Dynamics of ferroelastic domains in crystals and ceramics
Mechanical Spectroscopy
For the first time, we have carried out a full measurement of a model system (LaAlO3) as a function of applied force, frequency, and temperature. This allows us to determine the real (J1) and imaginary (J2) components of the elastic compliance in ln(frequency) - 1/T space:
Horizontal or vertical trajectories across this plane allows a Cole-Cole type analysis of the relaxation phenomenon:
The relaxation is neither Arrhenius nor Vogel Fulcher in character, but we are able to extract a temperature dependent variation in relaxation times (or equivalently in activation energies) for the domain movement. Different mechanical regimes are resolved in the force spectra, with crossover between regimes indicated by individual peaks in relaxation spectra. Overall the behaviour very well described by Cole-Cole equation with a parabolic temperature dependence of a distribution parameter. This indicates changing distribution of activation energies with temperature.
See R J Harrison, S A T Redfern, E K H Salje (2004) Dynamical excitation and anelastic relaxation of ferroelastic domain walls in LaAlO3. Phys Rev B, 69: 144101 for further details.
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