High Power Factor Nb-Doped TiO2 Thermoelectric Thick Films: Toward Atomic Scale Defect Engineering of Crystallographic Shear Structures
Year: 2023
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Donor-doped TiO 2 -based materials are promising thermoelectrics (TEs) due to their low cost and high stability at elevated temperatures. Herein, high-performance Nb-doped TiO 2 thick films are fabricated by facile and scalable screen-printing techniques. Enhanced TE performance has been achieved by forming high-density crystallographic shear (CS) structures. All films exhibit the same matrix rutile structure but contain different nano-sized defect structures. Typically, in films with low Nb content, high concentrations of oxygen-deficient {121} CS planes are formed, while in films with high Nb content, a high density of twin boundaries are found. Through the use of strongly reducing atmospheres, a novel Al-segregated {210} CS structure is formed in films with higher Nb content. By advanced aberration-corrected scanning transmission electron microscopy techniques, we reveal the nature of the {210} CS structure at the nano-scale. These CS structures contain abundant oxygen vacancies and are believed to enable energy-filtering effects, leading to simultaneous enhancement of both the electrical conductivity and Seebeck coefficients. The optimized films exhibit a maximum power factor of 4.3 × 10 –4 W m –1 K –2 at 673 K, the highest value for TiO 2 -based TE films at elevated temperatures. Our modulation strategy based on microstructure modification provides a novel route for atomic-level defect engineering which should guide the development of other TE materials.
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $5,000
Awards: University of Surrey- Equipment Account, G2158237762, G2703599441, G3305536412, G3609573722, MAnufacture of Safe and Sustainable Volatile Element functional materials - MASSIVE Materials, Thermoelectrics Network -TEMPEST (ThermoElectric Materials, Physics, Electronics & SysTems), SuperSTEM: National Research Facility for Advanced Electron Microscopy, Sir Henry Royce Institute - Manchester and NNL Equipment, G4630886971, G504327055, G5424142534, Sir Henry Royce Institute - Manchester Build, G5981071659, G601491149, Nanostructured Thermoelectric Oxides for Energy Generation: A Combined Experimental and Modelling Investigation, G6544254002, The Royce: Capitalising on the investment, G7514479249, Sir Henry Royce InsStitute - recurrent grant, G8465233624, G8640038281
OpenAlex ID: W4317435465