Elastic and anelastic relaxations accompanying relaxor ferroelectric behaviour of Ba6GaNb9O30 tetragonal tungsten bronze from resonant ultrasound spectroscopy

Rotaru, Andrei; Schiemer, Jason; Carpenter, Michael A.

doi:10.1007/s10973-015-5202-z

Cited by 9 publications

(9 citation statements)

References 72 publications

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“…In the last few years, traditionally, niobates with tetragonal tungsten bronze structure (TTB) as KSr 2 Nb 5 O 15 (KSN) have proved to be of technological interest principally due to the high anisotropy of the crystalline structure and ferroelectric properties with great potential for applications such as sensor devices, actuators, memories, filters and capacitors (wireless communication) [11,12]. Nickelzinc ferrites are typical polycation oxides exhibiting an inverse spinel structure with a complex cation distribution in the crystalline structure.…”

Section: Introductionmentioning

confidence: 99%

Evolution of thermal properties of natural rubber nanocomposites functionalized by nickel–zinc ferrite and potassium strontium niobate nanopowders

Bellucci

Almeida

Agostini

et al. 2016

J Therm Anal Calorim

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Several composites and nanocomposites based on a polymeric matrix and ceramic fillers are being pursued for use as multifunctional and innovative materials. Nevertheless, there is a series of challenges to be solved in this area such as the understanding of the role of interfaces and the synergy between matrix and fillers. In this work, vulcanized natural rubber nanocomposites were prepared with different concentrations of two kinds of ceramic nanoparticles, potassium strontium niobate (KSr 2 Nb 5 O 15 or KSN) and nickel-zinc ferrite (Ni 0.5 Zn 0.5 Fe 2 O 4 or NZF), synthesized by a chemical method known as the modified polyol method. Morphological and thermal characterizations were carried out by AFM, TG/DTG, TG/FTIR and DSC. The thermal properties of nanocomposites were compared and discussed as functions of concentration, type and surface of nanoparticles. The results obtained suggest that the base concentration for both types of nanoparticles inside the polymer matrix volume greatly adds to the increase in thermal stability up to 11 % and the glass transition temperature up to 10°C. A similar evolution for the glass transition temperature (T g), thermal stability temperature (T S) and dielectric permittivity (e 0) was identified, suggesting that these phenomena are mainly dominated by the same mechanisms. These results point to the possibility for the thermal parameter modulation in magnetic and ferroelectric nanocomposites by means of a suitable control of concentration and properties of the KSN and NZF nanoparticles. Keywords Nickel-zinc ferrite Á Potassium strontium niobate Á Functionalized nanocomposites Á Thermal properties Á Thermal stability Á Glass transition temperature & Aldo Eloizo Job

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Section: Introductionmentioning

confidence: 99%

Evolution of thermal properties of natural rubber nanocomposites functionalized by nickel–zinc ferrite and potassium strontium niobate nanopowders

Bellucci

Almeida

Agostini

et al. 2016

J Therm Anal Calorim

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“…The observed softening is mainly related to the shear modulus. 14,30 The symmetry change from Pm3m/Fm3 to R3 at T trans implies an improper ferroelastic anomaly, which corresponds to a step change in the elastic constants through linear-quadratic coupling (eP 2 and eQ 2 ). 6,14 Instead, a continuous softening is observed which reflects the change of the microstructure with temperature.…”

Section: Please Cite This Article As Doi: 101063/15116753mentioning

confidence: 99%

Correlations between elastic, calorimetric, and polar properties of ferroelectric PbSc0.5Ta0.5O3 (PST)

Linyu

Romero

Franco

et al. 2019

Applied Physics Letters

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Calorimetric, elastic, and polar properties of ferrolectric lead scandium tantalate PbSc 0.5 Ta 0.5 O 3 (PST) with 65% cation order have been investigated in the vicinity of the paraelectric-ferroelectric transition at T trans = 295 K. Comparison of temperature dependencies of the excess specific heat and elastic properties indicate that both anomalies stem from thermal fluctuations of order parameters in three dimensions. These fluctuations are consistent with tweed microstructure. This transition is driven by several coupled thermodynamic order parameters, as evidenced by a strongly non-linear scaling of the excess entropy with the squared ferroelectric polarization.Most ferroelectric materials undergo weakly first order transitions between a paraelectric and a ferroelectric phase. These phase transitions are often influenced by the microstructure of the material, 1 which may change depending on the thermal history of the sample and defect concentration. [2][3][4] Therefore, reliable comparisons between thermal, electric, and elastic data require measurements using the same samples. As an example, the step in the thermodynamic enthalpy, as measured by calorimetry, is typically not reported together with equivalent steps in the ferroelectric polarization and a direct comparison of such two data sets is often not possible. Similarly, the scaling between the entropy of the transition and the structural order parameter 5 is the key element for the investigation of 'hidden' order parameters that modify the transition behaviour. This scaling has been investigated thoroughly in ferroelastic materials 6,7 but much less in ferroelectrics. In this paper we report coupling phenomena in PbSc 0.5 Ta 0.5 O 3 (PST), a ferroelectric material where the transition is driven by several order parameters.PST crystallizes in a perovskite structure and is ferroelectric when the degree of cation order Q od is Q od > 0.55. [8][9][10][11] A weakly first order ferroelectric transition occurs at 295-300 K corresponding to a symmetry change from Pm3m/Fm3m to R3. [8][9][10]12,13 Elastic properties of PST with a relatively high degree of B-site order, Q od = 0. 65, were reported over a large temperature interval. 14 These results, along with polar, piezoelectric, dielectric, and structural properties, were interpreted by Landau theory. The proposed Landau model consisted several order parameters, namely, cation order Q od , polarization P, and octahedral tilting Q, which belong to irreducible representations R + 4 , R + 1 , and Γ − 4 , respectively, of the parent space group, Pm3m. Here, the instability in the paraelectric phase due to polarization (P) fluctuations in the Γ point of the Brillouin zone leads to R3m symmetry. The symmetry breaking solely due to P is approximately tricritical as observed

