Papers by Keyword: Morphotropic Phase Boundary

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Authors: Ghulam Shabbir, A.H. Qureshi
Abstract: Dielectric properties and structural morphology of the Sc2O3 free and reduced lead content piezoelectric ceramic system, (1-x)Bi(Mg1/2Zr1/2)O3-xPbTiO3 (BMZ-xPT), were investigated in this study. The average grain size of the fresh fractured surfaces was of the order of ≤1 μm to ∼3 μm. The dielectric constant, loss tangent, Curie temperature, remnant polarization, coercive field, piezoelectric coefficient, and the planer coupling constant of ceramics in the vicinity of the morphotropic phase boundary (MPB) (x∼0.55) were, ∼1450, 0.0952, ∼553 K, 29 (μC/cm2) , 23 (kV/cm), ∼185 pC/N, and ∼30%, respectively. It was observed that with decreasing PbTiO3 contents the phase transition anomaly became broadened. The position of the dielectric constant maximum (ε′max) did not show any significant variation with probe frequency, exhibiting character of diffuse phase transition like many other disordered perovskites.
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Authors: Cheng Che Tsai, Hsiang Ho Hsieh, Sheng Yuan Chu, Zong You Chen, S.K. Huang
Abstract: In this study, the (Mn, Sb) co-tuned PbCa0.01[(MnxZn0.1-x)1/3(SbxNb0.1-x)2/3 (Zr0.505Ti0.4895)0.9]O3 (PCZMNSZT-100x) ceramics were prepared near the morphotropic phase boundary (MPB) using the wolframite precursor method. The phase structure evolutions, electrical and temperature stability properties were systematically investigated. As the fraction of rhombohedral phase increases, the degree of disorder in the diffused phase transition (DPT) correspondingly increased and the “hard” piezoelectric characterization would be enhanced. Moreover, the temperature change rate of k, Qm and fr can be tuned by adjusting the x content. The specimens with x=0.08 exhibit the obtained values as kp ~ 0.50, kt ~ 0.52, Qm ~ 1550, and the low temperature change rate of properties having Δfr/fr = -0.02% and ΔQm/Qm = 10.5%, up to 100 °C. To evaluate the material feasibility, the proposed multi-bulk step-down transformers using a ring/dot structure are fabricated. Their obtained electrical properties have a maximum efficiency of 92% with an output power of 15 W, a voltage gain of 0.68 and a nearly zero temperature change rate of resonant frequency are found at the load of 100 Ω.
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Authors: Na Yin, Abolfazl Jalalian, Zhi Gang Gai, Lan Ling Zhao, Xiao Lin Wang
Abstract: Doping effect on the lattice parameters, vibration modes, dielectric and piezoelectric properties of LiSbO3, LiTaO3 and LiNbO3 substituted lead-free K0.5Na0.5NbO3 (KNN) ceramics are investigated. All compositions are crystallized in morphotropic phase boundary region. Enhanced piezoelectric and electromechanical response d33 ~176–197 pC/N, kp ~45%–48%, and kt ~34%–47% obtained in the doped ceramics are due to the presence of the polymorphic phase transition between orthorhombic and tetragonal phase at room temperature.
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Authors: R. Muanghlua, S. Niemchareon, Wanwilai C. Vittayakorn, Naratip Vittayakorn
Abstract: The piezoelectric ceramics of Pb(ZrxTi1−x)O3 – Pb(Zn1/3Nb2/3)O3 – Pb(Mn1/3Nb2/3)O3; PZT-PZN-PMN with Zr/Ti ratios of 48/52, 50/50 and 52/48 were fabricated in order to investigate the effect of compositional modifications on the ferroelectric properties of PZT-PZN-PMN ceramics. The phase structure of ceramics sintered at 1,150°C was analyzed. Results show that the pure perovskite phase was in all ceramic specimens, and the phase structure of PZT-PZN-PMN piezoelectric ceramics transformed from tetragonal to rhombohedral, with the Zr/Ti ratios increased in the system. The PZT-PZN-PMN ceramics with a Zr/Ti ratio of 50/50 exhibited the most promising properties including high remanent polarization and low coercive field of 25.95 µC cm−2 and 12.5 kV cm−1, respectively. Furthermore, the transition temperature decreased when the Zr/Ti ratio increased in the system.
