A Critical Force Constant of the Structural Phase Transition in Quartz
نویسندگان
چکیده
Long wavelength optical phonons of quartz were analyzed by a Born-Von Karman model not previously used. It was found that only one force constant associated with the turning of the Si-0 bonds has a critical effect on the softmode frequency and the a-p transition in quartz. The square of the soft-mode frequency was found to depend linearly on this force constant which has the temperature dependence K(T) = -5.33 + 225.3 X 10~(851-7*) in units of 10 dyn/cm.
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