High-Pressure Behaviors of Ag(2)S Nanosheets: An in Situ High-Pressure X-Ray Diffraction Research

An in situ high-pressure X-ray diffraction study was performed on Ag(2)S nanosheets, with an average lateral size of 29 nm and a relatively thin thickness. Based on the experimental data, we demonstrated that under high pressure, the samples experienced two different high-pressure structural phase transitions up to 29.4 GPa: from monoclinic P2(1)/n structure (phase I, α-Ag(2)S) to orthorhombic P2(1)2(1)2(1) structure (phase II) at 8.9 GPa and then to monoclinic P2(1)/n structure (phase III) at 12.4 GPa. The critical phase transition pressures for phase II and phase III are approximately 2–3 GPa higher than that of 30 nm Ag(2)S nanoparticles and bulk materials. Additionally, phase III was stable up to the highest pressure of 29.4 GPa. Bulk moduli of Ag(2)S nanosheets were obtained as 73(6) GPa for phase I and 141(4) GPa for phase III, which indicate that the samples are more difficult to compress than their bulk counterparts and some other reported Ag(2)S nanoparticles. Further analysis suggested that the nanosize effect arising from the smaller thickness of Ag(2)S nanosheets restricts the relative position slip of the interlayer atoms during the compression, which leads to the enhancing of phase stabilities and the elevating of bulk moduli.