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R Blinc - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Theory of Nonlinear Response in Relaxor Ferroelectrics
Ferroelectrics, 2020Co-Authors: R Pirc, R Blinc, Zdravko KutnjakAbstract:The dynamic nonlinear response of Relaxor Ferroelectrics is investigated in the framework of the spherical random bond-random field model. A new mechanism of nonlinear response due to the field modulation of the interaction between the polar clusters is introduced. It is shown that this mechanism is dominant in PMN and PLZT, and its contribution to the dynamic nonlinear permittivity is calculated.
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electrocaloric effect in Relaxor Ferroelectrics
Journal of Applied Physics, 2011Co-Authors: R Pirc, R Blinc, Z Kutnjak, Q M ZhangAbstract:A theoretical model for the electrocaloric effect (ECE) in Relaxor Ferroelectrics is presented. By solving a self-consistent relation for the ECE temperature change ΔT and minimizing numerically the mean field free energy for Relaxors, the field and temperature dependence of ΔT is calculated. The corresponding harmonic Landau coefficient a=a(T), which differs from the ferroelectric case by always being positive, is derived from the spherical random bond-random field model, and the fourth-order coefficient b is treated as a phenomenological parameter, which can be either positive or negative. For b<0, a line of field-induced first-order Relaxor-to-ferroelectric phase transitions exists in Relaxors, which terminates at a liquid-vapor type critical point ECP,TCP. The critical behavior close to ECP,TCP is analyzed. It is shown that near the first-order phase transition a temperature or field interval or gap formally appears, where ΔT cannot be found. However, domain formation in the coexistence range should r...
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organic and inorganic Relaxor Ferroelectrics with giant electrocaloric effect
Applied Physics Letters, 2010Co-Authors: Shengguo Lu, Q M Zhang, B Rožic, Z Kutnjak, Xinyu Li, Eugene Furman, Lee J Gorny, Barbara Malic, M Kosec, R BlincAbstract:The electrocaloric effect (ECE) in inorganic thin film and organic Relaxor Ferroelectrics is investigated by directly measuring the ECE around room temperature. The results reveal that giant ECEs can be obtained in the high energy electron irradiated poly(vinylidene fluoride-trifluoroethylene) Relaxor copolymer and in the La-doped Pb(ZrTi)O3 Relaxor ceramic thin films, which are much larger than that from the normal ferroelectric counterparts. The large ECE observed, compared with normal Ferroelectrics, is likely caused by the large number of disordered fluctuating polarization entities in Relaxor Ferroelectrics which can lead to extra entropy contributions and larger ECE.
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Polarization Freezing in Relaxor Ferroelectrics
Ferroelectrics, 2008Co-Authors: R Pirc, R Blinc, Vid BobnarAbstract:A simple mechanism for the freezing of polar nanoregions (PNRs) in Relaxor Ferroelectrics is presented. Using the local thermodynamic stability criterion for the polarizable medium in which the PNRs are embedded, the growth of the PNR correlation radius with decreasing temperature is derived. At the percolation threshold T p an infinite cluster of PNRs is formed, and the relaxation time for its reorientation is shown to obey the Vogel-Fulcher (VF) relation, with T p playing the role of the freezing or VF temperature. The effects of freezing on the dielectric permittivity are briefly discusssed.
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vogel fulcher freezing in Relaxor Ferroelectrics
Physical Review B, 2007Co-Authors: R Pirc, R BlincAbstract:A physical mechanism for the freezing of polar nanoregions (PNRs) in Relaxor Ferroelectrics is presented. Assuming that the activation energy for the reorientation of a cluster of PNRs scales with the mean volume of the cluster, the characteristic relaxation time {tau} is found to diverge as the cluster volume reaches the percolation limit. Applying the mean field theory of continuum percolation, the familiar Vogel-Fulcher equation for the temperature dependence of {tau} is derived.
Craig J Stringer - One of the best experts on this subject based on the ideXlab platform.
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dielectric characteristics of perovskite structured high temperature Relaxor Ferroelectrics the bisco3 pb mg1 3nb2 3 o3 pbtio3 ternary system
Journal of the American Ceramic Society, 2008Co-Authors: Craig J Stringer, T R Shrout, Clive A Randall, Niall J Donnelly, Edward F Alberta, Wesley S HackenbergerAbstract:A new compositional family of Relaxor Ferroelectrics was investigated based on the high-temperature Bi(Me)O 3 -PbTiO 3 ferroelectric perovskite family. Compositions were fabricated near an estimated morphotropic phase boundary (MPB) of the xBiScO 3-y Pb(Mg 1/3 Nb 2/3 )O 3 -zPbTi03 (xBS-yPMN-zPT) ternary system exhibiting high-temperature Relaxor properties of T max ∼250°-350°C and e max ∼10000-24000 at 1 kHz. Analysis of the low-field a.c. permittivity by a Vogel-Fulcher type dependence enabled key parameters of activation energy, E A , and freezing temperature, T f , to be determined. The remanent polarization was studied over a broad temperature range and was observed to show classical ferroelectric square loop hysteresis behavior at temperatures T T max , the deviation temperature, To, was obtained from Curie-Weiss analysis and found to be ∼600°C. A comparison of characteristic electrical properties was made between the high-temperature perovskite Relaxors and the classical complex lead Relaxor compound, Pb(Mg 1/3 Nb 2/3 )O 3 (PMN).
