The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Xiaojie Lou - One of the best experts on this subject based on the ideXlab platform.
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Enhanced electrocaloric effect near polymorphic Phase Boundary in lead-free potassium sodium niobate ceramics
Applied Physics Letters, 2017Co-Authors: Xiangjian Wang, Brahim Dkhil, Xiaopeng Wang, Guohua Dong, Guang Yang, Xiaojie LouAbstract:The electrocaloric (EC) effect in lead-free (1-x)(K0.48Na0.52)(Nb0.95Sb0.05)O3-xBi0.5(Na0.82K0.18)0.5ZrO3 ceramics was investigated using an indirect thermodynamic method. Large EC temperature changes were obtained in the vicinity of a polymorphic Phase Boundary at 40 kV/cm, e.g., 0.32 K at 359 K for x = 0.03, 0.51 K at 350 K for x = 0.04, and 0.48 K at 300 K for x = 0.05, respectively. These values are larger than the previous results at inter-ferroelectric Phase transition and, more interestingly, are found to be comparable to those usually explored at the Curie temperature. The operational temperature window is broad near the polymorphic Phase Boundary due to the diffuseness of the Phase transition. The enhanced electrocaloric effect is attributed to the formation of nanodomains near the polymorphic Phase Boundary, which reduces domain wall energy and facilitates the polarization rotation. The construction of a polymorphic Phase Boundary and the arrangement of coexisting Phases at the nanoscale may open a promising route to explore EC materials. © 2017 Author(s).
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Composition-Driven Phase Boundary and Piezoelectricity in Potassium–Sodium Niobate-Based Ceramics
ACS applied materials & interfaces, 2015Co-Authors: Ting Zheng, Dingquan Xiao, Jianguo Zhu, Xiangjian Wang, Xiaojie LouAbstract:The piezoelectricity of (K,Na)NbO3 ceramics strongly depends on the Phase Boundary types as well as the doped compositions. Here, we systematically studied the relationships between the compositions and Phase Boundary types in (K,Na) (Nb,Sb)O3–Bi0.5Na0.5AO3 (KNNS-BNA, A = Hf, Zr, Ti, Sn) ceramics; then their piezoelectricity can be readily modified. Their Phase Boundary types are determined by the doped elements. A rhombohedral-tetragonal (R–T) Phase Boundary can be driven in the compositions range of 0.035 ≤ BNH ≤ 0.040 and 0.035 ≤ BNZ ≤ 0.045; an orthorhombic-tetragonal (O–T) Phase Boundary is formed in the composition range of 0.005 ≤ BNT ≤ 0.02; and a pure O Phase can be only observed regardless of BNS content (≤0.01). In addition, the Phase Boundary types strongly affect their corresponding piezoelectricities. A larger d33 (∼440–450 pC/N) and a higher d33* (∼742–834 pm/V) can be attained in KNNS-BNA (A = Zr and Hf) ceramics due to the involvement of R–T Phase Boundary, and unfortunately KNNS-BNA (A =...
Yoshihiro Ishibashi - One of the best experts on this subject based on the ideXlab platform.
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Coexistence States near the Morphotropic Phase Boundary
Japanese Journal of Applied Physics, 2012Co-Authors: Makoto Iwata, Yoshihiro IshibashiAbstract:A model of coexistence states near the morphotropic Phase Boundary (MPB) in perovskite-type ferroelectric crystals was studied using a simplified simulation based on the Landau–Ginzburg-type free energy functional. It was found that, even when no imperfection causing the random field exists, a stable Phase and a metastable Phase coexist near MPB. The coexistence state in the engineered domain configuration near MPB was also found.
