Harry A. Eick

The synthesis, structure and characterization of SrMoO2.615N0.4

Abstract The structure of the cubic perovskite-type oxide-nitride SrMoO 2.6 N 0.4 , synthesized from SrMoO 4 and NH 3 (g) at 750°C, has been determined by neutron diffraction. Structural and chemical analyses suggest that the average Mo oxidation number is +4.4; nitrogen and oxygen atoms are distributed statistically in the anion sites. Magnetic susceptibility and electrical conductivity measurements suggest metallic behavior for this oxide-nitride; IR data are also presented. So that 16 N-enriched specimens could be synthesized, relationships in the synthesis reaction between total system pressure, partial pressure of NH 3 (g), reaction time and the nitrogen content of the product SrMo(O,N) 3 were determined. These results are presented and discussed.

The preparation and some properties of europium bromides and hydrated bromides

Abstract Europium dibromide was prepared by dehydration and decomposition of an europium tribomide hexahydrate-ammonium bromide matrix and single crystals were grown by vapor transport techniques. Anhydrous europium tribromide was prepared by reaction of the dibromide with bromine at bromine pressures of between 12 and 70 atm. Powder and single crystal X-ray diffraction data indicate tetragonal symmetry for EuBr2 ( a = 11·574±0·006, c = 7·098±0·005 A ) and orthorhombic symmetry for EuBr3 ( a = 9·12±0·01, b = 12·66±0·02, c = 4·013±0·005 A ). Monoclinic EuBr3·6 H2O ( a = 10·025±0·008, b = 6·757±0·005, c = 8·164±0·007 A , β = 93·48±0·06° ) and orthorhombic EuBr2·H2O ( a = 11·46±0·02, b = 4·291±0·005, c = 9·20±0·01 A ) have also been characterized. Observed and calculated X-ray diffraction powder intensities for the dibromide structure are presented and discussed.

The PrBaCuO and NdBaCuO systems: Phase relationships at ∼950°C

Systematic X-ray powder diffraction studies of the Nd{sub 2}O{sub 3}-BaCO{sub 3}-CuO and PrO{sub x}-BaCO{sub 3}-CuO systems at {approximately} 950{degree}C in air are presented as a function of cation molar ratios. In the pseudo-binary regions BaCuO{sub 2} was observed in both systems; Pr{sub 2}CuO{sub 4} and BaPrO{sub 3}, and Nd{sub 2}CuO{sub 4} and BaNd{sub 2}O{sub 4}, were observed in the Pr and Nd systems, respectively. BaPr{sub 2}O{sub 4} could be prepared only in a reducing atmosphere. In the pseudo-ternary regions the 123 and 336 phases were observed in the Pr system; the 123, 336, and 311 phases were observed in the Nd system. In the Pr system extensive solid-solution prevails between the 110, 123, and 336 phases and between the latter two phases and CuO. In the Nd system solid-solution was observed between 311, and 123, and 336 phases, and between the latter two phases and CuO.

Solvolytic decomposition studies on mixed phases: Synthesis of the anti-Fe2P-type BaX2 (X Cl, Br) from BaX2LnX3 phases☆

Metastable anti-Fe2P-forms of BaCl2 and BaBr2 have been synthesized by solvolytic decomposition reactions effected on mixed-cationic BaCl2 · y LnCl3 (Ln  La, Sm) with pyridine and BaBr2 · x LnBr3 (Ln  La, Nd) with tetrahydrofuran (THF) respectively. The phase, Ba9Ln5Br33 (Ln  La, Nd) is found to be isostructural with Eu14Cl33. The mixed Ba-Ln-Cl analogue has a related structure. The reaction mechanism is discussed.

The high-temperature Eu2O3BaCO3CuO-atmospheric oxygen phase diagram: Phase characterization in the 90 K superconducting region

Abstract A comprehensive study of the Eu2O3CuOBaCO3 (950°C BaCO3 decomposition products) system has been effected on intimately mixed specimens which were subsequently fired both in air and in pure oxygen. In the binary oxide regions the phases Eu2BaO4, Eu2CuO4, and BaCuO2+x were observed. In the ternary oxide region the phases Eu2BaCuO5, EuBa2Cu3O6.5+x, and Eu3Ba3Cu6O13.5+x were observed. The phases were characterized by X-ray diffraction; structure type and lattice parameter data are reported. Only for EuBa2Cu3O6.5+x in the orthorhombic modification was 90 K superconductivity observed.

