We confirm whether Zr powders can restrain a rapid nitrification reaction and offer a stable oxidation reaction according to temperatures in nitrogen gas purification. A pellet-type, porous Zr getter is prepared (diameter: 10 and thickness: 3 mm) using Zr powder with an average particle size of 45 μm. While maintaining the whole system, the Zr getter reaction is confirmed with an increase in temperature from 150 to 550 oC at increments of 100 oC under 99.999 % purity nitrogen atmosphere comprising of 10 ppm of impurity. Surface color, pore size, stabilized layer, and phase change are confirmed with optical microscopy, SEM-EDS, Micro-Raman, and X-ray diffraction (XRD) according to the Zr getter temperature. The surface color of the Zr getter changes from metallic silver to dark gray as temperature increases. In the EDS results, the nitrogen component is not observed, and oxygen content increases from each surface at elevated temperatures. The Raman and XRD results show the oxidation layer as a result of 350 oC annealing. Therefore, the Zr getter can be applied as a nitrogen getter under 5-nine purity nitrogen atmosphere after appropriate oxidized pre-stabilization process to prevent rapid nitrification reaction.

Dinickel-silicide (Ni2Si)/glass was employed as a counter electrode for a dye-sensitized solar cell (DSSC) device. Ni2Si was formed by rapid thermal annealing (RTA) at 700 oC for 15 seconds of a 50 nm-Ni/50 nm-Si/glass structure. For comparison, Ni2Si on quartz was also prepared through conventional electric furnace annealing (CEA) at 800 oC for 30 minutes. XRD, XPS, and EDS line scanning of TEM were used to confirm the formation of Ni2Si. TEM and CV were employed to confirm the microstructure and catalytic activity. Photovoltaic properties were examined using a solar simulator and potentiostat. XRD, XPS, and EDS line scanning results showed that both CEA and RTA successfully led to tne formation of nano thick- Ni2Si phase. The catalytic activity of CEA-Ni2Si and RTA-Ni2Si with respect to Pt were 68 % and 56 %. Energy conversion efficiencies (ECEs) of DSSCs with CEA-Ni2Si and RTA-Ni2Si catalysts were 3.66 % and 3.16 %, respectively. Our results imply that nano-thick Ni2Si may be used to replace Pt as a reduction catalytic layer for a DSSCs. Moreover, we show that nanothick Ni2Si can be made available on a low-cost glass substrate via the RTA process.

We improve the energy conversion efficiency (ECE) of a dye sensitized solar cell (DSSC) by preparing a working electrode (WE) with localized surface plasmon resonance (LSPR) by inducing Au thin films with thickness of 0.0 to 5.0 nm, deposited via sputtering. Field emission scanning electron microscopy and atomic force microscopy were used to characterize the microstructure of the blocking layer (BL) of the Au thin films. Micro-Raman measurement was employed to confirm the LSPR effect, and a solar simulator and potentiostat were used to evaluate the photovoltaic properties, including the impedance and the I-V of the DSSC of the Au thin films. The results of the microstructural analysis confirmed that nano-sized Au agglomerates were present at certain thicknesses. The photovoltaic results show that the ECE reached a value of 5.34% with a 1-nm thick-Au thin film compared to the value of 5.15 % without the Au thin film. This improvement was a result of the increase in the LSPR of the TiO2 layer that resulted from the Au thin film coating. Our results imply that the ECE of a DSSC may be improved by coating with a proper thickness of Au thin film on the BL.

The cobalt silicides were investigated for employment as a catalytic layer for a DSSC. Using an E-gun evaporation process, we prepared a sample of 100 nm-thick cobalt on a p-type Si (100) wafer. To form cobalt silicides, the samples were annealed at temperatures of 300 oC, 500 oC, and 700 oC for 30 minutes in a vacuum. Four-point probe, XRD, FE-SEM, and CV analyses were used to determine the sheet resistance, phase, microstructure, and catalytic activity of the cobalt silicides. To confirm the corrosion stability, we also checked the microstructure change of the cobalt silicides after dipping into iodide electrolyte. Through the sheet resistance and XRD results, we determined that Co2Si, CoSi, and CoSi2 were formed successfully by annealing at 300 oC, 500 oC, and 700 oC, respectively. The microstructure analysis results showed that all the cobalt silicides were formed uniformly, and CoSi and CoSi2 layers were very stable even after dipping in the iodide electrolyte. The CV result showed that CoSi and CoSi2 exhibit catalytic activities 67 % and 54 % that of Pt. Our results for Co2Si, CoSi, and CoSi2 revealed that CoSi and CoSi2 could be employed as catalyst for a DSSC.

