Structure and colossal dielectric permittivity of Ca2TiCrO6 ceramics.

A colossal permittivity ceramic material, Ca₂TiCrO₆, was successfully synthesized by the conventional solid-state reaction, and was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray photoemission spectroscopy (XPS) and x-ray diffraction (XRD). Rietveld refinement of XRD data indicated that the material crystallized in orthorhombic structure with space group pbnm. SEM displayed Ca₂TiCrO₆ ceramic grains packed uniformly with the size range 5-20 μm. XPS analyses indicated that elemental chromium and titanium of the material were in mixed valence. The corresponding dielectric property was tested in the frequency range 1 kHz-1MHz and the temperature range 213-453 K, and the ceramics exhibited a relaxation-like dielectric behaviour. Importantly, the permittivity of Ca₂TiCrO₆ could reach 80 000 at 298K (100 Hz) and was maintained at 40 000 up to 398K at 1 MHz, which could be attributed to the ion disorder and mixed valence of Cr³⁺/Cr⁶⁺ and Ti³⁺/Ti⁴⁺. [ABSTRACT FROM AUTHOR]