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A novel recycling system for indium in indium tin oxide (ITO), which comprises the dissolution of indium oxide (In2O3), chlorination, chelation, and steaming treatment, was established. Indium trichloride (InCl3) was quantitatively synthesized by the reaction of In2O3 with hydrochloric acid (HCl) and furnished tris(ethyl acetoacetato)indium (In(etac)3) in a high yield by a subsequent reaction with ethyl acetoacetate (Hetac). In(etac)3 was mixed with bis(acetylacetonato)tin dichloride (Sn(acac)2Cl2) and spin coated on a glass plate, followed by steaming and heating to obtain ITO films containing 10 wt% tin oxide. In2O3 was crystallized in c-, rh-, and o-In2O3. This film showed a resistivity of 9.7 Ωcm and a transparency of 86%.

Recently, our group synthesized perovskite-type oxide ABO3 (A = Sr, Ba; B = Ti, Zr) with high crystallinity simply by leaving a powder mixture of A(OH)2•nH2O and BO2 hydrous gel at room temperature...

Ti-doped ZrO2 is a chemically stable and persistent luminescence material. Doping and co-doping is an effective approach for improving the afterglow properties of phosphors, but few studies have investigated the co-doping of ZrO2:Ti systems. This study aimed to synthesize ZrO2:Ti, M (M = Ca2+, Y3+, Ti single-doped, Nb5+, W6+) and evaluate the luminescent properties of the resulting materials, with a specific focus on the relationship between trap depth and the valence state of the co-doped cation. The ratio of the luminescent center to co-doped ion was optimized using the combinatorial approach, where 0.09 mol % Ti led to the best afterglow duration. The emission decay curves of each co-doped sample differed significantly, where a change in curvature was observed in the Ti single-doped and W6+ co-doped samples due to the presence of multiple traps. From the thermoluminescence glow curves, the trap originating in an oxygen vacancy with a peak at around 270 K was observed. The trap depth was dependent on electrostatic interactions between the trapped electrons and their surrounding cations, and thus related to the valence of the co-dopant. Overall, co-doping with high-valent cations led to improved afterglow duration.

We propose a new direct anodic electrodeposition process for carbon coatings that is possible at room temperature in ionic liquid (IL) with phenylsilane derivatives, which include dimethylphenylsil...

Metal oxide semiconductor gas sensors have been widely studied for the selective detection of various gases with trace concentrations. The identification of the reaction scheme governing the gas sensing response is crucial for further development; however, the mechanism of ethanol (EtOH) gas sensing by ZnO is still controversial despite being one of the most intensively studied target gas and sensing material combinations. In this work, for the first time, the detailed mechanism of EtOH sensing by ZnO is studied by using a bulk single-crystalline substrate, which has a well-defined stoichiometry and atomic arrangement, as the sensing material. The sensing response is substantial on the ZnO substrate even with a millimeter-size thickness, and it becomes larger with resistance of the substrate. The large sensing response is described in terms of the adsorption/desorption of the oxygen species on the substrate surface, namely, oxygen ionosorption. The valence state of the ionosorbed oxygen involved in EtOH sensing is identified to be O2– regardless of the temperature. The increase in the sensing response with the temperature is attributed to the enhanced oxidation rate of the EtOH molecule on the surface as analyzed by pulsed-jet temperature-programmed desorption mass spectrometry, which has been newly developed for analyzing surface reactions in simulated working conditions.

Hydrogen gas is a promising, clean, and highly efficient energy source. However, to use combustible H

This study reports a design of a variety of nanostructured films of 2D oxide nanosheets. We systematically examined the deposition of perovskite-type Ca2Nb3O10- nanosheets by spin-coating their dimethyl sulfoxide dispersion. Neat and homogeneous monolayer tiling was attained on various substrates by selecting an optimum rotation speed, which was dependent on the nanosheet concentration. Repeating the optimized spin-coating process allowed for layer-by-layer deposition of the nanosheets into multilayer films with a designed layer number. Vertical superlattice heterostructures could also be assembled by alternately spin-coating the suspensions of Ca2Nb3O10- and Ti0.87O20.52- nanosheets. Furthermore, spin-coating of a mixed suspension of Ca2Nb3O10- and Ti0.87O20.52- nanosheets led to a mixed mosaic-like monolayer of these two nanosheets. The present study thus demonstrated spin-coating as a facile and powerful route to construct various nanostructures based on 2D oxide nanosheets.

