High-Figure-of-Merit Thermoelectric La-Doped A-Site-Deficient SrTiO3 Ceramics

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• 作者：Zhilun Lu ; Huairuo Zhang ; Wen Lei ; Derek C. Sinclair ; Ian M. Reaney
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：February 9, 2016
• 年：2016
• 卷：28
• 期：3
• 页码：925-935
• 全文大小：761K
• ISSN：1520-5002

文摘

The structure and thermoelectric (TE) properties of La-doped, A-site-deficient SrTiO₃ (Sr_1–3x/2La_xTiO₃) ceramics sintered in air and N₂/5% H₂ have been investigated. Air-sintered ceramics with 0.10 ≤ x < 0.30 appear cubic by X-ray diffraction (XRD) but exhibit superstructure consistent with a tetragonal cell (a⁰a⁰c^–), according to electron diffraction (ED) studies. 0.30 ≤ x < 0.50 have additional short-range A-site vacancy (V_A) ordering, and x ≥ 0.50 are orthorhombic with an a^–a^–c⁺ tilt system and long-range V_A ordering. 0.10 ≤ x ≤ 0.50 reduced in N₂/5% H₂ are oxygen-deficient and appear cubic in XRD patterns but exhibit superstructure compliant with an a⁰a⁰c^– tilt system by ED. For x = 0.50, additional short-range V_A order is observed, and x > 0.50 are orthorhombic with an a^–a^–c⁺ tilt system and long-range V_A ordering. x = 0.15 sintered in N₂/5% H₂ shows the largest dimensionless TE figure-of-merit ZT = 0.41 at 973 K reported for n-type SrTiO₃-based ceramics, suggesting that the accommodation of La through formation of (V_Sr) coupled with reduction in N₂/5% H₂ represents a new protocol for the development of oxide-based thermoelectrics.