Optical, Dielectric, and Electromagnetic Microwave Absorption Properties of Hexagonal Ba₃(VO₄)₂

Abstract

We used a simple sol-gel synthesis technique to prepare hexagonal Ba3(VO4)2. X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman spectroscopy were performed, confirming that Ba3(VO4)2 has a hexagonal structure. To investigate the influence of interfacial interactions at grain boundaries on microwave absorption, atomic force microscopy studies were performed. UV-Vis studies show the direct and indirect optical energy band gaps of Ba3(VO4)2 were determined as 3.81and 3.25 eV, respectively. The dielectric studies reveal that the dielectric constant (ε׳) of Ba3(VO4)2 ranges from 1.55 to 6.02 in the frequency range of 2-20 GHz, with an average ε׳ value of 3.84. The microwave absorption properties of Ba3(VO4)2 were evaluated in the frequency range of 8-18 GHz, covering the X and Ku bands at different thicknesses from 4.5 to 8 mm. The highest effective absorption bandwidth (EAB) of 4.44 GHz was observed within the frequency range of 12.83-17.27 GHz, with a maximum reflection loss of -71.43 dB at a resonance frequency of 15.05 GHz. Additionally, at a thickness of 7.5 mm, Ba3(VO4)2 achieved a maximum reflection loss of -75.22 dB at 10.03 GHz, with an EAB of 2.94 GHz (covering the X band from 8.57 GHz to 11.51 GHz).

Microwave Absorption Properties of Hexagonal Ba3(VO4)2 through Zn Doping: A Comprehensive Analysis of Ba3–xZnx(VO4)2

“…Notably, at 836 and 891 cm −1 , the prominent peaks correspond to the symmetric (v 1 ) and asymmetric (v 3 ) stretching vibration modes of the VO 4 3− tetrahedra, characterized by A 1g symmetry. 29 These spectral features, which are intrinsic to the VO 4…”

“…3− groups, suggest robust bonds that influence the dielectric characteristics imperative for the microwave absorption of the material and its frequency response. 29 Additional peaks at 780, 418, 381, and 330 cm −1 are attributed to various V-O bond stretching and bending modes. The shifts in these Raman active modes, due to Zinc (Zn) substitution, may modify the dielectric properties, thus potentially enhancing the material's capability for microwave absorption.…”

“…4b, the FTIR spectrum of Ba 3-x Zn x (VO 4 ) 2 showcases a small peak at 3725 cm −1 that is indicative of O-H stretching vibrations, likely residues from citric acid and water. 29 The minor O-H stretch peak at 3725 cm −1 requires minimization given the potential impact of hydroxyl groups on the material's dielectric constant, pivotal for microwave absorption. While the peaks related to organic contaminants such as C-H, N-H, and C-O stretches do not influence microwave absorption directly, they do provide insights into the purity and synthesis quality of the material; hence, reducing these impurities is essential for maintaining consistent material properties.…”

“…In this study, Ba 3-x Zn x (VO 4 ) 2 (x = 0.05, 0.1, 0.15 and 0.2 mol%) powder samples were prepared using the sol-gel synthesis technique, as detailed in our previous study. 29 High-purity analytical reagent grade materials, Barium acetate (Sigma Aldrich), Ammonium metavanadate (SRL chemicals), Zinc Acetate (SRL chemicals), and Citric acid Anhydrous (SRL chemicals) with a purity above 99%, were utilized for the preparation process. The preparation involved dissolving Barium acetate, Zinc acetate, and Ammonium metavanadate in distilled water in a 500 ml beaker, followed by the addition of citric acid in a 1:1 ratio.…”

“…[26][27][28] Our recent study focused on the optical, dielectric, and electromagnetic microwave absorption properties of Hexagonal Ba 3 (VO 4 ) 2 . 29 Furthermore, enhancing the properties of Hexagonal Ba 3 (VO 4 ) 2 through doping shows promise in extending its applicability. We hypothesize that Zn doping could positively impact its structural integrity, optical absorption, and dielectric properties.…”