OH defects in synthetic xenotime (YPO4)
Abe, Takeyasu; Kuribayashi, Takahiro; Nakamura, Michihiko
European Journal of Mineralogy Volume 28 Number 3 (2016), p. 641 - 648
published: Jun 1, 2016
ArtNo. ESP147052803012, Price: 29.00 €
The polarized infrared spectra of hydrogen-containing xenotime (YPO4) were measured to obtain information on its OH defects. Sample syntheses were conducted at 1.0 GPa using a piston-cylinder apparatus under water-saturated conditions. By lowering the temperature at a rate of 10 C/h from 1200 to 800°C, xenotime single crystals up to ~300 μm in length were obtained. A sharp OH stretching vibrational band was observed at 3302 cm-1. Using a molar absorption coefficient of 111 217 L mol-1 cm-2 , the H2 O concentration in the sample was estimated as 20 10 ppm. The OH band showed strong infrared absorption perpendicular to the c -axis and weak absorption parallel to the c -axis. According to electrostatic considerations and assuming the presence of Y3+ or P5+ vacancy, possible orientations of the O H bonds were estimated. We propose that the OH incorporation mechanism in synthetic xenotime is controlled by Y3+ vacancy ( YY ↔ VY = 3Hi).