Synthesis and Characterization of Vanadium Molybdenum Oxynitrides Nanoparticles in the Channels of MCM-41

Vanadium molybdenum oxynitrides nanoparticles were synthesized successfully in the channels of MCM-41 after surface modification,vacumm co-impregnation and nitridation technology.The products were investigated by nitrogen sorption measurement,X-ray powder diffraction（XRD）,high-resolution transmission electron microscopy（HRTEM）,energy dispersive analysis of X-rays（EDAX）and CNH element analysis.The investigation resnlts show that superfine nanoparticles of vanadium molybderum oxynitrides exist in the channels of MCM-41.

NH_(4)Cl-assisted synthesis of TaON nanoparticle applied to photocatalytic hydrogen and oxygen evolution from water

Oxynitride semiconductors are promising photocatalyst materials for visible light-driven water splitting,while the synthesis of well crystalized oxynitride still remains challenge.In present work,narrow-bandgap TaON nanoparticles are synthesized via heating a vacuum-sealed mixture of KTaO_(3),Ta and NH_(4)Cl.This method possesses multiple advantages in terms of lower calcination parameter,higher N conversion efficiency and superior photocatalytic activity in comparison with the traditional thermal ammonolysis using NH_(3) gas as a nitrogen source.Through the analysis of intermediates produced upon the elevation of heating temperature,a gas-solid-phase reaction between TaCl_(5) and Ta_(2)O_(5) is demonstrated as the final step,which is conducive to decreasing thermal energy barrier and accelerating nitridation process.Precise control of preparation conditions,including calcination temperature and duration,allows for the regulation of surface O/N ratio of TaON particles to unity,resulting in optimized photocat-alytic activity.Photoelectrochemical assessment and intensity modulated photocurrent spectroscopy provide convincing evidence for improved charge transfer effciency of photoexcited holes at TaON surface.A Z-scheme overall water splitting is accomplished by employing the TaON as an effective oxygen evolution photocatalyst,SrTiO_(3):Rh as a hydrogen evolution photocatalyst,and reduced graphene oxide(rGO)as a solid-state electron mediator.This work presents a promising strategy for the synthesis of high-quality oxynitride materials in application to photocatalytic water splitting.

Enhanced polysulfide redox kinetics by niobium oxynitrides via insitu adsorptive and catalytic effect in wide temperature range

The development of Li-S batteries(LSBs)is hindered by the low utilization of S species and sluggish redox reaction kinetics.Polar metal oxides always possess high adsorption to polar S species,while conductive metal nitrides show fast electron transport and ensure fast redox reaction of S species.The combination merits of metal oxides and metal nitrides in one provide an effective strategy to improve the electrochemical performance of LSBs.In this work,defect design of niobium oxynitrides highly dispersed on graphene(NbON-G)is evaluated as effective trapper and catalyst for S species.Owning to the effective structural merits including enriched active sites,alleviated volume variation,defect modulated electronic property,and in-situ chemisorption and catalytic conversion of soluble lithium polysulfides(LiPSs),the LSBs with NbON-G modified separator show remarkably enhanced performance compared to NbN-G and Nb_(2)O_(5)-G.Surprisingly,even at low temperature of−40°C,the LSBs with NbON-G can operate for 1,000 cycles with 0.04%capacity decay per cycle(Rate:2 C).

All-Solid-State Thin-Film Lithium-Sulfur Batteries

Lithium-sulfur(Li-S)system coupled with thin-film solid electrolyte as a novel high-energy micro-battery has enormous potential for complementing embedded energy harvesters to enable the autonomy of the Internet of Things microdevice.However,the volatility in high vacuum and intrinsic sluggish kinetics of S hinder researchers from empirically integrating it into allsolid-state thin-film batteries,leading to inexperience in fabricating all-solid-state thin-film Li-S batteries(TFLSBs).Herein,for the first time,TFLSBs have been successfully constructed by stacking vertical graphene nanosheets-Li2S(VGsLi2S)composite thin-film cathode,lithium-phosphorous-oxynitride(LiPON)thin-film solid electrolyte,and Li metal anode.Fundamentally eliminating Lipolysulfide shuttle effect and maintaining a stable VGs-Li2S/LiPON interface upon prolonged cycles have been well identified by employing the solid-state Li-S system with an“unlimited Li”reservoir,which exhibits excellent longterm cycling stability with a capacity retention of 81%for 3,000 cycles,and an exceptional high temperature tolerance up to 60℃.More impressively,VGs-Li2S-based TFLSBs with evaporated-Li thin-film anode also demonstrate outstanding cycling performance over 500 cycles with a high Coulombic efficiency of 99.71%.Collectively,this study presents a new development strategy for secure and high-performance rechargeable all-solid-state thin-film batteries.

