Synthesis, Characterization, and Low Temperature Sintering of Nanostructured BaWO₄for Optical and LTCC Applications

Abstract

Synthesis of nano-BaWO4by a modified combustion technique and its suitability for various applications are reported. The structure and phase purity of the sample analyzed by X-ray diffraction, Fourier transform Raman, and infrared spectroscopy show that the sample is phase pure with tetragonal structure. The particle size from the transmission electron microscopy is 22 nm. The basic optical properties and optical constants of the nano BaWO4are studied using UV-visible absorption spectroscopy which showed that the material is a wide band gap semiconductor with band gap of 4.1 eV. The sample shows poor transmittance in ultraviolet region while maximum in visible-near infrared regions. The photoluminescence spectra show intense emission in blue region. The sample is sintered at low temperature of 810°C, without any sintering aid. Surface morphology of the sample is analyzed by scanning electron microscopy. The dielectric constant and loss factor measured at 5 MHz are 9 and1.56×10-3. The temperature coefficient of dielectric constant is −22 ppm/°C. The experimental results obtained in the present work claim the potential use of nano BaWO4as UV filters, transparent films for window layers on solar cells, antireflection coatings, scintillators, detectors, and for LTCC applications.

Dielectric and magnetic characteristics of Ca1−xMnxMoO4 (0 ≤ x ≤ 0.15) nanomaterials

“…These systems operating at high frequencies require new materials with relatively low dielectric permittivity ( ε r ), high-quality factor (Qxf) and stable and near-to-zero-temperature coefficient of resonant frequency ( τ f ), as well as co-fired with internal metal electrodes, i.e. Al, Ag or Cu (Kim et al 2006; Vidya et al 2013; Xi et al 2014; Choi et al 2007). In particular, a low value of ε r is important because a signal propagation velocity is a function of dielectric permittivity.…”

Irreversible thermochromic response of RF sputtered nanocrystalline BaWO4 films for smart window applications

“…20 Also, these calculated bandgap values are comparable with BWO nanoparticles (E g ∼ 4.1 eV) prepared by the modified combustion process. 16 From the above observations, it can be infer that the absorption edges of the films shifts towards lower energy side with an increase in deposition temperature, which is attributed to the increase in crystallinity and coloring effect. At 600 • C, the shift in absorption edge towards lower energies may be due to the increase of energy for the charge transfer from oxygen to tungsten.…”

“…The obtained refractive index values are in the range of 1.76 -2.1 @ 600 nm and are comparable with the reported values. 16,17 The variation in extinction coefficient and optical bandgap as a function of deposition temperature is depicted in Fig. 4(a).…”

Visible Light Photocatalytic Degradation of Methylene Blue and Malachite Green Dyes with BaWO4-Go Nano Composite

“…As the band gap is the energy difference between valance and conduction band, the presence of these intermediate levels resulted in the reduction of optical band gap energy. The BaWO4 prepared by the present method possess wide band gap along with good transmittance in the visible region which is suitable for transparent conducting oxide films of window layers on solar cells [31].…”

“…The well defined particle features of the tungstates synthesized by SSM reactions showed that these reactions have control ions. These particles are strongly interacted with cationic surfactants and played an important role in the morphology of BaWO4 products [31].…”