The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30

Dongting Jiang, Dursun Ekren, Feridoon Azough, Sarah J. Day, Kan Chen, Amit Mahajan, Demie M. Kepaptsoglou, Quentin M. Ramasse, Michael J. Reece, Robert Freer

Research output: Contribution to journalArticlepeer-review


Tungsten bronze structured materials have attracted attention as possible thermoelectrics because of their complex crystal structure. In this work, a new thermoelectric ceramic with tetragonal tungsten bronze (TB) structure, Ba6Ti2Nb8O30 (BTN) was prepared by the conventional mixed oxide (MO) route with some samples processed by Spark Plasma Sintering (SPS). Additions of MnO enabled fabrication of high density BTN ceramics at the low sintering temperature of 1580 K in air and by SPS. All samples were annealed in a reducing atmosphere after sintering. X-ray diffraction showed that Ba6Ti2Nb8O30 crystallises with tetragonal symmetry (P4bm space group). HAADF-EELS analysis confirmed the proposed crystal structure and provided exact elemental distributions in the lattice, showing higher concentrations of Ti in the 2b lattice sites compared to the 8d lattice sites. XPS showed the presence of two spin-orbit double peaks at 207.7eV in the reduced BTN samples, confirming the presence of Nb4+ ions. By the use of a sintering aid and optimisation of the processing parameters the ceramics achieved a high power factor of 280 μW/m∙K2 at 873 K. The BTN ceramics showed phonon glass type thermal conduction behaviour with low thermal conductivity of 1.7 to 1.65 W/m.K at 300 to 873 K. A thermoelectric figure of merit (ZT) of 0.14 was achieved at 873 K. This ZT value is comparable with results for many TB thermoelectrics. However, BTN has the advantage of much easier processing.
Original languageEnglish
JournalJournal of Applied Physics
Early online date27 Sept 2019
Publication statusPublished - 2019


  • Tungsten bronze
  • Ba6Ti2Nb8O30
  • thermoelectric
  • thermal conductivity


Dive into the research topics of 'The Structure and Thermoelectric Properties of Tungsten Bronze Ba6Ti2Nb8O30'. Together they form a unique fingerprint.

Cite this