EFFECT OF A TWO-DIMENSIONAL PRESSURE ON THE CURIE POINT OF BARIUM TITANATE
Abstract
By hydraulics, a single crystal of BaTiO3 in the shape of a flat circular disk was subjected to a pressure exerted on the edges. After removal of all domains that were not normal to the disk by a slight pressure, the stress system consisted of equal pressures on the 2 a axes and none on the c axis. The transition temperature increased with the square of the 2-dimensional and hydrostatic stress systems was obtained by using Devonshire's expansion for energy (phil. Mag. 40:1040, 1949;42:1065, 1951) and the appropriate Legendre transformation. The expansion had to be supplemented to obtain a quadratic effect. The evaluation of the effect of pressure on the transition temperature was difficult when higher terms were included, but the effect on Curie-Weiss temperature was easily determined. The laminar part of the Curie-Weiss temperature shift depended only on the lower terms in the free energy expansion; it provided 2 independent relations for determining the 2 g coefficients. The quadraulic shift of the Curie-Weiss temperature depended on the higher terms with which the Devonshire's exspansion was suupplemented, and an interpretation of these higher terms gave an upward direction to the shift.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1953
- Accession Number
- AD0019933
Entities
People
- P. W. Forsbergh Jr.
Organizations
- Massachusetts Institute of Technology