Cell performance was measured at 773-1073 K for Ni-GDC(Gd-doped ceria) anode-supported GDC film (60 μm thickness) with SrRuO₃ cathode using a 3 vol% H₂O-containing H₂ fuel. Reduction of particle size (< 1 μm) of SrRuO₃ cathode was effective to decrease the voltage drop at the cathode because of the increased length of triple phase boundary (GDC electrolyte-SrRuO₃ cathode-O₂ gas). Open circuit voltage (OCV) of GDC electrolyte in an anode atmosphere without H₂ fuel was close to the value calculated by Nernst equation for no electronic conduction. However, the OCV in a H₂-containing atmosphere decreased from the values by Nernst equation owing to the increased electronic conduction in a GDC film. This tendency of decrease in OCV became significant for thinner GDC film. This result was interpreted by the dissolution and dissociation of H₂ fuel in a GDC film to form protons and electrons (H₂ → 2H⁺ + 2e^-).

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Electrochemical reforming of 50% CH₄-50% CO₂ mixed gas was investigated using the cell of Ni or Ru-GDC (Gd-doped ceria) cathode/porous GDC electrolyte/Ni, Ru or SrRuO₃-GDC anode system at 400°-800°C under 1.25 V/cm of electric field strength. Use of Ni as anode accelerated the decomposition of CH₄ (CH₄ → C + 2H₂) and caused the blockage of supplied gas because of the deposition of carbon in the open spaces of anode. On the other hand, Ni in cathode worked well to reduce CO₂ to CO and O^2- ions (CO₂ + 2e^- → CO + O^2-). Use of Ru in both electrodes gave little problems to oxidize CH₄ in anode (CH₄ + O^2- → CO + 2H₂ + 2e^-) and to reduce CO₂ in cathode. SrRuO₃ in anode worked also to oxidize CH₄. This oxide reacted with H₂ produced in the reforming of CH₄ to form Ru and Sr. Sr evaporated at 800°C during the reforming. Stable formation of a H₂-CO fuel was measured for 11-13 h at 800°C using the cells with Ni or Ru cathode and Ru anode.

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The effect of SO₂ and NO on the catalytic oxidation of diesel particulate (soot) was studied over two Ce oxides, CeO₂ and BaCeO₃. Silver catalysts loaded on both Ce oxides exhibited the high activity, which was accelerated by the pretreatment in a flow of NO/O₂ mixtures. The adsorption species in the form of NO₂/NO₃ should play a role of oxidizing agents for soot. However, the pretreatment of Ag/CeO₂ in a flow of SO₂/O₂ mixtures caused significant deactivation. Strong adsorption of SO₂ onto active site at the three-phase boundary between soot, Ag/CeO₂ and the gas phase would be a reason for the deactivation. Ag/BaCeO₃ was found to be a catalyst having much improved tolerance to SO₂. The tolerance may be explained by the SO₂ adsorption site residing apart from the catalytically active oxygen site.

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Hollow particles of nitrogen doped TiO₂ were fabricated by a newly developed method based on the spray-induced hydrolysis. An aqueous solution of urea was sprayed into a titanium tetraisopropoxide (TTIP) / hexane solution, inducing the rapid hydrolysis of TTIP at the interface between the droplets of urea solution and TTIP solution. The resultant hollow particles were converted to N-doped TiO₂ with anatase crystal structure by heat treatment. The absorption ability of visible light was remarkably improved by nitrogen doping. The hollow N-doped TiO₂ particles showed higher photocatalytic activity estimated by the decomposition of methylene blue (MB) compared to undoped TiO₂ particles.

