“…18 The Rietveld fit to the data clearly indicates an excellent fit to the monoclinic, C2/m, model expected for Ca 2 Mn 3 O 8 . 18,30,31 Additional phases of Pb (Fm% 3m) from the pressure calibrant and, ZrO 2 (P4 2 /nmc) and Al 2 O 3 (R% 3c) from the anvil were also refined.…”