Nitrogen ordering in ζ-manganese nitrides with hcp arrangement of Mn – MnNy with 0.39 < y < 0.48 – determined by neutron diffraction

High temperature axial ratios c/a in hcp-based ε-type interstitial nitrides MN with M=Mn, Fe, Ni

“…Two hcp-based manganese nitrides with ε-type N ordering (Table 1; prepared from manganese and nitrogen at 1023 K), for which high temperature neutron diffraction data and X-ray diffraction data obtained at ambient temperature [8,18,19] exist, will be considered here, MnN 0.388 and MnN 0.421 . These nitrides show apparently continuous order-disorder phase transitions with transition temperatures of 550-560 K (MnN 0.388 ) and 575 K (MnN 0.421 ) giving a disordered (with respect to N) high temperature phase.…”

“…Averaged linear thermal expansion coefficient in [20], Table 2 a It should be noted that for the hcp-based iron and manganese nitrides the unit cell parameters increase largely linearly with increasing N content at constant temperature [7,8,[11][12][13][14].…”

“…In hcp-based interstitial phases these contacts occur only parallel to (0 0 1) and can be accommodated by an expansion of the structure in that direction. This becomes especially obvious for orthorhombic superstructures, for which the structure expands preferentially in those directions parallel to (0 0 1) in which all the edge-sharing contacts occur [7][8][9]. The edge-sharing contacts need not occur for the composition M 3 X if, for example, the perfect ε-Fe 3 N superstructure is formed [10], but edge-sharing contacts must be present for y-values above 1/3.…”

“…Recently, a series of high temperature neutron powder diffraction measurements were reported on hcp-based iron [10,16], manganese [8,[17][18][19] and nickel nitride Ni 3 N [20], mainly focussing on order-disorder phenomena with respect to the N arrangement and on the occurrence of magnetically ordered phases, whereas the temperature de- Table 1 Unit cell parameters a of the nitride samples taken at ambient temperatures and plotted in Figs. 1 and 2…”

Solvothermal synthesis and electrochemical charge storage assessment of Mn3N2

“…The defect NiAs-type -Mn2N phase has a range of nitrogen contents typically from MnN0.42 2 to Mn2N1.08. 3 with nitrogen occupancy varying according to the composition.…”