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Anisotropy of piezoelectricity near morphotropic Phase Boundary in perovskite-type oxide ferroelectrics
Ferroelectrics, 2002Co-Authors: Makoto Iwata, Hiroshi Orihara, Yoshihiro IshibashiAbstract:Angle dependence of the piezoelectric displacement along the driving electric field was calculated near the morphotropic Phase Boundary in the perovskite-type oxide family on the basis of the Landau-Devonshire type free energy function. It was found that the piezoelectric displacement in the tetragonal Phase near the morphotropic Phase Boundary takes a maximum when the field is applied along the [111] direction, while the piezoelectric displacement in the rhombohedral Phase takes a maximum in the direction, which depends on the values of the elastic and electrostrictive constants. In both Phases the piezoelectric displacements are strongly enhanced near the morphotropic Phase Boundary.
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Theory of the Morphotropic Phase Boundary
Ferroelectrics, 2001Co-Authors: Yoshihiro IshibashiAbstract:A Landau theory is presented for the morphotropic Phase boundaries in the solid solution system of perovskite-type oxide ferroelectrics. The origin of useful functions of materials located close to the morphotropic Phase Boundary are attributed to the isotropy of the thermodynamic potential. In the vicinity of the morphotropic Phase Boundary the electric and the elastic compliances will be extremely large, and the coercive field may become extremely small, due to the instability against the transversal fluctuations.
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Theory of Morphotropic Phase Boundary in Solid Solution Systems of Perovskite-Type Oxide Ferroelectrics: p-e Hysteresis Loop
Japanese Journal of Applied Physics, 1999Co-Authors: Makoto Iwata, Yoshihiro IshibashiAbstract:The p-e hysteresis loop near the morphotropic Phase Boundary in the perovskite-type oxide solid solution system is discussed on the basis of a Landau-type free energy function. It was found that the coercive field in the p-e hysteresis loop decreases upon approaching the morphotropic Phase Boundary and vanishes at the morphotropic Phase Boundary, because of the instability in the direction perpendicular to the polarization.
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a theory of morphotropic Phase Boundary in solid solution systems of perovskite type oxide ferroelectrics
Japanese Journal of Applied Physics, 1999Co-Authors: Yoshihiro Ishibashi, Makoto IwataAbstract:The origin of the appearance of the morphotropic Phase Boundary in perovskite-type oxide solid solution systems is clarified on the basis of a Landau-type free-energy function expressed in terms of polarization and strain components. The dielectric susceptibilities and piezoelectric constants are shown to increase in the vicinity of the morphotropic Phase Boundary.
Xiangjian Wang - One of the best experts on this subject based on the ideXlab platform.
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enhanced electrocaloric effect near polymorphic Phase Boundary in lead free potassium sodium niobate ceramics
Applied Physics Letters, 2017Co-Authors: Xiangjian Wang, Jiagang Wu, Brahim Dkhil, Baixiang Xu, Xiaopeng Wang, Guohua Dong, Guang YangAbstract:The electrocaloric (EC) effect in lead-free (1-x)(K0.48Na0.52)(Nb0.95Sb0.05)O3-xBi0.5(Na0.82K0.18)0.5ZrO3 ceramics was investigated using an indirect thermodynamic method. Large EC temperature changes were obtained in the vicinity of a polymorphic Phase Boundary at 40 kV/cm, e.g., 0.32 K at 359 K for x = 0.03, 0.51 K at 350 K for x = 0.04, and 0.48 K at 300 K for x = 0.05, respectively. These values are larger than the previous results at inter-ferroelectric Phase transition and, more interestingly, are found to be comparable to those usually explored at the Curie temperature. The operational temperature window is broad near the polymorphic Phase Boundary due to the diffuseness of the Phase transition. The enhanced electrocaloric effect is attributed to the formation of nanodomains near the polymorphic Phase Boundary, which reduces domain wall energy and facilitates the polarization rotation. The construction of a polymorphic Phase Boundary and the arrangement of coexisting Phases at the nanoscale may ope...
