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Published on: September 28, 2019
Bulk diffusion of niobium in single-crystal titanium dioxide
Leigh R Sheppard1, Armand J Atanacio, Tadeusz Bak
1Centre for Materials Research in Energy Conversion, School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia. l.sheppard@unsw.edu.au
The Journal of Physical Chemistry. B
|June 26, 2007
Summary
This study measured niobium-93 diffusion in titanium dioxide (TiO2) rutile crystals. Niobium diffuses via the interstitialcy mechanism, crucial for controlling Nb-doped TiO2 semiconductor composition.
Area of Science:
- Materials Science
- Solid State Chemistry
- Semiconductor Physics
Background:
- Titanium dioxide (TiO2) is a vital semiconductor material.
- Controlling dopant diffusion is critical for semiconductor performance.
- Niobium (Nb) doping influences TiO2 properties.
Purpose of the Study:
- To determine the tracer diffusion coefficient of niobium-93 (93Nb) in rutile TiO2 single crystals.
- To elucidate the diffusion mechanism of Nb in TiO2.
- To provide data for controlling compositional uniformity in Nb-doped TiO2.
Main Methods:
- Tracer diffusion experiments using secondary ion mass spectrometry (SIMS).
- High-temperature diffusion anneals in air (pO2 = 21 kPa) from 1073 K to 1573 K.
- Analysis of diffusion profiles to extract diffusion coefficients.
Main Results:
- The tracer diffusion coefficient of 93Nb in rutile TiO2 was determined.
- The temperature dependence of the diffusion coefficient was established: D93(Nb) = (4.7x10^-7 +/- 0.4) exp ((-244 +/- 9 kJ mol-1)/RT) m²/s.
- Comparison with Ti self-diffusion suggests Nb diffuses via the interstitialcy mechanism.
Conclusions:
- Niobium-93 diffuses through rutile TiO2 via the interstitialcy mechanism.
- The diffusion data are essential for precise compositional control in Nb-doped TiO2 semiconductors.
- This research aids in the solid-state synthesis of advanced TiO2-based electronic materials.
