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

Journal Article · Wed Jun 15 04:00:00 EDT 2005 · Materials Research Bulletin

DOI:https://doi.org/10.1016/j.materresbull.2005.03.005· OSTI ID:20889779

Mandal, Tapas Kumar ^[1]; Augustine, Saji ^[1]; Gopalakrishnan, J ^[1]; Boullay, Ph ^[2]

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1. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012 (India)
2. 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, Journal Name: Materials Research Bulletin Journal Issue: 6 Vol. 40; ISSN MRBUAC; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION
CHEMICAL PREPARATION
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
FERROELECTRIC MATERIALS
HARMONIC GENERATION
LASER RADIATION
NIOBATES
NIOBIUM OXIDES
OPTICAL PROPERTIES
ORTHORHOMBIC LATTICES
TANTALUM OXIDES
X-RAY DIFFRACTION