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The photocatalytic activity of 0.5 wt% Ni-loaded LiCa₂Ta₃O₁₀ for water splitting into a stoichiometric H₂/O₂ mixture increased about 4-fold after heat treatment at ≥ 500°C in a flow of N₂. Local structures of the photocatalysts before and after heat treatment have been studied using XRD and XAFS. Rietveld refinement of XRD patterns revealed that the heat treatment decreased the thickness of a triple-layered perovskite slab and thus increased the distortion of octahedral TaO₆ units in the both side of triple-layers. The resulting increase of dipole moment is considered to be efficient for promoting a charge separation step in the photocatalytic process. The heat treatment also converted the Ni cocatalysts from NiO/Ni core-shell to fully oxidized structure, but its effect on the photocatalytic activity was negligible.

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Magnesium hydroxide powder is used as a flame retardant in resin cable and wire sheathing. To be considered effective as a flame retardant, magnesium hydroxide needs to consist of primary particles having a diameter of 0.5-1.5 μm and has to be less cohesive with a small specific surface area of 5 m²·g^-1. However, magnesium hydroxide obtained from seawater and slaked lime slurry consists of polycrystalline secondary particles with an average diameter of about 3 μm that result form scale-shaped primary particles and have a high specific surface area of over 10 m²·g^-1, making magnesium hydroxide highly hygroscopic and thus unsuitable for application as a flame-retardant. In this study, a mechanism for reducing the specific surface area of polycrystalline magnesium hydroxide powder was investigated to reduce its hygroscopicity. The Brunauer-Emmett-Teller (BET) specific surface area was found to change depending on the drying rate and could be reduced upon dehydration at a low drying rate. A mechanism for reducing the BET specific surface area of magnesium hydroxide was identified: when magnesium hydroxide was dehydrated at a low drying rate, the decreasing drying period increased and the supersaturation of magnesium hydroxide by the moisture remaining in the pores was prolonged. Consequently, the primary particles of magnesium hydroxide grew larger, and the number of 3-10 nm sized pores, particularly 3-5 nm pores, in the polycrystalline secondary particles significantly decreased, thereby reducing the BET specific surface area.

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Anatase (TiO₂) has been paid attention as an environment-purification material due to its photocatalytic activity. In order to make use of anatase effectively, we designed to fix anatase particles in the porous structure of hydroxyapatite (HA) ceramics. We prepared anatase/HA composite granules by a hydrothermal method and evaluated the photocatalytic activity of the anatase/HA granules for environmental purification by examining the acetaldehyde decomposition. The anatase/HA granules were effective for the decomposition of acetaldehyde under the UV irradiation. These granules are expected to be useful for environmental purification.

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Layered perovskite Ca₃Ti₂O₇ codoped with Rh and Ln (Ca_3-xLn_xTi_1.9Rh_0.1O₇; Ln = La, Pr, Nd, Eu, Gd, Yb, and Y; 0 ≤ x ≤ 0.15) was synthesized by a conventional solid-state reaction to investigate the effects of Rh and Ln codoping on the photocatalytic activity. Rh and Ln-codoped Ca₃Ti₂O₇ exhibited a higher photocatalytic activity than Rh-doped Ca₃Ti₂O₇ for H₂ production from an aqueous methanol solution under visible light irradiation (λ > 420 nm). In addition, the induction period for H₂ production was shortened by codoping with Rh and Ln. The codoped elements helped control the oxidation state of Rh ions and suppressed the formation of oxygen defects, improving the activity of the Rh-doped Ca₃Ti₂O₇ photocatalyst.

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A reflux process was carried out for hybridization of aminopropyl-grafted mesoporous silica and metal cations at 110 and 140°C. For the sample hybridized with Fe²⁺, Co²⁺ and Ni²⁺, magnetite, Co₂(OH)₃Cl, and Ni₂(OH)₂CO₃·4H₂O particles of approx. 5-30 nm in diameter were formed. The amount of metal compounds was approx. 9-12 mol%. These compounds formed a porous aggregate on the outer surface of the mesoporous silica particles. For the hybrid with Fe²⁺ and Fe³⁺, magnetite approx. 3 nm in diameter formed not only on the outer surface but also within the mesopores derived from the mesoporous silica. The amount of magnetite achieved approx. 30 mol%. This hybrid shows an O₂ adsorption property three times as high as the other samples. These results demonstrate that nanoscale magnetite shows significant O₂ adsorption competence at room temperature.