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Authors: Francesco Cordero, Francesco Trequattrini, Floriana Craciun, Elisa Mercadelli, Carmen Galassi
Abstract: The perovskite (Na1/2Bi1/2)TiO3 (NBT) undergoes a series of structural and polar transitions starting from the high temperature paraelectric phase: tetragonal paraelectric, tetragonal antiferroelectric, rhombohedral antiferroelectric and finally rhombohedral ferroelectric, according to neutron diffraction and dielectric spectroscopy. In solid solution with BaTiO3 (BT) the ferroelectric phase changes from rhombohedral to tetragonal, at the so-called morphotropic phase boundary, and the phases at higher temperature become ill-defined, also because of the large lattice disorder induced by the coexistence of differently charged cations in the same sublattice. Combined dielectric and anelastic spectroscopy measurements are presented, which clarify some issues related to the phase transitions in NBT-BT. The influence of Ba substitution on the tetragonal antiferroelectric phase is determined for the first time, and the possibility that a monoclinic phase, although with very short coherence length, exists near the morphotropic phase boundary is discussed in view of a large maximum of the elastic compliance.
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Authors: Guo Yuan Zhou, Jin Song Pan, Xiao Wen Zhang
Abstract: Ferroelectric ceramics of (1x)(0.8PMN0.2PNN)xPT (x = 0.280.43) were synthesized by the columbite precursor method. Their phase structures as well as the dielectric, ferroelectric and piezoelectric properties were investigated. X-ray diffraction (XRD) results demonstrate that the morphotropic phase boundary (MPB) of this system lies in the composition range of x = 0.31–0.37. Examination of the dielectric behavior indicates that the ceramics exhibit high dielectric constants near the MPB compositions. In addition, the piezoelectric properties of the ceramics were found quite well around the MPB. The interrelated mechanism was also discussed.
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Authors: N. Sawangwan, J. Tontrakoon, S. Sirisoonthorn, Tawee Tunkasiri
Abstract: (1-x)(Bi0.5Na0.5TiO3)-xBa(Ti0.95Zr0.05)O3 ceramics were prepared by the mixed oxide technique and their dielectric, piezoelectric and ferroelectric properties determined in detail in the range x = 0.06 to 0.09. At x = 0.07 the maximum relative permittivity of 1338 and piezoelectric constant of 167 pC/N were obtained. It was concluded that 0.93(Bi0.5Na0.5TiO3)-0.07Ba(Ti0.95Zr0.05)O3 is the morphotropic phase boundary region for this system.
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Authors: Rui Lin Wu, Tomoaki Karaki, Jiang Tao Zeng, Liao Ying Zheng, Wei Ruan, Xue Zheng Ruan, Guo Rong Li
Abstract: Lead-based piezoelectric ceramics have excellent piezoelectric properties with the compositions near the rhombohedral-tetragonal morphotropic phase boundary (MPB)[1,2]. In these materials, the dielectric and piezoelectric properties show the maximal values at MPB. For lead-free piezoelectric ceramics, finding the MPB area is a promising way to improve their properties. In this paper, the (1-x-y)BaZrO3-x(K0.45Na0.5Li0.05)NbO3-yBi (Mg0.5Ti0.5)O3 lead-free piezoelectric ceramics were prepared by solid-state reaction method, and their piezoelectric properties and dielectric properties were investigated. With the increase of KNLN content, the crystal structure changed from rombohedral phase to tetragonal phase, thus existed a MPB[3,4] between rombohedral and tetragonal phase. At room temperature, the specimen with the composition at MPB (x=0.93, y=0.01) shows the optimal piezoelectric properties (d33=225pC/N and kp=45%), which indicates that this material is a potential lead-free piezoceramic.
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