High Value Of Dielectric Constant Research Articles

Enhanced structural, optical, dielectric, and electrical properties of CoFe2O4 nanostructures: Effect of variation of citric acid concentration

In the current work, the authors report on the facile synthesis of CoFe2O4 (CFO) nanoparticles (NPs) with different citric acid (CA) concentrations and at a constant temperature. The synthesized nanostructures were investigated for structural, vibrational, morphological, opto-dielectric, and electrical characteristics. X-ray diffraction analysis confirmed their cubic structural phase, while allowing other microstructural parameters to be investigated. The crystallite size based Scherrer and W–H plot methods ranged from 23 to 30 nm and 21–30 nm, respectively, and declined with the increase in CA concentration. The vibrational analysis confirmed the pure phase of CFO at all CA concentrations. Diffused reflectance spectra were measured to determine the bandgap energy of CFO NPs, which increased from 2.10 to 2.35 eV as the CA content increased, whereas CFO NP grain size declined, as confirmed by SEM measurements. EDX analysis and SEM e-mapping study further revealed that the CFO was synthesized with proper composition. According to the dielectric and electrical studies (performed up to 10 MHz), the dielectric constant ranged from 130 to 160, and the highest value was obtained for CFO containing 0.25 g of CA. Finally, the frequency exponent indicates the CBH model of carrier charge conduction mechanism in the CFO samples. Therefore, the low particle size, wide bandgap, and high dielectric constant values of the synthesized CFO NPs make them suitable candidates for optoelectronic applications.

A deep dive into structural, electronic, optical, and mechanical properties of ATiO3 (A = Ba, Th): DFT insights

Different physical characteristics (structural, optical, electronic, and mechanical) of ThTiO3 were explored using DFT and compared to BaTiO3. ThTiO3 has been determined to be mechanically and thermodynamically stable based on the simulation results, which were validated using the Born stability criteria and formation energy. Furthermore, a significant modification in the traits of ThTiO3 has been revealed compared to BaTiO3. For example, after the complete substitution of Ba by Th, in the case of GGA-PBE, the band gap increases from 1.82 eV to 3.37 eV, while in the case of HSE-06, it increases from 3.254 eV to 4.21 eV, also converting from indirect to direct bandgap. Not only that, but ThTiO3 has become an n-type degenerate semiconductor from a conventional semiconductor, which assures potential applications in tunnel diodes, high-frequency transistors, photocatalysts, etc. ThTiO3 is an appropriate material for capacitors, optoelectronic, and high k nanoelectronics devices based on the high dielectric constant value, which is higher than BaTiO3. Moreover, with Th substitution, BaTiO3 transitioned from brittle to ductile, which ensures its suitability for industrial machining processes. Furthermore, this substitution also improved the material’s anisotropic behavior, as the Zener Anisotropy value for ThTiO3 is also higher than BaTiO3. We believe this investigation will open another door in the field of materials for microelectronics and optoelectronics enthusiasts.

Low-dimensional lead chromate-based hybrid system for capacitance and polarization performances: a flexible device for pressure-induced voltage generator

AbstractOrganic molecule–functionalized lead chromate nanoparticle was synthesized using a complexation strategy route. The structural characterization revealed the single-phase lead chromate system belongs to monazite-type monoclinic structure with the space group of P21/n. The unit cell consists of an alternating chain of polyhedra (PbO9) and tetrahedra (CrO4) units, connected via edge and corner-sharing arrangement. A flexible device of lead chromate was fabricated and investigated dielectric capacitance, electrical impedance, conductivity, and field dependent polarization performances under different frequency and temperature environments. The device displayed a maximum dielectric constant (εʹ) value ~ 2400 at 120°C under 100 Hz frequency condition. High dielectric constant value is originated from the orientation polarization of CrO4 unit and space charge contribution in the system. AC conductivity of the device suggested the polaronic charge carriers control the overall conduction process via localized hopping mechanism. A fatigue-free polarization behavior was observed in the device under the applied field of 4.0 kV/mm, for 103 cycles and retained the polarization value ~ 0.26 μC/cm2 over the switching cycles. Lead chromate–based device also showed pressure-induced voltage generation under different pressure conditions and could have the potential application as a voltage generator.

