Wide Band Gap Energy Research Articles

Alicyclic Polyimide With Multiple Breakdown Self-Healing Based on Gas-Condensation Phase Validation for High Temperature Capacitive Energy Storage.

Polymer dielectrics with combined thermal stability and self-healing properties are specifically desired for high-temperature film capacitors. The high thermal stability of conventional polymers benefits from the abundance of aromatic rings in the molecule backbone, but the high carbon content sacrifices their self-healing properties. Here, analicyclic polyimide with a high glass transition temperature (256°C) and wide energy bandgap (4.58eV) is designed, which exhibits electric conductivity more than an order of magnitude lower than that of classical polyimide at high electric fields and high temperatures. As a result, alicyclic polyimide achieves a discharged energy density of 4.54 Jcm-3 and a charge-discharge efficiency of above 90% at 200°C, which is superior to existing dielectric polymers and composites. The alicyclic polyimide benefits from a low pyrolytic residual carbon rate, retaining 93% of the dielectric breakdown strength after four electrical breakdown cycles. Distinguishing from the current condensed-phase self-healing concept, for the first time, exploring the self-healing capability of high-temperature polyimide dielectric is presented based on dual self-healing mechanisms of gas-phase and condensed-phase. The high energy density at high temperatures and the superior self-healing capability of alicyclic polyimide further indicate the promise of polyimide dielectric film capacitors for extreme conditions.

The Impact of Gate Annealing on Leakage Current and Radio Frequency Efficiency in AlGaN/GaN High-Electron-Mobility Transistors

Gallium Nitride (GaN) high-electron mobility transistors (HEMTs) are highly promising for high-frequency and high-power applications due to their superior properties, such as a wide energy bandgap and high carrier density. The performance of GaN HEMTs is significantly influenced by the interfacial states of the AlGaN barrier, and gate annealing has emerged as a key process for reducing leakage currents and enhancing DC/RF characteristics. This research investigates the impact of gate annealing on AlGaN/GaN HEMTs, focusing on two main aspects: leakage current reduction and improvements in DC and RF efficiency. Through comprehensive electrical analysis, including DC and RF measurements, the effects of gate annealing were experimentally evaluated. The results show a significant reduction in gate leakage current and noticeable improvements in DC/RF performance for the devices that underwent gate annealing. The study confirms that the annealing process can effectively enhance device performance by modifying the material properties at the gate interface.

Tuning the photocatalytic performance of halide perovskites for efficient solar hydrogen production: A DFT study of CsGeCl3-xXx (X= Br, I)

Photoelectrochemical water splitting holds immense potential for sustainable hydrogen production to address mounting energy demands. However, the development of efficient and cost-effective photocatalysts remains a significant challenge. Perovskites, recognized for their cost-effectiveness and tunable characteristics, show potential as viable candidates in this context. Our investigation is the first to mark the photocatalytic efficacy of CsGeCl3. The findings reveal a modest solar-to-hydrogen (STH) efficiency of 0.74 % due to its wide bandgap energy. Halide mixing with iodine and bromine significantly improves the STH efficiencies, reaching approximately 8.47 %. In addition, applying uniaxial compressive stress further boosts the efficiency to 14.6 %. In this study, we employed the density functional theory (DFT) through the WIEN2k software to scrutinize the structural, electronic, optical, photocatalytic, and thermoelectric properties of all the studied structures. Furthermore, the study evaluated the compounds' capacity for CO2 photoreduction, susceptibility to degradation, and the influence of pH on their photocatalytic performance. The insights gained from this work contribute to the development of efficient and cost-effective perovskite-based photocatalysts for renewable hydrogen production.

RE(HSeO3)(SeO3)(H2O)·(H2O) (RE = Y, Gd): Two Rare-Earth Selenite Nonlinear Optical Crystals with Wide Band Gaps.

