Ternary Rare-Earth Iron Arsenides RE₁₂Fe_57.5As₄₁ (RE = La, Ce)

Abstract

The rare-earth iron arsenides RE(12)Fe(57.5)As(41) (RE = La, Ce) have been prepared by direct reactions of the elements in the presence of a Sn flux. Analysis of single-crystal X-ray diffraction data reveals that they adopt a new orthorhombic structure type (Pearson symbol oP236, space group Pmmn, Z = 2; a = 10.8881(9) A, b = 25.753(2) A, c = 12.5436(10) A for RE = La; a = 10.8376(8) A, b = 25.639(2) A, c = 12.4701(9) A for RE = Ce). In this metal-rich arsenide, the complex three-dimensional network (derived from 4 RE, 24 Fe, and 17 As sites) can be described as being built from unusual wavelike layers of connected As-centered trigonal prisms. Five of the Fe sites are partially occupied. The electronic structure of these compounds was probed through core-line X-ray photoelectron spectra. Magnetic susceptibility measurements indicated ferromagnetic ordering at T(C) = 125 and 95 K for the La and Ce compounds, respectively. Electrical resistivity measurements on single crystals of Ce(12)Fe(57.5)As(41) showed metallic behavior with a prominent transition that coincides closely with the ferromagnetic ordering temperature.

Synthesis, and Crystal and Electronic Structures, of the Titanium-Rich Bismuthides AE3Ti8Bi10 (AE = Sr, Ba, Eu)

“…Combinations of distinct chemical bonding not only provide conditions for realization of varying crystal structures but can also engender notable structural complexity. − The interplay of chemical composition and peculiar bonding frequently gives rise to interesting properties in TM pnictides. Some of these compounds have been proposed as potential thermoelectric materials, because of their appropriate electronic properties, coupled with low thermal conductivity, e.g., Yb 14 MnSb 11 or A TM 4 Pn 12 , where A is an alkali, alkaline-earth, or rare-earth metal .…”

Study on High-Temperature Interaction Mechanism of Nd–Fe–As System

“…An undetermined diffraction peak is also observed in the XRD pattern. According to the results of EDS analysis and the literature report of Stoyko, the unknown diffraction peak may be the ternary compound RE 12 Fe 57.5 As 41 [14].…”

“…With decreasing temperature, the solubility of As in Fe decreases gradually, and the solubility of As in Fe is less than 5% at room temperature [11,12,13]. Different atomic ratios of cerium (lanthanum), Fe, and As can form the ternary compounds RE 12 Fe 57.5 As 41 (RE=La, Ce) and FeAs at 1173 K [14,15]. The ternary compound La 10 Fe 50 As 40 is formed by the La–As–Fe system at 1223 K [16].…”

Study on Interaction Mechanism of Different Atomic Ratio of Neodymium, Arsenic and Iron

“…As form the ternary compound RE12Fe57.5As41 (RE=La, Ce) and FeAs at 1173 K [13][14] , whereas the Re-Fe-As ternary system forms La10Fe50As40 15 at 1223 K. In recent years, one of products of RE-Fe-As ternary system named EuFe2As2 [16][17][18][19][20] has attracted significant attention. Xie 21 and Fu 22 investigated the interaction of Nd-Fe-As system at high temperatures and found that the formation of the ternary compound NdFeAs depends on the formation of NdAs and FeAs2.…”