U-Pt-Sm-Ba-O chemical pinning centers in Ag-doped Sm123 textured in reduced oxygen

In the U/n process enriched uranium is admixed to HTS powders, textured and then irradiated with thermal neutrons. Neutrons must penetrate several centimeters for such processing to be successful in textured materials. Bulk Sm123 cannot be U/n processed because thermal neutrons penetrate <1 mm. However, textured Sm123 can still benefit from chemical pinning centers that are formed during U/n processing. Thin or thick films of Sm123 can still be successfully U/n processed. In the present work, powders containing Ag₂O + 20 mol% Sm211 + Sm123 + Pt are doped with depleted U, and textured in a 1% oxygen atmosphere. Microstructure studies indicate the presence of small deposits of (U_0.5Pt_0.5)SmBa₂O₆, which are double perovskites. Important characteristics of the U-Pt-Sm-Ba-O particles are: (a) average size is 500 nm, (b) distribution is fairly uniform within the Sm123, (c) the number of deposits is proportional to the mass of admixed U (i.e., size is constant for increasing doping levels) (d) U does not substitute into the background Sm123, (e) Ag does not interact with either U or Pt, and (f) there is less coarsening of the U-rich particles when the dwell time of the maximum temperature in the temperature versus time profile is <2 hours. The U-Pt-Sm-Ba-O deposits are strikingly similar to the U-Pt-Y-Ba-O deposits found earlier in U-doped Y123. Tungsten or molybdenum can be used as nonradioactive substitutes for uranium to produce similar double perovskites deposits.