Microstrip antenna on a high dielectric constant substrate: BaTiO3 (BTO)-CaCu3Ti4O12(CCTO) composite screen-printed thick films

The performance of microstrip antennas using composite thick films of (BTOBaTiO3) and CCTO (CaCu3Ti4O12) as a substrate were studied. The dielectric permittivity and loss of (BTO)(x)-(CCTO)(1-x) thick films with x = 0, 0.2, 0.5, 0.8, 0.9, and 1 were examined. These films were prepared in two-layer geometry using the screen-printing technique on Al2O3 substrates. Mechanical alloying followed by the solid-state procedure was successfully employed to produce powders of CCTO (CaCu3Ti4O12) used in the films. We also studied the films dielectric permittivity (K) and loss (D) in the medium-frequency (MF) range (100 Hz to 1 MHz). The performance of a planar microstrip antenna that uses the (BTO)(x):(CCTO)(1-x) thick films as a substrate of high K was also examined in the microwave range of frequencies. From the analysis of the antenna operation of the samples, one can conclude that the higher values of K in the range of 2.5-3.3 GHz antennas is presented by the BTO substrates. For the BTO film, the K value is similar to 66 (2.6 GHz) and decreases to 34 for the CCTO film (3 GHz). For the BTO and CCTO films, the antenna bandwidths (BW) are similar to 50% and similar to 38%, respectively. The higher bandwidth presented by the BTO compared to the CCTO is certainly associated with the higher loss presented by the BTO phase, which is a ferroelectric phase. Therefore, these measurements confirm the potential use of such materials for small microwave planar antennas, where the miniaturization of the devices is crucial.35101848185

Microstructural and electrical properties of PbTIO3 screen-printed thick films

In this article we will study the structural and electrical properties of PbTiO3 (PTO) screen-printed thick films. These properties can change with synthetic routes employed for synthesis of PTO. The ceramic powder has been synthesized by mechanical alloying and solid state route. This material crystallizes in the tetragonal system, with space group P4mm and unit cell dimensions a = b = 3.904, c = 4.152 angstrom, and Z = 1. From our results, it was observed that PTO obtained by mechanical alloying provides smaller crystallite size. The Rietveld refinement showed that the samples synthesized by mechanical alloying and solid state route crystallize in the tetragonal system but with different cell parameters. The Raman shifts of these films agree with modes from literature. However, some displacements happen, because the morphology and structural characteristics of the thick films are different, compared to single crystal and thin film. The photomicrographs of the PTO thick films showed that the choice of synthetic routes obtained samples with different microstructures.191097398