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high temperature perovskite Relaxor Ferroelectrics a comparative study
Journal of Applied Physics, 2007Co-Authors: Craig J Stringer, T R Shrout, Clive A RandallAbstract:The recent discovery of high-temperature piezoelectric ceramics based on Bi(Me′Me″)O3-PbTiO3 solutions have also permitted the development of high-temperature Relaxor Ferroelectrics with ternary solid solutions. One of the high-temperature compositions based on the xBiScO3-yPb(Mg1∕3Nb2∕3)O3-zPbTiO3 (xBS-yPMT-zPT) ternary system exhibited a high permittivity maxima of ∼17 000 and a Tmax of 500–550 K. These materials are compared to complex lead perovskite Relaxor Ferroelectrics by determination of the activation energy, EA, and freezing temperature, Tf, from the Vogel-Fulcher relationship and also a high-temperature deviation temperature, TD, from the Curie-Weiss behavior. It was found that these parameters scale within the perovskite Relaxor systems and from the self-consistent trends of these defining parameters. It is suggested that a general comparison for Relaxor Ferroelectrics may exist. The highest EA, Tf, and TD values all exist within the xBS-yPMT-zPT ternary system within the Relaxor ferroelectri...
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Scaling Parameters in Frustrated Systems: Spin Glasses and Relaxor Ferroelectrics
Japanese Journal of Applied Physics, 2007Co-Authors: Craig J Stringer, T R Shrout, Michael J. Lanagan, Clive A RandallAbstract:Through analysis of low-field AC susceptibility data in Relaxor ferroelectric and magnetic spin glass solids, the key parameters of activation energy, EA, and freezing temperature, Tf, were extracted from the Vogel–Fulcher dependence of the maxima. At higher temperatures the deviation temperature, TD, was obtained from departure of the high temperature Curie–Weiss behavior. Collectively, these parameters were found to scale across different compounds and solid solutions for both the magnetic spin glasses and Relaxor Ferroelectrics.
Clive A Randall - One of the best experts on this subject based on the ideXlab platform.
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dielectric characteristics of perovskite structured high temperature Relaxor Ferroelectrics the bisco3 pb mg1 3nb2 3 o3 pbtio3 ternary system
Journal of the American Ceramic Society, 2008Co-Authors: Craig J Stringer, T R Shrout, Clive A Randall, Niall J Donnelly, Edward F Alberta, Wesley S HackenbergerAbstract:A new compositional family of Relaxor Ferroelectrics was investigated based on the high-temperature Bi(Me)O 3 -PbTiO 3 ferroelectric perovskite family. Compositions were fabricated near an estimated morphotropic phase boundary (MPB) of the xBiScO 3-y Pb(Mg 1/3 Nb 2/3 )O 3 -zPbTi03 (xBS-yPMN-zPT) ternary system exhibiting high-temperature Relaxor properties of T max ∼250°-350°C and e max ∼10000-24000 at 1 kHz. Analysis of the low-field a.c. permittivity by a Vogel-Fulcher type dependence enabled key parameters of activation energy, E A , and freezing temperature, T f , to be determined. The remanent polarization was studied over a broad temperature range and was observed to show classical ferroelectric square loop hysteresis behavior at temperatures T T max , the deviation temperature, To, was obtained from Curie-Weiss analysis and found to be ∼600°C. A comparison of characteristic electrical properties was made between the high-temperature perovskite Relaxors and the classical complex lead Relaxor compound, Pb(Mg 1/3 Nb 2/3 )O 3 (PMN).
