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DOE OSTI2020

Materials Data on BaO2 by Materials Project

BaO2 is hexagonal omega structure structured and crystallizes in the orthorhombic Cmmm space group. The structure is two-dimensional and consists of two BaO2 sheets oriented in the (0, 1, 0) direction. Ba is bonded to eight equivalent O atoms to form a mixture of edge and face-sharing BaO8 hexagonal bipyramids. All Ba–O bond lengths are 2.77 Å. O is bonded in a distorted pentagonal planar geometry to four equivalent Ba and one O atom. The O–O bond length is 1.52 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on BaO2 by Materials Project

BaO2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba is bonded in a distorted q4 geometry to ten equivalent O atoms. There are two shorter (2.74 Å) and eight longer (2.83 Å) Ba–O bond lengths. O is bonded in a 6-coordinate geometry to five equivalent Ba and one O atom. The O–O bond length is 1.50 Å.

36 MATERIALS SCIENCE↗

NASA NTRS1988

Characterization of Ba2YCu3O(7-x) prepared in an inert atmosphere

Reaction data, X-ray data, and critical temperature measurements have been used to show that superconducting Ba2YCu3O(7-x) can be produced in an inert atmosphere using BaO2 as the barium source. Weight loss data are presented for samples produced in O2 and N2. The use of BaO2 is found to result in decreased levels of intergrain BaCO3. The necessity for total inert atmosphere handling and tighter control of the carbon content of starting materials is pointed out. It is shown that materials made with BaO2 and handled in inert atmospheres can be used to improve the J sub c of melt processed materials.

Hepp, A. F.↗

NASA NTRS1988

Improved synthesis of ceramic superconductors with alkaline earth peroxides - Synthesis and processing of Ba2YCu3O(7-x)

Synthesis processes for the preparation of ceramic conductors Ba2YCu3O(7-x) from BaO2 or BaCO3 in flowing O2 or N2 are described, and the characteristics of the materials produced in these processes are compared. Results of EDAX, XRD, SEM, and dc resistivity analyses demonstrated that superconducting materials made from BaO2 were more homogeneous, denser, and more metallic than materials produced from BaCO3, because of the higher reactivity of BaO2. Potential applications of this processes are discussed.

Hepp, A. F.↗

NASA NTRS1988

Advantages of barium peroxide in the powder synthesis of perovskite superconductors

This paper compares reaction chemistry, material processing, and material characteristics for the solid state reaction using BaCO3 or BaO2 in the synthesis of perovskite superconductors. Results are presented for weight loss and X-ray diffraction, sample morphology and homogeneity as monitored by SEM and EDS, and the superconductivity critical temperature and ac susceptibility. Greater mass density, increased sample homogeneity, lower resistance, and improved reproducibility for material are found when BaO32 is used.

Hepp, A. F.↗