Hydrothermal synthesis of NaNb(BO3)2 and CaPb(BO3)2, analogues of Nordenskioldine--CaSn(BO3)2

Abstract

NaNb(Bo3)2 and CaPb(B03)2, analogues of nordenskioldine were synthesized in Mourey bombs at temperatures of 330 and 450 degrees C at pressures of 121.1 atmospheres and above. NaNb(B03)2 forms colorless, tabular hexagonal crystals that are soluble in water and optically negative, n0=1.52, ne = 1.41. CaPb(Bo3)2 forms hexagonal prisms with perfect basal cleavage, n0= 1.707(5), ne= 1.601(3) with cell dimensions c= 13.38, a= 4.59 Angstroms. Further study of these products, the effect of substituting only for the Sn+4 ion in nordenskioldine, and of the system Na2O-Nb2O5-B2O3-H20 is required.