Unstrained and compressive-strained Ge1−xSnx alloys were grown on InGaAs buffer layers by molecular beam epitaxy. Photoreflectance at room temperature determines the direct bandgap energies of Ge1−xSnx alloys from the maxima of the light- and heavy-hole bands to the bottom of Γ valley. The lowest transition energies from photoreflectance are consistent with the energies derived from photoluminescence. The calculated bowing parameter is 2.42 ± 0.04 eV for the direct band gap of Ge1−xSnx alloys. The dilational and shear deformation potentials of the direct band gap are −11.04 ± 1.41 eV and −4.07 ± 0.91 eV, respectively. These basic material parameters are important in designing optoelectronic devices based on Ge1−xSnx alloys.

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SixGe1−x−ySny alloys were grown by molecular beam epitaxy at low temperature, followed by ex-situ annealing. The crystal quality of SixGe1−x−ySny layers was characterized by atomic force microscopy and transmission electron microscopy. The compositions and lattice constants of the alloys were studied by x-ray photoelectron spectroscopy and x-ray diffraction. The results show that Vegard’s law is a good approximation for SixGe1−x−ySny alloys. Photoreflectance spectroscopy at room temperature was used to determine the direct bandgap energy of SixGe1−x−ySny layers. Analyzing the relationship between composition and direct bandgap energy reveals a negative energy bowing parameter for SiSn.

Peridynamics theory is a nonlocal meshless method that replaces differential equations with spatial integral equations, and has shown good applicability and reliability in the analysis of discontinuities. Further, with characteristics of clear physical meaning and simple and reliable numerical calculation, the bond-based peridynamics method has been widely applied in the field. However, this method describes the interaction between material points simply using a single elastic “spring”, and thus leads to a fixed Poisson’s ratio, relatively low computational efficiency and other inherent problems. As such, the goal of this review paper is to provide a summary of the various methods of bond-based peridynamics modeling, particularly those that have overcome the limitations of the Poisson’s ratio, considered the shear deformation and modeling of two-dimensional thin plates for bending and three-dimensional anisotropic composites, as well as explored coupling with finite element methods. This review will determine the advantages and disadvantages of such methods and serve as a starting point for researchers in the development of peridynamics theory.

When using nanoindentation to measure the mechanical properties of biological tissues, viscoelastic effects may be significant and may affect the accuracy of the results. In this study, a method for correcting viscoelastic effects during nanoindentation is described. The correction formula involved is re-derived using a three-element nonlinear visco-plasto-elastic material tensor model. This method is then applied to forelimb and femur bone samples taken from two species (C57 BL/6N and ICR) of mice. After correcting for viscoelastic effects, elastic modulus and hardness results are found to be independent of experimental conditions, such as the unloading rate. Measured mechanical properties also correlate well with the calcium content of the bone samples.