The alpha ‹-› beta phase transitions of Zn.sub.2./sub.P.sub.2./sub.O.sub.7./sub. revisited: existence of an additional intermediate phase with an incommensurately modulated structure

0435093 - FZÚ 2015 RIV DK eng J - Journal Article
Stöger, B. - Weil, M. - Dušek, Michal
The alpha ‹-› beta phase transitions of Zn₂P₂O₇ revisited: existence of an additional intermediate phase with an incommensurately modulated structure.
Acta Crystallographica Section B-Structural Science Crystal Engineering and Materials. Roč. 70, č. 3 (2014), s. 539-554. E-ISSN 2052-5206
R&D Projects: GA ČR(CZ) GA14-03276S
Institutional support: RVO:68378271
Keywords : phase transition * Zn₂P₂O₇ * single crystal structure analysis * modulated structure * Jana2006
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 2.184, year: 2014

Zn2P2O7 crystallizes in a thortveitite-like structure and features temperature-dependent polymorphism. At high temperatures (T > 500 K), the aristotype phase beta-Zn2P2O7 is stable. At lower temperatures the lock-in phase alpha1-Zn2P2O7, a sixfold superstructure with commensurate modulation vector q = (1/3, 0, 1/2), is stable. Between the stability ranges exists the intermediate, incommensurately modulated alpha2-Zn2P2O7 phase with modulation wavevector q ~ (0.33, 0, 0.40). The phase transitions were analyzed with differential scanning calorimetry and high-temperature powder and single-crystal X- ray diffraction. Different models describing the slow transition from the incommensurately modulated alpha2- to the non-modulated beta-phase were investigated.
Permanent Link: http://hdl.handle.net/11104/0239019