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Enhanced electrocaloric effect near polymorphic Phase Boundary in lead-free potassium sodium niobate ceramics
Applied Physics Letters, 2017Co-Authors: Xiangjian Wang, Brahim Dkhil, Xiaopeng Wang, Guohua Dong, Guang Yang, Xiaojie LouAbstract:The electrocaloric (EC) effect in lead-free (1-x)(K0.48Na0.52)(Nb0.95Sb0.05)O3-xBi0.5(Na0.82K0.18)0.5ZrO3 ceramics was investigated using an indirect thermodynamic method. Large EC temperature changes were obtained in the vicinity of a polymorphic Phase Boundary at 40 kV/cm, e.g., 0.32 K at 359 K for x = 0.03, 0.51 K at 350 K for x = 0.04, and 0.48 K at 300 K for x = 0.05, respectively. These values are larger than the previous results at inter-ferroelectric Phase transition and, more interestingly, are found to be comparable to those usually explored at the Curie temperature. The operational temperature window is broad near the polymorphic Phase Boundary due to the diffuseness of the Phase transition. The enhanced electrocaloric effect is attributed to the formation of nanodomains near the polymorphic Phase Boundary, which reduces domain wall energy and facilitates the polarization rotation. The construction of a polymorphic Phase Boundary and the arrangement of coexisting Phases at the nanoscale may open a promising route to explore EC materials. © 2017 Author(s).
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Composition-Driven Phase Boundary and Piezoelectricity in Potassium–Sodium Niobate-Based Ceramics
ACS applied materials & interfaces, 2015Co-Authors: Ting Zheng, Dingquan Xiao, Jianguo Zhu, Xiangjian Wang, Xiaojie LouAbstract:The piezoelectricity of (K,Na)NbO3 ceramics strongly depends on the Phase Boundary types as well as the doped compositions. Here, we systematically studied the relationships between the compositions and Phase Boundary types in (K,Na) (Nb,Sb)O3–Bi0.5Na0.5AO3 (KNNS-BNA, A = Hf, Zr, Ti, Sn) ceramics; then their piezoelectricity can be readily modified. Their Phase Boundary types are determined by the doped elements. A rhombohedral-tetragonal (R–T) Phase Boundary can be driven in the compositions range of 0.035 ≤ BNH ≤ 0.040 and 0.035 ≤ BNZ ≤ 0.045; an orthorhombic-tetragonal (O–T) Phase Boundary is formed in the composition range of 0.005 ≤ BNT ≤ 0.02; and a pure O Phase can be only observed regardless of BNS content (≤0.01). In addition, the Phase Boundary types strongly affect their corresponding piezoelectricities. A larger d33 (∼440–450 pC/N) and a higher d33* (∼742–834 pm/V) can be attained in KNNS-BNA (A = Zr and Hf) ceramics due to the involvement of R–T Phase Boundary, and unfortunately KNNS-BNA (A =...
Jae-ho Jeon - One of the best experts on this subject based on the ideXlab platform.
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Stabilities and piezoelectric properties of morphotropic Phase Boundary composition 0.2Pb(Mg_1/3Nb_2/3)O_3–0.38PbZrO_3–0.42PbTiO_3 ternary piezoceramics
Journal of Materials Science, 2019Co-Authors: Ashutosh Upadhyay, Jae-ho JeonAbstract:The Phase stabilities and piezoelectric properties of morphotropic Phase Boundary ternary piezoceramics (0.2Pb(Mg_1/3Nb_2/3)O_3–0.38PbZrO_3–0.42PbTiO_3) are investigated as a function of sintering conditions. The tetragonality ( c / a ) of the morphotropic Phase Boundary, where the rhombohedral and tetragonal Phases coexist (space groups R 3 m and P 4 mm , respectively), is affected by the sintering temperature and time. This tetragonality affects the piezoelectric properties. The results demonstrate that a large tetragonality is undesirable for the piezoelectric properties. The structure and properties of morphotropic Phase Boundary piezoelectric materials are strongly correlated.
