Optical properties and thermal stability of germanium oxide (GeO2) nanocrystals with α-quartz structure

✍ Scribed by C.V. Ramana; G. Carbajal-Franco; R.S. Vemuri; I.B. Troitskaia; S.A. Gromilov; V.V. Atuchin

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 597 KB
• Volume: 174
• Category: Article
• ISSN: 0921-5107
• DOI: 10.1016/j.mseb.2010.03.060

✦ Synopsis

Germanium dioxide (GeO 2 ) crystals were prepared by a chemical precipitation method at a relatively low-temperature (100 • C). The grown crystals were characterized by studying their microstructure, optical properties and thermal stability. The results indicate that the grown GeO 2 crystals exhibit ␣-quartz type crystal structure. The lattice parameters obtained from XRD were a = 4.987(4) Å and c = 5.652(5) Å. Electron microscopy analysis indicates a high structural quality of GeO 2 crystals grown using the present approach. Optical absorption measurements indicate a direct bandgap of 5.72 eV without any additional bands arising from localized or defect states. Thermogravimetric measurements indicate the temperature stability of the grown GeO 2 nanocrystals. Microscopic analysis coupled with energy dispersive X-ray spectroscopy of the GeO 2 crystals with ␣-quartz type crystal structure indicates their stability in chemical composition up to a temperature of 400 • C. The surface morphology of GeO 2 crystals, however, found to be changing with the increase in temperature.