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1.
Sanu K. Gupta Brady J. Gibbons Peter Mardilovich David P. Cann 《Journal of the American Ceramic Society》2021,104(3):1592-1600
The solid solution (1 − x)[Bi1/2(Na1/2K1/2)1/2TiO3]-xPbZrO3, (0.00 ≤ x ≤ 0.12) was investigated to examine the phase equilibria, dielectric and electromechanical properties. The composition corresponding to x = 0.00 exhibits tetragonal symmetry with the expected classical ferroelectric (FE) behavior. The system exhibited FE to relaxor crossover with the addition of lead zirconate at the composition x = 0.05. This is indicated by typical relaxor characteristics such as a transition to the global pseudocubic phase, a constriction in the FE hysteresis loop, and a sudden decrease in the negative strain accompanied by an increase in maximum strain. Most notably, with a further increase in x (>0.05), there is evidence for a return to a FE phase that exhibits classical FE characteristics. The combined results demonstrate that there exists a narrow FE-relaxor boundary near x = 0.05, where FE and relaxor phases coexist. At the critical composition, enhancement in the piezoelectric properties, including an increase in the effective (350 pm/V) was observed. This transition in the electromechanical properties is consistent with changes observed in the phase equilibria for this solid solution. The crystal structure transitions from tetragonal symmetry for x = 0.00, to pseudocubic symmetry for the relaxor compositions (x = 0.05), and finally to a lower symmetry perovskite phase for the re-entrant FE phase (x> 0.05). This composition-induced transition from FE to relaxor to a re-entrant FE state in the (1 − x)[Bi1/2(Na1/2K1/2)1/2TiO3]-xPbZrO3 system is unusual among relaxor FE systems and thus is of great scientific and technological interest. 相似文献
2.
Haijuan Li Jian Zhuang Alexei A. Bokov Nan Zhang Jie Zhang Jinyan Zhao Wei Ren Zuo-Guang Ye 《Journal of the European Ceramic Society》2021,41(1):310-318
Mutiferroic materials like bismuth ferrite BiFeO3 have attracted much interest in the last decade due to their promising potential for such applications as spintronics and magnetoelectric data storage devices. On the other hand, relaxor ferroelectrics have been intensively studied for their complex structures with quenched disorder and polar nanoregions which play an important role in their outstanding piezoelectric performance. Much less studied are the single-phase multiferroics that exhibit ferroelectric and/or magnetic relaxor behavior and the correlation between their structure and intricate magneto-electric interactions. In this work, we investigate the evolution of the structure and relaxor behavior in the solid solution between the complex perovskite multirelaxor Pb(Fe2/3W1/3)O3 [PFW] and canonical multiferroic BiFeO3 [BFO], (1-x)PFW-xBFO (with a solubility limit of x = 0.30). The temperature dependences of the dielectric permittivity and loss tangent measured in the frequency range from 100 Hz to 1 MHz indicate characteristic relaxor ferroelectric properties for compositions of x ≤ 0.15, with a frequency-dependent dielectric permittivity peak and its temperature, Tm, satisfying the Vogel-Fulcher law. Detailed studies of the evolution of the relaxor behavior with composition reveal that Tm decreases firstly with a small amount (x = 0.05) of BFO substitution and then increases with further increase of BFO concentration. The degree of relaxor character, as defined by ΔTm [Tm (1 MHz) - Tm (100 Hz)], increases monotonously with increasing BFO content, signifying an enhancement of relaxor behavior with BFO substitution, which is confirmed by the Lorenz-type quadratic variation of the static permittivity. A temperature - composition phase diagram is constructed in terms of the characteristic Burns temperature (TB) and freezing temperature (Tf), which delimits a paraelectric state (PE) above TB, a non-ergotic relaxor state (NR) below Tf, and an ergotic relaxor state (ER) in between. The observed enhancement of relaxor behavior is explained by an increase in the number and size distribution of polar nanoregions in the ER phase, resulting from increased compositional and charge disorders as a result of BFO substitution. The evolution of relaxor behavior and its microscopic mechanisms studied in this work are insightful for a better understanding the multirelaxor properties in multiferroics. Moreover, further substitution of BFO (x ≥ 0.2) flattens the permittivity curves and leads to a temperature-stable variation of high dielectric constant (≈ 103) in a wide temperature range, making the PFW-BFO solid solution attractive for such applications as high energy density capacitors. 相似文献
3.