Magnetoelectric coupling response of novel mullite coated Ni–Zn–Cu-ferrite nanocomposite

Novel multiferroic nanocomposite fabricated by Ni–Zn–Cu-ferrite (NZCF)-mullite is reported in this article. The crystallographic phases are confirmed by X-ray diffraction. The static magnetic properties are measured for both bare NZCF and mullite encapsulated NZCF nanocomposite which show the successful retention of the magnetic behaviors of the nanocomposites even at higher annealing temperature of 1200 °C. The dielectric response is estimated and high value of dielectric constant (∼210.7 at 100 Hz) is observed for the mullite encapsulated NZCF nanocomposite due to the formation of interfacial polarization in the nanocomposite. The temperature dependent dielectric response suggests the presence of dielectric polarization in the NZCF-mullite nanocomposite. Magnetocapacitance (MC) study of the NZCF-mullite nanocomposite sample is observed at room temperature (RT). The observed MC and its variation with magnetic field confirm the presence of strong interactions between the magnetic and ferroelectric order parameters in the nanocomposite sample.

Growth of gallium cerium oxide passivation layer on 4H-Silicon carbide substrate and its metal-oxide-semiconductor characteristics

Gallium cerium oxide (GaxCeyOz) passivation layer was successfully grown on 4H-silicon carbide (SiC) through postdeposition annealing at 800 °C in nitrogen-oxygen-nitrogen (N2–O2–N2) ambient. The gracing incident X-ray diffraction and ultraviolet–visible spectrophotometer measurements have confirmed the successful incorporation of Ga3+ cation into the CeO2 lattice to form the ternary GaxCeyOz passivation layer. In addition, the thicknesses of GaxCeyOz passivation layer and silicon dioxide (SiO2) interfacial layer (IL) were determined using field-emission scanning electron microscopy and X-ray reflectivity characterizations. A high dielectric constant (k) value of 24.11 was attained for the investigated Al/GaxCeyOz/4H–SiC/Al metal-oxide-semiconductor (MOS) structure attributable to the nitrogen ions accumulating at the interface that have retarded the growth of SiO2 IL. Besides, the effective oxide charge, slow trap density, interface trap density, interface state density, as well as leakage current density-electric field characteristic of the investigated GaxCeyOz passivation layer on 4H–SiC substrate was presented in this work.

Fractal Approach to Dielectric Properties of Single Walled Carbon Nanotubes Reinforced Polymer Composites

In this paper, the internal structure and dielectric properties of unsaturated polyester resin-based neat and single-walled carbon nanotube reinforced composites were comprehensively evaluated with the fractal analysis using the Fast Fourier Transform (FFT). The greyscale images, bitmap (BMP) images and 3D tomographic images were obtained by converting the scanning electron microscope images of the materials. It was observed that the distributions of components in the resin for both materials are irregular and their surfaces exhibit anisotropic behaviors. The surface coating rate (SCR) and fractal dimensionality (FD) of the materials were also calculated using the power spectrum. It has been observed that the fractal dimensionality of the composites can be changed by the doping process and the fractalization of the nanotube doped sample increases compared to the pure material due to nanotube agglomeration, spatial distribution and the orientation. The increase in fractalization as a result of this agglomeration and orientation in carbon nanotubes explains the high dielectric constant values observed at low frequencies by increasing the number and size of carbon nanotubes clusters that act as micro capacitors in certain regions of the matrix. It has been reported that the calculations for the surface coverage ratios for both samples also support these results.

Fabrication and Characterization of Dielectric ZnCr2O4 Nanopowders and Thin Films for Parallel-Plate Capacitor Applications.

