An ultra-high-entropy rare earth orthoferrite (UHE REO): solution combustion synthesis, structural features and ferrimagnetic behavior

Abstract

A solution combustion synthesis approach was used for the first time in the synthesis of chemically and phase-pure ferrimagnetic nanocrystals of an ultra-high-entropy rare earth orthoferrite (UHE REO).

Synthesis, structure and electrochemical performance of an ultra-high-entropy rare earth orthoferrite (UHE REO) for overall water splitting (OWS)

“…Additionally, the presence of diverse elemental metal natures in the sample mixture may hinder the crystalline phase's formation. Upon calcination at 800 °C for 4 hours, the characteristic peaks indicate a single phase corresponding to the known perovskite-like orthoferrite compound (∑REFeO 3 ) with an orthorhombic crystal structure (space group Pbnm ) 57 similar to the CIF file of COD ID 1008091 (Crystallography Open Database) for the perovskite-like o -TbFeO 3 compound. The Miller indices hkl are illustrated in Fig.…”

“…5b. The spectrum exhibits vibrational modes characteristic of the orthoferrite structure, 57 featuring seven first-order vibrations. Specifically, three strong A g modes are observed at 162, 289, and 421 cm −1 , three B 1g modes at 330, 476, and 560 cm −1 , and one B 2g mode at 227 cm −1 .…”

“…The UHE REO nanopowder was synthesized by the solution combustion method based on the redox reaction between glycine (reductant or fuel) and metal nitrates (oxidant), as previously reported. 57 The specific reagents are as follows: C 2 H 5 NO 2 , Fe(NO 3 ) 3 ·9H 2 O, Sc(NO 3 ) 3 ·4H 2 O, Y(NO 3 ) 3 ·6H 2 O, La(NO 3 ) 3 ·6H 2 O, Ce(NO 3 ) 3 ·6H 2 O, Pr(NO 3 ) 3 ·6H 2 O, Nd(NO 3 ) 3 ·6H 2 O, Sm(NO 3 ) 3 ·6H 2 O, Eu(NO 3 ) 3 ·6H 2 O, Gd(NO 3 ) 3 ·5H 2 O, Tb(NO 3 ) 3 ·5H 2 O, Dy(NO 3 ) 3 ·5H 2 O, Ho(NO 3 ) 3 ·5H 2 O, Er(NO 3 ) 3 ·5H 2 O, Tm(NO 3 ) 3 ·5H 2 O, Yb(NO 3 ) 3 ·5H 2 O, Lu(NO 3 ) 3 ·4H 2 O. All of the mentioned compounds were obtained from NevaReaktiv (Russia), were chemically pure (∼99%), and were used without further treatment.…”

“…For (R1), stands for the ratio of fuel to oxidants, where φ = 1.0 (stoichiometric) means the initial mixture doesn't require atmospheric oxygen for complete fuel oxidation, while φ < 1 and φ > 1 imply fuel-lean and fuel-rich conditions, respectively. 58 As a part of the ongoing research from our previous work, 57 φ = 2.0 was chosen as the optimal redox parameter for this work.…”

“…In this investigation, the authors propose a research direction centered on an ultra-high-entropy rare earth orthoferrite (denoted as UHE REO) encompassing all 16/17 rare earth elements in the Mendeleev periodic table. 57 This material is explored as a catalyst for water electrolysis, specifically for the OER and HER. To enhance the surface area and diminish the size of the resulting nanoparticles, a two-step combustion synthesis method was employed.…”