Na Won Kim Hae Won Lee Muniyandi Muneeswaran Minseong Kim Donghun Kang Minseong Ko Woo Hyun Nam Young Soo Lim 《Journal of the American Ceramic Society》2022,105(9):5751-5763
We report excellent electrostrain properties of (1 − x)BaTiO3–xSrSnO3 (BSTS) Pb-free electroceramics (0 ≤ x ≤ 0.15), as well as the corresponding structural, dielectric, and ferroelectric properties. A tailored phase diagram of the pseudo-binary solid solution of BaTiO3–SrSnO3, which exhibits a nearly composition-independent orthorhombic–tetragonal polymorphic phase boundary close to room temperature, was obtained, and, in contrast to Ba(Ti1−xSnx)O3, the appearance of the relaxor mode was accelerated in the phase transition of BSTS owing to the additional incorporation of Sr. Using these compositionally modified phase-related characteristics, desirable sets of electrostrain properties for actuator applications were obtained. Based on these results, we propose that BSTS is a promising candidate for Pb-free electroceramics for high-precision actuator applications near room temperature. 相似文献
4.
Zhuowei Li Ge Zhu Yu Li Miao Gao Heng Dai Yuehui Yan Faguang Zhou Chuang Wang Shuangyu Xin 《Journal of the American Ceramic Society》2021,104(6):2655-2668
The optical-magnetic multifunctional materials are of great importance owing to their potential applications in intersect discipline fields. However, the multifunctional materials with satisfied optical and magnetic property are limited, and the modulation mechanism of their magneto-optical property related to their structure feature is ambiguous. Here, a new multifunctional solid solution phosphors Ca18K3Sc1-xSmx(PO4)14 (0 ≤ x ≤ 1) are designed based on composition engineering and are successfully synthesized. The detailed structure feature including the structural evolution of the crystallographic parameters and local lattice environment as well as polyhedral distortion behavior are investigated through X-ray diffraction Rietveld structure refinement for Ca18K3Sc1-xSmx(PO4)14 in the full range (0 ≤ x ≤ 1). The photoluminescence spectra indicate that Ca18K3Sc1-xSmx(PO4)14 (0 ≤ x ≤ 1) can emit intense orange-red emission (IQE~42.6%) under ultraviolet light excitation ascribed to the4G5/2 -6H7/2 transition of Sm3+ ions. The structure modulated luminescence behavior, for example, the tunable emission ratio of I648/I565, high quenching content, and electric multipole interaction mechanism are studied. The versatile phosphors can exhibit tunable orange-red cathodoluminescence emission along with increasing the accelerating voltage. The electron transition mechanism of the photoluminescence and cathodoluminescence behavior is further discussed through a simple schematic diagram. Moreover, Ca18K3Sc1-xSmx(PO4)14 (0 ≤ x ≤ 1) shows a ferromagnetic behavior with controllable magnetization and coercive field. Finally, the impact of Fe ions on the photoluminescence and magnetic property of Ca18K3Sc1-yFey(PO4)14: 0.4Sm3+ (0 ≤ y ≤ 0.05 and y = 1) phosphors are investigated. The current research can provide some ideas and mechanism to design and investigate more novel magneto-optical muntifunctional materials for versatile applications in intersect disciplines. 相似文献
5.
Xuechen Huang Hua Hao Shujun Zhang Hanxing Liu Wenqin Zhang Qi Xu Minghe Cao 《Journal of the American Ceramic Society》2014,97(6):1797-1801
(1?x)BaTiO3–xBiYO3 [(1?x)BT–xBY] polycrystalline ceramics were prepared by solid‐state reaction method. The ceramics are in tetragonal phase when x ≤ 0.04, transform to pseudocubic at x ≥ 0.06, showing a classic ferroelectric to relaxor transition at x = 0.06, where the phase transition temperature was found to shift to higher temperature with increasing frequency. The dielectric permittivity peaks were analyzed by the modified Curie–Weiss law. Both parameters ΔTdiffuse and ΔTrelaxor were found to increase with increasing BY content, demonstrating a stronger relaxor characteristic. 相似文献
6.
