Aleksandra Matraszek

Phase Composition and Vaporization Study of LaGa1–xAlxO3, 0 ≤x≤ 1, and La0.9Sr0.1Ga0.8–xAlxMg0.2O2.85, x= 0.1, 0.2, 0.3

The vaporization of the LaGa1–xAlxO3 solid solution, 0 ≤x≤ 1, of the perovskite structure, was investigated using Knudsen effusion mass spectrometry in the temperature range of 1623–1928 K. The partial pressures of the gaseous species O2, Ga, GaO, Ga2O, and LaO were determined for the samples investigated. The equilibrium partial pressures were used for the computation of thermodynamic activities of Ga2O3 and La2O3 at 1800 K. Thermodynamic activities of Al2O3 were obtained using Gibbs–Duhem integration. Gibbs energies of formation of the solid-solution LaGa1–xAlxO3 resulted from the thermodynamic activities of the oxide components. Samples of the chemical composition La0.9Sr0.1Ga0.8–xAlxMg0.2O2.85, x= 0.1, 0.2, 0.3, were of practical importance in solid oxide fuel cell (SOFC) technology and also were investigated. The influence of the aluminum concentration in the perovskite phase on the thermodynamic activity and volatility of Ga2O3 is presented and implications for the potential use of this material in SOFC technology are discussed.

Supramolecular stores of acetic acid—An alternative for metal-organic frameworks

A series of new complexes: [M(quin-2-c)(2)(H(2)O)(2)]x 4CH(3)COOH (M=Mn(2+), Co(2+) or Ni(2+), quin-2-c is quinoline-2-carboxylate ion) have been synthesized and characterized by X-ray single crystal study. The crystals of the complexes reveal very interesting 1D structures comprising acetic acid molecules. The processes of re- and desolvation of acetic acid by the manganese complex in mild conditions have been studied. The de- and resolvated materials were characterized by elemental analysis, IR spectroscopy and XRD study. The results show that binding of acetic acid is reversible and stoichiometric.

Vaporization and Thermochemical Study of SrCeO3(s) and SrCe0.95Yb0.05O3(s) by Knudsen Effusion Mass Spectrometry

The vaporization of samples in the SrO-CeO2 system was investigated by the use of Knudsen effusion mass spectrometry in the temperature range of 1494 K – 1988 K. Partial pressures of the gaseous species O2, CeO2, Sr, and SrO were determined over the samples investigated. The partial pressures of the species were used for the evaluation of thermodynamic activities of CeO2 and SrO in the samples at 1800 K. The enthalpy of formation of SrCeO3(s) was obtained as fH°(298 K) = -1644 ± 21 kJ mol-1. The Gibbs energy of formation of SrCeO3(s) from SrO(s) and CeO2(s) resulted as fG°(1800 K) = -12.5 ± 2.8 kJ mol-1 for the phase field {SrCeO3 + ss of SrO in CeO2} and fG°(1800 K) = -13.7 ± 2.1 kJ mol-1 for the phase field {SrCeO3 + SrO}. The influence of the Yb concentration in the perovskite phase SrCe0.95Yb0.05O3 on the CeO2(s) activity was studied as well. The thermodynamic properties obtained in the present study are discussed on the basis of the data available in literature.