摘要：The CaO-P_(2)O_(5)-SiO_(2)-MgO system presents several compounds used as biomaterials such as hydroxyapatite(HA),tricalcium phosphate(TCP)and TCP with magnesium substituting partial calcium(TCMP).Theβ-TCMP phase with whitlockite structure has interesting biological features and mechanical properties,meeting the requirements of a bioactive material for bone restoration.In this work,the production of Mg-doped TCP,β-TCMP,has been investigated by crystallization from a glass composed of 52.75 wt%3CaO·P_(2)O_(5),30 wt%SiO_(2)and 17.25 wt%MgO(i.e.,31.7 mol%CaO,10.6 mol%P_(2)O_(5),26.6 mol%MgO and 31.1 mol%SiO_(2))using heat treatments between 775°Cand 1100°Cfor up to 8 h.The devitrification process of the glass has been accompanied by differential scanning calorimetry(DSC),high-resolution X-ray diffraction(HRXRD),relative density and bending strength measurements.The characterization by HRXRD and DSC revealed the occurrence of whitlockite soon after the bulk glass preparation,a transient non-cataloged silicate between 800°Cand 1100°C,and the formation of diopside in samples treated at 1100°Cas crystalline phases.The overall crystalline fraction varied from 26%to 70%depending on the heat treatments.Furthermore,contraction of the a-axis lattice parameter and expansion of the c-axis lattice parameter of the whitlockite structure have been observed during the heat treatments,which were attributed to theβ-TCMP formation with the partial substitution of Ca^(2+)by Mg^(2+).Relative densities near 99%and 97%for the glass and glass-ceramics respectively indicated a discrete reduction as a function of the devitrification treatment.Bending strengths of 70 MPa and 120 MPa were determined for the glass and glass-ceramic material crystallized at 975°Cfor 4 h,respectively.
