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8. Structure and relaxor ferroelectric behavior of novel tungsten bronze type ceramic, Sr5BiTi3Nb7O30

Author

He, Qiuwei, Schmid, Siegbert, Chen, Xue, Peng, Biaolin, Li, ChunChun, Hu, Changzheng, Liu, Laijun, and Hinterstein, Manuel

Subjects
Condensed Matter - Materials Science
Abstract

A novel lead-free tungsten bronze type ceramic Sr5BiTi3Nb7O30, was prepared by a conventional solid-state reaction route. The room-temperature crystal structure shows an average structure with centro-symmetric space group P4/mbm identified by synchrotron XRD. Temperature dependence of dielectric permittivity indicates that Sr5BiTi3Nb7O30 is a ferroelectric relaxor with Tm near 260 K. The ceramic displays stronger frequency dispersion and lower phase-transition temperature compared with Sr6Ti2Nb8O30. A macroscopic and phenomenological statistical model was employed to describe the temperature dependence of their dielectric responses. The calculated size of polar nanoregions (PNRs) of Sr5BiTi3Nb7O30 compared with Sr6Ti2Nb8O30 implies that the stronger diffusion phase transition for the former is related to the disorder emerged in both A and B sites. The smaller PNRs can be activated at lower temperature but have smaller electrical dipole moment. This is the origin of relaxor behavior of Sr5BiTi3Nb7O30 with lower Tm and dielectric permittivity. The PNRs is related to a local structure with a polar space group P4bm, which contributes to the dielectric frequency dispersion of relaxor behavior. This work opens up a promising feasible route to the development of relaxor ferroelectrics in tungsten bronze type oxides., Comment: 21 pages, 9 figures

Published
2022
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23. Dynamic behavior of polar nanoregions in re-entrant relaxor 0.6Bi(Mg1/2Ti1/2)O3-0.4PbTiO3

Author

Chen, Kaiyuan, Zhang, Qi, Liu, Jia, Wang, Jie, Lan, Zhencheng, Fang, Liang, Hu, Changzheng, Luo, Nengneng, Peng, Biaolin, Long, Changbai, Wang, Dawei, and Liu, Laijun

Subjects
Condensed Matter - Materials Science
Abstract

The existence of polar nanoregions is the most important characteristic of ferroelectric relaxors, however, the size determination and dynamic of PNRs remains uncertain. We reveal a re-entrant relaxor behavior and ferroelectric-paraelectric transition coexists in complex perovskite oxide 0.6Bi(Mg1/2Ti1/2)O3-0.4PbTiO3. Two dielectric anomalies (i) the low-temperature re-entrant relaxor transition and (ii) the high-temperature diffuse phase transition (DPT) were described by the phenomenological statistical model. The sizes of the two kinds of polar nanoregions (PNRs) corresponding to two ferroelectric states were obtained. The dynamic of PNRs were analyzed using isothermal electrical modulus, which shows three critical temperatures associated with the diffuse phase transition, the formation and freezing of PNRs, respectively. The temperature evolution of the PNRs evolution depends on the stoichiometry of bismuth. The results provide new insights into the dynamic behavior of PNRs and the modification way of re-entrant relaxor behavior., Comment: 29 pages, 9 figures, 4 tables

Published
2020

25. Phase evolution and thermal stability of high Curie temperature BiScO$_3$-PbTiO$_3$-Pb(Cd${1/3}$Nb$_{2/3}$)O$_3$ ceramics near MPB

Author

Lan, Zhencheng, Chen, Kaiyuan, He, Xiafeng, Zhou, Shuo, Zheng, Xiande, Liu, Jia, Fang, Liang, Lei, Xiuyun, Wang, Dawei, Peng, Biaolin, and Liu, Laijun

Subjects
Condensed Matter - Materials Science
Abstract

Piezoelectric and ferroelectric ceramics with a high Curie temperature (Tc) have attracted a growing attention owning to their applications under severe environments. In this work, phase structure, dielectric, ferroelectric and piezoelectric properties of (0.975-x)BiScO3-xPbTiO3-0.025Pb(Cd1/3Nb2/3)O3 ceramics (x = 0.58-0.64) were studied. A composition-induced structural transformation occurs from rhombohedral phase to tetragonal phase through an intermediate monoclinic phase with the increasing PT concentration. The relationship between structure and electrical properties of the system were discussed. The BS-xPT-PCN system near the morphotropic phase boundary (x = 0.62) exhibits excellent piezoelectric and ferroelectric performances with d33 = 508 pC/N, kp = 56%, and Pr = 40 uC/cm2. The high-temperature piezoelectricity of the sample with MPB (x = 0.62) was characterized by an in situ XRD. The excellent thermal stability of the crystal structure and the piezoelectric property indicate that the BS-xPT-PCN system is a promising candidate for high temperature piezoelectric applications., Comment: 28 pages, 10 figures

Published
2019
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32. Localized polarons and conductive charge carriers: understanding CaCu$_{3}$Ti$_{4}$O$_{12}$ over a broad temperature range

Author

Liu, Laijun, Ren, Shaokai, Liu, Jia, Han, Feifei, Zhang, Jie, Peng, Biaolin, Wang, Dawei, Bokov, Alexei A., and Ye, Zuo-Guang

Subjects
Condensed Matter - Materials Science
Abstract

CaCu$_{3}$Ti$_{4}$O$_{12}$ (CCTO) has a large dielectric permittivity that is independent of the probing frequency near the room temperature, which complicated due to the existence of several dynamic processes. Here, we consider the combined effects of localized charge carriers (polarons) and thermally activated charge carriers using a recently proposed statistical model to fit and understand the permittivity of CCTO measured at different frequencies over the whole temperature range accessible by our experiments. We found that the small permittivity at the lowest temperature is related to polaron frozen, while at higher temperatures the rapid increase is associated with the thermal excitation of polarons inducing the Maxwell-Wagner effect, and the final increase of the permittivity is attributed to the thermally activated conductivity. Such analysis enables us to separate the contributions from localized polarons and conductive charge carriers and quantify their activation energies.

