Design, Synthesize, and Characterize Materials

My doctoral research was on high-temperature superconductors, which had just been discovered at the time. As my career progressed, my interests broadened to include complex metal oxides with unique properties, such as magnetic materials, thermoelectric materials, semiconductors, and dielectrics.

What I truly want to achieve is the creation of novel materials that no one has ever obtained before. To accomplish this, I use the technique of high-pressure synthesis, which involves heating materials under immense pressure—up to tens of thousands of atmospheres.

My work is a continuous cycle of looking at the periodic table, designing a material to exhibit a target function by determining the optimal elemental combinations, then synthesizing and characterizing it. The joy that comes from successfully creating a new material for the very first time is truly exceptional.

Developing Highly Sensitive Thermistors

The current project, "Material Development of Metal Oxide Thermistors by High-Entropy Effect using High-Pressure Synthesis," began when a French research colleague introduced me to high-entropy compounds.

While high-entropy materials originated in the field of alloys, they are now being applied to many ceramic systems, leading to the emergence of unprecedented, unique functionalities.

I focused specifically on the spinel-structured NTC (Negative Temperature Coefficient) thermistor. NTC thermistors are essential components in many home appliances and PCs, where they function by decreasing electrical resistance as temperature rises, enabling precise temperature sensing to prevent overheating.

Conventionally, these devices are primarily based on the material NiMn₂O₄. In our approach, we equally mixed metals like Mg, Co, and Zn into the Ni site of this compound. As a result, we successfully developed a highly sensitive thermistor that operates effectively at unusually high temperatures, ranging from 300 to 400∘C.