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Stabilities and piezoelectric properties of morphotropic Phase Boundary composition 0.2Pb(Mg1/3Nb2/3)O3–0.38PbZrO3–0.42PbTiO3 ternary piezoceramics
Journal of Materials Science, 2019Co-Authors: Ashutosh Upadhyay, Jae-ho JeonAbstract:The Phase stabilities and piezoelectric properties of morphotropic Phase Boundary ternary piezoceramics (0.2Pb(Mg1/3Nb2/3)O3–0.38PbZrO3–0.42PbTiO3) are investigated as a function of sintering conditions. The tetragonality (c/a) of the morphotropic Phase Boundary, where the rhombohedral and tetragonal Phases coexist (space groups R3m and P4mm, respectively), is affected by the sintering temperature and time. This tetragonality affects the piezoelectric properties. The results demonstrate that a large tetragonality is undesirable for the piezoelectric properties. The structure and properties of morphotropic Phase Boundary piezoelectric materials are strongly correlated.
Makoto Iwata - One of the best experts on this subject based on the ideXlab platform.
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Coexistence States near the Morphotropic Phase Boundary
Japanese Journal of Applied Physics, 2012Co-Authors: Makoto Iwata, Yoshihiro IshibashiAbstract:A model of coexistence states near the morphotropic Phase Boundary (MPB) in perovskite-type ferroelectric crystals was studied using a simplified simulation based on the Landau–Ginzburg-type free energy functional. It was found that, even when no imperfection causing the random field exists, a stable Phase and a metastable Phase coexist near MPB. The coexistence state in the engineered domain configuration near MPB was also found.
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Anisotropy of piezoelectricity near morphotropic Phase Boundary in perovskite-type oxide ferroelectrics
Ferroelectrics, 2002Co-Authors: Makoto Iwata, Hiroshi Orihara, Yoshihiro IshibashiAbstract:Angle dependence of the piezoelectric displacement along the driving electric field was calculated near the morphotropic Phase Boundary in the perovskite-type oxide family on the basis of the Landau-Devonshire type free energy function. It was found that the piezoelectric displacement in the tetragonal Phase near the morphotropic Phase Boundary takes a maximum when the field is applied along the [111] direction, while the piezoelectric displacement in the rhombohedral Phase takes a maximum in the direction, which depends on the values of the elastic and electrostrictive constants. In both Phases the piezoelectric displacements are strongly enhanced near the morphotropic Phase Boundary.
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Theory of Morphotropic Phase Boundary in Solid Solution Systems of Perovskite-Type Oxide Ferroelectrics: p-e Hysteresis Loop
Japanese Journal of Applied Physics, 1999Co-Authors: Makoto Iwata, Yoshihiro IshibashiAbstract:The p-e hysteresis loop near the morphotropic Phase Boundary in the perovskite-type oxide solid solution system is discussed on the basis of a Landau-type free energy function. It was found that the coercive field in the p-e hysteresis loop decreases upon approaching the morphotropic Phase Boundary and vanishes at the morphotropic Phase Boundary, because of the instability in the direction perpendicular to the polarization.
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a theory of morphotropic Phase Boundary in solid solution systems of perovskite type oxide ferroelectrics
Japanese Journal of Applied Physics, 1999Co-Authors: Yoshihiro Ishibashi, Makoto IwataAbstract:The origin of the appearance of the morphotropic Phase Boundary in perovskite-type oxide solid solution systems is clarified on the basis of a Landau-type free-energy function expressed in terms of polarization and strain components. The dielectric susceptibilities and piezoelectric constants are shown to increase in the vicinity of the morphotropic Phase Boundary.
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morphotropic Phase Boundary in solid solution systems of perovskite type oxide ferroelectrics
Japanese Journal of Applied Physics, 1998Co-Authors: Yoshihiro Ishibashi, Makoto IwataAbstract:The origin of the appearance of the morphotropic Phase Boundary in the perovskite-type oxide solid solution systems and the increase in the dielectric susceptibilities in the vicinity of the Boundary is theoretically clarified on the basis of a Landau-type free energy function. The dielectric susceptibilities are concretely expressed in terms of the model parameters, and found to diverge at the morphotropic Phase Boundary within the present model.
