DIRECT GROWTH-RATE MEASUREMENT OF HYDROXYAPATITE SINGLE-CRYSTAL BY MOIRE PHASE-SHIFT INTERFEROMETRY

The growth rate of the hydroxyapatite (0001) face in pseudophysiologic al solution was measured directly for the first time by Moire phase sh ift interferometry. Common-path-type interferometry and a newly develo ped signal processor used for the phase shift technique enabled the pr ecise and stable measurement of growth rates. It was determined that t he growth rate was strongly time-dependent. The growth rate gradually decreased with time and finally ceased although the concentration of t he solution remained constant. The thickness of the layer grown on the seed crystal was about 500-700 nm, while the growth rate during initi al growth stages was of the order of 10(-2) nm/s. respectively. Detail ed surface morphology was observed by atomic force microscopy (AFM), i ndicating that the growth mode was multiple two-dimensional nucleation .