|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | First-order phase transition and unexpected rigid rotation mode in hybrid improper ferroelectric(La,Al)co-substituted Ca_(3)Ti_(2)O_(7) ceramics显示文摘Ca_(3)Ti_(2)O_(7) with Ruddlesden-Popper structure exhibits the largest polarization among the known hybrid improper ferroelectrics.However,the high Curie temperature impedes the thorough study of phase transition through dielectric characterization.According to the previous theoretical design rule,the Curie temperature can be suppressed by increasing the tolerance factor.So,in the present work,high-quality Ca_(3-x)LaxTi_(2-x)Al_(x)O_(7)(x=0.0,0.1,0.2,0.3)ceramics with increased tolerance factors were successfully prepared.The amplitude of oxygen octahedral tilt mode indeed decreases with increasing tolerance factors,leading to a degeneration of ferroelectric polarization.However,the unexpected rigid rotation mode causes the composition-invariable coercive fields.The Curie temperatures decrease linearly with increasing x and tolerance factors.The variable-temperature dielectric constant confirms first-order improper ferroelectric transitions in Ca_(3)Ti_(2)O_(7)-based ceramics.The results of variable temperature Xray diffraction reveal the coexistence of two-phases below Curie temperature.The present work confidently confirms the first-order improper ferroelectric transition in Ca_(3)Ti_(2)O_(7)-based ceramics by combining results of variable-temperature dielectric response and in-situ X-ray powder diffraction. | Z.Z.Hu J.J.Lu B.H.Chen T.T.Gao X.Q.Liu W.Wen X.M.Chen | 2019 | Journal of Materiomics2019，5，4： | 4 |
| 2 | Gomplex-permittivity Measurement on High-Q Materials Via Combined Numerical Approaches显示文摘 | X.C.Fan X.M.Chen X.Q.Liu | | 0，，10： | 1 |
| 3 | Structure and Microwave Dielectric Characteristics of Ca1-x-xNd2x/3 TiO3 Ceramics显示文摘 | M.S.Fu X.Q.Liu X.M.Chen | | 0，，03： | 1 |
| 4 | High permittivity and low loss dielectric ceramics in the BaO-La2O3-TiO2-Ta2O5 system显示文摘 | X.M.Chen Y.H.Sun X.H.Zheng | | 0，，23： | 1 |
| 5 | Dielectric Characteristics of Ceramics in BaO-Nd2O3-TiO2-Ta2O5 system显示文摘 | X.M.Chen J.S.Yang | | 0，，06： | 1 |
| 6 | EFFECTS OF ORDERING DOMAIN STRUCTURE ON DIELECTRIC PROPERTIES OF DOUBLE PEROVSKITE La_(2)NiMnO_(6)显示文摘Two sets of La_(2)NiMnO_(6)ceramics with different B-site ordering degree were prepared and evaluated.The valence states of Ni^(2+)and Mn^(4+)were con-rmed,and the B-site ordering degree was estimated qualitatively using magnetic and Raman analysis.The ordering of Ni^(2+)and Mn^(4+)was the primary origin for the relaxor-like behavior of the present ceramics.The ordering degree of B-site ions greatly affected the dielectric properties,i.e.,more ordered sample indicated higher dielectric constant.Meanwhile,the grain boundary layer capacitor(GBLC)effect was also activated but limited at the high temperatures and low frequencies. | Y.Q.LIN S.Y.WU X.M.CHEN | 2011 | Journal of Advanced Dielectrics2011，1，3： | 0 |
| 7 | Room-temperature ferroelectricity in A-site ordered Ruddlesden-Popper Li_(2)CaTa_(2)O_(7) ceramics显示文摘In the present work,the crystal structure,ferroelectric and dielectric properties of the dense single-phase Li_(2)CaTa_(2)O_(7) ceramics with A-site ordered double-layer Ruddlesden-Popper structures have been investigated by the experiments and first-principles calculations.A polar Pna21 phase was determined by the Rietveld refinement against the X-ray diffraction pattern at room temperature,and it was confirmed by its lowest calculated energy and rigid phonon modes.The ferroelectricity was found by observing the ferroelectric hysteresis loop at room temperature,and its remanent