Preparation and Characterization of Layered Compound Zirconium Bis(monohydrogenphosphate) Intercalated with Rare Earth Complex

Layered compound zirconium bis(monohydrogenphosphate)(alpha-ZrP) intercalated with rare earth complex Eu(DBM)(3)phen was prepared. The pre-intercalation of p-methoxyaniline into alpha-ZrP makes the interlayer separation large enough to exchange PMA with europium complex, thus, the luminescent assembly was prepared. This was confirmed by X-ray diffraction, UV-visible spectra and elemental analysis. The fluorescence spectra and lifetime of the assembly were also presented.

Electronic structure and mechanical properties of layered compound YB_2C_2:A promising precursor for making two dimensional(2D) B_2C_2 nets

Layered compounds play pivotal roles as precursors for producing 2D materials through mechanical exfoliation(micro-mechanical cleavage) or chemical approaches. Therefore, searching for layered compounds with sharp anisotropic chemical bonding and properties becomes emergent. In this work, the stability, electronic structure, elastic properties, and lattice dynamics of YBCwere investigated. Strong anisotropy in elastic properties is revealed, i.e., high Young’s modulus in a-b plane but low Young’s modulus in c direction. The maximum to minimum Young’s modulus ratio is 2.41 and 2.45 for YBCwith P42/mmc and P4/mbm symmetry, respectively. The most likely systems for shear sliding or microdelaminating are(001)[100] and(001)[010]. The anisotropic elastic properties are underpinned by the anisotropic chemical bonding, i.e., strong bonding within the BCnets and weak bonding between Y atom layers and BCnets. YBCis electrically conductive and the contributions to the electrical conductivity are from delocalized Y 4deas well as Bpandpzelectrons. The layered crystal structure, sharp anisotropic mechanical properties, and metallic conductivity endorse YBCpromising as a precursor for new 2D BCnets.

Raman Spectroscopy of Layered Compound YbB_(2)C_(2)

REB_(2)C_(2)(RE=Y and lanthanides)compounds have gained attention for their unique layered crystal structure.However,there have been few reports about Raman spectroscopy of REB_(2)C_(2) compounds up to now.Here,the Raman spectrum of YbB_(2)C_(2) is obtained by a micro-Raman spectroscope and the first-principles calculations.Raman active vibrational modes of YbB_(2)C_(2) are confirmed as A_(1g)(627 and 1311 cm^(-1)),B_(1g)(944 and 1172 cm^(-1)),B_(2g)(330 and 885 cm^(-1))and E_(g)(357 and 530 cm^(-1)).Atomic displacements of these modes are different,they can be divided into two groups:A_(1g)’,B_(1g) and B_(2g) correspond to ring breathing(δ_(in),in the plane)of B_(2)C_(2) layer;E_(g) is due to ring deformation(δ_(oop),out of the plane)of B_(2)C_(2) layer.These results are helpful to understand the individual structure of REB_(2)C_(2).

Quantum Size Effect of the Magnetism of an Electron in a Metal Layer of the Layered Compounds M/I/M/I…

The energies and the magnetization of an electron in a piece of metal in the structure of Metal/Insulator/Metal/Insulator… (M/I/M/I…), in a magnetic field, at high temperature, and in range of quantum size thickness of the piece of metal layer have been obtained. The results show that when the thickness of the metal layer becomes smaller, the orbital magnetism of the charged particles which collide with the wall of the metal layer is to vary from diamagnetism to paramagnetism. The smaller the thickness of the metal layer becomes, the more particles will collide with the boundary of the metal layer, and then the paramagnetism becomes stronger. Finally, when the thickness of the metal layer becomes very small (<100 nm), all of the orbital diamagnetism will reverse to paramagnetism, and then the paramagnetization will be almost a maximum constant.

