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The exploration of novel ultrawide bandgap (UWBG) semiconductors is becoming a challenging and compelling research focus on semiconductor physics, materials, and device applications. Ternary B–C–N compounds have attracted much attention because their electronic structure and semiconductor properties are quite different depending on the chemical composition and atomic arrangement of boron, carbon, and nitrogen elements in the lattice. However, the lack of well-controlled high-quality B–C–N crystals has limited their potential as UWBG devices. In this study, B–C–N compounds are synthesized in bulks from graphite and hexagonal boron nitride (h-BN) using ball milling and high-pressure high temperature technique. The synthesized B–C–N compounds produced are highly crystallized layered-materials with intercalated graphene layers in C-doped h-BN layers. The doped carbon atoms occupy boron sites and nitrogen sites of the h-BN layers unbalanced, giving rise to the n-type conductivity of the B-C-N layered compounds. The measured optical bandgaps range from 3.4 to 6.0 eV, which can be regulated by the carbon content. Their electronic properties are also tunable. Our work is expected to initiate potential applications of the B–C–N material as UWBG semiconductors.

Ceramic-based capacitors with excellent recoverable energy storage density (Wrec) and efficiency (η) are greatly desired for pulsed capacitors but challenge as well. In this work, the high energy storage performance with an Wrec of 5.1 J/cm3, an η of 93.4%, and an ultrafast discharge–charge speed t0.9 of 72 ns is achieved in unusual interstitial and substitutional hybrid solid solution of Sr0.64Bi0.18Na0.18TiO3-ZnO (SBNT-Zn), in which two Zn2+ ions occupy one A-site, while one Zn2+ ion occupies one B-site of ABO3 perovskite lattice simultaneously. The addition of Zn2+ increases lattice distortion and breaks long-range ferroelectric order, resulting in more highly dynamic polar nanoregions, higher relaxation behaviors as well as larger polarization (ΔP). Moreover, the extraordinary hybrid solid solution configuration enhances the bandgap of SBNT-Zn and ZnO as a sintering aid refines grain size, both help to enhance electric breakdown strength. This work affirms the feasibility and reliability of forming a hybrid solid solution to develop high-performance ferroelectric materials.

The progress in efficiency improvements of blade-coated two-dimensional perovskite solar cells (PSCs) lags behind that of spin-coated ones. Pinholes and voids are two important structural defects hiding in blade-coated large-area perovskite films to deteriorate device efficiency and stability. However, the formation of pinholes and voids is still difficult to predict. On substrates with moderate wettability, Dion–Jacobson perovskite films can be blade-coated with good coverage, but we highlight that the formation of nanoscale voids buried at the bottom side of perovskite films can occur frequently, depending critically on the wettability of substrates. It is revealed that super hydrophilic NiOx substrates with contact angle θ < 5° possesses strong bubble repellent property, which thermal dynamically prevents the retraction of precursor solution and plays an important role to suppress the attachment and growth of bubbles on its surface. The probabilities of forming both pinholes and buried voids in perovskite films on super hydrophilic NiOx substrates are one order of magnitude lower than that on hydrophilic PTAA and poly-TPD substrates. The blade-coated (BDA)MA4Pb5I16 films on NiOx substrate offer PSCs with excellent interfacial hole extraction and reduced leakage current, contributing a significant power conversion efficiency improvement from ∼10% to 16.26%.

