Improved transport critical current properties in glycerin-doped MgB₂ wire using milled boron powder and a solid-state reaction of 600 °C

Jun, Byung-Hyuk,Kim, Jung Ho,Kim, Chan-Joong,Choo, Kee Nam Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.650 No.-

<P><B>Abstract</B></P> <P>We adopted simultaneously three effects of milling, carbon (C) doping and solid-state reaction to improve critical current properties of MgB<SUB>2</SUB> superconducting wire. The influences of heat-treatment temperature, including a conventional solid–liquid reaction of 650–1000 °C and a solid-state reaction of 600 °C below the melting point (650 °C) of Mg powder, were examined on the transport superconducting properties of <I>in situ</I> powder-in-tube (PIT) processed MgB<SUB>2</SUB>/Fe wires using ball-milled and glycerin-treated boron (B) powder. The aims of the mechanical milling and liquid glycerin treatment of the B powder were to reduce the grain size of the MgB<SUB>2</SUB> and achieve homogeneous C incorporation into the MgB<SUB>2</SUB>, respectively. The superconducting properties of MgB<SUB>2</SUB> wires heat-treated in the range of 650–1000 °C were investigated, and it was also investigated as to whether the C incorporation occurred even in a low-temperature solid-state process of 600 °C, thus resulting in an improvement of the superconducting properties by obtaining both high grain boundary density and C substitution effects. The MgB<SUB>2</SUB> phase formation, actual C substitution amount, full width at half maximum (FWHM), critical temperature (<I>T</I> <SUB>c</SUB>), magnetic field dependence of transport critical current density (<I>J</I> <SUB>c</SUB>) and temperature dependence of the upper critical field (<I>H</I> <SUB>c2</SUB>) were evaluated for glycerin-doped MgB<SUB>2</SUB>/Fe wires fabricated at different heat-treatment temperatures. The glycerin-doped MgB<SUB>2</SUB> wire using milled B powder heat-treated at a solid-state of 600 °C showed the highest transport <I>J</I> <SUB>c</SUB> values at 4.2 K over the entire applied field regime. It was revealed that the grain boundary density was higher and that the C substitution also occurred by a low temperature heat-treatment process, which led to a higher <I>J</I> <SUB>c</SUB>. In addition, a solid–solid diffusion reaction with the pre-treated B powder resulted in poor crystallinity, which enhanced <I>H</I> <SUB>c2</SUB> and improved <I>J</I> <SUB>c</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PIT MgB<SUB>2</SUB>/Fe wires were fabricated using ball-milled and glycerin-treated B powder. </LI> <LI> The influences of heat-treatment temperature were investigated. </LI> <LI> We adopted simultaneously 3 effects of milling, C doping and solid-state reaction. </LI> <LI> Transport <I>J</I> <SUB>c</SUB>, <I>H</I> <SUB>c2</SUB> and <I>H</I> <SUB>irr</SUB> of three effects-adopted MgB<SUB>2</SUB> wire could be enhanced. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>We adopted simultaneously three effects of milling, C doping and solid-state reaction to improve critical current properties of <I>in situ</I> PIT processed MgB<SUB>2</SUB> superconducting wire. As a result, the glycerin-doped MgB<SUB>2</SUB> wire using milled B powder heat-treated at a solid-state of 600 °C showed the highest transport <I>J</I> <SUB>c</SUB> values at 4.2 K over the entire applied field regime. The C incorporation occurred even in a low temperature solid-state process of 600 °C, thus resulting in an improvement of the superconducting properties by obtaining both high grain boundary pinning and C substitution effect.</P> <P>[DISPLAY OMISSION]</P>

Preparation and Characterization of High Molecular Weight Poly(trimethylene terephthalate) by Solid-state Polymerization

