Nd substitution effects in YBa2Cu4O8 prepared using a conversion reaction from Y1-xNdxBa2Cu3O7-delta and CuO
2000 (English)In: International Journal of Inorganic Materials, ISSN 1466-6049, Vol. 2, no 2-3, 269-276 p.Article in journal (Refereed) Published
Synthesis, crystal structure and magnetic properties of samples with partial substitution of Nd for Y in YBa2Cu4O8 are considered. The samples with nominal composition Y1-xNdxBa2Cu4O8 (x=0.0-0.75) were prepared using a solid state conversion reaction from Y1-xNdxBa2Cu3O7-8 and CuO using LiF as a flux. The annealing was performed at 790 degrees C in a flowing oxygen atmosphere. The products with x=0.0-0.5 showed thermal stability up to 660 degrees C in N-2(g) atmosphere revealing a single phase composition. The success of the synthesis is considered in relation to the effective ionic size of the Nd3+ ion. The crystal structures of the compounds are described on the basis of powder neutron diffraction measurements. The T-c values of the Nd substituted samples were noticeably lower than for the pristine YBa2Cu4Odelta. Possible reasons for the decrease in T-c are discussed on the basis of calculated values for hole concentrations in the Cu-O-2 planes obtained via the BVS (bond valence sum) method, and on the basis of some Nd3+ ions being introduced at Ba2+ ion sites in the lattice.
Place, publisher, year, edition, pages
2000. Vol. 2, no 2-3, 269-276 p.
superconductors, neutron diffraction, powder neutron-diffraction, oxygen-pressure, crystal-structure, superconductor yba2cu4o8, t-c, phase, gd, ho, dy, temperature
IdentifiersURN: urn:nbn:se:kth:diva-19840ISI: 000087700300014OAI: oai:DiVA.org:kth-19840DiVA: diva2:338532
QC 201005252010-08-102010-08-10Bibliographically approved