P. Zinn et al., KINETIC-STUDIES OF THE CRYSTALLIZATION OF COESITE USING SYNCHROTRON-RADIATION, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 97(1-4), 1995, pp. 89-91
For energy-dispersive X-ray powder diffraction under high pressure and
high temperature a multi-anvil-X-ray apparatus (MAX 80) has been inst
alled at HASYLAB. This instrument allows to measure diffraction data a
t very short intervals and thus study time dependent phenomena. As an
example we have investigated the kinetics of the alpha-quartz-coesite
phase transformation. The kinetics was determined by in situ experimen
ts between temperatures of 870 and 1170 K and in a pressure range of 3
0-50 kbar. The structural changes were directly imaged using synchrotr
on radiation. The experimental results yield the rate constant K-c for
the growth of coesite from quartz as a starting material under dry co
nditions. For the transition three K-c values from 6.0 X 10(4) to 2.2
X 10(4) s(-1) for different p/t-ranges were determined.