New Rare-Earth Containing (Sr_(1-y)Eu_y)_2Al_2Si_(10)N_(14)O_4 Phosphors for Light-Emitting Diodes

Remarkable progress was made in the development of white-light-emitting diodes （LEDs）. White LEDs provided a light element having a semiconductor InGaN light-emitting chip （blue or UV LEDs） and luminescent phosphors. Here we reported the sialon s-phase of （Sr,Eu）2A12Si10N14O4. Eu^2＋ activator ions that were substituted for the strontium site represented a new type of yeUow-green phosphor that could be excited by blue LEDs used for application in the fabrication of white LEDs.

In situ reaction mechanism of MgAlON in Al–Al2O3–MgO composites at 1700°C under flowing N2

The Al–AlO–MgO composites with added aluminum contents of approximately 0wt%, 5wt%, and 10wt%, named as M, M, and M, respectively, were prepared at 1700°C for 5 h under a flowing Natmosphere using the reaction sintering method. After sintering, the Al–AlO–MgO composites were characterized and analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results show that specimen Mwas composed of MgO and MgAlO. Compared with specimen M, specimens Mand Mpossessed MgAlON, and its production increased with increasing aluminum addition. Under an Natmosphere, MgO, AlO, and Al in the matrix of specimens Mand Mreacted to form MgAlON and AlN-polytypoids, which combined the particles and the matrix together and imparted the Al–AlO–MgO composites with a dense structure. The mechanism of MgAlON synthesis is described as follows. Under an Natmosphere, the partial pressure of oxygen is quite low; thus, when the Al–AlO–MgO composites were soaked at 580°C for an extended period, aluminum metal was transformed into AlN. With increasing temperature, AlOdiffused into AlN crystal lattices and formed AlN-polytypoids; however, MgO reacted with AlOto form MgAlO. When the temperature was greater than(1640 ± 10)°C, AlN diffused into AlOand formed spinel-structured AlON. In situ MgAlON was acquired through a solid-solution reaction between AlON and Mg AlOat high temperatures because of their similar spinel structures.

Microwave Assisted Sintering and Photoluminescence Properties of BaaSi6OleNe：Eu^2＋ Green Phosphors

Eu^2＋-doped Ba3Si6012N2 green phosphors were prepared by microwave assisted sintering method at 1275℃ for 4 h, while the counterparts using conventional solid-state reaction method were synthesized at temperature higher than 1300℃ and for to 10 h. Microwave assisted sintering could reduce the activation energy and enhance the diffu- sion rate, thus greatly improved the sintering. Moreover, the influence of Si3N4 content on phase formation, morphol- ogy, absorption, and quantum efficiency, and photoluminescence properties of phosphors were studied. As a result, the Ba3Si6OI2N2：Eu^2＋ samples sintered by microwave assisted sintering method have a higher phase purity and photo- luminescence intensity under ultraviolet excitation as compared with samples sintered in the conventional tube furnace The proposed method is a potential preparation method for the oxynitride phosphors with strong photoluminescence and high phase purity.

Molybdenum Oxynitride Atomic Nanoclusters Bonded in Nanosheets of N-Doped Carbon Hierarchical Microspheres for Efficient Sodium Storage

Transition metal nitrides have attracted considerable attention as great potential anode materials due to their excellent metallic conductivity and high theoretical specific capacity.However,their cycling performance is impeded by their instability caused by the reaction mechanism.Herein,we report the engineering and synthesis of a novel hybrid architecture composed of MoO2.0N0.5 atomic nanoclusters bonded in nanosheets of N-doped carbon hierarchical hollow microspheres(MoO2.0N0.5/NC)as an anode material for sodium-ion batteries.The facile self-templating strategy for the synthesis of MoO2.0N0.5/NC involves chemical polymerization and subsequent one-step calcination treatments.The design is benefi-cial to improve the electrochemical kinetics,buffer the volume variation of electrodes during cycling,and provide more interfacial active sites for sodium uptake.Due to these unique structural and compositional merits,these MoO2.0N0.5/NC exhibits excellent sodium storage performance in terms of superior rate capability and stable long cycle life.The work shows a feasible and effective way to design novel host candidates and solve the long-term cycling stability issues for sodium-ion batteries.

