Temperature Dependence of Elastic, Dielectric, and Piezoelectric Constants in TeO2 Single Crystals

Abstract

All of the elastic stiffness constants except c13 have been found to decrease almost linearly with temperature between −120° and 120°C. The constant c13 reaches the maximum in the vicinity of 0°C, above which it also decreases with temperature. On the other hand, the effective elastic constant (c11–c12)/2, which corresponds to the exceptionally slow shear wave propagating along [110], increases with temperature. The shear wave propagating in the (001) plane making angle of 35.9° with the X axis has zero temperature coefficient of velocity. Acoustic absorptions for several sound modes vary within 1 dB/cm for both the longitudinal wave (measured at 36 MHz) and shear wave (48 MHz) in the measured temperature range. Both real and imaginary parts of the dielectric constants increase monotonically with temperature, while the piezoelectric constant d14 decreases in the temperature range between −150° and 180°C.

Experimental verification of Herring’s theory of anharmonic phonon relaxation:TeO2

“…1͒. This crossover temperature seems reasonable in relation to the Debye temperature of TeO 2 , which from acoustic 14 and crystallographic data 17 is estimated at roughly 200 K. Already around T co , therefore, the thermally excited phonon spectrum, which in the Debye approximation scales with 2 /͓exp(ប/k B T)Ϫ1͔, reaches its maximum near the zone boundary.…”

“…2. The figure, which results from solving the Christoffel equations 2 with known elastic constants, [14][15][16] and covers the central part of the ͑110͒ plane in the Brillouin zone, shows constant-energy contours for the fast-transverse ͑FT͒ and slow-transverse ͑ST͒ phonon branches. Let us consider the process LϩST→FT, which is forbidden in isotropic crystals, and let us denote the wave vectors of the three phonons by q 0 , q 1 , and q 2 , and similarly their angular frequencies by 0 , 1 , and 2 .…”

Analysis of the frequency response of a TeO{sub 2} slow shear wave acousto-optic cell exposed to radiation

“…From these equations, it is clear that if (:)2 decreases, the coefficient, IlP will decrease, and the overall diffracted beam intensity will decrease. It is clear that other physical parameters in the equation for ( : ) are functions of temperature, however, the variations of these parameters are relatively small [16] and collectively would tend to increase the value of ( : ) with an increase in temperature. It would be beneficial to study the acoustooptic figure of merit, M2, as a function of temperature.…”

Characterization of Temperature Field Distribution in Large-Size Paratellurite Crystals Applied in Acousto-Optic Devices

“…According to [10] the constants of elastic stiness c ik decrease with the increase of the temperature, whereas the eective constant (c 11 c 12 )/2 increases, and nally the coecient of acousto-optic quality M 2 decreases with temperature by about 4 × 10 and electric power applied to the piezoelectric transducer (0.53.5 W). The lter was intended for astrophysical spectral studies and was described in detail elsewhere [11,12].…”

“…The paratellurite material refractive indexes for ordinary n o and extraordinary n e beams most important in acousto-optics are characterized (at the wavelength of λ = 1.06µm) by the following temperature dependences [3,5]: n o (T ) = 2.20386 + 7.2 × 10 −6 T and n e (T ) = 2.34792 + 3.9 × 10 −6 T . The coecient of volume expansion according to [10] is α = 4 × 10…”