Solid‐State Chemistry and Non‐Linear Properties of Tetragonal Tungsten Bronzes Materials

Simon, A.; Ravez, J.

doi:10.1002/chin.200735227

Cited by 17 publications

(23 citation statements)

References 33 publications

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“…16 The simplest ferroelectric TTB is tetragonal with similar cell dimensions to the aristotype structure but with non-centrosymmetric symmetry, point group 4mm, with P4bm the most commonly assigned space group. 17 However, orthorhombic distortions of the structure are common, typically resulting in larger supercells. The simplest such orthorhombic superstructure requires a ca.…”

Section: Introductionmentioning

confidence: 99%

Relaxor-to-Ferroelectric Crossover and Disruption of Polar Order in “Empty” Tetragonal Tungsten Bronzes

Gardner

Tang

et al. 2016

Chem. Mater.

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Combined temperature-dependent structural and electrical characterization of a series of "empty" ferroelectric tetragonal tungsten bronzes (TTBs) of composition Ba 4 (La 1-x Nd x ) 0.67 ! 1.33 Nb 10 O 30 are reported. The La-material exhibits a temperature dependent crossover from relaxor-ferroelectric to polar (but non-ferroelectric) to linear dielectric behavior. The loss of ferroelectric switching in the polar, non-ferroelectric phase is accompanied by disorder associated with structural relaxation due the significant vacancy concentration at the A1-perovskite-like site. In this disordered regime, large polarization can be re-established with application of sufficient electric field, however relaxation back into the disordered phase occurs on removal of the field as indicated by the loss of remenant polarization. The field against which "backswitching" (depolarization) occurs increases with temperature indicating increasing stability of the disordered regime. The disordered phase can be de-stabilized by substituting Nd for La at the A1-site and which reintroduces "normal" ferroelectric behavior. IntroductionThe field of polar dielectrics (piezo-, pyro-and ferro-electrics) is dominated by oxides with the perovskite structure.1, 2 The role of compositional tuning of perovskites and structural

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Section: Introductionmentioning

confidence: 99%

Relaxor-to-Ferroelectric Crossover and Disruption of Polar Order in “Empty” Tetragonal Tungsten Bronzes

Gardner

Tang

et al. 2016

Chem. Mater.

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“…TTB structure has the general formula of A 2 BC 2 M 5 X 15 , where X = O is anion, M = Ta is octahedral cation, and A, B and C are cations. A, B and C correspond to cationic sites with 15, 12 and 9 CN (coordination number), respectively [19]. TTB-BaTa 2 O 6 structure has the pentagonal (A) sites and the square (B) sites which are occupied or not occupied by Ba 2+ cations, while small triangular (C) sites have vacancies.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Optical Characterization of Red-Emitting BaTa2O6:Eu3+ Phosphors

et al. 2016

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Undoped and Eu(3+) doped BaTa2O6 phosphors were synthesized via solid state reaction method and characterized by using XRD, SEM-EDS and photoluminescence (PL) analyses. The XRD results revealed that the crystal structure of BaTa2O6 allowed up to 10 mol% levels of Eu(3+) ions due to the TTB characteristic network of adjacent octahedrals. SEM-EDS analyses confirmed the formation of BaTa2O6 structure and EuTaO4 secondary phase. BaTa2O6:Eu(3+) phosphors exhibited orange and red emissions at 592.2 nm and 615.7 nm in the visible region respectively. The Commission Internationale d'Eclairage (CIE) chromaticity coordinates of the BaTa2O6:Eu(3+) phosphors that excited at λ ex = 400 nm ranged from orangish-red to pinkish-red depending on increasing Eu(3+) concentration.

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“…The A1 sites are 12-coordinated and defined by 8 octahedra, the four larger A2 sites are 15-coordinated and defined by 10 octahedra, while the four trigonal C-sites are 9-coordinated and defined by 6 octahedra; moreover, the BO 6 octahedra are non-equivalent (two B1 sites and eight B2 sites) - Figure 1. This rich diversity of elements which can be incorporated into the TTB structure allows for compositional tuning that has been exploited for development of new phases [13,19] ranging from ferroelectrics [20][21][22] to microwave dielectrics [23,24] and to ionic conductors [25]. During the last few years, the research dedicated to novel TTB ferroelectric and ferroelectric-related materials resurrected [15][16][17][18][19][20][21][22][26][27][28][29][30][31], with the Ba 6 FeNb 9 O 30 (BFNO) [32][33][34][35] as starting point.…”

Section: Introductionmentioning

confidence: 99%

“…This rich diversity of elements which can be incorporated into the TTB structure allows for compositional tuning that has been exploited for development of new phases [13,19] ranging from ferroelectrics [20][21][22] to microwave dielectrics [23,24] and to ionic conductors [25]. During the last few years, the research dedicated to novel TTB ferroelectric and ferroelectric-related materials resurrected [15][16][17][18][19][20][21][22][26][27][28][29][30][31], with the Ba 6 FeNb 9 O 30 (BFNO) [32][33][34][35] as starting point. Earlier data reported that BFNO is ferroelectric with T C values either in the range 133-138 K [36] or 570-583 K [37,38], however being not electrically homogeneous [29] and with oxygen vacancy gradients due to the variable oxidation state of Fe (Fe 3+ /Fe 2+ ); both low temperature dielectric spectroscopy and high temperature impedance spectroscopy measurements indicated more electroactive regions than anticipated [16].…”

Section: Introductionmentioning

confidence: 99%

Microstructural and high-temperature impedance spectroscopy study of Ba6MNb9O30 (M=Ga, Sc, In) relaxor dielectric ceramics with tetragonal tungsten bronze structure

Rotaru

Morrison

2016

Ceramics International

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Cite this article as: Andrei. Rotaru and Finlay D. Morrison, Microstructural and high-temperature impedance spectroscopy study of Ba 6 MNb 9 O 30 (M=Ga, Sc, In) relaxor dielectric ceramics with tetragonal tungsten bronze structure, Ceramics International, http://dx.doi.org/10. 1016/j.ceramint.2016.04.102 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. poorer microstructure, with many small and poorly-bonded grains gathered in agglomerates, resulting in significant continuous porosity and poorly defined grain boundary regions. The electroactive regions were characterised by the bulk and grain boundaries capacitances and resistances, while their contribution to the electrical conduction process was estimated by determining activation energies from the temperature (Arrhenius) dependence of both electric conductivities and time constants. For Ga and In analogues the electronic conductivity are dominated by the bulk response, while for Sc analogue, the poorly defined grain boundariesgive a bulk-like response, mixing with the main bulk contribution.

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Solid‐State Chemistry and Non‐Linear Properties of Tetragonal Tungsten Bronzes Materials

Abstract: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Cited by 17 publications

References 33 publications

Relaxor-to-Ferroelectric Crossover and Disruption of Polar Order in “Empty” Tetragonal Tungsten Bronzes

Relaxor-to-Ferroelectric Crossover and Disruption of Polar Order in “Empty” Tetragonal Tungsten Bronzes

Synthesis and Optical Characterization of Red-Emitting BaTa2O6:Eu3+ Phosphors

Microstructural and high-temperature impedance spectroscopy study of Ba6MNb9O30 (M=Ga, Sc, In) relaxor dielectric ceramics with tetragonal tungsten bronze structure

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