Search

The LiNbO3 (LN)-type oxynitrides, MnTaO2N and (1 - x)MnTaO2N-xMn4Ta2O9 were synthesized under high pressures and at high temperatures. The new LN-type oxynitride, Mn(Mn1/6Ta5/6)O2.5N0.5 (0.75MnTaO2N-0.25Mn4Ta2O9) could be obtained with trace impurities. In this compound, the displacement of B ion (Ta/Mn ion) from the center of the BX6 octahedron was smaller than that in other LN-type oxides containing Ta and/or Mn ions. This indicates that the displacement of Ta/Mn ion was reduced by doping with nitride ion. [ABSTRACT FROM AUTHOR]

A novel oxynitride, BaYSi2O5N, has been synthesized by a solid-state reaction method. Its crystal structure was determined by single-crystal X-ray analysis. Eu2+- and Ce3+-doped BaYSi2O5N exhibit broad blue emission with peaks around 459 and 412 nm under excitation at 250450 and 250370 nm, respectively. This is the first report on the synthesis of oxynitrides in the BaO-Y2O3-SiO2-Si3N4 system. [ABSTRACT FROM AUTHOR]

Tantalum nitride (Ta 3 N 5 ) has gained significant attention as a potential photoanode material, yet it has been challenged by material quality issues. Defect-induced trap states are detrimental to the performance of any semiconductor material. Beyond influencing the performance of Ta 3 N 5 films, defects can also accelerate the degradation in water during desired electrochemical applications. Defect passivation has provided an enormous boost to the development of many semiconductor materials but is currently in its infancy for Ta 3 N 5 . This is in part due to a lack of experimental understanding regarding the spatial and energetic distribution of trap states throughout Ta 3 N 5 thin films. Here, we employ drive-level capacitance profiling (DLCP) to experimentally resolve the spatial and energetic distribution of trap states throughout Ta 3 N 5 thin films. The density of deeper energetic traps is found to reach ∼2.5 to 6 × 10 22 cm -3 at the interfaces of neat Ta 3 N 5 thin films, over an order of magnitude greater than the bulk. In addition to the spatial profile of deep trap states, we report neat Ta 3 N 5 thin films to be highly n-type in nature, owning a free carrier density of ∼9.74 × 10 17 cm -3 . This information, coupled with the present understanding of native oxide layers on Ta 3 N 5 , has facilitated the rational design of a targeted passivation strategy that simultaneously provides a means for catalyst immobilization. Loading catalyst via silatrane moieties suppresses the density of defects at the surface of Ta 3 N 5 thin films by two orders of magnitude, while also reducing the free carrier density of films by over one order of magnitude, effectively dedoping the films to ∼2.40 × 10 16 cm -3 . The surface passivation of Ta 3 N 5 films translates to suppressed defect-induced trapping and recombination of photoexcited carriers, as determined through absorption, photoluminescence, and transient photovoltage. This illustrates how developing a deeper understanding of the distribution and influence of defects in Ta 3 N 5 thin films has the potential to guide future works and ultimately accelerate the integration and development of high-performance Ta 3 N 5 thin film devices.

This paper focuses on high-temperature tribotests of nanostructured Al–Cr-based oxynitride and oxide coatings. Pin-on-disk tribological tests were performed at temperatures in between room temperature and 800 °C, and the results compared to a conventional AlTiN coating. The AlCrN and AlCrON coatings showed good to acceptable wear resistance up to 600 °C while at 800 °C, both coating types failed. The new corundum-structured (Al,Cr) 2 O 3 oxide showed excellent wear performance up to 800 °C. Imaging and chemical analysis of the high-temperature wear tracks allowed for explaining the differences in the wear mechanisms. The ability of a coating to resist oxidation and to delay substrate oxidation, together with an excellent abrasional wear resistance, were identified as the major factors influencing wear rates under severe high-temperature conditions. [ABSTRACT FROM AUTHOR]

It is shown that today the main problem of SOI technology is the low reproducibility of parameters when using high-temperature technology of synthesis and detachment of mono Si layer in a hydrogen atmosphere. Physical basics of the methods for creating silicon-on-insulator (SOI) and gallium arsenide-on-insulator (GAOI) structures using different methods were considered in the paper. Major attention was paid to the ⪡DeleCut⪢ method (ion irradiated Deleted oxide Out), which is essentially a modification of the known ⪡SmartCut⪢ method and is intended to eliminate a lack of basic method. DeleCut method allows significantly reduce the annealing temperature and concentration of radiation defects in SOI and GAOI structures, decrease the thickness of the cut off layer of silicon or gallium arsenide and the transition layer between the SOI or GAOI layer and hidden oxide (oxynitride). Simultaneously, an increase in thickness uniformity of SOI or GAOI layers and dielectric (semiinsulaedr semiconductor) to several nanometers is achieved. [ABSTRACT FROM AUTHOR]

Novel oxynitride glass–ceramics with tremendously improved quantum yield and adjustable color coordinates were prepared with the conventional melt-and-quench method and subsequent annealing heat treatment. X-ray diffraction (XRD) and transmission electron microscopy (TEM) images revealed CaAl 2 Si 2 O 8 and Y 20 N 4 Si 12 O 48 crystalline phases were homogenously precipitated in the glass matrix. The optical absorption and photoluminescence (PL) spectrum measurements showed that a large portion of Eu 3 + ions were reduced into Eu 2 + which were crystallized into CaAl 2 Si 2 O 8 phase during the heat treatment by substituting Ca 2 + ions in them. Emission spectra evidently show that Eu 2 + and Eu 3 + ions were preferentially incorporated in CaAl 2 Si 2 O 8 and Y 20 N 4 Si 12 O 48 crystalline phases, respectively. This assignment was further supported by cation ionic radii and local charge balances, as well as defect chemistry considerations. The total emission intensity including both Eu 2 + and Eu 3 + ions was enhanced with increasing the annealing temperature, due to the conversion of Eu 3 + to Eu 2 + and the enhanced quantum efficiency of Eu 3 + in the crystalline phase as compared to the glass matrix. As a result, the quantum yields (QYs) of the glass–ceramics were also enhanced significantly from 2.07% (the precursor glass) up to 43.33% (the maximum of the glass–ceramics). The emission ratio of Eu 2 + /Eu 3 + changed from < 1.0 to > 4.0, which led this novel glass–ceramics with adjustable color coordinates ranging from red to blue controlled by varying the annealing temperature. [ABSTRACT FROM AUTHOR]

