  Elastic neutron scattering on a single crystal and powder X-ray diffraction
measurements were carried out to investigate how the crystal structure evolves
as a function of temperature in the Weyl semimetal WTe$_{2}$. A sharp
transition from the low-temperature orthorhombic phase (T$_{d}$) to the
high-temperature monoclinic phase (1T$^{\prime}$) was observed at ambient
pressure in the single crystal near $\sim$565 K. Unlike in MoTe$_{2}$, the
solid-solid transition from T$_{d}$ to 1T$^{\prime}$ occurs without the cell
doubling of the intermediate T$_{d}^{*}$ phase with AABB (or ABBA) layer
stacking. In powders however, the thermal transition from the T$_{d}$ to the
1T$^{\prime}$ phase is broadened and a two phase coexistence was observed until
700K, well above the structural transition.
