Crystal structure, dielectric and piezoelectric properties of Ta/W codoped Bi3TiNbO9 Aurivillius phase ceramics

Zhihang Peng,Dongxu Yan,Qiang Chen,Deqiong Xin,Dan Liu,Dingquan Xiao,Jian-guo Zhu 한국물리학회 2014 Current Applied Physics Vol.14 No.12

Aurivillius phase Bi3Ti1xTaxNb1xWxO12 high temperature piezoceramics were prepared by a conventional solid state reaction method. The crystal structure, dielectric, electrical conduction and piezoelectric properties were systematically studied. Pure or modified Bi3TiNbO9 ceramics revealed the presence of only two-layered Aurivillius phase, indicating that Ta/W doping entered into the B-site of pseudo-perovskite structure and formed solid solutions. The Curie temperature had a strong reliance on the structural distortion. Furthermore, Ta/W dopants act as a donor doping, decrease the number of oxygen vacancies and facilitate the domain wall motion. As a result, Ta/W modifications significantly increase the DC resistivity and piezoelectric properties. Bi3Ti0.98Ta0.02Nb0.98W0.02O12 ceramics possess the optimum d33 value (~12.5 pC/N) together with a high TC point (~893 C). Moreover, the resonance eantiresonance spectra demonstrate that the Ta/W-BTN ceramics are indeed piezoelectric in nature at 600 C. The d33 value of BTTNW-2 ceramic remains ~12.2 pC/N after annealing at 700 C. These factors suggest that the BTTNW-based ceramic is a promising candidate for ultra-high temperature sensor applications.

Evolution of microstructure and dielectric properties of (LiCe)-doped Na0.5Bi2.5Nb2O9 Aurivillius type ceramics

Zhihang Peng,Qiang Chen,Dan Liu,Yadan Wang,Dinquan Xiao,Jian-guo Zhu 한국물리학회 2013 Current Applied Physics Vol.13 No.7

Aurivillius type (NaBi)0.5x(LiCe)xBi2Nb2O9 ceramics were prepared by the standard ceramics route. The single crystal structural ceramics were achieved for all compositions and lattice distortion was decreased by (LiCe) dopants. The temperature dependent dielectric properties revealed that all compositions possess a high Curie-temperature (>780 ℃). A modified CurieeWeiss relationship is used to study the diffuseness behavior of a ferroelectric phase transition indicating the degree of diffuseness of NBN-based ceramics increased with (LiCe) modifications. The degradation of resistance implied a plausible model that Ce4þ ions entered into the B-site of the pseudo-perovskite structure and acted as acceptor doping. Further investigation demonstrated that both electrical conduction and dielectric relaxation processes were associated with the oxygen vacancies produced by the substitution of Nb5+ ions by the Ce4+ ions.

Damage-control technology of oil-based drilling fluid for Kuqa piedmont structure

Peng Xu,Zhengwu Tao,Xiao Liu,Zhihang Yan,Mingbiao Xu 한국자원공학회 2018 Geosystem engineering Vol.21 No.1

Oil-based drilling fluid is widely used in tight sandstone well and shale well in recent years, performance advantages of borehole stability and formation protection are the main reason to promote its use. According to the development and existing research, oil-based drilling fluid still existed serious damage, and could not catch the attention of developers. The study chose Keshen Block as the research object, analyzed reservoir characteristics, evaluated rock wettability, damage of oil-based drilling fluid and oil trapping, and analyzed damage mechanisms of oil-based drilling fluid. Based on the damage mechanisms and the characteristics of drilling fluid, the study analyzed the damage-control mechanisms, established optimization principle of oil-based drilling fluid, and optimized drilling fluid. Dynamic damage experiments and field application of drilling fluid showed that formation protection performance of optimized oil-based drilling fluid had improved significantly, and the formation damage caused by oil-based drilling fluid had been controlled effectively.

