COMPARISON OF THE PRESSURE-INDUCED FREQUENCY-SHIFT OF SM-YAG TO THE RUBY AND NITROGEN VIBRON PRESSURE SCALES FROM 6-K TO 820-K AND 0 TO 25 GPA AND SUGGESTIONS FOR USE AS A HIGH-TEMPERATURE PRESSURE CALIBRANT

The pressure-induced frequency shift of the Sm:YAG Y1 peak at elevated temperature is calibrated against the temperature-corrected Raman shift of the nitrogen vibron and, at temperatures less than 673 K, the R1 shift of ruby. The results presented here indicate that pressure can be determined from the Y1 and Y2 peak frequencies, without temperature correction, from 6 to 820 K and from 1 bar to 25 GPa by using the equations: P(GPa) = -0.12204 (omega(obs)Y1 -16187.2) and P(GPa) = -0.15188 omega(obs)Y2 -16232.2). However, pressure determinations based on Y2 are less accurate, especially at high temperature. At elevated temperature, the Sm:YAG Y1 and Y2 peak frequencies are most accurately determined by curve fitting a spectral window at least 400 cm-1 wide. The spectral range was chosen in order to include the decay of the intensity of the Lorentzian Y1 peak to a background value and incorporate a third peak at 16360 cm-1.