Resistivity hysteresis of Ag2S nanocomposites

A low-temperature chemical synthesis route was used to prepare Ag2S particles with diameters ranging from 3 to 39 nm within a silica matrix. The dc electrical resistivity was measured in the temperature range of 320-460 K. A drastic reduction in resistivity around 450 K was caused by an order-disorder transition of Ag2S. The specimens exhibited a hysteresis in resistivity as a function of temperature. The width of the hysteresis was related to the particle size, viz., it increased with an increase in particle size. This is believed to arise due to a reduction in interfacial free energy for crystal formation in the cation sublattice for smaller Ag2S particle sizes.