Abnormal Raman spectra in Er-doped BaTiO3 ceramics

• Published in: Journal of Raman spectroscopy 2014-10, Vol.45 (10), p.963-970
• Main Authors: Lu, Da-Yong, Cheng, Wei, Sun, Xiu-Yun, Liu, Qiao-Li, Li, De-Xu, Li, Zhong-Yu
• Format: Article
• Language: English
• Subjects: abnormal Raman spectroscopy; electron paramagnetic resonance; erbium-doped barium titanate; fluorescence; site occupation
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.4575

Greatly enhanced and abnormal Raman spectra were discovered in the nominal (Ba1 − xErx)Ti1 − x/4O3 (x = 0.01) (BET) ceramic for the first time and investigated in relation to the site occupations of Er3+ ions. BaTiO3 doped with Ti‐site Er3+ mainly exhibited the common Raman phonon modes of the tetragonal BaTiO3. Er3+ ions substituted for Ba sites are responsible for the abnormal Raman spectra, but the formation of ErBa•−ErTi' defect complexes will decrease spectral intensity. A large increase in intensity showed a hundredfold selectivity for Ba‐site Er3+ ions over Ti‐site Er3+ ions. A strong EPR signal at g = 1.974 associated with ionized Ba vacancy defects appeared in BET, and the defect chemistry study indicated that the real formula of BET is expressed by (Ba1 − xEr3x/4)(Ti1 − x/4Erx/4)O3. These abnormal Raman signals were verified to originate from a fluorescent effect corresponding to 4S3/2→4I15/2 transition of Ba‐site Er3+ ions. The fluorescent signals were so intense that they overwhelmed the traditional Raman spectra of BaTiO3. The significance is that the abnormal Raman spectra may act as a probe for the Ba‐site Er3+ occupation in BaTiO3 co‐doped with Er3+ and other dopants. A new broad EPR signal at g = 2.23 was discovered, which originated from Er3+ Kramers ions. Copyright © 2014 John Wiley & Sons, Ltd. Greatly enhanced and abnormal Raman spectra are discovered in Er‐doped BaTiO3 ceramics, and a large increase in intensity shows a hundredfold selectivity for Ba‐site Er3+ ions over Ti‐site Er3+ ions. The abnormal Raman spectra originate from a fluorescent effect. A strong EPR signal at g = 1.974, which originates from ionized Ba vacancy defects, was discovered in Er‐doped BaTiO3 ceramic. A new broad EPR signal at g = 2.23 possibly arises from Er3+ (4f11, 4I15/2) Kramers ions.