Effects of calcium doping on the superconducting properties of top-seeded melt growth processed Y_1.5Ba_2-xCa_xCu₃O_y superconductors

Park, S.D.,Kim, H.J.,Park, B.J.,Han, Y.H.,Jun, B.H.,Lee, J.S.,Kim, C.J. North-Holland 2011 Physica. C, Superconductivity Vol.471 No.21

The effect of calcium doping on the superconducting properties of top seeded melt growth (TSMG) processed Y<SUB>1.5</SUB>Ba<SUB>2-x</SUB>Ca<SUB>x</SUB>Cu<SUB>3</SUB>O<SUB>y</SUB> superconductors was studied in terms of calcium content (X<SUB>ca</SUB>). YBa<SUB>2-x</SUB>Ca<SUB>x</SUB>Cu<SUB>3</SUB>O<SUB>7-δ</SUB> (X<SUB>ca</SUB>=0, 0.005, 0.01, 0.02, 0.04, 0.1, 0.3) powders were synthesized by the powder calcination method. YBa<SUB>2-x</SUB>Ca<SUB>x</SUB>Cu<SUB>3</SUB>O<SUB>7-δ</SUB> powders were mixed with 0.25mole Y<SUB>2</SUB>O<SUB>3</SUB> powder and 1wt.% CeO<SUB>2</SUB> as Y<SUB>2</SUB>BaCuO<SUB>5</SUB> (Y211) refiner, and finally made into Y<SUB>1</SUB>.<SUB>5</SUB>Ba<SUB>2-x</SUB>Ca<SUB>x</SUB>Cu<SUB>3</SUB>O<SUB>y</SUB> (Y1.5)+1wt.% CeO<SUB>2</SUB> composition. The single Y123 growth on the top surface was observed up to X<SUB>ca</SUB>=0.1, while the multiple Y123 growth was observed at X<SUB>ca</SUB>≥0.1. The superconducting transition temperature (T<SUB>c</SUB>) and critical current density (J<SUB>c</SUB>) of TSMG processed Y1.5 samples were inversely proportional to X<SUB>ca</SUB>. The Y211 size increased with increasing X<SUB>ca</SUB> due to the enhancement of Y211 coarsening by calcium doping. No Y211 refining effect by CeO<SUB>2</SUB> was observed in the calcium doped samples. The T<SUB>c</SUB> and J<SUB>c</SUB> decrease by calcium doping are likely to be due to the calcium incorporation with the Y123 lattice and formation of coarse Y211 particles.

Effect of Ca doping on the thermoelectric properties of SrCu2O2

Octolia Togibasa Tambunan,김일호,이보화,유춘리 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3

The thermoelectric properties of p-type oxide SrCu2O2 doped with Ca with amounts of 0, 3, 10, and 15% have been studied. The Seebeck coefficients were found to be positive for all the samples in the temperature range between 423 and 923 K. Although no effective enhancement of the electrical conductivity was observed, doping with Ca clearly improved the Seebeck coefficients and the thermal conductivity of SrCu2O2. SrCu2O2 doped with 10% Ca showed the lowest thermal conductivity that varied from 0.32 W/mK at 423 K to 0.66 W/mK at 923 K. Overall, the value of ZT of Ca-doped SrCu2O2 was slightly larger than that of the un-doped SrCu2O2. SrCu2O2 doped with 15% of Ca showed the highest ZT of 2.67×10-3 at 423 K and 4.38×10-3 at 923 K. The thermoelectric properties of p-type oxide SrCu2O2 doped with Ca with amounts of 0, 3, 10, and 15% have been studied. The Seebeck coefficients were found to be positive for all the samples in the temperature range between 423 and 923 K. Although no effective enhancement of the electrical conductivity was observed, doping with Ca clearly improved the Seebeck coefficients and the thermal conductivity of SrCu2O2. SrCu2O2 doped with 10% Ca showed the lowest thermal conductivity that varied from 0.32 W/mK at 423 K to 0.66 W/mK at 923 K. Overall, the value of ZT of Ca-doped SrCu2O2 was slightly larger than that of the un-doped SrCu2O2. SrCu2O2 doped with 15% of Ca showed the highest ZT of 2.67×10-3 at 423 K and 4.38×10-3 at 923 K.

