共查询到19条相似文献,搜索用时 62 毫秒
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弛豫铁电单晶及织构陶瓷的研究进展 总被引:2,自引:0,他引:2
综述了近年来弛豫铁电单晶和织构陶瓷的制备及其介电、压电性能的研究进展。弛豫铁电单晶的制备方法主要有高温溶液法、布里奇曼法和固态再结晶法,尺寸可达40mm以上,(001)切片压电常数d33最大可达3000pC/N,k3达到0.93,但是成分不均匀仍是影响晶体压电性能的一个主要因素。织构陶瓷的制备方法主要为固态再结晶法(TGG法和RTGG法),其耗时短、成本低,压电性能可达到单晶的60%~80%,介电常数甚至可以超过部分单晶,是一个新的发展方向。 相似文献
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锰掺杂对PMN-PT陶瓷介电和压电特性的影响 总被引:1,自引:1,他引:1
采用氧化物固相反应法制备了Mn掺杂0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3陶瓷,研究了锰掺杂量对陶瓷相结构、介电和压电性能的影响。实验发现,随着锰掺杂量的增加,陶瓷焦绿石相含量的逐渐较少,材料变“硬”。即当锰掺杂量少于1.5mol%时,介电系数ε、压电常数d33和机械品质因数Qm逐渐增加,介电损耗tanδ减少。随着锰掺杂量的进一步增加,弛豫程度变得更加明显。当压电陶瓷组分中锰掺杂量为1.5mol%时,其介电和压电性能各为:ε=2300,kp=0.54,Qm=900,tanδ=0.004,d33=400pC/N,适于制作大功率压电陶瓷变压器。 相似文献
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PMNT单晶电畴结构随组分与结构的变化 总被引:1,自引:0,他引:1
利用多种方法观察了弛豫型铁电单晶PMNT中电畴结构随组分与结构的演变过程与特征.观察发现,在PMN-PT的三方相区内,随PT含量的增加,电畴结构表现出微畴一(亚微畴)-不规则宏畴一规则宏畴转变历程;在三方-四方相变中,非180°电畴发生71°(或109°)宏畴-90°宏畴的转化,同时电畴图像变得更为规则.根据不同组分PMNT电畴的显示特征,提出晶体的最大双折射率可以作为度量其弛豫性强弱的光学参数.观察到了电畴的分布不均匀与多级结构现象,前者与组分或结构的起伏有关,后者与多期式马氏体转变有关.本文还分析了偏光显微镜、DIC、SEM、SEAM等观察方法中电畴的成像特征. 相似文献
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Piezoresponse force microscopy studies of nanoscale domain structures in ferroelectric thin film 总被引:2,自引:0,他引:2
H.R. Zeng H.F. Yu X.G. Tang R.Q. Chu G.R. Li Q.R. Yin 《Materials Science and Engineering: B》2005,120(1-3):104-108
Piezoresponse force microscopy was used to perform studies of nanoscale domain imaging, limit of ferroelectric nano-sized grains and electric field-induced displacement behavior of domain structures in ferroelectric PZT thin film. Nanoscale 180° and 90° domain configurations as small as 30 nm in size were clearly visualized in the individual grains. It was demonstrated that domain configuration was strongly dependent on the size of the grains. The limit of ferroelectric nano-sized grains was found to be smaller than 25 nm. Nanoscale displacement versus field hysteresis loops were obtained in ferroelectric domains of PZT thin film, and discussed in terms of phenomenological theory. 相似文献
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Piezoresponse force microscopy and recent advances in nanoscale studies of ferroelectrics 总被引:1,自引:0,他引:1
In this paper, we review recent advances in piezoresponse force microscopy (PFM) with respect to nanoscale ferroelectric research,
summarize the basic principles of PFM, illustrate what information can be obtained from PFM experiments and delineate the
limitations of PFM signal interpretation relevant to quantitative imaging of a broad range of piezoelectrically active materials.