The domain reversal dynamics of rhombohedral and tetragonal PIN–PMN–PT ferroelectric single crystals has been investigated by analyzing the variation of hysteresis loops under various electric fields and frequencies. As the electric field amplitude E0 continuously increases, the hysteresis area ⟨A⟩ clearly reflects three stages of polarization reversal. The complete scaling relations of domain reversal dynamics were determined. For rhombohedral PIN–47PMN–29PT crystals, the dynamic hysteresis area follows the law of ⟨A⟩ ∝ f −0.38816E05.21244 in the first E0-stage and ⟨A⟩ ∝ f 0.03553E00.37126 in the third E0-stage. For tetragonal PIN–37PMN–39PT crystals, the dynamic hysteresis area follows the law of ⟨A⟩ ∝ f −0.09054E02.74854 in the first E0-stage and ⟨A⟩ ∝ f −0.15504E02.06936 in the third E0-stage. The negative α indicates that with the alternating velocity of the increasing periodic electric field, more and more domain reversals fail to follow with the alternating electric field. However, rhombohedral PIN–47PMN–29PT crystals possess a positive α in the third E0-stage, indicating that 71° and 109° domains can keep pace with varying E0 more easily. The positive β indicates that when the electric field frequency is fixed, more and more domains begin to reverse with the intensity of the increasing electric field. In addition, the function of ⟨A⟩ ∝ f αE0β cannot be applied to the second E0-stage, where the non-180° domain rotation starts occurring but 180° domain rotation has not finished yet.

Transparent polycrystalline ceramics exhibit improved mechanical and optical properties. However, synthesizing transparent ceramics without additives is nontrivial. Herein, we report the synthesis of two transparent ceramics (β-Si3N4 and γ-Si3N4) under high pressure and high temperature from a pure Si3N4 precursor with nano-/micro-dual grain sizes. Synthesized β-Si3N4 exhibited a significantly enhanced Vickers hardness reaching 24.2 GPa (at 10 N load) when transparency was achieved. Transparent nano-grained γ-Si3N4 exhibited a Vickers hardness of 37.3 GPa. These are the highest hardness values reported for these two phases at a 10 N load. Density and microstructure measurements suggest that the hardness and transparency of the specimens correlate with both the grain size and porosity/density. The negligible amount of pores accounts for the superior optical transparency and high hardness of two Si3N4 allotropes. As higher pressures can effectively suppress grain growth and minimize pores between grains, high-pressure sintering is demonstrated as an effective way to realize highly dense transparent ceramics.

A vertical flux of heat can bring about hybrid generation of charge and spin currents and eventually convert into the transverse electric voltage in the bilayers composed of metallic magnet and non-magnetic heavy metal (HM). We identified the thermoelectric effects in the sputter-deposited metallic film of CsCl-ordered FeRh/HM throughout its metamagnetic transition from ferromagnetic (FM) to antiferromagnetic (AFM) phase. With the employment of different HMs (Pt, Au) as the spin detective layers, we found that the FM phase allows for hybrid generation of charge and spin currents by heat, respectively, attributed to the anomalous Nernst effect (ANE) and the spin Seebeck effect (SSE), while the AFM phase merely retains the ANE from residual nanoscale FM domains at cryogenic temperatures, which was further confirmed by the control measurement based on the adjustment of spin Hall angle for W during its β to α phase transition. Contribution from the proximity-induced ANE of HM was verified to be negligible compared with that of ANE and SSE of FeRh. Our method opens up more access to quantitatively discern the entangled thermo-charge/spin contributions in metallic magnets, and the combination of thermoelectric effects with metamagnetic phase transition gives impetus to exploiting more versatile and energy-saving thermo-spin logic applications.

Recent demonstration of the interfacial Dzyaloshinskii-Moriya interaction (DMI) between a heavy metal and a magnetic insulator provides the possibility to manipulate chiral spin textures in the magnetic insulator for the extremely low power consumption devices. However, the origin and strength of the interfacial DMI remain in dispute in this system. We used the electrical transport measurements to determine the DMI strength to be ∼0.040 pJ/m at room temperature in Pt/Tm3Fe5O12 (TmIG) bilayers. The TmIG saturation magnetization and DMI strength exhibit different temperature dependences, which is attributed to the DMI being mainly contributed by Fe ions instead of Tm ions. With a Cu layer inserted between Pt and TmIG, the DMI strength is reduced to ∼0.012 pJ/m and the topological Hall effect vanishes, strongly suggesting that the Pt/TmIG interface has important contribution to the DMI.

