Structures and phase transitions in (MoO2)2P2O7.

We report structural investigations into (MoO(2))(2)P(2)O(7) using a combination of X-ray, neutron and electron diffraction, and solid-state NMR supported by first principles quantum chemical calculations. These reveal a series of phase transitions on cooling at temperatures of 377 and 325 K. The high temperature gamma-phase has connectivity consistent with that proposed by Kierkegaard at room temperature (but with improved bond length distribution), and contains 13 unique atoms in space group Pnma with lattice parameters a = 12.

Direct synthesis of cubic ZrMo2O8 followed by ultrafast in situ powder diffraction.

There has been a considerable amount of interest in negative thermal expansion (NTE) phases which are of importance, for example, in the manufacture of low or zero expansion composite materials. Cubic gamma-ZrMo(2)O(8) is of importance since it shows smooth NTE (alpha = -8 x 10(-6) K(-1) at 100 K) over a wide temperature range with no significant discontinuities as a function of temperature. The material has long been thought to be metastable at all temperatures and has previously only been produced under kinetic control by routes such as the careful dehydration of ZrMo(2)O(7)(OH)(2).

Complex superstructures of Mo2P4O15.

We report structural studies on Mo(2)P(4)O(15) over the temperature range 16-731 K, which show that it is considerably more complex than revealed by earlier work. Its low-temperature structure has lattice parameters a = 24.1134(6) A, b = 19.

Mo2P4O15--the most complex oxide structure solved by single crystal methods?

We report the crystal structure and phase transitions of Mo2P4O15 which, despite a simple chemical formula, has 441 crystallographically unique atoms in its asymmetric unit and thus has the most complex structure of any extended oxide reported to date.