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John Mangeri, Yomery Espinal, Andrea Jokisaari, S Pamir Alpay, Serge Nakhmanson, Olle Heinonen
Composite materials comprised of ferroelectric nanoparticles in a dielectric matrix are being actively investigated for a variety of functional properties attractive for a wide range of novel electronic and energy harvesting devices. However, the dependence of these functionalities on shapes, sizes, orientation and mutual arrangement of ferroelectric particles is currently not fully understood. In this study, we utilize a time-dependent Ginzburg-Landau approach combined with coupled-physics finite-element-method based simulations to elucidate the behavior of polarization in isolated spherical PbTiO3 or BaTiO3 nanoparticles embedded in a dielectric medium, including air...
January 11, 2017: Nanoscale
Koshi Takenaka, Yoshihiko Okamoto, Tsubasa Shinoda, Naoyuki Katayama, Yuki Sakai
Large negative thermal expansion (NTE) has been discovered during the last decade in materials of various kinds, particularly materials associated with a magnetic, ferroelectric or charge-transfer phase transition. Such NTE materials have attracted considerable attention for use as thermal-expansion compensators. Here, we report the discovery of giant NTE for reduced layered ruthenate. The total volume change related to NTE reaches 6.7% in dilatometry, a value twice as large as the largest volume change reported to date...
January 10, 2017: Nature Communications
Halid Mulaosmanovic, Johannes Ocker, Stefan Mueller, Uwe Schroeder, Johannes Müller, Patrick Polakowski, Stefan Flachowsky, Ralf van Bentum, Thomas Mikolajick, Stefan Slesazeck
Recent discovery of ferroelectricity in thin hafnium oxide films has led to a resurgence of interest in ferroelectric memory devices. Although both experimental and theoretical studies on this new ferroelectric system have been undertaken, much remains to be unveiled regarding its domain landscape and switching kinetics. Here we demonstrate that the switching of single domains can be directly observed in ultra-scaled ferroelectric field effect transistors. Using models of ferroelectric domain nucleation we explain the time, field and temperature dependence of polarization reversal...
January 10, 2017: ACS Applied Materials & Interfaces
Kenji Takashima, Yukio Furukawa
Voltage-induced infrared spectra of annealed spin-cast thin films of ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) (molar ratio, 3:1) were measured in a stepwise cyclic external electric field. Most of the observed infrared bands originated from the β ferroelectric crystalline phase. The voltage-induced spectral changes were decomposed into zeroth- (original), first-, and second-derivative spectra, and were attributed to the rotational motions of the polymer chains and the vibrational Stark effect...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Zhongbin Pan, Lingmin Yao, JiWei Zhai, Dezhou Fu, Bo Shen, Haitao Wang
Flexible electrostatic capacitors are potentially applicable in modern electrical and electric power systems. In this study, flexible nanocomposites containing newly-structured one-dimensional (1D) BaTiO3@Al2O3 nanofibers (BT@AO NFs) and the ferroelectric polymer poly(vinylidene fluoride) (PVDF) matrix were prepared and systematically studied. The 1D BT@AO NFs, where BaTiO3 nanoparticles (BT NPs) were embedded and homogenously dispersed into the AO nanofibers, were successfully synthesized via an improved electrospinning technique...
January 9, 2017: ACS Applied Materials & Interfaces
Ian Gilbert, Andres C Chavez, Daniel T Pierce, John Unguris, Wei-Yang Sun, Cheng-Yen Liang, Gregory P Carman
Strain-mediated thin film multiferroics comprising piezoelectric/ferromagnetic heterostructures enable the electrical manipulation of magnetization with much greater efficiency than other methods; however, the investigation of nanostructures fabricated from these materials is limited. Here we characterize ferromagnetic Ni nanostructures grown on a ferroelectric PMN-PT substrate using scanning electron microscopy with polarization analysis (SEMPA) and micromagnetic simulations. The magnetization of the Ni nanostructures can be controlled with a combination of sample geometry and applied electric field, which strains the ferroelectric substrate and changes the magnetization via magnetoelastic coupling...
October 2016: Applied Physics Letters
Xin Chen, Krzysztof Switkowski, Xiaopeng Hu, Wieslaw Krolikowski, Yan Sheng
We introduce a custom-cut periodically poled ferroelectric crystal for the phase matching of multistep cascading frequency conversion processes. Our approach involves combination of collinear second harmonic generation and transverse sum frequency mixing via the total internal reflection of the fundamental and collinear second harmonic beams. As a proof of concept we demonstrate multiple frequency generation with an enhanced fourth harmonic signal in a one-dimensional periodically poled LiNbO<sub>3</sub> crystal...
