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61.
62.
采用传统电子陶瓷工艺,制备了多重离子A位复合的、具有钙钛矿结构的新型压电陶瓷材料[(Na0.97-xkxLi0.03)0.5Bi0.5]TiO3(其中x为0.10,0.15,0.20和0.25),研究了该陶瓷的相结构与介电铁电性能。结果表明,随着K+含量的增加,材料的晶粒尺寸明显细化,εr也随之增加,tanδ先降低后增加,其弥散性指数均介于1.7~1.9。在x为0.25时,材料为两相共存结构,其εr峰值达到2353.22,tanδ仅为0.058,d33达到80pC/N,Ec为1.71×103V/mm,表现出优异的介电和压电性能。 相似文献
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65.
讨论了一种可用于红外探测的有机铁电聚偏二氟乙烯材料结构、性能与应用方面的若干问题,包括结构及其衍生物、制备与性能、弛豫铁电特性、在红外探测方面的应用以及铁电隧道结新型器件等。 相似文献
66.
我们报道了用高分辨布里渊散射,确定0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3单晶中的弹性、压电和介电常数.所有的实验数据都是在一块沿[001]方向的极化的单晶样品上获得的。我们实验中得到的这些常数的数值和以往超声共振技术获得的数值相似。我们还研究了压缩模和剪切模在(010)和(001)平面内的方向依赖性。TA1和TA2模式的强度对散射角度有很强列依赖性。在散射角度为45°~65°内, 一个新的峰出现在~18 GHz附近。它可能与晶体中的微观不均匀性或者局域微结构相关。 相似文献
67.
Smitha Shetty Anoop Damodaran Ke Wang Yakun Yuan Venkat Gopalan Lane Martin Susan Trolier‐McKinstry 《Advanced functional materials》2019,29(5)
The local compositional heterogeneity associated with the short‐range ordering of Mg and Nb in PbMg1/3Nb2/3O3 (PMN) is correlated with its characteristic relaxor ferroelectric behavior. Fully ordered PMN is not prepared as a bulk material. This work examines the relaxor behavior in PMN thin films grown at temperatures below 1073 K by artificially reducing the degree of disorder via synthesis of heterostructures with alternate layers of Pb(Mg2/3Nb1/3)O3 and PbNbO3, as suggested by the random‐site model. 100 nm thick, phase‐pure films are grown epitaxially on (111) SrTiO3 substrates using alternate target timed pulsed‐laser deposition of Pb(Mg2/3Nb1/3)O3 and PbNbO3 targets with 20% excess Pb. Selected area electron diffraction confirms the emergence of (1/2, 1/2, 1/2) superlattice spots with randomly distributed ordered domains as large as ≈150 nm. These heterostructures exhibit a dielectric constant of 800, loss tangents of ≈0.03 and 2× remanent polarization of ≈11 µC cm?2 at room temperature. Polarization–electric field hysteresis loops, Rayleigh data, and optical second‐harmonic generation measurements are consistent with the development of ferroelectric domains below 140 K. Temperature‐dependent permittivity measurements demonstrate reduced frequency dispersion compared to short range ordered PMN films. This work suggests a continuum between normal and relaxor ferroelectric behavior in the engineered PMN thin films. 相似文献
68.
Elastic–plastic deformation of Pb(Zn1/3Nb2/3)O3–(6–7)% PbTiO3 single crystals during nanoindentation
Meng Fei Wong 《哲学杂志》2013,93(13):1685-1700
The elastic–plastic deformation behavior of (001)- and (011)-oriented single crystal solid solutions of Pb(Zn1/3Nb2/3)O3–(6–7)% PbTiO3 (PZN–PT) have been studied using a nanoindentation technique. A procedure is presented here to isolate the elastic, elastic–plastic and plastic contributions to the deformation using the unloading data, and a parameter, referred to as relaxation, is defined to characterize the elastic–plastic deformation during nanoindentations. This relaxation parameter increases with the maximum indentation load due to the higher indentation stress induced, and it also causes less recovery of the material upon indentation unloading compared to predicted pure elastic recovery. For a (001) surface, the relaxation value remains virtually unchanged within the range of the maximum indentation load of 10–50 mN, possibly due to a complete localized depoling of the non-180° domain switching. It is also found that the unpoled surface is more prone to stress-induced depolarization compared to the poled surfaces. Furthermore, by applying the continuous stiffness measurement (CSM) technique, the effects of multiple loading/unloading are studied for both (001)- and (011)-oriented PZN–PTs using the maximum indentation loads of 20 and 50 mN. With more loading/unloading cycles at higher CSM frequencies, stress-induced depolarization becomes prevalent and the contribution of the domain reorientation towards elastic recovery is significantly reduced. As a consequence, the relaxation value is increased, indicating more elastic–plastic deformation. This CSM effect is especially pronounced for poled (011) surfaces. 相似文献
69.
J. Kroupa V. Bovtun D. Nuzhnyy M. Savinov P. Vanek S. Kamba 《Phase Transitions》2013,86(11-12):1059-1064
We investigated the grain size effect on the high temperature behaviour of PMN-35PT ceramics around the tetragonal–cubic phase transition using second harmonic generation (SHG) and dielectric spectroscopy. Our data revealed coexistence of the first-order ferroelectric phase transition and relaxor behaviour in the coarse grain (grain size ~4 µm) µ_PMN-35PT. The phase transition is hindered and relaxor features prevail in the fine grain (grain size ~150 nm) n_PMN-35PT ceramics. Effect of the grain-size reduction on the SHG and dielectric response could be attributed to stabilisation of intermediate domain configurations between the frozen polar nanoclusters and large ferroelectric domains and to the enhanced stability of polar nanoclusters in the fine grain ceramics. 相似文献
70.
C. E. Ciomaga M. T. Buscaglia M. Viviani V. Buscaglia L. Mitoseriu A. Stancu 《Phase Transitions》2013,86(6-7):389-397
BaZr0.1Ti0.9O3 ceramics with grain sizes of 0.75 and 2.60?µm have been prepared via solid-state reaction. Optimum parameters for calcination and sintering have been found in order to obtain pure perovskite phase, high density ceramics and homogeneous microstructures. The dielectric data show a diffuse phase transition with a mixed ferroelectric-relaxor character at a maximum at 87–92°C, with a small thermal hysteresis of 2–3°C. A tendency towards a more diffuse character of the ferro–para phase transition towards the full relaxor behaviour is observed as small in the ceramic grain size. Better dielectric properties in the coarse ceramics with higher permittivity up to 14,000 at the transition temperature by comparison with 5000 for the fine one, are observed as a consequence of higher tetragonal distortion and higher density. The differences in the dielectric spectra found for the two grain sizes were interpreted as a consequence of the higher degree of inhomogeneity in the fine ceramics and to different grain boundary properties induced by the different sintering temperatures. 相似文献