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排序方式: 共有379条查询结果,搜索用时 15 毫秒
21.
Trinh Nguyen Thi Phuoc Cao Van Duc Duong Viet Viet Dong Quoc Hayeong Ahn Viet Anh Cao Min-Gu Kang Junghyo Nah Byong-Guk Park Jong-Ryul Jeong 《Ceramics International》2021,47(12):16770-16775
In this study, we examined the dependence of surface morphology and spin Seebeck effect (SSE) voltages on the poly[vinylpyrrolidone] (PVP) concentration in polycrystalline Y3Fe5O12 (YIG) ultrathin films on a silicon substrate synthesized by metal-organic decomposition followed by a crystallization process. During fabrication, PVP concentrations of 0.5–2 g were used while all other conditions remained fixed. Atomic force microscopy and grazing incidence X-ray diffraction (XRD) measurements revealed a strong dependence of crystallinity and sample morphology on PVP concentration. The 1-g PVP sample had the smoothest surface, with a root mean square roughness of 0.2 nm, as well as superior bulk uniformity with respect to the shape and intensity of XRD reflection peaks. This was confirmed by scanning electron microscopy measurements of a cross-section of the sample that revealed a uniform film without pores. SSE measurements were performed to obtain the output SSE voltages (VSSE) of all samples, to which a platinum layer was added as a spin-detection layer. Repeatedly, the 1-g PVP sample had the best performance, demonstrating the importance of film crystallinity and morphology in the spin-to-charge conversion efficiency of YIG films. 相似文献
22.
In the present study, white light emission based on both upconversion and thermal processes from single-phase yttrium silicate nanopowder doped with Neodymium (III) (Nd3+) was investigated at both room pressure and vacuum (0.01 mbar) with a diode laser excitation of 808 nm. 1% Nd3+ doped (per mole) yttrium silicate (Y2O3:SiO2) nanopowder was synthesized by using the sol-gel method and annealed at 1250 °C for 12 h to obtain the powder form. Emission for upconverted white light mainly due to the transitions of Nd3+ ions was obtained below ~ 5.79 W of the laser beam power at atmospheric pressure. For powers exceeding ~ 5.79 W, the powder emitted a thermal white light (WL) due to the photon avalanche mechanism together with thermal processes. The threshold power to obtain thermal white light with the transitions of Nd3+ ions was decreased to ~ 3.51 W at the vacuum condition. These processes were investigated in detail by studying the spectral differences of the rise and decay patterns at atmospheric pressure and vacuum conditions. 相似文献
23.
Thin films of Y2O3 : Eu cathodoluminescent (CL) phosphors were deposited using pulsed laser deposition using deposition temperature between 250°C and 800°C, O2 pressures between residual vacuum (2×10−5 Torr) and 6 Torr, and post annealing up to 1200° for 1 h in air. The CL efficiency of the best thin film was about one third that of the starting powder. The brightness and efficiency of the thin films improved as the deposition temperature, O2 pressure and post annealing temperature were increased, except that O2 pressures above 600 mTorr did not significantly improve the CL properties. At deposition temperatures >600°C, the surface morphology changed from a smooth film to a nodular deposit for O2 pressures >200 mTorr, with nodule dimensions ≈100 nm. Simultaneously, the CL properties improved dramatically because of enhanced optical scattering out of the thin film. Optical scattering was discussed in terms of anomalous diffraction. The CL properties also improved dramatically with high temperature post annealing. This effect was interpreted in terms of improved crystallinity and activation of the Eu. The low brightness and efficiency of thin films versus powder was affected by depletion of the Eu in the thin films owing to the deposition process. 相似文献
24.
E. Caudron H. Buscail R. Cueff Y. P. Jacob M. F. Stroosnijder 《Thin solid films》1999,350(1-2):168-172
Low manganese steel samples were yttrium implanted using ion implantation technique. Sample compositions and structures were investigated before and after yttrium implantations to determine the yttrium distribution in low manganese steel. Yttrium implantation depth profiles were characterized using conventional techniques such as X-ray photoelectron spectroscopy (XPS), reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), glancing angle X-ray diffraction (GAXRD) and a nuclear analytical method: Rutherford backscattering spectroscopy (RBS). The aim of this study is to show that correlation between composition and structural analyses allows to understand the effect of implanting yttrium in low manganese steel. 相似文献
25.
Yu Hua Wang Tadashi Endo Xuan Guo Yukio Murakami Mizumoto Ushirozawa 《Journal of the Society for Information Display》2004,12(4):495-499
Abstract— The broad bands at around 155 nm for GdAl3(BO3)4:Eu, at 184 nm for Ca4GdO(BO3)3:Eu, at 183 nm for Gd2SiO5:Eu, and at 170 nm for GdAlO3:Eu were observed. These bands were assigned to the charge‐transfer (CT) transition of Gd3+‐O2?. In the excitation spectrum of (Gd,Y)BO3:Eu, a broadened excitation band was observed in VUV region. It could be considered that this band was composed of two bands at about 160 and 166 nm. The preceding band was assigned to the BO3 group absorption. The later one at about 166 nm could be assigned to the CT transition of Gd3+‐O2?, according to the result of GdAl3(BO3)4:Eu, Ca4GdO(BO3)3:Eu, Gd2SiO5:Eu, and GdAlO3:Eu. The excitation spectra overlapped between the CT transition of Gd3+‐O2? and BO3 groups absorption. It caused the emission of Eu3+ to take place effectively in the trivalent europium‐doped (Gd,Y)BO3 host lattice under 147‐nm excitation. 相似文献
26.
