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Hexagonal BaTiO 3 :Eu 3+ Nanoparticles: A Kinetically Stable Phase Prepared at Low Temperatures
Author(s) -
Patel Dinesh K.,
Vishwanadh Bathula,
Sudarsan Vasanthakumaran,
Vatsa Rajesh K.,
Kulshreshtha Shailendra K.
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.04077.x
Subject(s) - hexagonal phase , materials science , luminescence , ionic radius , nanoparticle , phase (matter) , barium titanate , crystallography , analytical chemistry (journal) , ion , nanotechnology , hexagonal crystal system , chemistry , dielectric , optoelectronics , organic chemistry , chromatography
Nanoparticles of Eu 3+ ‐doped BaTiO 3 having a hexagonal structure, which is a thermodynamically stable phase above 1432°C, have been prepared at a low temperature of 110°C based on the coprecipitation of Ti 4+ , Ba 2+ , and Eu 3+ in ethylene glycol medium by adding urea. Based on differential thermal analysis studies, it is inferred that the as‐prepared hexagonal phase of BaTiO 3 :Eu 3+ is unstable and decomposes to the anatase form of TiO 2 and barium carbonate above 420°C. Luminescence properties of the hexagonal form of BaTiO 3 :Eu 3+ nanoparticles have been compared with cubic BaTiO 3 :Eu 3+ nanoparticles prepared by the combustion method. Based on the detailed luminescence studies of Eu 3+ in both cubic and hexagonal form of BaTiO 3 samples, it is inferred that Eu 3+ ions mainly occupy the Ti 4+ sites in hexagonal BaTiO 3 and both Ba 2+ and Ti 4+ sites in cubic BaTiO 3 . A comparison of the luminescence properties of Eu 3+ in hexagonal and cubic form of BaTiO 3 suggested that there is increased distortion around Eu 3+ in hexagonal BaTiO 3 phase compared with cubic BaTiO 3 phase, and this has been explained in terms of the distorted environment created around larger ionic radii Eu 3+ ions occupying the smaller ionic radii Ti 4+ site. There is a significant difference in the decay constant for 5 D 0 level of Eu 3+ for these two forms of BaTiO 3 :Eu 3+ nanoparticles.