ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
By using a thin 13C diamond chip together with a 12C diamond chip as sensors, the diamond Raman spectra provide the means to measure pressure precisely (±0.3 GPa) at any temperature (10–1200 K) and simultaneous hydrostatic (or quasihydrostatic) pressure (0–25 GPa) for any sample compatible with an externally heated diamond-anvil cell. Minimum interference between the Raman spectrum from the diamond anvils and those of the pressure sensors is obtained by measuring pressures with the Raman signal from the 13C diamond chip up to 13 GPa, and that from the12C chip above 10 GPa. The best crystallographic orientation of the diamond anvils is with the [100] direction along the direction of applied force, in order to further minimize the interference. At 298 K, the pressure dependence of the 13C diamond first-order Raman line is given byν(P)=νRT+aP for 91 at. % 13C diamond, whereνRT(13C)=1287.79±0.28 cm−1 anda(13C)=2.83±0.05 cm−1/GPa. Analysis of values from the literature shows that the pressure dependence of the Raman line of 12C diamond is best described by the parametersνRT(12C)=1332.5 cm−1 anda(12C)=2.90±0.05 cm−1/GPa. The temperature dependence of the diamond Raman line is best described by ν(T)−νRT=b0 for T≤200 K, andν(T)−νRT=b0+b1.5Tk1.5 for200 K≤T≤1500 K, where Tk=T−200 K. For 91 at. %13C diamond, the parameters are b0=0.450±0.025 cm−1;b1.5=−(7.36±0.09)×10−4 cm−1 K−1.5; and for 12C diamond, the parameters areb0=0.467±0.033 cm−1,b1.5=−(7.56±0.10)×10−4 cm−1 K−1.5. Although no quantitative theoretical models are available for calculating the Raman shift as a function of temperature, the excellent fits to the data suggest that theTk1.5 dependence above has a physical basis. © 1997 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.366268
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