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Strontium doped lanthanum manganite ((La_0.85Sr_0.15)_0.98MnO₃; LSM)/yttria-stabilized zirconia (YSZ) nanocomposite particles were synthesized through a novel co-precipitation method using YSZ nanoparticles with the average size of 3 nm as seed crystals. Phase evolution studies indicated that crystalline LSM/YSZ phases were obtained by calcining the co-precipitated precursor above 700°C. The nanocomposite particles calcined at 1000°C were screen printed on YSZ dense electrolytes and then sintered at 1100°C for cathode fabrication. The resulting cathode had a uniform porous structure consisting of fine grains ∼100 nm in size, and exhibited low polarization resistance of 2.82, 1.18, 0.48 and 0.25 Ω·cm² at 650, 700, 750 and 800°C, respectively under air atmosphere. These results indicated that the present nanostructured cathode may be applicable for intermediate temperature solid oxide fuel cells.

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K₃Ta₃B₂O₁₂ is photocatalyst that exhibit relatively high water splitting activity without co-catalyst, was synthesized by various solution methods. Obtained samples were characterized by X-ray diffraction. Samples synthesized by complex gelation method and polyamide-type polymerizable complex method ware single phase K₃Ta₃B₂O₁₂. Sample synthesized by complex gelation method was tested for water splitting activity, and this sample has little water splitting activity without co-catalyst. When NiO 0.5 wt% as co-catalyst was loaded to samples, hydrogen generated 1600 μmol/h.

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A chemical recycling method by using phase separation was applied to municipal waste slags. Glasses were prepared from incineration ash and ash-melted slag, where B₂O₃ was added to promote phase separation. The glasses were heat-treated at temperatures higher than their glass transition temperatures, and they were soaked in hydrochloric acid, leaching CaO, Fe₂O₃, K₂O, and S. Transparent and colorless solids containing ca. 80 mass% of SiO₂ were successfully obtained as residues. It was suggested that phase separation took place not in the heat-treatment but in the vitrification process, and further characterizations are however required to investigate the phenomena at microscopic levels in the recycling processes.

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Chromium removal and recovery from aqueous media which containing various concentration of Cr^VO₄^2- by hydrothermal mineralization treatment were investigated. Hydrothermal mineralizations with CaCl₃ or iron acetate as mineralizer enable effective removal of Cr from aqueous media and it could obtain CaCrO₄ or (Fe_0.6Cr_0.4)₂O₃ with very high concentration. Cr concentrations in the treated-water by both treatments were independent of the initial concentration of Cr. Additionally, the treatment using iron acetate could obtain Fe-Cr-O type natural mineral ((Fe_0.6Cr_0.4)₂O₃) which can be easily reused by industrial resource production system in existence. Thus, the hydrothermal mineralization treatment was one of the effective treatments for Cr removal from wastewater.

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Electrospun Al₂O₃-TiO₂ composite fibers were fabricated and characterized. Morphologies of the fibers after calcination at 500, 1000 and 1150°C, respectively, were examined by SEM, which showed that the diameters of the fibers decreased with increasing calcination temperature. XRD and TGA/DTA revealed that the Al₂O₃-TiO₂ fibers consisted of α-Al₂O₃ and rutile TiO₂ phases after calcination above 1150°C. FE-SEM images showed that the Al₂O₃-TiO₂ composite was consisted of both small round particles and large block-like ones, which were assigned as α-Al₂O₃ and rutile TiO₂ crystals, respectively. The Al₂O₃-TiO₂ fibers displayed a photocatalytic reaction to decompose acetaldehyde under UV irradiation.

