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Weixuan Zhang, Kaiyang Cheng, Chao Wu, Yi Wang, Hongqiang Li, Xiangdong Zhang
Metamaterials, artificially structured electromagnetic (EM) materials, have enabled the realization of many unconventional EM properties not found in nature, such as negative refractive index, magnetic response, invisibility cloaking, and so on. Based on these man-made materials with novel EM properties, various devices are designed and realized. However, quantum analog devices based on metamaterials have not been achieved so far. Here, metamaterials are designed and printed to perform quantum search algorithm...
November 17, 2017: Advanced Materials
Jiyong Liang, Yizhuo Gu, Zhenchong Zhang, Shaokai Wang, Min Li, Zuoguang Zhang
The compacting structure of chlorine-doped continuous CNT sheet/polyvinylidene fluoride (Cl-CNT sheet/PVDF) was successfully optimized by means of hot-press treatment to improve mechanical and dielectric properties with high densification degree. Then, the densified Cl-CNT sheet/PVDF dielectric layer was inserted between two PVDF insulating layers to fabricate sandwich composite. It is found that the dielectric and mechanical properties are effectively enhanced, with the dielectric permittivity of 40.4 (@102 Hz), dielectric loss of 0...
November 17, 2017: Nanotechnology
Jin-Sung Park, Kyoung-Ho Kim, Min-Soo Hwang, Xing Zhang, Jung Min Lee, Jungkil Kim, Kyung-Deok Song, You-Shin No, Kwang-Yong Jeong, James F Cahoon, Sun-Kyung Kim, Hong-Gyu Park
We report the enhancement of light absorption in Si nanowire photovoltaic devices with one-dimensional dielectric or metallic gratings that are fabricated by a damage-free, precisely aligning, polymer-assisted transfer method. Incorporation of a Si3N4 grating with a Si nanowire effectively enhances the photocurrents for transverse-electric polarized light. The wavelength at which a maximum photocurrent is generated is readily tuned by adjusting the grating pitch. Moreover, the electrical properties of the nanowire devices are preserved before and after transferring the Si3N4 gratings onto Si nanowires, ensuring that the quality of pristine nanowires is not degraded during the transfer...
November 17, 2017: Nano Letters
Shizhao Liu, Joel Plawsky
A composite film made of a stable, gold nanoparticle (NP) array with well-controlled separation and size atop a TiO2 nanorod film was fabricated via the oblique angle deposition technique (OAD). The fabrication of the nanoparticle array is based on controlled, Rayleigh-instability-induced, solid-state dewetting of as-deposited gold aggregates on the TiO2 nanorods. It was found that the initial spacing between as-deposited gold aggregates along the vapor flux direction should be greater than the TiO2 inter-rod spacing created by 80° OAD in order to control the dewetting and produce NP arrays...
November 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Seung Min Lee, Jung Hwan Yum, Seonno Yoon, Eric S Larsen, Woo Chul Lee, Seong Keun Kim, Shahab Shervin, Weijie Wang, Jae-Hyun Ryou, Christopher W Bielawski, Jungwoo Oh
We have developed a beryllium oxide (BeO) thin film process by atomic layer deposition (ALD) and grown a single-crystal BeO on a gallium nitride (GaN) substrate for the first time. BeO has a higher thermal conductivity than all other metals except Cu, Ag, and Au, and it has a higher bandgap energy and dielectric constant than SiO2 and Al2O3. As an electrical insulator, diamond is the only material on Earth whose thermal conductivity exceeds that of BeO. Despite these advantages, there is no chemical vapor deposition technique for BeO thin film deposition, and thus, it is not used in nanoscale semiconductor device processing...
November 17, 2017: ACS Applied Materials & Interfaces
Wei-Li Song, Zhili Zhou, Lichen Wang, Xiao-Dong Cheng, Mingji Chen, Rujie He, Hao-Sen Chen, Yazheng Yang, Daining Fang
Ultra-broadband electromagnetic absorption materials and structures are increasingly attractive for their critical role in competing to the advanced broadband electromagnetic detective systems. Mechanically soft and weak wax-based materials composites are known to be insufficient to serve for practical electromagnetic absorption applications. To break through such barriers, here we developed an innovative strategy to enable the wax-based composites as robust and repairable meta-structures by employing a 3D printed polymeric patterned shell...
November 17, 2017: ACS Applied Materials & Interfaces
Yu-Ling Sun, Chao Shi, Wen Zhang
The organic-inorganic hybrid perovskite (H2hpz)[K(ClO4)3] (H2hpz = diprotonated homopiperazine) exhibits a distinct room-temperature dielectric transition. The dielectric switching at 303 K is associated with an order-disorder transition of the polar guest cation confined in the cage, corresponding to a dynamic change between motional and frozen states.
