Elastic behaviour associated with the hierarchy of tilting transitions in SrZrO(3) has been examined using resonant ultrasound spectroscopy on a ceramic sample at temperatures between 153 and 1531 K. Changes in slope of the evolution of resonance frequencies with temperature indicate that phase transitions occur at 1038 K ([Formula: see text]), 1122 K ([Formula: see text]), and 1367 K ([Formula: see text]). Strain analysis of previously recorded neutron diffraction data shows that the [Formula: see text] and [Formula: see text] transitions are close to tricritical in character, and that [Formula: see text] is first order. Deviations from the form of the elastic behaviour predicted by Landau theory are found. In particular, elastic softening in the vicinity of the [Formula: see text] transition suggests that local dynamical fluctuations between individual tilt systems occur, rather than a discontinuous switch from one phase to another. Determinations of the mechanical quality factor, Q, show that SrZrO(3) in the [Formula: see text] phase is a classically high-Q (i.e. non-dissipating) cubic material. I4/mcm and Imma phases both have much greater dissipation (low Q), which is tentatively attributed to the mobility of twin walls. The room temperature Pnma phase is unexpectedly much stiffer than both I4/mcm and Imma phases and has high Q. It appears that when two separate tilt systems operate, as in Pnma, they can interact to reduce strain/order parameter relaxations.

The effects of grain size on the elastic properties of quartz through the α–β phase transition have been investigated by resonant ultrasound spectroscopy. It is found that there are three regimes, dependent on grain size, within which elastic properties show different evolutions with temperature. In the large grain size regime, as represented by a quartzite sample with ∼100–300 µm grains, microcracking is believed to occur in the vicinity of the transition point, allowing grains to pull apart. In the intermediate grain size regime, as represented by novaculite (1–5 µm grain size) and Ethiebeaton agate (∼120 nm grain size), bulk and shear moduli through the transition follow closely the values expected from averages of single crystal data. The novaculite sample, however, has a transition temperature ∼7 °C higher than that of single crystal quartz. This is assumed to be due to the development of internal pressure arising from anisotropic thermal expansion. In the small grain size region, agates from Mexico (∼65 nm) and Brazil (∼50 nm) show significant reductions in the amount of softening of the bulk modulus as the transition point is approached from below. This is consistent with a tendency for the transition to become more second order in character. The apparent changes towards second order character do not match quantitative predictions for samples with homogeneous strain across elastically clamped nanocrystals, however. Some of the elastic variations are also due to the presence of moganite in these samples. True ‘nanobehaviour’ for quartz in ceramic samples thus appears to be restricted to grain sizes of less than ∼50 nm.

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The sequence of phase transitions due to octahedral tilting across the Sr(Zr,Ti)O 3 solid solution series has been investigated by resonant ultrasound spectroscopy at high and low temperatures using ceramic samples. The elastic behaviour associated with phase transitions as a function of composition in Sr(Zr,Ti)O 3 at room temperature is proposed to be analogous to that as a function of temperature in what is assumed to be I mma, appear to have stability fields across the full compositional range and both show large dissipation effects, most probably due to twin wall mobility. In contrast, the Zr-rich Pnma phase, which should contain transformation twin walls, is an unexpectedly stiff and non-dissipating material, similar to the high temperature and/or Ti-rich Pm3m phase. In the case of Pnma, this is attributed to coupling between the two order parameters, which could impede relaxation responses to an applied stress. The Pm3m structure is a classically stiff cubic perovskite and no transformation-related dissipation processes are expected.

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