Peculiarities in thermal evolution of precipitated amorphous calcium phosphates with an initial Ca/P ratio of 1:1.

Thermal evolution of amorphous calcium phosphate (ACP) powder from a fast nitrate synthesis with a Ca/P ratio of 1:1 were studied in the range of 20-980 °C. The powder consisted of amorphous dicalcium phosphate anhydrate (CaHPO) after heating to 200 °C. CaHPO gradually condensed to amorphous calcium pyrophosphate CaPO (CPP) between 200 to 620 °C.

Study of structure of calcium phosphate materials by means of electron spin resonance.

Structure of γ-irradiated calcium phosphates synthesized in different conditions was studied by means of ESR. It has been shown that amorphous and nanocrystalline calcium phosphates have qualitatively different ESR spectra. The new paramagnetic center in hydroxyapatite (HA) has been found.

Structural and compositional features of amorphous calcium phosphate at the early stage of precipitation.

Precipitates formed at an early stage (during the first 6 h) of the hydroxyapatite crystallization of a solution were studied. A nitrous synthesis was used (0.583M (NH(4))(2)HPO(4) and 0.

Thermal impurity reactions and structural changes in slightly carbonated hydroxyapatite.

Lattice and surface impurity reactions and structural changes induced by them in slightly carbonated hydroxyapatite (SCHA) treated at 25-1100 degrees C were comprehensively studied. The SCHA was processed by a conventional wet synthesis at a high possible temperature(96 degrees C) using ammonium containing parent reagents. IR-spectroscopy, XRD, TG-DTA technique and mass spectrometric thermal analysis (MSTA) were employed for characterization of the samples.