Earticle

본 연구는 산화코발트와 산화망간의 특성을 고찰하고 산화망간의 비율 변화에 따른 발색실험을 진행하여 청화 데이터를 구축한 후 도예작업에 적용해봄으로써, 다채로운 청화 색상 표현의 가능성을 모색하는 데 목적이 있다. 산화코발트는 페르시아가 원산지로 고온번조 과정에서 발색이 고르고 깊은 푸른색을 나타내는 특징이 있는데 이를 채화(彩畵)안료로 만든 것이 청화이다. 청화의 회화적 특성을 최초로 도예에 적용한 건 중국 송·원대(宋·元代)의 경덕진요(景德鎭窯) 도공들이었다. 송대(宋代)에 사용된 중국산 청화안료의 경우 산화망간의 함유량이 많고 매우 푸른색으로 발색 되는 페르시아산과 다르게 암갈색 및 흑색을 띠고 있다. 이를 통해 산화망간이 청화의 발색에 영향을 미치고 있음을 유추할 수 있었으며, 그 특성을 활용한다면 도예작업에 다채로운 청화 표현이 가능하리라 판단되었다. 따라서 도예작업에서 널리 사용되고 있는 산화망간의 특성을 이해하고 첨가제로 사용하여 비율 변화에 따라 나타나는 청화의 발색에 중점을 두어 연구를 진행하였다. 연구과정은 첫째, 연구의 중심이 되는 청화의 기원과 특성, 그리고 첨가제로 활용되는 산화망간의 특성을 고찰하였다. 둘째, 실험에 사용할 시편을 동일한 두께와 크기로 제작하고 810℃로 1차 소성하였다. 셋째, 산화망간의 발색실험에 앞서 산화코발트의 비율 변화에 따른 청화 발색실험을 진행하여 이상적 청화 데이터를 도출하였다. 청화 발색실험은 산화코발트에 일정 비율로 변화를 주어 10개의 청화를 만든 후 준비된 시편에 붓을 이용해 횟수와 농도 변화로 구분하여 두 가지 방법으로 진행하였으며, 1250℃로 2차 소성하였다. 소성 결과, 채도와 명도가 다양한 한색(寒色) 계열의 청색이 나타났으며, 산화코발트 비율이 높아짐에 따라 청화안료가 뭉쳐 고르게 퍼지지 않아 뚜렷한 농담(濃淡)변화를 관찰할 수 없었다. 청화 발색실험에서 가장 이상적 발색을 보인 시편의 조성비는 백색자기토 100 : 산화철 7 : 산화코발트 5였으며, 이를 기본 청화 데이터로 구축하였다. 넷째, 도출한 기본 청화 데이터에 산화망간의 비율변화에 따른 발색실험을 진행하여 청화 데이터를 도출하였다. 실험 결과, 산화망간의 비율이 높아질수록 채도와 명도가 낮아졌고 산화망간이 융제 및 착색제 역할을 하여 전체적으로 뭉침 없이 부드럽고 차분하게 발색됨을 알 수 있었다. 또한 물에 잘 녹지 않는 산화망간의 특성으로 인하여 그 비율이 높아질수록 반점의 수가 증가하는 특징이 나타났다. 채도와 명도가 낮아지면서 한국화에서 사용하는 먹(墨)과 흡사한 색을 띠었고, 실험을 통해 도출한 다양한 시료를 사용하여 채화(彩畵)한다면 보다 다양한 청화의 색상 표현이 가능하지 않을까 하는 생각이 들었다. 전체 실험과정의 시편분석을 통해 가장 이상적인 발색을 보인 시편을 청화시료로 도출하여 데이터를 구축하였다. 가장 이상적인 발색을 보인 시편은 6번 시편(백색자기토 100 : 산화철 7 : 산화코발트 5 : 산화망간 25)이었으나 도예작업으로 적용하는 데 있어 다양한 색상 유도를 위하여 한 가지 표준데이터가 아닌 두 가지 데이터를 함께 도출하였다. 이는 단색의 청화표현이 아닌, 다양한 색상변화 적용을 통해 도예작업에서 회화표현의 가능성을 모색하기 위함이다. 마지막으로 산화망간의 비율 변화에 따른 청화 발색실험으로 도출한 청화시료 세 가지를 채화(彩畵)작업과정을 거쳐 실질적 도예작업에 적용해봄으로써, 청화작업에서 다양한 색상표현의 가능성을 모색하여 제시하였다.

