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The direct current potential drop (DCPD) method is an important method for monitoring crack initiation and propagation in specimens. During fatigue crack growth monitoring, the load causes the potential drop (PD) signal to change and produces periodic fluctuations independent of crack growth, thereby affecting the measurement accuracy and resolution. This study proposes a novel calibration method to quantitatively evaluate and correct the measurement error due to the change in the PD signal caused by the load during fatigue crack growth monitoring. Tensile fatigue tests and DCPD monitoring tests were conducted to measure the PD signal fluctuation owing to the cyclic load before and after specimen cracking. Electrical–structural finite element analyses were used to simulate the test process, and a calibration function considering the influence of the load was obtained. The influence of the load on the measurement accuracy and resolution was quantitatively evaluated using the model and experimental data. The cyclic load caused the PD signal to deviate from the calibration curve when the deformation of the specimen was not considered; the PD signal exhibited periodic fluctuations as a result. Moreover, for a certain range of fatigue loads, the corresponding PD signal increased as the crack grew. The proposed calibration method can correct the measurement error due to cyclic load, thereby further improving the measurement accuracy and resolution, and providing a basis for high-precision crack growth measurement.

The direct current potential drop (DCPD) method is widely used in laboratory environments to monitor the crack initiation and propagation of specimens. In this study, an anti-interference signal processing approach, combining wavelet threshold denoising and a variable current amplitude DCPD signal synthesis technique, was proposed. Adaptive wavelet threshold denoising using Stein’s unbiased risk estimate was applied to the main potential drop signal and the reference potential signal under two different current amplitudes to reduce the interference caused by noise. Thereafter, noise-reduced signals were synthesized to eliminate the time-varying thermal electromotive force. The multiplicative interference signal was eliminated by normalizing the main potential drop signal and the reference potential drop signal. This signal processing approach was applied to the crack growth monitoring data of 316 L stainless steel compact tension specimens in a laboratory environment, and the signal processing results of static cracks and propagation cracks under different load conditions were analyzed. The results showed that the proposed approach can significantly improve the signal-to-noise ratio as well as the accuracy and resolution of the crack growth measurement.

Cemented coal gangue-fly ash backfill (CGFB) mixtures are utilized as the filling materials for backfilling the underground openings in coal mines. The freshly prepared CGFB slurries are commonly transported into the gobs through a pipeline. The mixture ratio of slurry concentration and suspending agent (HPMC) plays an essential role in transporting the slurry to goaf smoothly and efficiently. In this paper, the influence of slurry concentration and HPMC on the performance of coal gangue-fly ash cemented filling material was studied based on the response surface method. The prediction model of CGFB slurry slump flow, segregation rate, and bleeding rate was constructed. It is concluded that the segregation rate and slump flow of slurry are more sensitive to the variation of concentration. On the other hand, the bleeding rate of slurry is more sensitive to the change of HPMC content. Based on the established model, the reasonable mix proportion range of slurry concentration and suspending agent (HPMC) was obtained. In addition, three new CGFB mixtures have been tested, and the experimental results are in good agreement with the predicted values.

This article proposes an integrated high-sensitivity temperature sensor based on SiO2-asymmetric Mach–Zehnder interferometer (AMZI) and thermal-expansion-induced stress of aluminum-SiO2. Mechanical analysis of this structure is carried out. The result shows that the SiO2 chip is compressed, and the waveguide length is decreased, leading to the central wavelength shift of the sensor. The sensitivity of the sensor can be customized by different arm lengths of the AMZI. The chip is fabricated using a standard planar lightwave circuit (PLC), and the aluminum alloy plate is glued to the chip using $\alpha $ -cyanaloc acrylic resin adhesive. The sensitivities of two sensors with different arm lengths are tested. The test results show the sensitivity reaches 6.86 and 54.2 nm $\cdot \text{K}^{-1}$ , respectively, which coincides with the theoretical analysis. With low cost and customizable sensitivity, this new device is applicable in many fields.

