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国外钻井技术 1997年第3期12卷 44-51,F004页

作者： nahm.,JJ 魏作斌

Effect of sintering temperature on microstructure and varistor properties of Zn-V-O-based ceramics incorporated with Mn-Nb-Tb

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Transactions of Nonferrous Metals Society of China 2015年第12期25卷 4040-4045页

作者： C.W.nahm Semiconductor Ceramics Laboratory Department of Electrical Engineering Dongeui University

The effect of sintering temperature on microstructure and varistor properties of Zn-V-O-based ceramics incorporated with Mn-Nb-Tb was investigated. The results showed that the increase of sintering temperature in the range from 875 to 950 °C decreased the densities of sintered pellets in the range of 5.55 to 5.45 g/cm3 and increased the average grain size in the range of 4.1 to 8.8 ？m. The breakdown field decreased noticeably from 7443 to 1064 V/cm with increasing sintering temperature from 875 to 950 °C. The varistor ceramics sintered at 900 ？C exhibited nonlinear properties, with 49.4 in the nonlinear coefficient and 0.21 m A/cm2 in the leakage current density. The dielectric constant increased greatly from 440.1 to 2197.2 with increasing sintering temperature from 875 to 950 °C; however, the dissipation factor exhibited a fluctuation between 0.237 and 0.5. These ceramic compositions and sintering conditions can be applied to the development of advanced multiplayer varistors with silver as an inner electrode.

关键词： Zn-V-O-based ceramics Mn-Nb-Tb sintering varistor properties dielectric characteristics varistor

Effect of small changes in sintering temperature on varistor properties and degradation behavior of V-Mn-Nb-Gd co-doped zinc oxide ceramics

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Transactions of Nonferrous Metals Society of China 2015年第4期25卷 1176-1184页

作者： C.W.nahm Semiconductor Ceramics Laboratory Department of Electrical Engineering Dongeui UniversityBusan 614-714 Korea

The effect of small changes in sintering temperature on microstructure, electrical properties, dielectric characteristics, and degradation behavior of V-Mn-Nb-Gd co-doped zinc oxide ceramics was investigated. With the increase of sintering temperature, the densities of the sintered pellets decreased from 5.54 to 5.42 g/cm3 and the average grain size increased from 4.1 to 11.7 μm. The breakdown field(E1 m A) decreased noticeably from 7138 to 920 V/cm with the increase of sintering temperature. The varistor ceramics sintered at 900 ℃ exhibited excellent nonohmic properties, which were 66 for the nonohmic coefficient and 77 μA/cm2 for the leakage current density. Concerning stability, the varistors sintered at 900 ℃ exhibited the strongest accelerated degradation characteristics, with ΔE1 mA =-9.2% for DC accelerated degradation stress of 0.85 E1 m A at 85 °C for 24 h.

关键词： ZnO-V2O5-based ceramics sintering electrical properties degradation behavior varistor

Graben on the Lunar Nearside: Do Dikes Lie Beneath?

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Acta Geologica Sinica(English Edition) 2016年第S1期90卷 175-176页

作者： Amanda L.nahm German Aerospace Center (DLR)

On the Moon,tectonic structures are concentrated on the nearside,spatially associated with the maria(e.g.,Watters and Johnson,2010),or basalt-filled impact *** graben(or rilles)are long,narrow troughs up to

关键词： Graben on the Lunar Nearside Do Dikes Lie Beneath

Effects of Cr doping on structural and electrochemical properties of Li_(4)Ti_(5)O_(12) nanostructure for sodium-ion battery anode

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Journal of Energy Chemistry 2021年第8期30卷 465-472,I0010页

作者： Sang Hyuk Gong Ji Hyeon Lee Dong Won Chun Jee-Hwan Bae Sung-Chul Kim Seungho Yu Sahn nahm.Hyung-Seok Kim Center for Energy Storage Research Korea Institute of Science and Technology5Hwarang-ro 14-gilSeongbuk-gu02792 SeoulRepublic of Korea Department of Materials Science and Engineering Korea University145Anam-roSeongbuk-gu02841 SeoulRepublic of Korea Department of Chemical and Biological Engineering Korea University145Anam-roSeongbuk-gu02841 SeoulRepublic of Korea Advanced Analysis Center Korea Institute of Science and Technology5Hwarang-ro 14-gilSeongbuk-gu02792 SeoulRepublic of Korea