Influence of yttrium as a minority alloying element on the corrosion behavior in Fe-based bulk metallic glasses 总被引:1,自引:0,他引:1
The role of yttrium in corrosion behavior in an HCl solution was studied systematically by comparing bulk FeCrMoCB metallic glasses with and without yttrium. The corrosion resistance was very sensitive to minor yttrium addition. The material exhibits a detrimental effect on corrosion resistance at 0.5 at.% yttrium addition while a beneficial effect at more yttrium additions. Such effects are argued to be associated with variations of the semiconductor properties of passive film (i.e. defects concentration and band structure of passive film), induced by minority yttrium alloying element doping. It was shown that there exhibits a bi-layer structure of passive film on Fe-based metallic glasses. The outer layer with high valence cations is responsible for the dissolution behavior of the passive film, whereas the inner layer with doped oxides connects with the semiconductor properties. This result presents us an important hint that the corrosion resistance of metallic glasses can be improved by elaborately tailoring the defect structure of passive film via proper additions of minor alloying elements. 相似文献
27.
《Ceramics International》2023,49(7):10375-10383
Zirconia powder with good dispersion, fine particle size, and stability is used as high-quality raw material in many fields, such as ceramic materials and refractories. In this paper, the influence of lanthanum oxide (La2O3) and yttrium oxide (Y2O3) co-doped zirconia (ZrO2) on its phase transformation behavior, phase stability, and microstructure were investigated. The ball milling method is applied to fabricate different amounts of La2O3-doped yttrium oxide stabilized zirconia oxide. Then, the powder obtained from ball milling was roasted using the microwave sintering method. The samples were characterized using XRD, FT-IR, Raman, SEM and BET to determine the optimal conditions for La2O3–Y2O3 co-doped ZrO2 powder. The results showed that replacing part of Y2O3 with La2O3 increases zirconia powder's tetragonal and cubic phase, enhancing the fracture strength of the subsequent synthesized materials. At the same time, the stability of zirconia stabilized with La2O3 doping is significantly improved compared to that of Y2O3 alone. According to all analysis methods, when the doping amount is 2.8Y0.2La, the powder's phase composition, stability, particle size distribution, and dispersion degree are the best compared with other doping amounts in our study. The obtained powder has a smaller specific surface area, a lower surface energy, a smaller porosity, and a higher density. The samples under this condition can be better used in subsequent materials. The enhancement of various properties of zirconia can significantly prolong the service life of materials in practical applications. 相似文献
28.
Rareearthsandtheiralloysarewidelyusedinmagnetic,opticalandelectricmaterials.Butitisdifficulttoelectrodepositerareearthsandtheirall0ysinaqueouss0lutionsduetotheactiv-ityofrareearths.Thetemperatureofmoltensaltssystemwouldhehigh.Iftherareearthsandtheiralloyscanhepreparedinorganicsolventatroomtemperaturebyelectrodeposition,itwillgreatlyenhancetheirapplicationrangesasfunc-tional.at.ri.l.[l~4j.Inthepaper,thec0nduc-tivityofYCla-liCl0`-DMS0systemwasmea-sured,andtheelectrochemicalbehavi0rofY3 wasinv… 相似文献
29.
《Journal of Industrial and Engineering Chemistry》2014,20(2):505-511
Yttrium-stabilized zirconia nanotubes (YSZNTs) were prepared using a conventional hydrothermal method, and their characteristics were compared with those of yttrium-stabilized zirconia nanoparticles (YSZNPs) synthesized in this study and with those of commercial YSZNPs (CYSZNPs). YSZNTs had widths and lengths of 20–30 nm and 100–700 nm respectively. The electrical conductivity of NiO (60.0 wt%)-loaded YSZNTs (40.0 wt%) was higher than those of NiO/YSZNPs and NiO/CYSZNPs at the same NiO loading. The zeta-potentials of YSZNTs in aqueous solution, determined by electrophoretic light scattering (ELS), indicated high positive surface charges at lower pH values, which is known to be related to surface stability, but negative values at high pH. The results of cyclic voltammetry (CV) and H2-temperature-programmed reduction (H2-TPR) confirmed that NiO(60.0 wt%)/YSZNTs (Ered = −0.445 mV) were more reduced than NiO/YSZNPs (Ered = −0.517 mV) and NiO/CYSZNPs (Ered = −0.516 mV). 相似文献
30.
高能氩离子在钇铁石榴石中引起的非晶化研究 总被引:1,自引:0,他引:1
用倾斜样品X射线学和饱和磁化强度测量,研究了960MeV氩离子在多晶钇铁石榴(YIG)Y3Fe5O12中引起的非晶化过程。分析结果表明,960Me氩离子辐照引起YIG晶态→非昌态转变是一个逐渐的过程,在这个过程中电子能损起主导作用但也需要一定的辐照剂量。 相似文献