We report an ultrathin and durable open metamaterial capable of both fluid passage and noise insulation at low frequencies. The proposed open metamaterial, denoted as the perforated and constrained acoustic metamaterial (PCAM), contains a large orifice in each unit cell. An impedance-based model was established to investigate the working mechanism and acoustic performances of the PCAM and was then verified by measurements in a sound impedance tube. With only a thickness of 1.5 mm (0.19% of wavelength), a PCAM sample exhibits a sound transmission loss of 20 dB at 430 Hz. This high-efficiency soundproof feature under the ventilation condition is attributed to the interferences of the two wave fields between the orifice area and the plate area in the near-field. The PCAM may have potential applications in limited spaces requiring high-efficiency ventilation and long-time service.

A gullwing-structural piezoelectric energy harvester mainly consisting of two typical nonlinear buckled-bridges is proposed to effectively scavenge low-frequency rotational kinetic energy based on a gear mechanism induced interwell oscillation. A natural buckled piezoelectric unit and a flexible polymer substrate are used for the buckled-bridge. A thinned bulk lead zirconate titanate ceramic is employed for the piezoelectric layer in consideration of its excellent electromechanical factor. The presented harvester can generate a peak open-circuit voltage of 20 V at a rotational frequency of 7.8 Hz, which has a low dependence on the applied frequency. A 100 μF capacitor reaches a charging voltage of 14.7 V after 38 s and is saturated at 16.05 V for 122 s. Through the power management circuit, the harvester generates an output power of 0.4 mW and the effective power density of 6.54 μW mm−3 at the low rotational frequency. These results indicate that this strategy is promising for self-powered sensors, especially at changeable and low-frequency ambient, such as tire pressure monitoring.

Materials with an electrocaloric effect (ECE) have been extensively studied for their cooling applications. Most ECE films are oriented and are difficult to integrate into industrial production processes. Here, an ECE (ΔS = 4.48 J K−1 kg−1 and ΔT = 6.4 °C at ΔE = 390 kV cm−1) is obtained in an unoriented PbZr0.95Ti0.05O3 (PZT) film fabricated on an FTO substrate using an improved sol-gel method. To improve the ECE, Si-doped PZT films with 1–4 mol. % of Si are deposited. X-ray diffraction and X-ray photoelectron spectroscopy results confirm that Si was doped into the PZT lattice. The orthorhombic and tetragonal antiferroelectric phases coexist in the PZT/0.01 Si film. A large ECE (ΔS = 5.89 J K−1 kg−1 and ΔT = 8.5 °C at ΔE = 390 kV cm−1) is acquired in the PZT/0.01 Si film, which was measured by an indirect method. This work demonstrates that ECE of unoriented PZT antiferroelectric films on FTO substrates can be improved by a certain amount of Si doping.

A piezoelectric vibration energy harvester with a broad bandwidth (>15 Hz) is proposed based on a flexible self-buckled bridge. The polymer sheet, thin metal foil, and thinned piezoelectric ceramic film are bonded to constitute the flexible buckled bridge with the total thickness of 200 μm. Its good flexibility is benefit to obtain low resonant frequency ( 15 Hz) is proposed based on a flexible self-buckled bridge. The polymer sheet, thin metal foil, and thinned piezoelectric ceramic film are bonded to constitute the flexible buckled bridge with the total thickness of 200 μm. Its good flexibility is benefit to obtain low resonant frequency (

HfOxNy thin films were deposited on polished and oxidized silicon wafers at different nitrogen-oxygen gas flow rates by DC magnetron reactive sputtering, and temperature sensors based on these HfOxNy thin films were fabricated using a microelectromechanical system micromachining process. The resistance–temperature dependencies of these sensors were studied in the temperature range of 4.2 K–300 K, and the effect of the sputtering gas flow rate on the initial resistivity and sensitivity [temperature coefficient of resistance and absolute sensitivity (Sa)] was discussed. One of these sensors was subjected to 15 cycles between 300 K and 4.2 K for thermal cycle stability testing. The performances of these sensors were compared to the now available negative temperature coefficient thin film temperature sensors (ZrNx, CrNx, RuO2, and ZrOxNy), and they show very outstanding sensitivity and thermal cycle stability. Furthermore, the conduction mechanism of HfOxNy thin films in the cryogenic region was studied for the first time.

