The crystal structural of the Er10Ga3Si3 ternary compounds

Abstract

s. A ternary compound Er10Ga3Si3 was synthesized and studied by means of X-ray powder diffraction technique using Rietveld methods. The ternary compound Er10Ga3Si3 crystallizes in the hexagonal structure, space group P63/mcm (N0.193) with the Mn5Si3 structure type and lattice parameters a= 8.3595(1)Ǻ, c=6.3095(1)Ǻ, V = 381.84A, z=1 and ρx=8.55 g/cm. Introduction Searching for novel compounds, especially rare earth compounds, with excellent properties is very important for developing new potential function materials. Compounds with the Mn5Si3-type structure have been sources of useful chemical instruction as well as of significant experimental errors, both deriving from a remarkable flexibility of this particular structure type to accommodate a great range of host substitutions as well as to bind diverse interstitials [1-2]. In the R-Ga-Si ternary system, the crystal structures of REGaxSi2-x-y (RE=Ho, Er, Tm; 0.33≤ x ≤0.40, 0.10≤ y ≤0.18) [3], EuGaSi [4], Ga1.34NdSi0.66 and NdGa0.86Si1.14 [5] have been reported. To the best of our knowledge, ternary intermetallic compound Er10Ga3Si3 have not been reported in literature. This work reports on the crystal structure of Er10Ga3Si3. Experimental details The sample of Er10Ga3Si3 with a total mass of 2 g was prepared by arc melting using a nonconsumable tungsten electrode and a water-cooled copper tray under argon atmosphere. Erbium (purity of 99.9%), gallium (purity of 99.9%), and silicon (purity of 99.999%) were used as the starting materials. Titanium was used as an oxygen getter during the melting process. The sample was remelted three times in order to ensure the complete fusion and homogeneity. The weight loss during melting was less than 1%. Following the melting, the ingot was wrapped in a tantalum foil, sealed under vacuum in a silica tube and annealed at 1123 K for 4 weeks, then cooled down at a rate of 10 K/h to room temperature. The sample was ground in an agate mortars and pestled to particle sizes of no larger than 45 μm. High-quality powder X-ray diffraction patterns of the sample were collected at room temperature using a Rigaku Smart Lab 2006 powder diffractometer equipped with a Cu Kα radiation (40kV, 150mA) and a graphite monochromator. The scan range was from 10.00 o to 100.00 o (2θ) with a step size of 0.02 o and a count time of 1 s per step. Results and discussion The powder X-ray diffraction pattern of Er10Ga3Si3 was successfully indexed using the Jade 5.0 [6] program in a hexagonal unit cell with the lattice parameters a= 8.3595(1)Ǻ, c=6.3095(1)Ǻ. Reflection conditions ( h h0l : l = 2n, 000l : l = 2n) pointed to 3 space groups P63/mcm (No. 193), p 6c2 (No. 188) and P63cm (No. 185) [7]. By comparing crystallographic characteristics of the Er10Ga3Si3 compound with those presented in the structure type database, it was found that Er10Ga3Si3 and Mn5Si3 [8] have the same structure type (space group P63/mcm). So the space group P63/mcm (No.193) and the atomic position parameters of Mn5Si3 were taken as the starting 5th International Conference on Information Engineering for Mechanics and Materials (ICIMM 2015) © 2015. The authors Published by Atlantis Press 800 values to refine the structural parameters of Er10Ga3Si3. Structure refinement of Er10Ga3Si3 was then performed using the DBWS9807 program [9]. The Er sites corresponded to the Mn sites, and both Ga and Si occupied the Si site in Mn5Si3. When the 6 (g) site occupied by 50% Ga and 50% Si, the goodness-of-fit parameters of these refinements led to the best values: Rp=8.97%, Rwp=12.03%, RB=6.42%, RF=4.27%. The details of the Rietveld refinement of Er10Ga3Si3 are summarized in Table 1, and the atomic positions and thermal displacement factors are presented in Table 2. The observed, calculated, and residuals X-ray powder diffraction patterns of Er10Ga3Si3 are shown in Figure. 1. A set of interatomic distances in Er10Ga3Si3 are given in Table 3. The crystal structure of the Er10Ga3Si3 compound is shown in Figure 2. Fig.1. Observed, calculated and residuals X-ray powder diffraction patterns of Er10Ga3Si3 Fig.2. Crystal structure of the Er10Ga3Si3 compound (M=50% Ga+50% Si)