Synthesis and antibacterial activity of new layered perovskite compounds,Ag_xNa_(2-x)La_2Ti_3O_(10)

Three kinds of new layered perovskite compounds with Ruddlesden-Popper （R-P） phase, AgrNa2-xLa2Ti3O10 （x = 0.2, 0.3 and 0.5）, were synthesized by an ion-exchange reaction of Na2La2Ti3O10 with AgNO3 solution. The structures of the compounds were characterized by EDX and XRD, and their antibacterial activity and light-resistance property were evaluated. The results indicated that the molecular formula of AgxNa2-xLa2Ti3O10 （x = 0.2, 0.3 and 0.5） was confirmed, and that the crystalline structure of Na2La2Ti3O10 was not obviously affected by exchange of silver ion. The minimum inhibitory concentrations （MICs） of Ag0.3Na1.7La2Ti3O10 against Escherichia coli （E. coli）, Staphylococcus aureus （S. aureus） were 180 μg/mL and 240 μg/mL, respectively, while its discoloration was not observed after 24 h light ageing test.

Preparation,Characterization and Application of ZnAlLa-Hydrotalcite-Like Compounds

The preparation of ZnAlLa-hydrotalcite-like compounds [ZnAlLa-HTLcs] wasstudied. ZnAlLa-HTLcs were synthesized by a method of variable pH with the raw materials ofZn(NO_3)_2, Al(NO_3)_3, La(NO_3)_3, and NaOH. The eS'ccts of some factors (i.e. pH values, the moleratio of Al^(3+) to La^(3+), temperature and the period of hydrothermal treatment) on thepreparation of HTLcs were discussed systematically. XRD, TG-DTA, FT-IR spectroscopy, and ICP wereperformed to characterize ZnAlLa-HTLcs samples, and the thermal stability of HTLcs was alsodiscussed. It was shown that unique ZnAlLa-HTLcs with high crystallinity can be prepared, under theconditions of pH = 5.5-6.5, n(Zn^(2+))/n(Al^(3+) + La^(3+))=2 and the atomic ratio of La^(3+) toAl^(3+) ranging from 0.07 to 2, hydrothermal treatment at 120 ℃ for 5 h. When the calcination ofthe HTLcs is performed at temperatures above 200 ℃, ZnO phase is detected with Al_2O_3 and La_2O_3spreading on its top. The complex metal oxides derived from ZnAlLa-HTLcs at 500 ℃ have highercatalytic activity and selectivity than those from ZnAl-HTLcs for the esterification of acetic acidwith n-butanol under the same reaction conditions.

INFRARED SPECTROSCOPIC STUDY OF STRUCTURE TRANSITION IN THE PEROVSKITE-TYPE LAYER COMPOUND: (n-C_9H_(19_NH_3)_2CuCl_4

Infrared spectra of (n-C_9H_(19)NH_3)_2CuCl_4 in three solid phases were investigated. It was found that the phase transition at T_(cl)(25℃) arises from the change of the interaction and packing structure of the chain. The phase transition at T_(c2)(34℃)is related to the change of a partial conformational order-disorder. The GTC or GTG' and small concentration of TG structure near CH_3 group exist in phase Ⅲ (above 38℃).

Low contact resistivity between Ni/Au and p-GaN through thin heavily Mg-doped p-GaN and p-InGaN compound contact layer

Thin heavily Mg-doped InGaN and GaN compound contact layer is used to form Ni/Au Ohmic contact to p-GaN. The growth conditions of the compound contact layer and its effect on the performance of Ni/Au Ohmic contact to p-GaN are investigated. It is confirmed that the specific contact resistivity can be lowered nearly two orders by optimizing the growth conditions of compound contact layer. When the flow rate ratio between Mg and Ga gas sources of p＋＋-InGaN layer is 10.6% and the thickness of p＋＋-InGaN layer is 3 nm, the lowest specific contact resistivity of 3.98× 10-5 Ω cm2 is achieved. In addition, the experimental results indicate that the specific contact resistivity can be further lowered to 1.07 × 10-7Ω.cm2 by optimizing the alloying annealing temperature to 520 ℃.

