Twinning in the superlattice structure of CuSe, synthetic klockmannite

Abstract

Electron diffraction data have been obtained showing evidence of the hexagonal superlattice structure of CuSe, and confirming an earlier theory of twinning in this structure.

The production of a CuSe alloy and its structure determination by electron microscopy

“…However, we did not find any evidence to support Earley's (1949) conclusion that the structure is modulated along the a axis. Neither did we find any evidence of twinning as presumed by Taylor & Underwood (1960) and reported by Elliot, Bicknell & Collinge (1969 features may be due to the different methods adopted for preparation of the specimen. Several such cases are known to exist (Mader, 1966 …”

The crystal structures of Cu1•8Se, Cu3Se2, α- and γCuSe, CuSe2, and CuSe2II

“…Early (16) observed very weak reflections in single crystal patterns indicating a twelve-fold multiplicity in the a axis. The problem of the structure of the ordered modification of aCuSe has been discussed by Taylor and Underwood (17), by Lipmann (18), and by Elliott et al (19). We did not observe reflections from newly prepared specimens which could not be indexed on a Gmple hexagonal cell with a = 3.934, c = 17.217 A, although extra reflections appeared in aged specimens (1).…”

Heat capacity, structural and thermodynamic properties of synthetic klockmannite CuSe at temperatures from 5 K to 652.7 K. Enthalpy of decomposition

“…In a more detailed analysis of the superlattice, Taylor and Underwood (4) reported twinning in the (1120) plane and derived a hexagonal superlattice with A=a·(13) 1/2 . Later studies (5)(6)(7)(8)(9) confirmed the existence of this (A=a·(13) 1/2 superlattice, and revealed in addition that structural phase transitions take place on heating. (6)(7)(8)(9) According to Stevels and Jellinek, (7) a first-order transition from hexagonal to orthorhombic symmetry takes place at T=333 K, followed by a gradual change back to hexagonal symmetry on further heating.…”