Papers by Keyword: Delafossite

Abstract: The development of the supercapbattery has become the focus of energy storage research due to their potential to increase energy and power density. This research is focused on developing a modification of silicon (Si) porous as an anode with Al₂O₃/CuCrO₂/AC composite as a cathode of supercapacitor. These electrodes were synthesized using LA133 binder with deionized water as solvent. The supercapacitor electrode uses an aluminum foil substrate, while the Si electrode uses a cupper foil substrate. The structural and morphological characterization of the electrodes were identified through XRD, FTIR, and SEM tests, while the electrochemical performance characterization using Galvanostatic Charge-Discharge (GCD) instruments. The results of XRD data analysis of thin film electrodes of supercapacitor showed diffraction peaks which indicated the phases Al₂O₃/CuCrO₂/AC and Si porous. The absorption functional groups of Al₂O₃/CuCrO₂/AC and Si porous were identified through FTIR characterization. The results of SEM showed the addition of CuCrO₂ and structure modification of silicon into porous caused increasing value of porosity. The electrochemical performance of the optimum point at Al₂O₃/CuCrO₂/AC condition, showing a specific capacitance of 50.3 F/g, an energy density of 36.499 Wh/kg, and a power density of 433.6 W/kg. The combination of Al₂O₃/CuCrO₂/AC//Si Porous 16 for supercapbattery devices shows performance with a specific capacitance of 14.4 F/g, an energy density of 6.1 Wh/kg, and a power density of 33.6 W/kg. These results indicate an increase in electrochemical performance compared with Si anodes without modification.

Abstract: In this study, we investigated a CuAl_0.9Fe_0.1O₂ compound prepared at two different sintering temperatures in order to find out the effect of sintering temperature on the compound's figure of merit of thermoelectric properties. The thermoelectric CuAl_0.9Fe_0.1O₂ compound was prepared from high purity grade Cu₂O, Al₂O₃ and Fe₂O₃ powders. The mixture of these powders were ground and then pressed with uniaxial pressure into pellets. The pellets obtained were sintered in the air at 1423 K and 1473 K. X-ray diffraction (XRD) patterns showed a single phase of CuAl_0.9Fe_0.1O₂ with rhombohedral structure, , along with a trace of CuO second phase. Moreover, the XRD peaks of the sample sintered at 1423 K indicated that more Fe³⁺ atoms replaced Al³⁺ atoms in this sample than they did in the sample sintered at 1473 K. The average grain size of the CuAl_0.9Fe_0.1O₂ compound prepared increased with increasing sintering temperature, whereas its mean pore size and porosity decreased with increasing sintering temperature. The dispersed small pores markedly decreased the thermal conductivity of the compound, while the Fe³⁺ substitution of Al³⁺ increased its electrical conductivity. The highest figure of merit (ZT) found was 0.021 at 973 K in the CuAl_0.9Fe_0.1O₂ sample sintered at 1423 K. Our findings show that this low-cost material with a reasonable figure of merit is a good candidate for thermoelectric applications at high-temperature.

Abstract: The P-type transparent conductive oxide CuAlO₂ was prepared by solid state reaction in this paper. The chemical state, phase structure, microstructure and optical properties were characterized by Differential Thermal Analysis ( DTA),X-ray diffraction ( XRD),Scanning Electron Microscope ( SEM) and Infrared Spectroscopy ( IR) respectively. Testing results show that the product is really p-type transparent conductive oxide CuAlO₂. CuAlO₂ phase began to form at about 1047.7 °C.It can be formed with high density and a high infrared light transmittance of the conductive oxide at 1150 °C.

Abstract: In this paper, the CuFeO₂ compound were prepared by classical solid state reaction (CSSR) and direct powder dissolved solution (DPDS) method from starting material metal oxides and metal powders. Preparation of two methods shows that, direct powder dissolved solution faster recover phases than classical solid state reaction method. The fastest method gets from starting materials Cu and Fe metal powders, the electrical conductivity, Seebeck coefficient, carrier concentration and mobility are 10.68 S/cm, 244.59 μV/K, 12.86×10¹⁶ cm^-3 and 494.96 cm²/V.s, respectively. In addition, each CuFeO₂ compounds were investigated on crystal structure and electrical properties. From XRD and SEM results, all samples have a crystal structure delafossite-typeand a large grain boundary more than 15 μm by electrical conductivity corresponds to grain boundary and lattice parameter: a increases. Within this paper, from above results exhibit that preparation CuFeO₂ from Cu and Fe by direct powder dissolved solution method most appropriate for thermoelectric oxide materials due to high active for preparation else high lattice strain and high power factor are 0.00052 and 0.64×10^-4 W/mK², respectively.

Abstract: Single-phase delafossite type Mg-doped copper-chromium oxide thin films were prepared on c-sapphire, quartz glass and n-Si substrates by direct current (DC) magnetron sputtering using a CuCr_0.97Mg_0.03O₂ (CCMO) ceramic target, followed by post annealing at 800 °C in a nitrogen atmosphere. X-ray diffraction (XRD) revealed that the film deposited on c-plane sapphire was highly c-axis oriented, while the films on quartz glass and Si only showed weak (0 1 2) peak. The transparencies of the films on c-sapphire and quartz glass were over 60 % in the visible light region and the direct bandgap of both films were estimated to be 3.16 eV. The in-plane resistivities were 0.24 Ωcm and 7.68 Ωcm for the crystallized films on c-sapphire and quartz glass, respectively. The electrical property of the formed CCMO/n-Si junction was found to be rectifying with a ratio of ~15 at ±2 V.

Abstract: Transparent conducting oxides (TCOs) are well known and have been widely used for a long time in optoelectronics industries. The most popular TCOs have n-type characteristics. However p-type material is not well established and examined. The delafossite-CuAlO₂ is one of the p-type TCOs. In this paper, amorphous Cu-Al-O films were deposited onto (100) p-type silicon substrate by magnetron sputtering. After that, the films were annealed at 800°C for 2 h in different partial oxygen levels ranging from 5*10^-5 to 1 atm with N₂, air, and O₂. X-ray diffraction patterns showed that as-deposited films were amorphous. In addition, delafossite-CuAlO₂ (R m and P6₃/mmc phase) appeared at 800°C in N₂, but monoclinic-CuO and spinel-CuAl₂O₄ phases existed in air and O2. The formation of delafossite-CuAlO₂ phase can be explained with thermodynamics. The optoelectronic properties of delafossite-CuAlO₂ films were also measured. The direct optical bandgap was around at 3.3 eV, which is comparable with literature data. The electrical conductivity was obtained to be 6.8*10^-3 S/cm. The hot-probe method employed to measure the electrical property of the films, which indicates that delafossite-CuAlO₂ films have p-type characteristics.

Abstract: The preparation of single-phase CuLaO2 with delafossite-type structure by means of the solid-state reaction method was investigated using X-ray diffraction. The results showed that notwhistanding the fact that there was a trace of metallic copper, nearly single-phase CuLaO2 was obtained by using La(OH)3 as a lanthanum source and by firing the mixed powder with nonstoichiometric composition ratio of La(OH)3:Cu2O =1:1.425 in a vacuum at 1273 K for 10 h. The measurement of electrical conductivity and Seebeck coefficient showed that CuLaO2 thus obtained was a p-type semiconductor and had a Seebeck coefficient of approximately 70 /V/K.