Extension of the Lifshitz-point concept to first-order phase transitions: Incommensurate NaNO/sub 2/ in a transverse electric field
The theory of the Lifshitz point, a triple point in the phase diagram of systems with incommensurate phases, is extended to systems in which the direct para-ferro transition is first order. The structure of the phase diagram is shown to be considerably more complex than in the usual case of a second-order direct transition. There is a virtual Lifshitz point at which the T/sub I/ and T/sub 0/ phase-transition lines cross, but it is not a triple point. A new tricritical point is found at which the para-to-incommensurate transition changes from second to first order, and a new triple point is found, distinct from the virtual Lifshitz point. We present the results of an elastic neutron scattering study of the incommensurate ferroelectric NaNO/sub 2/ in transverse electric fields which exhibits behavior resembling that found in the theoretical analysis. We therefore extrapolate the experimental phase diagrams to construct a plausible picture of the region of the virtual Lifshitz point in NaNO/sub 2/.
- Research Organization:
- Department of Physics, City College, City University of New York, New York 10031
- OSTI ID:
- 7006847
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Vol. 34:11
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NITRITES
PHASE DIAGRAMS
SODIUM COMPOUNDS
CRITICAL TEMPERATURE
FERROELECTRIC MATERIALS
FREE ENERGY
MEAN-FIELD THEORY
NEUTRON DIFFRACTION
PHASE TRANSFORMATIONS
ALKALI METAL COMPOUNDS
COHERENT SCATTERING
DIAGRAMS
DIFFRACTION
ENERGY
NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SCATTERING
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
360602* - Other Materials- Structure & Phase Studies