Relation between size and phase structure of gallium: Differential scanning calorimeter experiments

Abstract

The relation between sizes and phase structures of gallium has been studied. Gallium droplets with different sizes dispersed in poly͑methyl methacrylate͒ and silicone oil were studied by differential scanning calorimeter and transmission electron microscopy. The results showed that particles with different sizes corresponded to stable or metastable phases of gallium. The stable phase ␣-gallium is dominantly formed when the average size of particles is no less than 0.8 micron, and the metastable phases ␤-, ␥-and ␦-gallium are mainly formed when the average particle size is 0.8-0.6 micron, 0.6-0.3 micron, and below 0.3 micron, respectively. The phase selection in the solidification process under undercooling is used to explain the results.

Melting behavior of confined Ga particles studied by internal friction

“…In Fig. 6, the heating measurement DSC trace of Ga/PMMA sample with a scanning rate of 20 • C/min was shown, and there are four endothermal peaks, which are attributed to the melting of α-, β-, δ-, and γ -phases of Ga particles, as has been reported before [16]. By comparing Figs.…”

“…3). It has been proved that the phase structures are closely related with sizes of Ga particles [16]. The stable phase α-Ga, is dominantly formed when the average size of Ga particles is no less than 0.8 micron, and the metastable phases β-, γ -and δ-Ga are mainly formed when the average particle size is below 0.8 micron.…”

“…Ga is a unique system which has four orthorhombic crystalline structural phases, α-, β-, δ-and γ -phases with respective melting points of 29.9 • C, −16.2 • C, −19.4 • C and −35.6 • C. In these phases, only α is a stable phase, and all others are metastable ones. The physical property of Ga has been studied widely [16][17][18]. In this study, Ga particles with a gradient size distribution were dispersed in poly(methyl methacrylate) (PMMA) matrix by means of ultrasonic vibration and sedimentation method, and the melting behavior of confined Ga particles was studied by DMA.…”

Solid‐state formation of ferromagnetic δ‐Mn0.6Ga0.4 thin films with high rotatable uniaxial anisotropy

“…1a) contained weak responses for α‐Mn and metastable β‐Ga phase. The formation of the β‐Ga phase and other metastable polymorphous modifications of Ga are related to undercooling phenomena 25 or size effect 26. After annealing at 300 °C, the responses from Ga and Mn vanished and features corresponding to a cubic ϕ‐Ga 7.7 Mn 2.3 phase developed (Fig.…”

Cluster melting: new, limiting, and liminal phenomena

“…120 GPa), after passing through several other phases, gallium does eventually adopt the same FCC structure as aluminium [72]. Intriguingly, experimental investigations suggest that the standard phase of gallium clusters is not known at all in the submicron regime (below approximately 0.8 µm) [73,74] (with of course the previously mentioned exception of the smallest molecular sizes [71]). …”