Propriedades dielétricas das eletrocerâmicas YTaO4 E Y3TaO7 para aplicação em dispositivos eletrônicos

Abstract

Technological advances have resulted in an increase in the consumption of rare earths (RE), which are used in the manufacture of cell phone screens, computers, wind turbines, among others. Among these classes, the following stand out: RE orthotantalates and tantalates, represented by the general formula TRTaO 4 and TR 3 TaO 7 , respectively. These are strong candidates for technological applications due to the possibility of obtaining a wide variety of compounds with different compositions. In addition, the properties of these compounds can be modified depending on the RE element in the composition. This research studied the synthesis process of the electroceramics YTaO 4 (monoclinic, I12/a1) and Y 3 TaO 7 (orthorhombic, C222 1 ) by solid state reaction, where their phases were confirmed by X-ray Diffraction (XRD), with the aim of investigating their dielectric properties in the radiofrequency (RF) and microwave (MW) ranges. In the morphological characterization, porous surfaces with well-defined grains and grain boundaries were observed. The Nyquist diagram showed non-Debye relaxation processes induced by a thermally activated mechanism, which were modeled by a parallel R-CPE equivalent circuit for both samples. The dielectric resonator antennas (DRAs) presented high dielectric permittivity (ɛ’) ≥ 10, and low dielectric loss tangent (tg δ) desired for MW (300 MHz à 300 GHz) application. The measurements of the temperature coefficient of the resonant frequency (τ f ) for YTaO 4 (τ f = - 18.69 ppm.oC -1 ) and Y 3 TaO 7 (τ f = 31.24 ppm.oC -1 ) confer the samples with the thermal stability required for their application in MW. Furthermore, these values allow obtaining DRAs in future research with τ f ~ 0. The antenna parameters of the electroceramics were obtained by numerical simulation, where they presented Reflection Coefficient (S 11 ) of -41.84 and -44.62 dB; Bandwidth (BW) of 55.00 and 9.58%; Efficiency of 99.45 and 91.87%; Directivity of 6.03 and 5.90 dBi and Gain of 6.0 and 5.53; respectively. Therefore, the evaluation of the dielectric behavior of the electroceramics with possible application in electronic devices, such as capacitors and DRAs, indicated great potential for application in the MW and RF region.