Structural and magnetic properties of Co2Al4Si5O18 and Mn2Al4Si5O18 cordierite |
| |
| Authors: | K Knorr M Meschke B Winkler |
| |
| Institution: | Mineralogisch-Petrographisches Institut, Christian-Albrechts Universit?t zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany, DE
Hahn-Meitner-Institut Berlin, Dept. NE, Glienicker Str. 100, D-14109 Berlin, Germany e-mail: knorr@min.uni-kiel.de, DE
|
| |
| Abstract: | The crystal structures, lattice dynamics and magnetic properties of synthetic Co-cordierite, Co2Al4Si5O18, and Mn-cordierite, Mn2Al4Si5O18 have been studied by neutron powder diffraction, infrared spectroscopy and magnetisation measurements. Due to different synthesis
conditions, the Co-cordierite used here crystallised in the hexagonal α-cordierite structure with a disordered Si/Al distribution
in the framework, while for the Mn-cordierite the orthorhombic β-structure has been determined. The experimentally determined
paramagnetic moments,
exp
(Mn) = 5.47(6)
B
and
exp
(Co) = 3.88(4)
B
, are in good agreement with theoretical predictions for octahedrally coordinated Mn2+ and Co2+, respectively. In both compounds there is no magnetic long-range order down to at least 1.5 K. However, the onset of an anti-ferromagnetic
short-range correlation of magnetic moments along 001] has been observed for Mn-cordierite by magnetisation and neutron diffraction
measurements. This short-range magnetic correlation becomes evident from diffuse scattering observed at 2 K. The diffuse scattering
has been interpreted in terms of a Blech-Averbach function.
Received: 30 June 1998 / Revised, accepted: 3 March 1999 |
| |
| Keywords: | Cordierite Order/disorder Neutron powder diffraction Magnetic properties |
| 本文献已被 SpringerLink 等数据库收录！ |
|
