L Journal of Alloys and Compounds 316 (2001) L4–L6 www.elsevier.com / locate / jallcom Letter Single crystal investigation of the binary NdB compound 4 a,b, a c a * P. Salamakha , A.P. Gonc ¸alves , O. Sologub , M. Almeida a ´ ´ ´ Departamento de Quımica, Instituto Tecnologico e Nuclear, P-2686-953 Sacavem, Portugal b NIRIM,1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan c Department of Quantum Matter, ADSM, Hiroshima University,1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan Received 20 November 2000; accepted 4 December 2000 Abstract 3 ˚ ˚ ˚ The crystal structure of the binary boride NdB , ( P4 / mbm space group, a57.1775(3) A, c54.0996(2) A, Z52, V5211.20(1) A , 4 23 21 r 54.070 g3cm , m 512.70 mm , R50.0378, wR2 50.0945 for 371 reflections with F . 4s( F )), was determined from single crystal o o X-ray diffraction (diffractometer Enraf-Nonius CAD-4, Mo Ka-radiation). The compound was found to crystallize with the ThB 4 structure type.  2001 Elsevier Science B.V. All rights reserved. Keywords: Rare earth compounds; Crystal structure; X-ray diffraction 1. Introduction X-ray single crystal diffraction data were obtained using a four circle diffractometer Enraf-Nonius CAD-4 with During the study of ternary rare earth metal boride graphite monochromatized Mo Ka radiation ( l 50.71073 systems, we were faced with uncertainties on the com- ˚ A). The least square refinements of the 2 u values of 25 position and solid solubility in some binary systems strong and well-centred reflections from the various re- reported earlier. The phase diagram for the binary Nd–B system was previously presented by Spear [1]. Four phases, Nd B , NdB , NdB and NdB , were identified in Table 1 2 5 4 6 66 Parameters for the single crystal X-ray data collection this system. However, the crystal structures of these phases were only partially studied by X-ray powder diffraction. Crystal formula NdB 4 Formula weight 187.48 g / mol In this paper we present the results of crystal structure Crystal system Tetragonal determination of the NdB compound, performed by single 4 Space group [11] P4 / mbm (No. 127) crystal X-ray diffraction. ˚ Lattice parameters, A a 7.1775(3) c 4.0996(2) 3 ˚ Cell volume, A 211.20(1) 2. Experimental details 23 Calculated density, g cm 4.070 21 Linear absorption coefficient (mm ) 12.70 The binary sample, with a total weight of 2 g, was ˚ Radiation, wavelength Mo Ka, 0.71073 A synthesized by arc melting the proper amounts of the Monochromator Graphite constituent elements under high purity argon on a water- Temperature 295 K 2u 79.89 cooled copper crucible. The starting materials (with purity max v 2 2u scan Dv 5 0.80 1 0.35 tan u higher than 99.9%) were used in the form of ingots. The Data set 212#h #12, 212#k #12, 27#l #7 weight losses during melting were less than 2%. Number of measured reflections 5204 A single crystal suitable for the X-ray measurements Number of unique reflections 388 was isolated from the surface of the sample, glued on the Number of reflections with F . 4s(F ) 371 o o Number of refined parameters 19 top of a glass fiber and mounted on a goniometer head. R, wR2 0.0378, 0.0945 Goodness of fit 1.131 *Corresponding author. Structure solution program SHELXL-97 E-mail address: salam@nirim.go.jp (P. Salamakha). 0925-8388 / 01 / $ – see front matter  2001 Elsevier Science B.V. All rights reserved. PII: S0925-8388(00)01498-5