Non-reciprocal devices such as isolators and circulators, based mainly on ferromagnetic materials, require extremely low dielectric loss in order for strict power-link budgets to be met for millimetre (mm)-wave and terahertz (THz) systems. The dielectric loss of commercial SrFe12O19 hexaferrite was significantly reduced to below 0.002 in the 75–170 GHz band by thermal annealing. While the overall concentration of Fe2+ and oxygen vacancy defects is relatively low in the solid, their concentration at the surface is significantly higher, allowing for a surface sensitive technique such as XPS to monitor the Fe3+/Fe2+ redox reaction. Oxidation of Fe2+ and a decrease in oxygen vacancies are found at the surface on annealing, which are reflected in the bulk sample by a small change in the unit cell volume. The significant decrease in the dielectric loss property can be attributed to the decreased concentration of charged defects such as Fe2+ and oxygen vacancies through the annealing process, which demonstrated that thermal annealing could be effective in improving the dielectric performance of ferromagnetic materials for various applications.Non-reciprocal devices such as isolators and circulators, based mainly on ferromagnetic materials, require extremely low dielectric loss in order for strict power-link budgets to be met for millimetre (mm)-wave and terahertz (THz) systems. The dielectric loss of commercial SrFe12O19 hexaferrite was significantly reduced to below 0.002 in the 75–170 GHz band by thermal annealing. While the overall concentration of Fe2+ and oxygen vacancy defects is relatively low in the solid, their concentration at the surface is significantly higher, allowing for a surface sensitive technique such as XPS to monitor the Fe3+/Fe2+ redox reaction. Oxidation of Fe2+ and a decrease in oxygen vacancies are found at the surface on annealing, which are reflected in the bulk sample by a small change in the unit cell volume. The significant decrease in the dielectric loss property can be attributed to the decreased concentration of charged defects such as Fe2+ and oxygen vacancies through the annealing process, which demonstrated ...

Extrinsic contributions play an important role in the functionalities of ferroelectric materials, while domain structure evolution is crucial for understanding the extrinsic dielectric and piezoelectric responses. In this work, domain configuration changes with an electric field applied along [001]C in the tetragonal (K, Na, Li)(Nb, Sb, Ta)O3 single crystal were studied by means of polarizing light microscopy. Results show that parts of the spontaneous polarizations in the (001)C plane are switched to [001]C direction, while others still stay in the (001)C plane due to high induced internal stresses. Single domain state cannot be achieved even under a high electric field. After being poled along [001]C, the volume fraction of domains with polarzations in the (001)C plane is still about 25.2%. The extrinsic contributions to the dielectric constant are 15.7% and 27.2% under the E field of 1 kV/cm and under 2 kV/cm, respectively, estimated by the Rayleigh analysis.

A Li and Ta modified (K, Na)NbO3 lead-free single crystal with a large size (13 × 10 × 20 mm3) has been grown by using the top-seeded solution growth method. The large size allows us to carry out an extensive study on this tetragonal crystal. We have measured a complete set of elastic, dielectric, and piezoelectric constants for the [001]C poled crystal with the single domain state. The crystal exhibits high shear piezoelectricity with d15 = 518 pC/N and k15 = 0.733, showing excellent potential in shear electro-sonic energy transformation devices. It is found that the high shear piezoelectricity originates from the vicinity of orthorhombic-tetragonal phase transition, which favors polarization rotation greatly. The orientation dependence of longitudinal dielectric, piezoelectric, and elastic constants and electromechanical coupling factor in the 3-dimentional space were calculated based on the single domain dataset. We believe that this work is of great importance for both fundamental studies and device d...

