Reactions of the gas-phase synthesis of tin vanadates, borates, and molybdates were studied. Standard enthalpies of formation and atomization of gaseous salts SnV 2 O 6 , SnB 2 O 4 , Sn 2 B 2 O 5 , SnMoO 4 , Sn 2 MoO 5 , and SnMo 2 O 7 were determined.

Knowledge of the structures of gaseous oxyacid salts of the M(m) XO(n) type is of interest for understanding the nature of chemical bonds. Gaseous VPO(2) and VPO(3) have been identified by Knudsen effusion mass spectrometry during the vaporization of mixtures of V(2)O(3) and alkali earth phosphates from molybdenum and tungsten effusion cells. The structures and molecular parameters of the gaseous vanadium phosphates under study were determined using quantum chemical calculations. On the basis of equilibrium constants measured for gas-phase reactions, the standard formation enthalpies were determined to be -273 ± 17 and -615 ± 16 kJ·mol(-1) for VPO(2) and VPO(3), respectively.

A number of gaseous oxyacid salts have been identified by Knudsen effusion mass spectrometry, while vaporizing Cr(2)O(3) and mixtures of Cr(2)O(3)+Nb(2)O(5), Cr(2)O(3)+Ta(2)O(5), Cr(2)O(3)+BaO, and Cr(2)O(3)+Mg(2)P(2)O(7) from molybdenum and tungsten cells. The stabilities of the gaseous molecules CrMoO(3), CrMoO(4), CrMoO(5), CrWO(3), CrWO(4), CrWO(5), CrNbO(3), CrTaO(3), CrPO(2), CrPO(3), BaCrO(2) and BaCrO(3) were deduced from the measurements. The thermodynamic properties of this gaseous chromium-containing species are summarized. Prediction is tentatively made of the stability of as-yet unstudied gaseous molecules.

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The thermodynamic functions found in the Yb2O3-ZrO2 system at 2400 K, such as the activities of components and the Gibbs energy of formation, displayed negative deviation from ideality. Mutual agreement was observed between the experimental thermodynamic values and the results of calculations based on the CALPHAD approach.