Estimating the standard thermodynamic functions of rare-earth and alkali-earth manganitoferrites LnMIIMnFeO5.5 (Ln = La, Nd, Gd, Dy, Er; MII = Mg, Ca, Sr, Ba)

The standard enthalpies of formation of LnM^IIMnFeO^5.5 manganitoferrites (Ln is a rare-earth element, and M^II is an alkali-earth metal) were estimated by the developed method of calculation. Their standard entropies were calculated by the method of ionic increments, and their standard Gibbs energies of formation were determined by the Gibbs-Helmholtz equation.     

Study of the heat capacity of the derivatives C21H16N2O and C21H19N2O2Br of the alkaloid harmine

Temperature dependences of the heat capacity of the alkaloid harmine derivatives 9-methoxy-2-phenyl-11H-indolysine[8,7-b]indole (C₂₁H₁₆N₂O) and N-(2)-phenacylharminium bromide C₂₁H₁₉N₂O₂Br wer studied by the experimental calorimetry method.     

Thermodynamic properties of anthraquinone derivatives

The enthalpies of solution of a series of anthraquinone derivatives in dioxane at various dilutions were determined by isothermal calorimetry.     

Synthesis and X-ray diffraction study of nanostructured particles of cuprate manganites LaM 2 II CuMnO6 (MII = Mg,Ca, Sr,Ba)

Cuprate manganites of the composition LaM ₂ ^II CuMnO₆ (M^II = Mg, Ca, Sr, Ba) were synthesized from lanthanum, copper(II), and manganese(III) oxides and alkaline-earth metal carbonates by high-temperature solid-phase synthesis. By grinding the produced substances in a ball mill, their nanostructured particles were obtained, the sizes of which were determined with an electron microscope. Indexing the X-ray powder diffraction patterns of the cuprate manganites established that all of them crystallize in the cubic system with the following unit cell parameters: LaMg₂CuMnO₆: a = 15.523 ± 0.033 Å, Z = 6, V ⁰ = 3740.48 ± 0.10 ų, V _el.cell ⁰ = 623.41 ± 0.03ų, ρ_X-ray = 5.81 g/cm³, and ρ_pycn = 5.75 ± 0.06 g/cm³; LaCa₂CuMnO₆: a = 15.422 ± 0.058 Å, Z = 4, V ⁰ = 3667.94 ± 0.174 ų, V _el.cell ⁰ = 916.48 ± 0.04 ų, ρ_X-ray = 3.77 g/cm³, and ρ_pycn = 3.72 ± 0.05 g/cm³; LaSr₂CuMnO₆: a = 15.275 ± 0.049 Å, Z = 4, V ⁰ = 3564.05 ± 0.27 ų, V _el.cell ⁰ = 891.01 ± 0.07 ų, ρ_X-ray = 4.31 g/cm³, and ρ_pycn = 4.25 ± 0.05 g/cm³; and LaBa₂CuMnO₆: a = 15.589 ± 0.029 Å, Z = 4, V ⁰ = 3788.39 ± 0.09 ų, V _el.cell ⁰ = 947.10 ± 0.02 ų, ρ_X-ray = 4.74 g/cm³, and ρ_pycn = 4.70 ± 0.05 g/cm³. The data of an IR spectroscopic study of the cuprate manganites were presented.     

X-Ray diffraction data for new ferrites ErMFe<Subscript>2</Subscript>O<Subscript>5</Subscript> (M = Li,Na, K)

New ferrites ErMFe₂O₅ (M = Li, Na, K) were synthesized from erbium and iron(III) oxides and lithium, sodium, and potassium carbonates by solid-state annealing. According to X-ray powder diffraction, these compounds crystallize in the orthorhombic system with the following unit cell parameters: ErLiFe₂O₅, a = 10.510 Å, b = 10.776 Å, c = 14.270 Å, V ⁰ = 1616.16 ų; Z = 16, V _subcell ⁰ = 101.01 ų, ρ_X = 6.01 g/cm³, ρ_pycn = 5.97 ± 0.05 g/cm³; ErNaFe₂O₅, a = 10.519 Å, b = 10.785 Å, c = 15.510 Å, V ⁰ = 1759.56 ų, Z = 16, V _subcell ⁰ = 109.90 ų, ρ_X = 5.77 g/cm³, ρ_pycn = 5.72 ± 0.08 g/cm³; ErKFe₂O₅, a = 10.050 Å, b = 11.320 Å, c = 15.480 Å, V ⁰ = 1937.33 ų, Z = 16, V _subcell ⁰ = 121.08 ų, ρ_X = 5.46 g/cm³, ρ_pycn = 5.41 ± 0.04 g/cm³.     

