Laser ultrasound characterization of chemically prepared nano-structured silver

The ultrasonic propel ties of nano-structured silver (hereafter nm-Ag) are investigated by the laser ultrasonic technique. The nm-Ag superfine particl es 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 a nd used as samples. The experimental results show that the ultrasonic veloc ity and attenuation of nm-AE prepared by the chemical method depends on the pressing pressures and thus on the relative density. The elastic moduli va lues of nm Ag prepared by the chemical method are deduced. The values are l ower than those of polycrystalline and single-crystalline Ag. The detailed results, discussions, and comparisons with nm-Ag samples prepared by a phys ical method are presented.