The purpose of this study is to investigate the unique characteristics of cobalt oxide and manganese oxide as well as color formation by varying the ratio of manganese oxide in order to develop coloring data and apply them onto ceramics and to address the possibilities of expressing a wide range of white and blue. Cobalt oxide, originated from Persia, has a feature of even and deep blue color due to the high-temp firing process, and it is used for a coloring pigment for the white and blue drawing. The Chinese potters of the Song Dynasty and the Yuan Dynasty were the first one applying the painting characteristics of the white and blue drawing onto ceramics. In the case of the pigment used for the white and blue drawing during the Song Dynasty, its content of manganese oxide was high and had hues of dark brown and black, unlike of the Persian pigment which was bright blue. Therefore, it could conclude that the content of manganese oxide has an influence on the color formation of the white and blue drawing and if it is used properly, it would be able to express various blue colors on ceramics Thus, this study was designed to understand the properties of manganese oxide, widely used in pottery works, and focus on color formation of the white and blue drawing by varying the ratio of manganese oxide. For the first part of this study, the origin and characteristics of the white and blue drawing, a subject of this study, were investigated along with of manganese oxide, used as an additive. Second, specimens, having the same thickness and size, were sintered at 810℃ primarily. Third, prior to the coloration test of manganese oxide, the cobalt oxide coloration test was executed by changing the ratio of cobalt oxide to have the ideal blue color data. For the cobalt oxide coloration test, 10 specimens were prepared first. Then, varying the ratio of cobalt oxide by changing the no. of brush application or varying the concentration and the specimens were sintered at 1250℃ secondarily. After the sintering, blue in the system of cold color was appeared and its brightness and chroma were highly varied. However, with an increase in the ratio of cobalt oxide, there were more lumps so it was not possible to observe a distinctive change in shade. The composition ratio of the specimen with the most ideal color formation was white porcelain 100: iron oxide 7: and cobalt oxide 5, and it was used as the basic blue coloring data. Fourth, the coloration test was executed by varying the ratio of manganese oxide to have the data on the blue and white drawing. From the test, it was shown that with the increased ratio of manganese oxide, the chroma and brightness decreased and the no. of spots also increased. In addition, since manganese oxide acted as a flux and a coloring agent, the entire hue was somewhat soft and calm without lumps. Also, due to the insolubility of manganese oxide, the no. of spots increased with the increased ratio of manganese oxide. As the chroma and brightness became lower, it became similar with the ink stick, generally used for Korean paintings. So, it would be possible to express more various colors of blue by using various pigments. Through the analysis of entire specimens, the specimen with the most ideal color was chosen as the sample. The specimen with the most ideal color was the no. 6 (white porcelain 100: iron oxide 7: cobalt oxide 5: manganese oxide 25), but to have a wide range of color on ceramics, two data were created, instead of one. It was to investigate the possibility of painting expressions through application of various colors rather than solely for the white and blue drawing in which a single color is used. For the last, by applying three pigments, created from the color formation test in which the ratio of manganese oxide was varied, on actual ceramics, it evaluated and suggested the possibility of expression of a wide range of colors in the white and blue drawing.

The present study is concerned with the removal of Manganese from aqueous solution by adsorption onto low cost adsorbent. Manganese oxide coated zeolite (MOCZ) and iron oxide coated zeolite (FOCZ) were investigated as an adsorbent for the removal of Mn2+. Batch adsorption experiments were performed as a function of pH, contact time and Mn concentration. The optimum conditions for maximum adsorption by MOCZ were attained at pH=7, Mn concentration of 5 mg/L and for FOCZ at pH=8, concentration of 4mg/L. Manganese detection was carried out by Inductive Coupled Plasma - Atomic Emission Spectroscopy (ICP-AES). Furthermore, Results showed that MOCZ had a good adsorption performance for the adsorption of Mn rather than FOCZ, the adsorption capacity of MOCZ was 0.21 mg/g at 15 min. Langmuir, Freundlich, isotherm models were selected to evaluate the adsorption of Mn. It was found that the Langmuir isotherm model with coefficients of determinations (R2) of 0.97 and 0.94, respectively, best fits the Mn adsorption onto absorbents. Finally, Obtained results from experiments prove that MOCZ is suitable for removal of manganese from water and it is comparable with FOCZ.

