CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Dan Xu,Wenjie Zhao,Wenping Cao,Weili Li,Weidong Fei
The lead-free BiFe 1- x (Li 0·5 Nb 0.5 ) x O 3 ceramics with x = 0.00, 0.01, 0.02, 0.04, 0.06, and 0.08 were modified by Li/Nb co-doping. X-ray diffraction measurements indicated that all the ceramics had a rhombohedral distorted perovskite structure and secondary phases appeared when x = 0.00, 0.04, and 0.06. The BiFeO 3 ceramics with a small amount of Li/Nb co-doping exhibited improvements in the remnant polarization (2 P r ) and ferroelectric P - E loop shape compared with the results of pure BiFeO 3 (BFO). The decreased dielectric loss and leakage current indicated that proper Li/Nb co-doping for the Fe-site in BFO was a promising route to improve the leakage behavior and enhance the resistivity. These improved electrical properties were related to the reduction of oxygen vacancies and suppression of the formation of Fe 2+ . The leakage mechanism was also discussed and analyzed.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2023
·
IF 3.9
Lu Liu,Xiao Li Zhu,Xiang Ming Chen
In the present work, the strategy of multielements co-substitution for BiFeO 3 ceramics was adopted to enhance the ferroelectricity and magnetoelectric coupling effect where the effective radius of rare-earth ions was equivalent to that of Sm 3+ . Differing from the case of Sm-substituted BiFeO 3 ceramics, the symmetry of the present ceramics changed from R3c to Pbnm directly without the formation of Pna 2 1 with increasing RE-substitution content. The ferroelectricity was significantly improved, and the saturated polarization−electric field ( P - E ) hysteresis loop with P r = 37.63 μC/cm 2 was obtained in Bi 0.95 (La 0.20 Nd 0.20 Sm 0.20 Gd 0.20 Lu 0.20 ) 0.05 FeO 3 ceramics. The leakage current was reduced by almost six orders of magnitude in multielements co-substituted BiFeO 3 ceramics, which was much lower than that of BiFeO 3 end-member. Moreover, the magnetoelectric coupling coefficient α ME of 0.96 mV/cm Oe was achieved in Bi 0.86 (La 0.20 Nd 0.20 Sm 0.20 Gd 0.20 Lu 0.20 ) 0.14 FeO 3 ceramics, which was larger than that of Sm-substituted BiFeO 3 ceramics. The strategy of multielements co-substitution might provide a new approach to improving ferroelectricity and magnetoelectric coupling effect in BiFeO 3 ceramics, which could be physically interpreted as the results of the reduced leakage current and increased local polarization configuration caused by the multiple elements substitution.
研究领域:
材料科学
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物理学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Ting Wang,X.-L. Wang,S.-H. Song,Qing Ma
Multiferroic Nd/Sm-doped BiFeO 3 ceramics synthesized at 700 °C by spark plasma sintering in conjunction with sol-gel precursor powders are investigated by X-ray diffraction, scanning electron microscopy, dielectric , ferroelectric and magnetic measurements. With the doping content of Nd/Sm beyond 10 mol%, the crystal structure changes from R 3 c to coexistence of Pbam and R 3 c . It is also revealed that the grain size for all samples greatly decreases and the dielectric, ferroelectric and magnetic properties are obviously improved with Nd/Sm doping. The optimized remanent polarization are about 1.451 μC/cm 2 and 3.448 μC/cm 2 for the 10 mol% Nd-doped and 15 mol% Sm-doped BiFeO 3 ceramics, respectively. Because of the reduced concentration of oxygen vacancies , the leakage current density of Nd/Sm-doped ceramics decreases more than two orders of magnitude compared to the pure BiFeO 3 sample. The maximum remanent magnetization for the Sm-doped ceramics is approximately 0.279 emu/g, which is higher than that for the Nd-doped samples (0.263 emu/g).
研究领域:
材料科学
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凝聚态物理
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2015
·Vol. 41
·期 4
·5498-5504
·
IF 2.605
Shizhou Pu,He Zheng,Zhenlian Chen,Meiya Li,Zhongqiang Hu,Jianbo Wang,Huamin Zou
The microstructures of Bi 0.85 Nd 0.15 FeO 3 ceramics were investigated by using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), convergent-beam electron diffraction (CBED) and X-ray energy dispersive spectrometry (EDS). The superstructure phase related to 1/4( hh 0) p and 1/4(00 l ) p diffraction spots were observed in the samples. It is found that the superstructure phase can co-exist with R 3 c phase in a single grain. The bright and dark field images accompanied with SAED patterns provided evidences of the superstructure phase dispersed into the matrix with R3c symmetry and evolution of the domain. The ferroelectric domain wall was observed according to the displacement of Fe 3+ ions respect to Bi 3+ sub-lattice in the ferroelectric R 3 c phase based on HRTEM observations. The space group Pnam of the superstructure was identified by combining SAED and CBED techniques . EDS measurement revealed that the concentration of Nd in the Pnam phase is higher than that in R 3 c phase. This might mean that the transition from R 3 c to Pnam structure is due to the inhomogeneous distribution of the Nd concentration and the weakened stereochemical activity of Bi 3+ lone electron pair, arisen from the increase in Nd content.
研究领域:
材料科学
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凝聚态物理
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功能陶瓷
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电子显微学
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铁电材料
·
多铁材料
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2020
·Vol. 31
·期 11
·8464-8471
·
IF 2.22
Si Shufang,Deng Hongmei,Wang Tiantian,Yang Pingxiong,Chu Junhao
Perovskite compounds Bi 0.7 A 0.3 FeO 3−δ (BAFO) (A = Ca, Sr, Pb, and Ba) with improved optical and magnetic properties have been synthesized by solid-state method. The effect of bivalent ions substitution on the phase transition, microstructure, optical, and magnetic properties are investigated in detail. X-ray diffraction and Raman scattering spectra analyses indicate the phase transition from rhombohedral to cubic in doped samples and the coexistence of the two phases in BBFO, inducing strong lattice distortions. A blue shift observed in d–d transitions energies can reveal the decreased internal chemical pressure, thus leading to the slight increase in bandgaps of BSFO, BPFO, and BBFO. While, narrowed bandgap of 1.96 eV can be found in BCFO for the increased tailing of the conduction band edge into the gap. Besides, room-temperature ferromagnetism has been observed in Sr-, Pb-, and Ba-doped samples which can be resulted from the suppression of spiral structure of BFO. These results lay a solid foundation on further exploring the potential abilities of BFO ceramics as multiferroic photovoltaic materials.
研究领域:
材料科学
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固体物理
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光电
·
磁学
✓ 已验证
产品关联
DOI
高影响因子
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