**3.2 Composition and thermal properties of Field's alloy nanoparticles**

The composition of bulk Field's alloy pellet and the synthesized Field's alloy nanoparticles was deduced with XRF spectrum, which was measured and collected from a mini-X system that uses a mini X-ray tube (Amptek, 40 kV, 100 μA) and a solid state X-ray spectrometer detector (Amptek 123, reflection mode). The whole setup was enclosed in a lead containing acrylic chamber with 1 mm of lead equivalent thickness to make sure no X-ray comes out. As shown in **Figure 3A**, no obvious difference is observed between the composition of the bulk Field's alloy materials and the as-prepared nanoparticles, in which Lα1, Kα1, and Kα2 of indium at 3.29,

**Figure 2.**

*TEM images of Field's alloy particles synthesized at 180°C for 10 min (A) and 2 h (B) using nanoemulsification method; Field's alloy particles size versus reaction temperature for 2 h (C).*

### **Figure 3.**

*X-ray fluorescence spectrum of bulk Field's alloy (black) and nanoparticles (red) (A); DSC curves of Field's alloy nanoparticles synthesized at different temperatures (50, 70, 100, 150, 180°C) for 2–20 h, respectively (B).*

**111**

**Figure 4.**

*Synthesis, Properties, and Characterization of Field's Alloy Nanoparticles and Its Slurry*

**3.3 Thermal stability of Field's alloy nanoparticles and slurry**

24.21, and 27.27 keV; Lα1 and Lβ1 of bismuth at 10.84 and 13.02 keV; and Kα1 of tin at 25.27 keV can be seen clearly. It indicated that no phase separation happens during

DSC was used to measure the thermal properties of as-prepared nanoparticles. **Figure 3B** showed the DSC curves of bulk Field's alloy pellets and corresponding nanoparticles synthesized at different temperatures (50, 70, 100, 150, and 180°C) with other experimental conditions unchanged. For melting peaks of those samples, the peak position and shape were close and similar to the bulk material, where all of the samples are melt at about 62.5°C. However, for freezing peaks, it showed different characteristics for those nanoparticles synthesized at different temperatures. As the temperature increases, the freezing peak position would decrease and became more and more broaden. For example, the bulk Field's alloy was freezing at 55.2°C, and the nanoparticles synthesized at 50°C for 2 h, 70°C for 2 h, 100°C for 2 h, 150°C for 2 h, 180°C for 2 h, and 180°C for 20 h are at 55.2, 53.9, 52.5, 43.4, 32.6, and 32.6°C, respectively. Comparing the DSC curves of those samples under different temperatures, the reaction temperature-dependent freezing depressing

The thermal properties of Field's alloy slurry were investigated using a DSC. As shown in **Figure 4A**, the slurry can undergo melting-freezing phase transition during heating and cooling scanning processes. The downward endothermic peak at 62.5°C was belonging to the melting of the Field's alloy nanoparticles, while the upward

*Cyclic DSC curves of Field's alloy nanoparticles in ambient and nitrogen atmosphere, respectively (A); cyclic DSC curves of Field's nanoparticles after running in ambient condition for 1st, 5th, 10th, 15th, and 20th times, respectively (B); cyclic DSC curves of the slurry in ambient and nitrogen atmosphere (C); cyclic DSC curves of the slurry after running for 1st, 5th, 10th, 15th, and 20th times in ambient condition, respectively (D).*

*DOI: http://dx.doi.org/10.5772/intechopen.84224*

the whole synthesis process.

was observed.

*Synthesis, Properties, and Characterization of Field's Alloy Nanoparticles and Its Slurry DOI: http://dx.doi.org/10.5772/intechopen.84224*

24.21, and 27.27 keV; Lα1 and Lβ1 of bismuth at 10.84 and 13.02 keV; and Kα1 of tin at 25.27 keV can be seen clearly. It indicated that no phase separation happens during the whole synthesis process.

