Establishment of strongly overdoped states in the HgBa2Ca2Cu3O8+δ superconductor
Loading...
Access rights
openAccess
URL
Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This publication is imported from Aalto University research portal.
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
Other link related to publication (opens in new window)
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
Other link related to publication (opens in new window)
Date
1997-12-01
Major/Subject
Mcode
Degree programme
Language
en
Pages
7
14790-14796
14790-14796
Series
PHYSICAL REVIEW B, Volume 56, issue 22
Abstract
Strongly overdoped HgBa2Ca2Cu3O8+δ (Hg-1223) samples with superconducting transitions as low as 97 K were successfully obtained by using HgO, Ca2CuO3, CuO, and mixtures of highly oxidized BaCuO2+∈ (∈ ≈0.13) and/or BaO2 powders as starting materials for the high-pressure synthesis at 5 CPa and 950°C. The overdoped state was confirmed by observing negative values for the Seebeck coefficient throughout the temperature range from Tc to 320 K in a thermoelectric power measurement. Also, both of the cell parameters a and c were found to decrease with decreasing Tc, reflecting, respectively, an increase in hole concentration in the CuO2 planes and the incorporation of oxygen into the HgOδ layer. The oxygen excess δ as determined by the Cu(+I)/Cu(+II) coulometric titration method, was ∼0.19 in the overdoped sample with Tc=107 K. Subsequent reducing annealing in an Ar atmosphere at 280°C increased the Tc to 131 K. Consistently, only positive Seebeck coefficient values were observed up to 320 K for the Ar-annealed sample. A clearly underdoped material with Tc=118 K was obtained by annealing the same sample in Ar at a higher temperature (∼400°C). Finally, high-pressure synthesis starting from less-oxidized BaCuO2+∈ (∈≈0.06) yielded a Hg-1223 material with δ≈0.10 and Tc= 132 K.Description
Keywords
Other note
Citation
Fujinami , K , Ito , T , Suematsu , H , Matsuura , K , Karppinen , M & Yamauchi , H 1997 , ' Establishment of strongly overdoped states in the HgBa 2 Ca 2 Cu 3 O 8+δ superconductor ' , Physical Review B , vol. 56 , no. 22 , pp. 14790-14796 . https://doi.org/10.1103/PhysRevB.56.14790