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

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)K_xCu₃O_y (x = 0-0.40) were investigated. The ac complex susceptibility χ_ac = 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 - T_m/T_c)ⁿ, where T_m 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 ≤ μ₀H_a ≤ 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.