Xuyao Zhang

Size-dependent Curie transition of Ni nanocrystals

The mechanical spectroscopy and magnetization measurements are performed on Ni nanocrystals from room temperature to 650 K. It is found that the peak temperatures of internal friction are in agreement with the corresponding Curie temperatures of Ni nanocrystals obtained from the magnetization-temperature curves, showing that the traditional mechanical spectroscopy can also be employed to investigate the Curie transition of ferromagnetic nanocrystals. Moreover, the analytical model for size-dependent Curie temperature is proposed in terms of a size-dependent melting temperature model. The Curie temperature drops with decreasing grain size in Ni nanocrystals, which agrees with the corresponding experimental results.

Temperature-dependent longitudinal tensile strength model for short-fiber-reinforced polymer composites considering fiber orientation and fiber length distribution

In this study, a temperature-dependent longitudinal tensile strength model for short-fiber-reinforced polymer composites (SFRPCs) is established based on the sensitivities of thermal-physical properties of polymer materials to temperature and our previous work. The effects of temperature, fiber orientation distribution, fiber length distribution and residual thermal stress are considered in this model. The theoretical model is verified by comparison with tensile strength of glass SFRPCs at different temperatures. Good agreement between the model predictions and experimental results is obtained, which indicates the reasonability of the proposed models. Furthermore, the comparisons between the present models and the classical models are discussed, and the influencing factors analysis for SFRPCs is also conducted in detail. This study can not only provide a potential convenient means for predicting the temperature-dependent tensile strength of SFRPCs, but also offer useful suggestions for the material evaluation, strengthening and design.

Temperature-dependent critical resolved shear stress model for (Cu–Au)–Co alloys in pure shear mode

Abstract Based on a limited energy storage viewpoint proposed by our team, it is assumed that there is a maximum constant value for the maximum storage of energy per unit volume when dislocation slip starts in a metal. A temperature-dependent critical resolved shear stress (CRSS) model without any fitting parameters is developed for metals in a pure shear mode. The CRSSs of Cu, Cu–Au, Cu–Co and Cu–Au–Co in the pure shear mode are predicted, and are in excellent agreement with the experimental results. This work offers an approach to predict the temperature-dependent CRSS for metals in the pure shear mode.

Effects of temperature and redshift on the refractive index of semiconductors

A theoretical model is developed to study the effect of temperature on the refractive index of semiconductors. The model can be used to predict the refractive index at temperatures ranging from near absolute zero to high temperatures. The theoretical results at wavelengths far from the band-edge region agree well with the available experimental results. In the near-band-edge region, the redshift is found to have an obvious effect on the refractive index at elevated temperatures, and a method is provided for considering this effect. Further verification of the model considering the redshift is included and is consistent with the available experimental results. This theoretical method for prediction of temperature-dependent refractive indices of semiconductors may be helpful in the design of the optical devices.A theoretical model is developed to study the effect of temperature on the refractive index of semiconductors. The model can be used to predict the refractive index at temperatures ranging from near absolute zero to high temperatures. The theoretical results at wavelengths far from the band-edge region agree well with the available experimental results. In the near-band-edge region, the redshift is found to have an obvious effect on the refractive index at elevated temperatures, and a method is provided for considering this effect. Further verification of the model considering the redshift is included and is consistent with the available experimental results. This theoretical method for prediction of temperature-dependent refractive indices of semiconductors may be helpful in the design of the optical devices.