Effect of hafnium doping on the phase composition and superconducting characteristics of yttrium-based ceramics
Аннотация
The possibility of synthesizing a ceramic with composition Y1Ba2Cu3–xHfx O7–δ (0 ≤ x ≤ 2) is investigated. The synthesis was carried out by using oxides according to standard ceramic technology. The material was annealed for six hours at a temperature of 945 °C. The obtained samples were used for x-ray and magnetic measurements. The x-ray structural analysis showed that for a hafnium concentration x ≤ 0.2 the samples contain the standard rhombic phase (1–2–3) and the “green phase” (not more than 10%). An increase in the hafnium concentration leads to the emergence of two new phases, viz., BaHfO3 and Ba2HfO4, whose amount increases considerably with increasing x. The superconducting transition temperature (dynamic susceptibility measurements) decreases from 91 K (initial ceramic) to 82.3 (for x = 1.0). For higher Hf concentrations, a superconducting transition in the samples is not observed.