Abstract: 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 colorperformance, nanoscaled spinel solid solution CoCr_{2- x}Al _xO₄ ( 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 colorspectrometer 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 CoCr_{2- x}Al _xO₄with 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 ofoctahedron group and the complex vibration of octahedron and tetrahedron group. Absorptionbands at 570, 610 and 660 nm inthe visible region of UV-Vis curve are assigned to the ⁴A₂(F)→⁴T₁(P)of Co²⁺ and ⁴A_2g→⁴T_2g ofCr³⁺. Color spectrometer characterization results indicate that the sample exhibits best color performance with x=0.2,showing a bright bluish green color.

Key words: spinel, CoCr_{2- x}Al _xO₄, low-temperaturecombustion synthesis, spectroscopy, color parameters