Synthesis of perovskite BaTaO_(2)N with low defect by Zn doping for boosted photocatalytic water reduction

Perovskite BaTaO_(2) N(BTON) is one of the most promising photocatalysts for solar water splitting due to its wide visible-light absorption and suitable conduction/valence bands,but it still confronts the challenge of high defect density causing decreased charge separation as well as photocatalytic activity.In this work,we develop a simple zinc doping strategy to greatly suppress its defect density and promote its water reduction performance.It is found that the defect formation on the nitrided Ba(Zn_(1/3-x)Ta_(2/3))O_(3-y)N_z(denoted as BZTON hereafter) will be greatly inhibited when the Zn-doped Ba(Zn_(1/3)Ta_(2/3))O_(3)(BZTO) oxide is used as the nitridation precursor.The structural characterizations and discussion demonstrate that the effective inhibition of Ta^(5+)into Ta^(4+)defects in BZTON mainly results from the easy reduction of zinc ions into metal and further the evaporation of zinc metal under the thermal ammonia flow.Interestingly,this simply doping methodology can be easily extended into the synthesis of SrTaO_(2) N(STON) with extremely low defect density,demonstrating its generality.Benefiting from the successful control to the defect density,the as-obtained BZTON photocatalyst exhibits remarkably promoted charge separation as well as water reduction activity to produce hydrogen with respect to the pristine BTON.Our work may provide an alternative avenue to prepare oxynitride semiconductors with reduced defect density for promoted solar energy conversion.

Synthesis and Characterization of Mesoporous Silicon Oxynitride MCM-41 with High Nitrogen Content

Mesoporous silicon oxynitrides MCM-41 were synthesized successfully. The resulting materials not only have high nitrogen contents and good structural characteristics of MCM-41 (high surface area, narrow pore size distribution and good order), but also are amorphous. The composition and structure of the materials were investigated by CNH element analysis, XPS, Si MAS NMR, XRD, HRTEM and N-2 sorption, respectively. Mesoporous silicon oxynitrides MCM-41 with a high nitrogen content are still non-crystal (amorphous).

Effect of the Fourth Element on Bonding of Silicon Nitride Ceramics with Y_2O_3-Al_2O_3-SiO_2 Glass Solders

Bonding of Si 3N 4 ceramic was performed with Y 2O 3 Al 2O 3 SiO 2(YAS) X glass solders,which were mixed with TiO 2 (YT) and Si 3N 4 (YN), respectively. The effects of bonding conditions and interfacial reaction on the joint strength were studied. The joint strength in different bonding conditions was measured by four point bending tests. The interfacial microstructures were observed and analyzed by SEM, EPMA and XRD. It is shown that with the increase of bonding temperature and holding time, the joint strength increases reaching a peak, and then decreases. When TiO 2 is put into YAS solder,the bonding interface with Si 3N 4/(Y Sialon glass+TiN)/TiN/Y Sialon glass is formed. When YAS solder is mixed with Si 3N 4 powder, the interfacial residual thermal stress may be decreased, and then the joint strength is enhanced. According to microanalyses, the bonding strength is related to interfacial reaction.

