Crystallochemical, magnetic and electrical properties of the K2NiF4 type diluted solid solution Y0.9Ca1.1CryAl1 − yO4 − δ (y≤0.10): Evidence for a partial Cr3+ → Cr4+ oxidation

The solid solution Sr3Ti2-xFexO7-δ (x ≤ 0.5): characterization of Fe (III) – Fe (IV) mixed valences

“…As an example the existence of two P 2 /RS type iron strontium mixed oxide is reported, namely the Fe(IV) one Sr 3 Fe 2 O 7 [12] and the Fe(III) one Sr 3 Fe 2 O 6 [9]. Due to this and in the frame of our previous work on P/RS type chromium doped aluminates [15] and P 2 /RS chromium doped titanates [16], it was decided to look for compositions where it is possible to create mixed valence Fe(III) and Fe(IV) state of the iron atoms.…”

Synthesis by pyrolysis of aerosols and ceramic application of Cr-doped CaYAlO4 red–orange pigments

“…Such unusual variation is in agreement with previous reports in which it was associated to the simultaneous distortion of both the (Al,Cr)O 6 octahedra and the (Y,Ca)O polyhedra induced by the incorporation of Cr 3+ . 9,10,21 Finally, no appreciable changes in particle size and shape (Fig. 2C) were observed after heating at 1200 • C, but certain sintering process took place during this treatment.…”

“…[1][2][3][4][5] YCaAlO 4 belongs to the series of A 3+ B 2+ AlO 4 aluminates (A 3+ = Y, Nd, La; B 2+ = Ca, Sr), which crystallize in the K 2 NiF 4 type structure consisting of a 1/1 intergrowth of ABO 3 perovskite and AO rock-salt (NaCl) type layers connected by anisotropic A-O apical -B bridge bonds, where A and B elements present ninefold coordination whereas Al is octahedrally coordinated. 6,7 These complex oxides are versatile compounds which, when doped with different transition elements, result in materials with interesting electric, magnetic, [8][9][10] optical 11 and infrared 6 properties. In particular, it has been * Corresponding author.…”

“…Thus, whereas in the pioneering work by Olazcuaga et al, 11 a trivalent state was assumed, in further works, the possibility of a partial Cr 3+ -Cr 4+ oxidation was suggested. 7,9 Finally, the behaviour of 0955-2219/$ -see front matter © 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.jeurceramsoc.2009.01.020 this system, once applied in conventional industrial glazes, was assessed.…”

State of Chromium Atoms, Clustering, and Interatomic Interactions in Doped Lanthanum Gallate La(Sr)Ga(Cr,Mg)O3-δ

“…There is no doubt that in LaCr x Ga 1-x O 3 only Cr(III) is present, and since the isotherms for Cr:Sr = 5:1, and Cr:Sr:Mg = 5:1:1 coincide with the isotherms for LaCr x Ga 1-x O 3 over a wide range of concentrations we can suggest that chromium does not change its valence state and remains trivalent. Otherwise, if we had a partial or complete oxidation of Cr(III) to Cr(IV) in the systems with Sr and (or) Mg, the isotherms of magnetic [64].…”