An oxynitride phosphor (Sr 1− x Ba x ) 2.97 SiO 3 N 4/3 :0.03Eu 2+ (SBSON) was synthesized by the solid-state reaction at 1550 °C for 4 h. XRD results show that the major phase of the synthesized phosphors is isostructural with Sr 3 SiO 5 when the content of Ba 2+ is not greater than 0.5. Through the doping of Ba 2+ ions, the particle morphology, luminescence intensities and thermal stability are all improved obviously. When the x equals 0.5 the luminescence intensity reaches maximum which is about 1.48 times as that of the phosphor free of Ba 2+ . The emission peaks can be tuned from 583 nm to 601 nm by adjusting Ba 2+ content. The doping of Ba 2+ can also prolong the average lifetime from 1482 to 2122 ns. With high emission intensity and thermal stability, this novel oxynitride phosphor SBSON shows potential application in white LEDs. [ABSTRACT FROM AUTHOR]

In this study, the main attempt is devoted to investigating the microstructure and electronic properties of AlCrO x N 1 − x films in a wide range of oxygen concentrations from 0 to 1. These oxynitride films were deposited by pulsed DC magnetron sputtering from Al 55 Cr 45 targets. Our results showed that films with x = O/(O + N) < 0.6, exhibit a cubic (B1) lattice with a well-developed columnar structure. The incorporation of oxygen into the films without any oxide segregation results in the formation of a substitutional AlCrO x N 1 − x solid solution and material system behaves like nitrides electronically. In the range of oxygen contents from 0.6 ≤ O/(O + N) < 0.97, coatings with fine columns, diffuse boundaries and high values of metal vacancies were formed. However, the B1 lattice survived despite the large proportion of oxygen. According to the structural and electronic properties of the corresponding layers, we assign this region to the formation of an amorphous phase and metastable monoxides with a B1 structure. Coatings with O/(O + N) ≥ 0.97 are electronically assigned to a solid solution of α -(Al,Cr) 2 (O 0.97 ,N 0.03 ) 3 with corundum lattice and finer columnar structure. [ABSTRACT FROM AUTHOR]

The thermal low-pressure oxynitridation of Si(100) in N2O has been studied for ultra-thin (<5 nm) SiOxNyfilms. The nitrogen concentration and depth profiles were accurately determined by secondary ion mass spectrometry. It has been found that small amounts of nitrogen uniformly distribute in the dielectrics, and the kinetics of the oxynitridation (i.e., thickness vs. time) can be accurately expressed as a logarithmic equation. Meanwhile, the electrical properties of the oxynitride films: the average breakdown equivalent fields of dioxide (EBD), the breakdown time (TBD), the fixed charge (Qf), and the interface state density (Dit) have been characterized and analyzed by the current–voltage (I–V), the time-dependent dielectric breakdown, the capacitance–voltage (C–V), and the conductance–frequency (G–W), respectively. The oxynitride films with EBD ≈ 15.46 MV cm−1and TBD ≈ 2.39 E4ms were prepared successfully by processing optimization. The result reveals that the thermal low-pressure oxynitridation is helpful to obtain excellent gate dielectrics with low interface state density (Ditwith an order from 2.0 E9to 3.0 E10 ev−1 cm−2). Such a result can be attributed to nitrogen incorporation and slow growth rate during low-pressure processes. It is concluded that the characteristics of the oxynitride films are suitable for applications in metal-oxide-semiconductor and nonvolatile memory devices. [ABSTRACT FROM AUTHOR]

With a theoretical maximum photocurrent of ca. 12.5 mA cm−2 under AM 1.5 G 100 mW cm−2 irradiation, the presently achieved plateau photocurrent of about 0.6 mA cm−2 on bare LaTiO2N photoanodes indicates the presence of serious charge transport limitations. Only recently, a plateau photocurrent of about 4 mA cm−2 was achieved on precious IrO2 modified LaTiO2N photoanodes prepared by a rather expensive and complex method, without discussing the intrinsic mechanism of improved photocurrents. In this study, by establishing highly crystalline porous LaTiO2N particles and superior inter-particle connectivity with reduced density of grain boundaries among the film particles, a record plateau photocurrent of 6.5 mA cm−2 on the Co3O4 modified LaTiO2N photoanodesis demonstrated under AM 1.5 G 100 mW cm−2 simulated sunlight. More broadly, this work shows the intrinsic requirements and significance of constituting (oxy)nitride particles for efficient charge transport and therefore desirable photoelectrochemical performances on the (oxy)nitride photoelectrodes, which have never been noticed and investigated before. With the obtained rules to follow are encouraging to explore the remaining substantial (oxy)nitride semiconductors as potential photoelectrodes for solar energy conversion. [ABSTRACT FROM AUTHOR]

Abstract: Lanthanum tantalum oxynitride (LaTaON2) powders were prepared by one-step flux method. LaTaON2 photoanodes, which are fabricated by using LaTaON2 powders, are found to exhibit photoelectrochemical activity for overall water splitting. The photocurrent for LaTaON2 photoelectrodes was ca. 120 μA cm−2 at 1.5 V vs. reversible hydrogen electrode (RHE) in 1 M NaOH aqueous solutions (pH = 13.6) under AM 1.5 G simulated sunlight irradiation (100 mW cm−2). The photocurrent of LaTaON2 photoelectrode from back-side illumination is much larger than that from front-side illumination, suggesting that the photoelectrochemical property is mainly limited by poor continuous electron transport in the bulk. Further efforts to ameliorate the electron transport in the bulk of LaTaON2 photoelectrodes are expected to significantly improve their photoelectrochemical performance. [Copyright &y& Elsevier]

