With the progress of modern transmission elec- tron microscopy （TEM） and development of dedicated func- tional TEM specimen holders, people can now manipulate a nano-object with nanometer-range precision and simulta- neously acquire mechanical data together with atomic-scale structural information. This advanced methodology is play- ing an increasingly important role in nanomechanics. The present review summarizes relevant studies on the in situ in- vestigation of mechanical properties of various nanomateri- als over the past decades. These works enrich our knowledge not only on nanomaterials （such as carbon nanotubes, car- bon onions, boron nitride nanotubes, silicon nanowires and graphene, etc.） but also on mechanics at the nanoscate.
Sb rich Ge_(2)Sb_(5)Te_(5) materials are investigated for use as the storage medium for high-speed phase change memory(PCM).Compared with conventional Ge2Sb2Te5,Ge_(2)Sb_(5)Te_(5) films have a higher crystallisation temperature(~200℃),larger crystallisation activation energy(3.13 eV),and a better data retention ability(100.2℃ for ten years).A reversible switching between set and reset states can be realised by an electric pulse as short as 5 ns for Ge_(2)Sb_(5)Te_(5)-based PCM cells,over 10 times faster than the Ge_(2)Sb_(5)Te_(5)-based one.In addition,Ge2Sb2Te5 shows a good endurance up to 3×10^(6) cycles with a resistance ratio of about three orders of magnitude.This work clearly reveals the highly promising potential of Ge_(2)Sb_(5)Te_(5) films for applications in high-speed PCM.
