We describe the synthesis and characterization of new intergrowth Aurivillius related phases, Bi(4)LnNb(3)O(15) (Ln = La, Pr, Nd) and Bi4LaTa3O15. Both powder X-ray diffraction and electron microscopy investigations show that the compounds adopt orthorhombic structures with the cell parameters a similar to 5.5 angstrom, b similar to 5.5 angstrom and c similar to 20.9 angstrom, suggesting an ordered intergrowth structure that consists of n = 1 [Bi2NbO6](-) and n = 2 [Bi(2)LnNb(2)O(9)](+) 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 T in dielectric measurements, indicating a centrosymmetric structure. Optical absorption studies show that the intergrowth phases possess considerably smaller band gaps than the parent Nb2O5 and Ta2O5. (c) 2005 Elsevier Ltd. All rights reserved.