A Zn2Te3O8 ceramic was investigated as a promising dielectric material for low‐temperature co‐fired ceramics (LTCC) applications. The Zn2Te3O8 ceramic was synthesized using the solid‐state reaction method by sintering in the temperature range 540°–600°C. The structure and microstructure of the compounds were investigated using X‐ray diffraction (XRD) and scanning electron microscopy methods. The dielectric properties of the ceramics were studied in the frequency range 4–6 GHz. The Zn2Te3O8 ceramic has a dielectric constant (ɛr) of 16.2, a quality factor (Qu×f) of 66 000 at 4.97 GHz, and a temperature coefficient of resonant frequency (τf) of −60 ppm/°C, respectively. Addition of 4 wt% TiO2 improved the τf to −8.7 ppm/°C with an ɛr of 19.3 and a Qu×f of 27 000 at 5.14 GHz when sintered at 650°C. The chemical reactivity of the Zn2Te3O8 ceramic with Ag and Al metal electrodes was also investigated.

Nominally Sr 2+n Ce 2 Ti 5+n O 16+3n dielectric ceramics were prepared by conventional solid-state ceramic route. The structure and microstructural features of the ceramics were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. At optimized sintering conditions, it is shown that Ce 4+ ions reduce to Ce 3+ ions, which leads to the correct formula Sr 2+n Ce 2 Ti 5+n O 15+3n for the materials. The ceramics present a cubic SrTiO 3 -like structure, where Ce 3+ ions and their associated vacancies randomly share the A-sites with the Sr 2+ cations. Therefore, this solid solution could be alternatively described by Sr 1-3x/2 Ce x TiO 3 , where x e 0.40 is not necessarily an integer. For 0 e n e 10 (0.40 > x > 0.133), these materials have dielectric constant and Q u xf in the range of 113-185 and 6000-11000 GHz (at 2 GHz), respectively. However, the relatively high positive temperature coefficients of resonance frequencies decrease substantially to values five times lower than those commonly observed for SrTiO 3 .

Sr 1-3x/2 Ce x TiO 3 dielectric ceramics (with x varying from 0.133 to 0.400) were investigated by Raman and infrared spectroscopies. The observed features could be related to SrTiO 3 phonon modes. The Raman spectra show first-order modes-which are modes either activated by polar defects or due to local symmetry lowering-together with classical second-order modes of SrTiO 3 . The infrared spectra are dominated by the three predicted polar phonons of SrTiO 3 , although a faint tetragonal distortion confirmed by lowtemperature measurements was observed for all compositions. For increasing Ce content, the infrared spectra show a continuous hardening of the TO modes and the softening of the highest frequency LO mode. Together with the broadening of the TO phonon lines, these phonon energy evolutions explain the observed dielectric behavior of the material: namely, the decreasing of the dielectric constant and temperature coefficient of the resonance frequency (τ f ) with x. The quality factor is maximized for x ) 0.25. Compared to pure SrTiO 3 , chemically substituted Sr 1-3x/2 Ce x TiO 3 ceramics present more adequate dielectric properties at microwave frequencies for technological applications.