Bi{sub 4}LnNb{sub 3}O{sub 15} (Ln = La, Pr, Nd) and Bi{sub 4}LaTa{sub 3}O{sub 15}: New intergrowth Aurivillius related phases
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012 (India)
- Laboratoire de Sciences des Procedes Ceramiques et Traitements de Surface (CNRS UMR 6638), Universite de Limoges, 123 Avenue Albert Thomas, F-87060 Limoges Cedex (France)
We describe the synthesis and characterization of new intergrowth Aurivillius related phases, Bi{sub 4}LnNb{sub 3}O{sub 15} (Ln = La, Pr, Nd) and Bi{sub 4}LaTa{sub 3}O{sub 15}. Both powder X-ray diffraction and electron microscopy investigations show that the compounds adopt orthorhombic structures with the cell parameters a {approx} 5.5 A, b {approx} 5.5 A and c {approx} 20.9 A, suggesting an ordered intergrowth structure that consists of n = 1 [Bi{sub 2}NbO{sub 6}]{sup -} and n = 2 [Bi{sub 2}LnNb{sub 2}O{sub 9}]{sup +} Aurivillius fragments which are stacked alternately along the c-axis. The oxides do not show a second harmonic generation (SHG) response toward 1064 nm laser radiation; they do not show a ferroelectric-paraelectric transition either between 30 and 900 deg. C in dielectric measurements, indicating a centrosymmetric structure. Optical absorption studies show that the intergrowth phases possess considerably smaller band gaps than the parent Nb{sub 2}O{sub 5} and Ta{sub 2}O{sub 5}.
- OSTI ID:
- 20889779
- Journal Information:
- Materials Research Bulletin, Vol. 40, Issue 6; Other Information: DOI: 10.1016/j.materresbull.2005.03.005; PII: S0025-5408(05)00080-2; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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