Thermal polycondensation of ammonium paratungstate, (NH4)10[W12O40(OH)2].4H2O |
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Authors: | A B Kiss T Nemeth E Szalanczy |
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Affiliation: | (1) Research Institute for Technical Physics of the Hungarian Academy of Sciences, Budapest, Hungary;(2) Research Institute, United Incandescent Lamp and Electricity Co., Budapest, Hungary |
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Abstract: | Connected with the examination of the thermal polycondensation of ammonium paratungstate pentahydrate the chemical and morphological
properties of intermediate phases formed during the thermal decomposition of APT have been investigated. We have studied the
pH and the turbidity of the aqueous solutions of the intermediate phases, the solubility of the phases, and their rehydratation
capability as well as the morphology of the crystallite granules and the grain size distribution. These properties of the
original APT have been related to the same properties of the products of decomposition formed between different temperature
ranges. The results obtained show unambiguously that each of the above mentioned properties suddenly changes in the temperature
range 225 to 250°C. This temperature range coincides with the formation temperature of a new phase called APT II. The most
probable formula of APT II is (NH4)8 H2W13O43(OH)2]·H2O. |
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