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Materials Data on Eu2O3 by Materials Project

Eu2O3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Eu3+ sites. In the first Eu3+ site, Eu3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Eu–O bond distances ranging from 2.33–2.78 Å. In the second Eu3+ site, Eu3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Eu–O bond distances ranging from 2.31–2.59 Å. In the third Eu3+ site, Eu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Eu–O bond distances ranging from 2.26–2.56 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four Eu3+ atoms to form distorted OEu4 trigonal pyramids that share a cornercorner with one OEu6 octahedra, corners with two equivalent OEu5 square pyramids, corners with nine OEu4 tetrahedra, corners with two equivalent OEu4 trigonal pyramids, edges with three equivalent OEu5 square pyramids, and edges with two equivalent OEu4 trigonal pyramids. The corner-sharing octahedral tilt angles are 38°. In the second O2- site, O2- is bonded to five Eu3+ atoms to form distorted OEu5 square pyramids that share corners with seven OEu4 tetrahedra, corners with two equivalent OEu4 trigonal pyramids, edges with two equivalent OEu6 octahedra, edges with two equivalent OEu5 square pyramids, edges with three OEu4 tetrahedra, and edges with three equivalent OEu4 trigonal pyramids. In the third O2- site, O2- is bonded to six Eu3+ atoms to form OEu6 octahedra that share corners with six OEu4 tetrahedra, corners with two equivalent OEu4 trigonal pyramids, edges with two equivalent OEu6 octahedra, edges with four equivalent OEu5 square pyramids, and edges with six OEu4 tetrahedra. In the fourth O2- site, O2- is bonded to four Eu3+ atoms to form distorted OEu4 tetrahedra that share corners with two equivalent OEu6 octahedra, corners with two equivalent OEu5 square pyramids, corners with four OEu4 tetrahedra, corners with six equivalent OEu4 trigonal pyramids, an edgeedge with one OEu6 octahedra, edges with two equivalent OEu5 square pyramids, and an edgeedge with one OEu4 tetrahedra. The corner-sharing octahedral tilt angles are 11°. In the fifth O2- site, O2- is bonded to four Eu3+ atoms to form OEu4 tetrahedra that share a cornercorner with one OEu6 octahedra, corners with five equivalent OEu5 square pyramids, corners with four OEu4 tetrahedra, corners with three equivalent OEu4 trigonal pyramids, edges with two equivalent OEu6 octahedra, an edgeedge with one OEu5 square pyramid, and edges with two equivalent OEu4 tetrahedra. The corner-sharing octahedral tilt angles are 48°.

36 MATERIALS SCIENCE↗

Materials Data on Eu2O3 by Materials Project

Eu2O3 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Eu3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Eu–O bond distances ranging from 2.28–2.64 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to six equivalent Eu3+ atoms to form OEu6 octahedra that share corners with twelve equivalent OEu4 tetrahedra, edges with six equivalent OEu6 octahedra, and edges with six equivalent OEu4 tetrahedra. In the second O2- site, O2- is bonded to four equivalent Eu3+ atoms to form OEu4 tetrahedra that share corners with six equivalent OEu6 octahedra, corners with six equivalent OEu4 tetrahedra, edges with three equivalent OEu6 octahedra, and edges with three equivalent OEu4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–56°.

36 MATERIALS SCIENCE↗

Materials Data on Eu2O3 by Materials Project

Eu2O3 is Corundum-like structured and crystallizes in the cubic Ia-3 space group. The structure is three-dimensional. there are two inequivalent Eu3+ sites. In the first Eu3+ site, Eu3+ is bonded to six equivalent O2- atoms to form a mixture of edge and corner-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles are 56°. All Eu–O bond lengths are 2.36 Å. In the second Eu3+ site, Eu3+ is bonded to six equivalent O2- atoms to form a mixture of distorted edge and corner-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Eu–O bond distances ranging from 2.32–2.39 Å. O2- is bonded to four Eu3+ atoms to form a mixture of distorted edge and corner-sharing OEu4 tetrahedra.

36 MATERIALS SCIENCE↗

Structure-property relations in lanthanide borate glasses

Glass formation in the system Ln2O3-B2O3 (Ln = Nd, Sm) was studied. Glasses could be formed in the range from 0 to 28 mol pct rare-earth oxide (Ln2O3), but liquid immiscibility in these systems limits the range of homogeneous glasses to 0 to 1.5 and 25 to 28 mol pct Ln2O3. The infrared spectra indicate that the rare-earth-rich glasses are structurally similar to rare-earth metaborates (LnB3O6) which contain (B3O6)-infinity chains. The variation in density, transformation temperature, thermal expansion coefficient, and transformation-range viscosity of these glasses with the size of the rare-earth ion is discussed. Glasses near the metaborate composition have a transformation temperature of about 700 C, which is high for binary borate glasses. Glasses could not be formed in the systems Eu2O3-, Gd2O3-, Ho2O3-, and Er2O3-B2O3, even by quenching at 1300 C/s. The sudden lack of glass formation in the system Ln2O3-B2O3 with Ln(3+) ions smaller than Sm(3+) is explained on the basis of the size effect of the Ln(3+) ion on the stability of (B3O6)-infinity chains in these metaborates.

Chakraborty, I. N.↗