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high temperature perovskite Relaxor Ferroelectrics a comparative study
Journal of Applied Physics, 2007Co-Authors: Craig J Stringer, T R Shrout, Clive A RandallAbstract:The recent discovery of high-temperature piezoelectric ceramics based on Bi(Me′Me″)O3-PbTiO3 solutions have also permitted the development of high-temperature Relaxor Ferroelectrics with ternary solid solutions. One of the high-temperature compositions based on the xBiScO3-yPb(Mg1∕3Nb2∕3)O3-zPbTiO3 (xBS-yPMT-zPT) ternary system exhibited a high permittivity maxima of ∼17 000 and a Tmax of 500–550 K. These materials are compared to complex lead perovskite Relaxor Ferroelectrics by determination of the activation energy, EA, and freezing temperature, Tf, from the Vogel-Fulcher relationship and also a high-temperature deviation temperature, TD, from the Curie-Weiss behavior. It was found that these parameters scale within the perovskite Relaxor systems and from the self-consistent trends of these defining parameters. It is suggested that a general comparison for Relaxor Ferroelectrics may exist. The highest EA, Tf, and TD values all exist within the xBS-yPMT-zPT ternary system within the Relaxor ferroelectri...
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Scaling Parameters in Frustrated Systems: Spin Glasses and Relaxor Ferroelectrics
Japanese Journal of Applied Physics, 2007Co-Authors: Craig J Stringer, T R Shrout, Michael J. Lanagan, Clive A RandallAbstract:Through analysis of low-field AC susceptibility data in Relaxor ferroelectric and magnetic spin glass solids, the key parameters of activation energy, EA, and freezing temperature, Tf, were extracted from the Vogel–Fulcher dependence of the maxima. At higher temperatures the deviation temperature, TD, was obtained from departure of the high temperature Curie–Weiss behavior. Collectively, these parameters were found to scale across different compounds and solid solutions for both the magnetic spin glasses and Relaxor Ferroelectrics.
Xifa Long - One of the best experts on this subject based on the ideXlab platform.
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piezo dielectric properties of perovskite structure high temperature Relaxor Ferroelectrics the pb lu1 2nb1 2 o3 pb zn1 3nb2 3 o3 pbtio3 ternary ceramics
Materials Research Bulletin, 2014Co-Authors: Tao Li, Xifa LongAbstract:Abstract A new compositional system of Relaxor Ferroelectrics was investigated based on the high piezoelectricity Pb(Zn 1/3 Nb 2/3 )O 3 –PbTiO 3 ferroelectric perovskite family. Compositions were fabricated near an estimated morphotropic phase boundary (MPB) of the Pb(Lu 1/2 Nb 1/2 )O 3 –Pb(Zn 1/3 Nb 2/3 )O 3 –PbTiO 3 (PLZNT) ternary system by a two-step synthetic process. Their structures have been analyzed by means of X-ray diffraction technique. On the basis of X-ray powder diffraction, the morphotropic phase boundary (MPB) region for the ternary system was obtained. The Curie temperature T C of ternary system varied from 240 °C to 330 °C and the coercive fields E c s > 10 kV/cm. The values of piezoelectric coefficients d 33 vary in the range of 260–450 pC/N with different PZN contents. It is worth noting that the optimum compositions were located at MPB region but near the tetragonal phase. The new PLZNT ceramics exhibit wider range of T C s and E c s, making it a promising material for high-powder ultrasound transducers using in a large temperature range.
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compositional disorder polar nanoregions and dipole dynamics in pb mg1 3nb2 3 o3 based Relaxor Ferroelectrics
Zeitschrift Fur Kristallographie, 2011Co-Authors: A A Bokov, Anna N Morozovska, Brian J Rodriguez, Xiaohui Zhao, Jaehyeon Ko, Stephen Jesse, Xifa Long, Weiguo Qu, J D Budai, Seiji KojimaAbstract:The complex structure of Relaxor Ferroelectrics comprises polar nanoregions (PNRs) which appear upon cooling below the Burns temperature and quenched com- positional (chemical) disorder. The relation between the polar nanostructure and compositionally ordered regions (CORs) often observed in Relaxors has been the subject of extensive theoretical investigations; however, the experi- mental data, especially concerning Pb(B 0=3 B 00=3 )O3-type complex perovskite Relaxors, are rather limited. In this pa- per, we analyse and discuss the results of our recent inves- tigations of the morphology of CORs and the dynamics of PNRs in Pb(Mg1/3Nb2/3)O3-based solid solutions in which the degree of compositional disorder was varied by means of changing the composition and/or by means of high-tem- perature annealing. The samples were characterised using X-ray diffraction, transmission electron microscopy, piezo- response force microscopy, Brillouin light scattering, di- electric spectroscopy, as well as by measuring pyroelectric effect and ferroelectric hysteresis loops. No influence of the size of CORs on the PNRs relaxation in the ergodic Relaxor phase is found. Instead, the CORs size influences significantly the diffuseness of the transition from the field-induced ferroelectric phase to the ergodic Relaxor state. The results are interpreted in the framework of a model suggesting the coexistence of static and dynamic PNRs in the ergodic Relaxor phase.
