Strain glass in ferroelastic systems: Premartensitic tweed versus strain glass

Abstract

Cluster-spin glass and ferroelectric relaxors have been observed in defectcontaining ferromagnetic systems and ferroelectric systems, respectively. However, it is unclear whether or not an analogous glass state exists in the physically parallel ferroelastic (or martensitic) systems. In the 1990s, theoretical studies suggested that premartensitic tweed could be viewed as a strain glass. However, there has been no experimental verification of this hypothesis. In this paper, we provide an experimental test of this hypothesis by measuring the possible glass signatures in two well-known premartensitic tweed systems prior to their martensitic transformation: one Ni 63 Al 37 and the other Ti 50 Ni 47 Fe 3 martensitic alloy. Our experiments show that no glass signatures exist for the premartensitic tweed in both systems. There is no mechanical susceptibility/modulus anomaly in the tweed temperature regime, suggesting no glass transition exists. The tweed remains ergodic, inconsistent with a frozen glass. These two critical experiments show that premartensitic tweed is not a frozen glass state. We demonstrate that strain glass exists in ferroelastic/martensitic systems but only in defect-containing ferroelastic/martensitic systems with defect concentration exceeding a critical value. This strain glass is a mechanical analogue of cluster-spin glass or ferroelectric relaxors, and possesses all the features of a glass. We further show that the tweed is equivalent to an 'unfrozen state' of a strain glass. Finally, we demonstrate that the microscopic origin of the strain glass can be easily understood in analogy with the behavior of a 'defect-containing domino array'.

Observation of partially incoherent ⟨110⟩ boundaries between polar nanodomains in Na1/2Bi1/2TiO3 single crystals

“…The well-defined orientation relation between the nanodomains is typical of that formed to relax the elastic energy of an invariant plane strain. 28,29 However, some areas of the nanodomain boundaries oriented along the ͗110͘ consisted of planar defects. In order to better observe these features of the nanodomain structure, the lattice image was digitally filtered by selecting all the spots excluding the central spot in FFT using 1.5 nm −1 smooth edge masks and then taken inverse Fourier transformation which is presented in Fig.…”

“…Tweedlike structures are typically found in systems containing nanodomains which have local T lattice structures with a relatively high c/a ratio, such as for example premartensitic 27 and/or strain glass states. 28,29 This observation is perplexing for NBT, as the structure is R ͑a r = 3.96 Å͒ with only a small R angle ͑␣ r = 89.9°͒. 16 To learn more about the polar nanodomains, we performed HRTEM studies.…”

Diverging Relaxation Times of Domain Wall Motion Indicating Glassy Dynamics in Ferroelastics

“…1-5 nm size, which grow with decreasing temperature and get frozen at about 20-25 nm below T g . Ren et al 35 explained the observed strain glass behavior as a defect induced suppression of long range order, leading to the appearance of dynamic nanodomains whose dynamics freeze at T g . Recently it was argued 18 that in the case of ferroelastic materials domain boundary patterns can evolve glasslike states while the underlying matrix remains fully crystalline, without any defect induced disorder.…”

Recent progresses in the understanding of the elastic and anelastic properties of H-free, H-doped and H-contaminated NiTi based alloys

“…As anticipated in a preceding subsection these authors attributed the modulus dip and the IF peak to a local strain glass transition, which was subsequently further investigated by X-rays, electron microscopy, zero-field cooling/field cooling and static stress-strain experiments (Refs. [24][25][26][27][28][29][30][31]35). Their X-ray diffraction patterns are shown in figure 18(a) while the IF and the Young's modulus results (Refs.…”