December 26, 2016: Optics Express
Ping-Ping Shi, Yuan-Yuan Tang, Peng-Fei Li, Heng-Yun Ye, Ren-Gen Xiong
To date, the field of ferroelectric random access memories (FeRAMs) is mainly dominated by inorganic ferroelectric thin films like Pb(Zr,Ti)O3, which suffer from the issues of environmental harmfulness, high processing temperatures and high fabrication costs. In these respects, molecular ferroelectric thin films are particularly advantageous and thus become promis-ing alternatives to the conventional inorganic ones. For the prospect of FeRAMs applications, they should fulfill the require-ments of effective polarization switching and low-voltage, high-speed operation...
January 6, 2017: Journal of the American Chemical Society
Chunrui Ma, Rongtao Lu, Guangliang Hu, Jinsheng Han, Ming Liu, Jun Li, Judy Z Wu
Graphene were inserted the interface between electric dipole layers from the DEME-TFSI ionic liquid (top gate) and ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT, back-gate) to probe the interface dipole-dipole interaction in response to DC and pulsed gate voltages. A highly complicated behavior of the interface dipole-dipole interaction has been revealed as a combination of electrostatic and electrochemical effects. The interfacial polar molecules in the DEME-TFSI electrical double layer are pinned with assistance of the PLZT back-gate in response to a DC top-gate pump, leading to strong nonlinear electrochemical behavior...
January 6, 2017: ACS Applied Materials & Interfaces
Vladimir Shirokov, Anna Razumnaya, Yu Yuzyuk
We studied the influence of the induced strain and applied electric field on the ground state of ferroelectric Ba0.7Sr0.3TiO3 thin films, deposited on the cubic (001) substrate. The dependence of the pyroelectric coefficient on the applied field is calculated for the different values of the induced strain. We found that tuning of the misfit strain in the film under the dielectric bolometer mode by the proper selection of substrate makes it possible to create the structures with very large values of the pyroelectric coefficient...
January 5, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Sergey G Arkhipov, Evgeniy A Losev, Elena V Boldyreva
Molecular salts and cocrystals of amino acids have potential applications as molecular materials with nonlinear optical, ferroelectric, piezoelectric, and other various target physical properties. The wide choice of amino acids and coformers makes it possible to design various crystal structures. The amino acid-maleic acid system provides a perfect example of a rich variety of crystal structures with different stoichiometries, symmetries and packing motifs built from the molecular building blocks, which are either exactly the same, or differ merely by protonation or as optical isomers...
January 1, 2017: Acta Crystallographica. Section C, Structural Chemistry
Jian-Qing Dai, Jie-Wang Xu, Jian-Hui Zhu
The relative stability of multiferroic BiFeO3 (0001) surfaces, which is the (111) facet in the pseudocubic notation, with different stoichiometry is systematically studied by using ab-initio thermodynamic approach in order to obtain insights into the stable surface terminations. We predict that, under most chemical potential conditions, the thermodynamically favored terminations for the negative and positive surfaces are -Bi-O2 and -Fe-O3-Bi, respectively. The predicted difference in oxygen content between the negative and positive surfaces is consistent with experimental observations at the BiFeO3/metal interfaces [Nat...
December 29, 2016: ACS Applied Materials & Interfaces
Peisen Li, Yonggang Zhao, Sen Zhang, Aitian Chen, Dalai Li, Jing Ma, Yan Liu, Daniel T Pierce, John Unguris, Hong-Guang Piao, Huiyun Zhang, Meihong Zhu, Xiaozhong Zhang, Xiufeng Han, Mengchun Pan, Ce-Wen Nan
Intrinsic spatial inhomogeneity or phase separation in cuprates, manganites, etc., related to electronic and/or magnetic properties, has attracted much attention due to its significance in fundamental physics and applications. Here we use scanning Kerr microscopy and scanning electron microscopy with polarization analysis with in situ electric fields to reveal the existence of intrinsic spatial inhomogeneity of the magnetic response to an electric field on a mesoscale with the coexistence of looplike (nonvolatile) and butterfly-like (volatile) behaviors in Co40Fe40B20/Pb(Mg1/3Nb2/3)0...
January 9, 2017: ACS Applied Materials & Interfaces
Mehrshad Mehboudi, Benjamin M Fregoso, Yurong Yang, Wenjuan Zhu, Arend van der Zande, Jaime Ferrer, L Bellaiche, Pradeep Kumar, Salvador Barraza-Lopez
GeSe and SnSe monochalcogenide monolayers and bilayers undergo a two-dimensional phase transition from a rectangular unit cell to a square unit cell at a critical temperature T_{c} well below the melting point. Its consequences on material properties are studied within the framework of Car-Parrinello molecular dynamics and density-functional theory. No in-gap states develop as the structural transition takes place, so that these phase-change materials remain semiconducting below and above T_{c}. As the in-plane lattice transforms from a rectangle into a square at T_{c}, the electronic, spin, optical, and piezoelectric properties dramatically depart from earlier predictions...