The band gap is one of the significant parameters for nonlinear optical (NLO) materials, which is the key factor in their application band in laser technology. This study reports the synthesis of two rare-earth selenite NLO crystals, namely, RE(HSeO3)(SeO3)(H2O)·(H2O) (RE = Y, Gd), utilizing the hydrothermal technique. The two compounds are isostructural, and both belong to the orthorhombic chiral space group of P212121 and possess three-dimensional structures consisting of two-dimensional rare-earth selenite layers connected by hydrogen bonds (O-H··O). These two compounds exhibit a moderate second harmonic generation intensity of 0.5/0.8 × KDP and wide energy band gaps reaching 4.8 eV. Comprehensive density functional theory analyses based on first-principles were carried out to unravel the relationship between the structural and corresponding properties. This work provides an approach for band gap enlargement in rare-earth selenite systems and is beneficial to the design of future NLO materials.

Band gap correction via GGA[formula omitted]mBJ function and strained modulated physical properties of 2D-like DyOBr oxybromide

Two-dimensional (2D) oxyhalides offer unique and fascinating properties due to long-range magnetic ordering in a low dimensional limit. These have potential applications in spintronics and low-dimensional data storage devices. Herein, we demonstrate the biaxial ([110]) strain impact on the electronic and magnetic properties of thermodynamically stable 2D like DyOBr oxybromide based on the first-principles calculations including Hubbard parameter (U) and U+mBJ (modified-Becke-Johnson) methods as well as spin–orbit coupling (SOC) effects. Our calculations predict that an unstrained system exhibits an anti-ferromagnetic (AFM) insulating state with a direct wide energy band gap (Eg) of 5.404 eV within GGA+U+mBJ scheme and the estimated Neel temperature (TN) using the Ising model is 13 K, which is in excellent agreement with the experimentally observed values of 5.41 eV and 9.5 K, respectively. Moreover, it is revealed that Dy ions displayed a large partial spin magnetic moment (ms) of 4.969 μB/f.u. (per formula unit) with S = 2.5 as they lie in ＋ 3 state having the electronic configuration of [fx(x2−3y2)+fy(3x2−y2)]↑2↓1, [fxz2+fyz2]↑2↓1, [fz(x2−y2)]↑1↓0, [fxyz]↑1↓0, and [fz3]↑1↓0. Interestingly, the system displays a large magnetic anisotropy energy of 4.31 meV/atom with a magnetic easy axis of [100] (a-axis), which enhances its utilization in magnetic memory devices. Further, it is established that the AFM insulating behavior of the structure remains robust against biaxial ([110]) strain for the considered range of ±5%. However, a well-ordered shift in conduction band edge (CBE) position to higher and lower energy values is predicted for compressive and tensile strains, respectively. Strikingly, it is found that the TN increases to 265% for ＋5% strain.

Effect of various processing parameters on the properties of ZnO thin films

Zinc oxide (ZnO) thin films are essential in opto-/piezo-electronics due to their transparency, high electron mobility, wide bandgap (∼3.37 eV), and high excitonic binding energy (60 meV). Effects of processing parameters on ZnO thin films, such as the molarity, ageing, thickness, and calcination temperature, on the microstructural and optical properties deposited by sol-gel spin-coating are investigated under one roof. X-ray diffraction (XRD) confirmed the polycrystalline nature of all films, along with a dominant orientation (002) plane, indicating the formation of a c-axis oriented hexagonal wurtzite structure of ZnO regardless of the processing parameters. Peak intensities varied for all samples and exhibited the highest peak intensity annealed at 500 °C, which correlates with the increase in crystallite size from 15.93 to 16.41 nm due to a decrease in defect density via the thermal expansion. 0.4 M aged solution over 70 h showed the variation in the crystallite size and dislocation density, indicating the improvements in the thin film quality. Thickness-dependent ZnO thin films also improved the crystallinity, which was confirmed by high peak intensities. Decreasing the Urbach energy (Eu) of 0.4 M solution indicates reduced lattice imperfections/defects and high electronic quality of thin-film materials. Deposited ZnO films with an ageing time of 70 h and thickness of 109 nm exhibit the highest refractive index of 3.9 and 2.6, indicating light interaction and optimal density. The optimized conditions of sol-gel derived ZnO thin films augment the ease of development of economic devices for practical implications in opto-/piezo-electronics.

