We studied the interrelationship of elastic and piezoelectric properties with the lattice structure and crystal physics of paratellurite $(\alpha -{\mathrm{TeO}}_2).\mathrm{}$ Tetragonal paratellurite ${(D}_4^4,P422)$ shows six independent elastic constants $C_{\mathrm{ijkl}},$ the associated internal friction $Q_{\mathrm{ijkl}}^{-1},$ and one piezoelectric coefficient $e_{14}.$ We determined simultaneously these material coefficients using resonant ultrasound spectroscopy coupled with laser-Doppler interferometry. Mode identification, essential for success, was done by measuring the displacement distributions on a vibrating-specimen surface. Our $C_{\mathrm{ijkl}}$ were consistent with reported values measured by conventional methods. Our $e_{14}$ exceeds the reported value by 53%. We focus on several unusual elastic properties, including a negative Poisson ratio. Considering a star-shape truss structure on the basal plane consistently explains all of them. Internal friction correlates with the $C_{\mathrm{ijkl}}$ temperature derivatives, suggesting phonon-phonon interactions as a dominant cause of the mechanical loss.

• Received 7 August 2003

DOI:https://doi.org/10.1103/PhysRevB.69.024104