CuInGaSe(CIGS) mixed-source was prepared by hydride vapor phase epitaxy (HVPE). Each metal was mixed in regular ratio and soaked at 1090oC for 90 minutes in nitrogen atmosphere. After making the mixed-source to powder state,the pellet was made by the powder. The diameter of pellet is 10 mm. The CIGS thin film was deposited on soda lime glass evaporated Mo layer by e-beam evaporator. To confirm the crystallization, we measured X-ray diffraction (XRD).
High intensity X-ray peaks diffracted from (112), (204)/(220), (116)/(312) and (400) of CIGS thin film and from (110) of Mo were confirmed by XRD measurement.
The reduction of optical losses in mono-crystalline silicon solar cell by surface texturing is a critical step to improve the overall cell efficiency. In this study, we have changed the sub-micrometer structure on the micrometer pyramidal structure by 2-step texturing. The Ag particles were coated on the micrometer pyramid surface in AgNO3solution, and then the etching with hydrogen fluoride and hydrogen peroxide created even smaller nano-pyramids in these pyramids. As a result, we observed that the changes of size and thickness of nano structure on pyramidal surface were determined by AgNO3 concentration and etching time. Using 2-step texturing, the surface of wafers is etched to resemble the rough surface of a lotus leaf. Lotus surface can reduce average reflectance from 10 % to below 3 %. This reflectance is less than conventional textured wafer including anti-reflection coating.
Metamictization and color change in zircons from Cambodia and Tanzania were investigated. Elements analysis to detect radioactivity of elements such as U and Th, and spectroscopic analysis using UV-VIS and Fourier transform infrared spectroscopy were performed. According to the UV-VIS spectroscopic analysis, it was perceived that many and high intense absorption peaks appeared in blue and colorless zircons, while less and low intense absorption peaks appeared in uranium contained green and yellow zircons. It was found that those stones have made progress to the metamictization.
After heat treatment, we could detect opposite results. As the results of FTIR spectroscopy analysis, in the metamict green and yellow zircon, it is showed that 3-phonon combination mode bands of [SiO4]4− internal vibration in the region of 3100~3400 cm−1are broad and some of them disappear. However, the disappeared bands are observed again due to restored crystal lattice by the heat treatment. Also, U 4+peaks that can detect the uranium content in zircon appears at near 4800 cm−1in the green and yellow samples. From this investigation, we could observe the metamictization effect and color change in uranium-bearing zircon by heat treatment using spectroscopic analysis.
The effects of mole ratio(A/B) m and Ti-ion on the dielectric properties and microstructure of the microwave dielectric ceramics (Ca0.7Sr0.3)m(TiyZr1 − y)O3 were investigated. Ti ions substituted on Zr-sites in these modified CaZrO3composition strongly affect the sintering density and microstructure of the fired ceramic body. With increasing the amount of Ti substituted on Zr-sites, the sintered density rapidly increased and the dense microstructure was obtained for the compositions having mole ratio of 1.01, whereas the sintered density and microstructure are nearly constant with the content of Ti-ion for the compositions having mole ratio of 0.99. With increasing the content of Ti ion, the curve of TCC (Temperature Coefficient of Capacitance) as a function of temperature rotated clockwise and satisfied the COG characteristics for both of compositions with mole ratio of 0.99 and 1.01. The content of Ti ion seems to be more effective than mole with respect to the controlling of firing and TCC.
Thulium oxide-doped barium titanate ceramics for MLCCs with perovskite structure were prepared by a sintering process at 1320oC for 2 h in a reduced atmosphere. The effect of Tm2O3 addition on dielectric property of barium titanate ceramics has been studied in terms of their microstructures. Moreover, the phase identification of the dielectric specimens was conducted to define the secondary phase (pyrochlore). The specimen doped with 1 mol% Tm2O3 exhibited the highest dielectric constant. However, the dielectric constants of specimens with more than 2 mol% Tm2O3 to BaTiO3 were the lower values than that of 1 mol% doped one. The grain size and the formation of pyrochlore phase associated with the dielectric properties were examined through morphology development and the structural analysis. Furthermore, these data were compared with the property of the dielectric material doped with Er2O3. It could be concluded that the dielectric property of ceramic capacitors were attributed to the change of pyrochlore phase and the tetragonality of BaTiO3 with doping.
