Bond lengths ( \AA), octahedra tilt angles ( { }^{\circ}), and selected angles ( { }^{\circ}) for \mathrm{BaLn}_{2} \mathrm{CuTi}_{2} \mathrm{O}_{9} ( \mathrm{Ln}=\mathrm{La}, \mathrm{Pr}, \mathrm{Nd}) at room temperature calculated from XRPD pattern with I4/mcm space group.
| \mathrm{BaLa}_{2} \mathrm{CuTi}_{2} \mathrm{O}_{9} | \mathrm{BaPr}_{2} \mathrm{CuTi}_{2} \mathrm{O}_{9} | \mathrm{BaNd}_{2} \mathrm{CuTi}_{2} \mathrm{O}_{9} | |
|---|---|---|---|
| \mathrm{Ba} / \operatorname{LnO}_{12} polyhedra | |||
| \mathrm{Ba} / L n-O1 (\times 4) | 2.802(1) | 2.792(1) | 2.789(1) |
| \mathrm{Ba} / \operatorname{Ln}-O1 (\times 4) | 2.961(7) | 3.004(8) | 3.024(9) |
| \mathrm{Ba} / \operatorname{Ln}-O1(×4) | 2.649(6) | 2.592(7) | 2.568(7) |
| <\mathrm{Ba} / L n-\mathrm{O}> | 2.804(7) | 2.796(8) | 2.794(9) |
| Tilt angle \psi_{[001] \mathrm{p}} | 6.4(2) | 8.4(2) | 9.3(2) |
| \mathrm{Cu} / \mathrm{TiO}_{6} octahedra | |||
| \mathrm{Cu} / \mathrm{Ti}-\mathrm{O} 1_{\mathrm{ax}}(\times 2) | 1.98(1) | 1.97(1) | 1.97(1) |
| \mathrm{Cu} / \mathrm{Ti}-\mathrm{O} 2_{\text {eq }}(\times 4) | 2.00(1) | 2.00(1) | 2.00(1) |
| <\mathrm{Cu} / \mathrm{Ti}-\mathrm{O}> | 1.99(1) | 1.99(1) | 1.99(1) |
| \angle \mathrm{O} 2_{\text {eq }}-\mathrm{Cu} / \mathrm{Ti}-\mathrm{O} 2^{\prime}{ }_{\text {eq }} | 90.0(2) | 90.0(2) | 90.0(2) |
| \angle \mathrm{Cu} / \mathrm{Ti}-\mathrm{O}_{2}{ }_{\mathrm{eq}}-\mathrm{Cu} / \mathrm{Ti} | 167.2(3) | 163.2(3) | 161.4(3) |