X-ray diffraction study of[Zn(1−propyltetrazole)6](BF4)2single crystal

Single-crystal structure determination of ${[\mathrm{Zn}(\mathrm{ptz})}_{6}{](\mathrm{B}\mathrm{F}}_{4}{)}_{2}$ has been performed at 110 and 190 K in order to investigate the possible existence of a local structural deformation proposed by positron annihilation study of Nagai et al. [Phys. Rev. B 57, 14 119 (1998)]. A large thermal contraction along the $c$ axis with decreasing temperature is observed, while the displacement of the atoms within the $\mathrm{ab}$ plane is very small. This implies that the effect observed in the positron annihilation spectroscopies is caused by interactions involving positronium.