| Abstract
| - Reaction of the n = 2 Ruddlesden−Popper phase YSr2Mn2O7 with NaH at 225 °C yields thetopotactically reduced phase YSr2Mn2O5.43(3) (a = 3.62043(4) Å, c = 22.3570(3) Å). Combination ofthis reduced phase with the stoichiometric starting material at 400 °C yields intermediate phases: YSr2Mn2O6.54(3) (a = 3.80900(7) Å, c = 20.2691(5) Å) and YSr2Mn2O5.96(3) (a = 3.81071(7) Å, c = 20.5238(4) Å). The variation in the anion vacancy distribution of these reduced phases as a function ofstoichiometry is discussed in relation to the coordination polyhedra of the metal cations. Temperature-dependent magnetization data indicate strong antiferromagnetic coupling interactions in all samples. Long-range magnetic order is suppressed by structural or charge disorder in all samples except YSr2Mn2O5.5,which adopts a G-type antiferromagnetic ordering scheme with an ordered moment of 4.61(5)μB permanganese, consistent with S = 5/2 Mn(II).
- Topotactic reduction of YSr2Mn2O7 allows the preparation of anion-deficient YSr2Mn2O7-x (0 < x<1.5) phases. Magnetic order is suppressed by structural and charge disorder in all but the most reduced phase YSr2Mn2O5.5.
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