Sažetak sa skupa
Comparison of dilatometric measurements of YBa₂Cu₃O₇₋ₓ in oxygen, air and argon atmosphere
A. Szytula
; Institute of Physics, Jagellonian University, Cracow, Poland
G. Mavrodiev
; Institute of Physics, Faculty of Sciences, Skopje
S. Koneska
; Institute of Physics, Faculty of Sciences, Skopje
M. Fukarova-Jurukovska
; Institute of Physics, Faculty of Sciences, Skopje
Sažetak
The results of the comparison of the thermal dilatometric measurements for two specimens of YBa₂Cu₃O₇₋ₓ prepared at different conditions – reacting the constituents at 930°C for 18 h (sample I) and 950°C for 24 h (sample II) in air atmosphere and sintering the samples at 950°C for 24 h (sample II) and 900°C (sample II) in flowing oxygen – are presented. The measurements are performed in flowing oxygen, air and argon atmospheres. Experimental results of percentage thermal expansion Δl/l and the coefficient of the linear thermal expansion α show that the phase transition O₁ → O₂ is followed by an increase of Δl/l and α, while their values decrease by the O₂ → T phase transformation. A hysteresis effect by heating and cooling is observed (especially strong in argon). Independent on the gas atmosphere, the O₁ → O₂ phase transition takes place at about 400°C for the sample I. For the sample II in oxygen this transition takes place at 575°C and in air it is completed at 550°C. O₂ → T phase transition temperature for sample II is higher than the one for sample I and it decreases with the gas atmosphere changing: oxygen → air → argon.
Ključne riječi
Hrčak ID:
338938
URI
Datum izdavanja:
20.12.1989.
Posjeta: 173 *