The effects of oxygen vacancies on the electrical properties of W, Ti doped CaBi2Nb2O9 piezoceramics

Xinghe Xing,Feng Cao,Zhihang Peng,Yang Xiang 한국물리학회 2018 Current Applied Physics Vol.18 No.10

Different type doped CaBi2Nb2O9 (CBN) ceramics were prepared by a conventional solid state sintering method. The number of oxygen vacancies were decreased or increased by the introduction of W6+ and Ti4+ doping in CBN ceramics. The influence of W6+, Ti4+ and W6+/Ti4+ dopants on the microstructures and electrical properties of CBN-based ceramics was investigated. The voids and spherical morphology in the SEM image of W, Ti co-doped ceramics indicate that W, Ti co-doping could change the microstructure of CBN-based ceramics. Impedance analysis results show that the electrical properties of CBN-based ceramics have a close relationship with the number of oxygen vacancies. W doping and W, Ti co-doping decrease the oxygen vacancies, as a result, the resistance and piezoelectric properties were increased and the frequency dispersion of dielectric properties were restrained.

(Ba, Ca)(Ti, Zr)O3-BiFeO3 lead-free piezoelectric ceramics

Jiagang Wu,Wenjuan Wu,Dingquan Xiao,John Wang,Zhenchun Yang,Zhihang Peng,Qiang Chen,Jianguo Zhu 한국물리학회 2012 Current Applied Physics Vol.12 No.2

Effects of BiFeO3 (BFO) content on the microstructure and electrical properties of Ba0.85Ca0.15Ti0.90Zr0.10O3(BCTZ) ceramics prepared by normal sintering in air were investigated. A stable solid solution is formed between BCTZ and BFO. The grain size gradually becomes smaller, and the ceramics become denser with increasing the BFO content. The Curie temperature, dielectric constant, and dielectric loss of BCTZ ceramics decrease simultaneously with the introduction of BFO. Moreover, the remanent polarization reaches a maximum at x ¼ 0.2 mol%, and the coercive field continuously increases with increasing the BFO content due to the introduction of BFO with a higher coercive field. Improved piezoelectric properties (d33 w 405 pC/N and kp w 0.44) are demonstrated for the BCTZ ceramic with x ¼ 0.2 mol%.

Colchicine-induced tetraploidy inflfl uences morphological and cytological characteristics and enhances accumulation of anthocyanins in a red-flfl eshed radish (Raphanus sativus L.)

Fabo Chen,Jian Gao,Wenbo Li,Yi Liu,Ping Fang,Zhihang Peng 한국원예학회 2021 Horticulture, Environment, and Biotechnology Vol.62 No.6

Red-fl eshed radishes (RFRs) are economically important root vegetable in the Brassicaceae family that contain high concentrationsof radish-red pigment in their fl eshy root. However, the yield of the fl eshy root is limited and germplasm resourcesfor radish improvement are lacking. Genome doubling is an eff ective and effi cient breeding tool for the rapid creation ofnew germplasm resources. Therefore, we aimed to induce tetraploidy in RFRs to improve pigment production. RFR seedswere immersed in aqueous colchicine (0, 0.01, 0.05, 0.10, 0.15, and 0.20% (w/v)) for 24 h followed by cultivation at 25 for 7 days, and those with uniform and distinctly swelled and short hypocotyls were selected as putative tetraploids. Theputative tetraploids were identifi ed by fl ow cytometry, and then we further examined the morphological and cytologicalcharacteristics of the diploid and tetraploid plants and measured gene expression via reverse transcription quantitative PCR. The results indicated that the most suitable concentration of colchicine (0.05% (w/v)) could induce tetraploidy in RFRs, witha tetraploid-induction rate as high as 34.50%. In addition, tetraploids exhibited a “gigantism” eff ect in both morphologicaland cytological traits, including swelled hypocotyls, thicker cotyledons, larger stoma, wider and longer leaves, taller plants,larger fl owers, increased pollen size, larger seed pods and seeds, and a larger taproot. Moreover, compared with diploid plants,the pigment content and yield of pigment per plant of tetraploid plants were increased by 65.11% and 216.82%, respectively. Therefore, we present a simple and effi cient method for tetraploid induction via soaking radish seeds in 0.05% (w/v) colchicinefor 24 h. The results showed that tetraploid plants not only exhibited obvious “gigantism” eff ects but also signifi cantlyenhanced accumulation of anthocyanins, and represent a practical breeding material for improving pigment yield in RFRs.