Exploration of the Electronic Structure of Monoclinic α-Eu2(MoO4)3: DFT-Based Study and X-ray Photoelectron Spectroscopy

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• 作者：Ali H. Reshak ; Z. A. Alahmed ; J. Bila ; Victor V. Atuchin ; Bair G. Bazarov ; Olga D. Chimitova ; Maxim S. Molokeev ; Igor P. Prosvirin ; Alexander P. Yelisseyev
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 19, 2016
• 年：2016
• 卷：120
• 期：19
• 页码：10559-10568
• 全文大小：710K
• 年卷期：0
• ISSN：1932-7455

文摘

The powder α-Eu₂(MoO₄)₃ sample was prepared by the solid-state reaction method. The phase purity of the final powder product was verified by X-ray diffraction analysis. The constituent element core levels and valence band are measured by X-ray photoelectron spectroscopy as a function of Ar⁺ ion (2.5 keV, 7–8 μA/cm²) bombardment time. The formation of Mo⁵⁺ and Mo⁴⁺ states at high bombardment times was detected. The Eu–O and Mo–O bonding was considered in comparison with other Eu³⁺- and Mo⁶⁺-containing oxides using binding energy difference parameters. The transparency range obtained for the pure α-Eu₂(MoO₄)₃ tablet is λ = 0.41–0.97 μm, as estimated at the transmission level of 5%. The short-wavelength cut edge in α-Eu₂(MoO₄)₃ is governed by the direct allowed optical transitions within the band gap of E_g = 3.74 eV (300 K). The band structure of α-Eu₂(MoO₄)₃ was calculated by ab initio methods and strongly different results were obtained for the spin up/down configurations. The Eu-4f states are located around 2.2 eV and −4.0 eV for spin up (↑) and the structures situated at around 6.5 and 5.5 eV for spin down (↓) configuration. The calculated spin magnetic moments are in excellent relation to the Slater-Pauling rule and within the Eu sphere the magnetic moment of 4f electrons is ∼5.99 μB.