Grain growth kinetics and the effect of crystallographic anisotropy on normal grain growth of quartz |
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Authors: | Email author" target="_blank">Katsuyoshi?MichibayashiEmail author Hisashi?Imoto |
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Institution: | (1) Institute of Geosciences, Shizuoka University, Shizuoka 422-8529, Japan |
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Abstract: | Annealing experiments on agate were performed to investigate grain growth kinetics and the effect of crystallographic anisotropy
on normal grain growth of quartz. The experiments were conducted using a piston-cylinder apparatus at 700–800°C and 0.5 GPa
for 0–66 h. The grain growth rate was expressed by D
n
−D
0
n
= kt with k = k
0
exp(−H*/RT) where D
0
is the initial grain size at t = 0, with n = 4.4 ± 0.3, and H* = 191.3 ± 11.0 kJ/mol is the activation enthalpy and logk
0
= 19.8 ± 1.4. While the grain aspect ratios are nearly constant at ~0.7 (short/long) during grain growth, the longest axis
in individual grains tends to be oriented parallel to their c-axis, indicating that a primary crystal-preferred orientation of c-axis of the agate could result in the development of a weak shape-preferred orientation during grain growth. |
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Keywords: | |
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