Silicon Nitride Etch via Oxidation Reaction in Fluorocarbon/Oxygen Plasma:A First-Principle Study

Conducting all-in-one etch process for 3D-NAND fabrication requires close etch rate(E/R)for SiO2 and Si3N4;however,to attain comparable and high etch rate for both materials is challenging.In this work,we performed first-principle studies on the etching mechanism of Si3N4 in fluorocarbon/oxygen plasma.The feasibility of using fluorocarbon/oxygen plasma to etch Si3N4 while attaining close E/R to SiO2 through the complementary nitride to oxynitiride(SiOxNy)transformation has been identified.Such transformation involves two stages:N atom elimination and Si-O bond formation.By modeling the essential chemical reactions on the Si3N4 surface,we shed light upon the underlying mechanisms behind both stages.We simulated the N-elimination reactions involving the formation and desorption of NO and FNO molecules as well as the substitution with F atoms.We found that N atoms can be eliminated by forming NO molecules,especially with the assistance of F-substitution in Si-N bond breaking.The predicted O-additive energies indicates that forming SiOxNy structure after N-elimination is possible.Following that,the dependency of chemistries favoring either high E/R or active SiOxNy formation on the fluorocarbon/oxygen ratio was discussed.We hope that the work will build a foundation for future studies on pursuing all-in-one ON etch process via the surface modifications.

Local oxynitriding of AZ31 magnesium alloy by atmospheric-pressure plasma treatment at room temperature

A surface-hardening treatment for AZ31 magnesium alloy using an atmospheric-pressure plasma jet(APPJ)at room temperature was developed.Magnesium is a potential engineering material because it is lightweight;however,magnesium alloys are difficult to heat-treat because of their low flaming temperature.Magnesium alloy specimens were irradiated with a localized atmospheric-pressure plasma jet generated by dielectric-barrier discharge for 180 s in air.The APPJ excited oxygen and nitrogen molecules in the ambient air,resulting in the formation of an oxynitrided layer;oxygen and nitrogen diffusion layer,on the surface of the magnesium alloy.The hardness and elemental distribution for the treated surface were examined.The top surface of the APPJ-treated magnesium alloy achieved a maximum hardness of 108 HV,which was~1.7 times greater than that of the untreated surface.Elemental analysis using an electron-probe microanalyzer revealed strong oxygen and nitrogen signals corresponding to the hardened region of the magnesium alloy,meaning that the hardness increased as a result of the formation of the oxynitrided layer.The proposed APPJ treatment is a promising approach for locally hardening magnesium alloys without using a heat treatment.

Valence modulated nickel oxynitride network as integrated bifunctional electrodes for enhanced energy storage

As promising electrode materials,transition metal oxides have attracted considerable attention owing to their excellent performance in electrochemical energy storage.However,their poor conductivity and fragile structure limit their practical application.In this study,a binder-free nickel oxide/oxynitride network(NiON WS)bifunctional electrodes with cation multivalent states that exhibit high energy storage performance were synthesized for the first time.The massive active sites,high specific surface areas,and multiple cation valence states of NiON WS were advantageous for electrochemical redox reaction during its application in supercapacitors(1283.5 mF cm^(-2))and lithium-ion batteries(1345.0 mA h g^(-1)).Particularly,the NiON WS based flexible asymmetric SCs exhibit excellent capacitance and energy densities.First-principle calculations were employed to study the mechanism of the electrochemical performance improvement of NiON WS.This study demonstrates the potential of transition metal oxides electrode with high capacity and activity for electrochemical energy storage and conversion.

Achieving photocatalytic water oxidation on LaNbON2 under visible light irradiation

LaNbON2 has narrow bandgap and wide visible-light absorption band, yet no photocatalytic water oxidation on LaNbON2 has been reported. By a post-annealing treatment in Ar, anion vacancies were brought into LaNbON2 as shown by EPR spectroscopy. These could act as donors in the semiconductor. And consequently the oxidative power of holes was enhanced as indicated by the difference between fermi level and valence band maximum（EF-EVBM） evaluated from valence band XPS. The annealed LaNbON2 photocatalyst acquired water oxidation ability for the first time, which was improved by combining CoOx as cocatalyst. Annealed LaNbON2 derived from La3NbO7 had smaller particle size, higher concentration of anion vacancies, bigger EF-EVBM and better performance for photocatalytic oxygen evolution reaction than LaNbON2 derived from LaNbO4.

