A thin film of Bi₄Ti₃O₁₂ was prepared from a layered assembly by alternative spin-coating of a sol-gel solution and a Bi₄Ti₃O₁₂ seed suspension on a glass substrate. The layered assembly was heated at various temperatures and the crystallization behavior was studied. For comparison the thin film of Bi₄Ti₃O₁₂ was also prepared from a spin-coated sol-gel solution without the seed crystal. In case of the layered assembly with seed crystal Bi₄Ti₃O₁₂ was crystallized at 450°C, while without the seed crystal Bi₄Ti₃O₁₂ was not crystallized at the same temperature. Without the seed crystal, higher temperature was required for the crystallization and pyrochlore phase was also observed. Higher temperature led a reaction between the spin-coated layer and the glass substrate, causing a deterioration of the substrates. Formation of thin film of Bi₄Ti₃O₁₂ crystal at temperatures below 450°C is required for the LSI fabrication, and the process developed in this study meets such requirements.

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For the purpose of recovering calcium resource, an attempt was made to extract Ca²⁺ by carbonation reaction from the calcium-based wastes such as limestone slurry, concrete waste and steel slag, and then the desulfurization characteristics of the Ca²⁺ extracts obtained from these calcium-based wastes were investigated. The Ca²⁺ extraction experiment was carried out in a hermetic vessel under the CO₂ pressure range of 0.10-2.00 MPa at the temperature range of 280-333 K.
As a result, it was found that Ca²⁺ extraction behaviors of limestone sludge and concrete waste were similar to that of limestone. However, the rate of Ca²⁺ extraction from steel slag was about one-third of those from the other calcium-based wastes. By introducing SO₂ gas (1000 cm³·m^-3) into the Ca²⁺ extract, it was found that SO₂ absorption performance of the Ca²⁺ extract of the calcium-based waste employed was almost the same to that of limestone slurry.

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The removal behaviors of Mg-Fe-Al-C1 form Hydrotalcite (HT) Mg_0.666Fe (III) _0.162 Al_0.172 (OH) ₂Cl_0.140 (CO₃) _0.0121·0.328H₂O, with three kinds of metal ions for phosphate and nitrate ions were studied fundamentally and the possibility of the simultaneous removal of nitrogen and phosphorus was estimated. Maximum removal amounts of Mg-Fe-Al-Cl-HT for phosphate and nitrate ions were 73.9 mg P·g^-1 and 16.6 mg N·g^-1, respectively. Mg-Fe-Al-Cl-HT had high removal capacity for phosphate ion in the wide range of initial pH from 2 to 9. Depending on the pH, the phosphorus removal mechanism of Mg-Fe-Al-CI-HT was divided into three regions; coagulative precipitation at pH 2, coagulative precipitation and ion exchange in the slightly acidic and neutral regions of pH and ion exchange in the weakly alkaline condition. The anion selectivity of Mg-Fe-Al-Cl-HT in the single-anion solutions was in order of CO₃^2->>SO₄^2->PO₄^3->Cl^->NO₂^-≥NO₃^- and was changed in the mixed-anions solution as PO₄^3->CO₃^2->SO₄^2->Cl^->NO₃^->NO₂^-. The selectivity for phosphate ion became highest in the mixed-anions solution. Mg-Fe-Al-CI-HT was able to effectively remove phosphate ion in the secondary treated wastewater from the private sewage system, while nitrate ion was scarcely removed.

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A method to estimate compositional fluctuation in (Ti_1-x, Zr_x) B₂ system using a value of the width of the fluctuation of lattice spacing was developed. This system forms a complete solid solution. All the compositions have hexagonal symmetry. The fluctuations of lattice spacings of (hk·0) planes and (00·l) planes have different values, because the dependencies of a-spacing and c-spacing on the composition are different. The compositional fluctuation was determined from the measured values of the fluctuation of the lattice spacings. Effect of the mechanical strain on the determination of the compositional fluctuation was examined, because the mechanical strain also affects the measured values of the fluctuation of lattice spacings. The examination showed that the mechanical strain can be neglected in this measurement. Relation between measured compositional fluctuation and composition showed that (Ti_0.5Zr_0.5) O₃ had largest compositional fluctuation for samples prepared under the same conditions. (Ti_1-x, Zr_x) B₂ by spark plasma sintering had smaller compositional fluctuation compared with those by hot press sintering.

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The synthesis of similar compounds to Ca₂Eu₈ (SiO₄) ₆O₂ in MO-SiO₂-Ln₂O₃ (M = Ca, Sr, Ba, Ln = lanthanide) system were investigated and their luminescent properties were studied. In MO- SiO₂-Eu₂O₃ system, it existed in one phase area of the compound that took the apatite structure. This compound was shown by M_mEu_n (SiO₄) ₆O_x (2m=12-n, x=n-6). The range of composition of this compound was 6-9 as n in all alkaline earth system. The emission intensity has changed greatly though the same structure is taken in this composition area. The possibility of existence of compound M₂Ln₈ (SiO₄) ₆O₂ was examined. As a result, the same crystal structure was formed with all lanthanide elements in the Ca system and the lanthanide elements without Yb in the Sr system. This compound of the apatite structure possesses the high stability of a crystal structure for the kind and the composition change of the element, and seems for the possibility with an interesting characteristic to exist like this by variously examining the kind of the element and the amount.

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This study was made to investigate about quantity of organic and inorganic component in coccolithophorid algae incubated with normal culture medium and culture medium including many Ca²⁺ ion. A lot of included fatty acid was cerotic acid in each culture medium. However, quantity of unsaturated fatty acid such as docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and linoleic acid increased by incubating coccolithophorid algae in culture medium including many Ca²⁺ ion. The essential amino acids such as methionine and phenylalanine were included in the cell of coccolithophorid algae. The acid saccharides were detected a lot in coccolithophorid algae culture medium including many Ca²⁺ ion. The coccolithophorid algae incubated in culture medium including many Ca²⁺ ion included a lot of calcium carbonate, fatty acid and saccharides.

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