Heat treatment-induced phase transformations of materials in a system of calcium phosphates and magnesium phosphates with (Ca + Mg)/P = 2

We have studied the effect of heat treatment in a wide temperature range (from 300 to 1500°C) on the phase composition, heat effects and weight loss of powder materials in a system of calcium phosphates and magnesium phosphates with (Ca + Mg)/P = 2. The results demonstrate that crystalline magnesium-substituted whitlockite phases begin to form at temperatures above 600°C. Raising the heat treatment temperature reduces the degree of magnesium substitution for calcium in the structure of the magnesium-substituted whitlockite. Tetracalcium phosphate, a high-temperature phase, is formed through apatite phase recrystallization.