Effect of heat treatment on pulsed laser deposited amorphous calcium phosphate coatings.
Amorphous calcium phosphate coatings were produced by pulsed laser deposition from targets of nonstoichiometric hydroxyapatite (Ca/P = 1.70) at a low substrate temperature of 300 degrees C. They were heated in air at different temperatures: 300, 450, 525 and 650 degrees C. Chemical and structural analyses of these coatings were performed using X-ray diffraction (XRD), FTIR, and SEM, XRD analysis of the as-deposited and heated coatings revealed that their crystallinity improved as heat treatment temperature increased. The main phase was apatitic, with some beta-tricalcium phosphate in the coatings heated at 525 and 600 degrees C. In the apatitic phase there was some carbonate substitution for phosphate and hydroxyl ions at 450 degrees C and almost solely for phosphate at 525 and 600 degrees C as identified by FTIR. This was accompanied by a higher hydroxyl content at 525 and 600 degrees C. At 450 degrees C a texture on the coating surface was observable by SEM that was attributable to a calcium hydroxide and calcite formation by XRD. These phases almost disappeared at 600 degrees C, probably due to a transformation into calcium oxide.
García
F
F
Departamento de Física Aplicada, Universidade de Vigo, Spain.
Arias
J L
JL
Mayor
B
B
Pou
J
J
Rehman
I
I
Knowles
J
J
Best
S
S
León
B
B
Pérez-Amor
M
M
Bonfield
W
W
D002130:Calcium Phosphates; D006358:Hot Temperature; D007834:Lasers; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C519480:amorphous calcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous