High-pressure synthesis of the polymorph of layer structured compounds MNX (M = Zr, Hf; X = Cl, Br, I)

S Yamanaka; K Itoh; H Fukuoka; M Yasukawa

doi:10.1021/ic991058l

High-pressure synthesis of the polymorph of layer structured compounds MNX (M = Zr, Hf; X = Cl, Br, I)

Inorg Chem. 2000 Feb 21;39(4):806-9. doi: 10.1021/ic991058l.

Authors

S Yamanaka¹, K Itoh, H Fukuoka, M Yasukawa

Affiliation

¹ Department of Applied Chemistry, Faculty of Engineering, Hiroshima University, Higashi-Hiroshima, Japan.

PMID: 11272580
DOI: 10.1021/ic991058l

Abstract

Transition metal nitride halides MNX (M = Zr, Hf; X = Cl, Br, I) have two types of layer structured polymorphs, the alpha-form with the FeOCl type and the beta-form with the SmSI type. Both polymorphs consist of corrugated double M-N layers sandwiched between halogen layers, but with different atomic arrangements within the layers. The beta-form had been considered to be a high-temperature polymorph, because some beta-forms were obtained by thermal treatment of the corresponding alpha-forms. Here, the alpha-form was successfully transformed into the beta-form under high-pressure and high-temperature conditions; the new members of the beta-form were prepared for the first time from alpha-HfNBr, alpha-ZrNI, and alpha-HfNI using a high pressure of 3-5 GPa at 900 degrees C. The beta-form should be characterized as the high-pressure form rather than the corresponding high-temperature polymorph. This is the first high-pressure study on the polymorphs of metal nitride systems.