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A nearly stoichiometric SrCoO3 phase had been prepared up to now only using high oxygen pressure. A new method for preparing fully stoichiometric SrCoO3 has been proposed using electrochemical oxidation. Brownmillerite‐type SrCoO2.50 is oxidized into a completely stoichiometric perovskite at a potential of 500 mV for 180 hours at room temperature in alkaline media (1 M KOH). The oxidized phase has a cubic unit cell (a=383.5 pm). It is metallic and, at temperatures below T=280 K, it shows ferromagnetic behavior. The magnetic moment at 0 K is 2.1 μB. The physical properties of SrCoO3.00 have been explained in terms of partial occupancy of a σ*e gα band.

The effectiveness of Raman spectroscopy (using a bench-top system on standard pigments) for the characterisation of modified lead antimonate yellows was demonstrated in the already published Part I. The knowledge gained is employed here for the study of yellow glazes on genuine Renaissance plates with the aim of identifying non-invasively lead pyroantimonate compounds by portable micro-Raman equipment. The investigation was carried out directly on site, at the Victoria and Albert Museum (London, UK) and at the Museo Statale d'Arte Medievale di Arezzo (Arezzo, Italy), combining Raman and X-ray fluorescence analyses. In addition to the spectral features of both unmodified Naples yellow and Sn-and Zn-modified lead antimonatecompounds, the Raman patterns related to partially modified pyrochlore structures were observed. For this reason, the possible Sn-induced modification of Naples yellow by cassiterite (SnO 2 ), present within the glaze as opacifier was explored on lead antimonate yellow glaze mock-ups fired at different temperatures.

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We report a new structure determination of the Sr1.2872NiO3 incommensurate composite hexagonal perovskite compound. Three different refinement strategies are presented:  (i) a 3D supercell approximation with a nonharmonic development of the atomic displacement factor, (ii) an original (3+1)D incommensurate composite description with the use of crenel functions, and (iii) a (3+1)D commensurate composite model. The three strategies are discussed and compared to previous refinements carried out for the hexagonal perovskites in a classical way or with the superspace group formalism. Out of the three methods, the incommensurate composite approach gives slightly better results with a final global R value of 2.89% for 635 independent reflections (at a I/σ(I) > 2 level) and only 60 parameters (R3̄m(00γ)0s superspace group; a = 9.5177(7) Å, c = 2.5739(2) Å, q = 0.64359(4)c*, V = 201.93(4) Å3, and Z = 3). The use of crenel functions notably improves previously reported results. New structural features are evidenced for Sr1.2872NiO3:  (i) an incommensurate character, (ii) a splitting of the trigonal prismatic nickel atoms over 5 positions, (iii) a definite stoichiometry which induces a perfect charge balance, and (iv) a nonharmonic behavior of some Sr atoms. Those characteristics seem general to most hexagonal perovskite compounds and essential for correctly interpreting their interesting magnetic properties. Finally, a new generic formulation is proposed, which explains the various stoichiometries observed and suggests a new compound possibility.