This letter presents a high performance bimorph piezoelectric MEMS harvester with bulk PZT thick films on both sides of a flexible thin beryllium-bronze substrate via bonding and thinning technologies. The upper and lower PZT layers are thinned down to about 53 μm and 76 μm, respectively, and a commercial beryllium bronze with the thickness of about 50 μm is used as the substrate. The effective volume of this device is 30.6 mm3. The harvester with a tungsten proof mass generated the close-circuit peak-to-peak voltage of 53.1 V, the output power of 0.979 mW, and the power density of 31.99 mW/cm3 with the matching load resistance of 360 kΩ at the applied acceleration amplitude of 3.5 g and the applied frequency of 77.2 Hz. Meanwhile, in order to evaluate the stability, the device was measured continuously under applied acceleration amplitudes of 1.0 g and 3.5 g for one hour and demonstrated a good stability. Then, the harvester was utilized to light up LEDs and about twenty-one serial LEDs were lighted up a...

This paper presents a tunable and flexible metamaterial with double split-ring resonators arrays fabricated on parylene-C substrates. We numerically and experimentally designed four structures with different angles between the outer and inner split-ring resonators to achieve tunability of the multiband metamaterials and investigated the effect of polarization and incident angle direction of terahertz waves on the transmission spectra of metamaterials. The results show that the first resonant frequency increases slightly when the inner rings rotate, which realizes frequency modulation. The polarization study of the structure indicated that it might be applied as a dual-band amplitude modulation device. Finite-difference time-domain numerical simulations were further conducted to calculate the electromagnetic field as well as surface current distributions at the resonant frequencies. It demonstrated that the two resonant dips are caused by different mechanisms.

Lanthanide ions possess fascinating optical properties and have received great attention due to their widespread technological applications. However, enhancing and in-situ tuning the photoluminescence is still a challenging subject. The paper shows that in 0–3 type lead-free ferroelectric composites constructed by ZnO and 1.0 mol. % Er-doped 0.94Bi0.5Na0.5TiO3-0.06BaTiO3, the up-conversion photoluminescence of Er3+ ion can be unusually increased by 4.5 times after introducing 40 mol. % ZnO, and then further enhanced by 1.2 times with electrical poling. The mechanism is attributed to the ZnO-mediated energy transfer and the electric field-induced phase transition. The composites also show excellent electrical properties and improved temperature stability. These results not only provide a hybrid method to significantly enhance and in-situ tune the photoluminescence but also are helpful for developing multifunctional materials with excellent optical and electrical properties simultaneously.

The crystalline phases and domain configuration in the morphotropic phase boundary composition Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 (PMN-0.34PT) single crystal have been investigated by synchrotron-based X-ray 3D Reciprocal Space Mapping (3D-RSM) and Piezoresponse Force Microscopy. The coexistence of tetragonal (T) and monoclinic MC phases in this PMN-0.34PT single crystal is confirmed. The affiliation of each diffraction spot in the 3D-RSM was identified with the assistance of qualitative simulation. Most importantly, the twinning structure between different domains in such a mixed phase PMN-PT crystal is firmly clarified, and the spatial distribution of different twin domains is demonstrated. In addition, the lattice parameters of T and MC phases in PMN-0.34PT single crystal as well as the tilting angles of crystal lattices caused by the interfacial lattice mismatch are determined.