In recent years, "Materials Genome Initiative (MGI)", "Materials Informatics (MI)", and "Process Informatics (PI)" research have attracted much attention as keywords for high-throughput materials discovery. Much of the MI and PI research that has been published so far emphasizes data mining, statistics, machine learning, and predictive analytics. The MGI proposed by the US government in 2011 indicated that material innovation requires "experimental tools" in addition to "computational tools" and "digital data. "Experimental tools" means the creation of big data using automated high-throughput synthesis, evaluation and analysis systems, but there are not many examples of this development. In order to promote highly accurate materials discovery, a three-way relationship is important. And in order to improve the overall speed of exploration, all processes need to be accelerated. In the production of ceramic powder, which is also the synthesis process of dielectrics, the crystalline phase and grain size vary depending on the raw material manufacturer, purity, sintering atmosphere, sintering temperature, and other conditions. These have a great impact on the physical properties. It is important to create a data set that includes not only composition, phase identification results, lattice parameters, and physical property data, but also detailed experimental process conditions. If the data can be collected in a unified high-throughput experimental environment, it will greatly contribute to data interpolation in MI and PI research. We expect that combining the data obtained from high-throughput automated experiments with the data-driven research found in MI and PI will accelerate more accurate research. To achieve this goal, we are continuing to work on the development of combinatorial technology, a high-throughput synthesis, evaluation, and analysis technique for multi-component ceramic powders. For the preparation of powder samples consisting of a vast number of combinations, we have developed two methods based on wet processes.1)2) These devices allow us to synthesize 100 samples per day, reducing the amount of raw material used per sample to about 1/1000. This has the advantage of not only increasing the high-throughput but also reducing the excessive use of raw materials. After the library is created, the crystal structure needs to be evaluated. In recent years, the high-speed detectors of experimental X-ray diffractometers have made it possible to obtain X-ray diffraction patterns in a short time. In 2014, Gregoire et al. developed a technique to simultaneously collect synchrotron XRD and XRF data for a group of multi-component thin film samples. They developed a technique to collect the data and showed that they could collect at least 5000 patterns per day in less than 18 seconds per sample3). Furthermore, Kusune et al. matched the synchrotron thin-film XRD patterns with the Inorganic Crystal Structure Database (ICSD) using an on-the-fly method, and greatly improved the classification accuracy of structural phases overlapping in the three-component reaction diagram.4) The use of XRD patterns for informatics is often discussed between phase information, lattice constants and physical properties, but crystallographic information such as fractional coordinates should be added to the data set if genomic machine learning is to be promoted. In order to obtain the diffraction intensities for high-throughput synthesized samples, which are necessary for structural refinement, collaboration with synchrotron radiation is required. We propose a high-throughput crystallographic information collection process combined with efficient measurement tools and an automated structure refinement program.5,6) 1) K. Fujimoto et al., Measurement Science and Technology 16 41-45 (2005). 2) K. Fujimoto et al., Solid State Ionics 177 2639-2642 (2006). 3) J. M. Gregoire et al., Journal of Synchrotron Radiation, 21(6), 1262-1268 (2014). 4) Aaron Gilad Kusne et al., Scientific Report, 4: 6367 (2014). 5) A. Aimi et al., ACS Combinatorial Science 22(1) 35-41 (2020). 6) K. Fujimoto et al., ACS Combinatorial Science 22(12) 734-737 (2020).