Particular attention is given to orientational PFM imaging and data interpretation as well as to electromechanics and kinetics
of nanoscale ferroelectric switching in PFM. 相似文献
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The rotational striations and power striations are studied in LiNbO3 crystals and one-to-one correspondence between the striations and temperature fluctuations is demonstrated. The ferroelectric domain structures related to the rotational striations and the power striations have been observed. The distribution of solute concentration in rotational striations is measured by means of energy dispersive X-ray analysis in the scanning electron microscope, and it has been concluded that the ferroelectric domain structures depend on the solute concentration gradient. 相似文献
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Wong KS Wang B Dai JY Luo H 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(5):952-956
Ferroelectric domain structures in (001)-cut Pb(Mg(1/3)Nb(2/3))O(3)-38%PbTiO(3) and (011)-cut Pb(Mg(1/3) Nb(2/3))O(3)-60%PbTiO(3) single crystals are studied by means of piezoresponse force microscopy (PFM). The out-of-plane- polarization (OPP) and in-plane-polarization (IPP) domain piezoresponse imaging reveals the domain and domain boundary configurations in these two different PbTiO(3)-content crystals. Finite-element analysis is carried out to illustrate the OPP and IPP-PFM imagings mechanism and interpret the domains superposition phenomenon during PFM imaging. 相似文献
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Dague E Alsteens D Latgé JP Verbelen C Raze D Baulard AR Dufrêne YF 《Nano letters》2007,7(10):3026-3030
Traditionally, cell surface properties have been difficult to study at the subcellular level, especially on hydrated, live cells. Here, we demonstrate the ability of chemical force microscopy to map the hydrophobicity of single live cells with nanoscale resolution. After validating the technique on reference surfaces with known chemistry, we probe the local hydrophobic character of two medically important microorganisms, Aspergillus fumigatus and Mycobacterium bovis, in relation with function. Applicable to a wide variety of cells, the chemically sensitive imaging method presented here provides new opportunities for studying the nanoscale surface properties of live cells and for understanding their roles in mediating cellular events. 相似文献
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Mechanical Stress fields of nearly radial symmetry are produced by focused laser irradiation on (111) surfaces of copper single crystals. The dislocation structures in the vicinity of the heat-affected zone can be revealed with the aid of an etch pit technique. The observed etch pit pattern is in very good agreement with calculations based on dislocation theory. 相似文献
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K Cramer M. Fogliato Santos Lima S. N Magonov E. H Hellmann M Jacobs G. P Hellmann 《Journal of Materials Science》1998,33(9):2305-2312
Polyvinylidene fluoride (PVDF), in homogeneous blends with an amorphous polymer under specific conditions, forms crystals with a tree-like architecture. Tree-like crystals have a loose fractal structure of crystalline branches which are impregnated with the amorphous polymer. In a previous study, this spectacular morphology was investigated in blends of PVDF and a random copolymer of styrene and methylmethacrylate (SMMA, 13% wt/wt styrene) by light microscopy. The crystal growth was interpreted in terms of a rate competition of crystallization and interdiffusion. The submicroscopic structure of tree-like PVDF spherulites has now been characterized by atomic force microscopy. Surface profiles were prepared by etching PVDF/SMMA blend films with toluene. The tree-like spherulites proved to be less disordered than expected. Their core consists of a compact array of lamellae, the planes of which are periodically twisted, producing a ring pattern. Near the crystallizing front, branches grow, separated from each other, into the amorphous phase. They are internally as compact as the core, but are covered by a loose fur of disordered lamellae. The tree-like appearance of these crystals comes from frequent splitting of the branches into twigs. Crystallographic bifurcation as in dendritic crystals was not observed. At interfaces between two tree-like crystals, the lamellae form patterns of backfolding. © 1998 Chapman & Hall 相似文献
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Fracture studies of tungsten single crystals 总被引:1,自引:0,他引:1
J. Riedle P. Gumbsch H.F. Fischmeister V.G. Glebovsky V.N. Semenov 《Materials Letters》1994,20(5-6):311-317
For fracture studies on oriented W monocrystalline specimens it is necessary to produce very sharp, stopped precracks, which presents difficulties in the case of W. The procedure and technique to produce precracks is described. The fracture experiments gave strong indications for a preference of the {100} planes as cleavage planes. The {110} planes successfully resist crack propagation, although they are the planes with the lowest surface energy. Crack propagation on both the {110} crack system and {100} crack system is strongly influenced by the crack front orientation. The appearance of the {121} plane as a cleavage plane in our experiments makes further studies with oriented W monocrystalline specimens desirable. 相似文献