The metal-free graphitic carbon nitride (g-C 3 N 4) with a series of merits like low cost, favorable stability, and controllable two-dimensional graphite-like structure, has been extensively studied for photocatalytic H 2 evolution. Composite engineering is regarded as one of effective strategies to adjust the kinetics of photogenerated carriers in g-C 3 N 4 for elevating its photocatalytic performance. Herein, the composite system of g-C 3 N 4 with oxynitride LaTiO 2 N was elaborately constructed for improving photocatalytic H 2 -evolution performance. With systematical characterizations, the partial cover of g-C 3 N 4 nanosheets on LaTiO 2 N (LaTiO 2 N@g-C 3 N 4) was verified and promoted the sufficient contact between g-C 3 N 4 and LaTiO 2 N, accompanied by the formation of the (oxy)nitride heterojunction. Benefited by the well-matched band structures for g-C 3 N 4 and LaTiO 2 N, the (oxy)nitride heterojunction strengthened the separation of photogenerated carriers and therefore enhanced the photocatalytic performance of g-C 3 N 4. This work gives more insight in composite engineering on g-C 3 N 4 , and also provides feasible guidelines for designing g-C 3 N 4 -based photocatalysts towards improving photocatalytic performance. [Display omitted] • Composites of g-C 3 N 4 and LaTiO 2 N were created to promote photocatalytic H 2 evolution. • g-C 3 N 4 nanosheets partially covered the surface of LaTiO 2 N (LaTiO 2 N@g-C 3 N 4). • (Oxy)nitride heterojunction between g-C 3 N 4 and LaTiO 2 N was formed. • Separation of photogenerated carriers was enhanced by (Oxy)nitride heterojunction. [ABSTRACT FROM AUTHOR]

• Recent photocatalytic progress of the mixed anion materials was discussed. • Mechanochemical doping and hydrothermal/solvothermal process were described. • Mixed anions materials solve environmental remediation and energy related problem. • Use of mixed anions for pollutants removal, CO 2 reduction and water splitting. Rapid growing energy demands owing to the reduction of fossil fuels as well as environmental pollution call for renewable, environment-friendly energy sources. Photocatalysis has widely applied for water splitting to generate H 2 , oxygen evolution, organic synthesis, pollutants degradation, and much more. Today, various multi-anion materials are used, which are synthesized via easy and environment-friendly methods. The multi-anion materials mainly consist of N/C/O, S/O, N/F/O, and N/O, which shows excellent photocatalytic activity. Also, multi-anion contains metal cations and two anionic species. Multi-anion photocatalysts have vast absorption bands and visible-light absorption efficiency. This review discusses the basic information of multi-anion compounds like synthesis, physical and chemical properties. Meanwhile, some research progress of multi anion materials was also given for CO 2 reduction, water splitting, and pollutants removal. [Display omitted] [ABSTRACT FROM AUTHOR]

The comparison for the relative energies of related reactions including NO x +H 2 O and cracking NO x (Here, N 2 O 3 is trans– cis -N 2 O 3 , N 2 O 4 is cis -N 2 O 4). [Display omitted] • The high-pressure limiting rate constant and pressure-dependent rate constant were respectively calculated for related reactions of NO x with H 2 O and cracking NO x. • The fitting results were in well agreement with corresponding calculating data via two kinds of validation. • The influence of anharmonicity was prominent and shouldn't be overlooked for related cracking, isomerizing and bimolecular reactions of NO x. Reaction mechanism and anharmonicity involving in NO x were researched, in which included decomposition (NO x), isomerization (N 2 O 3 and N 2 O 4) and bimolecular reactions (NO x + H 2 O). Specially, high-pressure limiting and pressure-dependent rate constant were respectively calculated by TS and RRKM-ME theory. And, high-pressure limiting data were in well agreement with corresponding calculating results via two kinds of validation. Moreover, N 2 O 3 and N 2 O 4 were not steady, and products of N 2 O 3 or N 2 O 4 with H 2 O were not steadier than that of N 2 O 5. Therefore, N 2 O 5 was the key specie for NO x to be absorbed by H 2 O. Furthermore, anharmonic effect was prominent and shouldn't be overlooked. [ABSTRACT FROM AUTHOR]

● We developed the oxide/metal/oxide based inverted organic solar cell. ● InGaON (indium oxide and gallium nitrate) co-sputtered on the glass substrate with thermally evaporated Ag–Ti interlayer was used to fabricate the oxide/metal/oxide electrode. ● The electrode was subjected to electrical, optical, and mechanical testing. ● The inverted organic solar cell was developed using the InGaON/Ag–Ti/InGaON cathode. The inverted organic solar cell (IOSC) supported on an optically transparent and mechanically flexible oxynitride/metal/oxynitride substrate is receiving increasing attention owing to its light weight, flexible, and cost-effective design, compared to the conventional oxide-based solar cells. To develop an efficient IOSC, technical issues related to charge carrier transport and the transmittance of the conventional oxide electrode need to be solved. Herein, we report a highly transparent cathode for a highly efficient inverted organic solar cell using InGaON/Ag–Ti/InGaON multilayer electrodes. The In 2 O 3 and GaN targets are co-sputtered to fabricate the multicomponent conductive oxynitride films. The sheet resistance of InGaON in optimized sputtering conditions is about 53.63 Ω/□, with the transmittance of 88.12%. The optimal InGaON/Ag–Ti/InGaON configuration (35/12/35 nm) showed the low sheet resistance of 5.7 Ω/□, and higher transmittance of about 96.8% as a whole InGaON/Ag–Ti/InGaON electrode. The multilayer electrode showed superior mechanical property in bending and twisting for 10,000 cycles with no resistance change. Furthermore, the inverted organic solar cell with the deposited layers of InGaON/Ag–Ti/InGaON–ZnO–Active layer–MoO 3 –Ag exhibited the higher power conversion efficiency of 8.63%, indicating that the InGaON/Ag–Ti/InGaON cathode is a promising candidate for substitution for the conventional oxide electrode. [ABSTRACT FROM AUTHOR]