Ca-doped Na_xCoO₂ for improved cyclability in sodium ion batteries

Han, Su Cheol,Lim, Heatsal,Jeong, Jaehyang,Ahn, Docheon,Park, Woon Bae,Sohn, Kee-Sun,Pyo, Myoungho Elsevier 2015 Journal of Power Sources Vol.277 No.-

<P><B>Abstract</B></P> <P>Na<SUB>x</SUB>Ca<SUB>y</SUB>CoO<SUB>2</SUB> (0.45 ≤ <I>x</I> ≤ 0.64, 0.02 ≤ <I>y</I> ≤ 0.10) is synthesized via a solid-state method and examined as a cathode material to improve the cyclability of sodium ion batteries (SIBs). The substitution of one Ca<SUP>2+</SUP> for two Na<SUP>+</SUP> does not alter the P2-phase of undoped Na<SUB>0.73</SUB>CoO<SUB>2</SUB>, accompanying the continuous contraction of the unit cell volume with Ca-doping. The existence of Ca<SUP>2+</SUP> in the prismatic sites between CoO<SUB>6</SUB> slabs also affects the phase transition behaviors during charge–discharge (C–D). The suppression of Na<SUP>+</SUP>-vacancy ordering, ascribed to the immobility of Ca<SUP>2+</SUP> in Na<SUB>x</SUB>Ca<SUB>y</SUB>CoO<SUB>2</SUB>, leads to continuous changes of the cell voltages with no abrupt voltage drops during C–D. The reduced cell dimension and the mitigation of distinctiveness between biphasic and solid-solution domains during C-D improve the cyclability of Na<SUB>x</SUB>Ca<SUB>y</SUB>CoO<SUB>2</SUB> in SIBs. As an example, the negligible capacity fading in Na<SUB>0.60</SUB>Ca<SUB>0.07</SUB>CoO<SUB>2</SUB> during 60 cycles (0.07 mAh g<SUP>−1</SUP> cycle<SUP>−1</SUP>) is contrasted with a substantial decrease in the reversible capacity of Na<SUB>0.73</SUB>CoO<SUB>2</SUB> (0.56 mAh g<SUP>−1</SUP> cycle<SUP>−1</SUP>). Furthermore, a slower Na<SUP>+</SUP> diffusion of Na<SUB>x</SUB>Ca<SUB>y</SUB>CoO<SUB>2</SUB> in Na<SUP>+</SUP>-vacancy ordering regions, is sufficiently offset by a more rapid diffusion in all the other regions, which results in an improved rate performance. The platform presented here (multi-valent cation substitution for Na<SUP>+</SUP>) could be utilized in other layered cathode materials to improve the electrochemical performance of SIBs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Na<SUB>x</SUB>Ca<SUB>y</SUB>CoO<SUB>2</SUB>, synthesized by a solid-state method, is examined as a cathode in SIBs. </LI> <LI> Ca<SUP>2+</SUP> substituted for two Na<SUP>+</SUP> enhances structural stability during cycling. </LI> <LI> Ca-doping contracts the cell dimensions and suppresses abrupt phase transitions. </LI> <LI> Na<SUB>0.6</SUB>Ca<SUB>0.07</SUB>CoO<SUB>2</SUB> shows the best cyclability (from 105 to 101 mAh g<SUP>−1</SUP> for 60 cycles). </LI> <LI> Na<SUB>0.6</SUB>Ca<SUB>0.07</SUB>CoO<SUB>2</SUB> also shows a better rate performance than undoped Na<SUB>0.73</SUB>CoO<SUB>2</SUB>. </LI> </UL> </P>

Effect of Calcium Doping in Low Angle Grain Boundaries of $YBa_2$$Cu_3$$O_{7-$\delta$}$on Textured Metal Substrates

Kang, B.W.,A. Goyal,F.A. List,D.K. Christen,H. R. Kerchner,S. Sathyamurthy,Lee, D.F.,Martin, P.M.,Koreger, D.M. The Korean Superconductivity Society 2002 Progress in superconductivity Vol.4 No.1

We report the effect of Ca doping in $YBa<_2$$Cu_3$O/sub 7-$\delta$/ (YBCO) thin films grown on the Rolling- Assisted, Biaxially Textured Substrates (RABiTS) with the architecture of $CeO_2$/YSZ/CEO$_2$/Ni. Critical currents of bilayer and trilayer structures of YBCO/Y/sub 0.7/Ca/sub 0.3/$Ba_2$$Cu_3$O/sub 7-$\delta$/ (YCaBCO) as well as undoped YBCO for comparison have been measured in a wide range of temperatures and fields. For $6-8^{\circ}$ grain boundaries, 30% Ca-doping in bilayer structure enhances Jc as high as 35 %. The enhancement is larger at low temperatures and at magnetic fields. On the other hand, 30% Ca-doping in trilayer structure reduces Jc as high as 60%. Combined with slightly lower Tc, this indicates that Ca is overdoped in this structure and degrades GBs.

