Low temperature fluorination of (Sr,Ba)2CuO3 using NH4F

S. Adachi, T. Tatsuki, T. Sugano, Ayako Yamamoto, K. Tanabe

Research output: Contribution to journalArticle

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Abstract

Low temperature fluorination of Sr2-xBaxCuO3 (x = 0.0-0.6) was carried out. The pristine samples were heat-treated with NH4F at 210 °C in flowing nitrogen gas. The major phase was drastically changed to the K2NiF4 type, one with poor crystallinity. The fluorinated samples exhibited Meissner signals, but the signal intensity was too low to identify the corresponding superconducting phase correctly. A maximum Tc of 68 K was detected in the fluorinated sample with x = 0.2, being different from Slater et al.'s previous result in which the fluorinated sample with x = 0.6 exhibited the maximum Tc of 64 K. The crystallite size of the K2NiF4 phase in the fluorinated sample with x = 0.2 was estimated to be about 220 angstroms from a broad peak of the 220 reflection in the X-ray powder diffraction (XRD) pattern. It is considered that the major phase with the K2NiF4 structure is responsible for the observed superconductivity and the small Meissner signals were attributed to the small grain size. In 6 months, the orthorhombicity of the K2NiF4 phase in the fluorinated sample with x = 0.2 increased and the observed Tc was appreciably lowered. This correspondence between the orthorhombicity and Tc also implies that the detected Meissner signals came from the K2NiF4 phase.

Original languageEnglish
Pages (from-to)87-94
Number of pages8
JournalPhysica C: Superconductivity and its Applications
Volume334
Issue number1
DOIs
Publication statusPublished - 2000 Jun 1
Externally publishedYes

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Fluorination
fluorination
Crystallite size
Superconductivity
X ray powder diffraction
Diffraction patterns
Nitrogen
Gases
Temperature
Hot Temperature
crystallinity
diffraction patterns
superconductivity
grain size
nitrogen
heat
gases
x rays

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Low temperature fluorination of (Sr,Ba)2CuO3 using NH4F. / Adachi, S.; Tatsuki, T.; Sugano, T.; Yamamoto, Ayako; Tanabe, K.

In: Physica C: Superconductivity and its Applications, Vol. 334, No. 1, 01.06.2000, p. 87-94.

Research output: Contribution to journalArticle

Adachi, S. ; Tatsuki, T. ; Sugano, T. ; Yamamoto, Ayako ; Tanabe, K. / Low temperature fluorination of (Sr,Ba)2CuO3 using NH4F. In: Physica C: Superconductivity and its Applications. 2000 ; Vol. 334, No. 1. pp. 87-94.
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