NbCoSb, nominally a 19-electron half-Heusler (19-HH) compound, is one of the emerging novel thermoelectric (TE) materials and has attracted much attention in recent years. By introducing a large am...

It is importance to understand the accurate material mechanical property of local area with flaws in the structure integrity evaluation, and the plastic hardening induced by the welding or other processing would induce the change of the mechanical property of the local area in structures. To understand and obtain heterogeneous material mechanical properties in the welded joint or other local region in the core structure of nuclear power plants, a group tests of tensile work hardening and continuous ball indentation, combining with inversion analysis by using the finite element method, are used to obtain the local mechanical properties of nuclear grade 316L austenitic stainless steel, and an approach to obtain the stress–strain relationship of the stainless steel material during the plastic deformation stage under different elongations is developed based on the representative stress–strain method in this paper. The investigated results indicates that the related mechanical parameters of 316L austenitic stainless steel increase with different elongations, and the deviations of the yield strength and the tensile strength values are both within 6%. It provides a reasonable and effective method to obtain the actual material mechanical property of the local area in important structures.

Environmentally assisted cracking (EAC) is a main failure mode of key structural materials of nuclear power pressure vessels and pipelines in service. The key structural materials of nuclear power will undergo plastic deformation due to cold working during manufacturing, assembly and welding, and cold working will affect the EAC crack growth rate. In order to understand effect of cold working on crack growth rate of EAC, a combination of theory, experiment and finite element simulation is used. There are experiments to obtain the mechanical properties of 316L stainless steel at different degrees of cold working, and the creep characteristics of 316L stainless steel at low temperature and high stress were obtained by experiment. Based on experiment and theoretical analysis, creep rate of crack tip is used to replace strain rate of crack tip in Ford-Andresen model, and effect of cold working on crack growth rate of EAC is analyzed with hardening at crack tip and without hardening at crack tip. The results show that cold working accelerates crack growth rate of EAC, and the hardening of crack tip micro zone restrains crack growth rate of EAC, causing the “hysteresis” phenomenon in the EAC crack growth process. It is more reasonable to use creep rate of crack tip instead of strain rate of crack tip to calculate crack growth rate of EAC.

Dissimilar metal welded joints (DMWJs) possess significant localized mechanical heterogeneity. Using finite element software ABAQUS with the User-defined Material (UMAT) subroutine, this study proposed a constitutive equation that may be used to express the heterogeneous mechanical properties of the heat-affected and fusion zones at the interfaces in DMWJs. By eliminating sudden stress changes at the material interfaces, the proposed approach provides a more realistic and accurate characterization of the mechanical heterogeneity in the local regions of DMWJs than existing methods. As such, the proposed approach enables the structural integrity of DMWJs to be analyzed in greater detail.

Lithium metal batteries are a promising candidate for future high-energy-density energy storage. However, dendrite growth and the high reactivity of the Li metal anode result in low cycling efficiency and severe safety concerns. Here, we present a strategy to stabilize the lithium metal anode through cation doping in Li7La3Zr2O12 (LLZOM, M = dopant). High-throughput automated reaction screening together with a machine learning approach are developed to evaluate possible reactions and the thermodynamic stability of the Li|LLZOM interfaces under various chemical conditions. It is discovered that some dopants, such as M = Sc3+ (doping on Zr site), Ce3+ (La or Zr), Ac3+ (La), Y3+ (La or Zr), Tm3+ (La or Zr), Er3+ (La or Zr), Ho3+ (La or Zr), Dy3+ (La or Zr), Nd3+ (La or Zr), Tb3+ (La or Zr), Pr3+ (La), Pm3+ (La or Zr), Sm3+ (La or Zr), Gd3+ (La or Zr), Lu3+ (La), Ce4+ (Zr), Th4+ (Zr), and Pa5+ (Zr), exhibit thermodynamic stability against Li; while others, M = Ca2+ (La or Zr), Yb3+ (La), Br3+ (Li), Te4+ (Zr), Se4+ (Zr), S4+ (Zr), Hf4+ (Zr), Cl5+ (Zr), and I5+ (Zr), may lead to the spontaneous formation of a stable, passivating solid electrolyte interphase (SEI) layer on the Li metal, and alleviate dendritic lithium growth. From the machine learning approach, the formation energy of oxides MxOy emerges as the most crucial feature dominating the route of interface reactions, implying that the M–O bond strength governs the interface stability of the cation-doped LLZOM. The machine learning model then predicts 18 unexplored LLZOM systems, which are all validated in subsequent calculations. Our work offers practical insights for experimentalists into the selection of appropriate dopants in LLZO to stabilize Li metal anodes in solid-state batteries.

