Crystal growth features and properties of layered rare earth and barium cobaltates

✍ Scribed by G. L. Bychkov; S. V. Shiryaev; A. G. Soldatov; A. S. Shestak; S. N. Barilo; D. V. Sheptyakov; K. Conder; E. Pomjakushina; A. Podlesnyak; A. Furrer; R. Bruetsch

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 151 KB
• Volume: 40
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/crat.200410356

✦ Synopsis

Abstract

High quality single crystals of LnBaCo~2~O~5+δ~ (0 < δ < 1) (Ln = Pr, Eu, Gd, Tb, Dy) with rectangular shape and average dimensions 5 mm × 5 mm × 1 mm were grown for the first time from overstoichiometric flux melt. The data on the primary crystallization field of most cobaltate phases, which appear in parts of corresponding Gibbs triangles in the range 1373 – 1523 K are discussed. Bulk single crystals of new phases HoBaCo~4~O~7~ up to 300 mm^3^, YBaCo~4~O~7~ and TbBaCo~4~O~7~ up to 10 mm^3^ in volume were grown first. A solution of these compounds structure has been found in the space group P6~3~mc. For the Ln = Pr, Gd, Sm, Tb, Dy, Ho based systems under the liquidus line there are several other new cobaltate phases of both perovskite, and hexagonal crystal structure. Stability of the double perovskite phase and temperature of the antiferromagnetic – ferromagnetic phase transition in relation to the radius of rare earth ions are compared. The data on the exact analysis of chemical composition, including EDX and iodometric titration, as well as results on magnetic susceptibility of EuBaCo~1‐x~Al~x~O~5+δ~ (0 < x < 0.3) are discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)