Kim, Seok-Hoon,Kim, Joon-Ho 한국섬유공학회 2010 Fibers and polymers Vol.11 No.2

Solid-state polymerization of poly(trimethylene terephthalate)(PTT) was carried out to obtain high molecular weight polymers. Two kinds of commercial PTT chips were polymerized in the solid state by the heat treatment at 190~$220^{\circ}C$ for various times and they were characterized by end group content, molecular weight, thermal analysis, and X-ray diffraction. In the solid-state polymerization of PTT, the overall reaction rate was governed by the solid-state polymerization temperature and time, and pellet size. The content of carboxyl end groups decreased during the solid-state polymerization with increasing solid-state polymerization temperature and time. The melting temperature and crystallinity of the PTT were higher for the ones treated at higher temperature and longer time. The activation energy for the solid-state polymerization of PTT was in the range of 24~25 kcal/mol for both chips. Through the solid-state polymerization of commercial PTT chips, high molecular weight polymers up to an intrinsic viscosity of 1.63 dl/g was obtained, which corresponded to about a 117,000 weight-average molecular weight.

고상반응법에 의한 아커마나이트 분말의 합성 및 생체활성도 평가

고재은,이종국,Go, Jaeeun,Lee, Jong Kook 한국결정성장학회 2022 한국결정성장학회지 Vol.32 No.5

Zirconia and titanium alloys, which are mainly used for dental implant materials, have poor osseointegration and osteogenesis abilities due to their bioinertness with low bioactivity on surface. In order to improve their surface bioinertness, surface modification with a bioactive material is an easy and simple method. In this study, akermanite (Ca₂MgSi₂O₇), a silicate-based bioceramic material with excellent bone bonding ability, was synthesized by a solid-state reaction and investigated its bioactivity from the analysis of surface dissolution and precipitation of hydroxyapatite particles in SBF solution. Calcium carbonate (CaCO₃), magnesium carbonate (MgCO₃), and silicon dioxide (SiO₂) were used as starting materials. After homogeneous mixing of starting materials by ball milling and the drying of at oven, uniaxial pressing was performed to form a compacted disk, and then heat-treated at high temperature to induce the solid-state reaction to akermanite. Bioactivity of synthesized akermanite disk was evaluated with the reaction temperature from the immersion test in SBF solution. The higher the reaction temperature, the more pronounced the akermanite phase and the less the surface dissolution at particle surface. It resulted that synthesized akermanite particles had high bioactivity on particle surface, but it depended on reacted temperature and phase composition. Moderate dissolution occurred at particle surfaces and observed the new precipitated hydroxyapatite particles in synthetic akermanite with solid-state reaction at 1100℃.

Synthesis of Cu₂ZnSnSe₄ compound by solid state reaction using elemental powders

Wibowo, Rachmat Adhi,Alfaruqi, Muhammad H.,Jung, Woon-Hwa,Kim, Kyoo-Ho 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06

Commercially available elemental powders of Cu, Zn, Sn and Se were employed for crystallizing a stannite-type Cu₂ZnSnSe₄ compound by means of solid state reaction. Cu₂ZnSnSe₄ reaction chemistry was also modeled based on differential-thermal analysis and X-ray powder diffraction results. It was observed that Se tends to react preferably with Cu to form CuSe and CuSe₂ phases at low reaction temperature. The formation of Cu₅Zn_8 intermetallic phase was found to be the intermediate reaction path for the binary ZnSe formation. A solid state reaction at 320?C reacted elemental powderst obinary selenides of CuSe, ZnSe and SnSe completely. The crystallization of Cu₂ZnSnSe₄ was was detected to begin at 300?C and its weight fraction increased with an increase of reaction temperature, which most probably formed from the reaction between Cu₂SnSe₃ and ZnSe.