“Phonon-Liquid Electron-Crystal (PLEC)” materials are attractive thermoelectric systems due to their emergent liquid-like behavior, which potentially leads to ultralow lattice thermal conductivity and moderate thermoelectric performance at high temperature. In this paper, the “liquid-like” state's atomic structure of the quasi-2D PLEC AgCrSe2 is directly studied by in situ scanning transmission electron microscopy and ab initio molecular dynamics. It is revealed by experiments that the diffusing Ag atoms in the liquid-like state prefer to occupy lattice sites as in a disordered solid, a feature very distinct from that of real liquids, and theoretical calculations predict that the characteristic time for Ag+ diffusion is too slow to disrupt vibrations. A simple slow diffusion model is proposed to elucidate the “liquid-like” behavior, and the ultralow lattice thermal conductivity can be explained within the framework of disorder solids.

In this work, two TiNiV alloys with nominal compositions of Ti46Ni44V10 and Ti37Ni38V25 were prepared by casting. Thin wires were acquired by cold drawing. The microstructure, transformation characteristics and mechanical properties of the wires were investigated. The microstructure analysis showed that β-V phase was stretched into nanowires after drawing. The results suggested that the R → B19′ transformation increases with increasing annealing temperature. The tension test showed that after 400 °C annealing, the two alloys exhibited superior superelastic. Both of the alloys exhibit high transformation critical stress and large hysteresis. The Ti46Ni44V10 alloy exhibited critical transformation stress of about 575 MPa and reversible strain of about 7% in 8% superelastic cycle. The Ti37Ni38V25 alloy exhibits critical transformation stress of about 1100 MPa and reversible strain of about 6% when annealed at 400 °C. Ti37Ni38V25 alloy exhibited high absorbed energy of about 54 MJ/m3 in 8% superelastic cycle, which is about 3 times higher than that in the NiTi alloy.

In this paper, an optical pressure sensor based on pressure-induced birefringence in Lithium Niobate (LN) crystal is designed to achieve large sensing dynamic range. By using the photo-elastic effect of LN crystal, the optical phase change caused by the external pressure can be converted into the change of the output light intensity. Considerable sensor range can be obtained without special processing of the LN crystal, which makes it have high pressure tolerance. The sensing range of 24.85 MPa is demonstrated to be achievable on x-cut LN crystal with a length of 10 mm in the z-axis direction. The sensing sensitivity can reach 0.281 mW/MPa. By customizing the sensing range, it is expected to use the LN crystal based pressure sensor with the ease of fabrication to monitor high pressure scenarios, such as marine and large buildings monitoring.

To understand the effect of cold working of welding heat-affected zone on the driving force of the crack growth and crack growth rate of stress corrosion cracking (SCC) near the welding fusion line, the finite element simulation method was used to analyze the effect of cold working on the tensile stress of the crack tip at different locations near the fusion line. On this basis, the strain rate of the crack tip in the Ford-Andresen model is replaced by the creep rate of the crack tip, and the creep rate of the crack tip is used as driving force for the crack growth of SCC. The effect of the cold working level at the heat-affected zone on the driving force of the crack growth and crack growth rate of SCC are analyzed, and driving force of the crack growth and crack growth rate of SCC after one overload was compared.