polarization was similar to the value calculated from the Berry phase and Born effective charge approaches.The ferroelectricity is a nonconventional proper one since its polarization is induced from the displacement of oxygen anions instead of tantalum cations based on the individual atomic polarization.A first-order transition from an antiferroelectric to paraelectric phase around 900 K was found by the DSC and variable-temperature dielectric measurements.From the present work,the room-temperature ferroelectricity is experimental confirmed in the present ceramics,inspiring the search for new ferroelectricity in the ceramics with A-site ordered Ruddlesden-Popper structures. | B.H.Zhang Z.Z.Hu B.H.Chen X.Q.Liu X.M.Chen | 2020 | Journal of Materiomics2020，6，3： | 0 |
| 8 | Micro—structural analysis of YBa2Cu3O7—x thin films grown on different substrates by X—ray techniques显示文摘YBa2Cu3Ox(YBCO) thin films grown on different substrates with and/or without Eu2CuO4(ECO) buffer layer were investigated by X-ray wide angle diffraction,reflection,diffuse scattering and topography.Theresults show that for the yttria stabilized ZrO2(YSZ) substrate,the presence of an ECO buffer layer improves the crystalline quality of the YBCO film,while a negative effect is observed for the SrTiO3(STO) substrate.The lateral correlation length for a sample grown on a YSZ substrate with ECO buffer Layer is much greater than grown on an STO subetrate.The STO substrate used has mosaic structure.2001 Elsevier Science B.V.All rights reserved. | C.X.Liu M.Xu W.H.Tang X.M.Chen L.S.Wu N.Yang Z.H.Mai K.Tao J.G | 2001 | Beijing Synchrotron Radiation Facility2001，，2： | 0 |
| 9 | Enhanced ferroelectric and piezoelectric characteristics in Ca-substituted BaTi_(0.88)Zr_(0.12)O_(3)ceramics显示文摘In this work,Ba1−xCaxTi_(0.88)Zr_(0.12)O_(3)(x=0.00-0.25)ceramics were prepared by a solid-state reaction method,and the variation of dielectric,ferroelectric and piezoelectric characteristics has been investigated together with the structure evolution.The crystal structure varies from rhombohedral to tetragonal at room-temperature and the morphotropic phase boundary(MPB)is determined around x=0.10,where the significantly enhanced ferroelectric and piezoelectric properties are achieved.With the increase of Ca content,the system gradually evolves into a relaxor ferroelectric.This work provides useful guidance for future research on lead-free piezoelectric materials. | S.B.Chen S.Y.Wu X.M.Chen | 2022 | Journal of Advanced Dielectrics2022，12，3： | 0 |
| 10 | 双相钢和低合金高强度钢在液压成形技术中的应用显示文摘双相高强钢(DP)已经广泛应用于欧洲和日本的汽车零部件,最近又引起北美汽车制造业者的极大重视,将它用于改善汽车的冲撞性能和减轻汽车重量,与具有相近的初始屈服强度的低合金高强度钢(HSLA)相比,DP钢具有以下优点:更高的加工硬化能力,能量吸收能力,抗疲劳强度和烘硬化能力,并且无屈服点延伸,本文比较了DP钢和HSLA钢在液压形成过程前,过程中,过程后的行为特征,计算机模拟结果显示,DP钢在液压成形过程中具有更均匀的材料流变,更好地抗击性能和较小的起皱倾向。 | X.M.Chen 温宏权 | 2002 | 世界钢铁2002，2，3： | 0 |
| 11 | 小麦条锈病小种抗性基因鉴定显示文摘利用了8个北美的条锈菌小种.在北美小麦不同条锈病鉴别寄主之间以及它们与已知抗性基因的小麦品种进行杂交.并对亲本、F_1、F_2和一些回交子代的幼苗抗条锈性进行了评价。结果.中国166、HeinesⅦ、Fielder、Lee、Riebese147/51和Moro分别含有Yr1、Yr2、Yr6、Yr7、Yr9和Yr10抗性基因;Lemhi、Tyee中的一个基因.HeinesⅦ、Moro、Druchamp、Stephens、Lee和Fielder两个基因之一与命名的Yr基因和其它以前描述的基因不同。Lembi中的基因可能与Riebese147/51或Druchamp和Stephens其中之一基因等位或紧密连锁。HeniesⅦ中的1个基因与Cappelle Despresz、Nord Desprez和Stephens中的基因等位或紧密连锁。Druchamp、Stephens和Yamhill有Yr3a或Yr4a.Durchamp与Stephens有1个相同基因.但与Yamhill不同。Yamhill(HeinesⅦ/ALba)有来自HeniesⅦ的Yr2和来自Alba的2个基因。其中之一不是Yr7.可能与Paha中的1个基因相同或紧密连锁。Lenhi中的Yr1、Yr7、Yr9和Y10基因和Paha中的1个基因都是显性。Lee中的第二个基因和Paha中的1个基因可能是隐性等位基因。Tyee中的Yr2、Yr6、Yr3a或Yr4a基因与Stephens、Druchamp或Fielder中两个基因之一依赖于小种和亲本(遗传背景)的不同.在杂交中表现为隐性或显性。中国166中的Yrl、Riebese147/51中的Yr9、Lemhi和Tyee中的基因是独立的。 | X.M.Chen 万安民 | 1993 | 国外农学(麦类作物)1993，，6： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员