Solid-state reaction between MoS2 and MoO3 in a fluidized bed reactor

이재랑,김용하,원용선 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.9

MoO2 was produced by mixing MoS2 and MoO3 via a solid-state reaction in a fluidized bed reactor. The basic fluidization data were acquired by monitoring the minimum fluidization velocity of MoS2 and MoO3. The conversion rate of MoS2 and MoO3 to MoO2 was derived based on the solid-state reactions carried out for 1 h at various stoichiometric ratios. This study confirmed that the optimal stoichiometric ratio of MoS2 and MoO3 was 1.0 : 6. The conversion rate at the optimum stoichiometric ratio was studied by varying the reaction temperature. A conversion rate of 99% was achieved when the reaction temperature and superficial gas velocity were 973 K and 0.3m/s, respectively. Detailed analysis of the final product after the solid-state reaction was by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD), to determine the shape, structure, and diffraction patterns.

Template-engaged solid-state synthesis of barium–strontium silicate hexagonal tubes

Chen, Xuncai,Kim, Woo-Sik Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.647 No.-

<P><B>Abstract</B></P> <P>Solid materials with hollow structures are of significant interest due to their beneficial features, such as a high surface to volume ratio, high void space in the structure, and low apparent density, allowing such applications as high efficiency catalysts and drug delivery agent. This study presents a new synthetic method for generating hexagonal hollow tubes of (BaSr)SiO<SUB>4</SUB> via a template-engaged solid–solid reaction. First, the composition tuneable (BaSr)CO<SUB>3</SUB> hexagonal rods were prepared as the template by the co-precipitation of Ba<SUP>2+</SUP>, Sr<SUP>2+</SUP>, and then uniformly shelled with the silica (SiO<SUB>2</SUB>) using CTAB, thereby forming (BaSr)CO<SUB>3</SUB>–SiO<SUB>2</SUB> core–shell rods. The SiO<SUB>2</SUB> shell thickness is adjustable based on the TEOS concentration in the sol–gel process. The (BaSr)CO<SUB>3</SUB>–SiO<SUB>2</SUB> core–shell rods were converted to the (BaSr)SiO<SUB>4</SUB> hexagonal hollow tubes by an interfacial solid–solid reaction between the (BaSr)CO<SUB>3</SUB> core and SiO<SUB>2</SUB> shell at 750 °C. During this interfacial solid–solid reaction, the (BaSr)CO<SUB>3</SUB> hexagonal rods are the template for hexagonal tubes of (BaSr)SiO<SUB>4</SUB>. Kirkendall effect contributes to the formation of hollow tube structure of (BaSr)SiO<SUB>4</SUB>. The proposed synthetic method demonstrated a significant advantage for the preparation of (BaSr)SiO:Eu<SUP>2+</SUP> phosphor, where the synthetic temperature was reduced from 1200 °C to 500 °C when compared with the conventional method. The photoluminescence property of the hollow tubular (BaSr)SiO:Eu<SUP>2+</SUP> showed a green emission between 480 nm and 600 nm with the maximum peak intensity at 517 nm under UV excitation. This synthetic method could also be applied to the preparation of hollow-structured multi-component metal silicates.</P>

Effect of starting materials on the properties of solid-state reacted barium titanate powder

Hyun-Tae Kim,Jong-Hyun Kim,Won-Sik Jung,윤당혁 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6

This study examined the effects of the combination of starting materials on the properties of solid-state reacted BaTiO3 using two different types of BaCO3 and TiO2. The reaction temperature was evaluated by thermal gravimetry/differential thermal analysis (TG/DTA). In addition, the effect of mechanochemical activation by high energy milling and the Ba/Ti molar ratio on the reaction temperature, particle size and tetragonality were investigated. TG/DTA demonstrated that the TiO2 phase and size plays a major role in decreasing the reaction temperature and particle size. With the optimum selection of starting materials and processing conditions, BaTiO3 with a particle size < 200 nm and a tetragonality (= c/a) of approximately 1.008 was obtained. This study examined the effects of the combination of starting materials on the properties of solid-state reacted BaTiO3 using two different types of BaCO3 and TiO2. The reaction temperature was evaluated by thermal gravimetry/differential thermal analysis (TG/DTA). In addition, the effect of mechanochemical activation by high energy milling and the Ba/Ti molar ratio on the reaction temperature, particle size and tetragonality were investigated. TG/DTA demonstrated that the TiO2 phase and size plays a major role in decreasing the reaction temperature and particle size. With the optimum selection of starting materials and processing conditions, BaTiO3 with a particle size < 200 nm and a tetragonality (= c/a) of approximately 1.008 was obtained.

