Compact high-temperature cell for Brillouin scattering measurements

Abstract

A compact ceramic high-temperature cell for Brillouin spectroscopy was designed and tested. The cell can be mounted onto a three-or four-circle goniometer and allows collection of the full set of elastic constants of minerals to temperatures in excess of 1500 K from samples with dimensions of 100ϫ100ϫ20 m or smaller. As a test of the instrument the single-crystal elastic constants of MgO were measured to 1510͑10͒ K, and are found to be in excellent agreement with earlier independent results. The high-temperature cell should be useful for other types of spectroscopic measurements, and is especially useful in situations where spectral properties vary with the scattering geometry.

High temperature elasticity measurements on oxides by Brillouin spectroscopy with resistive and IR laser heating

“…8 and listed in Table 1, along with the previous ultrasonic results of Sumino et al 30 and Isaak et al 29 Our Brillouin results are in agreement with previous measurements, and no systematic deviations from the trend of the ultrasonic results were observed. Further descriptions of these results are given by Sinogeikin et al 22 The excellent agreement between our results and independent measurements at lower temperatures demonstrates that our experimental techniques can be used to obtain accurate high-temperature single-crystal elasticity measurements on very small crystals to temperatures in excess of 1500 K.…”

“…22 Up to the maximum temperature the Brillouin spectra were of superb quality with negligible thermal background ( Fig. 6).…”

“…3 and 4) to temperatures in excess of 1500 K. 22 The cell is compact (about 5 cm in maximum dimension), and easily fits onto a standard three-or four-circle goniometer, allowing a number of additional applications such as X-ray scattering. Because the cell mounts on a goniometer, one obtains very good control of the scattering geometry, and any phonon direction within a plane of the platelet can be easily sampled by changing the χ-angle of the goniometer.…”

“…5 in Ref. 22). In later experiments we used 250 m thick platinum foil as a sample holder to provide thermal mass.…”

“…Finally, the cell is easily used with very small samples (e.g., 100 × 100 × 20 m or smaller). [23][24][25] The main body of the original cell can be constructed from a machinable alumina silicate ceramic 22 or metal (Inconel) depending on temperature requirements. A metal cell pro- vides better mechanical stability and is easier to handle, but the high thermal conductivity of the metal body limits the maximum temperature to about 1300-1400 K if a Pt-Rh heating element is used.…”