We report here the successful shape-controlled synthesis of dielectric spinel-type ZnCr2O4 nanoparticles by using a simple sol-gel auto-combustion method followed by successive heat treatment steps of the resulting powders at temperatures from 500 to 900 °C and from 5 to 11 h, in air. A systematic study of the dependence of the morphology of the nanoparticles on the annealing time and temperature was performed by using field effect scanning electron microscopy (FE-SEM), powder X-ray diffraction (PXRD) and structure refinement by the Rietveld method, dynamic lattice analysis and broadband dielectric spectrometry, respectively. It was observed for the first time that when the aerobic post-synthesis heat treatment temperature increases progressively from 500 to 900 °C, the ZnCr2O4 nanoparticles: (i) increase in size from 10 to 350 nm and (ii) develop well-defined facets, changing their shape from shapeless to truncated octahedrons and eventually pseudo-octahedra. The samples were found to exhibit high dielectric constant values and low dielectric losses with the best dielectric performance characteristics displayed by the 350 nm pseudo-octahedral nanoparticles whose permittivity reaches a value of ε = 1500 and a dielectric loss tan δ = 5 × 10-4 at a frequency of 1 Hz. Nanoparticulate ZnCr2O4-based thin films with a thickness varying from 0.5 to 2 μm were fabricated by the drop-casting method and subsequently incorporated into planar capacitors whose dielectric performance was characterized. This study undoubtedly shows that the dielectric properties of nanostructured zinc chromite powders can be engineered by the rational control of their morphology upon the variation of the post-synthesis heat treatment process.

Microwave-assisted synthesis of praseodymium (Pr)-doped ZnS QDs such as nanoparticles for optoelectronic applications.

Praseodymium (Pr)-doped ZnS nanoparticles were synthesized using a low-cost microwave-assisted technique and investigations on their structure, morphology, optical properties, Raman resonance, dielectric properties, and luminescence were conducted. Broad X-ray diffraction peaks suggested the formation of low-dimensional Pr-doped ZnS nanoparticles with a cubic structure that was validated using transmission electron microscopy (TEM)/high-resolution TEM analysis. The energy gaps were identified using diffuse reflectance spectroscopy and it was found that the values varied between 3.54eV and 3.61eV for different samples. Vibrational experiments on Pr-doped ZnS nanoparticles revealed significant Raman modes at ~270 and ~350 cm-1 that were associated with optical phonon modes that are shifted to lower wavenumbers, indicating phonon confinement in the synthesized products. The photoluminescence (PL) spectra of all samples demonstrated that the pure and Pr-doped ZnS nanoparticles were three-level laser active materials. Energy-dispersive X-ray spectroscopy and mapping study confirmed the homogeneous presence of Pr in ZnS. TEM studies showed that the particles were of very small size and in the cubic phase. The samples had high dielectric constant values between 13 and 24 and low loss values, according to the dielectric analysis. With an increase in frequency and a change in the Pr content of ZnS, an intense peak could be seen in the PL spectra at a wavelength of 360 nm, and some other peaks observed corresponded to the transition of Pr3+ . The produced nanoparticles were appropriate for optoelectronic applications due to their short dimension, high energy gap, high dielectric constant, and low loss values.

Temperature and frequency dependent dielectric capacitance and polarization performances of low dimensional perovskite based manganese stannate

Manganese stannate perovskite nanoparticles were synthesized by applying a complexation mediated approach. Rietveld refinement of the XRD data exhibited orthorhombic structure with space group of Pnma. The structure included eightfold coordinated Mn2+ cation, surrounded by eight O2− anions and formed MnO8 polyhedra unit. Each polyhedra unit interconnected through the corner-sharing SnO6 octahedra with the formation of a cage-like network. The temperature and frequency dependent dielectric performances of manganese stannate were measured in the form of a device, which exhibited maximum dielectric constant value ~ 3445. The high dielectric constant value was originated due to the contribution of space charge polarization and orientation polarization of dipoles within the measured frequency ranges. Temperature and frequency dependent AC-conduction mechanism of the manganese stannate-based device involved both overlapping large polarons and non-overlapping small polarons. Electric field-dependent of polarization hysteresis loop of the device exhibited the maximum polarization value 1.5 µC/cm2 under the electric field of 3 kV/mm. Under the applied field of 2 kV/mm, the device exhibited a fatigue-free polarization with a maximum value of 0.92 µC/cm2, sustained for 103 cycles under ambient temperature condition.