Published
2018
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40. Electrical Quantum Coupling of Subsurface-Nanolayer Quasipolarons.

Author

Zeng, Yihan, Li, Ruichen, Fang, Shengyu, Hu, Yuting, Yang, Hongxin, Chen, Junhao, Su, Xin, Chen, Kai, and Liu, Laijun

Subjects
BISMUTH iron oxide, ELECTRIC impedance, DIELECTRICS, PERMITTIVITY, PHYSICS
Abstract

We perform dielectric and impedance spectrums on the compressively-strained ceramics of multiferroic bismuth ferrite. The subsurface-nanolayer quasipolarons manifest the step-like characteristic of pressure-dependent transient frequency and, furthermore, pressure-dependency fails in the transformation between complex permittivity and electrical impedance, which is well-known in classic dielectric physics, as well as the bulk dipole chain at the end of the dissipation peak. [ABSTRACT FROM AUTHOR]

Published
2024
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41. Phase structure and electrical properties of (Ba1/2Sr1/2)2+ modified high Curie temperature CaBi2Nb2O9‐based ceramics.

Author

Quan, Liming, Zhang, Biao, Chen, Kaiyuan, Meng, Yingzhi, Li, Wangxin, Long, Changbai, Fang, Liang, Peng, Biaolin, Chen, Xue, Wang, Dingyuan, Bai, Yisong, da Silva, Lucas Lemos, and Liu, Laijun

Subjects
CURIE temperature, PIEZOELECTRIC ceramics, HIGH temperatures, STRONTIUM, CERAMICS, RIETVELD refinement, ALKALINE earth metals, RAMAN spectroscopy
Abstract

High‐temperature piezoelectric sensing is usually used in the aerospace, automotive, and power plant fields. High temperature piezoelectric ceramics are considered the key materials in these fields. In this paper, Ca1−x(Ba1/2Sr1/2)xBi2Nb1.985(W3/4Mn1/4)0.015O9 (x = 0.05, 0.10, 0.15 and 0.20) (C1−xBSxBNWM) has been synthesized by a traditional solid state reaction method. The effects of substitution of calcium at the A‐site by barium and strontium on phase evolution and piezoelectric properties of the CaBi2Nb2O9 orthorhombic Aurivillius phases were investigated. The crystal structure of piezoelectric ceramics was characterized by XRD, Rietveld refinement, and Raman spectroscopy. Co‐substitution of barium/strontium (Ba2+/Sr2+) and tungsten/manganese (W6+/Mn4+) resulted in lattice distortion of C1−xBSxBNWM ceramics. The results induce that the tetragonal crystal structure increase with increasing the co‐substitution cations. Isothermal impedance spectroscopy confirmed intrinsic thermally activated conduction in the system. The C1−xBSxBNWM ceramics with x = 0.15 exhibit a very high Curie temperature (TC ∼ 923°C), a reasonable piezoelectric coefficient (d33 = 13.3 pC/N). Remarkably, even after thermal annealing at temperatures up to 800°C, it still retains a high d33 of 13 pC/N. In addition, the C0.85BS0.15BNWM ceramic had a relatively high resistivity (3.82 × 106 Ω·cm, 500°C). The Ca0.85(Ba1/2Sr1/2)0.15Bi2Nb1.985(W3/4Mn1/4)0.015O9 ceramics make possible their application in high‐temperature acceleration transducers. [ABSTRACT FROM AUTHOR]

Published
2024
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42. Processing strategy and composite regulation on dielectric performance in Li2O–Al2O3–B2O3 dielectric systems using SrTiO3.

Author

Xiong, Siyu, Chen, Deqin, Zhu, Xiaowei, Zhu, Guobin, Xiao, Hongxiang, Gong, Weiping, Liu, Laijun, Khaliq, Jibran, and Li, Chunchun

Subjects
IONIC conductivity, PERMITTIVITY, DIELECTRIC properties, DIELECTRICS, SPECIFIC gravity, QUALITY factor
Abstract

In this paper, we investigated the effect of processing parameters and composite regulation on the structure and property relationship of lightweight low‐permittivity Li2O–Al2O3–B2O3 dielectric system. Li2BAlO4 ceramic and (1 − x)Li2BAlO4–xSrTiO3 ceramics were synthesized using a conventional solid‐state reaction method. Thermodynamic analysis, sintering temperature, phase formation, crystal structure, and microwave dielectric properties were investigated. Thermal analysis revealed a melting temperature of 847°C, suggesting a comparatively low temperature for the sintering of Li2BAlO4 ceramics. Li2BAlO4 crystalized into a monoclinic structure with P21/c space group, with [Al2B2O8] rings connected by [BO3] triangles and [AlO4] tetrahedra through Al–O–Al bridges. Dense Li2BAlO4 ceramics with a relative density of ∼97.7% were sintered at 750°C and had optimal microwave dielectric properties with relative permittivity (εr) of 5.13, quality factor (Q × f) of 22 610 GHz, and the temperature coefficient of resonance frequency (τf) of −112.5 ppm/°C. The 0.88Li2BAlO4–0.12SrTiO3 composite ceramic has excellent microwave dielectric properties with εr = 8.83, Q × f = 14 000 GHz, τf = 4.6 ppm/°C. The ceramics also demonstrated an inert behavior with silver electrodes proving its application in low‐temperature cofired ceramic (LTCC) technology. [ABSTRACT FROM AUTHOR]

Published
2024
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