Kang Du Chang-Zhi Yin Yan-Bo Guo Xiao-Chuan Wang Wen-Zhong Lu Shi-Wo Ta Chun-Yuan Hu Wen Lei 《Journal of the American Ceramic Society》2022,105(2):1253-1264
Ca3SnSi2-xGexO9 (0 ≤ x ≤ 0.8) and (1–y) Ca3SnSi1.6Ge0.4O9 – y CaSnSiO5 – 2 wt% LiF (y = 0.4 and 0.5) microwave dielectric ceramics were prepared by traditional solid-state reaction through sintering at 1250°C–1425°C for 5 h and at 875°C for 2 h, respectively. Ge4+ replaced Si4+, and Ca3SnSi2-xGexO9 (0 ≤ x ≤ 0.4) solid solutions were obtained. At 0.1 ≤ x ≤ 0.4, the Ge4+ substitution for Si4+ decreased the sintering temperature of Ca3SnSi2-xGexO9 from 1425 to 1300°C, the SnO6 octahedral distortions, and the average CaO7 decahedral distortions, which affected the τf value. The large average decahedral distortions corresponded with nearer-zero τf values at Ca3SnSi2-xGexO9 (0.1 ≤ x ≤ 0.4) ceramics. The τf value and sintering temperature of Ca3SnSi2-xGexO9 (x = 0.4) ceramic were adjusted to near-zero by CaSnSiO5 and decreased to 875°C upon the addition of 2 wt% LiF. The (1 – y) Ca3SnSi1.6Ge0.4O9 – y CaSnSiO5 – 2 wt% LiF (y = 0.5) ceramic sintered at 875°C for 2 h exhibited good microwave dielectric properties: εr = 10.3, Q × f = 14 300 GHz (at 12.2 GHz), and τf = ‒5.8 ppm/°C. 相似文献
7.
《Ceramics International》2022,48(22):33219-33228
In this work, the Pb(Fe1-xCox)2/3W1/3O3 (PFCW) and Pb(Co1-yFey)1/2W1/2O3 (PCFW) ceramics with 0 ≤ x, y ≤ 1 were successfully fabricated by a solid-state reaction process. X–ray diffraction phase analysis indicate the formation of two different series of solid solutions with a perovskite structure and with the substitution limits of Fe for Co (in PFCW) and Co for Fe (in PCFW) are x = 0.35 and y ≈ 0.05, respectively. Based on the results of dielectric study of the PFCW ceramics, it was shown that a crossover from relaxor ferroelectric to ferroelectric with a diffuse phase transition takes place at x = 0.10. In the case of PCFW ceramics, the observed dielectric maxima correspond to the phase transitions at 320 K and 256 K. The peculiarities of the temperature dependencies of the thermally stimulated depolarization currents of PFCW and PCFW solid solutions were studied and discussed. 相似文献
8.
Guanhua Song Faqiang Zhang Feng Liu Zhifu Liu Yongxiang Li 《Journal of the American Ceramic Society》2021,104(8):4049-4057
SrTiO3-modified lead-free piezoelectric ceramics, (0.93-x)Bi0.5Na0.5TiO3-xSrTiO3-0.06BaTiO3-0.01 K0.5Na0.5NbO3 [(BNT-xST)-BT-KNN, x = 0-0.06], were prepared using a conventional solid-state reaction method. The XRD structure analysis and electric properties characteristics revealed the ST-induced phase transformation from the ferroelectric phase to the relaxor phase and their coexistence state. Benefiting from the ST-destructed ferroelectric long-range orders, the high normalized strain value of 600 pm/V was obtained in the (BNT-0.02ST)-BT-KNN ceramic at 5 kV/mm. The ST-generated relaxor phase was found to have a constructive effect on improving the temperature stability and restraining the hysteresis of the electric-field-induced strain. The normalized strain of (BNT-0.06ST)-BT-KNN ceramics could be kept at a high value ~337 pm/V at elevated temperature up to 120°C. 相似文献
9.
