Thermal destruction of polymer-salt compositions containing d-metals in the form of oxygen-bearing anions

The behavior of polymer-salt compositions consisting of water-soluble nonio nogenic polymers and salts containing d-metal-oxygen anions was studied in the range 20-700 degrees C by thermal analysis, conductometry, optical micr oscopy, x-ray diffraction, and dilatometry. The salts used were ammonium he ptamolybdate, ammonium B-paratungstate, and ammonium metavanadate and the p olymers were poly(vinyl alcohol), polyvinylpyrrolidone, and methyl cellulos e. The films prepared by drying the precursor compositions were found to re tain, during heating, the polymer-salt molecular complexes formed at room t emperature. The mechanism of the thermal destruction of the salts in the po lymer-salt films was shown to differ from that in pure salts because, in th e films, mutual stabilization of the polymer and salt took place. In the po lymer-salt compositions, oxides were formed directly from amorphous precurs ors, without formation of intermediates, characteristic of the decompositio n of pure salts. The oxides thus prepared consisted of fine particles and e xhibited photochromic effect due to partial reduction of metal ions.