• Title/Summary/Keyword: Bi nanoparticles

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Mechanical Properties and Interfacial Reactions of Ru Nanoparticles Added Sn-58Bi Solder Joints (Ru Nanoparticle이 첨가된 Sn-58Bi 솔더의 기계적 신뢰성 및 계면반응에 관한 연구)

  • Kim, Byungwoo;Choi, Hyeokgi;Jeon, Hyewon;Lee, Doyeong;Sohn, Yoonchul
    • Journal of the Microelectronics and Packaging Society
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    • v.28 no.2
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    • pp.95-103
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    • 2021
  • Sn-58Bi-xRu composite solders were prepared by adding Ru nanoparticles to Sn-58Bi, a typical low-temperature solder, and the interfacial reaction and solder joint reliability were analyzed by reacting with Cu/OSP and ENIG surface treated PCB boards. The Cu6Sn5 IMC formed by the reaction with Cu/OSP had little change in thickness depending on the Ru content, and ductile fracture occurred inside the solder during the high-speed shear test without any significant change even after 100 hr aging. In reaction with ENIG, the Ni3Sn4 IMC thickness tended to decrease as the Ru content increased, and ENIG-specific brittle fracture was found in some specimens. Since Ru element is not found near the interface, it is judged not to be significantly involved in the interfacial reaction, and it is analyzed that it mainly exists together with the Bi phase.

REDUCTION OF THERMAL CONDUCTIVITY THROUGH THE DISPERSION OF TiC NANOPARTICLES INTO A P-TYPE Bi0.5Sb1.5Te3 ALLOY BY BALL MILLING AND SPARK PLASMA SINTERING

  • CHEENEPALLI NAGARJUNA;BABU MADAVALI;MYEONG-WON LEE;SUK-MIN YOON;SOON-JIK HONG
    • Archives of Metallurgy and Materials
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    • v.64 no.2
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    • pp.551-557
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    • 2019
  • The dispersion of nanoparticles in the host matrix is a novel approach to enhance the thermoelectric performance. In this work, we incorporate the TiC (x = 0, 1 and 2 wt.%) nanoparticles into a p-type Bi0.5Sb1.5Te3 matrix, and their effects on microstructure and thermoelectric properties were systematically investigated. The existence of TiC contents in a base matrix was confirmed by energy dispersive X-ray spectroscopy analysis. The grain size decreases with increasing the addition of TiC content due to grain boundary hardening where the dispersed nanoparticles acted as pinning points in the entire matrix. The electrical conductivity significantly decreased and the Seebeck coefficient was slightly enhanced, which attributes to the decrease in carrier concentration by the addition of TiC content. Meanwhile, the lowest thermal conductivity of 0.97 W/mK for the 2 wt.% TiC nanocomposite sample, which is ~16% lower than 0 wt.% TiC sample. The maximum figure of merit of 0.90 was obtained at 350 K for the 0 wt.% TiC sample due to high electrical conductivity. Moreover, the Vickers hardness was improved with increase the addition of TiC contents.

Improving the brittle behavior of high-strength shielding concrete blended with lead oxide, bismuth oxide, and tungsten oxide nanoparticles against gamma ray

