Studying and Utilizing Traditional Technologies: Microstructure and Formation Mechanism of ε-Fe₂O₃ on Traditional Japanese Bizen Stoneware

Abstract

Traditional Japanese Bizen stoneware is produced by firing a specific type of green clay in a wood-fired kiln at approximately 1200 °C. During this process, single crystalline branched dendrite-like particles of Al-substituted ε-Fe2O3 (ε-Fe1.7Al0.3O3) with widths and lengths of approximately 15 and 30 μm, respectively, are formed on the surface of the ceramic. Composite particles consisting of ε-Fe2O3 epitaxially connected to spinel structure compounds [comprising the Fe-substituted spinel (Mg,Fe)­(Al,Fe)2O4 and γ-Fe2O3)] with lengths of approximately 3 μm are also generated. The present work clarified the crystallographic relationship between ε-Fe2O3 and the spinel structure compounds. In addition, brown-colored samples similar to Bizen pottery and with surface Al-substituted ε-Fe2O3 particles were prepared by heating clay with K2CO3 under a 10 vol % CO gas and 90 vol % Ar gas mixture using an electric furnace instead of a firewood kiln. Hence, a traditional method was adapted to achieve the industrial production of ε-Fe2O3 crystals.

Spinodal Decomposition in the Mg–Al–Fe–O System

“…These diagrams and the ED patterns in Figure a indicate that the crystallographic relationship between the ε-Fe 2 O 3 and the spinel structure compound was a ε // [112̅] s , b ε // [1̅10] s , and c ε // [111] s , where the indices ε and s indicate the ε-Fe 2 O 3 and spinel structure compound, respectively. This crystallographic relationship is consistent with that previously determined in the case of particles formed in Bizen stoneware …”

“…Our group has studied the application of traditional techniques, such as the process by which colors are applied to Japanese ceramics, with the aim of transitioning these same methods to the production of industrial materials. , In prior examinations of Bizen stoneware having a silvery luster, we found composite particles consisting of ε-Fe 2 O 3 and a spinel structure compound in the Mg–Al–Fe–O system. Iron­(III) oxide, typically referred to as Fe 2 O 3 , has four polymorphs: α-, β-, γ-, and ε-Fe 2 O 3 .…”

Uncovering the mystery of Al(III) doping of ε‐Fe2O3 in the ancient high‐iron black‐brown glaze

“…Moreover, according to the latest study, Al-substituted ε-Fe 2 O 3 was also found on a Japanese Bizen stoneware replica, which is widely believed to be profoundly influenced by Chinese high-fired black-glazed tea cups. 29…”

A magnetic field-switchable millimeter wave switch for 81, 94, and 140 GHz based on metal substituted ε-iron oxide

“…Epsilon iron oxide (ε-Fe 2 O 3 ) nanomagnets are receiving attention due to their large magnetic coercivity and high-frequency millimeter wave absorption at 182 GHz. 17–37 Additionally, metal-substituted ε-Fe 2 O 3 (ε- M x Fe 2− x O 3 ) exhibits zero-field ferromagnetic resonance over a wide frequency range of 35–222 GHz. 38–50 ε- M x Fe 2− x O 3 has entered the market as a millimeter wave absorber due to these useful properties.…”