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HR‐TEM imaging and image simulation of vacancy clusters in brown diamond
Author(s) -
Barnes R.,
Bangert U.,
Martineau P.
Publication year - 2006
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200671111
Subject(s) - diamond , vacancy defect , lattice (music) , impurity , diamond type , crystal (programming language) , crystal structure , diamond cubic , chemical physics , materials science , synthetic diamond , high resolution , crystallography , condensed matter physics , mineralogy , molecular physics , chemistry , material properties of diamond , geology , physics , metallurgy , remote sensing , organic chemistry , acoustics , computer science , programming language
Diamonds, although famous for their sparkling colourless nature, can exhibit many colours due to imperfections in the crystal lattice. Brown diamonds, while not the favourite variety, have attracted much attention and mystery in finding the origin of the colour. The defect, which is not impurity related, can be removed with HPHT treatment. Collections of vacancies have been suggested as the source of the colour by theoretical calculations [1] and positron annihilation experiments [2, 3]. Therefore, simulations have been carried out to determine whether the suggested sizes of vacancy clusters could be seen in HR‐TEM. Substantial contrast has been revealed in defocused images. In light of the simulations, experimental defocus series have been acquired in lattice resolution for brown and colourless, natural and synthetic type IIa diamonds. A small‐scale patchiness is apparent in the lattice images of brown but not of colourless diamond. Further analysis, including simulations of multiple vacancy clusters, suggests this contrast in brown diamond could be due to many irregularly distributed vacancy clusters. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)