The effect of plastic deformation of V nanowires on the transformation characteristics of two NiTiV alloys was investigated. A significant increase of B19′→B2 transformation temperatures in the deformed samples during the initial heating process was found. In the subsequent cooling process, the R→B19′ transformation temperatures were higher than the as-annealed samples. Upon second heating, the B19′→R transformation temperatures were higher than the as-annealed samples, but the change was much smaller than the R→B19′ transformation. All of these phenomena are closely related to the plastic deformation of V nanowires during deformation.

In situ Cu-Ni3Ti composites with near-eutectic compositions of Cu96Ni3Ti1 and Cu92Ni6Ti2 were prepared by casting. Microstructure analysis showed that multi-scale Ni3Ti particles are present in the...

An integrated optical pressure sensor based on a SiO2 arrayed waveguide grating (AWG) and a phase amplifying pressure block (PAPB) 3D-printed with stereolithography resin is described in this paper. Theoretical analysis of the AWG shows that its sensitivity can be improved by applying pressure on the PAPB instead of the whole chip. This scheme is shown to be feasible by mechanical simulation of a 1 mm-thick SiO2 chip. We use the standard planar lightwave circuit (PLC) process to fabricate a SiO2 AWG and 3D print the PAPB using stereolithography resin SOMOS Imagine 8000. Adding the PAPB module to the AWG chip improves the sensitivity of the sensor by 9 times, and the measuring range reaches 80 MPa. The resolution of the device reaches 0.0007% FS (full scale).

Integrated pressure sensor based on SiO2 arrayed waveguide grating (AWG) for large range and linear measurement is realized. By analyzing the shape change and photoelastic effect of the arrayed waveguides, the change trend of AWG’s central wavelength with pressure is calculated. AWG pressure sensor is fabricated by standard planar lightwave technology. The measured variation on central wavelength with pressure, 0.01853 nm/MPa, shows good linearity and agrees well with the theoretical calculation (0.01729 nm/MPa). The AWG sensor can withstand 40 MPa pressure and the resolution is 0.011% FS (Full-scale). The measurement results are not affected by the distortion and power attenuation of light source. Therefore, in addition to the temperature effect, the sensor is long-term calibration free.

The present study investigated the effects of morphology of V nanowires on superelasticity of Ti46Ni44V10 alloy. The microstructure analysis revealed that the diameter of V nanowires decreased and the continuity improved with an increase in cold drawn deformation. The upper plateau stress decreased with the increase in annealing temperature and increased with the increase in cold working. Furthermore, the superelastic strain decreased with the increase in annealing temperature. However, it was independent of cold working. The stress hysteresis increased with the increase in area reduction, and the samples annealed at 400 °C exhibited a larger hysteresis than those annealed at 350 °C when the area reduction was more than 40%. Thus, we found that, the effects on superelasticity of Ti46Ni44V10 alloy were closely related to the morphology of V nanowires and the NiTi phase.

In this work, the V40Ni31Ti29 alloy wires were acquired by casting, forging and drawing process. The transformation characteristics of the V40Ni31Ti29 alloy wires with dual-scale bcc-V were studied. The results suggest that B19′→B2 transformation peak temperatures are higher than 100 °C and decreases with the increasing annealing temperature. The transformation temperature range is about 80 °C, which is much higher than the results of NiTiV alloys with lower V element content. We propose that this result is closely related to the differrent plastic deforamtion of V nanowires and micro fibers. The B2↔R transformation temperatures increased after tension loading-unloading cycle, which is ascribed to the plastic deformation of V fibers.

