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71.
F. Stokker-Cheregi M. Zamfirescu A. Vinattieri M. Gurioli I. Sellers F. Semond M. Leroux J. Massies 《Superlattices and Microstructures》2007,41(5-6):376
We discuss the thermalization of the polariton population from a bulk GaN λ/2 microcavity at room temperature. Simultaneous optical measurements of reflectivity and photoluminescence (PL), as well as time resolved measurements, reveal strong light–matter coupling. Transfer matrix theory is used to calculate reflectivity, absorption, and transmission coefficients for the structure. The PL emission is found to be thermalized, despite its very short lifetime, suggesting the existence of very fast energy relaxation channels. 相似文献
72.
Deuterium and nitrogen depth profiles in Ti with modified surfaces have been measured with Auger electron spectroscopy, secondary ion mass spectroscopy, and D(3He,p)4He nuclear reaction analysis. Nitrogen-rich surfaces layers of varying thicknesses were created on Ti by exposure to N2 gas at 650°C. Deuterium loading was performed by exposure to 1 Torr of D2 gas at 500°C. The deuterium distribution was influenced by nitrogen in the near-surface regions of all samples. Specifically, deuterium solubility was suppressed in surface regions of high (greater than 1%) nitrogen concentration. The deuterium solubility also remained low within the first few microns, well beyond the region of high nitrogen concentration. This effect is attributed to internal elastic stresses imposed by the non-deuterium absorbing nitrogen-rich layer on the Ti. These stresses prohibit the volume expansion associated with deuterium absorption. We estimate stresses on the order of 3–4 GPa are required to suppress the deuterium solubility to the values observed. The deuterium absorption kinetics were observed to depend systematically on the thickness of the nitrogen-rich layer. This is consistent with limited solubility near the surface or a surface poisoning effect influencing the overall deuterium diffusion from the gas phase into the Ti bulk. 相似文献
73.
74.
Chun Shan LU Xiao Nian LI* Yi Feng ZHU Hua Zhang LIU Chun Hui ZHOU Zhejiang Key Laboratory of Heterogeneous Catalysis Catalysis Institute of Zhejiang University of Technology Hangzhou 《中国化学快报》2004,(1)
Transition metal nitrides belong to a class of interstitial compounds, in which nitrogen atoms replace oxygen. They possess some technologically useful properties as packaging materials, structural materials and catalytic materials. Since Boudart1 succeeded to prepare high specific surface area g-Mo2N in 1985 using the NH3 temperatureprogrammed reduction method, transition metal nitrides have attracted much attention as potential catalysts owing to their similarity with the group VIII met… 相似文献
75.
Q. Sun J.C. Zhang J. Chen H. Wang Y.T. Wang H. Yang L.P. Guo 《Applied Surface Science》2006,252(8):3043-3050
Both cracked and crack-free GaN/Al0.55Ga0.45N multiple quantum wells (MQWs) grown on GaN template by metalorganic chemical vapor deposition have been studied by triple-axis X-ray diffraction, grazing-incidence X-ray reflectivity, atomic force microscope, photoluminescence spectroscopy and low-energy positron annihilation spectroscopy. The experimental results show that cracks generation not only deteriorates the surface morphology, but also leads to a period dispersion and roughens the interfaces of MQWs. The mean density of dislocations in MQWs, determined from the average full-width at half-maximum of ω-scan of each satellite peak, has been significantly enhanced by the cracks generation. Furthermore, the measurement of annihilation-line Doppler broadening reveals a higher concentration of negatively charged vacancies in the cracked MQWs. The combination of these vacancies and the high density of edge dislocations are assumed to contribute to the highly enhanced yellow luminescence in the cracked sample. 相似文献
76.
The possibility of forming niobium oxynitride through the nitridation of niobium oxide films in molecular nitrogen by rapid
thermal processing (RTP) was investigated. Niobium films 200 and 500 nm thick were deposited via sputtering onto Si(100) wafers
covered with a thermally grown SiO2 layer 100 nm thick. These as-deposited films exhibited distinct texture effects. They were processed in two steps using an
RTP system. The as-deposited niobium films were first oxidized under an oxygen atmosphere at 450 °C for various periods of
time and subsequently nitridated under a nitrogen atmosphere at temperatures ranging from 600 to 1000 °C for 1 min. Investigations
of the oxidized films showed that samples where the start of niobium pentoxide formation was detected at the surface and the
film bulk still consisted of a substoichiometric NbOx phase exhibited distinctly lower surface roughness and microcrack densities than samples where complete oxidation of the
film to Nb2O5 had occurred. The niobium oxide phases formed at the Nb/substrate interface also showed distinct texture. Zones of niobium
oxide phases like NbO and NbO2, which did not exist in the initial oxidized films, were formed during the nitridation. This is attributed to a “snow-plough
effect” produced by the diffusion of nitrogen into the film, which pushes the oxygen deeper into the film bulk. These oxide
phases, in particular the NbO2 zone, act as barriers to the in-diffusion of nitrogen and also inhibit the outdiffusion of oxygen from the SiO2 substrate layer. Nitridation of the partially oxidized niobium films in molecular nitrogen leads to the formation of various
niobium oxide and nitride phases, but no indication of niobium oxynitride formation was found.
