Selected room-temperature interatomic distances/pm and angles/ { }^{\circ} for \mathrm{Sr}_{2} \mathrm{Co}_{1-x} \mathrm{Fe}_{x} \mathrm{TeO}_{6}(x=0,0.25,0.5,0.75, and 1)
| Composition | x=0 | x=0.25 | x=0.25 | x=0.25 | x=1 |
|---|---|---|---|---|---|
| 2d octahedra | |||||
| ( \mathrm{Co} / \mathrm{Fe} / \square )-O1 | 213.6(3) | 206.0(3) | 205(2) | 205.5(3) | 203(1) |
| ( \mathrm{Co} / \mathrm{Fe} / \square )-O2 | 214.5(4) | 207.2(2) | 204(3) | 203.4(2) | 201.1(1) |
| \mathrm{Co}-\mathrm{O} 3 | 207.5(3) | - | - | - | - |
| Average distance/pm | 208.7(1) | 207(1) | 205(1) | 203.6(1) | 201.7(1) |
| Predicted distance/pm | 214(1) | 208(1) | 207(1) | 207(1) | 204(1) |
| 2a octahedra | |||||
| ( \mathrm{Te} / \mathrm{Fe} )-O1 | 195.5(4) | 196.7(3) | 195.3(2) | 195.9(3) | 197(1) |
| ( \mathrm{Te} / \mathrm{Fe} )-O2 | 197.4(3) | 193.7(2) | 196(3) | 197(2) | 196.8(1) |
| Te-O3 | 192.5(4) | - | - | - | - |
| Average distance/pm | 194.9(1) | 195.2(1) | 195.6(1) | 196.4(1) | 197.1(1) |
| Predicted distance/pm | 196(1) | 196(1) | 196(1) | 196(1) | 196(1) |
| \mathrm{O} 1-(\mathrm{Co} / \mathrm{Fe} / \square)^{2 d}-\mathrm{O} 2 | 90.60(1) | 92.50(2) | 93(3) | 93(2) | 91.0(2) |
| \mathrm{O} 2-(\mathrm{Co} / \mathrm{Fe} / \square)^{2 d}-\mathrm{O} 2 | 90.60(1) | 92(3) | 92(2) | 91(14) | 93.70(2) |
| \mathrm{O} 2-(\mathrm{Co} / \mathrm{Fe} / \square)^{2 d}-\mathrm{O} 3 | 91.20(1) | - | - | - | - |
| \mathrm{O} 1-(\mathrm{Te} / \mathrm{Fe})^{2 a}-\mathrm{O} 2 | 90.50(2) | 92.3(2) | 92(2) | 92(2) | 90.90(1) |
| \mathrm{O} 2-(\mathrm{Te} / \mathrm{Fe})^{2 a}-\mathrm{O} 2 | 90.80(2) | 92(3) | 91(2) | 91(1) | 92.0(1) |
| \mathrm{O} 2-(\mathrm{Fe} / \mathrm{Te})^{2 a}-\mathrm{O} 3 | 90.50(2) | - | - | - | - |
| (\mathrm{Co} / \mathrm{Fe} 1 / \square)^{2 d}-\mathrm{O} 1-(\mathrm{Te} / \mathrm{Fe} 2)^{2 a} | 163.7(3) | 160.74(3) | 155(3) | 167.0(3) | 167.2(3) |
| (\mathrm{Co} / \mathrm{Fe} 1 / \square)^{2 d}-\mathrm{O} 2-(\mathrm{Te} / \mathrm{Fe} 2)^{2 a} | 165.6(3) | 171.04(3) | 174.4(3) | 167.4(3) | 172.0(2) |
| (\mathrm{Co} / \mathrm{Fe} 1 / \square)^{2 d}-\mathrm{O} 3-(\mathrm{Te} / \mathrm{Fe} 2)^{2 a} | 168.1(3) | - | - | - | - |
| \mathrm{SrO}_{12} icosahedron | |||||
| \mathrm{Sr}-\mathrm{O} 1 | 2.67(3) | 2.82(3) | 2.67(3) | ||
| Sr-O2 (\times 2) | 2.534(3) | 2.56(3) | 2.56(3) | ||
| \mathrm{Sr}-\mathrm{O} 2(\times 2) | 2.643(2) | 2.67(3) | 2.74(3) |