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Materials Data on W(BrO)2 by Materials Project

WO2Br2 crystallizes in the orthorhombic Pmc2_1 space group. The structure is two-dimensional and consists of one WO2Br2 sheet oriented in the (0, 0, 1) direction. W6+ is bonded to four O2- and two equivalent Br1- atoms to form distorted corner-sharing WBr2O4 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of W–O bond distances ranging from 1.90–1.95 Å. Both W–Br bond lengths are 2.50 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent W6+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two equivalent W6+ atoms. Br1- is bonded in a single-bond geometry to one W6+ atom.

36 MATERIALS SCIENCE↗

Materials Data on W(BrO)2 by Materials Project

WO2Br2 crystallizes in the orthorhombic Pmc2_1 space group. The structure is two-dimensional and consists of one WO2Br2 sheet oriented in the (0, 0, 1) direction. W6+ is bonded to four O2- and two equivalent Br1- atoms to form distorted corner-sharing WBr2O4 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of W–O bond distances ranging from 1.87–2.00 Å. Both W–Br bond lengths are 2.50 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent W6+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two equivalent W6+ atoms. Br1- is bonded in a distorted single-bond geometry to one W6+ atom.

36 MATERIALS SCIENCE↗

Epitaxial Ferroelectric Hf 0.5 Zr 0.5 O 2 with Metallic Pyrochlore Oxide Electrodes

The synthesis of fully epitaxial ferroelectric Hf 0.5 Zr 0.5 O 2 (HZO) thin films through the use of a conducting pyrochlore oxide electrode that acts as a structural and chemical template is reported. Such pyrochlores, exemplified by Pb 2 Ir 2 O 7 (PIO) and Bi 2 Ru 2 O 7 (BRO), exhibit metallic conductivity with room-temperature resistivity of <1 mΩ cm and are closely lattice matched to yttria-stabilized zirconia substrates as well as the HZO layers grown on top of them. Evidence for epitaxy and domain formation is established with X-ray diffraction and scanning transmission electron microscopy, which show that the c-axis of the HZO film is normal to the substrate surface. The emergence of the non-polar-monoclinic phase from the polar-orthorhombic phase is observed when the HZO film thickness is ≥≈30 nm. Furthermore, thermodynamic analyses reveal the role of epitaxial strain and surface energy in stabilizing the polar phase as well as its coexistence with the non-polar-monoclinic phase as a function of film thickness.

36 MATERIALS SCIENCE↗