Low-Temperature Co-fired Ceramics (LTCC) have become a key technology for further miniaturization of RF circuits. Capacitors and inductors can be buried in the ceramics because LTCC can be co-fired with Cu or Ag electrode, which have low electric resistivity. LTCC, which have various dielectric constant and high Q-value, is applied to functional circuit boards and chip monolithic devices. Recently constrained sintering technology, co-firing technologies of various materials and high Q-value LTCC materials have been developed.

Constrained sintering technology improves size accuracy and flatness of substrates, and co-firing technologies contribute to further integration of microwave devices by co-firing various materials, for example high or low dielectric constant materials, printed resistors and so on. And high Q-value LTCC materials can reduce electric loss of devices. In the recent trend of using higher frequencies for wireless communication, e.g. 5G system, controlling electric loss is the biggest challenge. The higher the used frequency is, the higher the electrical loss of wireless devices is. In order to suppress stray capacitance between electric circuits, substrate material of lower dielectric constant was developed. Therefore, these technologies will integrate more passive circuit elements and contribute to further miniaturization of microwave devices and higher frequencies.

The effect of Al addition on the pressure sintering (so-called spark plasma sintering, SPS) behavior of B₄C powder by transient liquid phase sintering (TLPS) was investigated. First, an accurate sample temperature evaluation in a closed graphite die was performed using elemental standard powders. It was found that as the sintering temperature increased, the measurable die surface temperature exponentially decreased compared to the die internal temperature (i.e., sample temperature) due to thermal radiation. Next, pressure sintering treatment of the mixed powder of B₄C containing 5 vol.% Al was performed in vacuum at a constant compressive stress (50 MPa) and heating rate (2 K/s). Although densification due to Al melting was not observed at 933 K, it was found that densification began at temperatures above 1550 K, where the wettability of Al for B₄C is improved, and reached the final stage of sintering at approximately 2200 K. As a result, the densification temperature of B₄C with Al addition could be shifted to a lower temperature by approximately 250 K compared to B₄C without additives. It was suggested that the formation of Al₃BC₃ between Al and B₄C promoted the rearrangement and shape change of B₄C particles, resulting in densification at low temperatures.

In this paper, we focused on Li_1.3Nb_0.3Fe_0.4O₂ with a disordered rocksalt structure as positive-electrode materials for lithium-ion batteries, and investigated an effect of ball milling on the atomic configuration. X-ray absorption fine structure measurements and neutron and X-ray total scattering measurements were performed on an as-synthesized sample (a pristine sample) and a ball-milled sample, and it is revealed that the ball milling disrupts the atomic configuration significantly. In addition, reverse Monte Carlo modeling using the total scattering data was conducted for both the samples, and the obtained three-dimensional atomic configurations were used to visualize the space available for Li⁺ diffusion in charging and discharging processes. The results indicate that the ball milling distorts the Li⁺ diffusion path and causes fragmentation of the path, leading to a deterioration in electrode performance.