The size and morphology of silver in the YBa 2Cu 3O 6+ x crystal

Abstract

The effect of Ag 2O and Y 2BaCuO 5 (Y211) contents on the size and morphology of silver particles in YBa 2Cu 3O 7− x (Y123) crystal was investigated. In the samples with an Ag 2O content lower than 10 wt.%, which means a small volume fraction of Ag-rich liquid (L2) in the Ba–Cu rich liquid (L1), most of the silver particles are smaller than 10 μm, and the number of particles larger than 10 μm is small. Increase in the Ag 2O content leads to increase in the number of larger silver particles. This difference in the size distribution is attributed to the manner of separation of Ag which is ejected from the growing Y123 interface. When the ejected Ag is newly separated from the L1 liquid, which will be dominant in the samples with smaller Ag 2O content, these droplets will be small in size because they should exist in the space among the fine Y211 particles. On the other hand, the number of small particles decreases in the sample with larger Ag 2O contents, since large silver particles, many of which are observed within pores, absorb the ejected Ag solute.