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121.
Junpeng Xue Zhongkai Yu Hyeon Mi Noh Jung Hyun Jeong Byung Chun Choi Sung Heum Park Bo Ram Lee Peng Du Mingjun Song 《Journal of the American Ceramic Society》2021,104(10):5086-5098
Ce3+/Tb3+ co-doped NaMgBO3 phosphors were successfully synthesized by solid-state method. Under 381 nm excitation, the cyan emission owing to the 5d → 4f of Ce3+ ions and green emissions arising from the 5D4 → 7FJ (J = 6, 5, 4, and 3) transitions of Tb3+ ions were seen in all the phosphors. Through theoretical analysis, one knows that the energy transfer from Ce3+ to Tb3+ ions with high efficiency of 83.74% was contributed by dipole–dipole transition. Furthermore, the internal quantum efficiency of NaMgBO3:0.01Ce3+,0.03Tb3+ phosphor was 54.28%. Compared with that of at 303 K, the emission intensity of the developed products at 423 K still kept 73%, revealing the splendid thermal stability of the studied phosphors. Through utilizing the resultant phosphors as cyan-green components, the fabricated white-LED device exhibited an excellent correlated color temperature of 2785 K, high color-rendering index of 85.73, suitable luminance efficiency of 25.00 lm/W, and appropriate color coordinate of (0.4279, 0.3617). Aside from the superior photoluminescence, the synthesized phosphors also exhibited excellent cathode-luminescence properties which were sensitive to the current and accelerating voltage. Furthermore, the NaMgBO3:0.01Ce3+,0.03Tb3+ phosphors with multi-mode emissions were promising candidates for optical anti-counterfeiting. All the results indicated that the Ce3+/Tb3+ co-doped NaMgBO3 phosphors were potential multi-platforms toward white-LED, field emission displays, and optical anti-counterfeiting applications. 相似文献
122.
Seong-Joong Kim Yeojin Ahn Jeong F. Kim Seung-Eun Nam Hosik Park Young Hoon Cho Kyung-youl Baek You-In Park 《应用聚合物科学杂志》2021,138(7):49860
To overcome the plasticization effect in polyimide membranes, many researchers have proposed crosslinking method. This can reduce an inter-segmental mobility by tightening and rigidifying the polymer chains. However, it is difficult to modify the whole polymer chains throughout the membrane because the reaction can be hindered by the diffusion rate of the crosslinker. In particular, it is hard for bulky crosslinker to penetrate a dense membrane with a small d-spacing. This study investigated the effect of crosslinking a dense Matrimid membrane with p-phenylenediamine (p-PDA) via two different crosslinking methods (i.e., methanol-swelling crosslinking process [M-SCP] and liquid-phase crosslinking process [L-PCP]). Most of the crosslinking reaction in M-SCP occurs on the membrane surface due to difficulty in penetration of the bulky p-PDA into the Matrimid dense membrane. In contrast, the L-PCP allows uniform crosslinking across the membrane. The membranes crosslinked using L-PCP showed excellent chemical resistance. Furthermore, the plasticization phenomenon was not observed in the membranes crosslinked using L-PCP with p-PDA more than 15%. Meanwhile, the membrane crosslinked using M-SCP exhibited poor plasticization and chemical resistance properties. These results showed that the L-PCP method can be more effective for the crosslinking of dense membrane to deliver both high plasticization and chemical resistance. 相似文献
123.
Superplastic deformation and crystallization behavior of a Cu54Ni6Zr22Ti18 metallic glass were investigated. A maximum elongation of 650% was obtained at 733 K at 1 × 10−2 s−1 from the sheet fabricated by squeeze copper-mold casting method. At low strain rates, the strain-rate-sensitivity exponent value was close to 1, suggesting that Newtonian-like behavior governed the plastic flow. At a high strain rate around 10−2 s−1, a transition from Newtonian to non-Newtonian behavior took place with decrease in m value. Large strain hardening by crystallization occurred during the course of deformation. The strain hardening was found to be caused by crystallization according to the analyses of the relation of true stress vs. testing time, T-T-T diagram and DSC characteristics. The time periods up to the strain before strain hardening at 733 K for the Cu54Ni6Zr22Ti18 metallic glass were similar to that of the Zr65Al10Ni10Cu15 metallic glass at 696 K as 180–300 s (3–5 min). This coincidence could be explained by comparison of their T-T-T diagrams showing that the incubation times for crystallization of the Cu BMG at 733 K and for Zr BMG at 696 K are similar. 相似文献
124.