Effect of cold work and heat treatment on martensitic transformation of Ni38Ti37V25 alloy was investigated by tensile test and DSC analysis. The microstructure analysis revealed that the diameter of V nanowires reduced after the cold-drawn process. The critical transformation stress and reversible transformation strain increased with the increasing area reduction. During the first heating process, the B19’→B2 transformation of the samples annealed at 400 °C decreased with the increasing area reduction. Upon cooling and the following heating process, the B2→R transformation temperature differences were much lower than that of R→B19’ transformation. All of these phenomena are closely related to the diameter of V nanowires and the plastic deformation during tensile test.

Chemical bond hierarchy (CBH) depicts a unique structural type of solids, in which fractions of the materials are loosely bonded in a relatively rigid framework. The weak bonding in materials with CBH induces special atomic vibrational motions and has a significant influence on the thermoelectric transport properties. The architecture of compounds with CBH was first proposed by Slack in his 'phonon glass electron crystal' paradigm and has led to the discovery of numerous new thermoelectric compounds over the years. This review covers various types of thermoelectric materials with different levels of CBH, focusing on their lattice thermal conductivities (κ Ls). Caged compounds, with foreign impurities in the cages as the rattlers, are the first type of compounds stimulating the study of CBH. The fillers in both the clathrates and the filled skutterudites greatly reduce the κ L accompanied by abnormal temperature dependence. As reviewed herein, the reduced κ L is attributed to different mechanistic sources, i.e., the resonant scattering or the enhanced anharmonic phonon scatterings. Both may contribute to the κ L reductions. In recent years, more materials with different types of CBH have been discovered, some containing complex atomic clusters as the rattlers, and others having flowing atoms that cause multiple equilibrium sites and even liquid-like behaviors. All CBHs strongly interfere with the heat transport of the corresponding materials. Future perspectives and possible research directions for thermal transport in thermoelectric materials with CBH have also been summarized herein.

A dmit2- salt: bis(tetraethylammonium)bis(1,3-dithiole-2-thione-4,5-dithiolato)cadium (CADMIT) was synthesized. The Optical Kerr Effect (OKE) signal of its acetonitrile solution was measured by femtosecond optical Kerr gate technique. Using CS2 OKE signal as reference signal measured under identical conditions, the third-order optical nonlinear susceptibility, c(3), of the sample solution was obtained to be about 2.98 x 10-14 esu at the concentration of 1.57 x 10-3 M. The second-order hyperpolarizability of its molecular was estimated to be as large as 1.23 x 10-32 esu. Its response time was about 195 fs, which is believed to be the contribution from the delocalized electrons.

A novel chalcone derivative, (2E)-1-(2,4-di- chloro-5-fluorophenyl)-3-[4-dimethylamino)phenyl]prop-2-en-1-one, abbreviated as NNDC, was prepared and characterized by elemental analyses, infrared (IR) and proton nuclear magnetic resonance (1H NMR) spectrum, and thermal analyses. The NNDC-doped poly(methyl methacrylate) (PMMA) thin films with five different doping concentrations by weight were prepared by using a spin-coating method. Their linear optical properties were investigated by using a prism coupling measuring system. The third-order nonlinear optical properties of NNDC in 1,2-dichloroethane (NNDC/1,2-dichloroethane) solution and NNDC-doped PMMA (NNDC/PMMA) films were investigated by using the laser Z-scan technique with 20 ps pulses at 532 nm. A self-focusing effect was observed from the Z-scan curves for solution and thin films and the nonlinear refractive index of the film increases with the increase of the doping concentration. In addition, nonlinear absorption was negligible for all samples. The magnitude of third-order nonlinear refraction index n 2 and the third-order nonlinear susceptibility χ (3) for thin films were 10−15 m2/W and 10−9 esu, respectively, which are about three orders larger than that of NNDC/1,2-dichloroethane solution. Some necessary analyses were presented. The results show that this material is a promising candidate for application in the nonlinear optical devices at 532 nm.

