The structure of $YBa_2Cu_3O_x$ superconductor varies with temperature and the value of x. The value of x increases with the decreases of final heat treatment temperature and the increasement of oxygen partial pressure. Orthorhombic-tetragonal transformation occurs at x = 6.63 ± 0.05. This transformation results from the order-disorder transition of oxygen atoms at basal plane. As x increases, the volume of unitecell as well as the number of oxygen vacancies increases. Hence, if synthesis and sintering of $YBa_2Cu_3O_x$ superconductor is controlled by diffusion of atoms, it is expected that rate will increase as the value of x decreases or oxygen partial pressure ecreases.
In this experiment, we study the synthesis and sintering of the superconductor under oxygen atmosphere and inert atmosphere. The specimens which were synthesixed with powder mixture of $Y_2O_3$, $BaCO_3$ and CuO sintered under different atmospheres were investigated with optical microscopic, X- ray powder diffraction analysis and TG analysis. as expected, the synthesis, grain growth and dencification of superconducting material occur more rapidly under inert atmosphere than under oxygen atmosphere.
In conclusion, the oxide superconductor can be made easily at a relatively low temperature when it is calcined and sintered under inert atmosphere.