Composition‐ and Temperature‐Dependent Large Strain in (1−x)(0.8Bi0.5Na0.5TiO3–0.2Bi0.5K0.5TiO3)– xNaNbO3 Ceramics
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Guangzhi Dong Huiqing Fan Jing Shi Mengmeng Li 《Journal of the American Ceramic Society》2015,98(4):1150-1155
Ternary solid solutions of (1 ? x)(0.8Bi0.5Na0.5TiO3–0.2Bi0.5K0.5TiO3)– xNaNbO3 (BNKT–xNN) lead‐free piezoceramics were fabricated using a conventional solid‐state reaction method. Pure BNKT composition exhibited an electric‐field‐induced irreversible structural transition from pseudocubic to ferroelectric rhombohedral phase at room temperature. Accompanied with the ferroelectric‐to‐relaxor temperature TF‐R shifted down below room temperature as the substitution of NN, a compositionally induced nonergodic‐to‐ergodic relaxor transition was presented, which featured the pinched‐shape polarization and sprout‐shape strain hysteresis loops. A strain value of ~0.445% (under a driving field of 55 kV/cm) with large normalized strain of ~810 pm/V was obtained for the composition of BNKT–0.04NN, and the large strain was attributed to the reversible electric‐field‐induced transition between ergodic relaxor and ferroelectric phase. 相似文献
10.
Shuaishuai Ji Qianjie Li Dongdong Wang Jiangyuan Zhu Min Zeng Zhipeng Hou Zhen Fan Xingsen Gao Xubing Lu Qiliang Li Jun-Ming Liu 《Journal of the American Ceramic Society》2021,104(6):2646-2654
Lead-free (1-x)BiFeO3-x(0.85BaTiO3-0.15Bi(Sn0.5Zn0.5)O3) [(1-x)BF-x(BT-BSZ), x=0.45-0.7] ceramic samples were prepared by solid phase sintering. It is revealed that the pure single-phase perovskite structure can be obtained in samples with x ≥ 0.6. With increasing x, the measured ferroelectric hysteresis loop becomes gradually slimmed in accompanying with reduced remnant polarization, and a clear ferroelectric-relaxor transition at x = 0.65 is identified. Furthermore, the measured electric breakdown strength can be significantly enhanced with increasing x, and the optimal energy storage performance is achieved at x = 0.65, characterized by the recoverable energy storage density up to ≈3.06 J/cm3 and energy storage efficiency as high as ≈92 %. Excellent temperature stability (25°C–110°C) and fatigue endurance (>105 cycles) for energy storage are demonstrated. Our results suggest that the BF-based relaxor ceramics can be tailored for promising applications in high energy storage devices. 相似文献
11.
Narit Triamnak Rattikorn Yimnirun Jan Pokorny David P. Cann 《Journal of the American Ceramic Society》2013,96(10):3176-3182
The single‐phase solid solutions of the (1 ? x)BaTiO3–(x)Bi(Zn1/2Ti1/2)O3 (BT–BZT) where x = 0.02–0.15 were prepared to investigate dielectric properties. Crystal structure of samples was obtained by using an X‐ray diffraction technique and Raman spectroscopy. For compositions with x ≤ 0.08, the solid solutions exhibited clear tetragonal symmetry and transitioned to pseudocubic symmetry as the content of BZT increased. The dielectric response exhibited a sharp phase transition within the BT‐rich region and the composition 0.92BT–0.08BZT was characterized by the onset of relaxor characteristics. As the concentration of BZT increased, the phase transition exhibited broader and more diffuse behavior. The polarization as a function of electric field (P–E) of these solid solutions also exhibited the same trend. The BT‐rich compositions showed a normal ferroelectric P–E response with a decrease in loop area as the BZT content increased. The composition at x = 0.08 exhibited a pinched hysteresis loop and with further increase in BZT content, the P–E response was characterized by slim loops. 相似文献
12.
