Effect of transformation twins on the anelastic behavior of polycrystalline Ca1−xSrxTiO3 and SrxBa1−xSnO3 perovskite in relation to the seismic properties of Earth's mantle perovskite
✍ Scribed by M. Daraktchiev; R.J. Harrison; E.H. Mountstevens; S.A.T. Redfern
- Publisher
- Elsevier Science
- Year
- 2006
- Tongue
- English
- Weight
- 206 KB
- Volume
- 442
- Category
- Article
- ISSN
- 0921-5093
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✦ Synopsis
The mechanical loss of Ca 1-x Sr x TiO 3 as a function of temperature has been studied up to 1000 • C using dynamical mechanical analysis. The loss spectrum reveals a relaxation peak in the tetragonal phase and negligible mechanical loss in the cubic and orthorhombic phases. The peak is accompanied by a softening of the storage modulus, caused by the formation of mobile transformation twin domain walls. The small value of internal friction in the orthorhombic phase is associated with a negative volume strain, resulting in domain walls that are strongly pinned by lattice defects. The volume changes and mechanical loss in Ca 1-x Sr x TiO 3 are compared with those in Sr x Ba 1-x SnO 3 , a system which shows a positive volume strain. In contrast to Ca 1-x Sr x TiO 3 , Sr x Ba 1-x SnO 3 displays a thermally activated peak in the orthorhombic phase. A frequency-independent peak attributed to the tetragonal-orthorhombic transition is also seen. The positive volume strain in Sr x Ba 1-x SnO 3 results in domain wall structures that are less strongly pinned by lattice defects.