Growth of neodymium lanthanum heptamolybdate mixed crystals in silica gels

The optimum conditions for the growth of mixed crystals of neodymium lanthanum heptamolybdates in silica gel are found by investigating different growth parameters. A two-gel-single-tube technique coupled with seeded growth and concentration programming yields the maximum size crystals. The crystals assume spherulitic, square and octagonal platelet, and cuboid morphologies in the gel medium. Employing energy dispersive X-ray analysis, it is shown that the mixed crystals are those of neodymium lanthanum heptamolybdate in which the two rare earths combine in 1:1 ratio.