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High-Pressure Phase Transformations in TiPO4 : A Route to Pentacoordinated Phosphorus
Maxim Bykov1,2,3, Elena Bykova1, Michael Hanfland4
1Bayerisches Geoinstitut, University of Bayreuth, 95440, Bayreuth, Germany.
Angewandte Chemie (International Ed. in English)
|November 1, 2016
Summary
Titanium(III) phosphate (TiPO4) undergoes significant structural changes under high pressure, revealing a novel five-coordinate phosphorus-oxygen structure. These findings challenge existing models of oxyphosphorus compounds.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Crystallography
Background:
- Titanium(III) phosphate (TiPO4) is an oxyphosphorus compound with covalent P-O bonds.
- Understanding its behavior under pressure is crucial for materials science.
Purpose of the Study:
- To investigate the structural and chemical evolution of TiPO4 under high pressure at room temperature.
- To characterize the novel high-pressure phases and their properties.
Main Methods:
- Single-crystal X-ray diffraction was employed to study TiPO4.
- Experiments were conducted at room temperature across a range of pressures up to 56 GPa.
Main Results:
- Multiple phase transitions were observed, leading to phase V above 46 GPa.
- Phase V exhibits an unprecedented five-fold oxygen coordination for phosphorus.
- TiPO4-II and TiPO4-III phases show incommensurate and commensurate modulations, respectively, linked to spin-Peierls interactions.
Conclusions:
- TiPO4 exhibits complex structural transformations under pressure, including a unique five-coordinate phosphorus-oxygen arrangement.
- The study provides the first example of such coordination in inorganic phosphorus compounds.
- Pressure significantly influences the electronic and structural properties, affecting spin-Peierls interactions.
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