With the rapid development of micro/nano manufacturing technology and nanomaterials,the accurate measurement of the mechanical properties and behaviors at the micro-nano scale represents a new field of mechanical experiments.Raman spectroscopy,which is based on lattice dynamics theory,is applicable to the detection of the statistical information of the lattice structure deformation within the measuring points.Due to its peculiarities,such as non-destructiveness,convenience and high-resolution,this technology allows the on-line in situ measurement of residual stress in microstructures caused by processing and can also achieve the real-time deformation of graphene,carbon nanotubes and other nanomaterials under force loading.In recent years,mechanical measurements based on Raman spectroscopy technology have developed rapidly.In this review,Raman-based stress measurement theories for several commonly used materials are briefly described.Applications related to the residual stress measurements of microstructure and experimental investigations of the mechanical properties of low-dimensional nanomaterials are then reviewed.Finally,the development trend of this method is proposed.
Magnetic Fe_3O_4@PANI@Au nanocomposites are fabricated through electrostatic self-assembly and seed growth methods.The rate constant K_(app) is calculated to be 8.63×10^(-3) s^(-1) at room temperature for the reduction of 4-nitrophenol to 4-aminophenol with an excessive amount of NaBH_4 as a model system showing outstanding catalytic efficiency and stability.For recyclable performance,the catalyst exhibits slight loss in catalytic performance on the conversion of 4-nitrophenol after running for more than 10 cycles.Besides,the smaller and simpler the structure,the easier the molecular structure can be degraded,and the faster the cationic dyes can be degraded than the anionic dyes,which can reveal the selectivity.For practical application,Congo red as a pollutant of the lake water is degraded rapidly after Fe_3O_4@PANI@Au is added to the solution in a few minutes.It has been demonstrated that magnetic Fe_3O_4@PANI@Au nanoparticle composite is a promising catalyst for environment sewage.
Si-based multilayer structures are widely used in current microelectronics. During their preparation, some inhomogeneous residual stress is induced, resulting in competition between interface mismatching and surface energy and even leading to structure failure. This work presents a methodological study on the measurement of residual stress in a multi-layer semiconductor heterostructure. Scanning electron microscopy(SEM), micro-Raman spectroscopy(MRS), and transmission electron microscopy(TEM) were applied to measure the geometric parameters of the multilayer structure. The relationship between the Raman spectrum and the stress/strain on the [100] and [110] crystal orientations was determined to enable surface and crosssection residual stress analyses, respectively. Based on the Raman mapping results, the distribution of residual stress along the depth of the multi-layer heterostructure was successfully obtained.
