Buy article online - an online subscription or single-article purchase is required to access this article.
Download citation
Download citation
link to html
The Pb5(Cr1 − xAlx)3F19 system forms four phases. Ferroelectric phase IV, with point group 4mm, undergoes a first-order transition on heating to paraelectric phase I, point group 4/m, in the composition range 0 ≤ x ≲ 0.80. The Curie temperature varies linearly with x over this range, from 555 K at x = 0 to 365 K at x = 0.80. Phase IV transforms to monoclinic phase II in the range 0.80 ≲ x ≲ 0.88 in a first-order transition before undergoing a second-order transition at higher temperatures to phase I. In the range 0.88 ≲ x ≲ 1, phase IV initially transforms on heating to phase III, point group 4/m, in a first-order transition; at higher temperatures, this phase transforms to phase II in another first-order transition; at still higher temperatures, it transforms to phase I in a second-order transition. Multiple phase formation at x ≲ 0.80 is a result of structural instabilities that are related to the small size of the Al3+ cation and to the decreased interaction strength between the 6(sp)2 electron lone pair of Pb2+ and the residual 3d electron spin moment at the Cr-atom site as it is increasingly substituted by aluminum.

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