The results of the synthesis and identification of complex compounds of hexamethylenetetramine (CH2)6N4 (HMTA) with tungsten phosphate metallates are presented. The processes and crystalline products of thermal decomposition of compounds with the general formula Cat5[PW11O39Z(HMTA)]∙nH2O, where Cat = Na+, NH_4^ + ; Z = Co2+, Ni2+, Zn2+; n = 10–13 have been studied by differential scanning calorimetry, IR spectroscopy, and X-ray powder diffraction. The schemes for their thermolysis have been established. It has been shown that ammonium salts during thermolysis form phases of the composition ZO⋅0.5P2O5⋅11WO3 or Z6/73P6/73W66/73O3 with the structure of phosphotungsten bronze. The decomposition products of sodium salts are a mixture of phases with the structures of sodium tungstates Na2W2O7 and Na2W4O13. The research results can be used to predict thermal transformations and the composition of thermolysis products of similar complexes of HMTA and tungsten phosphate metallates of other 3d elements.

Polyoxotungstosilicates with the general formulas Cat4[SiW12O40] · mH2O and Cat6[SiW11O39Ni(H2O)] · nH2O were synthesized, where Cat = Rb+, Cs+, (CH3)4N+. By means of IR spectroscopy and x-ray diffraction analysis, it was shown that the compounds have the Keggin anion structure. The thermolysis of the obtained compounds within the temperature range of 600 – 800°C resulted in the formation of previously unknown pyrochlore-structure phases Rb12/13Si2/13W22/13Ni2/13O6 and Cs12/13Si2/13W22/13Ni2/13O6 with the with the unit cell parameters a of 10.284 and 10.309 Å, as well as phases with tungsten bronze structure Rb12/20Si3/20W36/20O6 and Si3/38W36/38O3. The synthesis of tungsten silicates with pyrochlore and tungsten bronze structure through thermolysis of polyoxotungstosilicates reduces the temperature of their preparation to 600 – 650°C and heating time to 1 h, thus extending the ranges of chemical compositions and their morphological diversity.

The physicochemical processes occurring in glasses of the PbO–CdO–SiO2–B2O3–Al2O3 system after high-temperature contact with oxides of various metals—CuO, NiO, Al2O3, TiO2, Nb2O5, and WO3, as well as the electrical resistance of the obtained glasses—are studied by X-ray phase analysis, infrared spectroscopy, and electron paramagnetic resonance. It is established that these properties are determined by the acid-base and redox properties of the oxides and glasses, which directly depend on the content of the O2– ion in each specific composition.

We present the results of the synthesis, investigation of thermal decomposition, and identification of thermolysis products of tetramethylammonium and tetraethylammonium salts of phosphotungstate metalates with cobalt, nickel, or copper in the coordination sphere of the complex, which are promising compounds in the fields of materials science, catalysis, and medicine. Compounds with the Keggin anion ([(CH 3 ) 4 N] 5 [PW 11 O 39 Z(H 2 O)]⋅ n H 2 O and [(C 2 H 5 ) 4 N] 5 [PW 11 O 39 Z(H 2 O)]⋅ m H 2 O, where Z = Co 2+ , Ni 2+ , or Cu 2+ ) have been synthesized from aqueous solutions. Their thermal decomposition and crystalline decomposition products have been characterized by differential scanning calorimetry (DSC), thermogravimetry, IR spectroscopy, X-ray powder diffraction (XRD), and electron microscopy. A general scheme of their thermolysis has been proposed. It has been shown that phosphorus, cobalt, nickel, and copper ions enter ZO ⋅ 0.5P 2 O 5 ⋅11WO 3 or Z 6 / 73 P 6 / 73 W 66 / 73 O 3 phases with the phosphor tungsten bronze structure; phases with similar chemical composition have not been documented previously. The results of this work can appear useful in predicting the thermal properties and phase compositions of thermolysis products of similar polyoxometalates in order to manufacture new related materials.

This paper reports the synthesis of compounds with the pyrochlore and hexagonal tungsten bronze structures via thermal decomposition of heteropolyoxometalates. Using aqueous solutions, we have synthesized tungstophosphatometalates with the Keggin structure and the general formula Ct5[PW11O39(H2O)Z]⋅nH2O, where Ct = Rb+ or Cs+ and Z = Co2+, Ni2+, or Cu2+. We have studied the thermal decomposition of these compounds and identified their thermolysis products: phases with the pyrochlore and hexagonal tungsten bronze structures. Our results confirm that phosphorus, cobalt, nickel, and copper ions become incorporated into the pyrochlore and hexagonal tungsten bronze structures of the CtnxPxZxW2–2xO6 compounds. No phases with similar chemical compositions have been reported previously. Their synthesis temperature has been lowered by 200°C and the calcination time has been reduced by a factor of 2 in comparison with conventional synthesis methods. The proposed schemes of thermolysis of rubidium and cesium tungstophosphatometalates will be useful for predicting the thermal properties and phase composition of thermolysis products of analogous heteropolyoxometalates in designing new inorganic materials based on them.

The information on the compatibility of lead–boron–silicate glass of various compositions and ruthenium(IV) oxide compounds is systematized. The chemical processes occurring between them are established in terms of the theory of the acid-base interaction. The informative indicators that determine the direction of such interaction are the acidity, ionic potential, or orbital electronegativity of the components included in the composite materials. The established regularities can be used for selecting the composition of lead- and cadmium-free glass in the development of advanced ruthenium resistors and ruthenium-containing materials.