Recent rare earth minerals discovery, distribution and production are introduced. Next, the characteristics of rare earth minerals and mineral processing techniques are discussed. Also the recycling technologies related on materials containing rare earth elements, that is, decomposition of magnet, fine particle separation in fluorescent lamp, selective precipitation and solvent extraction of spent optical glass are described.

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We synthesized polycrystalline Pr³⁺-doped perovskites La_1/3MO₃: Pr³⁺ (M = Nb, Ta), and investigated their crystal structure, optical absorption and luminescence properties. The optical band gap of La_1/3NbO₃ is smaller than that of La_1/3TaO₃, which is primarily due to the difference in electronegativity between Nb and Ta. In La_1/3NbO₃: Pr³⁺, the red emission assigned to the f-f transition of Pr³⁺ (¹D₂ to ³H₄ ) upon band gap photo-excitation was observed, whereas the f-f transition of Pr³⁺ with blue-green emission (³P₀ to ³H₄ ) was quenched. On the other hand, in La_1/3TaO₃: Pr³⁺, the blue-green emission upon band gap photo-excitation was observed. Their differences in emission behavior are attributed to the energy level of the ground and excited states of 4f² for Pr³⁺, relative to the energy levels of the conduction and valence bands, and the trapped electron state which mediates the relaxation of electron from the conduction band to the excited state of Pr³⁺.

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Barium titanate (BTO) particles in the size range from 10 nm to 150 nm have been developed using hydrothermal synthesis with the control range of 10nm. The particles have an optimized morphology and narrow particle size distribution, both of which seems to be contributed to the dispersion of the green sheets in the multi-layer ceramic chip capacitors (MLCCs) that contain these particles. Although these nano-sized BTO are not still spread into the market, it is considered that these are used for the dielectric thin films, the PDF devices, and the piezoelectric devices. The powder properties intend to be improved to optimized with maintaining the advantages of the nano-size and dispersion.

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Nanoparticle synthesis in supercritical water (around 374^oC and 22MPa) was extensively investigated because good crystallization of products can be obtained in high efficacy. Corrosion of reactor materials and aggregation of nanoparticles in supercritical water, however, were often found as main problems. Using mixtures of water and organic solvents significantly decreased the critical temperature (Tc) and pressure (Pc) of the medium to as low as about 550-650 K and 7-20 MPa, respectively. The effects on preparing BaTiO₃ nanoparticles in supercritical state of mixing solvents were discussed.

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Shell waste from the aquaculture industry is a problem in many countries, including New Zealand and Japan. To a ceramic engineer this material is a renewable and cheap source of calcium carbonate that through smart processing can be turned into other usable and potentially more valuable ceramic products. This work will describe research carried out to investigate the use of waste mussel shells for the production of hydroxyapatite (HA). The potential for the production of HA by both wet and dry processing routes will be described

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In this contribution, "mixed anion compounds" consisting of same or different group of elements, as practically prepared up to date, were extracted as the samples, and some unique points of the synthesis processes or conditions and structural characteristics were discussed on them as well as the physical properties on the basis of the nature of chemical bonding between a series of cationic and anionic elements, so that the possible material design for new compounds or phases of mixed anions was made.

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We have been successful in perovskite-type oxyfluorides, BaFeO₂F, SrFeO₂F, BaInO₂F, PbScO₂F, PbFeO₂F and investigated their crystal structure. As a result, all compounds except for PbFeO₂F have cubic structure, even though their tolerance factor are not equal to 1. On the other hands, it is indicated that Mn-containing oxyflurides, PbMnO₂F, SrMnO₂F, Sr(Mn_1/2Ga_1/2)O₂F, have tetragonal structure. In this study, we try to prepare high purity SrMnO₂F, Sr(Mn_1/2Ga_1/2)O₂F and investigates the crystal structure.

