J. Phys. IV France 04 (1994) C2-177-C2-182
Pressure effects on the solubility and crystal growth of α-quartzF. LAFON and G. DEMAZEAU
Laboratoire de Chimie du Solide du CNRS et Interface Hautes Pressions, LCS-CNRS-ENSCPB, Université Bordeaux I, 33405 Talence cedex, France
Industrial α-quartz growth mainly refers to hydrothermal reactions with dissolution stage mass transport and crystallization at the interface between aqueous solution/seed. Experimental investigations on α-quartz dissolution with high pressure in different aqueous solutions (NaOH-lM, Na2CO3-1M) have underlined that : pressure parameter increases the solubility limit (sl) of α-quartz for each investigated solution. In a high pressure range (200≤P≤350MPa), Na2CO3(1M) seems a better solvent than NaOH(1M). Experimental studies on α-quartz growth rate versus pressure in both aqueous solutions NaOH(1M) and Na2CO3(1M) indicates the existence of a maximum for the kinetics of crystallization. In the case of Na2CO3(1M) a more complex variation of the growth rate is observed . The use of pressure beyond 200 MPa could open new developments in α-quartz crystal-growth through : (i) a better knowledge of conventional solvents (NaOH and Na2CO3) in such a pressure domain, (ii) the investigation of new solvents more appropriate to reduce the concentration of chemical defects.
© EDP Sciences 1994