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The thermal shock resistance of α-alumina porous capillary, the support material for hydrogen-permselective microporous ceramic membrane was studied. To study the effect of porosity on the thermal shock resistance systematically, porous alumina with different porosities was fabricated, and the thermal shock resistance of the fabricated samples as well as the porous capillary was estimated by the infrared radiation heating method. The mechanical and thermal properties concerned to the thermal shock resistance were also measured and the effect of the porosity on the properties was carefully examined. The fracture strength was not changed with temperature, but decreased with the porosity. The fracture toughness, Young's modulus and thermal conductivity were also decreased with porosity. Thermal shock resistance of porous alumina was estimated quantitively by the experimental thermal shock parameters, thermal shock strength, R_1c and thermal shock fracture toughness, R_2c. The thermal shock parameters of porous alumina were much lower than dense alumina, and decreased with porosity due to the decreasing of fracture strength and thermal conductivity. The experimental thermal shock strength was good accordance with that calculated from the material properties in this study. Thermal shock strength of porous alumina capillary at service temperature could be estimated by the comparison experimental and calculated thermal shock strength.

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Lithium nickel manganese oxides having 20% nickel excess and deficient with respect to the stoichiometric Li[Ni_1/2Mn_3/2]O₄ having a space group symmetry of P4₃32 were prepared and examined in nonaqueous lithium cells. Rechargeable capacity observed for the 20% nickel excess sample in voltage above 4.5 V is larger than that for the 20% nickel deficient sample. The effect of deviation from Ni/Mn stoichiometry from the ideal composition of Li[Ni_1/2Mn_3/2]O₄ upon the rechargeable capacity at 4.7 V is described in terms of the solid solution, phase separation, and superstructural Li[Ni_1/2Mn_3/2]O₄. From the results, the composition preferable to the five-volt lithium insertion material of Li[Ni_1/2Mn_3/2]O₄ is discussed. The cycling stability of Li[Ni_1/2Mn_3/2]O₄ in the cell with the Li[Li_1/3Ti_5/3]O₄-negative electrode is also examined in voltages ranging from 1.5 to 3.6 V at 25°C for 250 cycles and shown that the capacity fading of the cell is negligibly small below 4% even after 250 cycles.

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Mesoporous green tuff / tobermorite composites were synthesized by hydrothermal treatment of powder compacts consisting of waste green tuff and slaked lime. XRD results showed that chlorite, the mineral responsible for the green coloration of green tuff, remained after hydrothermal treatment. Tobermorite formed as a result of a reaction between the quartz inherent in green tuff and slaked lime. The formation of tobermorite led to an increase in bending strength, reaching 12 MPa after 10 h of hydrothermal treatment, as well as to an increase in specific surface area and mesopore volume. The composite adsorbed a greater quantity of water vapour and ammonia gas than waste green tuff.

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Source materials for carbon coating on LiMnPO₄ were examined to improve an electrochemical performance of LiMnPO₄. L-ascorbic acid, sucrose, polyethylene oxide (PEO), and carboxymethyl cellulose (CMC) were used as carbon sources for hydrothermal synthesis of carbon coated LiMnPO₄. Disordered (D) and graphite-like (G) carbons were detected by Raman spectroscopy for the prepared samples except for PEO-used one, and the highest G/D ratio was obtained for the sample prepared using CMC as carbon source. The electrochemical performance of the samples was evaluated by galvanostatic charge/discharge test. The carbon coated LiMnPO₄ prepared with CMC carbon source showed the highest discharge capacity, 94 mA h g^-1 at 0.01 C (corresponding to 55% of the theoretical capacity, 171 mA h g^-1), indicating that the carbon sources greatly influenced on the electrochemical performance of the carbon coated LiMnPO₄ prepared by the hydrothermal synthesis.

