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采用平均场近似下的横场伊辛模型理论,引入描述铁电畸变的分布函数,同时考虑量子起伏效应,研究了温度梯度铁电材料的极化偏移特性,重点针对小温差情况下温度梯度铁电材料极化偏移消失的实验现象进行了理论验证。研究表明,温度梯度的存在导致了材料内部的极化强度的梯度分布,量子起伏效应对温度梯度铁电材料的性质有十分重要的影响,本工作关于温度梯度铁电材料极化偏移的研究结果与实验研究取得了定性一致的结论。当同时在考虑铁电畸变和量子起伏效应时,小温差情况下温度梯度铁电材料极化偏移消失的实验现象得以验证。 相似文献
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Ferroelectric and Piezoelectric Effects on the Optical Process in Advanced Materials and Devices
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Yang Zhang Wenjing Jie Ping Chen Weiwei Liu Jianhua Hao 《Advanced materials (Deerfield Beach, Fla.)》2018,30(34)
Piezoelectric and ferroelectric materials have shown great potential for control of the optical process in emerging materials. There are three ways for them to impact on the optical process in various materials. They can act as external perturbations, such as ferroelectric gating and piezoelectric strain, to tune the optical properties of the materials and devices. Second, ferroelectricity and piezoelectricity as innate attributes may exist in some optoelectronic materials, which can couple with other functional features (e.g., semiconductor transport, photoexcitation, and photovoltaics) in the materials giving rise to unprecedented device characteristics. The last way is artificially introducing optical functionalities into ferroelectric and piezoelectric materials and devices, which provides an opportunity for investigating the intriguing interplay between the parameters (e.g., electric field, temperature, and strain) and the introduced optical properties. Here, the tuning strategies, fundamental mechanisms, and recent progress in ferroelectric and piezoelectric effects modulating the optical properties of a wide spectrum of materials, including lanthanide‐doped phosphors, quantum dots, 2D materials, wurtzite‐type semiconductors, and hybrid perovskites, are presented. Finally, the future outlook and challenges of this exciting field are suggested. 相似文献
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From the appearance of the laser, 50 years ago, the use of ferroelectric crystals in optical devices has constituted a field of much interest and activity. Ferroelectric materials have been employed successfully in nonlinear passive optical systems such as frequency mixers, optical parametric oscillators, and modulators of light.In the last years it has been demonstrated that several ferroelectric materials can also operate as active optical systems generating laser action when the suitable optically active impurities are incorporated into the crystals.Here, it will be shown how some important features offered by ferroelectric materials (nonlinearity, presence of ferroelectric domains, phase transition, thermal hysteresis, …) can be exploited in order to provide solid state lasers with a reliable multifunctional optical character. 相似文献
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Lee W Han H Lotnyk A Schubert MA Senz S Alexe M Hesse D Baik S Gösele U 《Nature nanotechnology》2008,3(7):402-407
Ferroelectric materials have emerged in recent years as an alternative to magnetic and dielectric materials for nonvolatile data-storage applications. Lithography is widely used to reduce the size of data-storage elements in ultrahigh-density memory devices. However, ferroelectric materials tend to be oxides with complex structures that are easily damaged by existing lithographic techniques, so an alternative approach is needed to fabricate ultrahigh-density ferroelectric memories. Here we report a high-temperature deposition process that can fabricate arrays of individually addressable metal/ferroelectric/metal nanocapacitors with a density of 176 Gb inch(-2). The use of an ultrathin anodic alumina membrane as a lift-off mask makes it possible to deposit the memory elements at temperatures as high as 650 degrees C, which results in excellent ferroelectric properties. 相似文献
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Kalinin SV Rar A Jesse S 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(12):2226-2252
Coupling between electrical and mechanical phenomena is a near-universal characteristic of inorganic and biological systems alike, with examples ranging from piezoelectricity in ferroelectric perovskites to complex, electromechanical couplings in electromotor proteins in cellular membranes. Understanding electromechanical functionality in materials such as ferroelectric nanocrystals and thin films, relaxor ferroelectrics, and biosystems requires probing these properties on the nanometer level of individual grain, domain, or protein fibril. In the last decade, piezoresponse force microscopy (PFM) was established as a powerful tool for nanoscale imaging, spectroscopy, and manipulation of ferroelectric materials. Here, we present principles and recent advances in PFM, including vector and frequency-dependent imaging of piezoelectric materials, briefly review applications for ferroelectric materials, discuss prospects for electromechanical imaging of local crystallographic and molecular orientations and disorder, and summarize future challenges and opportunities for PFM emerging in the second decade since its invention 相似文献
