Crystal growth and magnetic properties of the double perovskites R2MnNiO6 (R=Pr, Sm and Ho) by a hydrothermal route

Double-perovskite oxides R2MnNiO6 (R=Pr, Sm, and Ho) were synthesized under mild hydrothermal conditions. Crystal growths of the samples were sensitive to the alkalinity, the reaction temperature and the time. The X-ray diffraction data show that all the compounds crystallize in the monoclinic structure of space group P21/n. The purity and composition of the crystals are detected by ICP, SEM and EDX analysis. The magnetic studies for all the compounds indicated the dominance of ferromagnetic contribution and revealed a trivalent valence of both Mn and Ni with partial disorder. The TC temperature of the R2NiMnO6 series is depended on the radius of R3+ atoms, which is consistent with the previous reported.

► R2MnNiO6 (R=Pr, Sm, and Ho) have been synthesized under mild hydrothermal conditions.
► R2MnNiO6 (R=Pr, Sm, and Ho) crystallize in P21/n.
► Synthesis of R2MnNiO6 is sensitive to the alkalinity, the reaction temperature and the time.
► Single crystal of Ho2MnNiO6 has been obtained.
► The value of TC of the R2NiMnO6 series decrease with the decrease of the radius of R3+ ions.