Issue 12, 1997

Modelling phase changes in the potassium titanyl phosphate system

Abstract

Potassium titanyl phosphate (KTiOPO4 , KTP) is the principal member of a group of isomorphous compounds, some of which have important non-linear optical properties. These structures have the acentric space group symmetry Pna21 and are ferroelectric. KTP itself undergoes a first-order, displacive isosymmetric phase change at 5.8 GPa at ambient temperature, as well as a second-order, displacive, order–disorder change to a paraelectric phase, with space group Pnan, under ambient pressure at 934 °C. Eight of these materials have been modelled using the static lattice modelling techniques in the GULP code. The materials modelled are: potassium, thallium and rubidium titanyl phosphates; potassium stannyl phosphate; potassium vanadyl phosphate; and potassium, rubidium and caesium titanyl arsenates. The modelling of the effects of pressure (based on the ambient pressure structures only) reproduces the isosymmetric phase change in KTP, and predicts similar pressure-driven phase changes for seven of the eight structures; only CsTiOAsO4 fails to demonstrate this phase change. Certain of the high pressure structures modelled are rotationally twinned relative to their ambient pressure progenitor structures, in a manner in accord with suggestions in the literature. It did not prove possible to model the temperature-driven phase change using a static, ordered model; this problem is ascribed to disorder in the cation positions in the high-temperature phase.

Article information

Article type
Paper

J. Mater. Chem., 1997,7, 2537-2542

Modelling phase changes in the potassium titanyl phosphate system

L. Glasser and C. Richard A. Catlow, J. Mater. Chem., 1997, 7, 2537 DOI: 10.1039/A704337F

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements