Magnetic properties of KClO₃-doped Y_(1-0.2x)Ba_(2-0.2x)K_xCu₃O_y, (x= 0-0.40) HTSC

Abstract

The influence of KClO3 addition on the magnetic properties and microstructural parameters (grain size, grain boundaries) of high-temperature superconductors (HTSC) with nominal composition Y(1-0.2x)Ba(2-0.2x)KxCu3Oy (x = 0-0.40) were investigated. The ac complex susceptibility χac = χ'-iχ'' was recorded as a function of temperature and concentration of KClO3 at various ac magnetic fields up to 2 mT. The data were analysed using the relation h = a(1-Tm/Tc)n, where Tm represents the intergranular peak temperature of the imaginary component χ''. The value of a is found to increase for doped samples, which suggests enhanced flux pinning due to the KClO3 addition. The dc susceptibility as a function of temperature was measured by means of a SQUID magnetometer in field-cooled cooling (FCC) and field-cooled warming (FCW) modes in magnetic fields in the range 10 mT⩽µ0Ha⩽7 T on KClO3-doped and pure YBCO samples. The Meissner curves reveal that the samples are single phase in all applied fields, but the low-temperature behaviour of the samples with KClO3 additions is different from that of pure YBCO.