Figure Schematic representation of the phase distribution in 200 nm Nb film on SiO2/Si substrate after two steps annealing using an RTP system. The plot below represents the SIMS depth profiles of the nitridated
sample with the phase assignment 相似文献
77.
Sophia L. Wandelt Dr. Alexander Mutschke Dr. Dmitry Khalyavin Robert Calaminus Jennifer Steinadler Prof. Dr. Bettina V. Lotsch Prof. Dr. Wolfgang Schnick 《Angewandte Chemie (International ed. in English)》2023,62(50):e202313564
Multianionic metal hydrides, which exhibit a wide variety of physical properties and complex structures, have recently attracted growing interest. Here we present Sr6N[BN2]2H3, prepared in a solid-state ampoule reaction at 800 °C, as the first combination of nitridoborate, nitride and hydride anions within a single compound. The crystal structure was solved from single-crystal X-ray and neutron powder diffraction data in space group P21/c (no. 14), revealing a three-dimensional network of undulated layers of nitridoborate units, strontium atoms and hydride together with nitride anions. Magic angle spinning (MAS) NMR and vibrational spectroscopy in combination with quantum chemical calculations further confirm the structure model. Electrochemical measurements suggest the existence of hydride ion conductivity, allowing the hydrides to migrate along the layers. 相似文献
78.
Dongdong Chu Yi Huang Congwei Xie Evgenii Tikhonov Ivan Kruglov Guangmao Li Shilie Pan Zhihua Yang 《Angewandte Chemie (International ed. in English)》2023,62(16):e202300581
Traditional infrared (IR) nonlinear optical (NLO) materials such as AgGaS2 are crucial to key devices for solid-state lasers, however, low laser damage thresholds intrinsically hinder their practical application. Here, a robust strategy is proposed for unbiased high-throughput screening of more than 140 000 materials to explore novel IR NLO materials with high thermal conductivity and wide band gap which are crucial to intrinsic laser damage threshold. Via our strategy, 106 compounds with desired band gaps, NLO coefficients and thermal conductivity are screened out, including 8 nitrides, 68 chalcogenides, in which Sr2SnS4 is synthesized to verify the reliability of our process. Remarkably, thermal conductivity of nitrides is much higher than that of chalcogenides, e.g., 5×AgGaS2 (5.13 W/m K) for ZrZnN2, indicating that nitrides could be a long-neglected system for IR NLO materials. This strategy provides a powerful tool for searching NLO compounds with high thermal conductivity. 相似文献
79.
Synthesis of Cadmium Nitride Cd3N2 by Thermolysis of Cadmium Azide Cd(N3)2 and Crystal Structure Determination from X‐ray Powder Diffraction Data Cadmium nitride Cd3N2 was obtained by thermolysis of cadmium azide Cd(N3)2 at 2·10?6 mbar and 210 °C. It was obtained as a black, crystalline powder which becomes brown in air due to formation of cadmium amide Cd(NH2)2. The crystal structure of Cd3N2 was determined from X‐ray powder diffraction data and refined by the Rietveld method ( , a = 10.829(9) Å, V = 1270(3) Å3, Z = 16, R(F2) = 0.1196). Cd3N2 crystallizes in the anti‐bixbyite structure type and is isotypic to Ca3N2. 相似文献
80.
Donghai Wu Zhichuan Niu Shiyong Zhang Haiqiao Ni Zhenhong He Zheng Sun Qin Han Ronghan Wu 《Journal of Crystal Growth》2006,290(2):494-497
Sb-assisted GaInNAs/GaAs quantum wells (QWs) with high (42.5%) indium content were investigated systematically. Transmission electron microscopy, reflection high-energy electron diffraction and photoluminescence (PL) measurements reveal that Sb acts as a surfactant to suppress three-dimensional growth. The improvement in the 1.55 μm range is much more apparent than that in the 1.3 μm range, which can be attributed to the difference in N composition. The PL intensity and the full-width at half maximum of the 1.55 μm single-QW were comparable with that of the 1.3 μm QWs. 相似文献