The solubility of Ba(NO3)(2) and Sr(NO3)(2) crystals in aqueous solution from 25 to 65 degreesC has been determined by both an optical interferometer and a weight technique. A Mach-Zehnder interferometer was used for measuring the concentration distribution of Ba(NO3)(2) and Sr(NO3)(2) near the solid/liquid interface during crystal growth and dissolution. A fringe carrier technique was introduced to visualize more clearly the boundary layer and to solve the concentration distribution. Crystals were successfully grown with sizes larger than 60 mm x 60 mm x 70 mm by a temperature cooling method. The BaxSr1-x(NO3)(2) crystal was also nucleated and grown. The Raman spectra of BaxSr1-x(NO3)(2) indicate that the barium ions probably degrade the properties of Sr(NO3)(2). (C) 2003 Elsevier Ltd. All rights reserved.