Effect of the Compound Layer of Plasma Nitriding on Thermal Fatigue Behavior of 4Cr5MoSiV1 Die Steel

With the Uddeholm self restricted method, the effect of compound layer of plasma nitriding on thermal fatigue behavior of 4Cr5MoSiV1 steel was studied by the way of adding Ar during plasma nitriding to remove the compound layer. The results show that the compound layer of plasma nitriding can delay the nucleation of heat cracks and hold back the propagation of heat cracks from surface to substrate because of its high hardness and strength. On the other land, the heat checking expands faster with the compound layer on the surface than that without it. After 3000 cycles of thermal fatigue test, both heat cracks with the compound layer are wider than the another without compound layer and the number of heat cracks of the former is more from the view of cross section.

Compound buried layer SOI high voltage device with a step buried oxide

A silicon-on-insulator （SOI） high performance lateral double-diffusion metal oxide semiconductor （LDMOS） on a compound buried layer （CBL） with a step buried oxide （SBO CBL SOI） is proposed. The step buried oxide locates holes in the top interface of the upper buried oxide （UBO） layer. Furthermore, holes with high density are collected in the interface between the polysilicon layer and the lower buried oxide （LBO） layer. Consequently, the electric fields in both the thin LBO and the thick UBO are enhanced by these holes, leading to an improved breakdown voltage. The breakdown voltage of the SBO CBL SOI LDMOS increases to 847 V from the 477 V of a conventional SOI with the same thicknesses of SOI layer and the buried oxide layer. Moreover, SBO CBL SOI can also reduce the self-heating effect.

Thickness of compound layer in steel-aluminum solid to liquid bonding

The bonding of solid steel plate to liquid aluminum was studied using rapidsolidification. The surface of solid steel plate was defatted, descaled, immersed (in K_2ZrF_6 fluxaqueous solution) and stoved. In order to determine the thickness of Fe-Al compound layer at theinterface of steel-aluminum solid to liquid bonding under rapid solidification, the interface ofbonding plate was investigated by SEM (Scanning Electron Microscope) experiment. The relationshipbetween bonding parameters (such as preheat temperature of steel plate, temperature of aluminumliquid and bonding time) and thickness of Fe-Al compound layer at the interface was established byartificial neural networks (ANN) perfectly. The maximum of relative error between the output and thedesired output of the ANN is only 5.4%. From the bonding parameters for the largest interfacialshear strength of bonding plate (226℃ for preheat temperature of steel plate, 723℃ for temperatureof aluminum liquid and 15.8 s for bonding time), the reasonable thickness of Fe-Al compound layer10.8 μm was got.

Synthesis of Layered Hydroxide Zinc m-Aminobenzoate Compounds and Their Exfoliation Reactions

Two types of layered hydroxide zinc m-aminobenzoate compounds with structures of layered basic metal salt （LBMS） were prepared by the reaction of zinc hydroxide with m-aminobenzoic acid solution in the temperature range of 40----120℃. The formation reactions, structures, chemical compositions, and exfoliation reactions of the layered compounds in alcohol solvents were investigated by XRD, TG-DTA, SEM, and TEM. One layered phase with a basal spacing of 1.08 nm has a a-Ni（OH）2-1ike structure, and its chemical formula can be written as Zn（OH）0.67（m-NH2C6HaCOO）l.33. This phase has strip-like particle morphology and cannot be exfoliated into its nanosheets in alcohol solvents. The other layered phase with a basal spacing of 2.66 nm has a zinc hydrox- ide-nitrate-like structure, and can be exfoliated in alcohol solvents.

Synthesis and Crystal Structure of Salicylyl-4-phenyl Thiosemicarbazide Lead with a Two-dimensional Network

A two-dimensional lead complex, [Pb（C14N3O2H12S）（NO3）]n·nH2O, was prepared by the reaction of salicylyl-4-phenyl thiosemicarbazide and lead nitrate. The compound （C14H13N4O6PbS, Mr = 572.53） crystallizes in the monoclinic space group P21/c with a = 11.2984（2）, b = 15.6628（7）, c = 11.1118（2）A,β= 113.564（2）°, V = 1802.43（10）A3, Dc= 2.110 g/cm3, Z = 4,μt（MoKα） = 9.515 mm-1, F（000） = 1084, the final R = 0.0394 and wR = 0.0701 for 2552 observed reflections with I 〉 2σ（I）. The Pb（Ⅱ） ion displays a distorted octahedron in which the hypothesized stereochemically active lone pair occupies the apex. The compound exhibits a two-dimensional network structure formed by the zigzag one-dimensional chains joined by two μ-O of two nitrate groups in overlapping. A large ring exists in the two-dimensional layers. The TGA of the title compound has been studied.

