Table 1 Lowest-energy structures of A2MSiO4 in three different types obtained in current study.

From: Exploration of tetrahedral structures in silicate cathodes using a motif-network scheme

 

Li2MnSiO4

Li2FeSiO4

Li2CoSiO4

Na2MnSiO4

Na2FeSiO4

Na2CoSiO4

r(A)/r(M)

1.04

1.07

1.10

1.18

1.22

1.25

Structures with 1D M-Si-O framework

E

−54.891

−53.174

−51.070

−52.212

−50.497

−48.398

Space group

Cmcm (#63)

Cmcm (#63)

Cmcm (#63)

Cmcm (#63)

Cmcm (#63)

Cmcm (#63)

Lattice

a = 7.40, b = 7.56, c = 6.42

a = 7.47, b = 7.49, c = 6.30

a = 7.54, b = 7.52, c = 6.18

a = 8.89, b = 8.09, c = 6.39

a = 8.95, b = 7.96, c = 6.31

a = 8.96, b = 7.98, c = 6.22

V

89.80

88.12

87.61

114.89

112.38

111.18

plot

Fig. 5a

Fig. 5a

Fig. 5a

Fig. 5a

Fig. 5a

Fig. 5a

Structures with 2D M-Si-O framework

E

−55.061

−53.290

−51.296

−52.484

−50.746

−48.754

Space group

Pmna (#62)

Pmna (#62)

Pmn21 (#31)

P-1 (#2)

P-1 (#2)

P-1 (#2)

Lattice

a = 10.91, b = 6.38, c = 5.10

a = 10.80, b = 6.33, c = 5.05

a = 6.20, b = 5.46, c = 5.00

a = 5.61, b = 6.11, c = 6.27, α = 77.64° β = 89.96° γ = 89.87°

a = 5.73, b = 6.05, c = 6.12, α = 75.43° β = 87.99° γ = 89.17°

a = 5.53, b = 6.01, c = 6.20, α = 103.40° β = 90.27° γ = 90.25°

V

88.66

86.33

84.60

105.00

102.76

100.36

plot

Fig. 4a

Fig. 4a

Fig. 4d

Figure 7
figure 7

The lowest-energy structure with 2D M-Si-O framework for the Na systems with space group P-1 (#2).

(a–c) Views of the P-1 structure along different lattice vectores. (d) Na-O pyramids extracted from this structure, where every Na atom bonds with 5 O atoms.

Full size image

Fig. 7

Fig. 7

Structures with 3D M-Si-O framework

E

−55.012

−53.263

−51.330

−52.662

−50.879

−48.934

Space group

Pna21 (#33)

P212121 (#19)

Pn (#7)

Pn (#7)

Pn (#7)

Pn (#7)

Lattice

a = 11.05, b = 6.39, c = 5.07

a = 11.02, b = 6.29, c = 5.07

a = 5.01, b = 16.20, c = 8.07, β = 128.33°

a = 5.42, b = 5.72, c = 8.87, β = 127.39°

a = 5.41, b = 5.71, c = 8.74, β = 127.67°

a = 5.34, b = 5.58, c = 8.82, β = 127.06°

V

89.48

87.72

85.59

109.33

106.71

104.78

plot

Fig. 3d

Fig. 3e

Fig. 3f

Fig. 3a

Fig. 3a

Fig. 3a

  1. r represents the atomic radius; E is the total energy in eV/f.u.; V is the volume of the structure in Å3/f.u.; a, b, and c are the lattice parameters in Å. The corresponding figure of each structure is listed in the “plot” row.
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