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Mg-Al LDH intercalated PtCl₄^2- anion (PtCl₄-LDH) was synthesized by a reconstruction method using potassium tetrachloroplatinate and its thermal changes were investigated at various temperatures. The PtCl₄-LDH included 17 mass% Pt was synthesized by a reconstruction method using K₂PtCl₄ solution of 10 mM to adjust the pH with NaOH to about 11. The obtained PtCl₄-LDH shows high crystallinity and has low content of CO₃^2-. The basal spacing of the obtained PtCl₄-LDH was 0.83 nm expanding slightly from 0.78 nm of starting LDH. The XRD patterns of the obtained PtCl₄-LDH showed that the second 00l diffraction line (006) became more accentuated than the first one (003) according to the intercalation of Pt components. Pt fine particles in the several nm were directly observed by TEM after firing at 500°C. However, the diffraction patterns of Pt or Pt components were not detected via XRD in the same sample. This is due to the coagulation of Pt components by the narrow basal spacing of the PtCl₄-LDH.

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The applicability of several nitride powders for use as foaming agents in superplastically foaming ceramics was investigated. Ceramic mono-foams were fabricated successfully using AlN and Si₃N₄ foaming agents. By using BN as a foam agent, on the other hand, we cannot fabricated well developed ceramic foams due to cracking and fracture. When the quantity of foaming agent was increased, the porosity increased to a certain amount, then saturated. With equal amounts of Si₃N₄, the porosity from the dispersed foaming agent was higher than that obtained from a monolithic compact without mixing, which was similar to the case of SiC foam agent.

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Mineral sepiolite (Mg₄Si₆O₁₅(OH)₂·6H₂O) with fibrous morphology is one of candidates for substituting asbestos. When sepiolite was used as a matrix of an inorganic insulator, it was expected that formation of cordierite (Mg₂Al₄Si₅O₁₈) at elevated temperatures should improve its thermal shock resistance. We investigated formation of α-cordierite by reacting two kinds of sepiolite (as-received and acid-treated sepiolite) with amorphous aluminosilicate fiber (Al₂O₃·1.88SiO₂), γ-alumina (Al₂O₃) and amorphous silica (SiO₂) at 1100-1300°C. A α-cordierite phase was observed above 1200°C for any starting compound, however, anorthite (CaAl₂Si₂O₈) was produced at 1300°C when as-received sepiolite which contained calcite (CaCO₃) as an impurity was used. A single phase of α-cordierite was prepared by heating the mixture of acid-treated sepiolite, amorphous aluminosilicate fiber and γ-alumina or acid-treated sepiolite, γ-alumina and amorphous silica at 1300°C.

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Chrysotile (Mg₃Si₂O₅(OH)₄) was treated hydrothermally in acid or alkaline hydroxide solution. By hydrothermal treatment in 1 M HCl, HNO₃ or H₂SO₄ solution at 180°C for 48 h chrysotile changed to amorphous silica by complete extraction of magnesium component and its fibrous morphology was held in spite of changing chemical composition. The maximum specific surface area (S_BET) of the fiberous amorphous silica was 127 m²/g. It was converted to Mg(OH)₂ by complete dissolution removal of silica component in 20 M NaOH or KOH solution at 180°C for 48 h and the fiberous morphology of chrysotile disappeared.

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Clay/poly(methyl metacrylate) (PMMA) organic-inorganic hybrid gas barrier layers on PP were prepared by photopolymerization. The effects of clay content on the oxygen barrier property and surface hardness of the films were investigated. Oxygen permeability coefficients of the hybrid layer was small and about eight times higher than that of poly(vinylidene chloride) (PVDC) and water vapor transmission rate of the hybrid layer was the same order of PVDC. Pencil hardnesses (50 g load) of the PP with the hybrid layers were more than B. These values were considerably higher than that of PP (6B). These properties were thought to be due to well dispersion of inorganic segments (clay) and organic segments (PMMA) in the hybrid. From the results, it was found that the organic-inorganic hybrids could be applicable to gas barrier films.

