Structure, superconductivity and magnetism of YBa2(Cu1−xMx)4O8 (MFe, Co, Ni, Zn and Ga)

✍ Scribed by T.H. Meen; F.L. Juang; W.J. Huang; Y.C. Chen; K.C. Huang; H.D. Yang

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 512 KB
• Volume: 242
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)02426-x

✦ Synopsis

YBa2 ( Cu ~ _ xMx ) 4Os ( M = Fe, Co, Ni, Zn and Ga; 0 ~< x ~< 0.05 ) h ave been investigated by means of X-ray diffraction, electrical-resistivity and magnetic-susceptibility measurements. X-ray-diffraction patterns show that all samples studied contain the nearly single 124 phase. They exhibit an orthorhombic-to-tetragonal structural transition at about x= 0.03 for M = Fe and Co; and at x=0.04 for M=Ga; while the structure remains orthorhombic at x=0.05 for M=Ni and Zn. These results suggest that Fe, Co and Ga substitute preferentially for [Cu( 1 ) ] sites, and the Ni and Zn prefer to occupy the [Cu(2) ] sites. The initial depression rates of T~o (temperature of zero resistance) with increasing doping concentration for various dopants are 16.85, 8.4, 23.75, 12 and 3.9 K/at.% for M = Fe, Co, Ni, Zn and Ga, respectively. Effective magnetic moments of YBa2 (Cu0.97Mo.o3)408 are 5.63, 3.91 and 3.37/aB for M =Fe, Co and Ni, respectively. In addition, the similarities and differences between YBa2(Cul _xMx)408 and YBa2 (Cut -xMx) 307 -y are discussed.