Ti-doped ZrO

We propose to minimize the sampling time for high-throughput measurements of powder X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) in synchrotron radiation. The conventional synchrotron radiation powder X-ray diffraction method requires filling of a capillary tube, but a structure-refining diffraction pattern could be obtained by transferring the crushed powder to a tape and rotating the cassette-tape tool by ±5° around the sample position. XAFS spectra could also be measured with the sample attached to the tape. The time required for sample preparation was greatly reduced, which made high-throughput experiments with powders in synchrotron radiation experiments more accessible.

Camphorsulfonic acid (CSA)-doped polyaniline (PANI) and thermally reduced graphene (TRGO) composite polymer film with high thermoelectric (TE) properties were fabricated. We developed a modified Hummers method with an additional ultrasonic disruption technique to obtain well-isolated TRGO powder and well-dispersed PANI–CSA–TRGO composite polymer. Transmission electron microscope (TEM) observation, electron energy-loss spectroscopy, and Fourier transform infrared spectroscopy analyses revealed that the ultrasonic disruption process produced a well-isolated state of graphene oxide, and this state remained after a thermal reduction process. The dispersed TRGO powder was added to CSA-doped PANI composite polymer to improve its electrical conductivity (EC) properties. Addition of the well-isolated TRGO powder with high crystallinity resulted in remarkable improvement in EC without any degradation of the Seebeck coefficient (SC), which is representative of TE properties. The highest SC and EC values obtained in this study were 24 μV K−1 and 3677 S cm−1, respectively, which were observed for the 30 wt% TRGO-added PANI–CSA composite film, and the resulting power factor reached 214 μW mK−2. Well-isolated graphene with high crystallinity was fabricated using an additional ultrasonic disruption process, and well-dispersed polymer/graphene composite was also fabricated using the same sonication process. This optimized sonication process is simple but effective for improving TE properties of the composite.

Automated structural analysis techniques are required to accelerate materials research. In this study, we developed an algorithm to automate Rietveld analysis, which is a method for crystal structure refinement using powder diffraction patterns. This algorithm features the repeated generation of a set of initial values, followed by one-shot refinement. Accurate results were obtained without any strategy for the sequence of refinement, as is often used in manual analysis. Implementation and testing of the automated algorithm provided fitting results that were comparable to those of manual analysis, even when inaccurate initial values for structural parameters were input. Moreover, the much shorter time was required for the developed automatic analysis method than for manual analysis. The developed method will likely facilitate the analysis of large amounts of diffraction data, allowing the accumulation of structural data that can enhance the efficacy of materials research.

Cr-doped higher manganese silicides (HMSs) (Mn1-xCrx)Si1.75 (x = 0–0.35) have been prepared by repeated sintering from raw elemental powder using spark plasma sintering. The a- and cMn-axis length increases with increasing Cr content x. The results of powder X-ray diffraction and microstructural observation suggest that impurity phases, e.g. (Mn, Cr)Si and CrSi2, exist in the samples with x = 0.20 or above. The electrical resistivities and Seebeck coefficient decrease with increasing Cr content x. The Cr content x of 0.10 indicated the largest power factor at 850 K (1.39×10-3W/mK), followed in order by x of 0.25, 0, 0.05, 0.15, 0.20. To confirm the effect of Cr-doping on outputs of modules, two paired p-n modules consisting of n-type purchased Mg2Si and p-type Cr-doped HMS with x = 0, 0.05, 0.10, and 0.20 elements were prepared. The module consisting of (Mn0.9Cr0.1)Si1.75 showed the highest output, that is, 845 mW at 873 K on the hot side. There was approximately 8% improvement compared with that of the module consisting of Cr-free elements.

