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Materials Data on Y2(SO4)3 by Materials Project

Y2(SO4)3 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. Y3+ is bonded to six O2- atoms to form YO6 octahedra that share corners with six SO4 tetrahedra. There are a spread of Y–O bond distances ranging from 2.24–2.27 Å. There are two inequivalent S6+ sites. In the first S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with four equivalent YO6 octahedra. The corner-sharing octahedra tilt angles range from 15–26°. All S–O bond lengths are 1.48 Å. In the second S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with four equivalent YO6 octahedra. The corner-sharing octahedra tilt angles range from 5–33°. All S–O bond lengths are 1.48 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one S6+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one S6+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to one Y3+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a linear geometry to one Y3+ and one S6+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one S6+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one S6+ atom.

36 MATERIALS SCIENCE↗

Wet chemical techniques for passivation of YBa2Cu3O7(7-x)

Wet chemical techniques are described for treatment of YBa2Cu3O(7-x) surfaces, resulting in the formation of native compounds with little or no reactivity to water. Promising native compounds include CuI, BaSO4, CuS, Cu2S, and the oxalates, all of which are either insoluble or have very low solubility in water. Treatment with dilute HI results in the formation of a native iodide film which is 80-90 percent CuI with small amounts of YI3 and BaI2. Treatment with dilute H2SO4 results in the formation of a film which is 95 percent BaSO4 and 5 percent Y2(SO4)3. Cu2S is formed on the surface with a dilute Na2S solution. An oxalate film with equal amounts of Y2(C2O4)3 and BaC2O4 results from treatment with dilute oxalic acid. X-ray photoelectron spectra show no significant changes when the sulfide, sulfate, or oxalate films are dipped in water, while the iodide film shows evidence of Cu(OH)2 formation.

Vasquez, R. P.↗