CoSb3-based skutterudite compounds are promising candidates as thermoelectric (TE) materials used in intermediate temperature region. In this study, sintering of CoSb3 powder and joining of CoSb3 to copper-molybdenum electrode have been simultaneously performed by spark plasma sintering technique. The Ti foil was used for preventing the diffusion of copper into CoSb3 and the Cu : Mo = 3 : 7 Vol. ratio composition was selected by the consideration of thermal expansion coefficients. The insertion of Ti interlayer between Cu-Mo and CoSb3 was effective to join CoSb3 to Cu-Mo by forming an intermediate layer of TiSb2 at the Ti-CoSb3 boundary. However, the formation of TiSb and TiCoSb intermediate layers deteriorated the joining properties by the generation of cracks in the interface of intermediate layer/CoSb3 and intermediate/intermediate layers.
In this paper, three types of CNT/TiO2 composite electrodes were prepared with different methods. The changes in XRD patterns showed that the Electrode A contained a mixed phase of anatase and rutile while the Electrode B and Electrode C contained a typical single and clear anatase crystal structure. From SEM micrographs, TiO2 particles were adhered on the surface of the CNT network in the forms of small clusters. The results of chemical elemental analysis indicated that the main elements such as C, O and Ti were existed. The results demonstrated that the efficiency of photoelectrocatalytic (PEC) oxidation for methylene blue (MB) was higher than that of photocatalytic (PC) oxidation. There was a clear enhancement trend of the MB degradation using the prepared CNT/TiO2 composite electrodes with an increase of applied potential. Finally, the prominent PEC activities of the CNT/TiO2 composites could be attributed to combination effects of photo-degradation of TiO2, electron assistant of CNT and function of applied potential.
Glass was fabricated by using refused coal ore obtained from Dogye coal mine in Samchuk. We additionally used soda ash and calcium carbonate as raw materials to make a glass with the chemical composition of soda-lime glass.
And the properties of glass were measured when limestone was used as natural raw materials instead of calcium carbonate as chemical raw materials. Transparent glass was fabricated by melting raw materials at 1550oC for 1 hr in an electrical furnace. The various kinds of glass samples were fabricated according to the kinds of refused coal ore and glass cullet.
The optical properties of transmittance and color chromaticity were measured by UV/VIS/NIR spectrometer and the thermal properties of thermal expansion coefficient and softening point were measured. Transparent glass with the transmittance of over 70% in visible range was fabricated by using normal refused coal ore and black colored glass with the transmittance of 0~35% was fabricated by using shell type refused coal ore. Therefore, it is concluded that refused coal ore can be used for raw materials to manufacture secondary glass products such as a glass tile and foamed glass panel for construction material.
The influence of CaO addition on the crystallization temperature, crystal types, and microstructure of L-A-S (Li2O-Al2O3-SiO2) glass-ceramics system fabricated from a coal bottom ash, produced at thermal power plant, was studied.
The glass transition and crystallization temperatures were shifted to the higher temperature position with increasing CaO content in a non-isothermal analysis using a DTA. The major crystalline phases of L-A-S glass-ceramics system produced were identified as β-spodumene (LiAlSi2O6) and eucryptite (LiAlSiO4). The glass-ceramics showed a bulk and surface crystallization behavior at a time. With increasing CaO content, the β-spodumene peak in XRD increased and some CaOrelated phases were formed. The surface crystal grown from the exterior to the center in glass-ceramics showed various shapes by amount of CaO added. Some cracks were generated at the glass-ceramics containing CaO above 9 wt% due to the mismatch of thermal expansion coefficients between a β-spodumene and CaO-related crystal phases.
The glass-ceramics made from the mixture of coal bottom ash, produced from a thermal power plant mixed with Na2O and Li2O was fabricated and their crystallization behavior was studied using a non-isothermal analyzing method.
The temperature for 50 % crystallization was higher than the exothermic peak temperature Tp at DTA curve and the quickest crystallization temperature was much the same as Tp as identified from the relationships of crystallized fraction and crystallization rate with temperature. By using Kissinger equation describing a crystallization behavior, the activation energy (262 kJ/mol), the Avrami constant (1.7) and the frequency (5.7 × 1016/s) for crystallization were calculated from which the nepheline crystal could be expected as showing an 1~2-dimensional surface crystallization behavior mainly with some bulk crystallization tendency at the same time. The actual observation of microstructure using SEM showed the considerable amount of surface crystals of dendrite and the bulk crystals with low fraction, so the prediction by the Kissinger equation was in accord with the crystallization behavior of glass-ceramics fabricated in this study.