The influence of MnO2 on the sintering property and PTCR behavior of(Ba0.8Sr0.2)TiO2 has been investigated. And the densities, grain sizes and electrical resitivities of specimens were measured as a function of doping with Mn ion of varying concentration. The density and grain size of the sintered specimens were almost the same regardless of MnO2 addition up to 0.2mol% MnO2. But in the case of 0.25mol% MnO2 addition, abnormal grain growth was appeared. So the grain size distribution was wide and density decreased greatly. The room-temperature resistivity increased as Mn content increased and the temperature coefficient of resistivity was highest in the case of 0.15mol% MnO2 addition.

The effects of MnO2 doping on the crystal structure, ferroelectric, and piezoelectric properties of (K,Na)NbO3 (KNN) ceramics have been investigated. MnO2 was found to be effective in enhancing the densification and grain growth during sintering. X-ray diffraction analysis indicated that Mn ions substituted B-site Nb ions up to 2mol%, however, further doping induced unwanted secondary phases. In comparison with undoped KNN ceramics,the well developed microstructure and the substitution to B-sites in 2 mol% Mn-doped KNN ceramics resulted in significant improvements in both piezoelectric coupling coefficient and electromechanical quality factor.

Plastic pollution is threatening human health and ecosystems, resulting in one of the biggest challenges that humanity has ever faced. Therefore, this study focuses on the preparation of macroporous carbon from biowaste (MC)- supported manganese oxide (MnO2) as an efficient, reusable, and robust catalyst for the recycling of poly(ethylene terephthalate) (PET) waste. As-prepared MnO2/MC composites have a hierarchical pore network and a large surface area (376.16 m2/g) with a narrow size distribution. MnO2/MC shows a maximum yield (98%) of bis(2-hydroxyethyl)terephthalate (BHET) after glycolysis reaction for 120 min. Furthermore, MnO2/MC can be reused at least nine times with a negligible decrease in BHET yield. Based on this remarkable catalytic performance, we expect that MnO2-based heterogeneous catalysts have the potential to be introduced into the PET recycling industry.

Fiber supercapacitors have attracted significant interest as potential textile energy storage devices due to their remarkable flexibility and rapid charge/discharge capabilities. This study describes the fabrication of a composite fiber supercapacitor (FSC) electrode through a multi-shell architecture, featuring layers of carbon nanotube (CNT) conductive shells and MnO₂ nanoparticle active shells. The number of layers was adjusted to assess their impact on FSC energy storage performance. Increasing the number of shells reduced electrode resistance and enhanced pseudocapacitive characteristics. Compared to the MnS@1 electrode, the MnS@5 electrode exhibited a high areal capacitance of 301.2 mF/cm², a 411% increase, but showed a higher charge transfer resistance (RCT) of 701.6 Ω. This is attributed to reduced ion diffusion and charge transfer ability resulting from the thicker multi-shell configuration. These results indicate that fine-tuning the quantity of shells is crucial for achieving an optimal balance between energy storage efficiency and stability.

Titanium dioxide shows polymorphism on heating to a higher temperature. This transformation is strongly dependent on temperature and time of heating. Pure Titania pulp containing amorphous titania was heated at different temperatures and for different times. Above 650oC the anatase phase evolved and between 900-1000 oC, an anatase-rutile transformation occurred. The anatase-rutile transformation in TiO2 in the presence of CuO and MnO2 was investigated. The different phases of TiO2 were determined using powder XRD. Other methods such as chemical analysis, scanning electron microscopy, surface area measurements and crystallite size calculations were used for the characterization of the samples. The transformation temperature was found to be much lowered in the presence of the above metal oxides. Also the method of preparation of metal oxide doped TiO2 affects the polymorphism.

The microstructure and electrical properties of Pb[(Sb1/2 Nb1/2)0.08 Zr0.49 Ti0.48]O3 with MnO2 addition have been investigated in this work. The amount of MnO2 addition was 0, 0.4, 0.8, 1.2, 2.0 wt%, respectively. The soild solution range of MnO2 that assumed in this composition according to thevariations of micro-structure and electrical properties was 0.4-0.8 wt%.