Sodium-ion batteries are considered as promising alternatives to lithium-ion batteries,owing to their low cost and abundant raw *** the several candidate materials for the anode,spinel-type Li_(4)Ti_(5)O_(12)has potential owing to its superior safety originating from an appropriate operating voltage and the reversible Na^(+)intercalation ***,a low diffusion coefficient for Na^(+)and the insulating nature of LTO remains challenging for practical sodium-ion battery ***,we present a strategy for integrating physical and chemical approaches to achieve superior electrochemical properties in *** demonstrate that carefully controlling the amount of Cr doping is crucial to enhance the electrochemical properties of nanostructured *** Cr doped LTO shows a superior reversible capacity of 110 m Ah g^(-1) after 400 cycles at 1 C,with a three-fold higher capacity(75 m Ah g^(-1))at 10 C compared with undoped LTO *** suggests that appropriately Cr doped nanostructured LTO is a promising anode material for sodium-ion batteries.

关键词： Sodium-ion batteries Spinel type Li_(4)Ti_(5)O_(12) Anode materials Nanostructuring Cr-doping

[001]-texturing of(K,Na)NbO_(3)-based piezoceramics with a pseudocubic structure and their application to piezoelectric devices

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Journal of Materiomics 2024年第3期10卷 632-642页

作者： Su-Hwan Go Seok-Jung Park Seung-Hyun Kim Seok-June Chae Eun-Ji Kim Geun-Su Lee Sahn nahm Department of Materials Science and Engineering Korea UniversitySeoul02841Republic of Korea

0.96(K_(0.5)Na_(0.5-z)Li_(z))(Nb_(0.92)Sb_(0.08))O_(3)-0.04(Ca_(0.5)Sr_(0.5))ZrO_(3)[(KN_(0.5-z)L_(z))NS-CSZ]piezoceramics(0≤z≤0.04)were aligned in the[001]orientation using 3%(in mole)NaNbO_(3)templates with a large Lotgering factor(>97%).Their crystal structures transformed from the orthorhombic-pseudocubic(O-P)structure to the orthorhombic-tetragonal-pseudocubic(O-T-P)structure with an increasing *** P structure was interpreted as a rhombohedral R3m *** piezoelectricity of the compositions increased after[001]-texturing,and the enhancement was proportional to the O phase *** composition(z=0.03)exhibited the highest piezoelectric constant(d_(33);670 pC/N)and electromechanical coupling factor(k_(p);0.56).Piezoelectric energy harvesters were produced using the untextured and textured samples(z=0.03).The textured harvester delivered a large power density of 26.6 mW/mm^(3),which was larger than that of the untextured harvester owing to the enhanced kp and d_(33)×g_(33) of the textured piezoceramic.A multilayer actuator was produced using the textured sample(z=0.03),and it exhibited a large acceleration(44.2 G)and displacement(±3,730 mm)at±25 ***,the[001]-textured(KN_(0.47)L_(0.03))NS-CSZ piezoceramic is suitable for piezoelectric energy harvesters and actuators.

关键词： KNN-Based piezoceramic Lead-free Energy harvester Actuator Reactive template grain growth

Superhydrophobic and antireflective nanograss-coated glass for high performance solar cells

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Nano Research 2014年第5期7卷 670-678页

作者： Hyo Jin Gwon Yensil Park Cheon Woo Moon Sahn nahm.Seok-Jin Yoon Soo Young Kim Ho Won Jang Electronic Materials Research Center Korea Institute of Science and Technology Seou1136-791 Korea Department of Materials Science and Engineering Korea University Seoul 136-701 Korea School of Chemical Engineering and Materials Science Chung-Ang University Seou1156-756 Korea Department of Materials Science and Engineering Research Institute of Advanced Materials Seoul National University Seou1151-744Korea

