Gold-Colored Bizen Stoneware

[Magnolia Mud Research]

This article (detailed below) appeared in an recent ACS weekly newsletter: 

I'm recommending the article because the article
1.  is about ceramic art (and craft);
2.  is about chemistry (which is an important of the art); 
3.  provides insights of how atoms of Fe and Al can substitute for other atoms in crystalline and glassy phases in a ceramic matrix. 

the article details and links are below.  The image is figure 1 from the article.  read and enjoy.

LT

 

Alchemy in the Art of Traditional Japanese Ceramics: Microstructure and Formation Mechanism of Gold-Colored Bizen Stoneware
Yoshihiro Kusano, Minoru Fukuhara, Taichi Fujino, Tatsuo Fujii, Jun Takada, and Mikio Takano
Crystal Growth & Design 2018 18 (7), 4017-4021 
DOI: 10.1021/acs.cgd.8b00368 

You can read it online here:  
https://pubs.acs.org/doi/10.1021/acs.cgd.8b00368 

ACS Editors' Choice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

Synopsis:
The lustrous golden color of traditional Japanese Bizen stoneware was attributed to the yellowish color of a 100 nm thick Al-substituted hematite layer and the light reflected from the glassy phase. The color is reproducible in the laboratory through sequential heat treatments of Bizen clay pellets under oxidizing and reducing atmospheres with potassium supplied as a melting point depressant.

Abstract:

The microstructure and formation process of the golden color on traditional Japanese Bizen stoneware was investigated through model experiments. The current compositional and structural research of pottery fragments has revealed that the golden color comes from Fe oxide consisting of approximately 100 nm thick agglomerates of Al-substituted hematite (a-(Fe1–xAlx)2O3, x ˜ 0.05). The color is reproducible in the laboratory by sequential heat treatments of Bizen clay pellets under oxidizing and reducing atmospheres with an amount of potassium supplied as a melting point depressant. Lustrous colors such as silver and gold in Bizen stoneware have generally been attributed to the optical interference in superficial carbon films produced by burning wood fuel. Here, we show that the golden color is caused by the formation of Al-substituted hematite, not by the formation of carbon.