Thermoelectric materials, which can generate electricity from waste heat or be used as solid-state Peltier coolers, could play an important role in a global sustainable energy solution. Such a development is contingent on identifying materials with higher thermoelectric efficiency than available at present, which is a challenge owing to the conflicting combination of material traits that are required. Nevertheless, because of modern synthesis and characterization techniques, particularly for nanoscale materials, a new era of complex thermoelectric materials is approaching. We review recent advances in the field, highlighting the strategies used to improve the thermopower and reduce the thermal conductivity.

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Complex thermoelectric materials.

TiO2 photocatalysis and related surface phenomena

Spurred by recent progress in materials chemistry and drug delivery, stimuli-responsive devices that deliver a drug in spatial-, temporal- and dosage-controlled fashions have become possible. Implementation of such devices requires the use of biocompatible materials that are susceptible to a specific physical incitement or that, in response to a specific stimulus, undergo a protonation, a hydrolytic cleavage or a (supra)molecular conformational change. In this Review, we discuss recent advances in the design of nanoscale stimuli-responsive systems that are able to control drug biodistribution in response to specific stimuli, either exogenous (variations in temperature, magnetic field, ultrasound intensity, light or electric pulses) or endogenous (changes in pH, enzyme concentration or redox gradients).

Stimuli-responsive nanocarriers for drug delivery

Titanium dioxide, TiO2, is an important photocatalytic material that exists as two main polymorphs, anatase and rutile. The presence of either or both of these phases impacts on the photocatalytic performance of the material. The present work reviews the anatase to rutile phase transformation. The synthesis and properties of anatase and rutile are examined, followed by a discussion of the thermodynamics of the phase transformation and the factors affecting its observation. A comprehensive analysis of the reported effects of dopants on the anatase to rutile phase transformation and the mechanisms by which these effects are brought about is presented in this review, yielding a plot of the cationic radius versus the valence characterised by a distinct boundary between inhibitors and promoters of the phase transformation. Further, the likely effects of dopant elements, including those for which experimental data are unavailable, on the phase transformation are deduced and presented on the basis of this analysis.

https://link.springer.com/content/pdf/10.1007%2Fs10853-010-5113-0.pdf

Review of the anatase to rutile phase transformation

Herein we cover the key concepts in the field of thermoelectric materials research, present the current understanding, and show the latest developments. Current research is aimed at increasing the thermoelectric figure of merit (ZT) by maximizing the power factor and/or minimizing the thermal conductivity. Attempts at maximizing the power factor include the development of new materials, optimization of existing materials by doping, and the exploration of nanoscale materials. The minimization of the thermal conductivity can come through solid-solution alloying, use of materials with intrinsically low thermal conductivity, and nanostructuring. Herein we describe the most promising bulk materials with emphasis on results from the last decade. Single-phase bulk materials are discussed in terms of chemistry, crystal structure, physical properties, and optimization of thermoelectric performance. The new opportunities for enhanced performance bulk nanostructured composite materials are examined and a look into the not so distant future is attempted.

New and Old Concepts in Thermoelectric Materials

Decomposition Pressure of Co 3 O 4 Determined from Electrical Conductivity Measurements

We studied surface modification of ceramic BaTiO(3) green sheets including polyvinylbutyral (PVB) as an organic binder and successfully fabricated a patterned self-assembled monolayer (SAM) which has a region of amino groups and a region of silanol groups on the green sheet. The patterned SAM was then immersed in water containing Ni particles that show negative zeta potential in water. Ni particles were attracted to the amino groups of the patterned SAM that show positive zeta potential by attractive electrostatic interaction. Consequently, a micropattern of Ni particles was achieved using a SAM at room temperature in water. This process can be used to fabricate a thin uniform internal Ni electrode for miniaturized high-performance multilayer ceramic capacitors (MLCC).

Micropatterning of Ni particles on a BaTiO3 green sheet using a self-assembled monolayer.

The characteristics of Positive Temperature Coefficient of Resistivity (PTCR) thermistors depend strongly on the atmosphere, especially oxygen, during the fabrication process. The PTCR jump decreases when the sample is heated in a reducing atmosphere, while it increases when the sample is heated in air. The behavior of oxygen which is important to improve the PTCR jump has been examined by a tracer (18O) method. The depth profile of the tracer has been determined by means of Secondary ion mass spectrometry (SIMS). The rate of penetration of oxygen into the grain boundary is very rapid and the PTCR jump depends on the amount of the oxygen penetrated into such a region.

https://iopscience.iop.org/article/10.1143/JJAP.30.1252/pdf

The Enhanced Penetration of Oxygen along the Grain Boundary in Semiconducting Barium Titanate

Crystal growth of lepidocrocite and magnetite under Langmuir monolayers

Bien que le mecanisme de l'effet de l'humidite ne soit pas encore clarifie, la jonction p-n Li-CuO/ZnO presente des proprietes prometteuses pour la fabrication de dispositifs de detection de l'humidite

https://iopscience.iop.org/article/10.1143/JJAP.22.1933/pdf

Kunihito Koumoto

Papers

Decomposition Pressure of Co 3 O 4 Determined from Electrical Conductivity Measurements

Micropatterning of Ni particles on a BaTiO3 green sheet using a self-assembled monolayer.

The Enhanced Penetration of Oxygen along the Grain Boundary in Semiconducting Barium Titanate

Crystal growth of lepidocrocite and magnetite under Langmuir monolayers

Effect of Relative Humidity on Current-Voltage Characteristics of Li-Doped CuO/ZnO Junction