Properties of 50 nm electroless films Ag-W-oxygen before and after low temperature, low activation energy resistivity decay

50 nm films Ag-(0.3-1 at.% W)-oxygen deposited by electroless onto Pd activated SiO₂/Si show fast, low activation energy decay of their electrical resistivity ρ after annealing above the threshold temperature T^* = 90 ± 10 °C. The decrease in ρ was attributed in our previous works to surface diffusion controlled sintering. In attempt to understand the mechanism of this interesting effect we studied further the origin of open porosity, W segregation, evolution of the tungstate phase Ag₂W₂O₇ at the internal interfaces and temporal evolution of surface roughness in the course of annealing. A possible role of the tungstate phase transition to super ion conductive state in the diffusion mobility of Ag is speculated.