Local structures and electronic band states of α−Fe2O3 polycrystalline particles in the glazes of the HIZEN celadons produced in the Edo period of Japan, by means of X-ray absorption spectra (II)

Hidaka, M.,Ohashi, K.,Wijesundera, R. P.,Kumara, L. S. R.,Sugihara, S.,Momoshima, N.,Kubuki, S.,Sung, N. E. SciELO 2011 Cerâmica Vol.57 No.342

<▼1><P>HIZEN celadon glazes produced in 1630's to 1790's (Edo period, Japan) have been investigated by means of X-ray absorption spectra (XAS) near a Fe-K edge by using synchrotron radiation and a Mössbauer spectrum. The XAS suggest that the local structure around Fe2O3 fine powders is slightly different between the Izumiyama ceramics of mainly the Quartz-SiO2 and Ohkawachi ceramics of mainly the feldspar of (K,Na)Si3O8 (Sanidine), and that the glazes of the HIZEN celadons include the Fe2O3 fine powders in the glassy state, though the X-ray diffraction patterns of the glassy celadon glazes do not show any peaks of the Fe2O3 structure. The Mössbauer spectrum suggests that the celadon glaze of Seiji (m) includes only Fe3+ ions, but not Fe2+ ions. This indicates the existence of Fe2O3 in the celadon glaze. It is interpreted that the colored brightness of the HIZEN celadons is induced by the structural properties of the used raw celadon ceramics and the other transition-metal ions of Cr, Cu, Zn in the celadon glazes, but not by the chemical reaction from Fe2O3 to FeO under the deoxidizing thermal treatment at higher temperature in a kiln.</P></▼1><▼2><P>Esmaltes de celadon Hizen produzidos dos anos 1630 a 1790 (período Edo, Japão) foram investigados por meio de espectros de absorção de raios X (XAS) próximos da linha Fe-K usando radiação síncrotron e espectro Mossbaues. Os resultados de XAS sugerem que a estrutura local em pós finos de Fe2O3 é levemente diferente entre as cerâmicas Izumiyama principalmente o quartzo e cerâmicas Ohkawachi principalmente do feldspato (K,Na)Si3O8 (Sanidine), e que os esmaltes dos celadons Hizen incluem finos pós de Fe2O3 no estado vítreo, embora os difratogramas de raios X dos esmaltes celadon não mostrem picos da estrutura do Fe2O3. O espectro Mossbauer sugere que os esmaltes celadon de Seiji (m) incluem somente íons Fe3+, mas não Fe2+. Isto indica a existência de Fe2O3 no esmalte celadon. É feita a interpretação que o brilho nas cores dos celadons Hizen é induzido pelas propriedades estruturais das cerâmicas básicas de celadon e os outros metais de transição Cr, Cu, Zn nos esmaltes celadon, mas não pela reação química entre Fe2O3 para FeO sob tratamento térmico desoxidante em forno a altas temperaturas.</P></▼2>

Electronic states and local structures of Cu ions in electrodeposited thin films of Cu and Cu₂O from X-ray absorption spectra

Wijesundera, R. P.,Hidaka, M.,Siripala, W.,Choi, Sun-Hee,Sung, Nark Eon,Kim, Min Gyu,Lee, Jay Min WILEY-VCH Verlag 2006 Physica status solidi. PSS. B, Basic solid state p Vol.243 No.8

<P>X-ray absorption spectra near Cu K edges have been obtained for Cu and Cu<SUB>2</SUB>O thin films potentiostatically electrodeposited in an acetate bath. The electronic states of Cu ions and the local structures around these ions are studied using X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy, respectively. The inner strains in micro-size crystals of the electrodeposited Cu thin film are less than those of a commercial Cu foil. The partial electronic states of Cu ions near the Fermi level (E <SUB>F</SUB>) and the local structure around these ions show a systematic transformation from a Cu<SUB>2</SUB>O single phase (Phase I), to a Cu<SUB>2</SUB>O–Cu intermediate phase (Phase II) and a Cu single phase (Phase III) in thin films electrodeposited on titanium substrates for the deposition potential range of –100 to –900 mV. Phase II consists of independent Cu<SUB>2</SUB>O-like and Cu-like local structures, but not a Cu<SUB>2</SUB>O–Cu complex. Phase II is also characterized by a transition region from the semiconductor Cu<SUB>2</SUB>O to the metal Cu for the Cu electronic state having a p-like character near the Fermi level in the oxygen O-2p conduction band. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>

