Si-Ca-La-O glass phase in the LCCA pellets. With the increase of SiO₂, doped LaAlO₃ phase decomposed gradually and nearly disappeared at 20 wt% SiO₂. Besides, the infrared radiation property attenuated with the content of SiO₂. The emissivity was decreased from 0.93 in the absence of SiO₂ to 0.88 in the presence of 20 wt% SiO₂. It indicates that SiO₂ content should be carefully controlled when SiO₂ or SiO₂-containing sol is used a high temperature binder. 

Materials Letters 

Volume 171, 15 May 2016, Pages 55–58

SEM images of La0.8Ca0.2Cr0.1Al0.9O3 pellets incorporated with (a) 0 wt%, (b) 5 wt%, (c) 10 wt%, and (d) 20 wt%, and corresponding EDS spectra (e) and (f) detected on area A and B shown in (b).