Phase Evolution,Magnetic, Optical,and Dielectric Properties of Zr‐Substituted Bi0.9Gd0.1FeO3 Multiferroics
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Prakash Chandra Sati Manoj Kumar Sandeep Chhoker 《Journal of the American Ceramic Society》2015,98(6):1884-1890
Polycrystalline BiFeO3 (BFO) and Bi0.90Gd0.10Fe1?xZrxO3 (x = 0.0–0.10; BGFZx) ceramics were synthesized by solid‐state reaction method. Rietveld analysis of X‐ray diffraction patterns showed that BFO and BGFZx = 0.0 samples are stabilized in rhombohedral structure (space group R3c), whereas a small fraction of orthorhombic phase (space group Pn21a) is observed for BGFZx = 0.03–0.10 samples. Suppression and disappearance of some Raman modes indicated a structural phase transition with addition of Zr dopant at Fe site. Magnetic measurements exhibited weak ferromagnetic behavior of BGFZx samples with increasing Zr+4 concentrations. The insertion of Gd+3 ions at Bi+3 sites and nonmagnetic Zr+4 ions at Fe+3 sites in Fe–O–Fe network suppressed the spin cycloid structure of BFO which in turn enhanced the magnetization of these ceramics. Electron spin resonance spectra revealed the breaking of spin cycloid of BFO due to the development of free spins with addition of Zr+4 dopants at Fe sites. UV–Visible diffuse reflectance spectra showed one d–d crystal field transition and two charge‐transfer (C–T) transitions along with a sharp absorption of light in visible region for all samples. Almost frequency‐independent dielectric constant and dielectric loss along with very low values of dielectric loss indicated greatly improved dielectric properties for BGFZx = 0.03–0.10 samples. 相似文献
13.
Wenhan Dong Bi-Xia Wang Yi Yuan Hua Wu Alexei A. Bokov Zuo-Guang Ye 《Journal of the American Ceramic Society》2022,105(7):4775-4783
To explore lead-reduced dielectric materials in the SrTiO3–PbTiO3–PbZrO3 ternary system, a novel solid solution between relaxor ferroelectric (Pb0.5Sr0.5)(Zr0.5Ti0.5)O3 and ferroelectric PbTiO3, namely (1 − x)(Pb0.5Sr0.5) (Zr0.5Ti0.5)O3–xPbTiO3 (lead–strontium–zirconate–titanate [PSZT]–PT), has been synthesized in the perovskite structure by high-temperature solid-state reaction method in the form of ceramics. The crystal structure and phase symmetry of the materials synthesized were analyzed and resolved based on X-ray powder diffraction (XRD) data through both the Pawley and Rietveld refinements. The results of the structural refinements indicate that at low PT-concentration end of the solid solution system, for example, x = 0.05, the PSZT–PT solid solution exhibits a cubic structural symmetry (with the space group Pm-3m). As the PT concentration (x) increases, the structure of (1 − x)PSZT–xPT gradually transforms from the cubic to a tetragonal (P4mm) phase. In the composition range of x = 0.10–0.25, a mixture of the cubic and tetragonal phases was identified. As the concentration of PT increases, the proportion of the tetragonal phase increases at the expense of the cubic phase. For a composition of x > 0.25, a pure tetragonal phase is observed. The dielectric properties of the materials were studied by measuring the permittivity as a function of temperature at various frequencies. For the composition of x = 0.05, the temperature dependence of dielectric constant shows typical relaxor behavior. For x = 0.35, the dielectric peaks indicate a normal ferroelectric phase transition. Overall, a structural transformation from a central-symmetric, nonpolar cubic phase to a non-centrosymmetric, polar tetragonal phase is induced by the substitution of PT for PSZT in the pseudo-binary solid solution of (1 − x)PSZT–xPT, which also reveals an interesting relaxor to ferroelectric crossover phenomenon. 相似文献
14.
Yangchun Rong Jun Chen Huajun Kang Laijun Liu Liang Fang Longlong Fan Zhao Pan Xianran Xing 《Journal of the American Ceramic Society》2013,96(4):1035-1038
New binary system (1?x) PbTiO3?xBi(Ni1/2Zr1/2)O3 (PT–100x BNZ) with x ≤ 0.45 were synthesized via solid‐state reaction route. A morphotropic phase boundary (MPB) was identified around x = 0.40 by X‐ray diffraction (XRD) method. The ceramics with MPB composition exhibit enhanced ferroelectric properties. A large piezoelectric coefficient (d33) up to 400 pC/N was obtained for the PT–40BNZ, which is comparable with the PbTiO3–BiScO3 (PT–BS, 450 pC/N).The frequency dependence of dielectric permittivity of PT–40BNZ shows characteristic of a strong relaxor feature and a transition temperature around 290°C (1 MHz). Temperature effect on the unipolar strain was also investigated. The present system with high d33 is a competitive piezoelectric material, as no expensive oxide is used here compared with the PT–BS. 相似文献
15.