Structural properties of the red-color overglazes on the Kakiemon-style porcelains produced in the later 17th century by means of X-ray diffraction (I)

Hidaka, M.,Horiuchi, H.,Ohashi, K.,Wijesundera, R. P.,Kumara, L. S. R.,Choi, Jae-Young,Park, Yong Jun SciELO 2009 Cerâmica Vol.55 No.334

<▼1><P>Kakiemon-style porcelains produced at Arita areas (SAGA) in Kyushu Island are famous Japanese porcelains. The porcelain-techniques creating its elegant and bright red-color underglaze and overglaze were found and developed in 1650's (early Edo period) first by Kakiemon kiln. Red-color overglaze and transparent glaze of the Kakiemon-style porcelains have been investigated by means of X-ray diffraction using synchrotron radiation. The results suggest that the red-color brightness is mainly induced by micro-structural correlation between α-Fe2O3 fine particles, as red-color emission elements, and other oxides of SiO2, Al2O3, CaO, KNaO, PbO. The stability of the red-overglaze on the porcelain surface is related to interfacial fusion of the glasses existing in the fritted red-overglaze and the transparent glaze on the porcelain body. The ancient porcelain-techniques of the Kakiemon-style porcelains are clearly based on the micro-structural and material properties of the overglazes, the underglazes, and the transparent glazes, though the techniques were experimentally and accidentally found and developed in the Edo period.</P></▼1><▼2><P>As porcelanas do estilo Kakiemon produzidas nas áreas de Arita (SAGA) na ilha Kyushu são porcelanas japonesas famosas. As técnicas de produzir porcelanas com os elegantes e brilhantes vidrados de cores vermelho brilhante foram encontradas e desenvolvidas nos anos 1650 (início do período Edo) primeiramente em fornos Kakiemon. Vidrados vermelhos e vidrados transparentes de porcelanas do estilo Kakiemon foram investigadas por meio de difração de raios X com radiação sincrotron. Os resultados sugerem que o brilho de cor vermelha é principalmente induzido pela correlação microestrutural entre finas partículas de α-Fe2O3, como elementos emissores de cor vermelha, além de outros óxidos como SiO2, Al2O3, CaO, KNaO, e PbO. A estabilidade dos vidrados na superfície da porcelana com vidrado vermelho está relacionada com a fusão interfacial dos vidros existentes no vidrado vermelho calcinado e o vidrado transparente do corpo da porcelana. As antigas téncias de porcelana do estilo Kakiemon são claramente baseadas nas propriedades microestruturais do material dos vidrados sobrepostos, os sub-postos e os transparentes, embora as técnicas tenham sido encontradas e desenvolvidas experimental e acidentalmente no período Edo.</P></▼2>

Thermally evaporated CdS/CdTe thin film solar cells: Optimization of CdCl2 evaporation treatment on absorber layer

Kumarasinghe R.K.K.G.R.G.,Kumarasinghe P.K.K.,Wijesundera R.P.,Dassanayake B.S. 한국물리학회 2022 Current Applied Physics Vol.33 No.-

CdCl2 treatment is crucial in the fabrication of highly efficient CdS/CdTe thin-film solar cells. This study reports a comprehensive analysis of thermal evaporated CdS/CdTe thin-film solar cells when the CdTe absorber layer is CdCl2 annealed at temperatures from 340 to 440 ◦C. Samples were characterized for structural, optical, morphological and electrical properties. The films annealed at 400 ◦C showed better crystallinity with a cubic zinc blende structure having large grains. Higher refractive index, optical conductivity, and absorption coefficient were recorded for the CdTe films annealed at 400 ◦C with CdCl2. Optimum photoactive properties for CdS/ CdTe thin-film solar cells were also obtained when samples were annealed at 400 ◦C for 20 min with CdCl2, and the best device exhibited VOC of 668.4 mV, JSC of 13.6 mA cm 2, FF of 53.9% and an efficiency of 4.9%.

Correlation between local structures and partial electronic band states in ferroelectric Bi_4-XLa_XTi₃O₁₂; 0.0 <or=x <or='1.46</main'></or=x>

Hidaka, M.,Wijesundera, R.P.,Kumara, R.,Noguchi, Y.,Miyayama, M.,Choi, S.-H.,Sung, N.E.,Kim, M.G. INSTITUTE OF CHEMICAL TECHNOLOGY/INSTITUTE OF INOR 2009 Ceramics Vol.53 No.2