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

Traditional Japanese Bizen stoneware is produced by firing a specific type of green clay in a wood-fired kiln at approximately 1200 degrees C. During this process, single crystalline branched dendrite-like particles of AI-substituted epsilon-Fe2O3 (epsilon-Fe1.7Al0.3O3) with widths and lengths of approximately 15 and 30 mu m, respectively, are formed on the surface of the ceramic. Composite particles consisting of epsilon-Fe2O3 epitaxially connected to spinel structure compounds [comprising the Fe-substituted spinel (Mg,Fe)(Al,Fe)(2)O-4 and gamma-Fe2O3)] with lengths of approximately 3 mu m are also generated. The present work clarified the crystallographic relationship between epsilon-Fe2O3 and the spinel structure compounds. In addition, brown-colored samples similar to Bizen pottery and with surface Al-substituted epsilon-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 epsilon-Fe2O3 crystals.

Automated summary

Traditional Japanese Bizen stoneware is made by firing green clay in a wood-fired kiln to form specific particles on the ceramic surface. By using an electric furnace and adjusting the gas mixture, similar particles can also be produced industrially.