PHASE FLUCTUATION OF Pr AND Ca DOPED YBa2Cu3O7−δ COMPOUNDS IN A MICROSCOPIC AREA

Abstract

Experimental investigations have been made on the compound Y 1−x Pr x Ba 2 Cu 3 O 7−δ with increasing praseodymium concentration x. 'Internal temperature gradient' in a muffle furnace would suffice to induce a small-scale melt texture growth to proceed, resulting in a single crystal block with (relatively) regular shape. The ingredients of the materials in the such crystal block, though randomly oriented and sometimes irregular in shape, can be investigated in a systematic way by using techniques such as energy dispersive X-ray analysis. The phase amounts along the crystal layers have been correlated with atomic percentages based on simple, plausible assumptions. This provides us sensible and useful clues to understand the compositions of various samples. Besides, the physical nature of this material has been studied and discussed. Various theoretical models, including the magnetic pair-breaking mechanism and the hole-filling mechanism, were compared with the obtained results.