Refinement of Th₂Zn₁₇ structure: Pr₂Fe₁₇

Abstract

The phase, previously called PrFeT, has been reinvestigated by single-crystal X-ray diffraction methods using data obtained with a diffractometer and molybdenum radiation. As reported earlier, the compound is rhombohedral, space group R3m, with a=8.585, c= 12.464/~; contrary to earlier findings, it has the composition PrzFe17 and an ordered Th2Zn17-type structure. Ce, Nd and Sm in combination with Fe have all been reported previously to form the same structure as the Pr-Fe compound. The composition AB7 reported for these three phases is therefore in doubt. For AB~ compounds of the ThZns.5(ThzZn17) type, no conclusive crystallographic evidence has yet been put forth for x other than 8-5.

The effect of ball milling in the microstructure and magnetic properties of Pr2Fe17 compound

“…The values obtained are in perfect agreement with those reported in [1,11]. The R-factors obtained for the analysis reflects its satisfactory truthfulness (around 2% for both bulk and milled samples).…”

Magnetic properties and magneto-caloric effect in pseudo-binary intermetallic (Ce,R)2Fe17 compounds (R = Y, Pr and Dy)

“…This parameter is commonly calculated using three different criteria [see reference 7 for details], and hereafter we shall call them RCP-1, RCP-2 and RCP-3. They are defined as: RCP- In that phase the rare earth occupy the 6c site for pure R 2 Fe 17 alloys [30,31], and when mixing two different rare earth elements both occupy the same 6c crystallographic site. Hence, Ce stabilizes the rhombohedral phase although the hexagonal structure is more stable for the Y 2 Fe 17 and Dy 2 Fe 17 binary intermetallic compounds.…”

The effect of nitrogen insertion on the magnetic and structural properties of Sm2–xGdxFe17 alloys (0 ≤ x ≤ 2)

“…The analysis of the reasons of the enhancement of magnetic properties should be an important theme for understanding the magnetic properties of the rare earth-transition metal compounds including the third elements, such as N and C. The measured lattice expansion with the nitrogen uptake in the Sm 2 Fe 17 N 3 is about 6-7 vol% compared with the Sm 2 Fe 17 starting alloy [16,19], and the introduced nitrogen atoms occupy the 9e and/or 18g sites in the structure. The four iron sites exist in the Th 2 Zn 17 type structure of Sm 2 Fe 17 N x , and they can be categorized into the following two groups: the first nearest neighbours for the N(9e) sites are Fe (18h) and Fe (18f) sites in which the direct Fe-N hybridizations can be formed, and the second nearest neighbours for the N(9e) sites are Fe (6c) and Fe (9d) sites; they have the direct chemical bonds only between the surrounding Fe (18f) and Fe (18 h) sites [16,20,21]. It was revealed by neutron diffraction studies that the lattice expansion in the Th 2 Zn 17 type structure with the nitrogen uptake results in the expansion of Fe-Fe interatomic distances at the Fe sites, except the Fe (6c) site, at which the distances between the nearest neighbour Fe (18f) atoms show almost constant values before and after the nitrogen insertion into the structure [22].…”