Effective synthesis to fabricate a giant dielectric-constant material CaCu3Ti4O12 via solid state reactions

Wen Xiang Yuan,Wai Ning Mei,Sui Kong Hark 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.5

In this study, we effectively synthesized a giant dielectric-constant material CaCu3Ti4O12 (CCTO) by using a solid-state reaction method that was composed of two main chemical reactions. Comparing with typical calcining conditions, our procedures are much less energy- and time-consuming. When preparing our CCTO, we applied a momentarily high temperature heating at the end of the calcination, then followed it by a typical sintering process. We found this additional heating converts the otherwise mixed-phase products into a pure phase and the CCTO samples prepared this special way possess a large dielectric constant, up to 19,000. In this study, we effectively synthesized a giant dielectric-constant material CaCu3Ti4O12 (CCTO) by using a solid-state reaction method that was composed of two main chemical reactions. Comparing with typical calcining conditions, our procedures are much less energy- and time-consuming. When preparing our CCTO, we applied a momentarily high temperature heating at the end of the calcination, then followed it by a typical sintering process. We found this additional heating converts the otherwise mixed-phase products into a pure phase and the CCTO samples prepared this special way possess a large dielectric constant, up to 19,000.

The study on the interface characteristics of solid-state electrolyte

Lim Hyung-Sik,Liu Liyu,Lee Hyun-Joon,Cha Jae-Min,Yoon Duck-ki,류봉기 한국세라믹학회 2021 한국세라믹학회지 Vol.58 No.3

Solid electrolytes for all-solid-state lithium batteries are excellent in terms of stability, and their performance has been improved through many studies. However, due to the interfacial reaction with lithium and sold electrolyte, there is a problem that the performance is deteriorated when used for a long time. In this study, the charge/discharge evaluation of more than 50 cycles was conducted and we analyzed the change Ti 4+ to Ti 3+ in the solid electrolyte using X-ray photoelectron spectroscopy. Finally, it was confirmed that the performance of the LiNbO 3 -coated solid electrolyte did not decrease even after long-term use.

고상법에 의한 100 nm BaTiO₃ 분말의 합성

김정환,정한승,조준엽,홍정오,김영태,허강헌 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.2

BaTiO₃ powder was synthesized by the solid-state reaction of fine BaCO₃ and TiO₂ raw materials. Fine grinding media of 50 and 300 microns were used for obtaining fine particulate mixture of BaCO₃ and TiO₂ with high homogeneity. Effect of the size of grinding media on the synthesis mechanism of BaTiO₃ was discussed on the basis of the particulate morphology and thermogravimetry data for the mixture powders. By using the finer grinding media, BaTiO₃ was formed at the lower temperature and the particle size with the relatively narrower distribution could be obtained. BaTiO₃ powder with the average size of 100 nm was synthesized by the solid reaction in vacuum atmosphere. BaTiO₃ powder was synthesized by the solid-state reaction of fine BaCO₃ and TiO₂ raw materials. Fine grinding media of 50 and 300 microns were used for obtaining fine particulate mixture of BaCO₃ and TiO₂ with high homogeneity. Effect of the size of grinding media on the synthesis mechanism of BaTiO₃ was discussed on the basis of the particulate morphology and thermogravimetry data for the mixture powders. By using the finer grinding media, BaTiO₃ was formed at the lower temperature and the particle size with the relatively narrower distribution could be obtained. BaTiO₃ powder with the average size of 100 nm was synthesized by the solid reaction in vacuum atmosphere.