I. Bryntse et A. Kareiva, SUPERCONDUCTIVITY IN HGBA2CA2CU3O8- SYNTHESIZED BY DIFFERENT METHODS(DELTA ), Materials research bulletin, 30(10), 1995, pp. 1207-1216
The composition and superconducting properties of powder samples of Hg
-1223, HgBa2Ca2Cu3O8+delta, were investigated. The specimens were prep
ared by a single-step method using individual metal oxides, and by a t
wo-step method in which the precursor Ba2Ca2Cu3O7+delta was first synt
hesized by sol-gel method and then mixed with HgO. The final annealing
was performed in sealed quartz ampoules at 665 degrees C or 860 degre
es C, and the purity of the obtained samples was compared. After oxyge
n treatment at 300 degrees C for 6 h the samples showed superconductiv
ity at a T-C(onset) of approximately 134 K, as determined from AC susc
eptibility measurements. The materials were also studied by X-ray powd
er diffraction and scanning and transmission electron microscopy.