posted on 2007-02-20, 00:00authored byJosephine J. Adkin, Michael A. Hayward
The synthesis and structural characterization of 15R-, 8H-, 6H‘-, and 10H-BaMnO3-x and 9R-Ba0.875Sr0.125MnO3 is described. Neutron powder diffraction data reveal a strong preference for the location of
anion vacancies within the face-shared hexagonal layers of these phases. At high anion vacancy
concentrations, Mn2O9-x dimer units become prevalent. Magnetic characterization indicates antiferromagnetic order in all phases. Ordering temperatures are in the range 250 K < T < 270 K and show a
dependence on the fraction of cubic layers present in the stacking sequence.