A-site size effect in a family of unfilled ferroelectric tetragonal tungsten bronzes: Ba4R0.67Nb10O30 (R = La, Nd, Sm, Gd, Dy and Y)

Jonathan Gardner; Finlay D. Morrison

doi:10.1039/c4dt00126e

A-site size effect in a family of unfilled ferroelectric tetragonal tungsten bronzes: Ba₄R_0.67Nb₁₀O₃₀ (R = La, Nd, Sm, Gd, Dy and Y)

Jonathan Gardner, Finlay D. Morrison^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

The effect of A-cation size on the structural and electrical properties in a family of ferroelectric tetragonal tungsten bronzes (TTBs) Ba₄R_0.67□_1.33Nb₁₀O₃₀ (R = La, Nd, Sm, Gd, Dy and Y; □ = vacancy) was investigated. In each case, the crystal structure, as determined from lab-based ambient powder X-ray diffraction (PXRD), is metrically tetragonal and can be refined in the P4bm space group. XRD data show an increased splitting of hk0 00l reflections with decreasing R cation size indicating an increasing tetragonal distortion (measured by tetragonality c/a). Dielectric data and ferroelectric measurements indicate that the ferroelectric Curie temperature, T_C, increases with decreasing R size and so a direct correlation between T_Cand tetragonality/ionic radius of R is demonstrated. Rietveld refinements show that the large A2-site is fully occupied by Ba²⁺ and, in addition to the R cation size, the presence of vacancies at the A1-site (perovskite-like site) is also shown to strongly affect the stability of ferroelectricity in this structure type.

Original language	English
Pages (from-to)	11687-11695
Number of pages	9
Journal	Dalton Transactions
Volume	43
Issue number	30
Early online date	13 Jun 2014
DOIs	https://doi.org/10.1039/c4dt00126e
Publication status	Published - 14 Aug 2014

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Finlay Morrison
- fm40st-andrews.acuk
- School of Chemistry - Professor
- EaSTCHEM
Person: Academic

Data underpinning - Relaxor-to-ferroelectric crossover and disruption of polar order in ‘empty’ tetragonal tungsten bronzes
Gardner, J. (Creator), Yu, F. (Creator), Tang, C. (Contributor), Kockelmann, W. (Contributor), Zhou, W. (Creator) & Morrison, F. D. (Creator), University of St Andrews, 8 Jun 2016
DOI: 10.17630/a7a9bc13-b5cb-485d-914a-923832f25190
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title = "A-site size effect in a family of unfilled ferroelectric tetragonal tungsten bronzes: Ba4R0.67Nb10O30 (R = La, Nd, Sm, Gd, Dy and Y)",

abstract = "The effect of A-cation size on the structural and electrical properties in a family of ferroelectric tetragonal tungsten bronzes (TTBs) Ba4R0.67□1.33Nb10O30 (R = La, Nd, Sm, Gd, Dy and Y; □ = vacancy) was investigated. In each case, the crystal structure, as determined from lab-based ambient powder X-ray diffraction (PXRD), is metrically tetragonal and can be refined in the P4bm space group. XRD data show an increased splitting of hk0 00l reflections with decreasing R cation size indicating an increasing tetragonal distortion (measured by tetragonality c/a). Dielectric data and ferroelectric measurements indicate that the ferroelectric Curie temperature, TC, increases with decreasing R size and so a direct correlation between TC and tetragonality/ionic radius of R is demonstrated. Rietveld refinements show that the large A2-site is fully occupied by Ba2+ and, in addition to the R cation size, the presence of vacancies at the A1-site (perovskite-like site) is also shown to strongly affect the stability of ferroelectricity in this structure type.",

author = "Jonathan Gardner and Morrison, {Finlay D.}",

note = "JG acknowledges the EPSRC and EaStCHEM for provision of a studentship via the doctoral training grant.",

year = "2014",

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doi = "10.1039/c4dt00126e",

language = "English",

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TY - JOUR

T1 - A-site size effect in a family of unfilled ferroelectric tetragonal tungsten bronzes

T2 - Ba4R0.67Nb10O30 (R = La, Nd, Sm, Gd, Dy and Y)

AU - Gardner, Jonathan

AU - Morrison, Finlay D.

N1 - JG acknowledges the EPSRC and EaStCHEM for provision of a studentship via the doctoral training grant.

PY - 2014/8/14

Y1 - 2014/8/14

N2 - The effect of A-cation size on the structural and electrical properties in a family of ferroelectric tetragonal tungsten bronzes (TTBs) Ba4R0.67□1.33Nb10O30 (R = La, Nd, Sm, Gd, Dy and Y; □ = vacancy) was investigated. In each case, the crystal structure, as determined from lab-based ambient powder X-ray diffraction (PXRD), is metrically tetragonal and can be refined in the P4bm space group. XRD data show an increased splitting of hk0 00l reflections with decreasing R cation size indicating an increasing tetragonal distortion (measured by tetragonality c/a). Dielectric data and ferroelectric measurements indicate that the ferroelectric Curie temperature, TC, increases with decreasing R size and so a direct correlation between TC and tetragonality/ionic radius of R is demonstrated. Rietveld refinements show that the large A2-site is fully occupied by Ba2+ and, in addition to the R cation size, the presence of vacancies at the A1-site (perovskite-like site) is also shown to strongly affect the stability of ferroelectricity in this structure type.

AB - The effect of A-cation size on the structural and electrical properties in a family of ferroelectric tetragonal tungsten bronzes (TTBs) Ba4R0.67□1.33Nb10O30 (R = La, Nd, Sm, Gd, Dy and Y; □ = vacancy) was investigated. In each case, the crystal structure, as determined from lab-based ambient powder X-ray diffraction (PXRD), is metrically tetragonal and can be refined in the P4bm space group. XRD data show an increased splitting of hk0 00l reflections with decreasing R cation size indicating an increasing tetragonal distortion (measured by tetragonality c/a). Dielectric data and ferroelectric measurements indicate that the ferroelectric Curie temperature, TC, increases with decreasing R size and so a direct correlation between TC and tetragonality/ionic radius of R is demonstrated. Rietveld refinements show that the large A2-site is fully occupied by Ba2+ and, in addition to the R cation size, the presence of vacancies at the A1-site (perovskite-like site) is also shown to strongly affect the stability of ferroelectricity in this structure type.

U2 - 10.1039/c4dt00126e

DO - 10.1039/c4dt00126e

M3 - Article

SN - 1477-9226

VL - 43

SP - 11687

EP - 11695

JO - Dalton Transactions

JF - Dalton Transactions

IS - 30

ER -

A-site size effect in a family of unfilled ferroelectric tetragonal tungsten bronzes: Ba4R0.67Nb10O30 (R = La, Nd, Sm, Gd, Dy and Y)

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Data underpinning - Relaxor-to-ferroelectric crossover and disruption of polar order in ‘empty’ tetragonal tungsten bronzes

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A-site size effect in a family of unfilled ferroelectric tetragonal tungsten bronzes: Ba₄R_0.67Nb₁₀O₃₀ (R = La, Nd, Sm, Gd, Dy and Y)