Structural changes in Sr9In(PO4)7 during antiferroelectric phase transition

D.V. Deyneko; V.A. Morozov; S.Y. Stefanovich; A.A. Belik; B.I. Lazoryak; O.I. Lebedev

Structural changes in Sr9In(PO4)7 during antiferroelectric phase transition

D.V. Deyneko ¹ V.A. Morozov ¹ S.Y. Stefanovich ¹ A.A. Belik ² B.I. Lazoryak ¹ O.I. Lebedev ³

1 MSU - Lomonosov Moscow State University

2 WPI-MANA - International Center for Materials Nanoarchitectonics

3 CRISMAT - Laboratoire de cristallographie et sciences des matériaux

Abstract : Structural changes in Sr9In(PO4)7 during the antiferroelectric (AFE) phase transition are studied by X-ray powder diffraction, electron microscopy, second-harmonic-generation, and dielectric measurements. Sr9In(PO4)7 complements a group of Ca3(VO4)2-type ferroelectric (FE) phosphates and vanadates and is the first example of an AFE material in this family. Antiparallel shifts of Sr atoms from their average positions and ordering of the P1O4 tetrahedra form two contributions in the structural mechanism of the AFE phase transition a displacive contribution and an order-disorder constituent, respectively. The displacive and order-disorder type of structural changes may account for the obtained value of the Curie-Weiss constant (C ~ 104 K) which is in between the value usually observed for pure displacive (C ~ 105 K) and that for orderdisorder phase transitions (C ~ 103 K). The structural mechanism of the AFE phase transition in Sr9In(PO4)7 is very similar to that of the FE phase transition in Ca9R(PO4)7 and Ca9R(VO4)7. Both displacive and orderdisorder contributions are responsible for the physical properties of the Ca3(VO4)2-type materials. © 2016 Pleiades Publishing, Ltd.

Keywords : antiferroelectric phase transition electron microscopy indium phosphates strontium X-ray powder diffraction

Type de document :

Article dans une revue

Domaine :

Chimie

Chimie / Cristallographie

Chimie / Chimie théorique et/ou physique

Chimie / Matériaux

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https://hal-normandie-univ.archives-ouvertes.fr/hal-02184742
Contributeur : Université Normandie <>
Soumis le : mardi 16 juillet 2019 - 11:31:36
Dernière modification le : mercredi 4 septembre 2019 - 17:36:03

Structural changes in Sr9In(PO4)7 during antiferroelectric phase transition

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