We applied NiSi2 as an electrode for thermoelectric modules because NiSi2 has high electric conductivity and is expected to suppress the inter-diffusion of Si from MgSi2 and higher manganese silicide (HMS). The thermal expansion coefficient of NiSi2 is close to that of Mg2Si but differs from that of HMS. Therefore, to reduce thermal stress, we tried to insert a buffer layer consisting of HMS and NiSi2 for the interface between the HMS sintered body and the NiSi2 electrode. The NiSi2 was prepared by using spark plasma sintering (SPS) equipment. NiSi2 electrodes and gradients were formed and connected with the HMS by SPS treatment. Crack-free bonding was achieved by inserting gradients consisting of HMS and NiSi2. The inserted composite buffer layer reduced interface stress and interface resistance between HMS and NiSi2.

A new chemical oxidation method was proposed to mimic the crystalline structure change of cathode materials during charge-discharge process by chemical treatment as an efficient experimental data collection method for exploring cathode materials for lithium batteries by informatics such as machine learning. LiNi0.5Mn1.3Ti0.2O4 prepared by the solid-state reaction method was soaked in 2 ​mol/L HNO3 for 10 days, and the chemical delithiation about 53% was confirmed. Furthermore, from the information obtained by synchrotron XRD and XAFS measurements, it could be predicted that the chemical oxidation reaction was accompanied by delithiation. In HCl and H2SO4, which are different acids, the lattice parameter decreased with decreasing Li composition as in the case of HNO3. However, from the value of the metal-oxygen octahedral volume calculated from the crystal data obtained by structure refinement, it was concluded that the Li+ to H+ ion-exchange reaction rather than the oxidation reaction proceeded in HCl.

We focused on a micro diamond (MD) particle with the highest thermal conductivity among existing materials and aimed to make a MD/copper composite material by electroplating. However, copper is naturally non-wetting with MD due to its chemical incompatibility, leading to weak interfacial bonding and high thermal resistance. We improved the wettability between MD and copper functionalized by the amino group on the MD using a photocatalytic reaction. The functionalization of the diamond surface by amino groups was achieved by treating the MDs in a 3-aminopropyltrimethoxysilane-containing solution. The amino group functionalized MD was dispersed in the electroplating bath, where copper was deposited on the MD. As a result, the composite material of amino group functionalized MD assisted by photocatalyst and copper improved their interfacial affinity and exhibited the high thermal conductivity of 595 W/m K.

The magnesium compound Mg2Si and its solid solutions are expected as n-type thermoelectric (TE) material because they are non-toxic, have a large Clarke number, and are light weight. In this study, we improved TE performance by doping Ge into Sb-doped Mg2Si to cause phonon scattering and increase carrier concentration. A bulk of Sb-doped Si-Ge alloy as the raw material was fabricated using an arc-melting method. A high-purity Mg2Si was synthesized from metal Mg and Sb-doped Si-Ge alloy using spark plasma sintering equipment. For the samples with the same Sb concentration, the electrical conductivity was equivalent. On the other hand, the Seebeck coefficient was dependent on Ge concentration. Due to phonon scattering, thermal conductivity decreased by a small amount of Ge doping and κ ph dominated for thermal conduction. The minimum thermal conductivity of Mg2Si0.90Ge0.10 was 2.25 W/mK (κ ph : 2.06 W/mK, κ el : 0.19 W/mK). The dimensionless figure of merit (ZT) for the Mg2Si0.945Ge0.05Sb0.005 sample was higher than that of the others due to reducing thermal conductivity and increasing carrier concentration. The maximum ZT was 0.47 at 713 K.

High-quality single-phase epitaxial LiCoO2 thin films are synthesized on 0.5 wt % Nb-doped SrTiO3(001) substrates by nanoscale alternate deposition of Li2CO3 and CoO as Li and Co sources, respectively, using a combinatorial pulsed laser deposition (PLD) technique. The formation of LiCoO2 thin films from these two sources results from the sintering reaction between Li2CO3 and CoO, which is commonly used in a bulk ceramics process, but simultaneously takes place on the substrate during the deposition at a temperature of 550 °C. Electrochemical characterization reveals that the charge/discharge property of LiCoO2 thin films as a cathode is severely sensitive to the nominal Li:Co composition ratio. The best-quality film shows an excellent discharge capacity comparable with the characteristic capacity of LiCoO2.