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“…However, during the last few years, the research was mostly directed to the synthesis and characterisation of novel TTB ferroelectric and ferroelectric-related materials [8][9][10][11][12][13][14][15][16][17][21][22][23][24][25][26], with Sr 5 Nb 10 O 30 -Ba 5 Nb 10 O 30 system (SBN) [27] and Ba 6 FeNb 9 O 30 (BFNO) [28][29][30][31] as the main starting point. These ceramic materials exhibit actually relaxor ferroelectric/dielectric phenomena [6,12,[32][33][34][35][36][37]; in the BFNO-related materials, it was shown that due to the variable oxidation state of Fe (Fe 3+ /Fe 2+ ) appear oxygen vacancy gradients, and both low temperature dielectric spectroscopy and high temperature impedance spectroscopy measurements indicated more electroactive regions than anticipated [9,38]. The compositional variables give however even to simple single-phase ceramic materials a complex behaviour, therefore the structural, electrical and relaxor properties of TTBs have to be deeply investigated [10,11,13,21].…”

Section: Introductionmentioning

confidence: 99%

“…The slowing of dipolar response on cooling and the eventual "locking" of the B-cation displacements along the c-axis, (i.e. dipole freezing) was observed [12], while the dynamics of dielectric relaxation of dipoles was extensively investigated by Vogel-Fulcher (VF); the VF fits proved to be very sensitive on the processing parameters [6,36], and the main relaxor behaviour being accompanied by both elastic and anelastic relaxations, as observed by resonance ultrasound spectroscopy (RUS) [37].…”

Section: Introductionmentioning

confidence: 99%

Structural, electrical and relaxor properties of Sc-In solid solution in tetragonal tungsten bronze ceramics

Rotaru

Morrison

2019

Ceramics International

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The electrical properties of a family of tetragonal tungsten bronze (TTB) materials, Ba 6 Sc 1-x In x Nb 9 O 30 (x = 0.25, 0.5, 0.75), which display relaxor properties were characterised using high-temperature impedance spectroscopy and low-temperature dielectric spectroscopy. All powders were synthesized at 1250 °C (24 hours) + 1350 °C (6.5 hours), while the pellets were further sintered at 1350 °C (12 hours). At high temperature, the electrical conductivity in all samples is dominated by a single response, attributed to the bulk response, while the subtle asymmetry of the imaginary impedance peak suggests a minor contribution of the grain boundary response. In general, the Sc-In solid solutions samples exhibit similar electrical behaviour to the Sc compound, x = 1 reported previously (Ceram. Int. 2016, 42, 11810-11821). At low temperature all compounds exhibit frequency dependent relaxor behaviour. With increasing the content of In, the dielectric peaks are more asymmetric and the curves flatten more at temperatures above the transition temperature. The dipole freezing temperature, T VF , determined by Vogel-Fulcher (VF) analysis does not simply increases linearly as a function of M 3+ (Sc 3+ ,In 3+ ) cation size, the extrapolation of VF-like curves results in considerably different values when compared to those found previously, since the acquired dielectric data are very sensitive to preparative conditions.

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Elastic and anelastic relaxations accompanying relaxor ferroelectric behaviour of Ba6GaNb9O30 tetragonal tungsten bronze from resonant ultrasound spectroscopy

Cited by 9 publications

References 72 publications

Evolution of thermal properties of natural rubber nanocomposites functionalized by nickel–zinc ferrite and potassium strontium niobate nanopowders

Evolution of thermal properties of natural rubber nanocomposites functionalized by nickel–zinc ferrite and potassium strontium niobate nanopowders

Correlations between elastic, calorimetric, and polar properties of ferroelectric PbSc0.5Ta0.5O3 (PST)

Structural, electrical and relaxor properties of Sc-In solid solution in tetragonal tungsten bronze ceramics

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