The final step in this preparation involved two different ways of cooling. The fist one, cooling the sample from 1550 °C inside the furnace to 512 °C and heating at 512 °C/24 h followed by slow cooling to room temperature at a rate of 3 °C/min. This combined heat treatment procedure was required to ensure that the equilibrium conditions were achieved. The second material was quenched from 1550 °C in liquid nitrogen in order to obtain at room temperature as a mestastable phase the high temperature phase of the system Ca2SiO4–Ca3(PO4)2.The heat treatment temperatures were carefully selected bearing in mind information provided by the 2CaOSiO2–7CaOP2O52SiO2 sub-system existing within the binary system of Ca3(PO4)2–Ca2SiO4.35 The final samples were cut from the bars obtained, which measured 7 mm in diameter and 1.5 mm in thickness.