Robust ferromagnetism and magneto-dielectric anomalies in (Al, Cr) co-doped iron oxide thin films-microwave mediated sol–gel approach

Research on thin films of iron oxide has gained interest in recent years because of its application in advanced spintronic and electronic devices. Technologically important iron oxide phases can be achieved by adopting novel methodologies and/or selecting suitable dopants. A cost-effective microwave assisted sol–gel approach is adopted in this work to prepare thin films of iron oxide. Undoped and doped sols (2–10 wt% of dopant concentration) are irradiated with MW power of 720 W. Maghemite phase (γ-Fe2O3) is observed to be stable up to a co-dopant concentration of 6 wt%. Further increase in dopant content leads to a phase transition to mixed (γ-Fe2O3+Al2O3) crystal phases. Values of dielectric constant (DC) and loss tangent exhibit normal dispersion response with high DC value (log f 5.5 = ∼92) observed for undoped sample. Cole–Cole plots indicate the effective grain boundary contribution for low dopant concentrations, whereas contributions from grains is observed at higher dopant concentrations. M−H curves show ferromagnetic response with high value of saturation magnetization (Ms) of ∼450 emu/cm3 witnessed at 6 wt%. (Al, Cr) co-doping results in tuning of magnetic response/parameters. MD coupling of (Al, Cr) co-doped thin films of iron oxide makes this material suitable for advanced spintronic and energy storage devices.

Electrolyte-Insulator-Semiconductor (EIS) Device with Hafnium Dioxide (HfO2) for pH Detecting

In this work Electrolyte-Insulator-Semiconductor (EIS) device has been developed for pH measurements. This device operates as a Metal-Oxide-Semiconductor capacitor but instead of having the metal contact electrode, an electrolyte solution and a reference electrode are used to apply voltage. As dielectric material and sensitive membrane was chosen hafnium dioxide (HfO2). This film was obtained by RF sputtering, and was structurally characterized by Raman and Ellipsometry. The structural characterization of HfO2 thin film shows the presence of tetragonal phase, physical thickness of 50 nm and refractive index of 1.89, close to stochiometric of 1.91. Was developed MOS capacitors to make the electrical characterization of HfO2 thin films in order to determine the thin film properties, defined by high dielectric constant value (high-k), lower charge density (Q0/q) and flat-band voltage (VFB) around -0.9V. The electrical characterization done by Capacitance x Voltage (CxV) curves revealed high dielectric constant, VFB of 0.02V and Q0/q in the order of -10+12/cm2. The Current x Voltage (IxV) curve shows that the current through the dielectric is approximately 1x10-9A. With dielectric characterized it was possible to develop the EIS device. From electrical characterization it was possible to test the integrity of the electrodes and determined the sensitivity of the device. For electrical measurement of EIS was used Normalized Capacitance x Voltage curve (CxV curve) using different pH (3, 4, 5, 7, 9, 10 and 12) solutions. From the flat band voltage (VFB) of the Normalized CxV curves was possible to determine the sensitivity of the device of 78mV/pH. This result is greater than the Nernst level and greater than results found in the literature.

Enhanced dielectric permittivity of novel ternary La2Cu–AgO4 nanocomposites with different ratios of 2-D Borophene nanofiller

Borophene is a monolayer of boron atoms that exhibits notable physical and chemical characteristics, making it the lightest two-dimensional material known to date. Simultaneously, the compositions of silver-copper oxide and lanthanum-copper oxide exhibited unique applications. The present study was motivated by the need to investigate the potential benefits of combining La2Cu–AgO4 ternary nano composition with 2-D Borophene. The successful synthesis of La2Cu–AgO4 nanoparticles and 2-D Borophene has been achieved through simple and cost-effective methods. The La2Cu–AgO4/Borophene composite, with varying weight percentages, has been subjected to various characterization techniques for analysis. The electrical properties of the prepared samples were analyzed. The present study indicates that Borophene has enhanced the dielectric properties of La2Cu–AgO4 nanoparticles by a factor of approximately 2–5. An additional fascinating characteristic of the La2Cu–AgO4/Borophene nanocomposites that were prepared is the presence of a negative Schottky barrier, which exhibits a small value. The incorporation of 2-D Borophene resulted in a reduction of the resistivity of La2Cu–AgO4 by 14–17% compared to its initial value. Moreover, in comparison to the pure La2Cu–AgO4 ternary nanocomposite, the nanocomposite samples of 2-D La2Cu–AgO4 demonstrated reduced activation energy, potential barrier height, and density. The results obtained from the study demonstrate that the material possesses a high dielectric constant value, low resistance, and is lightweight and cost-effective. These properties make it a promising candidate for use in telecommunications and solid-state semiconductor applications, as it can be easily applied.

