Composition, crystal structure and superconducting properties of HgBaCuO and HgBaCaCuO superconductors

Ayako Tokiwa-Yamamoto, Kazuyuki Isawa, Makoto Itoh, Seiji Adachi, H. Yamauchi

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44 Citations (Scopus)

Abstract

The composition, crystal structure and superconducting properties of HgBaCuO and HgBaCaCuO superconductors were investigated. Samples with various nominal compositions were prepared from the mono-oxides of Hg, Ba, Ca and Cu using various sintering processes. The samples were examined by X-ray powder diffraction and energy dispersive X-ray analysis (EDX). The HgBaCuO samples were found to be nearly single phases of HgBa2CuO4+δ (Hg-1201), but the HgBa CaCuO samples contained HgBa2Ca2Cu3O8+δ (Hg-1223), HgBa2CaCu2O6+δ (Hg-1212) and other phases. The fraction of the higher-Tc phase in the HgBaCaCuO sample varied in accordance with the nominal composition. High-resolution transmission electron microscopic (HRTEM) studies revealed the existence of Hg-1201 (tetragonal cell with a=3.85 and c=9.5 A ̊), Hg-1212 (c=12.6 A ̊). and Hg-1223 structures (c=15.7 A ̊). Most of the HgBaCuO samples exhibit 95 K-classs superconductivity, and the Hg BaCaCuO samples showed 130 K-class superconductivity. The highest Meissner onset temperature, Tcm determined from DC susceptibility was 134 K. The same sample showed superconductivity with a ≈ 16% diamagnetic volume fraction at 5 K.

Original languageEnglish
Pages (from-to)250-256
Number of pages7
JournalPhysica C: Superconductivity and its applications
Volume216
Issue number3-4
DOIs
Publication statusPublished - 1993 Nov 1
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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