Abstract: The superconducting transition temperature of niobium silicon oxynitride (Nb0.87Si0.09□0.04)(N0.87O0.13) exhibits a gradual reduction from 16.8K to around 11K under an increasing applied magnetic field of up to 14T. This relatively small T c reduction under an applied magnetic field suggests a robustness of its superconducting behavior in comparison to that in the parent niobium oxynitride. It was similar to the flux pinning effect observed in the large magnetic hysteresis of the niobium-silicon oxynitrides in our previous study. Both Si K-edge XANES and 29Si MAS-NMR indicated that the local structure of pinning centers around the silicon atoms close to cationic vacancies was similar to that of Si in amorphous SiO2 in the rock-salt structure of niobium oxynitride. [Copyright &y& Elsevier]

Abstract: Hardness, oxidation resistance and adhesion have traditionally been the most important parameters for material selection and optimization of hard, wear resistant coatings. More recently, thermal conductivity has become a focus of research, as it has the potential to have a significant effect on coating performance. Even though new experimental methods have become available to characterize thermal conductivity, recent studies focused on existing material systems, and there have been few attempts to design coating thermal conductivity for specific applications. We study thermal conductivity of arc evaporation oxynitride coatings with the composition CrN1−xOx and TiN1−xOx (x=0 … 0.4). With increasing substitution of nitrogen by oxygen, thermal conductivity could gradually be reduced from 9Wm−1 K−1 to 2.5Wm−1 K−1 in CrN1−xOx and from 35 to 5Wm−1 K−1 in TiN1−xOx. A model that assumes a constant phonon scattering cross-section of the oxygen concentration can explain the observed functional relationship. Other properties such as thermal stability, oxidation resistance and hardness of these oxynitrides show little variation with oxygen concentration, clearing the way to design functional coatings with specific thermal properties. [Copyright &y& Elsevier]

Abstract: Silicon (Si) and yttrium (Y) are believed to have a strong influence on functional properties of oxynitrides due to their effects in the growth process and incorporation in solid solution phases. It is worthwhile noting that the presence of these elements is strongly active for controlling structural evolution during the growth. The aim of this work is to systematically study the microstructural development and mechanical properties of (Al,Cr,Si/Y)O x N1− x oxynitride films as a function of Si and Y contents. Our results show that Si and Y have a different mechanism for incorporation into the oxynitride films. According to the TEM, XRD, and XPS results a substitutional role of yttrium is suggested for the investigated coatings, whereas silicon tends to form an amorphous glassy phase. Such oxynitride layers with cubic structure (fcc-B1) meet an enhanced structural stability by the incorporation of both silicon and yttrium. As a result, the nitride growth regime is extended in the range of O/(O+N)≤0.80. On the other hand, they hinder the formation of corundum phase in the predominant oxide regime (O/(O+N)≥0.98) suggesting retarded diffusional processes with the presence of such alloying elements (i.e. Si and Y) in the deposition flux. Additionally, the Y-containing oxynitrides demonstrate a greater nano-hardness for all growth regimes. [Copyright &y& Elsevier]

We have investigated the local luminescence properties of Eu-doped CaAlSiN3 by using low-energy electron beam (e-beam) techniques. The particles yield broad emission centered at 655 nm with a shoulder at higher wavelength under light excitation, and a broad band around 643 nm with a tail at 540 nm under e-beam excitation. Using cathodoluminescence (CL) in a scanning electron microscope (SEM), we have observed small and large particles, which, although with different compositions, exhibit Eu2+-related emissions at 645 and 635 nm, respectively. Local CL measurements reveal that the Eu2+ emission may actually consist of several bands. In addition to the red broad band, regularly spaced sharp peaks have been occasionally observed. These luminescence variations may originate from a variation in the composition inside CaAlSiN3. [ABSTRACT FROM AUTHOR]

Abstract: Blue-emitting Sr1−x Eu x Si9Al19ON31 phosphors were synthesized at 1800°C for 2h under 1MPa N2 by using the gas-pressure sintering method (GPS). The microstructure, photoluminescence (PL) properties of the prepared phosphors were investigated. Under the 290nm excitation, broad PL emission bands with peak positions at 448–490nm were detected. The concentration quenching was not observed owing to the large distance betweenEu2+ ions that made the nonradiative energy transfer between neighboring Eu2+ ions difficult. The blue phosphor generally showed a small thermal quenching at low Eu2+ concentrations. The absorption and external quantum efficiency of the synthesized Sr0.5Eu0.5Si9Al19ON31 were 85% and 62% upon the 365nm excitation, respectively. The interesting PL results indicate that Sr1−x Eu x Si9Al19ON31 has great potentials as a blue phosphor for white LEDs applications. [Copyright &y& Elsevier]

Ein edelmetallfreier Elektrokatalysator wurde für die Sauerstoffreduktionsreaktion entwickelt. Kohlenstoff ‐ fixiertes Cobalt ‐ Molybdän ‐ Oxynitrid wurde einfach durch Imprägnierung mit anschließender thermischer Ammonolyse hergestellt. Die elektrokatalytische Aktivität des Oxynitrids kam in 0.1 M KOH ‐ Lösung fast der von Platin gleich. Katalysatorstruktur und ‐ valenz wurden mithilfe komplementärer lokaler und Volumensonden charakterisiert. [ABSTRACT FROM AUTHOR]

