Beige materials for the ceramic industry: AlxVyFe1-xP1-yO4 (0.0 ≤ x ≤ 0.3, 0.0 ≤ y ≤ 0.1) solid solutions

Abstract

AlxVyFe1-xP1-yO4 (0.0 ≤ x ≤ 0.3, 0.0 ≤ y ≤ 0.1) compositions were synthesized via the chemical co-precipitation method. At 500 °C, α-FePO4 berlinite crystallizes together with FePO4 tridymite, Fe(III) occupying tetrahedral sites in both structures. The variation in the unit cell confirms the formation of solid solutions with α-FePO4 berlinite structure. These AlxVyFe1-xP1-yO4 (0.0 ≤ x ≤ 0.3, 0.0 ≤ y ≤ 0.1) solid solutions are stable between 800 and 1000 °C and when x > 0.2 at 1200 °C. Fe7P6O24 with Fe(II) and Fe(III) is detected in the compositions with the highest amount of Fe(III) at 1200 °C. The materials are paramagnetic between 100 and 300 K and the variation in their magnetic susceptibilities fits the Curie-Weiss law with negative Weiss constants (antiferromagnetism). At 1200 °C, the presence of small amounts of Fe(II) is associated with a slight decrease in μeff. The presence of vanadium in samples (y > 0) decreases their μeff. Optimal beige materials to work without sample fusion at 1200 °C are reported.