Single-step synthesis of bulk HgBa2Ca2Cu3O8+δ

✍ Scribed by M. Paranthaman

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 400 KB
• Volume: 222
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)90107-4

✦ Synopsis

Bulk superconducting samples of nearly phase-pure HgBa2Ca2CuaOs + 6 (hereafter denoted as Hg-1223 ) were prepared by a solid-state reaction of stoichiometric quantities of HgO, BaO, CaO and CuO in a single step. The starting mixtures were ground, pressed into a pellet, sealed in a quartz tube, and heated to 840-860 ° C. The "as-synthesized" Hg-1223 samples had a Tc of 110-112 K, as defined by the onset of diamagnetism. The crystal symmetry was found to be tetragonal with a space group of P4/ mmm, and lattice parameters a = 3.852 ( 1 ) A and c = 15.830 ( 1 ) A, similar to the values for T1Ba2Ca2Cu309 _ 6-Finely ground powders were stable upon exposure to ambient air for a period of ~ 4 days. On annealing in 1 atm oxygen at 300 ° C for 6 h, these samples gained weight (corresponding to ~ 0.066-0.075 oxygen atoms per formula unit) and displayed sharp superconducting transitions up to 134.5 K. Using this procedure, high-quality Hg-1223 samples can be easily synthesized.