Title

Novel High Pressure Hexagonal Osb2 By Mechanochemistry

Keywords

Boron; Ceramic; Mechanochemistry; Osmium

Abstract

Hexagonal OsB2, a theoretically predicted high-pressure phase, has been synthesized for the first time by a mechanochemical method, i.e., high energy ball milling. X-ray diffraction indicated that formation of hexagonal OsB2 begins after 2.5 h of milling, and the reaction reaches equilibrium after 18 h of milling. Rietveld refinement of the powder data indicated that hexagonal OsB2 crystallizes in the P63/mmc space group (No. 194) with lattice parameters of a=2.916 Å and c=7.376 Å. Transmission electron microscopy confirmed the appearance of the hexagonal OsB2 phase after high energy ball milling. in situ X-ray diffraction experiments showed that the phase is stable from -225 °C to 1050 °C. The hexagonal OsB2 powder was annealed at 1050 °C for 6 days in vacuo to improve crystallinity and remove strain induced during the mechanochemical synthesis. The structure partially converted to the orthorhombic phase (20 wt%) after fast current assisted sintering of hexagonal OsB 2 at 1500 °C for 5 min. Mechanochemical approaches to the synthesis of hard boride materials allow new phases to be produced that cannot be prepared using conventional methods. © 2014 Elsevier Inc.

Publication Date

1-1-2014

Publication Title

Journal of Solid State Chemistry

Volume

215

Number of Pages

16-21

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.jssc.2014.03.020

Socpus ID

84897490592 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84897490592

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