Improving photoelectrochemical performance of transferred TiO2 nanotubes onto FTO substrate with Mo2C and NiS as Co-catalyst

The photoelectrochemical (PEC) performance of titanium dioxide nanotube (TiO2 NT) photoelectrodes for sustainable hydrogen production has garnered significant research interest. Despite the advantages of TiO2 NT fabricated via anodization of titanium metal, such as their well-ordered vertical structure, challenges persist including the thick oxide barrier layer, limited optical transparancy, and the wide energy band gap (∼3.0 eV), which constrain their practical efficiency in PEC applications. This study addresses these limitations by introducing a novel approch to transfer TiO2 NT onto a fluorine-doped tin oxide (FTO) substrate. TiO2 NTs were synthesized with varying anodization times and steps to achieve optimal free-standing structures. To further enhance PEC performance, co-catalyst including molybdenum carbide (Mo2C) and nickel sulfide (NiS) were incorporated using immersion and successive ionic layer adsorption reaction (SILAR) methods, respectively. Comprehensive characterization using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultraviolet–visible–near infrared (UV–Vis–NIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) provided insights into the crystal phase, morphological structure, band gap, and elemental composition of the photoelectrodes. Photoelectrochemical and photostability evaluations were conducted through linear scan voltammetry (LSV) and chronoamperometry under dark and light conditions. Results indicate that transferring TiO2 NTs onto FTO significantly enhanced photocurrent density, achieving a 2.5-fold increase at 0.7 V versus a TiO2 NT/Ti substrate. The incorporating of co-catalysts Mo2C, NiS and the combined NiS/Mo2C further enhanced the photocurrent density to 2.20, 3.00 and 8.00 mA cm−2 respectively, with a remarkable 31-fold enhancement compared to the TiO2 NT/Ti substrate. This findings underscore the potential of the TiO₂ NT/FTO photoelectrode with optimized co-catalyst integration for advanced photoelectrochemical applications.

High efficiency in blue TADF OLED using favorable horizontal oriented host

An appropriate host featuring a wide band gap (Eg) and high triplet energy (T1) is crucial for facilitating highly efficient blue-light emitting devices. In this study, 4Ac26CzBz, a new host comprising acridan and carbazole moieties linked to a benzimidazole core, has been synthesized and characterized. Notedly, 4Ac26CzBz exhibits a wide optical gap (Eg) and high triplet energy (T1) of 3.3 and 3.0 eV, respectively, and has been proven a suitable host for blue thermally activated delayed fluorescence (TADF) OLED. By adopting 4TCzBN as a blue-light dopant, a remarkably high device external quantum efficiency of 35.8 % (59.8 cd/A and 62.8 lm/W) and a low turn-on voltage (<3 eV) have been demonstrated, with significant suppression of the efficiency roll-off, maintaining a high efficiency of 29.7 % as luminance at 1000 cd/m2. This excellent performance is deduced from the host’s ambipolar carrier transporting properties, which refer to its ability to transport both electrons and holes effectively, high photoluminescence quantum yield (PLQY) of 98.6 %, and highly horizontal orientation of transition dipole, as determined through diverse analytical measurements. The good material properties of 4Ac26CzBz and the high OLED performance reveal its potential for the next generation’s advanced display and lighting applications.

