High-Pressure Phase Transformations in TiPO₄ : A Route to Pentacoordinated Phosphorus

Titelangaben

Bykov, Maxim ; Bykova, Elena ; Hanfland, Michael ; Liermann, Hanns-Peter ; Kremer, Reinhard K. ; Glaum, Robert ; Dubrovinsky, Leonid ; van Smaalen, Sander:
High-Pressure Phase Transformations in TiPO₄ : A Route to Pentacoordinated Phosphorus.
In: Angewandte Chemie International Edition. Bd. 55 (2016) Heft 48 . - S. 15053-15057.
ISSN 1521-3773
DOI: https://doi.org/10.1002/anie.201608530

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Abstract

Titanium(III) phosphate, TiPO₄, is a typical example of an oxyphosphorus compound containing covalent P−O bonds. Single-crystal X-ray diffraction studies of TiPO₄ reveal complex and unexpected structural and chemical behavior as a function of pressure at room temperature. A series of phase transitions lead to the high-pressure phase V, which is stable above 46 GPa and features an unusual oxygen coordination of the phosphorus atoms. TiPO₄-V is the first inorganic phosphorus-containing compound that exhibits fivefold coordination with oxygen. Up to the highest studied pressure of 56 GPa, TiPO₄-V coexists with TiPO4-IV, which is less dense and might be kinetically stabilized. Above a pressure of about 6 GPa, TiPO₄-II is found to be an incommensurately modulated phase whereas a lock-in transition at about 7 GPa leads to TiPO4-III with a fourfold superstructure compared to the structure of TiPO₄-I at ambient conditions. TiPO₄-II and TiPO₄-III are similar to the corresponding low-temperature incommensurate and commensurate magnetic phases and reflect the strong pressure dependence of the spin-Peierls interactions.