Influence of temperature on the structural and color properties of nickel molybdates

In this work, nickel molybdates were synthesized by co-precipitation method, at 70 °C, and were thermally treated at temperatures ranging from 300 to 1000 °C. Firstly, the hydrated precursor (NiMoO4.0.65H2O) was obtained, followed by calcination at 300–600 °C to produce a mixture of β- and α-NiMoO4 phases. The pure α phase could only be obtained above 700 °C. The relationships among the crystal structure, colorimetric parameters, and...