J. Phys. IV France 04 (1994) C2-183-C2-188
Crystal growth and characterizations of a quartz-like material : GaPO4M. COCHEZ1, J.D. FOULON1, A. IBANEZ1, A. GOIFFON1, E. PHILIPPOT1, B. CAPELLE2, A. ZARKA2, J. SCHWARTZEL3 and J. DETAINT3
1 LPMS, CNRS, 34095 Montpellier, France
2 Lab. Minér. Cristallog., Paris VI, 75252 Paris cedex, France
3 CNET PAB/BAG/MCT, 92220 Bagneux, France
This paper concerns the GaPO4 crystal growth process which consists of an alternation of the vertical reverse temperature gradient (VTG) in sulfuric acid medium and the slow heating method (SHT) in phosphoric acid. Since this process is not usable at an industrial scale, we have investigated the crystal growth in phosphoric acid medium by VTG in order to find a direct way to synthetize GaPO4 crystals. The as-grown crystals have been characterized by IR and NIR spectroscopies : the -OH content seems to decrease continuously without any plateau being observed at the last step of crystal growth as it was observed in berlinite. Moreover, both dielectric constants (ε'T) and dielectric loss (ε") have been studied in terms of temperature, frequency and -OH content. ε'T11 and ε'T33 have been found equal respectively to 6.2 and 6.6 at 20°C and 50kHz.
© EDP Sciences 1994