GROWTH OF MIXED RARE-EARTH TARTRATE CRYSTALS (Y1-XSMX)(2)(C4H4O6)(3)CENTER-DOT-ZH(2)O FROM SILICA-GELS

Experiments performed on the growth of mixed crystals of rare earth ta rtrates (Y1-xSmx)(2) (C4H4O6)(3) . zH(2)O (0 less than or equal to X l ess than or equal to 1) from silica gels at 35 similar to 40 degrees C and 25 similar to 30 degrees C employing single-diffusion technique, are discussed. The crystals maintain spherulitic morphology irrespecti ve of the value of x, concentration of upper and lower reactants, gel pH, gel age and gel temperature. Formation of Liesegang rings in this system is a temperature dependent phenomenon. It is shown that with th e increase of the value of x the system passes from Liesegang-ring phe nomenon to single-zone phenomenon. Operative mechanism of crystallizat ion in the higher (35 similar to 40 degrees C) and lower temperature r anges (25 similar to 30 degrees C) is explained. Seeded growth experim ents indicate the possibility of increasing the size of the spherulite s in the gel medium.