November 17, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
E Narsimha Rao, G Vaitheeswaran, Ali H Reshak, S Auluck
We explore the effect of spin-orbit interaction (SOI) on the electronic and optical properties of CsPbCO3F using the full potential linear augmented plane wave method with the density functional theory (DFT) approach. CsPbCO3F is known for its high powder second harmonic generation (SHG) coefficient (13.4 times (d36 = 0.39 pm V(-1)) that of KH2PO4 (KDP)). Calculations are done for many exchange correlation (XC) potentials. After the inclusion of SOI, the calculated Tran-Blaha modified Becke-Johnson (TB-mBJ) band gap of 5...
November 17, 2017: Physical Chemistry Chemical Physics: PCCP
K A Motovilov, M Savinov, E S Zhukova, A A Pronin, Z V Gagkaeva, V Grinenko, K V Sidoruk, T A Voeikova, P Yu Barzilovich, A K Grebenko, S V Lisovskii, V I Torgashev, P Bednyakov, J Pokorný, M Dressel, B P Gorshunov
The electrodynamics of metals is well understood within the Drude conductivity model; properties of insulators and semiconductors are governed by a gap in the electronic states. But there is a great variety of disordered materials that do not fall in these categories and still respond to external field in an amazingly uniform manner. At radiofrequencies delocalized charges yield a frequency-independent conductivity σ 1(ν) whose magnitude exponentially decreases while cooling. With increasing frequency, dispersionless conductivity starts to reveal a power-law dependence σ 1(ν)∝ν (s) with s < 1 caused by hopping charge carriers...
November 16, 2017: Scientific Reports
Morteza Gharib, Sean Mendoza, Moshe Rosenfeld, Masoud Beizai, Francisco J Alves Pereira
Saint Elmo's fire and lightning are two known forms of naturally occurring atmospheric pressure plasmas. As a technology, nonthermal plasmas are induced from artificially created electromagnetic or electrostatic fields. Here we report the observation of arguably a unique case of a naturally formed such plasma, created in air at room temperature without external electromagnetic action, by impinging a high-speed microjet of deionized water on a dielectric solid surface. We demonstrate that tribo-electrification from extreme and focused hydrodynamic shear is the driving mechanism for the generation of energetic free electrons...
November 16, 2017: Proceedings of the National Academy of Sciences of the United States of America
Ashish Kumar Mall, Ambesh Dixit, Ashish Garg, Rajeev Gupta
We report temperature dependent electron paramagnetic resonance (EPR) studies on polycrystalline YCrO3 samples at X-band (9.46 GHz) in the temperature range of 120 K-298 K. The EPR spectra exhibit a single broad line across the whole temperature range, attributed to Cr(3+) ions. The variation of EPR spectra parameters (line width, integrated intensity, and g-factor) as a function of temperature was analyzed to understand the nature of spin-dynamics in the paramagnetic region of YCrO3. A peak in the g-factor suggests the presence of a new phase within the paramagnetic state at an intermediate point of temperature T IP ~ 230 K, attributed to the onset of short range canted antiferromagnetic correlations in the material much above 140 K, Néel temperature (T N) of YCrO3...
November 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Mantu K Hudait, Michael Brian Clavel, Jheng-Sin Liu, Aheli Ghosh, Nikhil Jain, Robert J Bodnar
Due to the high carrier mobility of germanium (Ge) and high dielectric permittivity of amorphous niobium pentoxide (a-Nb2O5), Ge/a-Nb2O5 heterostructures offer several advantages for the rapidly developing field of oxide-semiconductor-based multifunctional devices. To this end, we investigation the growth, structural, band alignment, and metal-insulator-semiconductor (MIS) electrical properties of physical vapor deposited Nb2O5 on crystallographically oriented (100)Ge, (110), and (111)Ge epilayers. The as-deposited Nb2O5 dielectrics were found to be in the amorphous state, demonstrating an abrupt oxide/semiconductor heterointerface with respect to Ge, when examined via low- and high-magnification cross-sectional transmission electron microscopy...
November 16, 2017: ACS Applied Materials & Interfaces
Maria Letizia De Marco, Sanaa Semlali, Brian A Korgel, Philippe Barois, Glenna L Drisko, Cyril Aymonier
Metamaterials have optical properties that are unprecedented in nature. They have opened new horizons in light manipulation, with the ability to bend, focus, and completely reflect, transmit or absorb an incident wave front. Optically active metamaterials in particular could be used for applications ranging from 3D information storage, more efficient photovoltaic cells, high security watermarks, and fiber optics. Silicon (Si) particles are some of the most promising building blocks for optically active metamaterials, with high scattering efficiency coupled to low light absorption for visible frequencies...
