Laser ultrasound characterization of chemically prepared nano-structured silver

The ultrasonic properties of nano-structured silver (hereafter nm-Ag) are investigated by the laser ultrasonic technique. The nm-Ag superfine particles with a size of 20 to 27 nanometer (nm) are prepared by using a chemical method. Wafers of nm-Ag are fabricated under different pressing pressures and used as samples. The experimental results show that the ultrasonic velocity and attenuation of nm-Ag prepared by the chemical method depends on the pressing pressures and thus on the relative density. The elastic moduli values of nm-Ag prepared by the chemical method are deduced. The values are lower than those of polycrystalline and single-crystalline Ag. The detailed results, discussions, and comparisons with nm-Ag samples prepared by a physical method are presented.