Synthesis and structural characterization of azine based oligoesteric chemosensors for Fe2+ ion detection

AbstractAzine‐based monomer and its three oligoesters were synthesized, characterized with IR, UV, GC‐MS, GPC, 1H NMR, 13C{1H} NMR, 31P NMR and applied to chemosensor applications. In the chemosensor study, fluorophores show selective and sensitive responses with Fe2+ ions in the DMF/H2O solution (1 : 1, pH: 7.4, fluorophore: 5 μM). The quenching of fluorescence intensity with the addition of Fe2+ ion gives the correlation coefficient (R2) value above 0.99286, exhibiting good binding stoichiometry nature of fluorophores with Fe2+ than the oligoesters. The high detecting capability of oligoesters is further ascertained by its higher LOD than the monomer (5.05×10−7). The binding constant values of fluorophores obtained from the Benesi‐Hildebrand plot show that the oligoesters have a higher binding ability (1.0012–1.0025 M−1) with Fe2+ ion than the monomer (1.0011 M−1). The conductivity nature of the oligoester gradually increased with the contact time of iodine. After 96hr of iodine doping, EMDAP exhibits higher conductivity (1.98×10−3 Scm−1) than the other oligoesters due to higher electron‐density nitrogen atoms in the structure. The EMDOP shows high dielectric constant value because of its π‐π interaction, loosely attached π electrons and high dipole moment values. All these experimental results are validated with the theoretical (DFT) approach by optimizing the structure of the fluorophore with B3LYP/6‐311++G(d,p) level basis set. The DFT approach also explains the mechanism of fluorescence quenching and the exact binding sites of fluorophores with Fe2+ ions.

Effect of 'Ca' in dielectric, optical, and magnetic behavior of BaFe0.5Nb0.5O3 for possible device applications

In this present work, the Ca-doped BaFe0.5Nb0.5O3 perovskite is synthesized through the typical solid solution route and a thorough investigation of its structural, optical, dielectric, electrical, and magnetic properties is carried out. Basic structural analysis through X-ray diffraction technique reveals that the sample has a monoclinic crystal symmetry (a = 4.7487 Å, b = 2.8465 Å, c = 5.7641 Å, V = 36.36 (Å)3, β = 101.45ᵒ, and space group = C1m1). Scanning electron microscopy and transmission electron microscopy techniques confirm the polycrystalline nature of the sample. Energy-dispersive X-ray spectroscopy reveals the constituent elements in the sample. Ultraviolet photoelectron spectroscopy is used to determine the sample work function. X-ray photoelectron spectroscopy specifies the existence of dual valencies of Fe and Nb in the sample which in turn validates several physical mechanisms. The optical bandgap energy is estimated as 1.97 eV through UV-Visible spectroscopy. A significantly high dielectric constant value is noted at room temperature in the lower frequency domain. Impedance spectroscopy unveils the non-Debye type of relaxation and negative temperature coefficient of resistance nature of the sample. Conductivity analysis provides insight into the significance of involved charge transporters. The room temperature magnetic investigation reveals the ferromagnetic property of the sample. In inference, the synthesized perovskite material can be declared as a potential option for multipurpose implementations.

