Table 2 Refined structural parameters of Mg-rich Mg–Fe–O under an assumption that the sample is composed from (a) the Mg-rich spinel oxide (S. G.: Fd-3 m) and (b) MgO with a rocksalt structure (S. G.: Fm-3 m).

From: Positive-electrode properties and crystal structures of Mg-rich transition metal oxides for magnesium rechargeable batteries

a

Atom

Site

x

y

z

B/Å2

Site occupancy

Mg1

8a

0

0

0

0.25(1)

0.405

Fe1

8a

 = x(Mg1)

 = y(Mg1)

 = z(Mg1)

 = B(Mg1)

0.577

Mg2

16d

5/8

5/8

5/8

0.33(1)

0.506(2)

Fe2

16d

 = x(Mg2)

 = y(Mg2)

 = z(Mg2)

 = B(Mg2)

0.495(2)

Mg3

16c

1/8

1/8

1/8

0.3(2)

0.118(4)

O1

32e

0.3804(1)

 = x(O1)

 = x(O1)

0.56(2)

1

b

Atom

Site

x

y

z

B/Å2

Site occupancy

Mg4

4a

0

0

0

0.21(3)

1

O2

4b

1/2

1/2

1/2

0.35(4)

1

  1. The spinel phase can be expressed as Mg1.651Fe1.566O4, and the weight ratio is 69.6%. In this model, the 16c site is occupied partially by the excess Mg.
  2. Lattice parameters: a = 8.39483(8) Å (spinel) and a = 4.2127(1) Å (rocksalt).
  3. R factors are Rwp = 5.69%, Rp = 4.44%, and Re = 2.22%.
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