Phase decomposition of single crystals annealed in vacuum

Abstract

The phase decomposition in high-quality (Bi2212) single crystals annealed in vacuum at temperatures 350 - 650 is studied by x-ray diffraction. It is found that the phase of the as-grown single crystals readily decomposes even at temperature as low at 400 in vacuum. With the annealing temperature increasing, is the first phase segregated from the vacuum-annealed single crystals, followed by phases of , oxide and (Bi2201) dependent on temperature. All the segregated phases are highly textured, as observed by using x-ray -scan rocking curves. The phase decomposition occurred at lower temperature and was more dramatic and complicated in vacuum-annealed single crystals than that in air-annealed single crystals reported previously and a possible reason for this is discussed.