Process for preparing a bulk textured superconductive material

A process for preparing a bulk superconductive material, comprising the steps of:

• (a) providing a diffusion couple comprised of a first layer and a second layer integrally connected to each other, wherein:
• i. said second layer is comprised of at least about 50 weight percent of material with a stoichiometry represented by a formula selected from the group consisting of
• (R.sub.1-z M.sub.z) (Ba.sub.2-y M'.sub.y)Cu.sub.3 O.sub.6+x,
• (R.sub.1-z M.sub.z) (Ba.sub.2-y M'.sub.y)Cu.sub.4 O.sub.8,
• (AO).sub.m M".sub.2 Ca.sub.n-1 Cu.sub.n O.sub.2n+2, and mixtures thereof, wherein:
• (a) x is from about 0.5 to 1.0,
• (b) R is selected from the group consisting of yttrium, gadolinium, lanthanum, europium, holmium, dysprosium, scandium, neodymium, thulium, samarium, ytterbium, lutetium, praseodymium, and mixtures thereof,
• (c) M and M' are independently selected from the group consisting of barium, strontium, calcium, yttrium, gadolinium, lanthanum, europium, holmium, dysprosium, scandium, neodymium, thulium, samarium, ytterbium, lutetium, praseodymium, and mixtures thereof, (d) z is from about 0 to about 0.5, and y is from about 0 to about 0.4,
• (e) A is selected from the group consisting of thallium, bismuth, lead, mixtures of thallium and lead, and mixtures of bismuth and lead,
• (f) m is from about 1 to about 3,
• (g) M" is selected from the group consisting of barium, strontium, and mixtures thereof, and
• (h) n is at least 1;
• ii. said first layer is comprised of at least 50 weight percent of a compound selected from the group consisting of bismuth oxide, antimony oxide, arsenic oxide, phosphorous oxide, silicon oxide, tin oxide, copper oxide, boron oxide, indium oxide, thallium oxide, gallium oxide, alumina, yttrium oxide, lanthanum oxide, scandium oxide, praesodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, ytterbium oxide, lutetium oxide, titanium oxide, zirconium oxide, hafnium oxide, niobium oxide, barium cuprate, barium oxide, strontium oxide, calcium oxide, magnesium oxide, beryllium oxide, and mixtures thereof,
• iii. when said diffusion couple is heated to a temperature of least about 800 degrees Centigrade for at least about 10 minutes, said second layer has a shrinkage which is greater than the shrinkage of said first layer;
• (b) raising the temperature of said diffusion couple from ambient temperature to a temperature at least about 1,000 degrees Centigrade at a rate of from about from about 4 to about 7 degrees Centigrade per minute;
• (c) thereafter heating said diffusion couple at said temperature of at least about 1,000 degrees Centigrade for from about 10 to about 120 minutes while contacting said diffusion couple with an oxygen-containing gas flowing over said diffusion couple at a rate of from about 0.5 to about 5.0 liters per minute;
• (d) thereafter cooling said diffusion couple from said temperature of at least about 1,000 degrees Centigrade to a temperature of about 930 degrees Centigrade at a rate of from about 1 to about 10 degrees per hour while contacting said diffusion couple with an oxygen-containing gas flowing over said diffusion couple at a rate of from about 0.5 to about 5.0 liters per minute.