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The formation of thin tri-layers of Sr- and Mg-doped lanthanum gallate (LSGM) and Gd-doped ceria (GDC) solid electrolytes was performed by electrophoretic deposition (EPD) on a Ni-YSZ anode for use in solid oxide fuel cell (SOFC) applications. The surface of the NiO-YSZ substrate was coated with a conductive polypyrrole to provide electric conduction, which is essential for the EPD processing. The GDC/LSGM8282/GDC laminar coating was performed by sequential deposition on the same substrate. The electrolyte layers were easily sintered together on the anode without cracking and peering-off at the interfaces.

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Tolerance factor controlled Mn-based colossal magnetoresistance (CMR) thin films (La_0.7Ca_0.3MnO₃, La_0.7Sr_0.3MnO₃, La_0.7Sr_0.11Ba_0.19MnO₃, and La_0.7Ba_0.3MnO₃) which have the same content of divalent cation and Mn³⁺/Mn⁴⁺ ratio were deposited on amorphous SiO₂/Si substrate by rf magnetron sputtering at 350°C substrate temperature. Post annealing treatment for 1 h at 600°C was also carried out to investigate the effects of internal strain and chemical bonding nature from different divalent ions on the electrical properties of the films by maintaining a similar crystalline state. The films crystallized with pseudo cubic structure in spite of different tolerance factors. The sheet resistance of films changed according to crystallization and Mn-O bonding character. Mn L-edge X-ray absorption spectra revealed that Mn³⁺/Mn⁴⁺ ratio did not change in all the films and Mn 2p core level X-ray photoelectron spectra showed that Mn-O bonding property changed to more covalence as increasing tolerance factor by substitution with larger size divalent cation. O K-edge X-ray absorption spectra observed t_2g and e_g electron states and low resistivity after post anneal could be explained by the promotion of electrons to low binding energy state. Temperature coefficient of resistance (TCR) values were about -2.24 ∼ -2.57%/K of as deposited CMR films and these values were reasonable for uncooled microbolometer applications.

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Effects of Ca_0.61Nd_0.26TiO₃ (CNT) addition on crystal structure and microwave dielectric properties of Ba₄Nd_9.33Ti₁₈O₅₄ (BNT) ceramics had been investigated. Only tungsten bronze type phase was formed when CNT addition (x) was less than 0.4. While, a secondary phase Nd₂Ti₂O₇ was observed when 0.4 ≤ x ≤ 0.8. As CNT addition increasing, the dielectric constant increased steadily, and temperature coefficient of resonant frequency had less change. Qf value firstly increased sightly, and decreased gently with further increase of CNT addition. The BNT ceramics exhibited high ε (∼80), high Qf value (> 9000 GHz) and relative low temperature coefficient (∼50 ppm/°C) when CNT addition (x) was not beyond 0.4. The relationships between the crystal structure, tolerance factor and microwave dielectric properties had been also discussed.

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The present work highlights the microstructural features and mechanical properties of Y₂O₃ prepared with and without Yb³⁺ doping that processed through combustion synthesis involving various organic fuels such as urea, citric acid and glycine. Properties such as powder-flow, particle packing, green density, % of shrinkage, sintered density, grain size, Vicker's microhardness (H_v) and fracture toughness (K_IC) were analyzed and compared with respect to the fuel sources. The as combusted precursors were calcined at 1100°C for 4 h under oxygen atmosphere to obtain fully crystalline Y₂O₃ powders. Cylindrical pellets were fabricated as test specimens and sintered at 1600°C for 3 h. The SEM images of the sintered yttria samples show an average grain size of < 3 μm irrespective of the fuels. However, the mechanical properties show significant dependence on the fuels used. A maximum hardness of 6.8 ± 0.1 and 7.0 ± 0.1 GPa was obtained for Y₂O₃ and Yb³⁺ doped Y₂O₃ derived from glycine fuel. Whereas the maximum fracture toughness of 2.6 ± 0.3 MPa m^1/2 was obtained for the samples derived from urea. The Yb³⁺ doping found to increase the bulk hardness of yttria from 0.2 to 0.6 GPa. The study contributes to appropriately select the fuels for obtaining high dense, mechanically stable yttria ceramics through combustion process.