An organometallic complex, bis(tetra-n-propylammonium)bis(2-thioxo-1,3-dithiole-4,5-dithiolato)cuprate(II), [(C3H7)4N]2[Cu(dmit)2] (dmit2−=4,5-dithiolate-1,3-dithiole-2-thione), abbreviated as PrCu, was synthesized. The films of PrCu were prepared using spin coating method. The third-order nonlinear optical properties of PrCu in acetone solution and PMMA films were investigated by Z-scan technique at 1064 nm with laser duration of 20 ps. The Z-scan spectra reveal that the composite films exhibit large negative nonlinear refractive indices of the order of 10−15 m2/W, which are three orders larger than that in acetone solution. The nonlinear absorption coefficients were calculated to be 9.416×10−10 m/W. For the composite films, the figure of merit, W and T, meet the requirement of all-optical switching devices. The experimental results show that the PrCu-doped PMMA films have potential applications for nonlinear optical devices.

For the demand of energy conservation and security improvement, high-strength steel (HSS) is increasingly being used to produce safety related automotive components. However, cross-section distortion occurs easily in bending of HSS tube with rectangular section (RS), affecting the forming precision. HSS BR1500HS tube by rotary draw bending is taken as the study object and a description method of cross-section distortion is proposed in this paper. The influence on cross-section precision of geometric parameters including cross-section position, thickness of tube, bend radius etc. are studied by experiment. Besides, simulation of the rotary draw bending of HSS tube with rectangular section by ABAQUS are carried out and compared to the experiment. The results by simulation agree well with the experiment and show that the cross-section is approximately trapezoidal after distortion; the maximum of distortion exists at 45 ~ 60° of the bending direction; and the absolute and relative distortion values increase with the decreasing of tube thickness or bending radius. Therefore, the results can provide a reference for the design of geometric parameters of HSS tube with rectangular section in rotary draw bending.

Bis(tetrabutylammonium)- Hg(dmit) 2 was synthesized and its sample solution's optical Kerr Effect (OKE) signal was measured by the femtosecond optical Kerr gate technique. With the concentration of 9.27 × 10-4 M, the sample solution's third-order optical susceptibility was obtained to be 2.53 × 10-14 esu by using the CS2 OKE signal as reference signal measured under identical conditions. The second-order hyperpolarizability for the bis(tetrabutylammonium)- Hg(dmit) 2 molecular was estimated to be 1.7 × 10-32 esu. Its response time was about 226 fs, which is believed to be the contribution from the delocalized electrons.

Composite thin films of PbTiO3 nano-crystals and high transparency polymer polyetherketone (PEK-c) for application of non-linear optical devices were prepared by spin coating. The size of PbTiO3 nano-crystals was estimated to be 30–40 nm using a transmission electron microscope. The refractive index and the mode propagation losses at 633 nm were measured using the prism coupling technique and improved photographic technique respectively. They were found to be 1.6545 and 2.00 dB cm−1 (fundamental mode), respectively. Moreover, it is observed that this loss is increased at higher mode indices.

A dmit2− salt: bis(tetrabutylammonium)bis(1,3-dithiole-2-thione-4,5-dithiolato) cadium (BCDT) was synthesized. The Optical Kerr Effect (OKE) signal of its acetone solution was measured by femtosecond optical Kerr gate technique. Using CS2 OKE signal as reference signal measured under identical conditions, the third-order optical nonlinear susceptibility, χ(3), of the sample solution was obtained to be about 1.08 × 10−13 esu at the concentration of 3.4 × 10−4 M. The second-order hyperpolarizability for BCDT molecular was estimated to be as large as 1.9 × 10−31 esu. Its response time was about 239 fs, which is believed to be the contribution from the delocalized electrons.

A dmit2− salt: bis(tetraethylammonium)bis(1,3-dithiole-2-thione-4,5-dithiolato) mercury (EMDT) was synthesized. The optical Kerr effect (OKE) signal of its acetone solution was measured by the femtosecond optical Kerr gate technique. Using the CS2 OKE signal as a reference signal measured under identical conditions, the third-order optical nonlinear susceptibility, χ(3), of the sample solution was obtained as about 6.193 × 10−14 esu at the concentration of 1.39 × 10−4 M. The second hyperpolarizability for molecular EMDT was estimated to be as large as 2.73 × 10−31 esu. Its response time was about 184 fs, which is believed to be the contribution from the delocalized electrons.