Influence of Processing Parameters on the Mechanical Properties of a Plasma Radical Nitrided SCM440 Steel

Plasma radical nitriding was performed to harden the surface of SCM440 steel for 1-10 h at temperature range of 450-550℃. This process involved the use of NH3 gas instead of N2 gas employed for the well-established plasma nitriding method. No compound layer was formed during this process except the experiment carried out at 500℃ for 10 h. The main phase produced in the diffusion zone was identified to be γ＇-Fe4（N, C）. A diffusion depth increased with increasing treatment temperature and time （up to about 250 μm）. The surface hardness of radical nitrided layer was about two times higher than that of the untreated surface. The tensile test was carried out to estimate the mechanical properties of surface-hardened SCM440 steel prepared at various plasma radical nitriding treatment time and temperature. The influence of radical nitriding treatment on the tensile strength of the specimen was found to be insignificant. The highest value of the ultimate tensile strength was obtained in the experiment carried out at 500℃ for 1 h. However, the elongation was greatly affected by the radical nitriding processing parameters. The maximum value of elongation, which is equal to about 18.1%, was also obtained under the condition of 500℃ for 1 h.

STUDY ON FORMATION MECHANISM OF ADHERING LAYER FORMED ON TOOL FACE

The appearance of adhenng layer formed on tool face, its composition and distributionare analysed when Ca-S free-cutting stainless steel is machined. Cutting temperature field and itsrelation with formation of the layer is also studied. The result shows that, the layer can be formed under proper temperature condition, the stable cutting temperature field keeps the stable layer, itsthickness and composition distribution along rake face depend on the corresponding cutting tem-perature field. The theoretical model of the layer formation is set up.

Ultrathin 3 V Spinel Clothed Layered Lithium-Rich Oxides as Heterostructured Cathode for High-Energy and High-Power Li-ion Batteries

In an attempt to overcome the drawbacks of high-capacity layered lithium-rich cathodes xLi2MnO3·(1–x)LiMO2(0<x<1,M=Mn,Ni,and Co),the spinel clothed layered heterostructured materials,x’Li4Mn5O12·(1–x’)Li[Li0.2Mn0.55Ni0.15Co0.1]O2(x’=0.01,0.03,0.05)have been proposed and synthesized as high-performance cathode materials for high-energy and high-power Li-ion batteries.Based on the characterizations of X-ray diffraction(XRD),transmission electron microscopy(TEM),Raman scattering spectroscopy,it is indicated that ultrathin 3 V spinel Li4Mn5O12 has been successfully clothed on the layered lithium-rich cathode.Electrochemical tests demonstrate the sample 0.01Li4Mn5O12·0.99 Li[Li0.2Mn0.55Ni0.15Co0.1]O2 with an ultrathin clothing layer of spinel phase,exhibits the highest reversible capacity of 289.4 mAh g^(-1) and maintains 259.8 mAh g^(-1) after 80 cycles at 0.1 C rate.Meanwhile,it delivers outstanding rate discharge capacities of 229.4 mAh g^(-1) at 1 C,216.8 mAh g^(-1) at 2 C and 184.4 mAh g^(-1) at 5 C as well as alleviated voltage fade.It is believed the ultrathin clothing spinel layer plays a vital role in the modification of the materials kinetics,and structural and electrochemical stability of the heterostructured cathode.