Diagnostic Calculation of Trace Calcium Ions in Food Using a DNA doped Sensor

양영균,이수영 한국응용과학기술학회 2013 한국응용과학기술학회지 Vol.30 No.2

The diagnostic assay of calcium ion was sought using a modified sensor with square-wave stripping voltammetry (SWSV) and cyclic voltammetry (CV). In this study, simple graphite pencil was used as working, reference, and auxiliary electrodes. By coating the working electrodes with DNA, their sensitivity was very much improved, and good results were yielded. Moreover, clean seawater was used as an electrolyte solution instead of acid and base electrolytes to lessen the expenses involved in the experiment. The analytical optimum conditions were also examined. These conditions were attained at the low detection limit of 0.6 ugL¹. After that, the results were applied to drinking water of milk contain.

Diagnostic Calculation of Trace Calcium Ions in Food Using a DNA doped Sensor

( Kyun Yang Young ),( Young Ly Suw ) 한국유화학회 2013 한국응용과학기술학회지 Vol.30 No.2

The diagnostic assay of calcium ion was sought using a modified sensor with square-wave stripping voltammetry (SWSV) and cyclic voltammetry (CV). In this study, simple graphite pencil was used as working, reference, and auxiliary electrodes. By coating the working electrodes with DNA, their sensitivity was very much improved, and good results were yielded. Moreover, clean seawater was used as an electrolyte solution instead of acid and base electrolytes to lessen the expenses involved in the experiment. The analytical optimum conditions were also examined. These conditions were attained at the low detection limit of 0.6 ugL¹. After that, the results were applied to drinking water of milk contain.

Diagnostic Calculation of Trace Calcium Ions in Food Using a DNA doped Sensor

Young-Kyun Yang,Suw-Young Ly 한국유화학회 2013 한국응용과학기술학회지 Vol.30 No.2

The diagnostic assay of calcium ion was sought using a modified sensor with square-wave stripping voltammetry (SWSV) and cyclic voltammetry (CV). In this study, simple graphite pencil was used as working, reference, and auxiliary electrodes. By coating the working electrodes with DNA, their sensitivity was very much improved, and good results were yielded. Moreover, clean seawater was used as an electrolyte solution instead of acid and base electrolytes to lessen the expenses involved in the experiment. The analytical optimum conditions were also examined. These conditions were attained at the low detection limit of 0.6ugL1. After that, the results were applied to drinking water of milk contain.

Diagnostic Calculation of Trace Calcium Ions in Food Using a DNA doped Sensor

Yang, Young-Kyun,Ly, Suw-Young The Korean Society of Applied Science and Technolo 2013 한국응용과학기술학회지 Vol.30 No.2

The diagnostic assay of calcium ion was sought using a modified sensor with square-wave stripping voltammetry (SWSV) and cyclic voltammetry (CV). In this study, simple graphite pencil was used as working, reference, and auxiliary electrodes. By coating the working electrodes with DNA, their sensitivity was very much improved, and good results were yielded. Moreover, clean seawater was used as an electrolyte solution instead of acid and base electrolytes to lessen the expenses involved in the experiment. The analytical optimum conditions were also examined. These conditions were attained at the low detection limit of $0.6ugL^1$. After that, the results were applied to drinking water of milk contain.

Transesterification of canola oil and methanol by lithium impregnated CaO–La2O3 mixed oxide for biodiesel synthesis

Hesam Maleki,Mohammad Kazemeini,Afsaneh S. Larimi,Farhad Khorasheh 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.47 No.-

CaO–La2O3 mixed oxides were synthesized by co-precipitation coupled with Li doping through wetimpregnation. These were used as catalysts for transesterification of canola oil and methanol towardbiodiesel production. To determine the structure and morphology of the prepared catalysts, they werecharacterized by the XRD, FESEM, BET, and basic strength measurements. Under optimum reactionconditions of methanol/oil molar ratio of 15:1, 5 wt% catalyst at 65 C, 96.3% conversion was obtained in2.5 h of reaction duration. Moreover, the catalyst demonstrated a rather high stability where reuse of uptofive cycles without significant loss of performance observed.