We prepared polymethyl methacrylate (PMMA) beads with a particle size of 80 nm to improve the energy conversion efficiency (ECE) by increasing the effective surface area and the dye absorption ability of the working electrodes (WEs) in a dye sensitized solar cell (DSSC). We prepared the TiO2 layer with PMMA beads of 0.0~1.0 wt%; then, finally, a DSSC with 0.45 cm2 active area was obtained. Optical microscopy, transmission electron microscopy, field emission scanning electron microscopy, and atomic force microscopy were used to characterize the microstructure of the TiO2 layer with PMMA. UV-VIS-NIR was used to determine the optical absorbance of the WEs with PMMA. A solar simulator and a potentiostat were used to determine the photovoltaic properties of the PMMA-added DSSC. Analysis of the microstructure showed that pores of 200 nm were formed by the decomposition of PMMA. Also, root mean square values linearly increased as more PMMA was added. The absorbance in the visible light regime was found to increase as the degree of PMMA dispersion increased. The ECE increased from 4.91% to 5.35% when the amount of PMMA beads added was increased from 0.0 to 0.4 wt%. However, the ECE decreased when more than 0.6 wt% of PMMA was added. Thus, adding a proper amount of PMMA to the TiO2 layer was determined to be an effective method for improving the ECE of a DSSC.

To alloy high melting point elements such as boron, ruthenium, and iridium with copper, heat treatment was performed using metal oxides of B2O3, RuO2, and IrO2 at the temperature of 1200 oC in vacuum for 30 minutes. The microstructure analysis of the alloyed sample was confirmed using an optical microscope and FE-SEM. Hardness and trace element analyses were performed using Vickers hardness and WD-XRF, respectively. Diffusion profile analysis was performed using D-SIMS. From the microstructure analysis results, crystal grains were found to have formed with sizes of 2.97 mm. For the copper alloys formed using metal oxides of B2O3, RuO2, and IrO2 the sizes of the crystal grains were 1.24, 1.77, and 2.23 mm, respectively, while these sizes were smaller than pure copper. From the Vickers hardness results, the hardness of the Ir-copper alloy was found to have increased by a maximum of 2.2 times compared to pure copper. From the trace element analysis, the copper alloy was fabricated with the expected composition. From the diffusion profile analysis results, it can be seen that 0.059 wt%, 0.030 wt%, and 0.114 wt% of B, Ru, and Ir, respectively, were alloyed in the copper, and it led to change the hardness. Therefore, we verified that alloying of high melting point elements is possible at the low temperature of 1200 oC.

We prepared 8 samples of non-silver and silver-added master alloys containing silicon to confirm the existence of nickel-silicides. We then prepared products made of 14K and 18K white gold by using the prepared master alloys containing 0.25, 0.35, and 0.50 wt% silicon to check for nickel release. We then employed the EN 1811 testing standard to investigate the nickel release of the white gold products, and we also confirmed the color of the white gold products with an UV-VISNIR- color meter. We observed NiSix residue in all master alloys containing more than 0.50 wt% Si with EDS-nitric acid etching. For the white gold products, we could not confirm the existence of NiSix through XRD after aqua regia etching. In the EN 1811 test, only the white gold products with 0.25 wt% silicon master alloys successfully passed the nickel release regulations. Moreover, we confirmed that our white gold products showed excellent Lab indices as compared to those of commercial white gold ones, and the silver-added master alloys offered a larger L index. Our results indicate that employing 0.25 wt% silicon master alloys might be suitable for white gold products without nickel-silicide defects and nickel release problems.