Crystal structure and specific heat of YBa2(Cu1-xZnx)3O7-†(x=0.01 ... 0.1, †=0;0.9)

✍ Scribed by G. Roth; P. Adelmann; R. Ahrens; B. Blank; H. Bürkle; F. Gompf; G. Heger; M. Hervieu; M. Nindel; B. Obst; J. Pannetier; B. Raveau; B. Renker; H. Rietschel; B. Rudolf; H. Wühl

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 171 KB
• Volume: 162-164
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(89)91134-9

✦ Synopsis

Properties of a series of Zn-cloped YBa2Cu307-samples prepared under identical cond tions have been studied by powder neutron diffraction (20 K, 270 K), powder X-ray-and electron diffraction (290 K), by measurements of specific heat Cp (1.4 K-300 K) and Meissner effect (4 K -100 K). Tc decreases linearly at about 10 K/at% Zn. The Meissner signal is still present for high Zn contents. In contrast to this, the transition in CDvanishes at x = 0.03. Zn is quantitatively dissolved even at x = 0.1. The Cu( 1)-(chain-) site incorporates about 50% of the total Zn content, while the two equivalent Cu( 2)-(plane-) sites contain 25% each. The occupancy of the O( 1)-(chain-) site decreases with increasing Zn content according to the approximate formula YBa2(CUl-xZnx)3OT-x/2. This leads to an almost constant average copper ox dation state, independently confirmed by iodometric titration. Our findings are discussed in terms of a transition to gapless superconductivity upon Zn-doping.