Cathodoluminescence study of defects in deformed (110) and (100) surfaces of TiO₂single crystals

Abstract

In this work, the effect of different surface orientations on the defect structure of TiO 2 single crystals and the evolution of the luminescence properties under plastic deformation are investigated by cathodoluminescence (CL) microscopy. The main features of the spectra are an infrared band at 1.53 eV, and a complex band in the visible range, whose peak position depends on the electron beam energy, and is attributed to oxygen vacancy related defects. Comparison of the intensity of these bands in the spectra recorded at low electron beam voltage indicates that the Ti 3+ defects present a higher concentration at the (110) surface, whereas the (100) surface presents a more complex defect structure related to the oxygen vacancies. Competition is observed between the visible and the infrared emission centres during plastic deformation of the samples in agreement with the different diffusion mechanisms of the defects involved in the emissions.

Visible and near-infrared electroluminescence from TiO2/p+-Si heterostructured device

“…It has been reported that the visible emission from TiO 2 is related to the oxygen vacancies in the anatase phase, while the NIR emission is pertaining to the Ti 3+ ions in the rutile phase. [11][12][13]20 In our previous work, it was found that if the TiO 2 film prepared by sputtering consisted of both anatase and rutile phases, almost no EL could be detected from the TiO 2 /p + -Si heterostructured device. 21 However, in this work both the visible and NIR emissions occur in the TiO 2 /p + -Si heterostructured device with the TiO 2 film derived from the etched Ti film, which is composed of anatase and rutile phases.…”

“…10,11 However, the previous reports primarily concern the cathodoluminescence and photoluminescence of rutile TiO 2 . 12,13 The EL from the device based on the rutile TiO 2 , which is of technological significance, has not been realized to date. For the formation of rutile TiO 2 at low temperatures, etching of titanium (Ti) in combination with subsequent oxidation has been proved to be a feasible strategy.…”

Photoluminescence Spectroscopic Studies on TiO2 Photocatalyst

“…In the study of pristine anatase, Mochizuki and co-workers reported that the broad visible luminescence band was originated from the surface oxygen defects (Mochizuki et al 2003). Fernández et al (2005) also observed a complex visible band in different surface orientations of TiO 2 single crystals by the cathodoluminescence spectra and ascribed it to oxygen vacancies accompanied with the formation Ti 3+ . For rutile TiO 2 , a near-infrared luminescence band peaked at about 830 nm has been reported.…”

“…The photoluminescence wavelength of TiO 2 depends on its crystal structure and its particle size, while the photoluminescence intensity depends on the dopants, annealing temperatures and atmospheric conditions during the crystallization of TiO 2 , and the ambient temperature and atmospheric environments during the photoluminescence measurements. The main features of TiO 2 are the broad and structureless visible or near-infrared luminescence bands (Anpo et al 1985a(Anpo et al , b, 1989(Anpo et al , 1991Serpone et al 1995;Tang et al 1993Tang et al , 1994bZhang et al 2000a, b;Montoncello et al 2003;Mochizuki et al 2003;Poznyak et al 1992;Hachiya and Kondoh 2003;Nakato et al 1983Nakato et al , 1986Nakato et al , 1997Grabner et al 1970;Ghosh et al 1969;Fernández et al 2005;Plugaru et al 2004;de Haart and Blasse 1986;Forss and Schubnell 1993;Lei et al 2001;Qian et al 2005;Knorr et al 2008).…”

“…For rutile TiO 2 , a near-infrared luminescence band peaked at about 830 nm has been reported. The luminescence centers of this near-infrared band were identified as the Cr 3+ impurities (Grabner et al 1970;Haart et al 1986), though many other researchers attributed it to the interstitial Ti 3+ ions (Fernández et al 2005;Plugaru et al 2004;Ghosh et al 1969). In the photoluminescence spectra of rutile electrode in aqueous electrolyte solutions, the near-infrared luminescence band was attributed to the intermediate species generated during the photooxidation reaction of water (Nakato et al 1983(Nakato et al , 1986(Nakato et al , 1997.…”