[Structure and Bonding] Localized to Itinerant Electronic Transition in Perovskite Oxides Volume 98 || General Considerations

✍ Scribed by Goodenough, John B.

• Book ID: 111690821
• Publisher: Springer Berlin Heidelberg
• Year: 2001
• Tongue: German
• Weight: 180 KB
• Edition: 2001
• Category: Article
• ISBN: 3540675221
• DOI: 10.1007/3-540-45503-5_1

✦ Synopsis

Interest In The Transition Metal Oxides With Perovskite Related Structures Goes Back To The 1950s When The Sodium Tungsten Bronzes Naxwo3 Were Shown To Be Metallic [1 ], The System Lal_xsr Mno3 Was Found To Contain A Ferromagnetic Conductive Phase [2], And La0.ssr0.scoo3 Was Reported To Be A Ferromagnetic Metal, But With A Peculiar Magnetization Of 1.5 #a/co Atom [3]. Stoichiometric Oxide Perovskites Have The Generic Formula Amo3 In Which The A Site Is At The Center Of A Simple Cubic Array Of M Sites; The Oxide Ions Form (180 ° 4)) M O M Bridges To Give An Mo3 Array Of Corner Shared Mo6/2 Octahedra And The Larger A Cations Have Twelvefold Oxygen Coordination. Mismatch Between The A O And M O Equilibrium Bond Lengths Introduces Internal Stresses. A Compressive Stress On The Mo3 Array Is Accommodated By A Lowering Of The M O M Bond Angle From 180 ° To (180 ° 4)); A Tensile Stress On The M O M Bonds Is Accommodated By The Formation Of Hexagonal Polytypes [4].