The microstructure and electrical properties of 0.02Pb[Cd1/2W1/2)O3-0.505PbZrO3-0.475PbTiO3 with MnO2 addition have been investigated. The amount of MnO2 addition was 0, 0.2, 0.4, 0.6, 0.8, 1wt%, respectively. When MnO2 is added up to 0.2wt%, Mn3+ which is substituted for Ti4+ site make hole and act as a acceptor. When MnO2 is added over 0.2wt% Mn3+ which is substituted for Cd2+ site create electron and act as a donor. The variation of grain size show that it was rapidly increased by 0.4wt% addition of MnO2, and while that in the range of over 0.6wt% addition of MnO2 it was decreased. The solid solution range of MnO2 that assumed in this composition according to the variations of microstructure and electrical properties was 0.4-0.6wt%.

To improve the electrical conductivity of MnO2, the composite material of mesoporous carbon and MnO2 was synthesized. The mesoporous carbon was prepared by a polymerization-induced colloid aggregation method (PICA) using melamine formaldehyde resin as the carbon precursor and fumed silica (14 nm) as a hard template. The composite of mesoporous carbon and MnO2 was prepared by a redox reaction between KMnO4 and oxygen on the surface of carbon. The synthesized mesoporous carbon has a high specific surface area (~ 1500 m2 g-1) and an average pore size as large as 7 nm. Electrochemical properties of the mesoporous carbon-MnO2 composite were elucidated by cyclic voltammograms and galvanostatic chargedischarge in 1.0 M Na2SO4 electrolyte. A specific capacitance of 128 Fg-1 was obtained at a current density of 0.1 Ag-1.

Effects of MnO2 addition on themicrostructure, dielectric and piezoelectric properties of Rhombohedral, Tetragonal and Morphotropic phase boundary(MPB) in Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3 system were investigated and respectively the amount of MnO2 addition was 0, 0.2, 0.5, 1.0, 3.0wt%. In the tetragonal region, compared with the Rhombohedral and Morpotropic phase boundary, Mechanical quality factor(Qm), Curie temperature(Tc) and Dissipation factor were promoted by addition of MnO2. According to the results of the microstructure, dielectric and piezoelectric properties, the solid solution range of MnO2 addition in this system was 0.2-0.5wt%.

In the ceramics of PFN-PFW system modified with MnO2 dielectric properties and the relation of its microstructure have been investigated. The amount of MnO2 variations was 0, 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3 mol%, respectively. In the result of the microstructure and electrical properties, the solid solution range of MnO2 was 0.15 mol%.

이산화망간은 전지의 활성물질로서 우수한 특성을 가지고 있고 가격도 저렴한 재료로서 각종 1차전지에 사용되어왔다. 그러나 이산화망간을 이용한 2차 전지에 대한 연구는 그렇게 많지 않다. 최근 이산화망간의 충전가역성에 관하여 황산아연을 전해질로 하는 이산화망간 아연전지가 재충전이 가능하다는 보고가 있다. 여기서는 이산화망간이 황산아연수용액 중에서 가역적으로 충전방전이 가능한 것을 토대로 2차전지로서의 가능성에 대해 서술한다.

Manganese dioxide is the material which has a good characteristic property for a secondary cell. We have surveyed on rechargeable battery of zink-manganese dioxide using aqueous solution and we also surveyed on redox reversibility of zink-manganese dioxide for checking up possibility for a secondary cell. We have found out to be active for charging and discharging of those.

$MnO_2$ is used for the oxide electrode of electrochemical equipments because of its good electric conductivity and low oxygen overpotential. The effect of additives on the properties of $MnO_2$ has been investigated to enhance the electric conductivity and the stability in an acid solution. In this research, the effect of Ni addition on ${\beta}-MnO_2$ was studied by the theoretical quantum chemical method. The calculation was carried out by the discrete variation $X{\alpha}$ method, which is a sort of the first principle method and use Hatre-Fock-Slater approximation. The electron energy level, the density of state, the bond overlap population, the charge density distribution and the net ionic transfer between cations and anions were calculated and discussed. The used cluster model was $(Mn_{10}NiO_{44})^{-44}$.