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Science and technology of ferroelectric films and heterostructures for non-volatile ferroelectric memories 总被引:7,自引:0,他引:7
We present in this article a review of the status of thin film ferroelectric materials for nonvolatile memories. Key materials issues relevant to the integration of these materials on Si wafers are discussed. The effect of film microstructure and electrode defect chemistry on the ferroelectric properties relevant to a high density nonvolatile memory technology are discussed. The second part of this review focuses on approaches to integrate these capacitor structures on a filled poly-Si plug which is a critical requirement for a high density memory technology. Finally, the use of novel surface probes to study and understand broadband polarization dynamics in ferroelectric thin films is also presented. 相似文献
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Science and technology in the electronics area have always been driven by the development of materials with unique properties and their integration into novel device concepts with the ultimate goal to enable new functionalities in innovative circuit architectures. In particular, a shift in paradigm requires a synergistic approach that combines materials, devices and circuit aspects simultaneously. Here we report the experimental implementation of a novel nonvolatile memory cell that combines silicon nanowires with an organic ferroelectric polymer-PVDF-TrFE-into a new ferroelectric transistor architecture. Our new cell, the ferroelectric transistor random access memory (FeTRAM) exhibits similarities with state-of-the-art ferroelectric random access memories (FeRAMs) in that it utilizes a ferroelectric material to store information in a nonvolatile (NV) fashion but with the added advantage of allowing for nondestructive readout. This nondestructive readout is a result of information being stored in our cell using a ferroelectric transistor instead of a capacitor-the scheme commonly employed in conventional FeRAMs. 相似文献
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A discussion is presented of new directions in ferroelectric random access memories (FRAMs) and ferroelectric capacitors for dynamic random access memories (DRAMs), emphasizing [3D] structures and new materials, as well as ferroelectric gates and new mechanisms of domain wall motion in nano-scale geometries. 相似文献
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以铁电性的钛酸锶钡(BST)和铁磁性钇铁氧体(YIG)为原料,采用固相反应法,合成了一系列铁电/铁磁复合材料,并对铁电/铁磁复合材料(YIG/BST)的介电性能和磁性能进行了详细地研究. 结果表明:在一定温度下烧结所得的铁电/铁磁复合材料,由铁电相和铁磁相两相组成;xBST-(1-x)YIG(x=0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1.0)复合材料具有良好的介电性能和磁性能, 其介电常数实部ε′与虚部ε″均随BST含量的增加而升高,且介电常数的谐振峰随着YIG含量的增加而向频率高的方向移动.磁导率实部μ′与虚部μ″均随BST含量的增加而降低. 在YIG铁氧体中加入适量的陶瓷BST构成复合材料,可以有效地改善截止频率,提高高频电磁特性. 相似文献
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Mahshid Ahmadi Liam Collins Alexander Puretzky Jia Zhang Jong Kahk Keum Wei Lu Ilia Ivanov Sergei V. Kalinin Bin Hu 《Advanced materials (Deerfield Beach, Fla.)》2018,30(11)
Organometallic halide perovskites (OMHPs) have attracted broad attention as prospective materials for optoelectronic applications. Among the many anomalous properties of these materials, of special interest are the ferroelectric properties including both classical and relaxor‐like components, as a potential origin of slow dynamics, field enhancement, and anomalous mobilities. Here, ferroelectric properties of the three representative OMHPs are explored, including FAPbxSn1–xI3 (x = 0, x = 0.85) and FA0.85MA0.15PbI3 using band excitation piezoresponse force microscopy and contact mode Kelvin probe force microscopy, providing insight into long‐ and short‐range dipole and charge dynamics in these materials and probing ferroelectric density of states. Furthermore, second‐harmonic generation in thin films of OMHPs is observed, providing a direct information on the noncentrosymmetric polarization in such materials. Overall, the data provide strong evidence for the presence of ferroelectric domains in these systems; however, the domain dynamics is suppressed by fast ion dynamics. These materials hence present the limit of ferroelectric materials with spontaneous polarization dynamically screened by ionic and electronic carriers. 相似文献
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不挥发铁电存储器的最新发展 总被引:6,自引:2,他引:4
铁电材料具有自发极化并可由外电场反转,因此可以构成一种不挥发存储器.铁电薄膜与半导体集成,产生铁电随机存储器,并将成为存储器技术的主体. 相似文献
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David Vanderbilt 《Current Opinion in Solid State & Materials Science》1997,2(6):701-705
