Contrasting effects of Ca2+ and Ho3+ substitutions on superconductivity and excess conductivity of (Ho1-xCa x)(Ba2-yHoy)Cu3O7-δ

• Published in: AIP Conference Proceedings
• Main Author: Maulud M.F.; Hamidi Z.S.; Yusof A.A.; Yusof M.I.M.; Yahya A.K.
• Format: Conference paper
• Language: English
• Published: 2010
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650103049&doi=10.1063%2f1.3469720&partnerID=40&md5=e0dde47997afafdc5e88df11665eb65a

Effects of Ho3+ and Ca2+ substitutions in (Ho 1-xCax)(Ba2-yHoy)Cu 3O7-δ ceramics on normal and superconducting state behaviour were investigated. Electrical resistivity measurements showed increasing Ho3+ substitution at Ba2+ site (x=0, 0.4, y=0-0.4) caused normal state resistivity to change from metal-like to semimetal/semiconductor-like behaviour and suppressed Tc from 89 K (y=0) to 72 K (y=0.4) while substitution of Ca2+ for Ho3+ ((x=0.2) 0.4, (y=0.4)) revives metallic behaviour of the normal state with increasing x. Excess conductivity analysis based on Asmalazov-Larkin theory showed 2D to 3D transition for all superconducting samples but with contrasting effects of the substitutions on AL2D and AL3D constants. The resistivity and excess conductivity results indicate effective hole filling Ho3+ and hole doping by by Ca2+ substitutions. © 2010 American Institute of Physics.