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The new photocatalysts have been obtained by coupling SrTi_1-xCr_xO_3-y with Sr₄Al₁₄O₂₅:(Eu, Dy). Sr₄Al₁₄O₂₅:(Eu, Dy) with eye-visible persistent luminescence can be used as a light source after a promising coupling. The obtained Sr₄Al₁₄O₂₅:(Eu, Dy)/SrTi_1-xCr_xO_3-y catalysts were found to persistently reduce NO in the dark after turning off the solar light irradiation, while the photocatalytic activity of unsupported SrTi_1-xCr_xO_3-y immediately disappeared.

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Recent developments in materials design, luminescence and applications of silicon-based oxynitride phosphors, or sialons, are reviewed. The structures of crosslinking (Si,Al)-(O,N)₄ tetradedra in oxynitride phosphors increase the covalent properteis, and have an excitation band of visible-light range. The structural versatility of oxynitride phosphors makes it possible to attain the emission colors of blue, green, yellow, and red; thus they are suitable for use in white LEDs.

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Scanning transmission electron microscopy is used to characterize atomic structures of heterointerface between Platinum nanoparticles and MgO (100) surface. Platinum single atoms and nanoclusters with different size on MgO (100) surface are clearly imaged, although it is difficult to distinguish platinum atoms bond to Mg or O atoms. It is also found that the shape of Platinum nanoclusters change during observation, indicating that Platinum may not strongly attach to MgO surface. We believe that characterization of the interface structure will be seminal in understanding the origin of catalytic activity of Platinum nanoparticles supported on MgO.

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Atomic structures of energy storage and intelligent materials are related to the functional properties. Spatial resolution of the transmission electron microscopy has been drastically improved by the development of a spherical aberration corrector. So far, annular dark field scanning transmission electron microscopy (ADF-STEM) has been applied to observe the atomic columns in the crystalline materials, but this method is not able to view the light element. On the other hand, annular bright field STEM (ABF-STEM) technique is able to view the light element, such as oxygen, nitrogen and lithium. In this study, hydrogen atomic columns in the several metal hydrides were tried to be observed by ABF-STEM technique.

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The microstructural characterization of a GdBa2Cu3Oy (GdBCO) layer fabricated by in-plume PLD method was performed by TEM and an FIB-SEM dual beam system. Numerous outer-growth grains form on the GdBCO surface. These grains were identified by electron beam diffraction. In addition, a 3D reconstructed image of the GdBCO layer using the FIB-SEM dual-beam system clearly shows the distribution of those outer-growth grains.

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The Ruddlesden-Popper phase Sr₂FeO₄ was reduced to Sr₂FeO₃ using calcium hydride as a low temperature powerful reducing agent. In the resulting framework, FeO4 square planes form chains that run parallel to each other. The structure and magnetism of the novel Sr₂FeO₃ will be compared to the infinite layer SrFeO₂ and spin-ladder Sr₃Fe₂O₅ compounds that also possess iron in an oxygen square planar coordination.

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Non-stoichiometric oxides which store/release oxygen reversibly at moderate temperatures are called "oxygen-storage materials (=OSMs)". OSMs may be applicable to various high-temperature applications such as oxygen separation, oxygen enrichment, redox catalysts, etc., hence contributing to the improved productivity and environmental protection. To realize such applications, novel OSMs with remarkable oxygen storage capability are highly desirable. We focused on oxygen-deficient perovskite manganese oxides and developed two candidates for high-performance OSMs, i.e., BaYMn₂O_5+d and Ca₂(Al_xMn_1-x)₂O_5+d. In this presentation, remarkable oxygen storage capabilities of these manganese oxides are demonstrated. Also, possible future uses for oxidizing agent and oxygen enrichment are discussed.

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Novel oxyfluoride Bi₂PdO₄F_0.5 was synthesized by anion intercalation. XRD pattern of the product could be indexed using the same space group (P4/ncc) as Bi₂PdO₄. Although Bi₂PdO₄ shows no magnetic moment, Curie-Weiss behavior was observed in fluorinated samples. The observed spin is probably derived from Pd ions. Palladium in an oxidation state between two and four tends to disproportionate into Pd²⁺ and Pd⁴⁺. Since Pd²⁺ and Pd⁴⁺ do not have spin, the observed spin moment in Bi₂PdO₄F_0.5 means that the Pd ions are in a higher valence state, without such disproponation.

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