Darstellung und Untersuchung einiger Schwermetall- und Ammoniumborate

Abstract

The new, until unknown, copper borate 2B2O3x3CuOx8H2O was synthesized and the already known cadmium borate 2B2O3xCdOx5H2O (4) was reproduced. The existence of B2O3xCdOx7H2O (5) could not be confirmed but instead B2O3xCdOx4H2O was found. For the first time infrared spectra and x-ray powder diffractograms of the known borates 2B2O3x3CuOx3H2O, [Cu(NH3)4]B4O7x6H2O and 2B2O3xCdOx5H2O were performed. The compound [Cu(NH3)4]B4O7x6H2O was also raman spectroscopically investigated. Infrared spectra and, if possible, x-ray powder diffractograms of the new compounds 2B2O3x3CuOx8H2O and B2O3xCdOx4H2O were done. Enhanced examinations of the known ammonium borates (NH4)2B4O7x4H2O (6, 7), alpha- NH4B5O8x4H2O (6, 8, 9, 10), beta-NH4B5O8x4H2O, (8, 11, 12) NH4B5O8x2.67H2O (11, 14, 15, 16) and NH4B5O8x2H2O (8, 13) were done and additional data were collected. X-ray powder diffractograms of these compounds were performed. For the first time alpha-NH4B5O8x4H2O, NH4B5O8x2.67H2O and NH4B5O8x2H2O were thermogravimetrically investigated and precise data of the water content were obtained. Furthermore, the thermogravimetric analysis and the differential thermogravimetric analysis allowed to define exactly the ranges of existence of alpha-NH4B5O8x4H2O, NH4B5O8x2.67H2O and NH4B5O8x2H2O. Based on the infrared and raman spectra it was possible to make predictions of the structures of the investigated ammonium borates which could be confirmed by comparison with known crystal structures.