Anharmonicity of zone-centre optical phonons: Raman spectra of the isomorphous ?-quartz, berlinite and gallium phosphate in the temperature range 8-300 K

Abstract

The temperature dependence of the optical‐phonon wavenumbers and bandwidths in the isomorphous α‐quartz, berlinite (AlPO4) and gallium phosphate (GaPO4) was investigated by Raman scattering experiments in the temperature range 8–300 K. Combining these data with those from high‐pressure Raman scattering experiments (up to 20 GPa), we estimated the implicit (thermal volume expansion) and explicit (pure self‐anharmonic) temperature contribution to the temperature wavenumber shifts observed in isobaric experiments. In the framework of the Grüneisen approximation, the mode‐Grüneisen parameters of the A1 modes in GaPO4 are given. As expected, these results are similar to those previously reported for quartz and berlinite. In the temperature range 8–300 K, which is less than the α–β temperature of transition (Tα → β ≈ 850 K) of quartz and berlinite, the phonon population decay processes appear to be the main cause of phonon damping in the three materials. Copyright © 2000 John Wiley & Sons, Ltd.

Anharmonic line shift and linewidth of the Raman modes in TlInS2 layered crystals

“…Similar anomalous behavior with a slight increase in wavenumbers has been observed for the Raman-active modes at 146.3 and 1060 cm 1 in GaPO 4 and 1112 cm 1 in AlPO 4 chain crystals. 22 Such dependences have been reported also for two infrared-active TO lines (364 and 495 cm 1 ) in˛-quartz and connected with a weak hardening of these phonons with volume expansion. 23 The anisotropic elastic properties of the solids may be the cause of such effects, as suggested by Sherman considering the case of anisotropic Se and Te crystals.…”

Quartz-bearing C–O–H fluid inclusions diamond: Retracing the pressure–temperature path in the mantle using calibrated high temperature IR spectroscopy

“…The frequency of the E mode (800.6 cm À1 at ambient pressure and temperature) shows a strong negative temperature dependence that remains approximately constant throughout the range studied here (Gervais and Piriou, 1975). We can attempt to ''correct'' the pressure obtained from the room temperature calibration by applying Dm 810 (cm À1 ) = À0.023 AE T, that is valid over the range 226 temperature 6512°C (Gervais and Piriou, 1975); the data of Ouillon et al (2000) was used to correct for temperature <22°C. This approach resulted in revised quartz E-mode of 831.9 cm À1 at temperature = 737°C (Fig.…”

“…The Mbuji-Mayi kimberlite cluster from which the present diamond sample was obtained is located on the $2.7 Ga Kasai craton (e.g., Demaiffe et al, 1991) in south- Gervais and Piriou (1975) and Ouillon et al (2000), and A 2 -mode (black squares). (b) Pressure calculated from the uncorrected E-mode (black diamonds) which gives a ''low'' internal pressure, from the temperature corrected E-mode (open diamonds), which gives a ''high'' pressure, and from the A 2 -mode (black squares); the position of the A 2 mode could not be determined above 300°C.…”

Ultrastable phonon frequencies in α -quartz-type BPO4 at high temperature

“…Phonon frequencies in normal solids shift to lower values at high temperature due to phonon anharmonicity [6][7][8][9][10] . Explicit contributions (phonon-phonon interactions or Umklapp term) correspond to increased amplitude of vibration at high temperature.…”

“…The phonon wavenumber shift due to the latter implicit contribution of a given mode can be expressed as a function of the unit cell volume introducing the quasi-harmonic mode Grüneisen parameter as follows 10 :…”