Thermal decomposition of ammonium molybdates

Abstract

The thermal behavior of ammonium molybdates, i.e. (NH 4 ) 6 Mo 7 O 24 •4H 2 O (1) and (NH 4 ) 2 MoO 4 (2), was studied in inert (N 2 ) and oxidizing (air) atmospheres by TG/DTA-MS, XRD, FTIR and SEM. The thermal decomposition sequence of 2 had similarities to 1; however, there were significant differences as well. When both of them were annealed, NH 3 and H 2 O were released parallel, and in air the asevolved NH 3 was burnt partially into NO and N 2 O. In both atmospheres, while 1 decomposed in four steps, the thermal decomposition of 2 involved 5 steps. In the case of 1, the intermediate products were Most decomposition steps were endothermic, except for the last step around 400 °C, where crystallization from the residual amorphous phase had an exothermic heat effect. In addition, the combustion of NH 3 also changed the DTA curve into exothermic in some cases. The morphology of the final products was characterized by 1-5 m sheet-like particles, except for annealing 2 in N 2 , when 0.5-1 m thick and 5-10 m long needle-shaped particles were detected.

Flame Spray Synthesis and Ammonia Sensing Properties of Pure α-MoO3 Nanosheets

“…A sharp drop in the weight is noticed at 325 ∘ C, indicating the decomposition of ammonium salt and formation of -MoO 3 . The decomposition temperature for (NH 4 ) 2 (Mo 4 O 13 ) was found to be in accordance with the literature [21], where an endothermic reaction was reported at 317 ∘ C; NH 3 and H 2 O were the decomposition products and -MoO 3 was reported as the final product. No change was noticed upon further increasing the temperature to 550 ∘ C or during the cooling process indicating formation of a thermally stable phase.…”

Flame retardancy and smoke suppression properties of flexible polyurethane foams containing an aluminum phosphate microcapsule

“…In recent years, little attention has been focused on the development of nanocomposites with an inorganic aluminum compound that contains phosphate, ammonium, molybdate. 14 It is challenge to achieve high ame retardancy and non-dripping for PU foam simultaneously by the multilayer phase (aluminum compound that contains phosphate, ammonium, molybdate).…”

Successive ionic layer deposition of Fe3O4HxMoO4nH2O composite nanolayers and their superparamagnetic properties

“…4) a water molecules are included in composition of nanolayer, which can be identified by the valence band (3400 cm −1 ) and the deformation band (1640 cm −1 ). The band at 594 cm −1 may be assigned to valence vibrations of Fe-O bonds in magnetite Fe 3 O 4 [20], and bands at 950-750 cm −1 region connected with valence vibrations of Mo-O bonds in molybdate-anions [21]. For the explanation the obtained results it can be suggested the following schemes of chemical reactions on the surface of silicon.…”