Enhancement of gaseous toluene removal by photocatalysis using hydrothermal synthesis carbon nanodots/TiO2 combined with zeolite ZSM-5

Abstract Many studies have been conducted to produce composite materials that possess the ability to transform volatile organic compounds (VOCs) to other nontoxic forms economically and environmentally by means of photocatalytic method. However, the main drawbacks of these materials include restricted surface area, low affinity towards organic molecules, and wide band gap energy which dramatically inhibit their performance. In this research, a composite material that surpasses the above disadvantages has been successfully synthesized from TiO2 - carbon nanodots (CDs) - zeolite ZSM-5. Particularly, CDs synthesized by bottom-up method were coated on TiO2 before being uniformly distributed on zeolite ZSM-5. The powder samples with varying CDs/TiO2 and zeolite ZSM-5 content were tested for their photocatalytic oxidization capability to determine the appropriate ratio. The results revealed that samples with higher zeolite content improved photocatalytic activity. Under other survey conditions such as low toluene flowrate, high relative humidity as well as high UV intensity, the photocatalytic performance was enhanced notably. The newly produced material has corrected most disadvantages of traditional photocatalysts, however, further researches need to be made to improve the removal stability.

First demonstration of Sn diffusion into gallium oxide from poly-tetraallyl tin deposited by initiated chemical vapor deposition by thermal treatment

Gallium oxide (Ga2O3) is attracting attention as a next-generation semiconductor material for power device because it has a wide energy band gap and high breakdown electric field. We deposited a Sn polymer, poly-tetraallyl tin, on Ga2O3samples using a disclosed initiated chemical vapor deposition (iCVD) process. The Sn dopant of the Sn polymer layer is injected into the Ga2O3through a heat treatment process. Diffusion model of Sn into the Ga2O3is proposed through secondary ion mass spectroscopy analysis and bond dissociation energy. The fabricated device exhibited typical n-type field-effect transistor (FET) behavior. Ga2O3Sn-doping technology using iCVD will be applied to 3D structures and trench structures in the future, opening up many possibilities in the Ga2O3-based power semiconductor device manufacturing process.

Influence of Hydrothermal Temperature on the Physical Characteristics and Photocatalytics Activity of TiO2 for Degradation of Amoxicillin

Titanium dioxide (TiO2) is a photocatalyst material widely used for environmental remediation applications. In this research, TiO2 material was synthesized using the hydrothermal method at various temperatures (150°C, 180°C, and 200°C). Based on the Fourier-transform infrared (FTIR) data, it was found that all the synthesized materials showed similar absorption peaks, and Ti-O-Ti bonds were detected, which is a characteristic of TiO2. X-ray diffraction (XRD) analysis showed that all the synthesized materials were TiO2 anatase with different crystalline sizes. The synthesized TiO2 using the hydrothermal temperature of 180°C showed the smallest crystalline size of 86.81 nm. Based on the analysis of the band gap energy, it was found that wider band gap energy was obtained at higher hydrothermal temperatures. The band gap energies of the synthesized materials are 3.18 eV, 3.19 eV, and 3.21 eV for hydrothermal temperatures of 150°C, 180°C, and 200°C, respectively. The photocatalytic activity of the three synthesized materials was tested in the photodegradation experiment of amoxicillin under ultraviolet (UV) irradiation. As a result, it was found that TiO2 synthesized at 180°C has the highest photocatalytic activity by degrading 100% of amoxicillin compounds within 120 minutes.

Unveiling capacitive humidity characteristic of CdSe quantum dots synthesized by facile route

Improving the practical uses of a multifunctional humidity sensor requires developing an easy, economical, and environmentally friendly synthesis process. Unfortunately, most humidity sensors have a complicated fabrication process, which drives up their price and restricts their range of applications. In this present work, quantum dots have prevailed as a potential sensing material owing to their small size and large surface area. Herein, we reported the three different colored (green, yellow, and red) based cadmium selenide (CdSe) quantum dots (QDs) using a solution-processed method. Physical characterization of as synthesized CdSe QDs is confirmed using photoluminescence (PL), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV–visible analysis, diffused light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). TEM analysis of CdSe QDs revealed the average particle size of 6 nm. These CdSe QDs were further employed as capacitive humidity sensors. Among the investigated samples, Cd-1 (prepared by 225℃) exhibited the highest sensitivity 93.842 pF/% RH with a rapid response and recovery time of 10 s and 13 s, respectively at 20 Hz. The excellent sensitivity of the Cd-1 is accredited to its least particle size and wider energy band gap as compared to Cd-2 and Cd-3 (prepared by 235 and 245℃) samples. Overall, this work opens an avenue for high performance CdSe QDs based humidity sensors.

