Measurements of the spontaneous polarization in KH(2)PO(2)
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Authors
Benepe, John Wesley
Subjects
Ferroelectricity
Potassium Dihydrogen Phosphate (KH(2)PO(4))
Spontaneous polarization
Electrocaloric effect
Specific heat
Critical point phenomena
Phase transition
Potassium Dihydrogen Phosphate (KH(2)PO(4))
Spontaneous polarization
Electrocaloric effect
Specific heat
Critical point phenomena
Phase transition
Advisors
Reese, W.
Date of Issue
1970-12
Date
December 1970
Publisher
Monterey, California; Naval Postgraduate School
Language
en_US
Abstract
Measurements of the spontaneous polarization of KH(2)PO(4) within 1 K if the ferroelectric transition are reported. the measurement employed the electrocaloric effect, allowing simultaneous determination of the polarization and its temperature derivative. The derivative computed from polarization measurements compares well with direct determinations of (OP/OT)e, demonstrating thermodynamic consistency of the measurements. The transition is first order with a discontinuous jump in the polarization of 1.87 uc/cm(2) at the transition. Laudau theory allows separate calculation at specific heat contributions of the lattice and polarization and thus the total specific heat, which agrees very well with direct calorimetric determinations, although the decomposition differs from that previously assumed. This indicates that Landau theory provides a good description of the transition in KH(2)PO(4) and that there is a calorimetric anomaly not directly associated with the polarization. The free energy expansion best fitting the data contains P(4) and P(8) terms and no P(6) term.
Type
Thesis
Description
Series/Report No
Department
Department of Physics
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.