Tailorable radio-frequency negative permittivity of titanium nitride sintered with different oxidation pretreatments

Titanium nitride (TiN) with high-temperature plasmonic property can be a promising candidate for metamaterials at radio-frequency region. In this paper, pure TiN powders were pretreated by a facile oxidation process . The introduced titanium oxide was in favor of sintering of TiN, and further controlled the dielectric properties of TiN bulks. The radio-frequency (10   MHz-1   GHz) permittivity spectra of the obtained samples were investigated in detail. Negative permittivity was achieved using TiN based ceramic and it was tailorable by the oxidation temperatures of powders before sintering. The negative permittivity induced by plasma oscillations of conductive electrons was analyzed by Drude model. Interestingly, the zero-crossing points of permittivity from negative to positive were depend on the porous microstructure and weakly conductive titanium oxynitride , as well as the scattering effect by grain boundaries and impurity atoms. The conduction loss is dominant in determining the high dielectric loss. The realization of tunable negative permittivity using TiN gives a new and simple method to achieve negative electromagnetic parameters in single-phase materials.