Optical absorption of electronic defects and chemical diffusion in vapor transport equilibrated lithium niobate at high temperatures

Autor:	Günter Borchardt, Holger Fritze, Claudia Swanson, Klaus-Dieter Becker, Anke Weidenfelder, Peter Fielitz, Jianmin Shi
Rok vydání:	2014
Předmět:	Diffusion Lithium niobate Inorganic chemistry Niobium Analytical chemistry chemistry.chemical_element General Chemistry Partial pressure Condensed Matter Physics Ion chemistry.chemical_compound chemistry General Materials Science Spectroscopy Absorption (electromagnetic radiation) Single crystal
Zdroj:	Solid State Ionics. 262:904-907
ISSN:	0167-2738
DOI:	10.1016/j.ssi.2013.11.025
Popis:	Optical absorption of electronic defects induced by chemical reduction, and chemical diffusion in a vapor transport equilibrated lithium niobate single crystal with 49.5 mol% Li 2 O were studied using UV–vis-NIR optical spectroscopy under in situ conditions. In reducing atmospheres at 1000 °C, optical absorption spectra are dominated by a band at about 0.93 eV which is attributed to absorption of free electron-polarons, i.e., to electrons localized on niobium ions on regular lattice sites. The electron-polaron band intensity was found to follow a power law of the form (pO 2 ) m with m ≈ − 0.21. Chemical reduction reactions forming free electron-polarons were found to explain the observed defect absorption and its dependence on oxygen partial pressure at high temperatures. The chemical diffusion coefficient in the vapor transport equilibrated lithium niobate has been determined to be 2.75 × 10 − 11 m 2 /s at 1000 °C from the kinetics of reduction and oxidation processes in the range of − 10 log p O 2 / atm
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::57dd5739f76e14703e1dd022fd74f7e0 https://doi.org/10.1016/j.ssi.2013.11.025 Zobrazit plný text záznamu Full Text from ScienceDirect