Stanislaw A. Hodorowicz

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.

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.

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.

Preparation and characterization of the system BaBrxCl2-x: The structure of BaBrCl.

Abstract The variations in the lattice parameters in the BaBr x Cl 2− x system have been determined for the composition range 2.0 > x > 0.0. All phases exhibit the PbCl 2 -type orthorhombic structure and are assignable to space group Pnma . The crystallographic parameters of BaBrCl were determined by the Rietveld method from a line profile analysis of a digitized powder X-ray diffraction pattern. The anions are ordered with the bromide ion occupying the square pyramidal hole, and the chloride ion the smaller tetrahedral hole. Atomic coordinates are presented.

The Gd-Ba-Cu-O system: Phase relationships at ∼950°C in air

Abstract A systematic X-ray powder diffraction study of the Gd 2 O 3 -BaCO 3 -CuO system over the temperature range 920-980°C in ambient air is presented as a function of cation composition. In the pseudobinary regions the phases BaGd 2 O 4 , “Gd 2 Ba 4 O 7 ,” Gd 2 CuO 4 , and BaCuO 2 were observed. Mass balance data suggest that “Gd 2 Ba 4 O 7 ” is actually Gd 2 Ba 4 O 7 · CO 2 . In the pseudoternary region the phases Gd 2 BaCuO 5 , GdBa 3 Cu 2 O y , and GdBa 2 Cu 3 O 6.5+ x were identified. Although GdBa 2 Cu 3 O 6.5+ x exhibited minimal solid solution, GdBa 3 Cu 2 O y evidenced a significant solubility range. Lattice parameters are presented and from a phase analysis subsolidus relationships are constructed. The system is compared with related systems.

A preparatory and phase study of the Tm-Ba-Cu-O system

Abstract A systematic study of the Tm 2 O 3 -BaCO 3 -CuO system is presented both for different cationic molar ratios and as a function of heat treatment. Nine phases were isolated under the experimental conditions used: BaCuO 2 , BaCuO 2+ x , Tm 2 Ba 2 O 5 , Tm 2 Ba 4 O 7 , Tm 4 Cu 3 O 9 , Tm 2 Cu 2 O 5 , Tm 2 BaCuO 5 , ‘TmBa 3 Cu 2 O 6.5+ x ’ and TmBa 2 Cu 3 O 6.5+ x , The ‘TmBa 3 Cu 2 O 6.5+ x ’ phase could not be prepared pure and may represent a solid solution region. Other phases observed in the Ln -Ba-Cu-O systems for Ln =La and Eu such as the tetragonal “336” phase common to both systems could not be prepared. On the basis of the phase analysis results subsolidus phase relationships for the Tm 2 O 3 -BaCO 3 -CuO system are presented.

Phase relationships in the system SrBr2SrCl2

Abstract Strontium bromide-chloride phases (SrBrxCl2−x) in the composition region 2.00 > x > 0 were prepared and examined by the Guinier powder X-ray diffraction technique. Observed and calculated powder intensities for the compositions x = 1.60, 1.40, and 0.30 are presented. The anions assume an ordered arrangement at the first two compositions and a random arrangement at the third. Two previously unreported intermediate phases at the composition about x = 1.50 and x = 0.60, both of unknown structure, were identified and their d values are reported. SrBr2 is found to be insoluble in SrCl2.

Phases observed at 900–1100°C in the binaryLnBaO systems forLn = Dy, Ho, Er, Tm, and Yb

Abstract The compoundsLn2Ba2O5, Ln2Ba4O7, andLn4Ba3O9, forLn =Dy, Ho, Er, Tm, and Yb, have been prepared and characterized by X-ray powder diffraction. Phase interrelationships were established as a function of temperature by quenching specimens annealed at 900–1100°C. ComparableLn =Tb phases could not be prepared. Lattice parameters are presented for all phases observed.

The Dy and HoBaCuO systems: Phase relationships in air at ∼950°C and crystal chemistry comparisons

Phase equilibria in air at {approximately} 950 C are presented for the systems Ln{sub 2}O{sub 3}-BaCO{sub 3}-CuO, Ln = Dy and Ho, as a function of cation molar ratios. Symmetry data and unit cell parameters derived from powder X-ray diffraction data and phase compatibilities are presented for the seven Ln:Ba:Cu phases preparable in air between 930-980 C: 011, BaCuO{sub 2}; 202, Ln{sub 2}Cu{sub 2}O{sub 5}; 220, Ln{sub 2}Ba{sub 2}O{sub 5}; 240, Ln{sub 2}Ba{sub 4}O{sub 7}; 211, Ln{sub 2}Ba-CuO{sub 5}; 123, LnBa{sub 2}Cu{sub 3}O{sub x}; and 184, LnBa{sub 8}Cu{sub 4}O{sub y}. A solid solution region which can exist in two crystallographic modifications prevails around 184. No other compound exhibits solid solution. In the BaO-rich region phase compatibilities change above 950 C when the 220 phase converts into the 240 phase. The phases observed in the CuO-rich region of the Ln-Ba-Cu-O systems that exhibit 123-type superconductivity, Ln = La-Tm, are correlated with Ln{sup 3+} ionic radii.