technique

The diffusion of Ag in superconducting YBa2Cu3O7 ceramic was studied over the temperature range 700-850degreesC by the energy-dispersive X-ray fluorescence (EDXRF) technique. For the excitation of silver atoms, an annular Am-241 radioisotope source (50 mCi) emitting 59.543 keV photons was used. The temperature dependences of Ag diffusion coefficients in grains (D-1) and over the grain boundaries (D-2) are described by the equations D-1 = 1.4 X 10(-2) exp[-(1.18 +/- 0.10)/kT] and D-2 = 3.1 X 10(-4) exp[-(0.87 +/- 0.10)/kT]. Copyright (C) 2003 John Wiley Sons, Ltd