Etching characteristics of thin SiON films using a liquefied perfluorocarbon precursor of C_6F_(12)O with a low global warming potential

Perfluorocarbon gas is widely used in the semiconductor industry.However,perfluorocarbon has a negative effect on the global environment owing to its high global warming potential(GWP) value.An alternative solution is essential.Therefore,we evaluated the possibility of replacing conventional perfluorocarbon etching gases such as CHF_3 with C_6F_(12)O,which has a low GWP and is in a liquid state at room temperature.In this study,silicon oxynitride(SiON) films were plasma-etched using inductively coupled CF4+C_6F_(12)O+O_2 mixed plasmas.Subsequently,the etching characteristics of the film,such as etching rate,etching profile,selectivity over Si,and photoresist,were investigated.A double Langmuir probe was used and optical emission spectroscopy was performed for plasma diagnostics.In addition,a contact angle goniometer and x-ray photoelectron spectroscope were used to confirm the change in the surface properties of the etched SiON film surface.Consequently,the etching characteristics of the C_6F_(12)O mixed plasma exhibited a lower etching rate,higher SiON/Si selectivity,lower plasma damage,and more vertical etched profiles than the conventional CHF_3 mixed plasma.In addition,the C_6F_(12)O gas can be recovered in the liquid state,thereby decreasing global warming.These results confirmed that the C_6F_(12)O precursor can sufficiently replace the conventional etching gas.

Resistance of Si_2N_2O ceramics to oxidation and erosion of molten silica

Si 2N 2O ceramics was fabricated from powder by hot pressing in N 2 atmosphere. The resistance of the ceramic sample to oxidation and erosion of molten silica was investigated. The bulk density and open porosity of the ceramic sample were measured according to the Archimedes principle in water. Then fracture surface of the sintered body was observed by SEM. The results and analysis indicate that the resistance of Si 2N 2O ceramics to oxidation and erosion of molten silica increases when its density increases and/or its open porosity decreases. Moreover, they also reveal that the oxidation process is an unsteady dispersing process with oxygen as the constant source, and the resistance to erosion of molten silica related to the quantity of grain boundary in unit surface area. The lowest mass gain is 2.4 g/m 2 after oxidizing at 1 000 ℃ for 100 h in air, while the lowest mass loss is 2.9 g/m 2 after 40 h erosion in molten silica.

Preparation and mechanical properties of Si_2N_2O ceramics

Si 2N 2O ceramics was fabricated from pre synthesized Si 2N 2O powder by the hot pressed sintering method. The results indicated that the highest relative density and hardness(HRA) of the sample are almost 100% and 93, respectively. Moreover, effects of some experimental parameters (such as the amount of sintering aid agent Y 2O 3, sintering time and temperature) on the density and microstructure of ceramics were investigated, and effects of the density and micro structure on some mechanical properties(HRA, σ f and K IC ) were also discussed.

Influence of Silicon Oxynitride on Slag Resistance of Al_2O_3-Si C-C Refractory

Silicon oxynitride was added in shaped Al_2O_3-SiC-C refractory material to improve the slag resistance in this paper.Optimum adding quantity of silicon oxynitride powder was also studied. The results show that the slag resistance of Al_2O_3-SiC-C shaped refractory is improved when 2% or 3% Si_2N_2O is added. A reasonable amount of Si_2N_2O added into Al_2O_3-Si C-C shaped refractory can produce silicon oxide into the slag, which can improve the viscosity of slag and prevent the slag erosion and penetration.

Origin of superior pseudocapacitive mechanism of transition metal nitrides

Large-scale deployment of Internet of Things (IoT),a revolutionary innovation for a better world,is hampered by the limitation of energy self-sufficiency.Constructing transition metal nitride (TMN)-based micro-supercapacitors is a possible solution by taking advantage of the high conductivity,large specific capacitance,and large tap density of the materials.However,the pseudocapacitive storage mechanism of TMNs is still unclear consequently impeding the design of microdevices.Herein,the functions and mechanism of TMNs with different metal oxynitride (TMNO_(x)) concentrations in pseudocapacitive electrodes are investigated systematically by in situ Raman scattering,ex situ X-ray photoelectron spectroscopy,as well as ion isolation and substitution cyclic voltammetry.It is found that the specific capacitances of TMNs depend on the TMNO_(x) concentrations and the N–M–O site is responsible for the large pseudocapacitance via the Faradic reaction between TMNO_(x) and OH^(-).Our study elucidates the mechanism pertaining to pseudocapacitive charge storage of TMNs and provides insights into the design and optimization of TMNO_(x) as well as other electrode materials for pseudocapacitors.