Preparation and Application of Co-Doped Zinc Oxide: A Review.

Due to a wide band gap and large exciton binding energy, zinc oxide (ZnO) is currently receiving much attention in various areas, and can be prepared in various forms including nanorods, nanowires, nanoflowers, and so on. The reliability of ZnO produced by a single dopant is unstable, which in turn promotes the development of co-doping techniques. Co-doping is a very promising technique to effectively modulate the optical, electrical, magnetic, and photocatalytic properties of ZnO, as well as the ability to form various structures. In this paper, the important advances in co-doped ZnO nanomaterials are summarized, as well as the preparation of co-doped ZnO nanomaterials by using different methods, including hydrothermal, solvothermal, sol-gel, and acoustic chemistry. In addition, the wide range of applications of co-doped ZnO nanomaterials in photocatalysis, solar cells, gas sensors, and biomedicine are discussed. Finally, the challenges and future prospects in the field of co-doped ZnO nanomaterials are also elucidated.

Modification of morphological, structural and optical properties of graphene oxide by alteration molarity of aqueous KMnO4 solution

This work reports a nontraditional modified Hummer’s method to synthesize graphene oxide (GO) nanosheets by adjusting the oxidation process via a different-molarity potassium permanganate (KMnO4) solution instead of utilizing its powder. The effect of KMnO4 concentrations on the structural and morphological properties of GO nanosheets was studied. Oxidant solutions of 0.5 M, 1 M and 1.5 M were experimented to control the properties of the GO layers. Then, the samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), Raman and ultraviolet-visible (UV–Vis) spectroscopes. Finally, oxidant concentration was optimized at 1 M by which thinner, high-quality crystalline GO layers and wider bandgap energy ( E g ) were obtained. It is thus confirmed that such a modification in the oxidation is a pioneering process to improve the GO properties.

Visible-Light Self-Powered Photodetector with High Sensitivity Based on the Type-II Heterostructure of CdPSe3/MoS2.

Transition metal thiophosphates (MTPs) are a group of emerging van der Waals materials with widely tunable band gaps. In the MTP family, CdPSe3 is demonstrated to possess a wide energy band gap and high carrier mobility, making it a potential candidate in optoelectronic applications. Here, we reported photoelectric response behaviors of both CdPSe3- and CdPSe3/MoS2-based photodetectors (noted as CPS and CM, respectively); these showed prominent photoelectric performances, and the latter proved to be significantly superior to the former. These devices exhibited ultralow dark current at a magnitude order of 10-12 A and fine cycle and air stabilities. Compared with CPS, CM demonstrated the highest responsivity (91.12 mA/W) and detectivity (1.74 × 1011 Jones) at 5 V under 425 nm light illumination. Besides, CM showed self-powered photoelectric responses at zero bias, which was attributed to the improved separation efficiency of photogenerated carriers by the built-in electric field at the interface of the p-n junction. This work proves a prospect for the CM device in portable, self-powered optoelectronic device applications.

Multifunctional Three-in-One Sensor on t-ZnO for Ultraviolet and VOC Sensing for Bioengineering Applications.

