High substitution of Fe3+ for Zr4+ in ZrV1.6P0.4O7 with small amount of FeV0.8P0.2O4 for low thermal expansion

Abstract Fe 3+ -doped ZrV 1.6 P 0.4 O 7 with Fe:Zr molar ratios of 1:9, 2:8, 3:7 and 4:6 was synthesized to reduce phase transition and obtain low thermal expansion. It is shown that the phase transition temperature of Fe-doped ZrV 1.6 P 0.4 O 7 is reduced obviously with increasing the content of Fe. Fe 3+ ion with lower valence and smaller radius than that of Zr 4+ favors to extend the bond angle of V–O–V(P) close to 180° in ZrV 1.6 P 0.4 O 7 , which is considered responsible for the normal structure at room temperature and low thermal expansion. The thermal expansion coefficients of Fe-doped ZrV 1.6 P 0.4 O 7 for Fe:Zr molar ratios from 1:9 to 4:6 are calculated to be from − 4.33 × 10 − 6 to 5.2 × 10 − 7 K − 1 by linear thermal expansion measurement. The effect of small amount of FeV 0.8 P 0.2 O 4 formation with higher content of Fe 3+ on thermal expansion coefficients of the samples is discussed.