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Aluminum (Al) doped zinc oxide (ZnO) thin films have been prepared using sol-gel spin-coating method at various doping concentrations. The thin films were characterized using UV-Vis-NIR spectrophotometer and current-voltage (I-V) measurement system for optical and electrical properties respectively. The results show all films exhibit low absorbance in visible and near infrared (NIR) region. The calculated Urbach energy indicated the defects in the thin films increase with doping concentrations. The electrical properties of Al doped ZnO thin films improved with Al doping as measured through I-V measurement system.

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An aurivillius phase Layered perovskite Bi₅FeTi₃O₁₅ system was synthesized for first time by the solid-state reaction method yielding a single phase Bi₅FeTi₃O₁₅ at only 1030°C. The electronic band structure and optical properties as well as the crystallization behavior of the materials were studied by using UV-DRS and XRD. The as-prepared particles those were the agglomerates of 25 nm crystals, exhibited the band gap of 2.38 eV (525 nm). Their visible light (λ ≥ 420 nm) photocatalytic activity as studied by the photo-decomposition of isopropyl alcohol (IPA) was found to be much higher than that of well-known TiO_2-xN_x photocatalyst.

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Various glasses with different compositions (50 - 2x)ZnO-xBi₂O₃-(50 + x)P₂O₅ (x = 0-20 mol%) were prepared. This study examined the effect of the structure and properties in phosphate glass system according to the change in Bi₂O₃ content in ZnO-Bi₂O₃-P₂O₅ glass. The structure of the glasses was analyzed by Fourier transform infrared (FT-IR) analysis. The FTIR spectra were recorded in the spectral range from 400 to 1400 cm^-1. The structural investigations based on these spectra showed the rapid depolymerization of the phosphate chains with increasing Bi₂O₃ content along with the formation of P-O-Bi bonds. The density, glass transition temperature (T_g), molar volume and optical properties of the glasses were determined from the structural changes in the glasses. T_g, density and molar volume increased with increasing in Bi₂O₃ content in the glass. The optical absorption edge (λ_cut-off) and optical band gap (E_g) were determined from the optical transmittance spectra of the polished samples recorded at room temperature, and found to be associated with structural changes occurring in these glasses with increasing Bi₂O₃ content.

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Carbon-glass composite powders were directly prepared by spray pyrolysis from spray solution containing nano-sized carbon black powders and dissolved Pb-based glass components. The composite powders had spherical shape and non-aggregation characteristics. One composite particle was formed from one droplet. The mean size of the composite powders measured from the SEM images was 0.7 μm. Carbon black powders were well dispersed inside the matrix of glass. The black matrix layers formed from the carbon-glass composite powders had smooth surfaces at firing temperatures of 500 and 550°C. The black matrix layers formed from the paste with carbon-glass composite powders had lower transmittances than those formed from the paste with carbon black and glass powders under ultraviolet and visible light range. The reflectances of the black matrix layers formed from the paste with carbon-glass composite powders were 3.1 and 4.3% at firing temperatures of 500 and 550°C.

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Transparent, polycrystalline MgAl₂O₄ ceramics have been fabricated by sintering optimized-configuration, powder compacts formed from a material prepared by flame spray pyrolysis. Transparent parts (80% light transmission at 2 mm thickness) could be obtained after pressureless sintering in air at 1280°C/3 h, followed by hot isostatic pressing at 1320°C/3 h/200 MPa. The average grain size was 0.45 μm. Such materials exhibit property combinations suitable for transparent armor applications.

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