Complex magnetic behaviour of Sr2CoNb1−xTixO6 (0 ≤ x ≤ 0.5) as a result of a flexible microstructureElectronic supplementary information (ESI) available: Fig. SI 1. Experimental and calculated XRD patterns for Sr2CoNb3O6. Fig. SI 2. Experimental and calculated XRD patterns for Sr2CoNb0.9Ti0.1O6. Fig. SI 3. Experimental and calculated XRD patterns for Sr2CoNb0.8Ti0.2O6. Fig. SI 4. Experimental and calculated XRD patterns for Sr2CoNb0.7Ti0.3O6. Fig. SI 5. Experimental and calculated XRD patterns f

We report the rich magnetic behaviour of Sr 2 CoNb 1− x Ti x O 6 (0 ≤ x ≤ 0.5) oxides as a result of their complex microstructure. Although these oxides show an average simple-cubic perovskite structure, they present a flexible microstructure due to short-range ordering between Co/Ti and Nb cations in the perovskite B-sites. The microstructure consists of double-cubic perovskite domains grown in a simple-cubic perovskite matrix. The size and number of the double-cubic perovskite domains decrease as the Ti content increases. As a result of aliovalent substitution of Nb 5+ by Ti 4+ in the parent Sr 2 CoNbO 6 mixed-valence Co 3+ /Co 4+ oxides are obtained. A spin glass-like state has been observed at low temperatures for all the series, with freezing temperatures increasing with the Ti-content in the range 22 to 33 K. Furthermore, the x = 0.3 and x = 0.5 samples show non-interacting superparamagnetic particle-like dynamics associated with relatively high amounts of Co 4+ , with "blocking temperatures" of 13 and ∼16 K, respectively. The complex magnetic behaviour of the title oxides seems to be connected with the clustering of magnetic Co 3+ and the distribution of Co 4+ as a result of the microstructure. We report the rich magnetic behaviour of Sr 2 CoNb 1− x Ti x O 6 (0 ≤ x ≤ 0.5) oxides as a result of their complex microstructure.