Structural and physical properties of Sr/Ca and Mg/Ca substituted hydroxyapatite: modeling and experiments

The structural and physical properties of hydroxyapatite (HAP) with the substitution of Sr/Ca and Mg/Ca are studied. The changes in the HAP properties are studied by various methods of density functional theory calculations. The calculation of the lattice constants upon substitution of Sr/Ca in HAP compared with the experimental data shows similar increase in these parameters after substitution of Sr/Ca. The values of bulk modulus, band gap E (g), and the work function Delta phi before and after both substitutions of Sr/Ca and Mg/Ca are calculated. The changes in piezoelectric properties upon Mg/Ca substitution are obtained.