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Direct measurement reveals charge distribution at nanoscale ferroelectric interfaces

Multilayer ceramic capacitors (MLCCs), which utilize ferroelectric ceramics, are widely used as electronic components in various devices such as smartphones, personal computers, televisions, and automotive systems.

With the advancement of mobile devices, home appliances, and IoT technologies, there is an increasing demand for MLCCs to become more compact, offer higher capacitance, and exhibit greater reliability. MLCCs are structured with alternating layers of ferroelectric material and internal electrodes. Within the ferroelectric layers, there are domains with differing polarization directions, as well as domain interfaces on the nanometer scale.

These domain interfaces are believed to contain charges resulting from changes in polarization, along with compensating charges of opposite polarity that accumulate to maintain electrical neutrality.

The state of these charges is considered to influence phenomena such as domain reconfiguration under applied voltage and the generation of leakage current, thereby critically affecting the performance and reliability of MLCCs. However, directly measuring the charge state at ferroelectric domain interfaces at the nanometer scale has remained extremely difficult.

A research team led by Dr. Takehito Seki, Lecturer at the Institute of Engineering Innovation, School of Engineering, the University of Tokyo, achieved direct measurement of nanometer-scale charge distributions formed at ferroelectric domain interfaces. The results are published in .

This was accomplished through the combination of localized charge observation and the observation of atomic displacements on the picometer (one-trillionth of a meter) scale using state-of-the-art electron microscopy. This research marks a significant step toward elucidating the mechanisms of domain interface movement and electrical conductivity in ferroelectric materials.

It is expected to lead to a deeper understanding of the intrinsic properties of ferroelectric devices and contribute to future advancements in their performance.

The results of this development were achieved as part of the research project "SHIBATA Ultra-atomic Resolution Electron Microscopy." In this project, JST aims to develop a new measurement technique that can be called an ultra atomic resolution electron microscopy that goes beyond conventional atomic resolution electron microscopy, allowing simultaneous observation of atomic-scale structures and electromagnetic field distributions in the temperature range from extremely low to high temperatures.

This will enable direct observation of the origins of materials and biological functions.