Neutron total scattering and reverse Monte Carlo study of cation ordering in Ca_xSr_1-xTiO₃

We use neutron total scattering measurements with reverse Monte Carlo analysis methods incorporating an atom-swapping algorithm to identify the short-range Ca/Sr cation ordering within the Ca_xSr _1-xTiO₃ solid solution (compositions x ≤ 0.2,0.5,0.8). Our results show that nearest-neighbour pairs have a strong tendency for unlike Ca/Sr first-neighbour coordination in the x ≤ 0.2 and 0.5 cases. In the x ≤ 0.5 case the Ca/Sr ordering results in a structure with space group P 2₁nm. In contrast, there is much less short-range cation ordering in the x ≤ 0.8 case.