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Highlights: [•] Molecular dynamics simulation was performed to study the deformation behaviors of Zigzag Graphene Nano-Ribbons (ZGNRs). [•] The “phase transformation” from hexagonal to quasi-rectangular and the subsequent second elastic deformation were observed. [•] Related thermal effects model was built to predict fracture strain of ZGNRs, and was consistent with simulation results. [ABSTRACT FROM AUTHOR]

The temperature dependence of the crystal structure for Bi1−2.5 x Pr1.5 x Ba x FeO3 (x =0.05, 0.1) polycrystallines is studied by X-ray powder diffraction with Rietveld refinements in the temperature range of 25–800°C. A structural phase transition of Rhombohedral-to-Cubic occurs for Bi0.875Pr0.075Ba0.05FeO3 sample in the temperature of 600–700°C, which may relate to its unstable rhombohedra distorted structure with the space group R3c. The rarely decomposition of these samples indicates that the Pr, Ba co-doped make the BiFeO3 ceramics more stable. The thermal expansion determined by the temperature dependence of the unit-cell lattice parameters and volumes for Bi1−2.5 x Pr1.5 x Ba x FeO3 samples is also investigated, which shows an isotropic and positive behavior. The average thermal expansion coefficient decreases with the increasing x. We argue that the Cubic crystal structure with the high symmetrical of the space group Pm3m may be more stable for Bi0.75Pr0.15Ba0.1FeO3 sample, which may explain the reason why no phase transition occurs and its lower thermal expansion efficiencies. An obvious change in the slope of the linear fitted lines between 300°C and 400°C suggests a possible antiferromagnetic–paramagnetic transition, which occurs around the Néel temperature of the Bi1−2.5 x Pr1.5 x Ba x FeO3 samples. [ABSTRACT FROM AUTHOR]

The effects of Cu concentration ( x ) on the interfacial microstructure between a molten Sn-3Ag- x Cu alloy and an electrolytic Au/Ni/Cu multilayer and its mechanical reliability were investigated via transmission electron microscopy (TEM) and high-speed ball shear (HSBS) testing. The x values were 0, 0.3, 0.4, 0.5, 0.7, and 1.0 (wt%). An increase in x caused an interfacial intermetallic compound (IMC) transition from a dense (Ni,Cu) 3 Sn 4 layer ( x = 0 and 0.3) to the coexistence of (Ni,Cu) 3 Sn 4 and (Cu,Ni) 6 Sn 5 ( x = 0.4 and 0.5), and to a dense (Cu,Ni) 6 Sn 5 layer ( x = 0.7 and 1.0) after soldering reaction at 250 °C for 2 min. An increase in the reaction time enhanced the IMC growth and induced the nucleation of a (Ni,Cu) 3 Sn 4 nanolayer beneath (Cu,Ni) 6 Sn 5 in the high x case. The TEM and HSBS characterizations showed that a single, thin (Ni,Cu) 3 Sn 4 layer grown at the interface possessed better shear resistance than a single (Cu,Ni) 6 Sn 5 layer, and the presence of a dual layer structure of (Cu,Ni) 6 Sn 5 /(Ni,Cu) 3 Sn 4 substantially degraded the mechanical properties of the joint interface. These observations indicated that the Cu concentration in Sn-3Ag- x Cu alloy plays a crucial role in the interfacial reaction, which, in turn, dominates the mechanical reliability of microelectronic joints. [ABSTRACT FROM AUTHOR]