Structure, thermal, hydrophobic, and dielectric properties of Bermuda grass ash bio‐silica, SBA‐15, and rGO‐reinforced bisphenol‐BA‐based polybenzoxazine composites

AbstractThe present work deals with the development of bisphenol‐BA based benzoxazines and to study their behavior toward utilization for thermal, high‐dielectric, low‐dielectric, and anti‐corrosion applications. A new type of bifunctional benzoxazine resins were synthesized using bisphenol‐BA with different types of amines and characterized using FTIR, 1H‐NMR spectra, DSC, and TGA techniques. In the present study, thermally stable bisphenol‐BA with trifluoromethylaniline benzoxazine (BBA‐tfma) and bisphenol‐BA with furfurylamine benzoxazine (BBA–ffa) were selected as matrices for the preparation of composites with SBA‐15, bio‐silica (from Bermuda grass) and reduced graphene oxide. The results indicated that the poly(BBA‐tfma) with 5 wt% SBA‐15 composites and poly(BBA‐ffa) with 10 wt% bio‐silica composites showed the lowest dielectric constant value of 1.71 and 1.87, respectively. While in contrast, the 5 wt% of reduced graphene oxide (rGO) reinforced poly(BBA‐tfma) exhibits highest value of dielectric constant (k = 8.49). Results from corrosion studies ascertain that the bisphenol‐BA with aminoethoxyethanol benzoxazine, that is, poly(BBA‐aee) possess better mild steel corrosion protection behavior than that of other benzoxazines. Data resulting from different studies indicate that the bisphenol‐BA‐based benzoxazines and their composites can be effectively used for different industrial applications.

Raveling out the effect of Pr3+ ions substitution on different properties of nano-sized hexagonal ferrites

The development of a new stable phase/type, a rare earth element Pr3+ substitution in Ca2-xPrxFe8O14 (T-type) of hexagonal ferrites with composition (x = 0.0, 0.02, 0.06, 0.1), using the sol–gel auto-combustion method was endeavoured in the current study. The x-ray diffraction analysis proved that all samples possess single-phase structures. All computed structural characteristics varied with Pr3+ substitution. The particles with random shapes and sizes were examined from TEM analysis and particle sizes ranged from 14 to 44 nm. With Pr-contents, the saturation and remanent magnetization increased and the coercivity decreased. All samples have high values of dielectric loss, dielectric constant, and tangent loss at low-frequency values and these high values declined with rising frequency. The peaks in real part of the electric modulus migrated toward the low-frequency region; it was the confirmation that grain boundaries are incredibly active to participate in resistance. The uneven trend in the imaginary part of the electric modulus, which is demised with increasing frequency and peaks, was described by the Sillars model. The band gap (Eg) of the samples reduced linearly from 4.60 to 4.32 eV with the addition of Pr3+ ions, as observed from the UV–visible absorbance spectra. The polarization vs electric field (P-E) loops of synthesized samples displayed lossy behavior and this loosy behavior decreased with Pr-additives. On the basis of properties exhibited by the present synthesized T-type hexagonal ferrites, it can be hoped that these materials are applicable in high-frequency devices, antenna, radar applications, and opto-magneto applications.

Dielectric relaxation and polaron hopping in biomass derived activated carbon

Activated carbon samples were obtained by alkali (KOH) activation and subsequent carbonisation of an identified biomass precursor at 600 °C, 800 °C, 1000 °C, and 1200 °C temperatures, in nitrogen atmosphere. Dielectric property changes with respect to the change in microstructure in the activated carbon samples was studied. High dielectric constant values at low-frequency regions (<103 Hz) were observed in all samples, due to trapped K+ ions, polar groups (C = C, C = O, –NH2, –OH), and interfacial polarisation. The trapped K+ ions also contributed to high dielectric dispersion at low-frequency regions. Carbonisation at 600 °C resulted in amorphous carbon formation with some intact cellulose crystallites. Thermal de-trapping of K+ ions resulted in an increase in dielectric constant with frequency up to 103 Hz. Carbonisation at 800 °C and 1000 °C resulted in nanocrystalline graphene oxide (GO), with interfacial polarisations dominant in charge storing and in the relaxation processes. Carbonisation at 1200 °C resulted in a carbon nanotube (CNT) network and negative dielectric constant values at 70 °C was observed due to the Surface Plasmon Resonance effects of the formed CNT. With increase in carbonisation temperature, a change in Debye-type to non-Debye-type relaxation process was observed, supported by the Dielectric formalism studies and the Cole–Cole plot.