Optical temperature sensing based on the variation of the fluorescence intensity ratio of rare-earth materials has become appealing due to the multiple superiorities over the electrical temperature sensing. However, confined by the largest energy separation of two thermally linked levels of rare-earth ions, the highest sensitivity of such temperature sensing is essentially smaller than 2878/T2, as reported previously from diverse systems. In this work, we demonstrate that ultrahigh-sensitive temperature sensing can be achieved from Pr3+-doped (K0.5Na0.5)NbO3 based on the intensity ratio of the 1D2-3H4 emission to the 3P0-3H4 emission. The ratio can be increased as high as 18-fold when temperature rises from room temperature to 456 K, nicely fitting a thermally linked-levels-like equation and showing an ultrahigh sensitivity of 7997/T2. The striking change of the ratio is attributed to the interaction between the two emission levels and the intervalence charge transfer state. This work may have provided a ...

[001] oriented relaxor based ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) ceramics were fabricated by templated grain growth. The effects of BaTiO3 template amount on the [001] orientation degree, microstructure, and resulting changes in dielectric, piezoelectric, and ferroelectric properties of PIN-PMN-PT were investigated. A high [001] texture fraction of 93% was achieved in the PIN-PMN-PT ceramics at 5 vol. % BaTiO3 template. Giant electromechanical properties (d33* = 1555 pC/N, d33 = 824 pC/N, and kp = 0.81) and high ferroelectric properties (Ec = 8.3 kV/cm and Pr = 31 μC/cm2) were obtained from those highly textured ceramics, which are much superior to those of randomly oriented counterpart. Furthermore, the textured ternary ceramics exhibited remarkably improved phase transition temperatures (Tr-t = 120 °C and Tc = 203 °C) compared with previously reported binary PMN-PT textured ceramics. The domain structure was characterized by piezoelectric force microscopy, and domain contributi...

Extrinsic contributions play an important role in the functionalities of ferroelectric materials, while domain structure evolution is crucial for understanding the extrinsic dielectric and piezoelectric responses. In this work, domain configuration changes with an electric field applied along [001]C in the tetragonal (K, Na, Li)(Nb, Sb, Ta)O3 single crystal were studied by means of polarizing light microscopy. Results show that parts of the spontaneous polarizations in the (001)C plane are switched to [001]C direction, while others still stay in the (001)C plane due to high induced internal stresses. Single domain state cannot be achieved even under a high electric field. After being poled along [001]C, the volume fraction of domains with polarzations in the (001)C plane is still about 25.2%. The extrinsic contributions to the dielectric constant are 15.7% and 27.2% under the E field of 1 kV/cm and under 2 kV/cm, respectively, estimated by the Rayleigh analysis.

Polymer optical fibers have received much attention in recent years as they can replace silica glass fibers in local area nets in the future. A neodymium ion (Nd3+)-doped poly(methyl methacrylate) (PMMA) fiber has been made from Nd3+ containing PMMA as a core and silica resin as claddings. Fluorescence of the fiber results from the transition of 4G5/2 to 4I9/2 in a three energy level system. Amplified spontaneous emission (ASE) at 575 nm has also been observed and the critical power at a pump wavelength of 514.5 nm for the onset of ASE has been found to be 85 mW.

The growth of highly strained InxGa1−xAs (x≳0.25) epilayer on GaAs (001) undergoes a two‐dimensional–three‐dimensional (2D‐3D) growth mode transition beyond a critical thickness which depends on the strain. We show that the growth mode is controlled by the island‐edge diffusion carrier which originates from elastic energy relaxation at the edge of 2D island. The 2D‐3D growth mode transition depends upon whether or not a new layer nucleates on top of the island of 2 ML height before coalescence. The In atoms on the surface arising from surface segregation affect the island‐edge diffusion barrier and nucleation, leading to a 3D growth mode at the critical thickness. The experimental investigation is explained satisfactorily.