We established a Ca1-x Bi x Mn1-y Ni y O3 (0 ≤ x, y ≤ 0.1) powder library using a combinatorial system based on the electrostatic spray deposition method. Single phase perovskite-type structures were identified in all of the powders. To measure electrical conductivity, the powder library was subjected to high-pressure (200 MPa) and heat-treated at 950°C for 1 hour in an oxygen atmosphere. As a representative example, the electrical conductivity of 5%-Bi-substituted CaMnO3-δ showed a higher value (63 S·cm-1) than an unsubstituted powder (13 S·cm-1). The improved electrical conductivity, on the other hand, was still very far from the ideal result (167 S·cm-1).

The pulsed jet technique was applied to measure the electrical resistance response of a Zn-terminated ZnO(0001) substrate to trace ethanol in the air to simulate the realistic working surface of a semiconductor gas sensor in a vacuum. The resistance response to the trace ethanol under the static atmospheric pressure air was well reproduced by the periodic pulsed jet technique with the optimal irradiation conditions, in which the pressure in the vicinity of the surface transiently reached 2 kPa. The behavior of the resistance upon the pulsed jet irradiation was discussed in terms of the ionosorption of oxygen. Because the background pressure was kept low enough during the pulsed jet irradiation, the reaction products during the ethanol sensing, such as acetaldehyde, has been successfully detected at the elevated temperature above 400 K by temperature programmed desorption-mass spectrometry (TPD-MS).

Molybdenum-doped zirconium tungstate (ZrW2&minus, xMoxO8) has been widely studied because of its large isotropic coefficient of negative thermal expansion (NTE). However, low density and poor sinterability limit its production and application. In this study, relative density greater than 90% single-phase ZrW2&minus, xMoxO8 (0.0 &le, x &le, 1.0) sintered bodies were fabricated by spark plasma sintering (500&ndash, 600 &deg, C for 10 min) using ZrW2&minus, xMoxO7(OH)2&middot, 2H2O precursor powders as the starting material. High-temperature X-ray diffraction and thermomechanical analysis were used to investigate the change in the order&ndash, disorder phase transition temperature of the sintered materials, it gradually dropped from 170 &deg, C at x = 0.0 to 78 &deg, C at x = 0.5, and then to below room temperature at x &ge, 0.7. In addition, all sintered bodies exhibited NTE behavior. The NTE coefficient was controllable by changing the x value as follows: from &minus, 7.85 &times, 10&minus, 6 &deg, C&minus, 1 (x = 0) to &minus, 9.01 &times, 1 (x = 0.6) and from &minus, 3.22 &times, 2.50 &times, 1 (x = 1.0) before and after the phase transition, respectively. Rietveld structure refinement results indicate that the change in the NTE coefficient can be straightforwardly traced to the thermodynamic instability of the terminal oxygen atoms, which only have one coordination.

High-performance hydrogen gas sensors are needed to ensure safe use of hydrogen gas as a clean energy resource. Pt catalyst-loaded tungsten oxide (Pt/WO 3 ), which shows gasochromism, is an excellent candidate for optical hydrogen gas sensor applications. Pt/WO 3 turns blue in a hydrogen gas atmosphere and its electrical conductivity also changes at the same time. This study investigated the influence of partial pressures of hydrogen and oxygen gases on the gasochromism of Pt/WO 3 . Using elementary gasochromic reactions as a basis, we estimated the concentration of hydrogen injected into a WO 3 lattice from the equilibrium of elementary reaction velocities. The estimation suggested that the inverse of the hydrogen concentration in WO 3 was inversely proportional to the partial pressure of hydrogen and was proportional to that of oxygen. Additionally, the estimation agreed well with the results of Pt/WO 3 gasochromic properties. Therefore, we were able to confirm the dependence of gasochromism on the partial pressures of hydrogen and oxygen gases, and substantiate that Pt/WO 3 is capable of detecting hydrogen gas concentrations in various atmosphere conditions where oxygen gas partial pressures change.

