Process for preparing mercury-barium-calcium-copper-oxide-based superconductor materials

A process for preparing a superconductor, said process comprising the steps of:

• mixing a first member of a series of superconductors comprising mercury, barium, copper and oxygen;
• a source of calcium;
• a source of copper;
• and a source of rhenium to form a precursor mixture;
• the atomic ratio of mercury to rhenium in the precursor mixture being greater than about 3:1;
• and
• annealing the precursor mixture to form a second member of the series of superconductors comprising mercury, barium, copper and oxygen;
• said source of calcium and said source of copper being provided so as to maintain the approximate stoichiometry of the second member of the series of superconductors prepared from the precursor mixture;
• and
• said second member having a larger atomic ratio of calcium to barium than said first member.

A process for preparing a superconductor having the formula (Hg.sub.1-(x+z),Re.sub.x,D.sub.z)Ba.sub.2 Ca.sub.2 Cu.sub.3 O.sub.8-y, wherein Re is rhenium;

• D is an element selected from the group consisting of halogens and metals other than mercury, barium, calcium, copper and rhenium;
• x ranges from 0 to about 0.25;
• z ranges from 0 to about 0.25;
• and y is a rational number between about negative 1 to about positive 1, said process comprising the steps of:
• mixing a first member of a series of superconductors comprising mercury, barium, copper and oxygen;
• a source of calcium;
• and a source of copper to form a precursor mixture;
• and
• annealing the precursor mixture to form a second member of the series of superconductors comprising mercury, barium, copper and oxygen;
• wherein the first member has the formula (Hg.sub.1-(x+z),Re.sub.x,D.sub.z)Ba.sub.2 Ca.sub.1 Cu.sub.2 O.sub.6-y ;
• Re is rhenium;
• D is an element selected from the group consisting of halogens and metals other than mercury, barium, calcium, copper and rhenium;
• x ranges from 0 to about 0.25;
• z ranges from 0 to about 0.25;
• and y is a rational number between about negative 1 to about positive 1;
• said source of calcium and said source of copper being provided so as to maintain the approximate stoichiometry of the second member of the series of superconductors prepared from the precursor mixture;
• and
• said second member having a larger atomic ratio of calcium to barium than said first member.