Optical, electrical, and X-ray-structural studies on Verneuil-grown SrTiO3 single crystal: Annealing study

✍ Scribed by S. Mochizuki; F. Fujishiro; K. Shibata; A. Ogi; T. Konya; K. Inaba

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 337 KB
• Volume: 401-402
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2007.08.205

✦ Synopsis

In order to clarify crystal defect effects on the physical phenomena observed for a SrTiO 3 single crystal grown by Verneuil method, the optical density and photoluminescence spectra, complex impedance spectra, and crystal structure were fully studied for the as-grown crystal boule. The as-grown crystal boule consists of a shell (which is colorless transparent and electrically good insulator) and a core (which is dark blue and has a high electrical conductivity (410 -3 O -1 cm -1 ), and a colossal static dielectric constant (410 6 ) at room temperature). The as-grown single crystal was then annealed at 973 K in an Ar-H 2 gas stream. With the progressing of annealing, the asgrown single crystal becomes colorless-transparent insulator and the static dielectric constant decreases down to approximately 300 at room temperature. The X-ray crystallographic studies indicate that the crystallinity is almost independent of the annealing, while the dielectric property is considerably affected by the annealing. A model on the basis of a (Ti 3+ -oxygen vacancy) complex defect is proposed for explaining the observed properties of SrTiO 3 .