Highly crystallized fine powder of strontium titanate (SrTiO3) was obtained at room temperature simply by leaving a vial containing the powder mixture of Sr(OH)2·8H2O and hydrous titania gel (TiO2·nH2O) for 10 d. Solvent and additive(s) used in the conventional low-temperature process were not used. The crystallinity judged from the FWHM of X-ray diffraction peak was comparable to that obtained by a solid-state reaction. To cause the reaction at room temperature, the titania gel had to contain a considerable amount of H2O (n > 0.97). The reaction is considered to be neutralization of titanic acid [H4TiO4 or Ti(OH)4] and strontium hydroxide (base). Using similar process, highly crystallized BaTiO3 powder was also obtained at 60°C. In comparison with the formation temperature of BaTiO3, tolerance factor in the perovskite structure was important for the room-temperature synthesis of SrTiO3. SrTiO3 was hardly obtained at room temperature by the addition of saturated strontium hydroxide solution to the hydrous TiO2 gel (n = 1.29). Therefore, the reaction seems to proceed in the hydrous titania gel. This process is characterized by three important points; “no solvent”, “no additional reagents”, and above all, “no heating”.

Magnesium silicide (Mg 2 Si) has recently attracted much interest as an n -type thermoelectric (TE) material for converting waste heat into electric power. The objective of this work was to reveal a mechanism to increase the thermoelectric properties of Mg 2 Si by Sb-doping and Ge-doping. Generally, Mg 2 Si is synthesized by all-molten method. However, this synthesis method has some problems, for example, mass defects of Mg for Mg 2 Si composition caused because the melting point of Mg 2 Si is very close to the boiling point of Mg. In this study, we tried to synthesize high purity Mg 2 Si from Mg and Si alloyed with a dopant (Sb, Ge) by spark plasma sintering (SPS). The Ge-doped samples had a higher ZT value than the ZT value of the Sb-doped sample of the same concentration without Ge because the thermal conductivity of the former was lower. The maximum ZT value of Sb0.23 at%-doped Mg 2 (Si 0.995 Ge 0.05 ) was 0.74 at 756 K.

Some perovskite oxides were prepared by the novel low-temperature synthesis using a powder mixture including hydroxides and transition oxide gels. Particularly, it was found that BaZrO3 and BaHfO3 ...

Proton diffusion in Y- and Zn-doped BaZrO3 has been studied by performing molecular dynamics (MD) simulations, where the forces acting on atoms have been computed by the density functional theory (DFT). Special attention has been paid for the dopant effect on the proton conduction. The atomic configuration of 338 atoms obtained by the simulations has been verified by infrared absorption spectroscopy and neutron and synchrotron X-ray total scattering techniques. It is found from the DFT-based MD simulation that protons tend to get localized around Zn but not Y in significant amounts even at elevated temperature. Such a trapping is also indicated by change in the infrared absorption spectra by temperature, and the atomic configuration optimized by the DFT is consistent with that refined by the reverse Monte Carlo simulation using the Bragg reflections and structure factors. From DFT calculations, it can be concluded that the differences in the effective charges between Zr and the dopants explain the reason ...

Perovskite-type AxCa1-xByMn1-yO3-δ(A; La, Bi, Y, Sr) (B; Ni, Ti, V) thin films were prepared by the conventional electrostatic spray deposition (ESD) method in order to study which kind of substitution element show better thermoelectric property than AxCa1-xByMn1-yO3-δ. Electrical conductivity of the single-doped compound was increased when the substituted element was higher valence than Ca or Mn ion. PF value also showed similar tendency. Thermoelectric property of all compounds obtained the ESD method were consistent with the report of the solid-state reaction. Also, co-doped Bi0.02Ca0.98Mn0.98V0.02O3-δ and Bi0.02Ca0.98Mn0.98Ni0.02O3-δ showed relatively higher conductivity and PF value.