Crystal structure of ZnWO(4) scintillator material in the range of 3-1423 K

The behaviour of the crystal structure of ZnWO(4) was investigated by means of synchrotron and neutron powder diffraction in the range of 3-300 K. Thermal analysis showed the sample's melting around 1486 K upon heating and subsequent solidification at 1442 K upon cooling. Therefore, the structure was also investigated at 1423 K by means of neutron diffraction. It is found that the compound adopts the wolframite structure type over the whole temperature range investigated. The lattice parameters and volume of ZnWO(4) at low temperatures were parametrized on the basis of the first order Grüneisen approximation and a Debye model for an internal energy. The expansivities along the a- and b-axes adopt similar values and saturate close to 8 × 10(-6) K(-1), whereas the expansion along the c-axis is much smaller and shows no saturation up to 300 K. The minimum expansivity corresponds to the direction close to the c-axis where edge-sharing linkages of octahedra occur.