Longwen Wu Xiaohui Wang Zhengbo Shen Longtu Li 《Journal of the American Ceramic Society》2017,100(1):265-275
The (1?x)BaTiO3–xBi(Zn2/3Nb1/3)O3 (x = 0.01–0.30) ceramics were synthesized by solid‐state reactions. The solubility limit was determined to be x = 0.20. A systematic structural transition from a tetragonal phase (x ≤ 0.034), to a mixture of tetragonal and rhombohedral phases (0.038 ≤ x ≤ 0.20), and finally to a pseudocubic phase (x ≥ 0.22) at room temperature was identified. Dielectric measurement revealed a ferroelectric (x ≤ 0.04) to relaxor (x ≥ 0.06) transition with permittivity peak broadening and flattening, which was further verified by Raman spectroscopy and differential scanning calorimetry (DSC). Activation energies obtained from the Vogel–Fulcher model displayed an increasing trend from ~0.03 eV for x ~ 0.05, to unusually high values (>0.20 eV) for the compositions with x ≥ 0.15. With the increase in Bi(Zn2/3Nb1/3)O3 content, the polarization hysteresis demonstrated a tendency from high nonlinearity to sublinearity coupled with the reduction in remnant polarization and coervice field. The deconvolution of the irreversible/reversible polarization contribution was enabled by first‐order reversal curve distributions, which indicates that the decreasing polarization nonlinearity with the increase in Bi(Zn2/3Nb1/3)O3 concentration could be related with the change from the ferroelectric domain and domain wall contributions to the weakly coupled relaxor behaviors. 相似文献
16.
Yongxing Wei Xiaotao Wang Jintao Zhu Xiaoli Wang Jiangjiang Jia 《Journal of the American Ceramic Society》2013,96(10):3163-3168
Perovskite solid solution ceramics of (1 ? x)BiFeO3–xBaTiO3 (1 ? x)BF–xBT, 0.2 ≤ x ≤ 0.45) with high electrical resistivity were prepared by solid‐state reaction method. Actual ferroelectric hysteresis loops and temperature dependence of dielectric constant of the ceramics were obtained. Ceramics of 0.7BF–0.3BT with small rhombohedral distortion show highest remnant polarization (Pr = 26.0 μC/cm2) and piezoelectric coefficient (d33 = 134 pC/N). Compositions with pseudo‐cubic symmetry (intermediate phases) show relaxor‐like dielectric anomaly. The values of Pr and d33 decrease with increasing BT content, from 24.8 μC/cm2 and 104 pC/N for 0.65BF–0.35BT to 8.2 μC/cm2 and 5 pC/N for 0.55BF–0.45BT. 相似文献
17.
Structure‐property relationships in BiScO3–PbTiO3–PbMg1/3Nb2/3O3 ceramics near the morphotropic phase boundary
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Mikhail V. Talanov Alexander A. Bush Konstantin E. Кamentsev Vladimir P. Sirotinkin Andrei G. Segalla 《Journal of the American Ceramic Society》2018,101(2):683-693
The phase structure, dielectric, ferroelectric, and piezoelectric properties of (1?2x)BiScO3–xPbTiO3–xPbMg1/3Nb2/3O3 ceramics (x = 0.30‐0.46) were studied. It was found that an increase in x leads to a structural phase transition between the rhombohedral and tetragonal phase via an intermediate monoclinic phase and to a crossover from the nonergodic relaxor state to the ferroelectric one. It was proposed that at x > 0.42 the phase transition changes from second to first order. The assumption about the existence of a tricritical point on the phase diagram at x ≈ 0.42 with the enhanced dielectric response has been made. The observed structure‐property relationships of the studied solid solutions are discussed. It is shown that the solid solutions with x = 0.42 are characterized by the high piezoelectric parameters (d33 = 509 pC/N, d31 = ?178 pC/N, dh = 153 pC/N), which makes possible their applications in sonar equipment. 相似文献
18.
