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Abstract: Ge–Sb–Te alloys have played a critical role in present nonvolatile optical and electrical storages. It is generally accepted that their “data encoding” (i.e. amorphization) needs the crystal melting and subsequent quenching. Therefore, liquid should be an important intermediate state during the storage. In this study, based on first-principles molecular dynamics we compared the structural properties of liquid Ge–Sb–Te alloys with three compositions: Ge1Sb2Te4, Ge2Sb2Te5, and Ge4Sb1Te5. In long timescale mean square displacements (MSD), we observe that the element coupled state for Ge1Sb2Te4 and Ge2Sb2Te5 is significantly better than that of Ge4Sb1Te5. The careful analyses by pair correlation functions (PCF) and compositional disorder numbers (CDN) show that Ge2Sb2Te5 has the best stability among the three liquids. Bond angle distributions (BAD) further reflect that all the three liquids essentially retain the crystalline character of local structure with 90˚ bond angle. The present results are helpful to understand the rapid storage technique based on Ge–Sb–Te alloys. [Copyright &y& Elsevier]

We report on the fabrication of a NO 2 gas sensor from room-temperature reduction of graphene oxide(GO) via two-beam-laser interference (TBLI). The method of TBLI gives the distribution of periodic dissociation energies for oxygen functional groups, which are capable to reduce the graphene oxide to hierarchical graphene nanostructures, which holds great promise for gaseous molecular adsorption. The fabricated reduced graphene oxide(RGO) sensor enhanced sensing response in NO 2 and accelerated response/recovery rates. It is seen that, for 20 ppm NO 2 , the response (R a /R g ) of the sensor based on RGO hierarchical nanostructures is 1.27, which is higher than that of GO (1.06) and thermal reduced RGO (1.04). The response time and recovery time of the sensor based on laser reduced RGO are 10 s and 7 s, which are much shorter than those of GO (34 s and 45 s), indicating that the sensing performances for NO 2 sensor at room temperature have been enhanced by introduction of nanostructures. This mask-free and large-area approach to the production of hierarchical graphene micro-nanostructures, could lead to the implementation of future graphene-based sensors.