CoO-MgO-Al₂O₃-Cr₂O₃-Fe₂O₃系スピネル固溶体の生成とその色

抄録

This study was concerned with the formation and color development of the spinel solid solution in CoO-MgO-Al₂O₃-Cr₂O₃-Fe₂O₃ system, and its application to colored glazes.
Specimens were prepared by calcining the oxide and hydroxide mixtures at 1400°C for 1hr. The formation of spinel solid solution was examined by X-ray diffraction, the color was discussed by measuring the spectral reflectance and the stability of the spinel in glazes was tested. The results were summarized as follows.
1) Formation of a continuous solid solution was confirmed by X-ray analysis.
2) As the amount of Cr³⁺ increased in MgO-Al₂O₃-Cr₂O₃ system, the color changed from white through pale pinkish beige and grayish yellow to grayish leaf, and the absorption of Cr³⁺ shifted towards red region.
3) An increase of Fe³⁺ in MgO-Al₂O₃Fe₂O₃ system, caused the color to change from white through dull orange yellow to grayish brown.
4) As the amount of Fe³⁺ increased in MgO-Cr₂O₃Fe₂O₃ system, the color changed from grayish leaf through dark grayish red to grayish brown, and when Cr³⁺ and Fe³⁺ coexisted, an additional absorption was observed within a range of 600-700mμ
5) Colors obtained in MgO-Al₂O₃-Cr₂O₃-Fe₂O₃ system, ranged from yellowish brown through brown to dark grayish red.
6) Brilliant hue, so-called cobalt-blue, developed in CoO-MgO-Al₂O₃ system. An increase of Cr³⁺ in CoO-MgO-Al₂O₃-Cr₂O₃ system, yielded the colors ranging greenish blue to blue green so-called peacock.
7) In CoO-MgO-Al₂O₃-Cr₂O₃-Fe₂O₃ system, colors ranging from grayish olive green to dark gray developed, as the amount of Fe³⁺ increased.
8) An increase of Fe³⁺ in CoO-MgO-Cr₂O₃-Fe₂O₃ system, yielded the colors ranging from turquoise through reddish gray to dark gray.
9) Colors ranging from grayish olive to dark purplish gray developed in CoO-MgO-Al₂O₃-Cr₂O₃-Fe₂O₃ system.
10) According to the result of the colored glaze test, these MgO-containing spinels with the composition in Cr³⁺ rich region were stable as a glaze stain.