Bismuth titanate, Bi4Ti3O12 (BTO), is a typical ferroelectric material with useful properties for optical memory, piezoelectric and electro-optic devices. Its nano-crystals were compounded by the chemical solution decomposition technique. Its structure and size were analyzed by X-ray diffraction and transmissive electron microscopy. The composite thin film of BTO nano-crystals and high transparency polymethylmethacrylate (PMMA) polymer was prepared by spin coating. The transmitted spectrum of BTO/PMMA composite thin film in 300– 1500 nm was measured. The film thickness d and the optical constants of the film, such as the refractive index n, the absorption coefficient α, and the extinction coefficient κ were obtained using the data from the transmitted spectrum.

A (100)-oriented Fe-doped NBT Na0.5Bi0.5TiO3 (NBTFe) thin film was fabricated on LaNiO3(100)/Si substrate using a chemical solution deposition process, in which the solution precursor was modified by polyethylene glycol with a molecular weight of 600 (PEG600). The effects of PEG600 for crystalline structure, morphology, and electrical properties of NBTFe thin film were characterized. It is observed that with the PEG600 additive, phase-pure perovskite can be obtained for NBTFe thin film at a relatively lower annealing temperature of 500 °C. Moreover, in NBTFe thin film with PEG600 modification, enhanced ferroelectricity is achieved with a larger remanent polarization (Pr) of 21.9 μC/cm2, and the values of the dielectric constant and dissipation loss at 100 kHz are estimated to be 411 and 0.153, respectively.

A thin-film bilayer structure consisting of polycrystalline Pb 0.85 Sm 0.1 TiO 3 and preferentially (111)-oriented Bi 2 Ti 2 O 7 were prepared using the chemical solution deposition technique. Thin films were deposited by spin-coating. The structural properties of the films were examined by X-ray diffraction. The surface morphology and quality were studied by using an atomic force microscope. The films exhibit a good insulating property and resistance to breakdown. The clockwise hysteresis curve is referred to as polarization type switching, and the memory window is about 3.5 V. The accumulation capacitance and dielectric loss decrease with the increased annealing temperature. The ( Pb, Sm ) TiO 3/ Bi 2 Ti 2 O 7 films in the "on" and "off" states are relatively stable.

Bismuth titanate, Bi4Ti3O12 (BTO), is a typical ferroelectric material with useful properties for optical memory, piezoelectric and electro-optic devices. Its nano-crystals were compounded by the chemical solution decomposition technique. The structure and size of BTO were analyzed by X-ray diffraction and transmissive electron microscopy. Two sorts of composite films BTO/polymethylmethacrylate with different weight ratio of BTO were prepared by spin-coating method at certain conditions. In this article, the scattering loss in thin films was obtained using an imaging technique.

Three 1,3-dithiole-2-thioxo-4,5-dithiolato compounds, ethyltriphenylphosphonium bis(2-thioxo-1.3-dithiole-4,5-dithiolato)aurate(III) (TPEPADT), benzyltriethylamine bis(2-thioxo-1.3-dithiole-4,5-dithiolato)aurate(III) (BTEAADT) and benzyltriethylamine bis(2-thioxo-1.3-dithiole-4,5-dithiolato)nickel(III) (BTEANDT), were synthesized and the BTEAADT-doped PMMA thin film (BD film) and TPEPADT-doped PMMA thin film (TD film) with mass fraction of 1% were prepared by spin-coating method. The third-order nonlinear optical properties of thin films and three compounds in acetonitrile solutions were investigated by using the laser [Formula: see text]-scan technique with 20 ps pulses at 1064 nm. The [Formula: see text]-scan spectra revealed that TPEPADT and BTEAADT exhibited self-defocusing effect and negligible nonlinear absorption, but BTEANDT exhibited self-focusing effect and stronger saturable absorption. The reason for this difference was analyzed. The magnitudes of third-order nonlinear refractive indices and third-order nonlinear susceptibility were [Formula: see text], 10[Formula: see text] esu for the solution samples and [Formula: see text], [Formula: see text] esu for thin films. All these results suggest that these materials are promising candidates for application in the nonlinear optical area at infrared band.