December 9, 2016: Physical Review Letters
Shujuan Liu, Lixue Zhang, Jiping Wang, Xiujing Shi, Yingying Zhao, Dawei Zhang
In this work, we report a rapid stability phenomenon of ferroelectric polarization in the Ca, Ce hybrid doped BaTiO3 ceramics (BCaxT+BTCe8) (x = 10, 20, 24, 30 mol%) prepared by separate doping Ca(2+) and Ce(4+) ions. Double hysteresis loops are identified in the aged BCaxT+BTCe8 samples; meanwhile, the polarization of these loops present a rapid decrease within very short aging time (about 1 h), and then the polarization remains almost unchanged over the followed ~1000 h. This phenomenon is not reported in previous researches...
December 22, 2016: Scientific Reports
Xi-Guang Wang, Alexander Sukhov, Levan L Chotorlishvili, Chenglong Jia, Guang-Hua Guo, Jamal Berakdar
We suggest and demonstrate via large scale numerical simulations an electrically operated spin- wave inducer based on composite multiferroic junctions. Specifcally, we consider an interfacially coupled ferromagnetic/ferroelectric structure that emits controllably spin waves in the ferromagnets if the ferroelectric polarization is poled by an external electric feld. The roles of geometry and material properties are discussed.
December 22, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Min Zhou, Xiaomei Lu, Dianyuan Yang, Ju He, Fengzhen Huang, Fang Mei, Xianming Ren, Xingyu Xu, Yang Li, Jinsong Zhu
The relationship among dielectric anomaly, ferroelectric response, defects, and microstructures was established for (K0.48(1+x)Na0.52)0.95Li0.05Nb0.95Sb0.05O3 (x = 0.04, 0.00, -0.02, -0.04 and -0.08) ceramics. For x = -0.02 and -0.04, larger coercive fields and lower remnant polarizations were obtained; besides, an additional dielectric relaxation behavior was observed with the activation energy Ea being about 2.19 eV and 1.92 eV, respectively. Furthermore, the grain and grain boundary contributions to the capacitance were separated using impedance spectroscopy, which, combined with back-scattering characterization, firmly indicates the core-shell structure of K-deficient samples (x = -0...
December 21, 2016: Physical Chemistry Chemical Physics: PCCP
Hajime Hojo, Ryo Kawabe, Keisuke Shimizu, Hajime Yamamoto, Ko Mibu, Kartik Samanta, Tanusri Saha-Dasgupta, Masaki Azuma
The coexistence and coupling of ferromagnetic and ferroelectric orders in a single material is crucial for realizing next-generation multifunctional applications. Here, the coexistence of such orders is confirmed at room temperature in epitaxial thin films of BiFe1-x Cox O3 (x ≤ 0.15), which manifests a spin structure change from a low-temperature cycloidal one to a high-temperature collinear one with canted ferromagnetism.
December 21, 2016: Advanced Materials
Qiwei Zhang, Yao Zhang, Haiqin Sun, Wei Geng, Xusheng Wang, Xihong Hao, Shengli An
High luminescent switching contrast of photochromic materials is extremely important in improving the sensitivity and resolution of optical switches and high-density optical data storage devices. To date, conventional methods, such as tuning absorption and emission bands based on electron or resonance energy transfer mechanisms in well-known organic photochromic molecules or compounds, have routinely been adopted to tune luminescent switching behavior. However, these strategies and mechanisms are not effectively applied to luminescence switching in inorganic materials because their crystal structures differ strongly from those of organic materials...
December 21, 2016: ACS Applied Materials & Interfaces
Arkadiusz Rudzki, Sławomir Zalewski, Beata Suchodolska, Jan Czerwiec, Mirosława D Ossowska-Chruściel, Janusz Chruściel
The results of studies conducted by means of complementary methods, differential scanning calorimetry, transmitted light intensity measurements, polarized optical microscopy, the electro-optical method, as well as dielectric relaxation spectroscopy of two new liquid crystal mixtures are presented. The first mixture is an equimolecular binary mixture consisting of two ferroelectric chiral liquid crystals from the homologous series, abbreviated as (S)-MHOBSn. The second mixture is a multicomponent mixture and consists of four mesogens from the homologous series of nOS5 as the base of the mixture, abbreviated as 610712 and chiral MHOBS8...
December 20, 2016: Journal of Physical Chemistry. B
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