Zinc oxide (ZnO) is considered to be one of the most explored and reliable sensing materials for UV detection due to its excellent properties, like a wide band gap and high exciton energy. Our current study on a photodetector based on tetrapodal ZnO (t-ZnO) reported an extremely high UV response of ~9200 for 394 nm UV illumination at 25 °C. The t-ZnO network structure and morphology were investigated using XRD and SEM. The sensor showed a UV/visible ratio of ~12 at 25 °C for 394 nm UV illumination and 443 nm visible illumination. By increasing the temperature, monotonic decreases in response and recovery time were observed. By increasing the bias voltage, the response time was found to decrease while the recovery time was increased. The maximum responsivity shifted to higher wavelengths from 394 nm to 400 nm by increasing the operating temperature from 25 °C to 100 °C. The t-ZnO networks exhibited gas-sensing performances at temperatures above 250 °C, and a maximum response of ~1.35 was recorded at 350 °C with a good repeatability and fast recovery in 16 s for 100 ppm of n-butanol vapor. This study demonstrated that t-ZnO networks are good biosensors that can be used for diverse biomedical applications like the sensing of VOCs (volatile organic compounds) and ultraviolet detection under a wide range of temperatures, and may find new possibilities in biosensing applications.

Photocatalytic Performance of the BaSn-based Nanoscale Materials for the Organic Pollutants Enhanced by Sm (Er) Doping

Background: Sm (Er) doping is an effective strategy for enhancing the photocatalytic activity of the semiconductor photocatalysts for the degradation of organic pollutants. BaSnbased nanorods possess wide band gap energy, which limits the photocatalytic application. It is important to research the feasibility of the improved photocatalytic performance of the BaSnbased nanorods by doping with Sm (Er). Objective: The aim is to synthesize Sm (Er)-doped BaSn-based nanoscale materials through a simple hydrothermal process and research the photocatalytic performance of the Sm (Er)-doped BaSn-based nanoscale materials for the gentian violet degradation. Methods: Sm (Er)-doped BaSn-based nanoscale materials with a polycrystalline structure were synthesized through a simple hydrothermal process. The Sm (Er)-doped composites were analyzed by X-ray diffraction, electron microscopy, solid diffuse reflectance spectrum, X-ray photoelectron spectroscopy, photoluminescence, and electrochemical impedance spectroscopy. Results: Sm (Er) doping induces the morphological evolution of the BaSn-based nanoscale materials from the nanorods to irregular nanoscale particles. Sm (Er) in the doped BaSn-based nanoscale materials exists in the form of the cubic Sm2Sn2O7 and orthorhombic ErF3 phases. The band gap value is decreased with increasing the Sm (Er) dopant contents. Sm (Er)-doped BnSnbased nanoscale materials with the Sm (Er) content of 8wt.% have the lowest band gap and show the strongest light absorption ability. Compared with the un-doped BaSn-based nanoscale materials, the Sm (Er)-doped BnSn-based nanoscale materials exhibit higher photocatalytic activity for the gentian violet degradation. 8wt.% Sm-doped BnSn-based nanoscale materials show the highest photocatalytic activity for the degradation of the gentian violet. 20 mL gentian violet solution (concentration of 10 mg·L-1) can be totally degraded using 20 mg 8wt.% Sm-doped BnSnbased nanoscale materials under UV light illumination for 150 min. Conclusion: The enhanced photocatalytic activity of the Sm (Er)-doped BnSn-based nanoscale materials can be attributed to the decreased band gap, enhanced light absorption ability, and decreased recombination of the photo-generated electron-hole pairs.

Improving the Efficiency and Stability of Perovskite Solar Cells by Refining the Perovskite-Electron Transport Layer Interface and Shielding the Absorber from UV Effects.

