Processing of Ag-doped Bi2212 bulks in high magnetic fields: a strong correlation between degree of texture and field strength

A series of high magnetic fields up to 9 T have been applied to the preparation of Ag-doped Bi2212 bulks and a strong correlation is observed between the field strength and the degree of texture developed in the bulks. Two powders of Bi_2.2Sr_1.8CuO_x and CaCuO₂ were synthesized separately and then 10 wt.% Ag was doped to their equimolar mixture, from which the Bi2212 bulks were formed by a partial melt-solidification process in the high magnetic fields. The degree of texture in the bulks was evaluated quantitatively by X-ray diffraction and magnetization measurement. It is found that the applied magnetic fields tend to orient Bi2212 grains with their c-axis parallel to them and obvious texture exists in all samples prepared in the magnetic fields; while in samples prepared without magnetic field Bi2212 grains orient randomly. In the field range of 0-9 T, the degree of texture increases notably with increasing the magnetic field. In 9 T Bi2212, bulks with magnetization anisotropy factor more than four and a density of 6.15 g/cm³ are obtained and SEM observation also shows a highly oriented grain alignment.