In the present study, the densification of Ti/TiB composites, the growth behavior ofin-situ formed TiB reinforcement, the effects of processing variables — such as reactant powder (TiB2, B4C), sintering temperature and time — on the microstructures and the mechanical properties ofin-situ processed Ti/TiB composites have been investigated. Mixtures of TiB2 or B4C powder with pure titanium powder were compacted and presintered at 700°C for 1 hr followed by sintering at 900, 1000, 1100,
1200, and 1300°C, respectively, for 3hrs. Some specimens were sintered at 1000°C for various times in order to study the formation
behavior of TiB reinforcementin-situ formed within the pure Ti matrix. TiB reinforcements were formed through different mechanisms, such as the formation of fine
TiB and the formation of coarse TiB by Ostwald ripening or the coalescence of fine TiB. There was no crystallographic relationship
between TiB reinforcement and the matrix. There were voids at the interface between the TiB reinforcement and the Ti matrix
due to the preferential growth of coarse TiB without a particular crystallographic relationship with pure Ti matrix and the
surface energy between the Ti matrix and TiB reinforcements. Therefore, the densification of Ti/TiB2 compacts was hindered by the preferential growth of coarse TiB reinforcements. The mechanical properties ofin-situ processed composites were evaluated by measuring the compressive yield strength at ambient and high temperatures. The compressive
yield strength of thein situ processed composites was higher than that of the Ti-6A1-4V alloy. It was also found that the compressive yield strength of
the composite made from TiB2 reactant powder was higher than that of the composite made from B4C at the same volume fraction of reinforcement. A crack path examination suggested that the bonding nature of interface between
matrix and reinforcement made from TiB2 reactant powder was better than that made from B4C. 相似文献
125.
Sun-Chan Jeong Ichiro Katayama Hirokane Kawakami Yutaka Watanabe Hironobu Ishiyama Nobuaki Imai Yoshikazu Hirayama Hiroari Miyatake Masao Sataka Satoru Okayasu Hiroyuki Sugai Shin-Ichi Ichikawa Katsuhisa Nishio Shinichi Mitsuoka Takamitsu Nakanoya Masahito Yahagi Takanori Hashimoto Kazunori Takada Mamoru Watanabe Tomoko Ishikawa Akihiro Iwase 《Journal of Phase Equilibria and Diffusion》2005,26(5):472-476
For the effective use of short-lived radioactive beams, soon to be available at the Tokai Radioactive Ion Accelerator Complex, the authors have developed a radiotracer method for diffusion studies in solids. The experimental test was performed by the measurement of the diffusion coefficients of Li in a sample of the compound βLiAl using an α-emitting radiotracer of 8Li (T1/2=0.84 s). It was found that the time-dependent yields of the α particles from the diffusing 8Li that was initially implanted in the sample could be used as a measure of the diffusivity of the tracer in a nondestructive way. The method was applied to measure the self-diffusion coefficients of Li in βLiGa, and for investigating how the Li diffusion in the Li ionic conductors is affected by the concentration of atomic defects (i.e., the existence of the atomic vacancies of Li and the defects in Ga sites that are replaced by Li). 相似文献
126.
In the conventional metallothermic reduction (MR) process used to obtain tantalum powder in batch-type operation, it is difficult
to control the morphology and location of the tantalum deposits. In contrast, an electronically mediated reaction (EMR) process
is capable of overcoming this difficulty. It has the advantage of being a continuous process, but has the disadvantage of
a poor reduction yield. A process known as the MR-EMR combination process is able to overcome the shortcomings of the MR and
EMR processes. In this study, an MR-EMR combination process is applied to the production of tantalum powder via sodium reduction
of K2TaF7. In the MR-EMR combination process, the total charge passed through an external circuit and the average particle size (FSSS)
increase as the reduction temperature increases. In addition, the proportion of fine particles (−325 mesh) decreases as the
reduction temperature increasess. The tantalum yield improved from 65 to 74% as the reduction temperature increased. Taking
into account the charge, impurities, morphology, particle size and yield, a reduction temperature of 1123 K was found to be
optimum for the MR-EMR combination process. 相似文献
127.
