Synthesis, structural characteristics and dielectric properties of a new K2NiF4-type phase Sr2Mn0.5Ti0.5O4

• The new complex oxide Sr2Mn0,5Ti0,5O4 was prepared.
• The structures of the compound were analyzed by Rietveld refinement.
• Distortions of SrO9 and (Mn,Ti)O6 polyhedra are not strong.
• Dielectric properties are determined by regular structure and lack of charge ordering.
• Permittivity increase under heat is associated with processes at the grain boundaries.

A new K2NiF4-type phase Sr2Mn0,5Ti0,5O4 have been synthesized by a sol–gel procedure and characterized by X-ray powder diffraction, thermogravimetric analysis and scanning electron microscopy. There are no oxide ion vacancies in these materials; oxidation states of manganese and titanium were estimated as +4. Rietveld profile analysis shows that the phase crystallizes with tetragonal unit cell in the space group I4/mmm. Substitution of Ti4+ for Mn4+ does not affect the distortion of coordination polyhedra (Mn,Ti)O6 and SrO9. The dielectric properties of the ceramic samples are caused by structural and charge characteristics, regular coordination polyhedra SrО9 and lack of charge ordering, which can lead to significant permittivity. Increase of the dielectric constant at temperatures above 453 K is caused mainly by the grain boundary processes explained in terms of the Maxwell–Wagner polarization model.

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