Thixotropy of Aqueous Suspensions Containing Mg-AI Hydrotalcite-like Compound and Low-substituted Cationic Starch： Comparison between Oscillatory Shear and Thixotropic Loop Measurements

The rheological properties of aqueous suspensions consisting of positively charged aluminum magnesium hydrotalcite-like compound （HTlc） and low-substituted cationic starch （LCS） were investigated. Special emphasis was placed on the thixotropic phenomenon. Thixotropic behavior was investigated by two thixotropic methods： thixotropic loop and oscillatory shear measurements. LCS molecules could be adsorbed onto HTlc particles due to the hydrogen bonding between ether groups or hydroxyl groups of LCS and hydroxyl groups of HTlc. The elastic dynamic response of the HTlc/LCS suspension increased with increasing mass ratio （R） of HTlc and a three-dimensional network structure could be formed in the suspension with higher R value. The thixotropic type of the HTlc/LCS suspension transformed from negative to positive and then to complex thixotropy when R changed from 0 to 0.5. By comparing between the thixotropic results obtained by thixotropic loop and oscillatory shear measurements, it was validated that the thixotropic loop for the suspension showing complex thixotropy had a crossover point.

A universal method for rapid and large‐scale growth of layered crystals

Layered van der Waals(vdW)materials,consisting of atomically thin layers,are of paramount importance in physics,chemistry,and materials science owing to their unique properties and various promising applications.However,their fast and large‐scale growth via a general approach is still a big challenge,severely limiting their practical implementations.Here,we report a universal method for rapid(~60 min)and large‐scale(gram scale)growth of phase‐pure,high‐crystalline layered vdW materials from their elementary powders via microwave plasma heating in sealed ampoules.This method can be used for growth of 30 compounds with different components(binary,ternary,and quaternary)and properties.The ferroelectric and transport properties of mechanically exfoliated flakes validate the high crystal quality of the grown materials.Our study provides a general strategy for the fast and large‐scale growth of layered vdW materials with appealing physiochemical properties,which could be used for various promising applications.

New materials and designs for 2D-based infrared photodetectors

Infrared photodetectors have attracted much attention considering their wide civil and military applications.Two-dimensional(2D)materials offer new opportunities for the development of costless,high-level integration and high-performance infrared photodetectors.With the advent of a broad investigation of infrared photodetectors based on graphene and transition metal chalcogenides(TMDs)exhibiting unique properties in recent decades,research on the better performance of 2D-based infrared photodetectors has been extended to a larger scale,including explorations of new materials and artificial structure designs.In this review,after a brief background introduction,some major working mechanisms,including the photovoltaic effect,photoconductive effect,photogating effect,photothermoelectric effect and bolometric effect,are briefly offered.Then,the discussion mainly focuses on the recent progress of three categories of 2D materials beyond graphene and TMDs.Noble transition metal dichalcogenides,black phosphorus and arsenic black phosphorous and 2D ternary compounds are great examples of explorations of mid-wavelength or even long-wavelength 2D infrared photodetectors.Then,four types of rational structure designs,including type-II band alignments,photogating-enhanced designs,surface plasmon designs and ferroelectric-enhanced designs,are discussed to further enhance the performance via diverse mechanisms,which involve the narrower-bandgap-induced interlayer exciton transition,gate modulation by trapped carriers,surface plasmon polaritons and ferroelectric polarization in sequence.Furthermore,applications including imaging,flexible devices and on-chip integration for 2D-based infrared photodetectors are introduced.Finally,a summary of the state-of-the-art research status and personal discussion on the challenges are delivered.

Studies on Mechanochemical Method to Synthesize LDH Nanoparticles

Magnesium-ferrum layered double hydroxide （Mg-Fe-LDH） and zinic-aluminum layered double hydroxide （Zn-A1-LDH） compounds were prepared through a mechanochemical method. The influence of molar ratio of M2＋ to M3＋ （R value） on the property ofLDH nanoparticles has been studied and the results showed that R=3 ： 1 is the optimum value for the both samples. Besides pure water, the mixture of water and ethanol with the volume ratio of 3 ; 1 is also used to wash the precipitates and used as suspending agent during the peptization process and our results showed that the addition of ethanol can improve the monodispersity of LDH nanoparticles greatly.