Crystal Structures, Physical Properties and NMR Experiments on the Ternary Rare-Earth Metal Silicide Boride Compounds RE5Si~2B8 (RE = Y, Sm, Gd, Tb, Dy, Ho).

Roger, J. and Babizhetsky, V. and Cordier, S. and Bauer, J. and Hiebl, K. and Le Pollès, L. and Ashbrook, S. E. and Halet, J. F. and Guerin, R. (2005) Crystal Structures, Physical Properties and NMR Experiments on the Ternary Rare-Earth Metal Silicide Boride Compounds RE5Si~2B8 (RE = Y, Sm, Gd, Tb, Dy, Ho). Journal of Solid State Chemistry, 178. pp. 1851-1863. DOI 10.1016/j.jssc.2005.02.023

[img] PDF
Crystal_structures_-_Ashbrook.pdf
Restricted to Registered users only

Download (686kB)

Abstract

The ternary rare-earth metal silicide borides RE5Si2B8 (RE ¼ Y, Sm, Gd, Tb, Dy Ho) were prepared by arc melting the elemental components and subsequent annealing up to T ¼ 1850 K. The crystal structure was determined for each term of the series from single-crystal X-ray data: tetragonal symmetry, space group P4/mbm, Z ¼ 2; unit cell parameters a ¼ 7:2616ð3Þ, c ¼ 8:2260ð3Þ (A and a ¼ 7:1830ð2Þ, c ¼ 7:9900ð3Þ (A for Sm5Si2B8 and Ho5Si2B8, respectively. The structure is a new type and can be structurally described as an intergrowth of ThB4-like and U3Si2-like slabs of composition REB4 and RE3Si2, respectively, alternating along the c direction. The boron and silicon substructures are wholly independent and well ordered. The magnetic properties are as follows: Y5Si2B8 is a Pauli-type paramagnet above 1.8 K, Gd5Si2B8 undergoes a weak (canted) ferromagnetic-like order at 70K followed by a colinear antiferromagnetic spin alignment at 44 K. Tb5Si2B8 and Dy5Si2B8 order antiferromagnetically at a Ne´ el temperature of TN ¼ 45 and 28 K, respectively. In the paramagnetic regime, the effective moments are in good accord with the theoretical RE3+ free ion moments. The temperature dependence of the electrical resistivities for the Y, Gd, Tb, and Dy containing samples corroborates with the metallic state of the nonmagnetic (Y) and the magnetically ordered compounds. 11B, 29Si and 89Y nuclear magnetic resonance (NMR) spectroscopy on nonmagnetic Y5Si2B8 shows different signals, which correspond to the expected number of distinct crystallographic sites in the structure. 11B NMR on Y5Si2B8 indicates that the local magnetic susceptibilities are substantially different from the ones observed in the related compound YB4.

Item Type: Article
Uncontrolled Keywords: 2005 AREP 2005 P IA48
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: Journal of Solid State Chemistry
Volume: 178
Page Range: pp. 1851-1863
Identification Number: 10.1016/j.jssc.2005.02.023
Depositing User: Sarah Humbert
Date Deposited: 19 Aug 2010 09:11
Last Modified: 23 Jul 2013 09:59
URI: http://eprints.esc.cam.ac.uk/id/eprint/1802

Actions (login required)

View Item View Item

About cookies