This study aims to enhance the performance of perovskite solar cells (PSCs) by optimizing the interface between the perovskite and electron transport layers (ETLs). Additionally, we plan to protect the absorber layer from ultraviolet (UV) degradation using a ternary oxide system comprising SnO2, strontium stannate (SrSnO3), and strontium oxide (SrO). In this structure, the SnO2 layer functions as an electron transport layer, SrSnO3 acts as a layer for UV filtration, and SrO is employed to passivate the interface. SrSnO3 is characterized by its chemical stability, electrical conductivity, extensive wide band gap energy, and efficient absorption of UV radiation, all of which significantly enhance the photostability of PSCs against UV radiation. Furthermore, incorporating SrSnO3 into the ETL improves its electronic properties, potentially raising the energy level and improving alignment, thereby enhancing the electron transfer from the perovskite layer to the external circuit. Integrating SrO at the interface between the ETL and perovskite layer reduces interface defects, thereby reducing charge recombination and improving electron transfer. This improvement results in higher solar cell efficiency, reduced hysteresis, and extended device longevity. The benefits of this method are evident in the observed improvements: a noticeable increase in open-circuit voltage (Voc) from 1.12 to 1.16 V, an enhancement in the fill factor from 79.4 to 82.66%, a rise in the short-circuit current density (Jsc) from 24.5 to 24.9 mA/cm2 and notably, a marked improvement in the power conversion efficiency (PCE) of PSCs, from 21.79 to 24.06%. Notably, the treated PSCs showed only a slight decline in PCE, reducing from 24.15 to 22.50% over nearly 2000 h. In contrast, untreated SnO2 perovskite devices experienced a greater decline, with efficiency decreasing from 21.79 to 17.83% in just 580 h.

In situ preparation, structures, photoluminescence and semiconductor properties of two novel cadmium compounds

Two novel cadmium compounds (me2-4,4'-H2bipy)9[(CdCl3)-HCl-(CdCl3)](CdCl3)4(CdCl4)6 (1) and (me2-4,4'-H2bipy)9[(CdCl3)-HCl-(CdCl3)]3[CdCl4(H2O)]6 (2) (me = methyl; 4,4'-bipy = 4,4'-bipyridine) have been synthesized through solvothermal reactions and their crystal structures were determined by single-crystal X-ray diffraction technique. The me2-4,4'-H2bipy moiety was obtained via in situ reactions. The single-crystal X-ray diffraction analyses revealed that both compounds are crystallized in the P 3 ( – ) 1 c space group of the hexagonal system and both are characterized by a 0-D isolated structure. Powder photoluminescent characterization reveals that compounds 1 and 2 show an emission in the blue or red region of the spectrum. Compounds 1 and 2 possess wide energy band gaps of 3.49 and 5.01 eV as found by the solid-state UV/Vis diffuse reflectance spectrum.

Cu2+ and W6+ co-doped Na0·5Bi0·5TiO3 solid solution: An effective approach to inhibit oxygen vacancy generation and suppress oxygen ion conduction

Thanks to its outstanding features, the Na0·5Bi0·5TiO3 is a promising as a dielectric material for various advanced electronic devices. However, its high oxygen ionic conductivity and wide band-gap energy pose limitations on its suitability for commercial applications. In this work, an approach to inhibit oxygen vacancy generation and suppress oxygen ion conduction is investigated through the B-site donor and acceptor doping strategy. This study aims to investigate the morphological, structural, compositional, dielectric, electric, and optical properties of 0.99NBT-0.01BCW and 0.985NBT-0.015BCW perovskite ceramics. The research also explores the impact of Cu2+ and W6+ substitution on the perovskite structure and its potential applications. Morphological analysis revealed well-defined grains with cubic shapes, influenced by Cu2+ and W6+ incorporation. Structural analysis confirmed a rhombohedral lattice with R3c space group. Dielectric analysis showed ferroelectric to antiferroelectric and antiferroelectric to paraelectric phase transitions, with emphasis on relaxor behavior influenced by BCW doping. Electric analysis demonstrated a semiconductor behavior with activation energies, suggesting inhibited conduction loss at high temperatures due to BCW doping. Optical analysis revealed direct bandgap energies suitable for applications in optoelectronics and photonics. These findings suggest that doping with Cu2+ and W6+ restrains conduction losses at elevated temperatures, potentially serving as the primary mechanism for suppressing the high-temperature dielectric loss in NBT-based ceramics. They highlight the potential of these perovskite ceramics in applications such as capacitors, sensors, and optoelectronic devices.