Influence of the structure of CrPO4 on the formation of CrVxP1-xO4 solid solutions and their colour

Abstract

CrVxP1−xO4 (0 ≤ x ≤ 1) compositions were synthesized via the chemical co-precipitation method. At 600 °C, the detected crystalline phase is monoclinic CrVO4 when x ≥ 0.7. At 800 °C, two isostructural phases with orthorhombic symmetry are detected. At this temperature, β-CrPO4 is present when x ≤ 0.7 and orthorhombic CrVO4 when 0.1 ≤ x ≤ 0.9. The two orthorhombic phases, β-CrPO4 and CrVO4, are stable at 800 and 1000 °C. At 1200 °C, the major crystalline phase is the α-CrPO4 polymorph when x ≤ 0.3. This phase is not present when x ≥ 0.7. The unit cell increase confirms the formation of solid solutions with the α-CrPO4 and β-CrPO4 structure. The CrVxP1−xO4 solid solutions (x < 0.3) with the α-CrPO4 structure can be used as a green ceramic pigment because of their thermal and chemical stability.