Structural Analysis and Luminescence Mechanism of Unique Phosphor including Structural Water

2015 Fiscal Year Final Research Report

• Project/Area Number: 26820292
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Inorganic materials/Physical properties
• Research Institution: SALESIAN POLYTECHNIC
• Principal Investigator: KUROKI Yuichiro サレジオ工業高等専門学校, その他部局等, 准教授 (90324003)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 銅添加ヒドロニウムアルナイト / 結晶水 / 水素結合 / 青紫色発光 / 局所構造解析

Outline of Final Research Achievements

Copper-doped K-alunite (KAl3(SO4)2(OH)6) which includes potassium ion at A-site, and H-alunite ((H3O)Al3(SO4)2(OH)6) were synthesized under hydrothermal conditions. The copper doped H-alunite exhibited blue luminescence at a wavelength of 420 nm. On the other hand, the K-alunite didn't show the luminescence. The hydrogen bonds introduced by the presence of H3O were observed in H-alunite. A distortion of an AlO6 octahedral cage was detected by the Rietveld analysis and Raman spectroscopy. The H-alunite showed large distortion compared to K-alunite. Under the effect of the octahedral field, the excited state of Cu+ (3d94s1) is split into three separate substates 1T2g, 1Eg and 3Eg. Generally, these energy transitions are forbidden by spin selection and Laporte's rule. Therefore, the blue luminescence is considered to be caused by partially allowed transitions related to the distorted octahedral crystal field introduced by the hydrogen bond.

Free Research Field

材料工学