Magnetic behavior of manganese chloride on Kagome and honeycomb lattices

The magnetic properties of transparent pink Na2Mn3Cl8 and NaMnCl3 are presented. For both phases, the effective magnetic moments are large, while the Curie-Weiss thetas are below 10 K. The compounds crystallize in the Trigonal R-3m and R-3 space groups, respectively. A Kagome plane of Mn2+ octahedrally coordinated to Cl− is found in Na2Mn3Cl8 and the material has no apparent magnetic ordering above 1.8 K, while the octahedrally coordinated, honeycomb network of Mn2+ in NaMnCl3 orders antiferromagnetically at 6.3 ± 0.2 K. The heat capacity of NaMnCl3 has one transition, consistent with the susceptibility; while Na2Mn3Cl8 exhibits a more complex heat capacity with two peaks, at 0.7 K and 1.2 K. A third, broad peak near 6.2 K in the heat capacity of Na2Mn3Cl8 is problematic but may be due to the intergrowth of domains of NaMnCl3.