Magnetic Properties and Electronic Structure of Manganese-Based Blue Pigments: A High-Frequency and -Field EPR Study

详细信息    查看全文

• 作者：J. Krzystek ; Joshua Telser ; Jun Li ; M. A. Subramanian
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：September 21, 2015
• 年：2015
• 卷：54
• 期：18
• 页码：9040-9045
• 全文大小：367K
• ISSN：1520-510X

文摘

A variety of new oxide-based materials based on hexagonal phase of YInO₃ have been recently described. In some of these materials, the In(III) ions are substituted by Mn(III), which finds itself in a trigonal-bipyramidal (TBP) coordination environment. While YInO₃ is colorless and YMnO₃ is black, mixed systems YIn_1鈥?i>xMn_xO₃ (0.02 < x < 0.25) display intense blue color and have been proposed as novel blue pigments. Since the Mn(III) ion is paramagnetic, its presence imparts distinct magnetic properties to the whole class of materials. These properties were investigated by electron paramagnetic resonance (EPR) in its high-frequency and -field version (HFEPR), a technique ideally suited for transition metal ions such as Mn(III) that, in contrast to, for example, Mn(II), are difficult to study by EPR at (conventional) low frequency and field. YIn_1鈥?i>xMn_xO₃ with 0.02 < x < 0.2 exhibited high-quality HFEPR spectra up to room temperature that could be interpreted as arising from isolated S = 2 paramagnets. A simple ligand-field model, based on the structure and optical spectra, explains the spin Hamiltonian parameters provided by HFEPR, which were D = +3.0 cm^鈥?, E = 0; g_{鈯?/sub> = 1.99, g鈭?/sub> = 2.0. This study demonstrates the general applicability of a combined spectroscopic and classical theoretical approach to understanding the electronic structure of novel materials containing paramagnetic dopants. Moreover, HFEPR complements optical and other experimental methods as being a sensitive probe of dopant level.}