Jae Woong Choi Gil Ho Hwang Won Kyu Han Sung Goon Kang 《Metals and Materials International》2006,12(1):75-80
Ni−B film of 1 μm thickness was electrolessly deposited on an electroplated Cu bus electrode. The film, which encapsulates
the Cu bus electrodes, prevents Cu oxidation and serves as a diffusion barrier against Cu contamination of the transparent
dielectric layer in a plasma display during the firing process at 580 °C. The microstructure of theas-deposited barrier film was amorphous phase and crystallized to Ni and Ni3B after annealing at 300 °C. The good barrier properties observed here can be explained by Ni3B precipitates at the grain boundaries acting as a fast diffusion path via pre-annealing at 300 °C before the firing process
at 580 °C. 相似文献
128.
A timing controller embedded driver IC with 3.24‐Gbps eDP interface for chip‐on‐glass TFT‐LCD applications 下载免费PDF全文
Tae‐Jin Kim Changhoon Baek Sengsub Chun Kil‐Hoon Lee Jong‐Il Hwang Kyeonghwan Kwon Yong‐Hun Kim Hyun‐Sang Park Youngmin Shin Seong‐young Ryu Jae‐Youl Lee Gyoocheol Hwang Gyeongnam Kim 《Journal of the Society for Information Display》2016,24(5):299-306
This paper presents a timing controller embedded driver (TED) IC with 3.24‐Gbps embedded display port (eDP), which is implemented using a 45‐nm high‐voltage CMOS process for the chip‐on‐glass (COG) TFT‐LCD applications. The proposed TED‐IC employs the input offset calibration scheme, the zero‐adjustable equalizer, and the phase locked loop‐based bang‐bang clock and data recovery to enhance the maximum data rate. Also, the proposed TED‐IC provides efficient power management by supporting advanced link power management feature of eDP standard v1.4. Additionally, the smart charge sharing is proposed to reduce the dynamic power consumption of output buffers. Measured result demonstrates the maximum data rate of 3.24 Gbps from a 1.1 V supply voltage with a 7.9‐inch QXGA 60‐Hz COG‐LCD prototype panel and 44% power saving from the display system. 相似文献
129.
Gait Generation and Stabilization for Nearly Passive Dynamic Walking Using Auto‐distributed Impulses 下载免费PDF全文
We propose a state feedback control design via linearization for flexible walking on flat ground. First, we generate nearly passive limit cycles, being stable or not, using impulsive toe‐off actuations. The term ‘nearly passive’ means that the dynamics is completely passive almost everywhere except at the toe‐off moment. A feature of our gait generation method is that walking gaits are characterized only by amounts of supplied energy, and we observe that other variables, including input torques, are auto‐balanced via our method. After gait generation, we design a feedback controller considering robustness and input saturation. As a result, each limit cycle can be matched with its respective controller classified only by energy levels. We have verified that walking speeds monotonically increase by adding more energy, and the ankle joint plays a significant role in compass‐gait walking. Finally, instead of applying impulsive torques, we discuss a practical issue regarding realistic control inputs that ensure stable gait transitions as energy levels are elevated. 相似文献
130.
We study quantum teleportation between two different types of optical qubits using hybrid entanglement as a quantum channel under decoherence effects. One type of qubit employs the vacuum and single-photon states for the basis, called a single-rail single-photon qubit, and the other utilizes coherent states of opposite phases. We find that teleportation from a single-rail single-photon qubit to a coherent-state qubit is better than the opposite direction in terms of fidelity and success probability. We compare our results with those using a different type of hybrid entanglement between a polarized single-photon qubit and a coherent state. 相似文献