Main bond distances ( \AA), selected angles ( { }^{\circ}), and \Phi\left(\Phi^{\prime}\right) and \Psi\left(\Psi^{\prime}\right) tilt angles, for \mathrm{Sr}_{2} \mathrm{Ni}_{1-x} \mathrm{Mg}_{x} \mathrm{TeO}_{6}(x=0.0,0.1,0.2,0.3 and 0.5) at room temperature. The values were obtained refining the mode breaking the symmetry from the cubic F m \overline{3} m to the monoclinic I 2 / m.
| \mathrm{Sr}_{2} \mathrm{NiTeO}_{6} | \mathrm{Sr}_{2} \mathrm{Ni}_{0.9} \mathrm{Mg}_{0.1} \mathrm{TeO}_{6} | \mathrm{Sr}_{2} \mathrm{Ni}_{0.8} \mathrm{Mg}_{0.2} \mathrm{TeO}_{6} | \mathrm{Sr}_{2} \mathrm{Ni}_{0.7} \mathrm{Mg}_{0.3} \mathrm{TeO}_{6} | \mathrm{Sr}_{2} \mathrm{Ni}_{0.5} \mathrm{Mg}_{0.5} \mathrm{TeO}_{6} | |
|---|---|---|---|---|---|
| \mathrm{Ni} / \mathrm{MgO}_{6} octahedra | |||||
| \mathrm{Ni} / \mathrm{Mg}-\mathrm{O} 1 | 2.011(1) \times 4 | 2.010(1) \times 4 | 2.009(1) \times 4 | 2.008(1) \times 4 | 2.007(1) \times 4 |
| \mathrm{Ni} / \mathrm{Mg}-\mathrm{O} 2 | 2.012(2) \times 2 | 2.009(1) \times 2 | 2.008(2) \times 2 | 2.009(2) \times 2 | 2.008(2) \times 2 |
| Average distance | 2.011(6) | 2.010(6) | 2.009(6) | 2.008(6) | 2.007(1) |
| Predicted distance | 2.0605 | 2.0605 | 2.0605 | 2.0605 | 2.0605 |
| \mathrm{TeO}_{6} octahedra | |||||
| Te-O1 | 1.966(1) \times 4 | 1.964(1) \times 4 | 1.964(1) \times 4 | 1.963(1) \times 4 | 1.962(1) \times 4 |
| Te-O2 | 1.968(2) \times 2 | 1.965(1) \times 2 | 1.965(2) \times 2 | 1.964(2) \times 2 | 1.963(2) \times 2 |
| Average distance | 1.967(6) | 1.964(6) | 1.964(1) | 1.964(6) | 1.962(6) |
| Predicted distance | 1.9170 | 1.9170 | 1.9170 | 1.9170 | 1.9170 |
| ∠O1-Ni/Mg-O2 | 89.9(2) | 89.8(2) | 89.9(2) | 90.1(1) | 90.1(2) |
| \angle \mathrm{O} 2-\mathrm{Ni} / \mathrm{Mg}-\mathrm{O} 2 | 89.1(1) | 89.0(7) | 90.0(7) | 90.1(7) | 90.2(7) |
| \angle \mathrm{O} 1-\mathrm{Te}-\mathrm{O} 2 | 89.8(4) | 89.9(4) | 89.9(4) | 89.9(4) | 89.9(4) |
| \angle \mathrm{O} 2-\mathrm{Te}-\mathrm{O} 2 | 89.1(4) | 90.1(4) | 90.1(4) | 90.1(4) | 90.1(4) |
| \angle \mathrm{Ni} / \mathrm{Mg}-\mathrm{O} 1-\mathrm{Te} | 164.5(1) | 164.7(5) | 164.5(1) | 163.7(2) | 163.5(2) |
| \angle \mathrm{Ni} / \mathrm{Mg}-\mathrm{O} 2-\mathrm{Te} | 169.1(1) | 169.0(8) | 169.1(2) | 168.6(3) | 168.2(4) |
| \Phi\left(\mathrm{TeO}_{6}\right) / \Phi^{\prime}\left(\mathrm{Ni} / \mathrm{MgO}_{6}\right) | 8.852(2) | 7.879(1) | 7.551(2) | 7.547(2) | 7.345(2) |
| \Psi\left(\mathrm{TeO}_{6}\right) / \Psi^{\prime}\left(\mathrm{Ni} / \mathrm{MgO}_{6}\right) | 8.656(2) | 7.704(1) | 7.385(2) | 7.379(2) | 7.181(2) |