A three-dimensional comprehensively coupled model has been developed to describe the transport phenomena, including fluid flow, heat transfer, solidification, and solute redistribution in the continuous casting process. The continuous casting process is considered as a solidification process in a multicomponent solid-liquid phase system. The porous media theory is used to model the blockage of fluid flow by columnar dendrites in the mushy zone. The relation between flow pattern and the shape of the solid shell is demonstrated. Double diffusive convection caused by thermal and concentration gradients is considered. The change in the liquidus temperature with liquid concentration is also considered. The formation mechanism of macrosegregation is investigated. Calculated solid shell thickness and temperature distribution in liquid core are compared with the measured quantities for validating the model.

A novel dmit2- complex: [C7H7 (C2H5)3N] [Au (dmit)2 ] (BTEAADT) was synthesized. The thin film of BTEAADT doped into poly (methyl methacrylate) (PMMA) was prepared using spin-coating method. Its third- order nonlinear optical (NLO) properties were investigated using Z-scan technique at the wavelength of 1064 nm with laser pulse duration of 20 ps. The linear optical properties of the thin film were also studied. A self-defocusing effect was observed from the Z-scan curve and no nonlinear absorption was observed in the experimental conditions. The nonlinear refractive index is calculated to be -3.978×10-15m2/w.The figures of merit were evaluated for their value of potential application on all-optical switching (AOS) devices, etc.

A dmit2- salt: [(C 4 H 9 ) 4 N]Au(dmit) 2 was synthesized. Its third-order nonlinear optical properties of its acetone solution were investigated by Z-scan technique using a pulsed laser with 28 ps duration and 10 Hz repetition at 532 nm. The third-order nonlinear refractive index n 2 and nonlinear absorption coefficient β of the sample solution were obtained to be about 4.997×10−12 esu and 1.818 cm/GW at the concentration of 2×10−3 M. The second-order hyperpolarizability for its molecular was estimated to be as large as 2.74×10−31 esu, suggesting [(C 4 H 9 ) 4 N]Au(dmit) 2 is a promising material for all-optical switching.

An organic material, 4,5-bis(benzoylthio)-1,3-dithiole-2-thione (BBDT), was synthesized. The thin film of BBDT doped into poly(methyl methacrylate) (PMMA) was prepared using spin-coating method. Its linear optical properties were characterized with prism coupler (SPA-4000, Korea). The third-order nonlinear optical (NLO) properties were investigated using Z-scan technique with pulses of picoseconds at 532 nm. The Z-scan spectra reveal a strong nonlinear absorption (reverse saturable absorption) and a positive nonlinear refraction. The nonlinear absorption coefficient is calculated to be 1.302×10−9m/W. The nonlinear refractive index is 2.243×10−9esu. The results show that the film exhibits a great nonlinear optical response.

Bismuth titanate, Bi4Ti3O12 (BTO), is a typical ferroelectric material with useful properties for optical memory, piezoelectric and electro-optic devices. Its nano-crystals were compounded by the chemical solution decomposition (CSD) technique. The structure and size of BTO were analyzed by X-ray diffraction (XRD) and transmissive electron microscopy (TEM). Three sorts of composite films BTO/PEK-c with different BTO concentration were prepared by spin-coating method at certain conditions. In this article, the scattering losses in thin films were obtained using the photographic technique. The losses in the films with different BTO weight ratios were compared and analyzed.