Abstract: The relative sensitivity factor (RSF) plays a critical role in the quantification of nitrogen concentration in oxynitride gate oxide measured using secondary ion mass spectrometry (SIMS). The RSF depends primarily on the matrixes where the nitrogen resides under conditions in which the parametric settings of the SIMS equipment remain unchanged. In this article, different types of oxynitride dielectric films have been prepared under several different fabrication processes including decoupled plasma nitridation, thermal nitridation by nitric oxide (NO) and nitrous oxide (N2O), which resulted in the formation of significantly different chemical bonding and micro-structures for the oxynitride. The nitrogen RSF values of these oxynitride films were determined using the ratio of the species SiN− and 30Si− from the Time-of-Flight SIMS. It was found that the overall RSF values from the point-by-point algorithm ranged from 1.15×1021 to 2.41×1021 atoms/cm3. These account for about 2 times the difference in the RSF values. [Copyright &y& Elsevier]

Abstract: SrTaO2N prepared by a citrate route was capsule hot isostatic press sintered at 196MPa for 3h at 1200, 1400 and 1600°C. Densification over 80% was attained for all the sintered bodies with partial reduction, which was observed as a change of color from brown to dark gray. Exaggerated grain growth was observed with some amount of open pore for the product sintered at 1400°C. The sample was successfully returned to the brown insulator color after annealing in ammonia flow at 1000°C. The resultant SrTaO2N ceramics exhibited a considerably high relative dielectric permittivity of 7.8×103 at 102 Hz. [Copyright &y& Elsevier]

Abstract: Perovskite Laph name="sbnd" />Olms have been grown by radio frequency magnetron sputtering from a LaTiO2N target. With a very low base pressure in the deposition chamber, two types of films can be obtained: colored oxynitride LaTiO2N films when nitrogen gas is introduced during sputtering or black N-doped LaTiO3 films when deposition is performed in pure argon. On SrTiO3 (001) substrate heated at 750°C, LaTiO2N films are epitaxially grown, while N:LaTiO3 films are poorly crystallized. With a higher base pressure in the deposition chamber, transparent La2Ti2O7 films are produced. They are (012) textured on (001) SrTiO3 substrate. As observed during the reactive sputtering of metallic targets, the evolution of the deposition rate and the nitrogen content in films according to the N2 percentage in the plasma is abrupt. [Copyright &y& Elsevier]

Thin silicon dioxide films nitrided in N2/NO/O2 atmosphere at different temperature and NO/O2 flow ratio were investigated by time of flight secondary ion mass spectrometry (ToF-SIMS) using negative acquisition mode and Cs+ sputtering at low energy. The N depth distributions obtained by the ToF-SIMS profiles were compared with the correspondent N1s peaks acquired in X-ray photoelectron spectroscopy, demonstrating that the gradient in ion yield which occurs at the interface using these measurement conditions can be useful to quantify the amount of nitrogen placed exactly at the interface. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: This study concerns the use of reactive magnetron sputtering to prepare (TiVCrZrTa)-based oxide and oxynitride films. (TiVCrZrTa)1−x O x and (TiVCrZrTa)1−x−y N y O x films were prepared, and were found to be amorphous and free of multi-phase structure. Cations and anions in such structures were arranged in a random homogeneous dispersion. The introduction of nitrogen atoms into (TiVCrZrTa)1−x O x yields (TiVCrZrTa)1−x−y N y O x , which has a reduced oxidation state and thus, an increased number of the valence electrons. The (TiVCrZrTa)1−x−y N y O x film is an n-type semiconductor, with an indirect band gap of 1.95eV, and a carrier concentration (N) and conductivity (σ) of 1.01×1019 cm−3 and 2.75×10−2 (Ωcm)−1, respectively. [Copyright &y& Elsevier]

Recently, (Ga1-xZnx)(N1-xOx) has gained widespread attention as a comparatively high efficiency photocatalyst for visible-light-driven overall water splitting. Despite significant gains in efficiency over the past several years, a majority of the photogenerated carriers recombine within bulk powders. To improve the photocatalytic activity, we used an epitaxial casting method to synthesize single-crystalline, high surface area (Ga1-xZnx)(N1-xOx) nanotubes with ZnO compositions up to x=0.10. Individual nanotubes showed improved homogeneity over powder samples due to a well defined epitaxial interface for ZnO diffusion into GaN. Absorption measurements showed that the ZnO incorporation shifts the absorption into the visible region with a tail out to 500 nm. Gas chromatography (GC) was used to compare the solar water splitting activity of (Ga1-xZnx)(N1-xOx) nanotubes (x=0.05-0.10) with similar composition powders. Cocatalyst decorated samples were dispersed in aqueous solutions of CH3OH and AgO2CCH3 to monitor the H+ reduction and H2O oxidation half reactions, respectively. The nanotubes were found to have approximately 1.5-2 times higher photocatalytic activity than similar composition powders for the rate limiting H+ reduction half reaction. These results demonstrate that improvements in homogeneity and surface area using the nanotube geometry can enhance the photocatalytic activity of GaN:ZnO for solar water splitting. [ABSTRACT FROM AUTHOR]

Abstract: A new precursor route to prepare calcium tantalum oxynitride (CaTaO2N) was explored in an attempt to improve the photocatalytic activity for H2 evolution from water under visible light. CaTaO2N catalysts were prepared using either a layered metal oxide (e.g., RbCa2Ta3O10 or HCa2Ta3O10) or a bulk-type Ca-Ta oxide prepared by the polymerized complex (PC) method. CaTaO2N samples prepared from the layered oxides had a less-aggregated morphology and a bluer absorption edge than an analog from a PC-derived precursor, in addition to a lower density of anionic defects. Samples prepared from the layered oxide also showed an enhanced photocatalytic activity for H2 evolution from an aqueous methanol solution under visible light (λ >420nm), primarily because of their lower density of anionic defects and the enhanced driving force for surface redox reactions that resulted from their blue-shifted absorption edge. [Copyright &y& Elsevier]

