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.

本誌第71巻10号に掲載の刈屋翔太氏，永田晃貴氏，梅田純子氏，Biao Chen氏，Jianghua Shen氏，Shufeng Li氏，近藤勝義氏の研究論文「Sc添加Ti-Zr系焼結合金の強化機構」につきまして，著者より訂正の申し出がありました．訂正箇所は下記の通りです．

488ページ右下

正

また，Sc₂O₃分散粒子による強化量は式(4)により求められる^33-35)．

 (4)

誤

また，ひずみ密度ρ_GNDは式(4)より求められる^33,34)．

 (4)

本誌第71巻10号に掲載の刈屋翔太氏，田中貴之氏，梅田純子氏，Yafeng Yang氏，Shaofu Li氏，Anak Khantachawana氏，Abdollah Bahador氏，近藤勝義氏の研究論文「α+β 2相Ti-Fe 焼結圧延材の組織形成機構」につきまして，著者より訂正の申し出がありました．訂正箇所は下記の通りです．

510ページAbstract 2行目

正

With an increase in the Fe content, the volumetric fraction of the β-Ti phase, which contains high Fe solutes, drastically increased.

誤

With an increase in the Fe content, the volumetric fraction of the β-Ti phase, contains high Fe solutes, drastically increased.

本誌第71巻12号に掲載の刈屋翔太氏，Issariyapat Ammarueda氏，Abdollah Bahador氏，Ma Qian氏，梅田純子氏，近藤勝義氏の研究論文「レーザ粉末床溶融法により作製した過飽和鉄固溶αチタン合金の結晶組織と強化機構」につきまして，著者より訂正の申し出がありました．訂正箇所は下記の通りです．

690ページ左側，下から8行目

正

まず，結晶粒微細化による強化量をHall-Petchの経験則に基づいて定量的に評価した．各試料のYS，ΔYS，結晶粒微細化による強化量とその差分をTable 2にまとめた．なお，Hall-Petch係数として，既往研究¹⁹⁾に報告されている値から計算した147.8 MPa μm^1/2を用いた．

誤

まず，結晶粒微細化による強化量をHall-Petchの経験則に基づいて定量的に評価した．なお，Hall-Petch係数として，既往研究¹⁹⁾に報告されている値から計算した147.8 MPa μm^1/2を用いた．