Wa. Bassett et al., A NEW DIAMOND-ANVIL CELL FOR HYDROTHERMAL STUDIES TO 2.5 GPA AND FROM- 190-DEGREES-C TO 1200-DEGREES-C, Review of scientific instruments, 64(8), 1993, pp. 2340-2345
A new style of diamond anvil cell (DAC) has been designed and built fo
r conducting research in fluids at pressures to 2.5 GPa and temperatur
es from -190 to 1200-degrees-C. The new DAC has been used for optical
microscope observations and synchrotron x-ray diffraction studies. Fri
nges produced by interference of laser light reflected from top and bo
ttom anvil faces and from top and bottom sample faces provide a very s
ensitive means of monitoring the volume of sample chamber and for obse
rving volume and refractive index changes in samples that have resulte
d from transitions and reactions. X-ray diffraction patterns of sample
s under hydrothermal conditions have been made by the energy dispersiv
e method using synchrotron radiation. The new DAC has individual heate
rs and individual thermocouples for the upper and lower anvils that ca
n be controlled and can maintain temperatures with an accuracy of +/-
0.5-degrees-C. Low temperatures are achieved by introducing liquid nit
rogen directly into the DAC. The equation of state of H2O and the alph
a-beta quartz transition are used to determine pressure with an accura
cy of +/- 1 % in the aqueous samples. The new DAC has been used to red
etermine five isochores of H2O as well as the dehydration curves of br
ucite, Mg(OH)2, and muscovite, KAl2(Si3Al)O10(OH)2.