Buy article online - an online subscription or single-article purchase is required to access this article.
Download citation
Download citation
link to html
The breakdown of Friedel's law has been observed in backscatter Kikuchi diffraction patterns (BKDP) obtained in the scanning electron microscope (SEM) from a series of zincblende structures including GaAs, InP, GaSb, CdHgTe and the minerals sphalerite (ZnS), chalcopyrite (CuFeS2) and tetrahedrite (Cu12Sb4S13). Differences in intensities were observed between the reflections 51{\bar 1} and 5{\bar 1}{\bar 1} in InP, GaSb, CdHgTe and sphalerite, thus allowing the non-centrosymmetric point group {\bar 4}3m to be determined. In GaAs, differences in intensities were noted between {\bar 5}11 and {\bar 4}{\bar 1}. In chalcopyrite and tetrahedrite, non-equivalent intensities were observed between {\bar 2}15 and 2{\bar 1}{\bar 5} and between 3{\bar 1}{\bar 2} and 31{\bar 2}, respectively. In addition, BKDPs obtained from chalcopyrite revealed a small displacement at the point where the pair of equivalent reflections {\bar 4}06 and 460 intersect within the Kikuchi band 02{\bar 2}. The presence of this displacement together with observation of the breakdown of Friedel's law confirmed the tetragonal point group {\bar 4}2m for chalcopyrite. Although the point groups of GaAs, chalcopyrite and tetrahedrite were derived successfully using BKDPs, determination of their space groups proved unsuccessful. The superstructure reflections were invisible because the structure factors are very small. The behaviour of the invisible 200 reflection in GaAs is investigated using many-beam dynamical intensity profiles calculated across the h00 systematic row of reflections. Dynamical intensity profiles calculated across the h00 systematic rows of reflections for Ge, InP and sphalerite are also discussed.

Subscribe to Journal of Applied Crystallography

The full text of this article is available to subscribers to the journal.

If you have already registered and are using a computer listed in your registration details, please email support@iucr.org for assistance.

Buy online

You may purchase this article in PDF and/or HTML formats. For purchasers in the European Community who do not have a VAT number, VAT will be added at the local rate. Payments to the IUCr are handled by WorldPay, who will accept payment by credit card in several currencies. To purchase the article, please complete the form below (fields marked * are required), and then click on `Continue'.
E-mail address* 
Repeat e-mail address* 
(for error checking) 

Format*   PDF (US $40)
In order for VAT to be shown for your country javascript needs to be enabled.

VAT number 
(non-UK EC countries only) 
Country* 
 

Terms and conditions of use
Contact us

Follow J. Appl. Cryst.
Sign up for e-alerts
Follow J. Appl. Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds