Fabrication of melt-texture growth YBCO samples using a simple muffle furnace

Abstract

In our previous work we showed that gradients of temperatureT inside the heating chamber and∂T/∂t are the necessary conditions for growing oriented crystal layers inside bulk samples. Using a simple muffle furnace, we have successfully fabricated “layers” of YBCO samples. Powder layers of Y-123 and Y-211 in different structures were compressed to make sample pellets before heat treatment in order to create internal temperature gradients inside the samples when they were heated. SEM observation proved that the crystal layers grew from both the top and bottom surfaces of the sample independently of the original powder layers before heat treatment. Moreover, we found that the crystal layers are not “true layers” but “bulk crystal with gap lines.” EDX analysis confirmed that the 123 and 211 phases coexist in almost all of the samples. Using the concept of internal temperature gradients, we show that it is possible to carry out modified melt-texture growth even in a muffle furnace.