Magnetic ordering of anti-Th 3 P 4 -type R 4 X 3 and Th 3 P 4 -type R 3 X 4 compounds (R ¼ Ce, Pr, Nd, Sm, X ¼ Ge, Sb, Te) A.V. Morozkin a, * , R. Nirmala b , O. Isnard c, d , S.K. Malik e , Jinlei Yao f , Yu. Mozharivskyj f , S.A. Granovsky g a Department of Chemistry, Moscow Lomonosov State University, Moscow, Russia b Indian Institute of Technology Madras, Chennai 600 036, India c Institut Laue-Langevin, 6 Rue J. Horowitz, 38042 Grenoble, France d Institut Néel du CNRS et Université J.Fourier, Avenue des martyrs BP166X, 38042 Grenoble, France e International Institute of Physics (IIP)-UFRN, Natal, 59072-970, Brazil f Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 g Moscow State University, Faculty of Physics, Leninskie Gory GSP-1,119991 Moscow, Russia article info Article history: Received 20 April 2011 Received in revised form 15 July 2011 Accepted 18 July 2011 Available online 28 August 2011 Keywords: A. rare-earth intermetallics B. magnetic properties F. diffraction (neutron) abstract The Th 3 P 4 -type Ce 3 Te 4 and Nd 3 Te 4 compounds (space group I 4 3d,N  220) have been investigated by means of magnetization and neutron powder diffraction. The magnetization measurements indicate that Ce 3 Te 4 and Nd 3 Te 4 order ferromagnetically at w5 K and w38 K. Neutron diffraction experiments in zero fields show that below their magnetic transition temperatures the Ce 3 Te 4 and Nd 3 Te 4 compounds exhibit a collinear ferromagnetic type ordering with the C 3v magnetic point group (wave vector K 0 ¼ [0, 0, 0]). Magnetic moment values of 0.66(6) m B /Ce and 2.4 m B /Nd are obtained from the analysis of neutron diffraction data at 1.5 K for Ce 3 Te 4 and Nd 3 Te 4 . The earlier reported magnetic structures of the anti-Th 3 P 4 - type Ce 4 Ge 3 , Ce 4 Sb 3 , Pr 4 Sb 3 and Nd 4 Sb 3 compounds were re-refined and re-assigned in terms of magnetic point groups. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction It is known that the R 4 X 3 and R 3 X 4 compounds with the cubic anti-Th 3 P 4 -type and Th 3 P 4 -type structures (cI28, space group II 4 3d, N  220) can be formed with R ¼ rare-earth elements and X ¼ Ge, Sn, As, Sb, Bi and Te [1]. The magnetic properties and magnetic struc- tures of anti-Th 3 P 4 -type R 4 X 3 compounds (R ¼ Ce, Pr, Nd, Sm, X ¼ Ge, Sb) with the rare-earth atoms at the 16c site were reported in Refs [3e5]. The Ce 4 Sb 3 [3] and Ce 4 Ge 3 [4] compounds order antiferromagneticly (AF) in zero applied magnetic field but undergo field-induced transitions into a ferromagnetic (F) state in a small critical field H C w 0.1 T Pr 4 Sb 3 demonstrates a mixed AF-F ordering, whereas Nd 4 Sb 3 shows a high-temperature ferromag- netic ordering and a low-temperature AF-F ordering in zero field [5]. In this work, the magnetic properties and structures of the Th 3 P 4 -type R 3 Te 4 compounds (the R atoms at the 12a sites) have been investigated. The current study allows to understand and classify the magnetic ordering of anti-Th 3 P 4 -type and Th 3 P 4 -type compounds in term of the crystal symmetry and magnetic point group symmetry. 2. Experimental The Ce 3 Te 4 and Nd 3 Te 4 samples were prepared in an electric arc furnace under an argon atmosphere using a non-consumable tungsten electrode and a water-cooled copper hearth. The tellu- rium (99.99 wt. %), cerium (99.9 wt. %) and neodymium (99.9 wt. %) were used as the starting materials. Zirconium was used as a getter during the melting process. The sample’s composition and purity was checked using a quantitative electron probe microanalysis (“Camebax” micro- analyser, 15 kV, 3  10 8 A, K-, L- and M- lines, 2  2 micron 2 ) and X-ray powder diffraction (DRON-3 diffractometer, Cu K a - radiation, 2q ¼ 20e70 deg, step 0.05 deg, 1002 points). The microprobe analysis show that the samples contain 43  1 at % of rare earth and 57  1 at % of tellurium. The lattice and atomic parameters of Ce 3 Te 4 and Nd 3 Te 4 were refined using the Rietan- programs [6]. The neutron powder diffraction was carried out from w90 K down to 1.5 K in zero magnetic field at the Institute Laue- Langevin, Grenoble, France, using the powder diffractometer D1B [7], operating at a wavelength l ¼ 0.252 nm. The magnetic * Corresponding author. E-mail address: morozkin@general.chem.msu.ru (A.V. Morozkin). Contents lists available at ScienceDirect Intermetallics journal homepage: www.elsevier.com/locate/intermet 0966-9795/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.intermet.2011.07.019 Intermetallics 19 (2011) 1794e1803