Preparation and Spectroscopy Analysis of Spinel CoCr_(2-x)Al_xO_4 by Low-temperature Combustion Synthesis

As a member of complex metal oxides,spinel CoCr2O4 has wide application in ceramic pigment,catalysis and magnetic materials.In order to reduce the Cr content and modify the color performance,nanoscaled spinel solid solution CoCr2-xAlxO4(x=0,0.05,0.1,0.2,0.3 and 0.5) was synthesized by low-temperature combustion synthesis(LCS) method using citric acid(reductant) and metal nitrates(oxidants) as starting materials.XRD,TEM,FT-IR,UV-Vis spectrometer and color spectrometer were employed to characterize the structure,morphology,infrared,ultraviolet-visible curve and the color parameters of the as-prepared sample,respectively.Results show that single-phased and uniform CoCr2-xAlxO4 with about 15 30 nm in size can be prepared by LCS at 800 ℃.Absorption bands at about 520 cm 1,630 cm 1 and 410 450 cm 1 in IR curve are corresponding to the vibration of octahedron group and the complex vibration of octahedron and tetrahedron group.Absorption bands at 570,610 and 660 nm in the visible region of UV-Vis curve are assigned to the 4A2(F)→4T1(P) of Co2+ and 4A2g→4T2g of Cr3+.Color spectrometer characterization results indicate that the sample exhibits best color performance with x=0.2,showing a bright bluish green color.