Thermodynamic Properties of Anabasine Hydrochloride and Its Analogs

The heats of solution of anabasine hydrochloride C10H14N2HCl and of the reaction of its aqueous solution with crystalline AgNO₃ at various dilutions were determined. The standard enthalpies of formation of anabasine hydrochloride and its 36 analogs were calculated. The temperature dependence of the anabasine hydrochloride heat capacity was studied within the 173-448 K range.     

Thermodynamic properties of solutions of imidazolidine-2-thione and potassium isopropylxanthate in ethanol and characteristics of individual compounds

The enthalpies of solution of imidazolidine-2-thione and potassium isopropylxanthate in ethanol and their isobaric heat capacity in the range from 173 to (T _{m ? 100}) K were measured by calorimetry at 298.15 K. The standard enthalpies of formation, combustion, and melting of these compounds were estimated.     

Synthesis and X-ray diffraction study of the LaMg<Superscript>I</Superscript>Mg(CrO<Subscript>3</Subscript>)<Subscript>2</Subscript> (M<Superscript>I</Superscript> = Li,Na, K) compounds

Ternary chromites of the composition LaM^IMg(CrO₃)₂ (M^I = Li, Na, K) were synthesized for the first time by ceramic technology from stoichiometric amounts of high purity grade La₂O₃; pure for analysis grade Li₂CO₃, Na₂CO₃, K₂CO₃, and MgCO₃; and chemically pure grade Cr₂O₃. Using X-ray diffractometry, it has been established that compounds are crystallized in cubic and tetragonal crystal systems, and parameters of their crystal lattices have been determined.     

Thermodynamic Properties of Zincate-Manganites of LaM<Subscript>2</Subscript> <Superscript>II</Superscript>ZnMnO<Subscript>6</Subscript> (М<Superscript>II</Superscript> = Mg,Ca, Sr,Ba) Composition

Temperature dependences of the heat capacity of new zincate-manganites of LaM₂^IIZnMnO₆ (M^II = Mg, Ca, Sr, Ba) composition are studied via experimental calorimetry in the interval of 298.15–673 K. It is found that all compounds have λ-shape effects on the curve of dependence C_p° ~ ?(T) with respect to phase transitions of the second kind. Equations for the temperature dependence of the heat capacity are derived with allowance for phase transition temperatures, and thermodynamic functions H°(T) ? H°(298.15), S°(T) and Φ^xx(T) are calculated on the basis of experimental data on C_p°(T) and the calculated S°(298.15) value.     

X-ray powder diffraction features of manganites DyM 3I M 3II Mn4O12 (MI = Li, Na, K; MII = Mg, Ba)

Manganites DyM₃^IMg₃Mn₄O₁₂ and DyM₃^IBa₃Mn₄O₁₂ (M^I = Li, Na, K) were synthesized by the solid-state reaction of dysprosium and manganese(III) oxides and magnesium and corresponding alkali metal carbonates. The X-ray powder diffraction studies showed that the crystals are orthozhombic with the following unit cell parameters and densities: DyLi₃Mg₃Mn₄O₁₂—a = 10.88 ?, b = 10.73 ?, c = 19.63 ?, V ⁰ = 1656.2 ?³, Z = 8, ρ_calc = 5.36 g/cm³, ρ_pycn = 5.11 ± 0.05 g/cm³; DyNaMg₃Mn₄O₁₂—a = 10.55 ?, b = 10.72 ?, c = 18.28 ?, V ⁰ = 2067.4 ?³, Z = 8, ρ_calc = 4.60 g/cm³, ρ_pycn = 4.88 ± 0.09 g/cm³; DyK₃Mg₃Mn₄O₁₂—a = 10.56 ?, b = 10.72 ?, c = 20.89 ?, V ⁰ = 2206.0 ?³, Z = 8, ρ_calc = 4.60 g/cm³, ρ_pycn = 4.92 ± 0.06 g/cm³; DyLi₃Ba₃Mn₄O₁₂—a = 10.53 ?, b = 10.69 ?, c = 21.28 ?, V ⁰ = 2395.4 ?³, Z = 8, ρ_calc = 5.58 g/cm³, ρ_pycn = 5.98 ± 0.12 g/cm³; DyNa₃Ba₃Mn₄O₁₂—a = 10.53 ?, b = 10.74 ?, c = 23.00 ?, V ⁰ = 2602.3 ?³, Z = 8, ρ_calc = 5.39 g/cm³, ρ_pycn = 5.30 ± 0.07 g/cm³; DyK₃Ba₃Mn₄O₁₂—a = 10.52 ?, b = 10.75 ?, c = 25.69 ?, V ⁰ = 2905.2 ?³, Z = 8, ρ_calc = 5.04 g/cm³, ρ_pycn = 5.00 ± 0.18 g/cm³.