Phase coexistence in annealed CaMn7O12

✍ Scribed by Radosław Przeniosło; Wouter van Beek; Izabela Sosnowska

• Book ID: 104166125
• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 146 KB
• Volume: 126
• Category: Article
• ISSN: 0038-1098
• DOI: 10.1016/s0038-1098(03)00257-6

✦ Synopsis

The structural phase transition in annealed CaMn 7 O 12 has been investigated by using high resolution synchrotron radiation powder diffraction. There is a phase coexistence phenomenon: two different crystallographic phases coexist in the material between 410 and 458 K. The first one is trigonal and it has a charge ordering (CO) of the Mn 3þ and Mn 4þ ions, while the second one is cubic and charge delocalized (CD). The volume fraction of the CD phase increases with temperature from 22% at 418 K up to 100% at 468 K. Both phases have domains of at least 150 nm at each temperature. The annealing of CaMn 7 O 12 relaxed a part of the strains in the lattice, but did not influence the phase coexistence phenomenon.