Novel spectral properties for La_0.7Ca_0.3CrO₃ ceramics by Mo⁶⁺ doping

The effects of Mo⁶⁺ doping on La_0.7Ca_0.3CrO₃ oxide ceramics synthesized using a solid state reaction method were systematically investigated by thermogravimetric and differential thermal analysis, X-ray diffraction, 3D laser microscopy, UV–Vis spectrophotometry, and infrared diffused reflection measurement. Through these experiments, it was found that the structure, morphology, and spectral properties of the ceramic powders depend on the concentration of Mo⁶⁺ ions. Identification and quantification of crystalline phases using Rietveld refinement revealed the presence of Mo-doped calcium lanthanum chromites and calcium molybdate (CaMoO₄) in doped oxides with ≤0.5 at% Mo, whereas LaCrO₃, CaMoO₄ and La₂Mo₂O₉ were formed at higher concentrations. The mean surface roughness of all the samples was around 0.2 μm, and therefore had little influence on the solar absorptance and infrared emissivity. Calculated values obtained by integrating the spectra identified a low near infrared reflectivity (0.47) with 81 % solar absorptance, indicating the possibility of selectively controlling the spectral properties at a specific wavelength to create functional ceramics with variable near infrared reflectivity for use in solar applications.