DSC was used to measure the thermal properties of as-prepared nanoparticles. **Figure 3B** showed the DSC curves of bulk Field's alloy pellets and corresponding nanoparticles synthesized at different temperatures (50, 70, 100, 150, and 180°C) with other experimental conditions unchanged. For melting peaks of those samples, the peak position and shape were close and similar to the bulk material, where all of the samples are melt at about 62.5°C. However, for freezing peaks, it showed different characteristics for those nanoparticles synthesized at different temperatures. As the temperature increases, the freezing peak position would decrease and became more and more broaden. For example, the bulk Field's alloy was freezing at 55.2°C, and the nanoparticles synthesized at 50°C for 2 h, 70°C for 2 h, 100°C for 2 h, 150°C for 2 h, 180°C for 2 h, and 180°C for 20 h are at 55.2, 53.9, 52.5, 43.4, 32.6, and 32.6°C, respectively. Comparing the DSC curves of those samples under different temperatures, the reaction temperature-dependent freezing depressing was observed.

### **3.3 Thermal stability of Field's alloy nanoparticles and slurry**

The thermal properties of Field's alloy slurry were investigated using a DSC. As shown in **Figure 4A**, the slurry can undergo melting-freezing phase transition during heating and cooling scanning processes. The downward endothermic peak at 62.5°C was belonging to the melting of the Field's alloy nanoparticles, while the upward

#### **Figure 4.**

*Nanoemulsions - Properties, Fabrications and Applications*

was still close to 20 nm.

**3.1 Size and morphologies of Field's alloy nanoparticles**

The size and morphologies of synthesized Field's alloy nanoparticles using nanoemulsion method were investigated by TEM. **Figure 2** showed the TEM images of the as-prepared Field's alloy particles after boiling the Field's alloy pellets in PAO at 180°C for 10 min (**Figure 2A**) and 2 h (**Figure 2B**), respectively. When the boiling time increases, the size of particles would decrease and became more and more spherical. After 10 min, the particles have irregular shapes and with the size range from 200 to 500 nm. As the time increases to 2 hours, the particles showed spherical shapes with the size of about 20 nm. **Figure 2C** showed the plot of reaction time versus the size of particles. After 2 hours, even though the reaction time increase (such as 5, 10, or even 20 h), the particles size did not have too much change, which

**3.2 Composition and thermal properties of Field's alloy nanoparticles**

The composition of bulk Field's alloy pellet and the synthesized Field's alloy nanoparticles was deduced with XRF spectrum, which was measured and collected from a mini-X system that uses a mini X-ray tube (Amptek, 40 kV, 100 μA) and a solid state X-ray spectrometer detector (Amptek 123, reflection mode). The whole setup was enclosed in a lead containing acrylic chamber with 1 mm of lead equivalent thickness to make sure no X-ray comes out. As shown in **Figure 3A**, no obvious difference is observed between the composition of the bulk Field's alloy materials and the as-prepared nanoparticles, in which Lα1, Kα1, and Kα2 of indium at 3.29,

**110**

**Figure 3.**

**Figure 2.**

*X-ray fluorescence spectrum of bulk Field's alloy (black) and nanoparticles (red) (A); DSC curves of Field's alloy nanoparticles synthesized at different temperatures (50, 70, 100, 150, 180°C) for 2–20 h, respectively (B).*

*TEM images of Field's alloy particles synthesized at 180°C for 10 min (A) and 2 h (B) using nanoemulsification* 

*method; Field's alloy particles size versus reaction temperature for 2 h (C).*

*Cyclic DSC curves of Field's alloy nanoparticles in ambient and nitrogen atmosphere, respectively (A); cyclic DSC curves of Field's nanoparticles after running in ambient condition for 1st, 5th, 10th, 15th, and 20th times, respectively (B); cyclic DSC curves of the slurry in ambient and nitrogen atmosphere (C); cyclic DSC curves of the slurry after running for 1st, 5th, 10th, 15th, and 20th times in ambient condition, respectively (D).*

exothermic peak at 35.5°C was for their freezing. This observed melting-freezing temperature difference (about 27°C), called supercooling, had been well explained by the classical nucleation theory [39]. As shown in **Figure 4B**, no obvious changes of the slurry after running for 20 cycles, it suggested that slurry was very stable in ambient condition. It suggested that the nanoparticles are stable in ambient condition. As shown in **Figure 4C**, the nano-PCM slurry can undergo melting-freezing phase transition during heating and cooling scanning processes. The downward endothermic peak at 62.5°C was belonging to the melting of the Field's alloy nanoparticles, while the upward exothermic peak at 35.5°C was for their freezing. As shown in **Figure 4D**, no obvious changes of the nano-PCM slurry after running for 20 cycles, it suggested that nano-PCM slurry is very stable in the temperature range under 100°C.