We present a facile method for producing superhydrophobic nanograss-coated （SNGC） glass surfaces that possess both reduced reflectivity and self-cleaning properties at the air/glass interface. The refractive index of a CaF2 nanograss （NG） layer on a glass substrate, deposited by glancing angle vapor deposition, is 1.04 at 500 nm, which is the second-lowest value ever reported so far. The fluorinated NG layer gives rise to a high water contact angle （〉150°） and very efficient cleaning out of dust with water drops. Using the dual functionalities of the SNGC glass, we demonstrate superhydrophobic and antireflective organic photovoltaic cells with excellent power conversion efficiency.

关键词： superhydrophobic antireflective self-cleaning nanograss solar cells glancing angle deposition

Cerberus Fossae, Mars: The Case for Dike Intrusion-related Formation and Modification

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Acta Geologica Sinica(English Edition) 2016年第S1期90卷 173-174页

作者： Amanda L.nahm.Matthew W.PENDLETON Simon A.KATTENHORN German Aerospace Center (DLR) University of Idaho Earth Consultants International University of Alaska Anchorage

Cerberus Fossae(CF)is a large fracture system on Mars that extends for more than 1200 *** structures,or fossae,are southeast of,and oriented approximately radially to,the large shield volcano Elysium ***

关键词： Burr Cerberus Fossae Mars CF

Ceramic-metal package for high power LED lighting

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Frontiers of Optoelectronics 2012年第2期5卷 133-137页

作者： Yu Jin HEO Hyo Tae KIM Sahn nahm.Jihoon KIM Young Joon YOON Jonghee KIM Korea Institute of Ceramic Engineering and Technology Seoul 153-801 Korea Department of Materials Science and Engineering Korea University Seoul 136 701 Korea

High power light-emitting diodes （LEDs） lighting has drawn a great interest in the field of street light system in recent years. Key parameters for successful launching of LED street light in the commercial market are price and light efficiency, respectively, and they are greatly influenced by the materials and design factors used in high power LED package. This article presents a new design and materials processing technology to realize the solution of LED packaging with advantageous in price and performance. Cost effective materials and processing technology can be realized via thick film glass-ceramic insulating layer and silver conductor. Highly effective thermal design using direct heat dissipation to heat sink in LED package is demonstrated.

关键词： light-emitting diodes (LEDs) package high-power thick film heat dissipation thermal resistance

Very High Cycle Fatigue Behaviors and Surface Crack Growth Mechanism of Hydrogen-Embrittled AISI 304 Stainless Steels

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Materials Sciences and Applications 2018年第4期9卷 393-411页

作者： Seung-Hoon nahm.Hyun-Bo Shim Un-Bong Baek Chang-Min Suh Korea Research Institute of Standards and Science Daejeon Republic of Korea School of Mechanical Engineering Yeungnam University Daegu Republic of Korea School of Mechanical Engineering Kyungpook Nat’l University Daegu Republic of Korea

The influence of hydrogen embrittlement on the fatigue behaviors of AISI 304 stainless steel is investigated. The fatigue endurance limits of the untreated and hydrogen-embrittled materials were almost the same at 400 MPa, and hydrogen embrittlement had little influence even though the sample contained about 8.1 times more hydrogen. Thus, the sensitivity of hydrogen gas in this material is very low. A surface crack initiation, growth, coalescence, and micro ridge model is proposed in this study. Slip line formation?⇒microcrack formation?⇒increases in the crack width, and blunting of the crack tip as it grows?⇒formation of many slip lines because of deformation in the shear direction?⇒growth of the crack in the shear direction, forming micro ridges, coalescence with adjacent cracks ⇒?continuous initiation, growth, coalescence, and ridge formation of surface cracks and specimen breakage.

关键词： Hydrogen-Embrittled Fatigue Behaviors Surface Crack Initiation Growth Coalescence Micro Ridge Formation VHCF (Very High Cycle Fatigue) Fracture Surface Analysis