Phase relationships in the SmBaCuO system at ∼950°C

Abstract A systematic X-ray powder diffraction study of the Sm 2 O 3 BaCO 3 CuO system over the temperature range ∼920–980°C is presented as a function of cationic molar ratios. In the pseudobinary regions the phases BaSm 2 O 4 , Sm 2 CuO 4 , and BaCuO 2 were observed; in the pseudoternary region Sm 2 BaCuO 5 , SmBa 3 Cu 2 O z , Sm 3 Ba 3 Cu 6 O y , and SmBa 2 Cu 3 O y were identified. A solid solution region was found in the vicinity of SmBa 2 Cu 3 O y . Lattice parameters are presented for each compound detected. A pseudoternary phase diagram is presented: subsolidus relationships are indicated. This system is compared with related lanthanoid-barium-copper oxide systems; only the europium system exhibits comparable phases.

Synthesis and structure of Li3Ba2TaN4

A new quaternary nitride, Li3Ba2TaN4, has been synthesized from Li, Ba and Ta metals under flowing N2 at high temperature. The structure, as determined by single crystal X-ray diffraction techniques, is monoclinic, space group C2c, Z=4, with lattice parameters a=11.294(2) A, b=5.678(1) A, c=11.350(2) A, and β=121.407(7)°. Refinement based upon F2 yielded R2=0.052 and wR2=0.074 (for comparison, a refinement based upon F yielded R1=0.032). The Ta and one of the two independent Li ions are tetrahedrally coordinated by N anions; the Li tetrahedra are distorted. By sharing edges, the Ta and Li tetrahedra form chains which are linked together by the remaining Li ions to form the three-dimensional structure.

The Yb2O3 and Lu2O3BaO(BaCO3)CuO systems: compounds and phase compatibilities in air at 940–980 °C

Abstract Phase compatibilities in air at around 950 °C are presented for the systems Ln 2 O 3 BaCO 3 CuO, LnYb and Lu, as a function of cation molar ratios. The Lu-“123” oxide could not be synthesized. Seven Ln:Ba:Cu phases were preparable in air in the range 940–980 °C: 011, BaCuO 2 ; 202, Ln 2 Cu 2 O 5 ; 220, Ln 2 Ba 2 O 5 ; 240, Ln 2 Ba 4 O 7 ; 211, Ln 2 BaCuO 5 ; 123, only for YbBa 2 Cu 3 O χ ; and 132, ‘LnBa 3 Cu 2 O γ ’. In the BaO-rich region, phase compatibilities change above 950 °C when the ‘220’ phase converts into the ‘240’ phase.

An X-ray diffraction study of the SrBrxI2−x system

Abstract The mixed halogen phases SrBrxI2−x, for which 2.00 > x > 0 were prepared both by heating weighed masses of pure SrBr2 and SrI2 in sealed evacuated quartz ampoules and by cocrystallization from absolute ethanol. The reaction products were examined by X-ray powder diffraction methods. Five distinct regions were observed in the phase diagram. The crystallographic characteristics of phases representative of the single phase regions, SrBr2SrBr1.60I0.40, SrBr1.40I0.60SrBr0.80I1.20, and SrBr0.30I1.70SrI2, are presented, and the anion distributions in the crystal structures are deduced on the basis of X-ray powder diffraction intensities.

Vaporization reactions in the ytterbium–fluorine system

The vaporization and sublimation reactions for the ytterbium fluoride system have been investigated by mass loss, x‐ray powder diffraction, elemental analysis, and mass spectrometry. When YbF2.00 is heated in vacuum, it decomposes to give a metal rich vapor and a metal deficient residue until the composition YbF2.40(4) is reached. The following equilibrium reactions were established: YbF2.40(s,l) = (0.60)YbF2(g) + (0.40)YbF3(g), Reaction (a); and YbF3.00(s,l) = (0.05)YbF2.40(s,l) + (0.95)YbF3(g) + (0.03) F (g), Reaction (b). % A target collection Knudsen effusion method was used to determine vapor pressures for the above reactions. From the slope–intercept data the following enthalpy and entropy changes with associated standard deviations were derived at the median temperatures: For Reaction (a), ΔH°1597 = (96.9±1.1) kcal mol−1 and ΔS°1597 = (36.83±0.67 %cal mol−1⋅K−1; for Reaction (b), ΔH°1568 = (91.19±0.41) kcal mol−1 and ΔS°1568 = (37.28±0.26) cal mole−1⋅K−1. Estimated and reported thermodynamic functi...