Hexagonal Ba-ferrite: a good model for the crystal structure of a new high-pressure phase CaAl4Si2O11?

Details Hexagonal Ba-ferrite: a good model for the crystal structure of a new high-pressure phase CaAl4Si2O11? Hexagonal Ba-ferrite: a good model for the crystal structure of a new high-pressure phase CaAl4Si2O11?

Jul 1997

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997pepi..102..223g&link_type=abstract

Physics of the Earth and Planetary Interiors, v. 102, p. 223-229.

Physics

5

Scientific paper

A new calcium aluminosilicate phase of composition CaAl4Si2O11 has been encountered amongst the transformation products of CaAl2Si2O8 (anorthite composition) at 14 GPa (Gautron et al., 1996). X-ray diffraction (XRD) confirms that its crystal structure is essentially the same as that of a new complex Ca-Al-silicate (abbreviated CAS phase) first reported by Irifune et al. (1994). The crystal structure of the CAS phase has been investigated by transmission electron microscopy (TEM). It has a hexagonal unit cell with lattice parameters a = 5.4 Å and c = 12.7 Å, and its space group is either P63mc, P62c or P63/mmc. It is proposed that this CAS phase has a six-layer, close-packed structure so that Z = 2 and density is 3.94 g cm-3, reasonable for a phase stable at transition-zone pressures. The most plausible model for the structure of this phase arises from published refinements of hexagonal Ba-ferrites. This postulated P63/mmc structure consists of octahedral layers, 3/(4) occupied, separated by 12-coordinate Ca atoms, and by Al and Si in face-shared octahedra and in complex trigonal bipyramidal polyhedra, i.e. some Si would be five-fold coordinated. Observed TEM and XRD data are compared with calculated reflection intensities for this CAS model.

Affiliated with

Also associated with

No associations

Rating

Hexagonal Ba-ferrite: a good model for the crystal structure of a new high-pressure phase CaAl4Si2O11? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Hexagonal Ba-ferrite: a good model for the crystal structure of a new high-pressure phase CaAl4Si2O11?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hexagonal Ba-ferrite: a good model for the crystal structure of a new high-pressure phase CaAl4Si2O11? will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1416807