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Synthesis and superconducting properties of Nd0.33Eu0.08Gd0.58Ba2Cu3Oz materials

100%

Stoyanova-Ivanova A., Terzieva S., Shivachev B., Mikli V., Vladimirova L.

Open Physics

2008

vol. 6

issue 1

76-79

We have studied the effect of the ratio of different rare-earth element on the superconducting properties and phase formation of (Nd0.33Eu0.08Gd0.58)Ba2Cu3Oz ceramic. Bulk NEG samples were prepared using the solid-state reaction process. The superconducting transition for Nd0.33Eu0.08Gd0.58Ba2Cu3Oz is T c ≈90 K and the value of the critical current density (J c) is 13.9 A/cm2 at 77 K under zero magnetic fields. This value is twice as high when compared with the (J c) value of YBCO systems (J c = 7.31 A/cm2). The obtained bulk sample was used for the production of superconducting Ag-sheathed tapes by OPIT method including hot rolling. The critical current density of the obtained tape (337 A/cm2) is one order higher than the one of the bulk sample.

pH impact on the sol-gel preparation of calcium hydroxyapatite, Ca10(PO4)6(OH)2, using a novel complexing agent, DCTA

86%

Bogdanoviciene I., Tőnsuaadu K., Mikli V., Grigoraviciute-Puroniene I., Beganskiene A., Kareiva A.

Open Chemistry

2010

vol. 8

issue 6

1323-1330

Aqueous sol-gel chemistry routes - based on ammonium hydrogen phosphate as the phosphorus precursor, calcium acetate monohydrate as the source of calcium ions, and 1,2-diaminocyclohexanetetraacetic acid monohydrate (DCTA) as the complexing agent - have been used to prepare calcium hydroxyapatite (HA). The sol-gel process was performed in aqueous solution at different pH values followed by calcination of the dry precursor gels for 5 h at 1000°C. Phase transformations, composition, and structural changes in the polycrystalline samples were studied by thermoanalytical methods (TG/DTA), infrared spectroscopy (IR), X-ray powder diffraction analysis (XRD), and scanning electron microscopy (SEM). It was shown that pH adjustment has significant impact on the apatite formation process and on the morphology and phase purity of the ceramic samples.

Microstructure and thermal properties of quasi-equal rare earth substitution Y0.5Gd0.5Ba2Cu3O6.94 superconductor

86%

Terzieva S., Stoyanova-Ivanova A., Shivachev B., Terzijska B., Zaleski A., Misiorek H., Mikli V.

Open Physics

2009

vol. 7

issue 1

84-88

Sintering effects in YBa2Cu3Oz samples with quasi-equal rare earth substitution have been investigated. It has been shown that the Y-123 type compound can be formed when gadolinium is partially substituted (in this case 50% atomic substitution) for yttrium. The superconducting compound was obtained by the optimized ceramic method, including solid-state reaction, melting and sintering, controlled by X-ray diffraction. The microstructure was investigated by SEM and energy dispersive X-ray analyses. An AC susceptibility measurement has shown that T c =93 K. Temperature-dependece of the thermal conductivity (4.5–300 K) of the polycrystalline Y0.5Gd0.5Ba2Cu3O6.94 sample was also measured.

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2 Open Physics

1 Open Chemistry

1 2010

1 2009

1 2008

3 Mikli V.

2 Shivachev B.

2 Stoyanova-Ivanova A.

2 Terzieva S.

1 Beganskiene A.

1 Bogdanoviciene I.

1 Grigoraviciute-Puroniene I.

1 Kareiva A.

1 Misiorek H.

1 Terzijska B.

1 Tőnsuaadu K.

1 Vladimirova L.

1 Zaleski A.

Search results

Synthesis and superconducting properties of Nd0.33Eu0.08Gd0.58Ba2Cu3Oz materials

pH impact on the sol-gel preparation of calcium hydroxyapatite, Ca10(PO4)6(OH)2, using a novel complexing agent, DCTA

Microstructure and thermal properties of quasi-equal rare earth substitution Y0.5Gd0.5Ba2Cu3O6.94 superconductor