Double Double Cation Order in the High-Pressure Perovskites MnRMnSbO6 - Solana-Madruga, Elena; Arevalo-Lopez, Angel M.; Dos Santos-Garcia, Antonio J.; Urones-Garrote, Esteban; Avila-Brande, David; Saez-Puche, Regino; Attfield, J. Paul; (Angewandte Chemie (International Ed. Print), 2016)