Structural Changes of Hydroxylapatite during Plasma Spraying: Raman and NMR Spectroscopy Results

Functional osseoconductive coatings based on hydroxylapatite (HAp) and applied preferentially by atmospheric plasma spraying to medical implant surfaces are a mainstay of modern implantology. During contact with the hot jet, HAp particles melt incongruently undergo complex dehydration decomposition reactions that alter their phase composition crystallographic symmetry, thus, physical biological properties coatings. Surface analytical methods such as laser-Raman nuclear magnetic resonance (NMR) spectroscopies useful tools assess structural changes imposed heat treatment during flight along jet. In this contribution, controversial information is highlighted existence or non-existence oxyapatite, i.e., fully dehydrated thermodynamically stable compound.