Temperature-dependent dielectric measurements and structural properties of barium stannate (BaSnO3)

Cubic perovskite BaSnO3, synthesized by solid-state reaction method, was structurally characterized using temperature-dependent X-ray and Raman spectroscopy studies along with room temperature neutron diffraction analysis. Here, we report the effect of temperature on the structural parameters of BaSnO3 in correlation with dielectric properties. Sample homogeneity and elemental composition were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy methods. The compound maintains cubic symmetry even at high temperatures and exhibits gradual increase in unit cell volume owing to thermal expansion. To understand high temperature phase transition, if any, and capacitance behavior, high temperature dielectric measurements were carried out. High value of dielectric constant was obtained at low frequencies as the temperature was increased, which may be due to the presence of oxygen vacancies or the lone-pair effect.

CHARACTERIZATION OF ENERGY BAND GAP THIN FILM BaTiO3 – BaZr0.5Ti0.5O3 USING DIFUSION REFLECTANCE SPECTROSCOPY (DRS) METHOD

Ferroelectric material is a dielectric material that has a high dielectric constant value so that it can be made in the form of thin films. Its application is based on electro-optical properties, one of which is the infrared thermal switch. This paper aims to determine the bandgap energy (Eg) of a 0.3BaTiO3 – 0.7BaZr0.5Ti0.5O3 thin film. The 0.3BaTiO3 – 0.7BaZr0.5Ti0.5O3 thin film is a semiconductor material with the valence band and conduction band separated by an energy bandgap (Eg). Thin films of 0.3BaTiO3 – 0.7BaZr0.5Ti0.5O3 were grown on FTO substrates using the sol-gel method. The films of 0.3BaTiO3 – 0.7BaZr0.5Ti0.5O3 were annealed at different temperatures of 700°C, 750°C and 800°C within 1 hour. Characterization was carried out using Ultra Violet Visible (UV-Vis) spectroscopy to determine Eg using the Diffusion Reflectance Spectroscopy (DRS) method. The DRS method was found to be better for solid materials considering the scattering component. The UV-Vis characterization results show that an increase in annealing temperature causes a decrease in Eg. For example the values ​​at 700°C, 750°C and 800°C are 3.5 ± 0.01 eV; 3.3±0.01 eV and 3.2±0.01 eV. The decrease in Eg is related to the diffusion of Barium Titanate (BaTiO3) ions into the Barium Zirconium Titanate (BZT) lattice forming a new sub-gap which in turn gives BT-BZT the ability to absorb lower light. Lower light absorption means more capable optics for multilayer systems.

ZnS nanoparticles: role of Ga3+ ions substitution on the structural, morphological, optical, and dielectric properties

Due to their dynamic features, nanoparticles of semiconductor materials have been created rapidly in the past few decades and are being investigated for potential uses in a variety of disciplines. The present study focuses on the substitution of Ga3+ ions in ZnS nanoparticles to modify their structural, morphological, compositional, optical, and dielectric properties. The Ga-doped (ZnS:Ga) nanoparticles for various Ga3+ ions concentrations (i.e., 0%, 2%, 4%, 6%, 8%, 10% & 12%) are synthesized using direct co-precipitation technique and utilizing precursor solutions of Zn(CH3COO)2, Na2S and Ga2(SO4)3 along with EDTA as a stabilizing agent. The structural analysis reveals that the synthesized nanoparticles exhibit a cubic crystal structure with high crystallinity and preferred (111) orientation. Fluctuations in different structural parameters have been noticed without any alteration in crystal structure after the substitution of Ga ions in ZnS matrix. The surface morphology exposes spherical-shaped ZnS:Ga nanoparticles whose compactness varies with doping concentrations. FT-IR and EDS spectra of the nanoparticles identify the presence of different functional groups and elements in the expected compositions. A blueshift in the absorption edge has been observed for all the concentrations of ZnS:Ga w.r.t. pristine ZnS indicating quantum confinement in the synthesized nanoparticles which further results in the broadening of optical bandgap in comparison to bulk value for ZnS. The room temperature dielectric measurements for ZnS:Ga nanoparticles show a high dielectric constant value up to doping level 8% beyond which it decreased. The ac conductivity values in this study varied from 10−4 Ω−1m−1 for pristine to 9.66 × 10−3 Ω−1m−1 for ZnS:Ga 12%.