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Regulation of BaTiO3 ceramics’ electrical properties by varying Na0.5Bi0.5TiO3 dopants
Shuiyun Li,Mingyang Ma,Yongshang Tian,Ruobing Li,Xiongjie Hu,Peng Liu 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.4
The piezoelectricity of BaTiO3 (BT) ceramics could be effectively regulated by Na0.5Bi0.5TiO3 (NBT) compounds, and themechanism is still controversial. In this work, BT-xNBT ceramics with various NBT contents (x) were synthesized by aconventional solid-state sintering process. The characteristic of phase, cross-section morphology, permittivity, ferroelectricity,and piezoelectricity were fully explored by some advanced test equipment. With an increment of x, the ceramics possessed ahigh densification with a sole tetragonal phase, the diffused phase transition and relaxor ferroelectricity enhanced firstly andthen receded. The inherent ferroelectricity and large strain of NBT materials under an electric field were deemed as thereasons for the increased ferroelectricity and piezoelectric coefficients with excessive x, respectively. Moreover, influences ofimpurity phases, fine grains, internal stress, etc. on the electrical properties were also discussed. This work provides a novelstrategy to regulate BT-based lead-free piezoelectric ceramics.
Shuiyun Li,Yongshang Tian,Xiaoliang Dong,Peng Liu,Xiang Ji,Xiongjie Hu 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.5
Ceramic proppants is crucial in hydraulic fracturing for increasing oil and gas reservoirs. In this study, the ceramic particlesand resin-impregnated ceramic particles were prepared with fly ash, and then ultra-lightweight ceramic particles (proppants)were obtained by double resin-coating process. Crystalline phase and microstructure of the ceramic particles were investigatedby X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Effects of silicon carbide and epoxy resinconcentrations on the phase, apparent density, and breakage ratio of the ceramic particles were all studied systematically. Withincreasing silicon carbide contents, the corundum phase transform to mullite phase, decreasing the apparent density andincreasing the breakage ratios. The double resin-coated ceramic proppants featured smoother surface and less pores than theresin-impregnated samples, accompanying low apparent density (1.94 g/cm-3) and high strength (breakage ratio under 52 MPa,1.69%) when silicon carbide was 3.0 wt.% and epoxy resin concentrations was 55 wt.%. The results suggest the particles bythe effective double resin-coating process possess promising candidates for fracturing proppants in practical applications.
Yongshang Tian,Shuiyun Li,Bingqian Zhang,Yansheng Gong,Peng Liu,Xiongjie Hu,Qiangshan Jing 한양대학교 세라믹연구소 2022 Journal of Ceramic Processing Research Vol.23 No.4
The electrical properties of piezoelectric ceramics are temperature-dependent, which affects their potential for applications inenvironments with temperature variation. In this work, Yb3+ and Tm3+ co-doped Ba0.95Ca0.05Ti0.90Zr0.10O3 (BCTZ-YT) denselead-free ceramic was prepared using a modified polymeric precursor route. On the basis of structural and electricalmeasurements at various temperatures, the mechanism of a lack of oxygen vacancies, small structural defects, and small defectdipoles was deduced. This study reveals that the ferroelectricity and piezoelectricity are temperature-dependent, whereas thecapacitance is essentially unchanged with increasing temperature owing to the presence of a pure orthorhombic phase. Thecapacitance of the BCTZ-YT ceramic was essentially constant at ~4.5 nF, the thermal expansion coefficient was 8.57 × 10−6 K−1below 75 oC, and the piezoelectric response (d33*) was above 416 pm/V in a wide temperature range (-20 to 40 oC), suggestingthe results of this study are expected to inform future research.