  • Mohamed Amin;Ahmad A. Hakamy;Abdullah M. Zeyad;Bassam A. Tayeh;Ibrahim Saad Agwa
    • Structural Engineering and Mechanics
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    • v.85 no.1
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    • pp.29-53
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    • 2023
  • High-strength shielding concrete against gamma radiation is a priority for many medical and industrial facilities. This paper aimed to investigate the gamma-ray shielding properties of high-strength hematite concrete mixed with silica fume (SF) with nanoparticles of lead dioxide (PbO2), tungsten oxide (WO3), and bismuth oxide (Bi2O3). The effect of mixing steel fibres with the aforementioned binders was also investigated. The reference mixture was prepared for high-strength concrete (HSCC) containing 100% hematite coarse and fine aggregate. Thirteen mixtures containing 5% SF and nanoparticles of PbO2, WO3, and Bi2O3 (2%, 5%, and 7% of the cement mass, respectively) were prepared. Steel fibres were added at a volume ratio of 0.28% of the volume of concrete with 5% of nanoparticles. The slump test was conducted to workability of fresh concrete Unit weight water permeability, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity tests were conducted to assess concrete's engineering properties at 28 days. Gamma-ray radiation of 137Cs emits photons with an energy of 662 keV, and that of 60Co emits two photons with energies of 1173 and 1332 keV were applied on concrete specimens to assess radiation shielding properties. Nanoparticles partially replacing cement reduced slump in workability of fresh concrete. The compressive strength of mixtures, including nanoparticles was shown to be greater, achieving 94.5 MPa for the mixture consisting of 7.5 PbO2. In contrast, the mixture (5PbO2-F) containing steel fibres achieved the highest values for splitting tensile, flexural strength, and modulus of elasticity (11.71, 15.97, and 42,840 MPa, respectively). High-strength shielded concrete (7.5PbO2) showed the best radiation protection. It also showed the minimum concrete thickness required to prevent the transmission of radiation.

Catalyst Enhanced by Controlling Structure and Shape of Nanocrystals, Support Materials, and Hybrid System in DMFCs (나노입자의 구조와 모양, 담지체 및 하이브리드 시스템 제어를 통한 직접메탄올 연료전지의 촉매 개발)

  • Lee, Young Wook;Shin, Tae Ho
    • Ceramist
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    • v.22 no.2
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    • pp.189-197
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    • 2019
  • Direct methanol fuel cells (DMFCs) have found a wide variety of commercial applications such as portable computer and mobile phone. In a fuel cell, the catalysts have an important role and durability and efficiency are determined by the ability of the catalyst. The activity of the catalyst is determined by the structure and shape control of the nanoparticles and the dispersion of the nanoparticles and application system. The surface energy of nanoparticles determines the activity by shape control and the nanostructure is determined by the ratio of bi- and tri-metals in the alloy and core-shell. The dispersion of nanoparticles depends on the type of support such as carbon, graphen and metal oxide. In addition, a hybrid system using both optical and electrochemical device has been developed recently.

New Synthesis of the Ternary Type Bi2WO6-GO-TiO2 Nanocomposites by the Hydrothermal Method for the Improvement of the Photo-catalytic Effect (개선된 광촉매 효과를 위한 수열법에 의한 삼원계 Bi2WO6-GO-TiO2 나노복합체의 쉬운 합성 방법)

  • Nguyen, Dinh Cung Tien;Cho, Kwang Youn;Oh, Won-Chun
    • Applied Chemistry for Engineering
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    • v.28 no.6
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    • pp.705-713
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    • 2017
  • A novel material, $Bi_2WO_6-GO-TiO_2$ composite, was successfully synthesized using a facile hydrothermal method. During the hydrothermal reaction, the loading of $Bi_2WO_6$ and $TiO_2$ nanoparticles onto graphene sheets was achieved. The obtained $Bi_2WO_{6-GO-TiO2}$ composite photo-catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis-DRS), and X-ray photoelectron spectroscopy (XPS). The $Bi_2WO_6$ nanoparticle showed an irregular dark-square block nanoplate shape, while $TiO_2$ nanoparticles covered the surface of the graphene sheets with a quantum dot size. The degradation of rhodamine B (RhB), methylene blue trihydrate (MB), and reactive black B (RBB) dyes in an aqueous solution with different initial amount of catalysts was observed by UV spectrophotometry after measuring the decrease in the concentration. As a result, the $Bi_2WO_6-GO-TiO_2$ composite showed good decolorization activity with MB solution under visible light. The $Bi_2WO_6-GO-TiO_2$ composite is expected to become a new potential material for decolorization activity. Photocatalytic reactions with different photocatalysts were explained by the Langmuir-Hinshelwood model and a band theory.