We have studied the influence of interface roughness scattering on the mobility of two‐dimensional electron gas (2DEG) in GaAs–AlGaAs modulation‐doped heterostructures (MDH) both experimentally and theoretically. When the background ionized impurity concentration in the GaAs layer is smaller than 2.5×1015 cm−3, our investigation shows that interface roughness scattering is the dominant scattering mechanism in the high 2DEG density (Ns≥5×1011 cm−2) GaAs–AlGaAs MDH. We also demonstrate that interface roughness scattering is about an order of magnitude stronger than alloy disorder scattering in GaAs–AlGaAs MDH if the AlGaAs/GaAs interface fluctuation is only one monolayer of GaAs.

(1−x)(Bi0.5Na0.5)TiO3-xBa(Zr0.055Ti0.945)O3 (0 ≤ x ≤ 0.12) lead-free ceramics have been prepared and the morphotropic phase boundary (MPB) is confirmed to be x = 0.06–0.09. The MPB composition x = 0.07 shows enhanced pyroelectric properties from room temperature (RT) to the depolarization temperature Td (87 °C), with the pyroelectric coefficient p = 0.057 μC/cm2 °C and the figures of merit Fi = 203 pm/V, Fv = 0.022 m2/C, and Fd = 10.5 μPa−1/2 at RT and the highest pyroelectric coefficient of 2.21 μC/cm2 °C near Td. These values are superior to other lead-based/lead-free pyroelectric ceramics. Enhanced pyroelectric properties can be explained by the effects of MPB and ferroelectric-antiferroelectric phase transition.

Lead-free piezoelectric single crystal 0.95(Na0.5Bi0.5)TiO3 (NBT)-0.05BaTiO3 was grown by top-seeded solution growth method, which has rhombohedral symmetry with composition near morphotropic phase boundary. Full set of dielectric, piezoelectric, and elastic constants for [001]c poled domain-engineered single crystal was determined. Excellent electromechanical properties and low dielectric loss (d33 = 360 pC/N, d31 = −113 pC/N, d15 = 162 pC/N, k33 = 0.720, kt = 0.540, and tan δ = 1.1%) make it a good candidate to replace lead-based piezoelectric materials. The depolarization temperature (Td = 135 °C) is the highest among all NBT-based materials and its electromechanical coupling properties are very stable below Td. Extrinsic contributions to piezoelectric properties were investigated by Rayleigh analysis.

We investigate the spin-dependent Fano resonance in an impurity-doped graphene sheet coupled to ferromagnetic (FM) leads at low temperatures. By the nonequilibrium Green's function theory, we calculate the linear conductance of the system, which possesses a different Fano structure both in the parallel and anti-parallel configuration of the FM leads. The results come from the quantum interference between resonant and nonresonant processes in the system. Our studies indicate that the system is an ideal platform to investigate the Fano physics, even in some relevant experiments.

An effective cathode consisting of samarium (Sm) doped aluminum (Al) layer and a pure Al layer is reported for application in organic photovoltaic cells (OPVs). Standard copper phthalocyanine (CuPc)/C60 OPVs using this bilayer cathode show dramatically increased short-circuit current density and power conversion efficiency, which are 64% increased by employing a appropriate ratio of 1:3 of Sm:Al layer as compared with that of control devices with pure Al cathode. The photoelectric properties reveal that the improved efficiency is mainly related to the balance of the enhanced electron collection ability and the optimized optical reflection of a Sm doped Al layer.

A piezoelectric generator with nonlinear spring oscillator is proposed to provide multiple resonant modes for operation and improve conversion efficiency. In order to scavenge the vibration energy of multiple frequencies from a certain vibration source, two types of nonlinear springs have been employed and tested. The maximum output power of 5, 17.83, and 23.39 μW for the nonlinear spring of 8.3 N/m with 1 g acceleration has been obtained under the resonant frequency of 89, 104, and 130 Hz, respectively. Its total output power of 46.22 μW is obviously larger than the one of 28.35 μW for traditional second-order spring-mass linear system.

