Effects of W~(6+) occupying Sc~(3+) on the structure,vibration, and thermal expansion properties of scandium tungstate |
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Institution: | 1.School of Materials Science & Engineering, Zhengzhou University of Aeronautics, Zhengzhou 450046, China;2.Key Laboratory of Materials Physics of Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450052, China |
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Abstract: | We experimentally investigate effects of W6+ occupying the sites of Sc3+ in the unit cell of Sc2W3O12 (Sc8W12O48) on the structure, vibration and thermal expansion. The composition and structure of the doped sample (Sc6W2)W12O48±δ (with two W6+ occupying two sites of Sc3+ in the unit cell of Sc8W12O48) are analyzed and identified by combining the x-ray photoelectron spectroscopy and the synchronous x-ray diffraction with first-principles calculations based on density functional theory. Results show that the crystal with even W6+ occupying even Sc3+ in the unit cell is stable and maintains the orthorhombic structure at room temperature. The structure of the doped sample is similar to that of Sc2W3O12, and with even W occupying even positions of Sc in the unit cell and constituting the WO6 octahedra. Raman analyses show that the doped sample possesses stronger W-O bonds and wider Raman linewidths than those of Sc2W3O12. The sample doped with W also exhibits intrinsic negative thermal expansion in the measured range of 150 K-650 K. |
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Keywords: | structure negative thermal expansion Raman spectroscopy |
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