## Abstract

A thermodynamic theory is presented to model the phase transitions and properties of lead zirconate. The free energy ΔG is expressed as a power series in terms of the ferroelectric polarization (P_{i}=P _{a}i+P_{b}i) and antiferroelectric polarization (p _{i}=P_{a}i-P_{b}i) including all possible terms up to the sixth power, but only first-order cross coupling terms and couplings to elastic stress. Under the assumption that only the lowest-order coefficients of P_{i} and p_{i} are linearly temperature dependent (Curie-Weiss behavior) and all other constants are temperature independent, experimental data are used to define the constants and permit calculation of ferroelectric and antiferroelectric free energies as a function of temperature. Use of the function to define the averaged dielectric permittivity at room temperature in the antiferroelectric phase gives a value of ε_{R}=120 in good agreement with recent microwave measurements. A simplified technique for modifying the function to explore solid solution with lead titanate is examined, and shown to lead to excellent agreement with the known phase diagram.

Original language | English (US) |
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Pages (from-to) | 3173-3180 |

Number of pages | 8 |

Journal | Journal of Applied Physics |

Volume | 65 |

Issue number | 8 |

DOIs | |

State | Published - Dec 1 1989 |

## All Science Journal Classification (ASJC) codes

- Physics and Astronomy(all)