R 3 Mn 1.5 CuV 0.5 O 9 (R= Y, Ho, Er, Tm, Yb and Lu) and Lu 3 Mn 33x Cu 2x V x O 9 : New noncentrosymmetric oxides related to YMnO 3 K.P. Surendran a , Rohini Mani a , J. Gopalakrishnan a , K.V. Ramanujachary b, * , S.E. Lofland c , William L. Green b a Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India b Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, USA c Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, USA Received 9 July 2006; accepted 10 August 2006 Available online 22 September 2006 Abstract We report formation of new noncentrosymmetric oxides of the formula, R 3 Mn 1.5 CuV 0.5 O 9 for R =Y, Ho, Er, Tm, Yb and Lu, possessing the hexagonal RMnO 3 (space group P6 3 cm) structure. These oxides could be regarded as the x = 0.5 members of a general series R 3 Mn 33x Cu 2x V x O 9 . Investigation of the Lu–Mn–Cu–V–O system reveals the existence of isostructural solid solution series, Lu 3 Mn 33x Cu 2x V x O 9 for 0 < x  0.75. Magnetic and dielectric properties of the oxides are consistent with a random distribution of Mn 3+ , Cu 2+ and V 5+ atoms that preserve the noncentrosymmetric RMnO 3 structure. # 2006 Elsevier Ltd. All rights reserved. Keywords: A. Oxides; B. Chemical synthesis; C. X-ray diffraction; D. Magnetic properties 1. Introduction YMnO 3 and several RMnO 3 (R = heavy lanthanides) oxides crystallize in a noncentrosymmetric (space group P6 3 cm) structure (Fig. 1) where trigonal bipyramids of MnO 5 share corners forming layers which are separated by Y/R atoms [1]. These oxides are multiferroic magnetoelectric materials showing both ferroelectric (T c  570–990 K) and antiferromagnetic (T N  70–130 K) properties [2]. There is a great current interest in RMnO 3 oxides as multiferroic materials where more than one ferroic property coexist in the same material [3,4]. Concurrent with the efforts to understand and realize multiferroic properties in this group of oxides, efforts are also directed toward syntheses of new oxides of RMnO 3 structure. A series of oxides related to this structure is R 1+n Cu n M 3+n O 3+3n , where R = La, M = Mo 6+ or V 5+ members. La 4 Cu 3 MoO 12 (n = 3) and La 3 Cu 2 VO 9 (n = 2) adopt YMnO 3 related structures [5–7], but the triangular clustering of Cu 2+ and the overall long range ordering of Cu 2+ /Mo 6+ and Cu 2+ /V 5+ lead to centrosymmetric (P112 1 /m and P6 3 /m) superstructures related to YMnO 3 . However, R 2 CuTiO 6 (R = Y, Tb–Lu) where Cu 2+ and Ti 4+ are randomly distributed at the Mn 3+ site retain the noncentrosymmetric YMnO 3 structure [8]. www.elsevier.com/locate/matresbu Materials Research Bulletin 42 (2007) 618–625 * Corresponding author. Tel.: +1 856 256 5451; fax: +1 856 256 4478. E-mail address: chary@rowan.edu (K.V. Ramanujachary). 0025-5408/$ – see front matter # 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.materresbull.2006.08.016