The application of first-principles computational methods to the study of ferroelectric perovskites has greatly expanded our theoretical understanding of this important class of materials. These methods have most recently been applied to an increasingly wide range of ferroelectric materials, with special attention to their lattice dynamics, phase transitions, dielectric and piezoelectric properties, and to the study of defects and surfaces. 相似文献
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Tunnel junctions with multiferroic barriers 总被引:2,自引:0,他引:2
Gajek M Bibes M Fusil S Bouzehouane K Fontcuberta J Barthélémy A Fert A 《Nature materials》2007,6(4):296-302
Multiferroics are singular materials that can exhibit simultaneously electric and magnetic orders. Some are ferroelectric and ferromagnetic and provide the opportunity to encode information in electric polarization and magnetization to obtain four logic states. However, such materials are rare and schemes allowing a simple electrical readout of these states have not been demonstrated in the same device. Here, we show that films of La(0.1)Bi(0.9)MnO(3) (LBMO) are ferromagnetic and ferroelectric, and retain both ferroic properties down to a thickness of 2 nm. We have integrated such ultrathin multiferroic films as barriers in spin-filter-type tunnel junctions that exploit the magnetic and ferroelectric degrees of freedom of LBMO. Whereas ferromagnetism permits read operations reminiscent of magnetic random access memories (MRAM), the electrical switching evokes a ferroelectric RAM write operation. Significantly, our device does not require the destructive ferroelectric readout, and therefore represents an advance over the original four-state memory concept based on multiferroics. 相似文献
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V. V. Titov L. A. Reznichenko S. V. Titov V. D. Komarov V. A. Akhnazarova 《Technical Physics Letters》2004,30(4):278-280
The process of grain structure formation and development in ferroelectric ceramics based on sodium noiobate are considered.
Micrographs of the grain boundary regions are described in terms of multifractal parameters. Correlations between the multifractal
and structural parameters of ferroelectric niobate ceramics are found. The process of secondary interrupted recrystallization
has been studied. The results have been used for optimization of the technology of novel ferroelectric materials. 相似文献
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Ferroelectric ceramics are important electronic materials that have a wide range of industrial and commercial applications, such as high-dielectric constant capacitors, piezoelectric sonar or ultrasonic transducers, pyroelectric security sensors, medical diagnostic transducers, electro-optical light valves, and ultrasonic motors, to name a few. The performances of ferroelectrics are closely related to the ways they are processed. The conventional solid state reaction method requires high calcination and sintering temperatures, resulting in the loss of lead, bismuth or lithium components due to their high volatilities, thus worsening the microstructural and subsequently the electrical properties of the ferroelectric materials. Various wet chemistry based routes have been developed to synthesize ultra-fine and even nano-sized ferroelectric powders. However, most of the chemistry based routes still involve calcinations, although at relatively lower temperatures. High energy mechanochemical milling process has been shown that some ferroelectric materials can be synthesized directly from their oxide precursors in the form of nano-sized powders, without the need for the calcination at intermediate temperatures, thus making the process very simple and cost-effective. A large number of ferroelectric materials, including lead-containing ferroelectrics, antiferroelectrics and relaxors, and bismuth-containing Aurivillius families, have been synthesized by the high-energy milling process. Some ferroelectrics, such as barium titanate (BaTiO3 or BT), lead iron tungstate [Pb(Fe2/3W1/3)O3 or PFW], and several bismuth-containing materials, that cannot be directly produced from their oxide mixtures, have been formed at relatively low temperature after their precursors are activated by an high-energy milling. Ferroelectric ceramics derived from the activated precursors demonstrated better microstructure and electrical properties than those without mechanochemical treatment. This review presents an overview of the recent progress in the synthesis of ferroelectric ceramic powders using various high-energy milling techniques. The progress includes several aspects: (i) direct synthesis of nano-sized powders with better sinterability, (ii) promoted reactive sintering due to the modification of the precursors, (iii) amorphization of the precursors, and (iv) refinement of the precursors with high homogeneity. The underlying mechanisms of mechanochemical synthesis of ferroelectric materials are discussed. Further research emphasizes on issues related to the synthesis of ferroelectric ceramic powders are suggested. 相似文献