Heterostructures were fabricated by growing Pr0.6Ca0.4MnO3 (PCMO) films on Pb(Mg1/3Nb2/3)0.7Ti0.3O3 substrates. It was shown that the magnetizations of the samples can be tuned dramatically by electric fields via piezostrain and the effect is dominated by the change in phase separation. More interestingly, the electric-field control of magnetization is nonvolatile, manifesting a memory effect of strain. The results were discussed by considering the effect of electric-field-induced strain on the energy landscape of PCMO and the resultant change in phase separation. This work is helpful for exploring the evolution of phase separation with well-controlled strains and the magnetoelectric coupling effect.

This letter reports on a process scheme to obtain highly reproducible Ni1−xPtx silicide films of 3–6 nm thickness formed on a Si(100) substrate. Such ultrathin silicide films are readily attained by sputter deposition of metal films, metal stripping in wet chemicals, and final silicidation by rapid thermal processing. This process sequence warrants an invariant amount of metal intermixed with Si in the substrate surface region independent of the initial metal thickness, thereby leading to a self-limiting formation of ultrathin silicide films. The crystallographic structure, thickness, uniformity, and morphological stability of the final silicide films depend sensitively on the initial Pt fraction.

Phase diagram of Bi0.5Na0.5TiO3–BaTiO3–K0.5Na0.5NbO3 ternary system has been analyzed and (0.94−x)BNT–0.06BT–xKNN (0.15≤x≤0.30) ceramics have been prepared and investigated. Pseudocubic structures were confirmed by x-ray diffractions and its preliminary Rietveld refinements. P-E, S-E, and S-P2 profiles (where P, E, and S denote polarization, electric field, and strain, respectively) indicate electrostrictive behavior of all ceramics. The compositions with x=0.20 and 0.25 show pure electrostrictive characteristics. The dissipation energy, electrostrictive strain, and electrostrictive coefficient have been determined and compared with other lead-free and lead-containing electrostrictors. The electrostrictive coefficient can reach as high as 0.026 m4/C2, about 1.5 times of the value of traditional Pb-based electrostrictors.

Resistive switching devices with a sandwich structure Ag∕(AgI)0.5(AgPO3)0.5∕Pt were fabricated on silicon(001) wafer by using the pulsed laser deposition method and the focused ion beam nanofabrication technique. (AgI)0.5(AgPO3)0.5 films deposited at room temperature show a nanocrystal structure and the composition of the films was identified by using x-ray photoelectron spectroscopy. The current-voltage characteristics of the Ag∕(AgI)0.5(AgPO3)0.5∕Pt memory units show good switching behaviors. The ratio of the conductance between the “ON” state (high conductance) and the “off” state (low conductance) reaches 1×106. The ON and OFF states can be effectively written, read, and erased up to 4×105 scanning cycles by using a set of voltage pulses with an amplitude less than 3V. It also could be observed that the time for the writing and erasing operations could be less than 150ns. The switching mechanism of the Ag∕(AgI)0.5(AgPO3)0.5∕Pt memory devices was ascribed to the possible formation and dissolution of Ag...

We demonstrate a way to direct carbon nanotube growth using Si nanocrystals that are self-ordered via the thermal decomposition of thin silicon-on-insulator substrates. The Si nanocrystals are about 90nm wide and 100–150nm tall, with 200nm spacing. Nanotubes connect the silicon nanocrystals to form a network. Nanotubes selectively appear between tops of the Si nanocrystals. We show that the flow pattern of the carbon feedstock in the chemical vapor deposition growth process is disturbed by the geometric effect of the Si nanocrystals, providing a mechanism for growth between the tops of the Si nanocrystals.

We demonstrate the new features of a polyurethane shape memory polymer: water-driven actuation and recovery in sequence (i.e., programmable). Hydrogen bonding is identified as the reason behind these features. In addition, the absorbed water is quantitatively separated into two parts, namely, the free water and bound water. Their individual contribution on the glass transition temperature is identified.