[en] The enthalpy of Cs₂ZrO₃ has been derived from its enthalpy of solution in HF.100H₂O, as measured calorimetrically, in combination with auxiliary values. For the standard molar enthalpy of formation of Cs₂ZrO₃ the value Δsub(f)H⁰sub(m)(298.15 K) = -(1584.8 +- 1.9) kJ.mol^-1 has been found. (author)

No abstract available

[en] Enthalpies of solution of (UO²)²Cl³, U²O²Cl⁵, UOCl², and UOCl in H²SO⁴(aq) have been measured calorimetrically. In combination with the enthalpies of solution of ß-UO³ and UCl⁴ in this solvent the standard enthalpies of formation of these uranium oxide chlorides have been derived. The values obtained for δsub(f)H₀sub(m)(s, 298.15 K)/(kJ.mol^-₁) are: (UO²)²Cl³, -(2404.5 +- 1.9); U²O²Cl⁵, -(2197.4 +-4.2); UOCl², -(1069.3 +- 2.7); UOCl, -(832.9 +- 4.2). (author)

No abstract available

[en] The preparation of Cs₂RuO₄(s) have been described and its standard molar enthalpy of formation has been derived from its enthalpy of solution in 1.0 mol·dm^-3 NaOH in water, in combination with auxiliary values. The value Δ_fH_m⁰(295.15 K) = -(964.6±5.3) kJ·mol^-1 has been obtained. (author)

[en] In the zirconium-rich part of the Zr-Te system the stoichiometric compounds Zr₅Te₄ and Zr₃Te exist. The crystal structures of both compounds have been investigated. The crystal structure of Zr₅Te₄ has been resolved by Rietveld refinement of neutron powder diffraction data. It has a tetragonal body-centered unit cell with lattice parameters a = 1.07649(6) nm, c = 0.38403(3) nm, spacegroup I4/m, and is isostructural with Ti₅Te₄. The profile agreement factors are R_p = 4.38%, R_wp = 5.91% and S = 2.22. The crystal structure of Zr₃Te has been resolved by Rietveld refinement of the X-ray powder diffraction data. It has a tetragonal body-centered unit cell with lattice parameters a = 1.13382(6) nm and c = 0.56265(5) nm, space-group I anti 4, isostructural with Ni₃P, with profile agreement factors R_p = 12.5, R_wp = 13.6% and S = 1.06. The structural similarities between both compounds are discussed

[en] Strontium zirconium disilicate, SrZrSi₂O₇, M_r=347.011, monoclinic, P2₁/c, T=295 K, a=7.7617(9), b=8.0713(10), c=10.0559(11) A, β=111.90(1) , V=584.51(7) A³, Z=4, D_x=3.935(1) Mg.m^-3, D_exp=3.928(22) Mg.m^-3 (T=294.85 K). Rietveld refinement using neutron powder diffraction data [λ=2.5717(3) A, F(000)=252.45 fm, μR=0.11, 295 contributing reflections] resulted in R_wp=2.72%. The structure can be described by alternately stacking layers containing the ZrO₆ octahedra and layers formed by the Si₂O₇ groups, parallel to (001). Elongated cages are formed for Sr with distorted SrO₈ dodecahedrons. The Si₂O₇ groups are in a nearly eclipsed configuration. The title compound is isostructural with the high temperature form of NaFeP₂O₇. (orig.)

[en] The perovskite-type BaUO₃ structure has been investigated by X-ray and neutron diffraction. The Ba/U ratio, the (Ba, Sr)/U ratio, and the oxygen stoichiometry in Ba_1+yUO_3+x were varied, and the integral enthalpies of formation determined by solution calorimetry. In addition, equilibrium oxygen partial pressures were measured using a reversible EMF cell. The chemical defect mechanism is discussed, and it is shown that a continuous series BaUO₃-Ba_1+yUO_3+x-Ba₃UO₆ exist in which uranium vacancies are gradually filled up with barium ions, whereas uranium is oxidized via the pentavalent to the hexavalent state in Ba₃UO₆(=Ba₂(Ba, U)O₆). (orig.)

[en] Rietveld refinement of strontium zirconium disilicate, SrZrSi₂O₇, using neutron powder diffraction data [λ = 2.57167(3) A, F(000) = 252.45, μR = 0.11, 295 contributing reflections] resulted in R_wp = 2.72%. The structure can be described as alternate layers, containing the ZrO₆ octahedra and formed by the Si₂O₇ groups, stacked parallel to [001]. Elongated cages are formed for Sr, which coordinates to give distorted SrO₈ dodecahedra. The Si₂O₇ groups are in a nearly eclipsed conformation. The title compound is isostructural with the high-temperature form of NaFeP₂O₇. (orig.)