XPS, EDX and FTIR analysis of pulsed laser deposited calcium phosphate bioceramic coatings: the effects of various process parameters

Many techniques have been used to produce calcium phosphate, especially hyd roxyapatite (HA), coatings on metallic implant surfaces for improved biocom patibility. Although some techniques have produced coatings used clinically , the long-term stability of the coating/implant is still questionable. As a new technique for making HA coatings, pulsed laser deposition (PLD) shows some advantages in controlling the coatings' crystal structure and composi tion. In this study, three types of HA target and two wavelengths of laser were used to produce calcium phosphate coatings. Despite PLDs ability to im prove the crystal structure by incorporating water vapor into the depositio n process, the characterization with EDX and XPS showed that coatings had d ifferent Ca/P ratios from that of the pure HA targets, which almost assured the presence of non-HA phases. FTIR spectra also showed differences in pho sphate bands of coatings and targets although the difference in data collec ting modes might have been a factor. The observed differences might be rela ted to the differences between the surface and bulk chemistries of the coat ings. Nevertheless, when evaluating the suitability of the PLD technique fo r making HA coatings, the possibility of the formation of non-HA phases can not be excluded, although it may not necessarily be a negative factor. (C) 1999 Elsevier Science Ltd. All rights reserved.