No abstract

Zinc aluminate (ZnAl2O4) is a well-recognized ceramic demanded in several microwave applications. Further, the addition of dielectric materials in ZnAl2O4 improved its dielectric properties, which is promising for the realization of a microstrip patch antenna. This article reports the investigation of ZnAl2O4TiO2 (ZAT) dielectric ceramic nanoparticles synthesized by the sol–gel process. The X-ray diffraction analysis revealed the crystalline nature of the prepared nanoparticles, with a tetragonal structure of anatase-, and rutile-TiO2 phases coexisting with the cubic phase of ZnAl2O4. The estimated crystallite size of the dielectric ceramic is 13.3 nm. Transmission electron microscopy (TEM) micrographs demonstrated the spherical grains with their mean diameter of 14.75 nm, whereas the selected-area electron diffraction (SAED) pattern endorsed the crystallinity of the sample. Raman measurement revealed the vibrational modes in accordance with the TiO2 and ZnAl2O4 compounds. The dielectric properties of the ZAT sample showed the dielectric permittivity in the range of 22.12–21.63, with its minimum loss from 0.056 to 0.041. Finally, a prototype microstrip antenna was fabricated using the prepared nanoparticles, which demonstrated a return loss of − 30.72 dB at the resonant frequency of 4.85 GHz with its bandwidth of 830 MHz.

This Letter reports the synthesis of nanoceramic composite ZnAl 2 O 4 TiO 2 by using a cost-effective and straight forward sol-gel route. X-ray diffraction (XRD) showed the ZnAl 2 O 4 cubic structure along with the mixed anatase-and rutile-phases of TiO 2. Rietveld refinement is performed using XRD pattern to study the structural parameters. Raman investigation endorsed the corresponding vibration peaks of TiO 2 and ZnO. Field-emission scanning electron microscopy evidenced the agglomerated spherical nanoparticles. Energy-dispersive spectroscopy analysis demonstrated the elementary peaks of Zn, Al, and Ti at 4.5, 1.5, and 1 eV, respectively. LCR measurement revealed the decreased dielectric permittivity with the rise in frequency and temperature. This dielectric characteristic is attributed to the dipole movement of the charge carriers. Furthermore, the authors present the investigation of the conductivity and impedance of the prepared dielectric ceramic material.

This paper reports the sol–gel preparation of ZnAl 2 O 4 (ZA) and ZnAl 2 O 4 –TiO 2 (ZAT) dielectric ceramic nanoparticles for fabricating prototype microstrip patch antennas. The prepared nanoparticles were polycrystalline in nature with their crystallite sizes of 9.4 and 11 nm, along with average grain diameters of 16 and 12 nm corresponding to samples ZA and ZAT. Dielectric properties were investigated using an LCR meter, which endorsed enhanced dielectric permittivity and decreased dielectric loss. Finally, prototype microstrip patch antennas named AZA and AZAT were fabricated using the prepared nanoparticles, and their performances were evaluated. Both antennas exhibited resonant peaks in the frequency range from 6.4 to 6.5 GHz. The antenna AZAT showed a return loss of −37.07 dB with a voltage standing wave ratio (VSWR) of 1.02 compared to the return loss of −19.42 dB, and a VSWR of 1.24 corresponds to AZA. The AZAT antenna’s improved return loss can be regarded as the increased dielectric permittivity and reduced tangent loss of the ZAT sample. Furthermore, the ZAT antenna evidenced increased/decreased forwarded/reflected power decreased reflection coefficient and an optimal VSWR value compared to that of the AZA antenna.

No abstract