Local A‐Site Layering in Rare‐Earth Orthochromite Perovskites by Solution Synthesis

Abstract

Cation size effects were examined in the mixed A‐site perovskites La0.5Sm0.5CrO3 and La0.5Tb0.5CrO3 prepared through both hydrothermal and solid‐state methods. Atomically resolved electron energy loss spectroscopy (EELS) in the transmission electron microscope shows that while the La and Sm cations are randomly distributed, increased cation‐radius variance in La0.5Tb0.5CrO3 results in regions of localised La and Tb layers, an atomic arrangement exclusive to the hydrothermally prepared material. Solid‐state preparation gives lower homogeneity resulting in separate nanoscale regions rich in La3+ and Tb3+. The A‐site layering in hydrothermal La0.5Tb0.5CrO3 is randomised upon annealing at high temperature, resulting in magnetic behaviour that is dependent on synthesis route.

Mild Hydrothermal Crystallization of Heavy Rare-Earth Chromite RECrO3 (RE = Er, Tm, Yb, Lu) Perovskites and Magnetic Properties

“…The crystallites obtained by this method, however, are agglomerated . They also demonstrated that hydrothermal method is more effective for the preparation of atomic-scale homogeneous distribution of mixed A-site cations than the high-temperature calcination method with the same compositions . Recently, Xu et al reported a continuous supercritical hydrothermal flow method to synthesize of LaCrO 3 nanoparticles, which means this family of materials can be produced via a continuous fabrication based on hydrothermal technique.…”

Correlating the Influence of Two Magnetic Ions at the A-Site with the Electronic, Magnetic, and Catalytic Properties in Gd1–xDyxCrO3

“…14−18 Studies dealing with sharing of the A-site with one magnetic ion (such as Gd or Pr) and the other nonmagnetic ion (La or Y) are quite common, whereas similar investigations with the A-site shared by magnetic rare earths are limited. 19−29 Also, in such studies, the effects of only a smaller concentration of the second magnetic rare-earth ion (typically up to 10%) have been focused. These studies employed the solid-state diffusion process for preparing the samples.…”

“…Perovskite structure with the general formula ABX 3 is very popular among solid-state chemists, condensed matter physicists, and materials scientists and has been investigated extensively. − The innumerable number of possibilities of substitutions at A and B sites with ions of varying valence and ionic radii together with the choice of anion from halide to oxide adore it to exhibit many interesting properties such as high-temperature superconductivity, piezoelectricity, ferroelectricity, multiferroism, colossal magneto resistance, and catalytic functions. − The recent demonstration of high solar cell capability in organic–inorganic halo perovskites has added a new dimension to the expanding list of multifunctions that one can anticipate to be discovered. , The multifunctional character of rare-earth chromites (RECrO 3 ) with a distorted perovskite structure has invited extensive investigation by the research community with special emphasis on the rare earths, influencing a possible magneto-electric coupling. ,− Essentially, three different magnetic spin interactions, Cr 3+ –Cr 3+ , Cr 3+ –RE 3+ , and RE 3+ –RE 3+ , with isotropic, symmetric, and antisymmetric anisotropic exchange, respectively, exist in these systems. − The antiferromagnetic Neel temperature ( T N ) arising from Cr 3+ –Cr 3+ interactions has been found to increase with increase in the ionic radius of rare-earth (RE 3+ ), illustrating the influence of the A-site ion on the ordering of B-site ions. A lot of deliberations have been found to dominate the current literature, seeking the exact role of magnetic RE 3+ for the observed canted antiferromagnetism and polarization in these systems. − Studies dealing with sharing of the A-site with one magnetic ion (such as Gd or Pr) and the other nonmagnetic ion (La or Y) are quite common, whereas similar investigations with the A-site shared by magnetic rare earths are limited. − Also, in such studies, the effects of only a smaller concentration of the second magnetic rare-earth ion (typically up to 10%) have been focused. These studies employed the solid-state diffusion process for preparing the samples …”

Physical properties of Nano Crystalline Ceramic HoBaCrO

“…In order to explain the asymmetric nature of peaks, the experimental data was fitted using the following modified KWW function suggested by Bergman [84] :…”