Satya Narayan Tripathy Karuna Kara Mishra Shrabanee Sen Dillip K. Pradhan 《Journal of the American Ceramic Society》2014,97(6):1846-1854
A series of lead‐free perovskite solid solutions of (1 ? x) Na0.5Bi0.5TiO3(NBT)—x BaSnO3(BSN), for 0.0 ≤ x ≤ 0.15 have been synthesized using a high‐temperature solid‐state reaction route. The phase transition behaviors are studied using dielectric and Raman spectroscopic techniques. The ferroelectric to relaxor phase transition temperature (TFR) and the temperature corresponding to maximum dielectric permittivity (Tm) are estimated from the temperature‐dependent dielectric data. Dielectric studies show diffuse phase transition around ~335°C in pure NBT and this transition temperature decreases with increase in x. The disappearance of x‐dependence of A1 mode frequency at ~134 cm?1 for x ≥ 0.1 is consistent with rhombohedral‐orthorhombic transition. In situ temperature dependence Raman spectroscopic studies show disappearance and discontinuous changes in the phonon mode frequencies across rhombohedral (x < 0.1)/orthorhombic (x ≥ 0.1) to tetragonal transition. 相似文献
19.
Cai‐Xia Li Bin Yang Shan‐Tao Zhang Rui Zhang Ye Sun Hong‐Jun Zhang Wen‐Wu Cao 《Journal of the American Ceramic Society》2014,97(3):816-825
The structures, Curie temperature, dielectric relaxor behaviors, ferroelectricity, ferromagnetism, and magnetocapacitance of the (1?x)Ba0.70Ca0.30TiO3–xBiFeO3 [(1?x)BCT–xBF, x = 0–0.90] solid solutions have been systematically investigated. The ceramics have coexisted tetragonal (T) and orthorhombic (O) phases when x ≤ 0.06, coexisted pseudocubic (PC) and O phases when x = 0.065, coexisted cubic and O phases when 0.07 ≤ x ≤ 0.12, PC phase when 0.21 ≤ x ≤ 0.42, coexisted T and rhombohedral (R) phases when 0.52 ≤ x ≤ 0.70, and R phase when x ≥ 0.75. Significantly, composition‐dependent microstructures and Curie temperature are observed, the average grain size increases from 1.9 μm for x = 0, reaches 12.0 μm for x = 0.67, and then decreases to 1.3 μm for x = 0.90. At room temperature, the ceramics with x = 0.42–0.70 show piezoelectric properties and multiferroic behaviors, characterized by the polarization‐electric field, polarization current intensity–electric field, and magnetization–magnetic field curves, the composition with x = 0.67 has maximum polarization, remnant polarization, maximum magnetization, and remnant magnetization of 15.0 μC/cm2, 9.1 μC/cm2, 0.33 emu/g, and 0.14 emu/g, respectively. In addition, the magnetocapacitance is evidenced by the increased relative dielectric constant with increasing the applied magnetic field (H). With ΔH = 8 kOe, the composition with x = 0.67 shows the largest values of (εr(H) ? εr(0))/εr(0) = 2.96% at room temperature. The structure–property relationship is discussed intensively. 相似文献
20.
Wanli Zhao Ruzhong Zuo Donggeng Zheng Longtu Li 《Journal of the American Ceramic Society》2014,97(6):1855-1860
The 0.45Bi(Mg0.5Ti0.5)O3–(0.55 ? x)PbTiO3–x(Bi0.5Na0.5)TiO3 (BMT–PT–xBNT) ternary solid solution ceramics were prepared via a conventional solid‐state reaction method; the evolution of dielectric relaxor behavior and the electrostrain features were investigated. The XRD and dielectric measurements showed that all studied compositions own a single pseudocubic perovskite structure and undergo a diffuse‐to‐relaxor phase transition owing to the evolution of the domain from a frozen state to a dynamic state. The formation of the above dielectric relaxor behavior was further confirmed by a couple of measurements such as polarization loops, polarization current density curves, as well as bipolar strain loops. A large strain value of ~0.41% at a driving field of 7 kV/mm (normalized strain d33* of ~590 pm/V) was obtained at room temperature for the composition with x = 0.32, which is located near the boundary between ergodic and nonergodic relaxor. Moreover, this electric field‐induced large strain was found to own a frequency‐insensitive characteristic. 相似文献