Clonazepam Release from Poly(DL-lactide-co-glycolide) Nanoparticles Prepared by Dialysis Method

  • Nah, Jae-Woon;Paek, Yun-Woong;Jeong, Young-Il;Kim, Dong-Woon;Cho, Chong-Su;Kim, Sung-Ho;Kim, Myung-Yul
    • Archives of Pharmacal Research
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    • v.21 no.4
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    • pp.418-422
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    • 1998
  • Aim of this work is to prepare poly(DL-lactide-co-glycolide) (PLGA) nanoparticles by dialysis method without surfactant and to investigate drug loading capacity and drug release. The size of PLGA nanoparticles was 269.9 $\pm$118.7 nm in intensity average and the morphology of PLGA nanoparticies was spherical shape from the observation of SEM and TEM. In the effect of drug loading contents on the particle size distribution, PLGA nanoparticles were monomodal pattern with narrow size distribution in the empty and lower drug loading nanoparticles whereas bi- or trimodal pattern was showed in the higher drug loading ones. Release of clonazepam from PLGA nanoparticles with higher drug loading contents was slower than that with lower loading contents.

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Nanostructured Photoelectrode Materials for Improving Light-Harvesting Properties in DSSCs

  • Jeong, Hyeon-Seok
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2011.05a
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    • pp.7.2-7.2
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    • 2011
  • Photoelectrochemical solar cells such as dye-sensitized cells (DSSCs), which exhibit high performance and are cost-effective, provide an alternative to conventional p-n junction photovoltaic devices. However, the efficiency of such cells plateaus at 11~12%, in contrast to their theoretical value of 33%. The majority of research has focused on improving energy conversion efficiency of DSSC by controlling nanostructure and exploiting new materials in photoelectrode consisting of semiconducting oxide nanoparticles and a transparent conducting oxide electrode (TCO). In this presentation, we introduce monodisperesed TiO2 nanoparticles prepared by forced hydrolysis method and their superiority as photoelectrode materials was characterized with aids of optical and electrochemical analysis. Inverse opal-based scattering layers containing highly crystalline anatase nanoparticles are also introduced and their feasibility for use as bi-functional light scattering layer is discussed in terms of optical reflectance and charge generation properties as a function of optical wavelength.

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Partial Substitution of Copper with Nickel for the Superconducting Bismuth Compound and Its Effect on the Physical and Electrical Properties

  • Kareem Ali Jasim;Riyam Abd Al-Zahra Fadil;Kassim Mahdi Wadi;Auday Hattem Shaban
    • Korean Journal of Materials Research
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    • v.33 no.9
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    • pp.360-366
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    • 2023
  • This study focuses on how the partial substitution of copper by nickel nanoparticles affects the electrical and structural properties of the Bi2Ba2Ca2Cu2.9Ni0.1O10+δ, Bi2Ba2Ca2Cu2.8Ni0.2O10+δ and Bi2Ba2Ca2Cu2.6Ni0.4O10+δ compounds. Approximate values of crystallization size and crystallization percentage for the three compounds were calculated using the Scherer, modified Scherer, and Williamson-Hall methods. A great similarity was observed in the crystal size values from the Scherer method, 243.442 nm, and the Williamson-Hall method, 243.794 nm for the second sample. At the same time this sample exhibited the highest crystal size value for the three methods. In the examination of electrical properties, the sample with 0.1 partial substitution, Bi2Ba2Ca2Cu2.9Ni0.1O10+δ was determined to be the best with a critical temperature of 100 K and an energy gap of 6.57639 × 10-21 MeV. Using the SEM technique to analyze the structural morphology of the three phases, it was discovered that the size of the granular forms exceeds 25 nm. It was determined that the samples' shapes alter when nickel concentration rises. The patterns that reveal the distribution of the crystal structure also exhibit clear homogeneity.