Magnetic properties D 9000Preparation, Crystal Structure and Magnetic Properties of Ruddlesden-Popper Phases La1.2Sr1.8Mn2-xRuxO7 (x: 0, 0.05, 0.1, 0.2, 0.5). -The title compounds are synthesized by solid state reactions of appropriate amounts of La2O3, SrCO3, Mn2O3, and RuO2 in several heating cycles. As revealed by powder XRD they crystallize in the tetragonal space group I4/mmm with Z = 2. Magnetization and ac susceptibility measurements indicate an increase of the ferromagnetic Curie temperature with increasing Ru content from 121 K for x = 0.05 to 160 K for x = 0.5. -(SCHUEPP*, B.; DOERR, K.; RUCK, K.; NENKOV, K.; MUELLER, K.-H.; KRABBES, G.; Solid State Sci. 7 (2005) 1, 17-23; Inst.

Preparation of Layered Manganites: Oxygen Content as a VariableParameter of the Bilayer Compound.-The formation temperature of bilayer compounds of general formula La 2−2x Sr 1+2x Mn 2 O 7 is found to increase from 1350 to 1500 • C with decreasing Sr content for a substitution level in the range 0.7 ≤ x ≤ 0.25. Samples with different oxygen content of the ferromagnetically ordered parent compound La 1.2 Sr 1.8 Mn 2 O 7 are prepared at an oxygen partial pressure of 10 −10 Pa. For La 1.2 Sr 1.8 Mn 2 O 7−δ the tetragonal phase is preserved up to δ = 0.27 and changes to orthorhombic symmetry at higher δ values. The Curie temp. as well as the metal-insulator transition temp. decrease with increasing δ. -(RUCK, K.; SGRAJA, M.; KRABBES, G.; DOERR, K.; MUELLER, K.-H.; KHRISTOV, M.; J. Alloys Compd. 306 (2000) 1-2, 151-157; Inst. Festkoerper-Werkstofforsch.,

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