The disordered cubic structure of Ca7Co3Ga5O18

✍ Scribed by J. Grins; S.Ya. Istomin; G. Svensson; J.P. Attfield; E.V. Antipov

• Book ID: 104029254
• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 556 KB
• Volume: 178
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2005.04.029

✦ Synopsis

The new mixed oxide having composition close to Ca 7 Co 3 Ga 5 O 18 was synthesized from CaCO 3 , Co 3 O 4 and Ga 2 O 3 at 1150 1C in air and studied by neutron and synchrotron X-ray powder diffraction, selected-area electron diffraction and high-resolution electron microscopy. The structure was refined, using time-of-flight (TOF) neutron powder diffraction data, in space group F432, with a ¼ 15:0487ð4Þ ( A and Z ¼ 8, to R F ¼ 0:7%. It is considerably disordered, with four different tetrahedral sites randomly occupied by Co and Ga atoms at a ratio of 1:2. The tetrahedra form a disordered (Co 1/3 Ga 2/3 )O 2 3D-framework inside which isolated CoO 6 octahedra, surrounded by 8 Ca atoms, are located. The structure is related to the ordered structure of Ca 14 Al 10 Zn 6 O 35 . Electron diffraction patterns confirmed the symmetry and unit cell and revealed no diffuse scattering. High-resolution electron microscopy images showed the absence of extended structural defects.