We present experimental evidence of a thermally activated transformation of negative-bias-temperature-stress-induced transient hole trapping at preexisting oxide traps into more permanent trapped holes in the ultrathin oxynitride gate p-MOSFET. The transformation is also shown to correlate with the generation of stress-induced leakage current, indicating that it is one of the key mechanisms of bulk trap generation. A similar observation (reported elsewhere) applies to the \HfO2 gate p-MOSFET, implying that the observed hole-trap transformation is a common mechanism for bulk trap generation across different gate oxide technologies. The results further imply that preexisting oxide defects, usually deemed irrelevant to negative-bias temperature instability, have a definite role on long-term device parametric drifts. [ABSTRACT FROM PUBLISHER]

Abstract: Coatings of (Cr x Al1− x ) δ (O1− y N y ) ξ with 0.33⩽ x ⩽0.96, 0⩽ y ⩽1 and 0.63⩽ δ/ξ ⩽1.30 were deposited using cathodic arc evaporation in N2/O2 reactive gas mixtures on 50V negatively biased WC–10wt.% Co substrates from different Cr and Al alloys with three different Cr/Al compositional ratios. For N2 <63% of the total gas, ternary (Cr,Al)2O3 films containing <1at.% of N forms; as determined by elastic recoil detection analysis. Increasing the N2 fraction to 75% and above results in formation of quaternary oxynitride films. Phase analyses of the films by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy show the predominance of cubic Cr–Al–N and cubic-(Cr,Al)2O3 solid solutions and secondary hexagonal α-(Cr,Al)2O3 solid solution. High Cr and Al contents result in films with higher roughness, while high N and O contents result in smoother surfaces. Nanoindentation hardness measurements showed that Al-rich oxide or nitride films have hardness values of 24–28GPa, whereas the oxynitride films have a hardness of ∼30GPa, regardless of the Cr and Al contents. Metal cutting performance tests showed that the good wear properties are mainly correlated to the oxygen-rich coatings, regardless of the cubic or corundum fractions. [Copyright &y& Elsevier]

Abstract: The hydrodeoxygenation of guaiacol (2-methoxyphenol) has been studied in a batch reactor over alumina- and SBA-15 silica-supported molybdenum nitride catalysts at 300°C and 5MPa of hydrogen pressure. The catalysts were prepared by nitriding supported Mo oxide precursors with ammonia gas or nitrogen–hydrogen mixtures via temperature-programmed reaction. The alumina-supported catalysts had a higher activity relative to the SBA-15 silica-supported catalysts which was essentially due to catechol production, an effect of the alumina support. The SBA-15 silica-supported catalysts transformed guaiacol directly to phenol by demethoxylation without noticeable catechol production. On both supports, nitridation by ammonolysis increased the activity by a factor of ∼1.1 relative to nitridation by nitrogen–hydrogen. On SBA-15, ammonolysis preferentially produced the γ-Mo2N phase while the N2/H2 mixture produced the β-Mo2N0.78 phase. The incorporation of Co led to a marginal improvement in exposed Mo species but generally had a diminishing effect on HDO activity. The lack of catechol production using the SBA-15 silica support is important in minimizing coking reactions and also opens up possibilities for utilizing silica supports with highly controlled pore sizes to possibly influence product distribution in HDO of more diverse feed streams derived from biomass conversion processes. [Copyright &y& Elsevier]

Abstract: Oxynitrides with the nominal composition LaTiO2N were prepared from a La2Ti2O7 precursor by thermal ammonolysis of the oxide under an NH3 flow for different durations t (4 – 30h). X-ray diffraction (XRD) indicated that phase-pure LaTiO2N samples were obtained when t ≥ 13h. The material was further characterised by scanning electron microscopy (SEM), surface area measurements based on the BET method, thermogravimetric analysis (TGA) and UV-visible diffuse reflectance spectroscopy (DRS). The powders displayed an increased crystallite size and a decreased surface area with increasing t. The ratio of N/(N+O) increased with t from 0.22 – 0.27. Correlated to this nitrogen increase, a small variation of the bandgap energy was observed from 2.19 to 2.12eV with t. All LaTiO2N samples oxidised H2O into O2 in the presence of an electron acceptor (Ag+). The O2 evolution was increased from 12μmol/h (t = 13h) to 22 – 24μmol/h (16h ≤t ≤ 30h). It was found that the nitrogen content and the amount of defects played a key role in the photocatalytic O2 evolution. [Copyright &y& Elsevier]

A general physicochemical model describing the reactive sputtering process of metal targets in a medium of argon, nitrogen, and oxygen has been developed. The model is based on a surface chemical reaction of the oxynitride film formation that proceeds under the conditions of nonisothermal working surfaces of the sputtering system. A system of algebraic equations has been obtained for analytical description of the model and solved numerically for titanium oxynitride. [ABSTRACT FROM AUTHOR]

Abstract: Amorphous alumino–silicophosphate materials containing up to 1.70wt.% nitrogen have been successfully prepared by aluminium nitride solution in Na–Li–Si–Al–P–O melts at 850°C thus preventing phosphorus volatilisation. Although the solubility limit for nitrogen in these glasses was limited to 8.31wt.%, the presence of nitrogen in the materials greatly increases their glass transition temperatures, suppresses the devitrification and has a significant effect on their melting behaviour. Comparative analysis of Raman spectra for the oxide and oxynitride glasses shows the substitution of P–O–P linkages by PP linkages while tri-coordinated nitrogen bridges were not detected. The attendant increase in network connectivity arising from such a substitution is responsible for the increase in glass transition temperature when nitrogen substitutes for oxygen. [Copyright &y& Elsevier]

