Laser based traveling-solvent floating-zone (TSFZ) furnace for synthesis of large high purity single crystals. Ideal for synthesis of transition metal oxides and intermetallic compounds. The TSFZ method is particulary useful for the growth of non-congruent melting materials.
Laser floating zone furnace
The furnace is equipped with five 200 W lasers capable of heating materials to about 2800 °C at full power. The laser beams have a flat top profile with 5 mm x 8 mm vertical x horizontal width. A few non standard features were included in the design, such as an increased maximum crystal growth length, and a pyrometer that can scan the temperature profile over several centimeters in vertical direction, i.e., across the liquid zone.
Feed rod preparation
Preparation of a dense and straight feed rod with uniform diameter is a crucial step for succesful TSFZ growth. This is our way of filling powder into a silicone rubber tube. The supporting steel pipe can be evacuated to inflate the rubber tube, although this is usually not needed. Different dimensions are available.
The powder in the rubber tube is then hydrostatically compacted at about 2700 bar in a cold isostatic press. The maximum pressure of the device is about 4000 bar, but wear and tear increases. The vessel has an interior diameter of 3 inches, and its interior length of 16 inches is a bit larger than the standard, providing sufficient room to accommodate extra long feed rods if needed.
This top loading 1400 °C furnace can accomodate several feed rods with a maximum length of 300 mm. Feed rods are suspended using a platinum wire to avoid contamination through contact with crucible material.
In recent years several groups have published great articles about the TSFZ method:
- Active Crystal Growth Techniques for Quantum Materials, J. L. Schmehr and S. D. Wilson, Annu. Rev. Mater. Res. 47, 153 (2017).
- Floating Zone Growth of Oxides and Metallic Alloys, H. A. Dabkowska and A. B. Dabkowski, Handbook of Crystal Growth (2nd Edition), 281 (2015).
- Growth and Characterization of Bulk Superconductor Material, D. Chen, C. Lin, A. Maljuk, and F. Zhou, Springer Series in Materials Science, 243 (2016).
- High-pressure laser floating zone furnace, J. L. Schmehr, M. Aling, E. Zoghlin, and S. D. Wilson, Rev. Sci. Instrum. 90, 043906 (2019).
- T. Ito, T. Ushiyama, Y. Yanagisawa, Y. Tomioka, I. Shindo, A. Yanase, Journal of Crystal Growth 363, 264 (2013).