G. Bayer
Nov 1, 1968
Citations
0
Influential Citations
7
Citations
Journal
Journal of The Less Common Metals
Abstract
Abstract The preparation of the various modifications of orthotelluric acid is described. In addition to the previously known monoclinic and cubic modifications, a third form—tetragonal H6TeO6—could be prepared. Unit cell data have been derived from X-ray single crystal study: H6TeO6 (monoclinic): a = 6.49 4 A , b = 9.32 2 A , c = 8.33 3 A , β = 99 °43′ . H6TeO6 (cubic): a = 15.69 5 A . H6TeO6 (tetragonal): a = 15.65 2 A , c = 15.76 2 A . Indexed powder patterns are listed for all three polymorphic forms. The discrepancies found in the literature dealing with orthotelluric acid are pointed out. Monoclinic H6TeO6 is the most stable form. Cubic H6TeO6 transforms at elevated temperatures (e.g., 90 °–110 °C) to tetragonal H6TeO6 in dry atmosphere and to monoclinic H6TeO6 in water vapor-containing atmosphere. I.R. spectra and DTA/TGA investigations are discussed briefly.