Thermal and dynamic mechanical analyses on Bi0.5Na0.5TiO3–BaTiO3 ceramics synthesized with citrate method

Zheng, Xiu Cheng; Zheng, Gengfeng; Lin, Zheng; Jiang, Zhi Yuan

doi:10.1016/j.ceramint.2012.07.052

Cited by 27 publications

(9 citation statements)

References 18 publications

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“…Significantly, a negative ECE larger than 12 °C is found in the nanocomposites consisting of P(VDF-TrFE) and 5% volume fraction of BT nanowires. This ECE is much larger than It is noted that the Q −1 peaks in the mechanical spectra for P(VDF-TrFE) and P(VDF-TrFE)-BT nanocomposites are of the relaxation type, which are different from those frequency-independent Q −1 peaks for a structural transformation usually observed in conventional ferroelectric materials [13,24]. These features of mechanical relaxation thus further demonstrate the existence of glassy polar states in the materials we investigated.…”

Section: Discussionmentioning

confidence: 57%

Exceptionally High Negative Electro-Caloric Effects of Poly(VDF–co–TrFE) Based Nanocomposites Tuned by the Geometries of Barium Titanate Nanofillers

Jiang

Zheng

et al. 2017

Polymers

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Exceptionally high electro-caloric effects (ECEs) are observed in nanocomposites consisting of poly(vinylidene fluoride-co-trifluoroethylene) (VDF-co-TrFE) copolymer and barium titanate (BT) nanoparticles and nanowires. The poly(VDF-co-TrFE) matrix nanocomposites containing 5% volume fraction of BT nanowires are found to exhibit a negative ECE temperature change as large as 12 • C or a refrigeration effect of 8.3 J/g, which is much larger than those reported to date. The mechanisms of negative ECE and the enhanced negative ECE in the nanocomposites consisting of poly(VDF-co-TrFE) and BT nanowires are explained by the Kauzmann theory on glassy polar states and the interaction between BT nanofillers and the copolymer matrix. The effects of geometries of BT nanofillers on the negative ECEs are elucidated by P-E loop measurements, and dielectric and dynamical mechanical analyses. The nanocomposites, with their enhanced negative ECE tuned by the geometries of BT nanofillers, provide us with promising ECE refrigerants for practical application to small-sized and environmentally-friendly ECE coolers in the heat management of electronic devices.

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Section: Discussionmentioning

confidence: 57%

Exceptionally High Negative Electro-Caloric Effects of Poly(VDF–co–TrFE) Based Nanocomposites Tuned by the Geometries of Barium Titanate Nanofillers

Jiang

Zheng

et al. 2017

Polymers

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“…Other reports on DMA experiments have been published, where the frequency dispersion was analyzed in order to extract information on the polarization dynamics [176], and where concentrations up to

x (Ba) = 0.25

have been studied [177]. Recently, a study has been carried out of the Young’s modulus of some FE perovskites measured with the method of the impulse excitation [178].…”

Section: Nbt-based Solid Solutionsmentioning

confidence: 99%

Elastic Properties and Enhanced Piezoelectric Response at Morphotropic Phase Boundaries

Cordero

2015

Materials

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The search for improved piezoelectric materials is based on the morphotropic phase boundaries (MPB) between ferroelectric phases with different crystal symmetry and available directions for the spontaneous polarization. Such regions of the composition x−T phase diagrams provide the conditions for minimal anisotropy with respect to the direction of the polarization, so that the polarization can easily rotate maintaining a substantial magnitude, while the near verticality of the TMPBx boundary extends the temperature range of the resulting enhanced piezoelectricity. Another consequence of the quasi-isotropy of the free energy is a reduction of the domain walls energies, with consequent formation of domain structures down to nanoscale. Disentangling the extrinsic and intrinsic contributions to the piezoelectricity in such conditions requires a high level of sophistication from the techniques and analyses for studying the structural, ferroelectric and dielectric properties. The elastic characterization is extremely useful in clarifying the phenomenology and mechanisms related to ferroelectric MPBs. The relationship between dielectric, elastic and piezoelectric responses is introduced in terms of relaxation of defects with electric dipole and elastic quadrupole, and extended to the response near phase transitions in the framework of the Landau theory. An account is provided of the anelastic experiments, from torsional pendulum to Brillouin scattering, that provided new important information on ferroelectric MPBs, including PZT, PMN-PT, NBT-BT, BCTZ, and KNN-based systems.

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“…For the presumably morphotropic phase boundary (MPB) composition BNT-6BT Cordero et al 26 observed a maximum in the compliance at approximately 190 C, which was confirmed by other authors. 27 The relaxor features of BNT-6BT, however, were not reflected in their analysis, since BNT-6BT at the time was predominantly assumed to be a ferroelectric transforming into an antiferroelectric before it converts into a paraelectric cubic phase. 7 Moreover, the study was limited to the pseudobinary BNT100xBT systems.…”

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confidence: 99%

Local structure change evidenced by temperature-dependent elastic measurements: Case study on Bi1/2Na1/2TiO3-based lead-free relaxor piezoceramics

Dittmer

Webber

et al. 2014

Journal of Applied Physics

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Quenching-induced circumvention of integrated aging effect of relaxor lead lanthanum zirconate titanate and (Bi1/2Na1/2)TiO3-BaTiO3 Appl. Phys. Lett. 102, 032901 (2013) (4BZT) is measured with the impulse excitation technique and contrasted with corresponding dielectric and structural data. While the dielectric properties suggest a phase transition, the high resolution XRD patterns remain virtually unchanged from room temperature up to high temperatures, confirming no change in their long-range order. In contrast, the elastic properties indicate a broad and diffuse ferroelastic transition denoted by a minimum in Y(T). By analogy to the elastic and dielectric data of PbZr x Ti 1Àx O 3 and PLZT, it is concluded that 20BKT and 4BZT are relaxors with polar nanoregions embedded in a metrically cubic matrix. Interestingly, no indication for the freezing temperature was reflected in any of the employed measurement techniques. From the saturation of Y(T), it is suggested that the Burns temperature may be approximated as 700 C. Moreover, it is found that the modification with the ternary end-member BiZn 1/2 Ti 1/2 O 3 results in an increase in Young's modulus. A comparison with the Bi 1/2 Na 1/2 TiO 3 -BaTiO 3 -K 0.5 Na 0.5 NbO 3 yields the same results. V C 2014 AIP Publishing LLC.

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Thermal and dynamic mechanical analyses on Bi0.5Na0.5TiO3–BaTiO3 ceramics synthesized with citrate method

Cited by 27 publications

References 18 publications

Exceptionally High Negative Electro-Caloric Effects of Poly(VDF–co–TrFE) Based Nanocomposites Tuned by the Geometries of Barium Titanate Nanofillers

Exceptionally High Negative Electro-Caloric Effects of Poly(VDF–co–TrFE) Based Nanocomposites Tuned by the Geometries of Barium Titanate Nanofillers

Elastic Properties and Enhanced Piezoelectric Response at Morphotropic Phase Boundaries

Local structure change evidenced by temperature-dependent elastic measurements: Case study on Bi1/2Na1/2TiO3-based lead-free relaxor piezoceramics

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