Teaching materials characterization to support student research projects requires a systematic educational approach, because characterization involves a combination of analysis instruments. As analytical instruments are expensive, it is difficult to provide multiple sets simultaneously. An effective educational program allows students to select their own research materials to characterize and apply their personal strategies of instrumental analysis. These strategies are designed around the purposes of the analytical instruments, e.g., molecular structure analysis, crystal structure analysis, morphology assessment, surface analysis, elemental analysis, and thermal analysis. An open-ended laboratory complements this educational purpose. Here, we report on an open-ended laboratory program for fourth-year undergraduate and graduate students at the Materials Characterization Central Laboratory at Waseda University (Tokyo, Japan). The goals of our open-ended laboratory program are to enable students to (1) conduct instrumental analysis, (2) operate analytical instruments, and (3) interpret their data. A team led by a supervisor and laboratory staff offers students a flexible program. This flexibility can be applied to various research fields, such as macromolecular chemistry, inorganic chemistry, organic chemistry, physical chemistry, electrochemistry, physics, catalyst chemistry, biomaterials science, and chemical engineering. These diverse research fields demonstrate the feasibility of applying our open-ended laboratory program to student research projects.

The general formula of a phase relation between well-known bismuth layer-structured ferroelectrics (BLSF) such as Bi3TiNbO9, Na0.5Bi2.5Nb2O9, Bi4Ti3O12, and Na0.5Bi4.5Ti4O15 including perovskite compounds (Bi0.5Na0.5) TiO3 and NaNbO3, that is, Na(m-3+x)/2 Bi(m+5-x)/2 Ti m-x Nb x O3m+3 (2≤m≤5), was discussed to form the layer structure with the numbers m=3, 4 and 5 of layer, where x is the number of Nb ions in the layer structure and 1≤x≤2 for m=2 and 0≤x≤m for 3≤m≤5. A new BLSF series is found for m=3 and x=1, 2 and 3. The ferroelectricity for m=4 (x=3 and 4) was very weak and no single phase with m=5 was obtained.

Photoreduction of Cu2+ ions to Cu metal by titanium(IV) oxide (TiO2) was conducted in the presence of a silica–surfactant hybrid under sulfuric acid conditions. After irradiation, a dark-red color, reflections due to Cu metal in the X-ray diffraction pattern, and peaks due to Cu 2p1/2 and 2p3/2 in the X-ray photoelectron spectrum indicated the precipitation of Cu metal in the product. In addition, an increase in the Brunauer–Emmett–Teller specific surface area from 36 and 45 m2/g for the silica–surfactant and TiO2, respectively, to 591 m2/g for the product, and a decrease in the intensity of the C-H stretching band in the Fourier–transform infra-red spectra implied the removal of surfactant during the reaction. These characteristics were never observed when TiO2 was used solely. Therefore, this study indicated that the photoreduction of Cu2+ ions to Cu metal by TiO2 was facilitated under the sulfuric acid medium, where the surfactants extracted from silica–surfactant hybrids by protons in the acidic condition were successfully photo-oxidized by TiO2. Thus, this study presents a new application of the conversion of a silica–surfactant hybrid into mesoporous silicas.

No abstract

A testing procedure was proposed to study water movement in compacted bentonite and the development of swelling pressure (ps) when compacted bentonite specimens were wetted. In this procedure, a multi-ring mold was introduced for ps measurements, after which the specimen was sliced for X-ray diffraction to find movement of water in the interlayer space of montmorillonite. Results revealed a relation between four phases of ps development and evolution of four states of interlayer water molecule arrangement of montmorillonite (L): when ps reached its first peak in phase I, L moved from 1 row water arrangement (1w) to at least 2w; when ps decreased and re-increased in phases II or III, L moved from 2w to at least 3w; and when ps reached a steady state in phase IV, L = 3w. The w distribution in the compacted bentonite was also measured as water absorption time increased. Based on those results, the global water movement was estimated in terms of diffusivity (D) following a method employing Boltzmann transform. Results of comparisons implied that D calculated using this method matched experimental data well and the method was rather easily handled.