Interaction of hafnium tetrafluoride with ammonium fluoride in aqueous solution

Abstract

1. The interaction between hafnium tetrafluoride and ammonium fluoride in aqueous solution was studied by methods of separate potentiometric and conductometric titration, microscopic observations, and X-ray diffraction study. 2. Under the conditions of the investigation, the formation of two compounds was detected: NH4HfF5·–/3H2O and (NH4)2HfF6. 3. The thermal stability of these compounds was studied by differential thermal analysis and by a thermogravimetric method. NH4HfF5 2/3H2O loses water at 110°, and splits out ammonium fluoride at 386°. (NH4)HfF6 splits out the first molecule of ammonium fluoride at 336°, and the second at 386°.