November 16, 2017: Angewandte Chemie
Xueke Duan, Juanjuan Ren, Fan Zhang, He Hao, Guowei Lu, Qihuang Gong, Ying Gu
Combining the advantages of both gap surface plasmons and evanescent waves, we demonstrate simultaneously large Purcell enhancement and efficient one- dimensional collection of photons at subwavelength scale in the coupled nanowire- nanorod system. The spontaneous emission can be enhanced by thousands of times based on the excitation of gap surface plasmons with strongly localized electromagnetic field. Emitted photons are directly collected by subwavelength-confined evanescent modes and guided along the nanowire...
November 16, 2017: Nanotechnology
Tae-Ho Lee, Hyun-Gyu Hwang, Seonghoon Jang, Gunuk Wang, Seongbeom Han, Dong-Hwee Kim, Chong-Yun Kang, Sahn Nahm
Amorphous KNbO3 (KN) film containing KN nanocrystals was grown on TiN/SiO2/Si substrate at 350(o)C. This KN film showed a dielectric constant (εr) and piezoelectric strain constant (d33) of 43 and 80 pm/V at 10 V, respectively, owing to the existence of KN nanocrystals. Piezoelectric nanogenerators (PNGs) were fabricated using KN films grown on the TiN/Polyimide/PET substrates. PNG fabricated with the KN film grown at 350(o)C showed an open-circuit output voltage of 2.5 V and a short-circuit current of 70 nA...
November 16, 2017: ACS Applied Materials & Interfaces
Muhammad R A Qureshi, Yasir Alfadhl, Xiaodong Chen, Azadeh Peyman, Myron Maslanyj, Simon Mann
Human body exposure to radiofrequency electromagnetic waves emitted from smart meters was assessed using various exposure configurations. Specific energy absorption rate distributions were determined using three anatomically realistic human models. Each model was assigned with age- and frequency-dependent dielectric properties representing a collection of age groups. Generalized exposure conditions involving standing and sleeping postures were assessed for a home area network operating at 868 and 2,450 MHz...
November 16, 2017: Bioelectromagnetics
I Levin, V Krayzman, G Cibin, M G Tucker, M Eremenko, K Chapman, R L Paul
Perovskite potassium sodium niobates, K1-xNaxNbO3, are promising lead-free piezoelectrics. Their dielectric and piezoelectric characteristics peak near x = 0.5, but the reasons for such property enhancement remain unclear. We addressed this uncertainty by analyzing changes in the local and average structures across the x = 0.5 composition, which have been determined using simultaneous Reverse Monte Carlo fitting of neutron and X-ray total-scattering data, potassium EXAFS, and diffuse-scattering patterns in electron diffraction...
November 15, 2017: Scientific Reports
Nirvana B Caballero, Mariano Zuriaga, Josep Lluís Tamarit, Pablo Serra
The family of compounds CBrnCl4-n has been proven helpful in unraveling microscopic mechanisms responsible for glassy behavior. Some of the family members show translational ordered phases with minimal disorder which appears to reveal glassy features, thus deserving special attention in the search for universal glass anomalies. In this work, we studied CBrCl3 dynamics by performing extensive molecular dynamics simulations. Molecules of this compound perform reorientational discrete jumps, where the atoms exchange equivalent positions among each other revealing a cage-orientational jump motion fully comparable to the cage-rototranslational jump motion in supercooled liquids...
November 14, 2017: Journal of Chemical Physics
Alexandre P Dos Santos, Matheus Girotto, Yan Levin
We present an efficient approach for simulating Coulomb systems confined by planar polarizable surfaces. The method is based on the solution of the Poisson equation using periodic Green functions. It is shown that the electrostatic energy arising from the surface polarization can be decoupled from the energy due to the direct Coulomb interaction between the ions. This allows us to combine an efficient Ewald summation method, or any other fast method for summing over the replicas, with the polarization contribution calculated using Green function techniques...
November 14, 2017: Journal of Chemical Physics
Yusuke Nagasaki, Masafumi Suzuki, Junichi Takahara
An all-dielectric optical antenna supporting Mie resonances enables light confinement below the free-space diffraction limit. The Mie scattering wavelengths of the antenna depend on the structural geometry, which allows the antennas to be used for colored imprint images. However, there is still room for improving the spatial resolution, and new polarization-dependent color functionalities are highly desirable for realizing a wider color tuning range. Here, we show all-dielectric color printing by means of dual-color pixels with a subwavelength-scale resolution...
November 15, 2017: Nano Letters
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