Abstract: The synthesis of a polycrystalline powder sample of iron doped orthorhombic titanium oxynitride, Ti2.92Fe0.01O4.02N0.98, on the scale of 0.7g has been achieved. This was conducted by the unusual route of delamination from a steel substrate of a thin film deposited using atmospheric pressure chemical vapour deposition. The structure of the titanium oxynitride is presented, determined from a combined analysis of X-ray and neutron powder diffraction data. The use of neutron diffraction allows the position of the oxygen and nitrogen ions in the material to be reported unambiguously for the first time. In this study Ti2.92Fe0.01O4.02N0.98 is found to crystallise in the Cmcm space group, iso-structural pseudobrookite, with lattice parameters a=3.81080(6)Å, b=9.6253(2)Å, and c=9.8859(2)Å, and contains partial oxygen–nitrogen ordering. Of the three anion sites in this structure one is exclusively occupied by oxygen, while the remaining two sites are occupied by oxygen and nitrogen in a disordered manner. Testing indicates that this iron doped titanium oxynitride is a metastable phase that decomposes above 700°C into TiN and TiO2, the thermodynamic products. [Copyright &y& Elsevier]

Abstract: Oxynitride phosphor powders comprising of CaSi2O2N2 doped with Tb3+ were successfully synthesized using a high-temperature solid-state reaction method. The experimentally determined photoluminescence (PL) properties of the produced phosphors meet the requirements of 2D/3D plasma display panels (PDPs). In particular, under the excitation of vacuum ultraviolet (VUV) synchrotron radiation and ultraviolet (UV) irradiation, emission peaks corresponding to the 5D3→7F J (J=6, 5, 4, 3) and 5D4→7F J (J=6, 5, 4, 3) transitions of Tb3+ ions were recorded. Monitoring the 5D4→7F5 emission of Tb3+ at 545nm, the excitation bands were assigned to the host-related absorption as well as the 4f–5d (fd) and the 4f–4f (ff) transitions of Tb3+. The produced phosphors can be efficiently excited at 147nm, and have an adequately short decay time (τ 1/10=1.14ms). [Copyright &y& Elsevier]

Abstract: The article reports on dc pulsed reactive sputtering of two-phase single layer Al-O-N nanocomposite films using dual magnetron in a mixture of N2 +O2 with pulsed inlet of oxygen. Two kinds of nanocomposite films were sputtered: (1) nc-AlN/a-(Al-O-N) film and (2) nc-(γ-Al2O3)/a-(Al-O-N) nanocomposite film; here nc- and a- denotes the nanocrystalline and amorphous phase, respectively. The transition from the nc-AlN/a-(Al-O-N) nanocomposite to the nc-(γ-Al2O3)/a-(Al-O-N) nanocomposite was controlled by the length of the period of oxygen pulses TO2. It was found that both nanocomposites are highly elastic films with relatively high hardness H=15 to 20GPa, low effective Young''s modulus E⁎ satisfying the condition that the ratio H/E⁎ >0.1, high elastic recovery We >60% and high resistance to cracking in bending. Correlations between the film structure and its mechanical properties are discussed in detail. [Copyright &y& Elsevier]

Abstract: Novel Eu2+-doped Ca2AlSi3O2N5 phosphors with a general formula of Eu x Ca2−x AlSi3O2N5 were successfully prepared via a solid-state reaction method under a nitrogen atmosphere. The produced phosphors were effectively excited by UV–vis light in the wavelength range between 250 and 400nm, and featured an intense green emission band which peaked at about 500nm. The emission spectra featured a red-shift over increasing Eu2+ content and the temperature of heat treatment. The maximum intensity of emission was obtained for x =0.014 and heat treatment at 1450°C. The photoluminescence properties of the produced Ca2AlSi3O2N5:Eu2+ phosphors qualify them for consideration in potential use as green phosphors in UVLED-based white LED. [Copyright &y& Elsevier]

Studies have suggested that interface state generation under negative-bias temperature (NBT) stress results in positive oxide charge trapping. The latter is ascribed to the trapping of hydrogen species, from Si–H bond dissociation, in the oxide bulk. In this paper, we present evidence from dynamic NBT instability showing no apparent relationship between the two degradation mechanisms. The level of positive oxide trapped charge is shown to remain constant despite a nonnegligible increase of threshold voltage Vt shift due to interface state generation. This observation implies that Si–H bond dissociation did not result in any significant positive oxide trapped charge, and that the latter is due to a different mechanism (e.g., hole trapping at oxygen vacancies). The inference is supported by results from channel hot-hole stress, which is known to dissociate Si–H bonds but did not increase the level of positive oxide trapped charge. Possible reasons for the difference between previous and current studies are discussed. We also examine the observation on the “universal scalability” of Vt drift curves from different stress conditions, as explained by E^\prime - Pb coupling, i.e., Si–H bond dissociation is driven by hole trapping at nearby oxygen vacancies. We revisit an earlier observation that shows that such scalability only holds in the initial stage when positive oxide charge trapping is dominant, and that the scaled Vt drift curves eventually diverge in the later stage. Further evidence shows that the divergence is caused by interface state generation proceeding at a faster rate compared to positive oxide charge trapping. The result confirms that a part of interface degradation proceeds independently of positive oxide charge trapping. [ABSTRACT FROM AUTHOR]

Abstract: A series of novel nitrided tantalophosphates has been prepared by nitridation of X-ray amorphous TaPO5 precursors under ammonia flow. By varying the nitridation temperature, amorphous TaPO5−x N2x/3 (1.6< x <4.1) oxynitrides were obtained with different nitrogen contents (N wt.%=5–15). The most relevant features of this oxynitride series are as follow: (i) specific surface areas higher than 150m2 g−1, (ii) yellow to orange colors depending on nitrogen contents and (iii) formation of a solid solution with variable nitrogen and oxygen contents. The precursors and corresponding oxynitrides have been characterized by several techniques including X-ray diffraction, oxygen/nitrogen elemental analyses, BET analysis, UV–vis spectrophotometry, thermal analysis, SEM, DRIFT and NMR analyses. [Copyright &y& Elsevier]

