Phase relations in a barium-rich high-temperature region (25-45 mol% CuO, 900-1100 deg. C) of the BaO-CuO{sub x} system
- Institute of Solid State Physics of the RAS, Chernogolovka, Moscow District, 142432 (Russian Federation)
The phase relations have been studied in the BaO-CuO{sub x} system in the range of 25.0-45.0 mol% CuO at 900-1100 deg. C at P(O{sub 2})=21 kPa (air) by visual polythermal analysis (VPA), powder X-ray diffraction (XRD), electron diffraction (ED) with simultaneous energy-dispersive X-ray (EDX) elemental analysis in a transmission electron microscope (TEM), and iodometric chemical analysis. The discrete deviations 2.02 (101:50), 2.04 (102:50), 2.10 (105:50) of Ba/Cu (Ba:Cu) composition from the stoichiometric ratio 2:1 have been found for the known Ba{sub 2}CuO{sub 3+{delta}} oxides in the subsolidus region 900-970 deg. C. Unit cell parameters of the 101:50 orthorhombic oxide, 102:50 tetragonal one, 105:50 orthorhombic one are, respectively, a=4.049, b=3.899, c=13.034 A; a=3.985, c=12.968 A; a=4.087, b=3.897 and c=12.950 A. ED patterns of the 101:50, 102:50, 105:50 oxides show characteristic supercell reflections with the respective vector 1/60[5 4 0], {approx}2/11<1 1 0> and 1/6[2 0 0]. Oxides of the 2:1, 7:4, 5:3 and 23:20 compositions have been found in the crystallization region 970-1050 deg. C. Unit cell parameters of the 2:1 orthorhombic oxide are a=4.095, b=3.795, c=13.165 A. Interplanar spacings and X-ray characteristic peak intensities of the 7:4, 5:3 and 23:20 oxides are given. Oxides 2:1 and 7:4 melt pseudocongruently at 1020 and 1005 deg. C, oxides 5:3 and 23:20 melt incongruently at 995 and 980 deg. C, respectively. A diagram of the phase relations in the studied region of the BaO-CuO{sub x} system has been constructed, whose structure is considered as the total projection of phase states of the system existing for different x. - Graphical Abstract: A diagram of phase relations in the BaO-CuO{sub x} system in the range of 30.0-45.0 mol% CuO at 900-1050 deg. C at P(O{sub 2})=21 kPa (air) constructed on the data obtained by visual polythermal analysis (the liquidus line), XRD and ED with elemental analysis. Highlights: > A combination of physical-chemical and structural methods was used. > New discrete oxides have been found. > The diagram reflects the total projection of phase states at different x.
- OSTI ID:
- 21580156
- Journal Information:
- Journal of Solid State Chemistry, Vol. 184, Issue 7; Other Information: DOI: 10.1016/j.jssc.2011.05.028; PII: S0022-4596(11)00277-5; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BARIUM
BARIUM OXIDES
COPPER OXIDES
CRYSTALLIZATION
ELECTRON DIFFRACTION
IODOMETRY
ORTHORHOMBIC LATTICES
PHASE DIAGRAMS
TEMPERATURE RANGE 0400-1000 K
TRANSMISSION ELECTRON MICROSCOPY
X RADIATION
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
BARIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL ANALYSIS
COHERENT SCATTERING
COPPER COMPOUNDS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIAGRAMS
DIFFRACTION
ELECTROMAGNETIC RADIATION
ELECTRON MICROSCOPY
ELEMENTS
INFORMATION
IONIZING RADIATIONS
METALS
MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
QUANTITATIVE CHEMICAL ANALYSIS
RADIATIONS
SCATTERING
TEMPERATURE RANGE
TITRATION
TRANSITION ELEMENT COMPOUNDS
VOLUMETRIC ANALYSIS