Nikola Novak - One of the best experts on this subject based on the ideXlab platform.
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Electric field–temperature phase diagram of sodium bismuth titanate-based Relaxor Ferroelectrics
Journal of Materials Science, 2018Co-Authors: Florian Weyland, Jürgen Rödel, Matias Acosta, Malte Vögler, Yoshitaka Ehara, Nikola NovakAbstract:The electric field–temperature phase diagrams of three bismuth sodium titanate-based Relaxor Ferroelectrics are reported, namely 0.94(Na_1/2Bi_1/2TiO_3)–0.06(BaTiO_3), 0.80(Na_1/2Bi_1/2TiO_3)–0.20(K_1/2Bi_1/2TiO_3) and 0.75(Na_1/2Bi_1/2TiO_3)–0.25(SrTiO_3). Relaxor behavior is demonstrated by temperature-dependent dielectric permittivity measurements in the unpoled and poled states, as well as by the field-induced phase transition into a ferroelectric phase from the Relaxor phase. From temperature-dependent thermometry measurements, we identified the threshold electric field to induce the ferroelectric phase and obtained the released latent heat of the phase transition. We determined the nonergodic and ergodic Relaxor phase temperature range based on the absence or presence of reversibility of the Relaxor to ferroelectric transition. For all three compositions, the electric field–temperature phase diagram was constructed and a critical point was identified. The constructed electric field–temperature phase diagrams are useful to find optimum operational ranges of Ferroelectrics and Relaxors for electromechanical and electrocaloric applications.
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Enhancement of Energy Storage Performance by Criticality in Lead-Free Relaxor Ferroelectrics
Physica Status Solidi-rapid Research Letters, 2018Co-Authors: Florian Weyland, Haibo Zhang, Nikola NovakAbstract:In modern electronic systems and energy conversion, efficient capacitors with large energy densities are needed. Relaxor Ferroelectrics show the potential to achieve those requirements. The lead-free Relaxor ferroelectric 0.852(Na1/2Bi1/2TiO3)–0.028(BaTiO3)–0.12(K1/2Bi1/2TiO3) is investigated exhibiting the behavior of a wide range of Na1/2Bi1/2TiO3-based Relaxor systems. The criticality of this system is analyzed and a full electric field–temperature phase diagram is constructed. The energy storage performance is determined from polarization measurements in a wide temperature range. It is found that energy density and especially the efficiency is largely increased in the vicinity of the critical end point of the Relaxor system. The concept of criticality is widely applicable to lead-based and lead-free Relaxor Ferroelectrics and therefore an important approach to increase energy storage performance in those systems.
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electric field temperature phase diagram of sodium bismuth titanate based Relaxor Ferroelectrics
Journal of Materials Science, 2018Co-Authors: Florian Weyland, Jürgen Rödel, Matias Acosta, Malte Vögler, Yoshitaka Ehara, Nikola NovakAbstract:The electric field–temperature phase diagrams of three bismuth sodium titanate-based Relaxor Ferroelectrics are reported, namely 0.94(Na1/2Bi1/2TiO3)–0.06(BaTiO3), 0.80(Na1/2Bi1/2TiO3)–0.20(K1/2Bi1/2TiO3) and 0.75(Na1/2Bi1/2TiO3)–0.25(SrTiO3). Relaxor behavior is demonstrated by temperature-dependent dielectric permittivity measurements in the unpoled and poled states, as well as by the field-induced phase transition into a ferroelectric phase from the Relaxor phase. From temperature-dependent thermometry measurements, we identified the threshold electric field to induce the ferroelectric phase and obtained the released latent heat of the phase transition. We determined the nonergodic and ergodic Relaxor phase temperature range based on the absence or presence of reversibility of the Relaxor to ferroelectric transition. For all three compositions, the electric field–temperature phase diagram was constructed and a critical point was identified. The constructed electric field–temperature phase diagrams are useful to find optimum operational ranges of Ferroelectrics and Relaxors for electromechanical and electrocaloric applications.
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compressible spherical dipolar glass model of Relaxor Ferroelectrics
Journal of Applied Physics, 2012Co-Authors: R Pirc, Z Kutnjak, Nikola NovakAbstract:The interactions between the dielectric polarization and the fluctuations of the strain (stress) tensor in Relaxor Ferroelectrics are shown to give rise to the anisotropy of the anharmonic P4-term in the Landau-type free energy; however, the harmonic P2-term is still properly described by the rigid spherical random bond–random field model. These are the essential features of the compressible spherical dipolar glass model, which is used to calculate the singularities of the specific heat near field-induced critical points. The results agree with recent high-resolution calorimetric experiments in PMN [110].