Abstract: MSi2O2−δ N2+2/3δ :Eu2+ (M=Sr, Ba) phosphors were prepared through a two-step solid state reaction. XRD results reveal that the samples are nitrogen-rich phase. The photoluminescence results show that the MSi2O2−δ N2+2/3δ :Eu (M=Sr, Ba) phosphors can be excited by UV and blue light. The critical concentrations of Eu2+ are 5mol% and 4mol% for MSi2O2−δ N2+2/3δ :Eu (M=Sr, Ba), respectively. With an increase of the Eu2+-concentration, the emission color of SrSi2O2−δ N2+2/3δ :Eu can be tuned from green to yellow. Under the excitation of low voltage electron beams (1–3kV), the MSi2O2−δ N2+2/3δ :Eu (M=Sr, Ba) phosphors exhibit green and cyan emission, respectively. The emission intensity increases with the increasing of accelerating voltage and filament current. Due to the excellent stability, good CIE chromaticity and high color purity, MSi2O2−δ N2+2/3δ :Eu (M=Sr, Ba) phosphors may have potential application in the field emission displays. [Copyright &y& Elsevier]

Abstract: Two new oxynitride double perovskites of composition Sr2FeMoO6−x N x (x=0.3, 1.0) have been synthesized by annealing precursor powders obtained by citrate techniques in flowing ammonia at 750°C and 650°C, respectively. The polycrystalline samples have been characterized by chemical analysis, x-ray and neutron diffraction (NPD), Mössbauer spectroscopy and magnetic measurements. They exhibit a tetragonal structure with a=5.5959(1)Å, c=7.9024(2)Å, V=247.46(2)Å3 for Sr2FeMoO5.7N0.3; and a=5.6202(2)Å, c=7.9102(4)Å, V=249.85(2)Å3 for Sr2FeMoO5N; space group I4/m, Z=2. The nitridation process seems to extraordinarily improve the long-range Fe/Mo ordering, achieving 95% at moderate temperatures of 750°C. The analysis of high resolution NPD data, based on the contrast existing between the scattering lengths of O and N, shows that both atoms are located at (O,N)2 anion substructure corresponding to the basal ab plane of the perovskite structure, whereas the O1 site is fully occupied by oxygen atoms. The evolution of the 〈Fe–O〉 and 〈Mo–O〉 distances suggests a shift towards a configuration close to Fe4+(3d 4, S=2):Mo5+(4d 1, S=1/2). The magnetic susceptibility shows a ferrimagnetic transition with a reduced saturation magnetization compared to Sr2FeMoO6, due to the different nature of the magnetic double exchange interactions through Fe–N–Mo–N–Fe paths in contrast to the stronger Fe–O–Mo–O–Fe interactions. Also, the effect observed by low-temperature NPD seems to reduce the ordered Fe moments and enhance the Mo moments, in agreement with the evolution of the oxidation states, thus decreasing the saturation magnetization. [Copyright &y& Elsevier]

Abstract: The influence of oxygen content on the properties of cathodic arc-deposited AlCr(OxN1−x) coatings has been studied. All samples were prepared in a nitrogen-rich mixture of N2 and O2 at 550°C using lateral rotating arc cathodes (LARC) technology together with a pulsed bias voltage. The obtained coatings were characterized by various techniques including XRD, EPMA, TEM, pin-on-disk wear tests and nanoindentation. The results obtained allow to classify the coatings into three groups with respect to their microstructure, mechanical properties and oxygen content, x. For the first group of samples with x≤0.6, single-phase films of (Al,Cr)OxN1-x with fcc lattice were obtained, with well-developed columnar structure and a hardness of 30 to 33GPa. In the second group, a diffuse columnar structure was observed while the fcc lattice was still present despite the large proportion of oxygen, 0.60.97, where a well-crystalline α-(Al,Cr)2O3 corundum phase was observed and the hardness increased again to 28GPa. Our results indicate that the second group of coatings is metastable and after heat treatment transforms to a composite of cubic oxynitride and corundum oxide. Both friction and wear of samples from the entire investigated compositional range were studied at room temperature and 600°C. The low wear rates observed for the oxynitride coatings underline their potential for use in turning and milling applications. [Copyright &y& Elsevier]

Crystal structure was refined on Sr-Nb and Sr(La)-Nb oxynitride perovskites prepared through citrate route by using neutron diffraction. The former had the composition of SrNbO2.11N0.89 and crystallized in I4/mcm with a = 0.57099(2) nm, c = 0.81015(5) nm having excess oxide ions in apical 4a site around Nb being compared to the cis-TaO4N2 octahedra in SrTaO2N. The latter crystallized in the same space group with Sr0.81La0.19 having a = 0.57126(3) nm, c = 0.81055(6) nm. It was assumed that Sr0.81La0.19O1.90N1.10 has similar O/N occupancy in both apical 4a and equatorial 8h sites. The La substitution made the O/N occupancies equilibrated around Nb. The niobium valency was slightly less than five in these oxynitride perovskites. [ABSTRACT FROM AUTHOR]

Abstract: LaTiO3− x N x films with high nitrogen contents (x ≈0.4–0.8) have been grown on (001)-oriented MgO and LaAlO3 substrates by pulsed reactive crossed-beam laser ablation from a La2Ti2O7 target in a one-step process. These films have a perovskite-type structure, similar to bulk polycrystalline LaTiO2N. The nitrogen content in the films can be changed by selecting the nitriding source, i.e. NH3 or N2 gas pulse, and by varying the substrate temperature. Films deposited on MgO show a preferential (001) and (112) orientation, whereas films on LaAlO3 are predominantly (001) oriented. N(2p) orbitals contribute to the top of the valence band, leading to a considerable decrease in the band gap energy from ∼4.0eV for the parent LaTiO3.5 to ∼2.4–2.9eV for LaTiO3− x N x (x ≈0.4–0.8) films. This results in a strong visible light absorption at wavelengths below ∼500nm. The band gap energies in LaTiO3− x N x films decrease with increasing nitrogen content. The values of the band gap energies for LaTiO3− x N x as a function of the N content agree well with other titanate-based perovskite-type oxynitrides, which confirms the proposed band gap model. [Copyright &y& Elsevier]