Doping Concentration Research Articles

Tailoring Sb-F doped ZnO nanoparticles for dual-functionality: Photocatalytic and supercapacitor applications

In the present work, pure zinc oxide nanoparticles (ZnO NPs), antimony doped ZnO nanoparticles (Sb-ZnO NPs), fluorine doped ZnO nanoparticles (F-ZnO NPs), and antimony and fluorine co-doped ZnO nanoparticles (Sb/F-ZnO NPs) with various dopant concentrations are synthesized by co-precipitation method. The optical, structural, morphological, photocatalytic, and electrochemical activities of ZnO nanostructures by the influence of Sb and F doping were investigated. XRD showed crystallite size decreased with increasing Sb/F content, while BET showed 64.25 m2/g surface area for ZnO-5 %Sb-10 %F. SEM and TEM images suggesting Sb/F doping changed the ZnO morphology from spherical to bricks-built and nanorod-built flower structures. XPS verified Sb (+3) and F (−1) oxidation states, while absorption spectroscopy showed increased energy bandgap with 5 % Sb and 10 % F doping in ZnO. The photocatalytic activity for mixture of congo red, rhodamine B, and methylene blue are closer to real polluted water. All the samples exhibited good photocatalytic activity for the methylene blue with degradation efficiency reaching to 99 %. At a constant current density of 1 A/g, symmetric supercapacitors utilizing Sb/F-ZnO electrodes exhibited a specific capacitance of 762 Fg−1, underscoring their superior electrochemical performance and potential for advancing energy storage technologies. Further, physiochemical and electrochemical properties of ZnO can be perfectly tuned by the optimal setting for co-doping in ZnO up to 5 % Sb and 10 % F by the co-precipitation approach.

Spectroscopic analysis of La2(WO4)3:Tb3+ phosphor and the delayed concentration quenching of 5D4 →7FJ emission

Trivalent terbium ion doped lanthanum tungstate (La2-xTbx(WO4)3; x = 0.6,1.0,1.4) and terbium tungstate (Tb2(WO4)3) phosphors were successfully synthesized via optimized microwave-assisted co-precipitation technique. The phase purity and crystallinity of the prepared samples were confirmed using the powder XRD technique. The photoluminescence studies revealed a quenching-free emission up to 70 % of Tb3+ doping concentration, even though the emission intensity slightly decreases under host excitation since it becomes less relevant at higher doping concentrations. The experimental and calculated oscillator strengths were evaluated using absorption data and further used to quantify the Judd - Ofelt (JO) intensity parameters, which appeared in a trend of Ω2>Ω4>Ω6 for all samples. As a theoretical approach to assure the excellency of the tungstate host, the radiative parameters were calculated from the emission data using the JO analysis technique. The dominance in the values of stimulated emission cross section and gain bandwidth corresponding to 5D4→7F5 transition of Tb3+ ion of lanthanum tungstate proclaims it as an excellent green phosphor. Hence, the less susceptibility of the tungstate host towards concentration quenching is confirmed in the present work.

Al concentration-dependent electrical modulation of Al-doped ZnO thin film using atomic layer deposition

A series of 150-nm-thick Al-doped ZnO (AZO) thin films with various Al doping concentrations were deposited by atomic layer deposition technique to determine their applicability in transparent electronic devices. For incorporation into transparent electrodes, the electrical properties of AZO films must be modulated to minimize the parasitic effect. The results show that AZO thin films with various Al dopant concentrations had different work-functions and electrical contact properties, while the other physical characteristics were not significantly changed. Hence, AZO thin films can be used as transparent conducting oxide materials and are potential alternatives for the currently used indium-tin-oxide (ITO) thin films.

Excellent thermoelectric performance in alkali metal phosphides M3P (M = Na and K) with phonon-glass electron-crystal like behaviour.

Identifying ideal thermoelectric materials presents a formidable challenge due to the intricate coupling relationship between thermal conductivity and power factor. Here, based on first-principles calculations, along with self-consistent phonon theory and the Boltzmann transport equation, we theoretically investigate the thermoelectric properties of alkali metal phosphides M3P (M = Na and K). The evident 'avoided crossing' phenomenon indicates the phonon glass behavior of M3P (M = Na and K). Due to the strong lattice anharmonicity induced by alkali metal elements, accounting for quartic anharmonic corrections, the lattice thermal conductivities of Na3P and K3P at room temperature are merely 0.25 and 0.12 W m-1 K-1, respectively. Furthermore, the high degeneracy and 'pudding-mold-type' band structure lead to high p-type PF in M3P (M = Na and K). At 300 K, the p-type power factors (PF) of Na3P and K3P can reach 3.90 and 0.80 mW mK-2, respectively. The combination of ultralow κL and high PF leads to excellent thermoelectric figure of merit (ZT) values of 1.70 (3.38) and 1.18 (2.13) for p-type Na3P and K3P under optimal doping concentration at 300 K (500 K), respectively, surpassing traditional thermoelectric materials. These findings demonstrate that M3P (M = Na and K) exhibits behavior similar to phonon-glass electron crystals, thereby indicating a direction for the search for high-performance thermoelectric materials.

Photoluminescence and scintillation properties of rare earth doped Lu2O3 single crystal grown by floating zone method

A series of Lu2O3 single crystals doped with rare earth (RE) ions (RE = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb, dopant concentrations are 1 %) was synthesized by the floating zone method. Their photoluminescence (PL) and scintillation properties were evaluated. In PL, emissions due to 4f-4f transitions of trivalent rare earth ions were observed, and those doped with Nd3+, Eu3+, Tb3+ and Er3+ showed the highest emission intensities among the samples. As a scintillation property, those doped with Eu, Gd, and Dy showed a clear photoabsorption peak under 137Cs 662 keV γ-ray irradiation. Among them, the Eu3+-doped Lu2O3 showed the highest scintillation light yield of 67000 photons/MeV. The current work conducted the first systematic study of rare earth doped Lu2O3 single crystals grown by the floating zone method.

Synthesis, characterization and effective UV photo-sensing properties of Ga3+ doped NiO nanoparticles

In this work, resistive type photodetectors were fabricated using Gd3+ ions doped NiO nanoparticles to improve the detection of ultraviolet (UV) light. The occurrence of the simple cubic phase in NiO systems has been shown by X-ray diffraction patterns. The crystalline size of the NiO nanoparticles doped with different concentrations of Gd3+ at levels of pure, 1 %, 2 %, and 3 % were 6 nm, 8 nm, 9 nm, and 12 nm, respectively. The presence of dopants in the material was established by the Raman spectrum analysis. Transmission electron microscopy (TEM) pictures were used to validate the morphological properties of Gd3+ doped NiO nanoparticles nanoparticles at different degrees of dopant concentration (0 %, 1 %, 2 % and 3 %). The introduction and concentration of dopants alter the shape of NiO material. Based on the findings of UV–visible absorption spectroscopic studies, it can be concluded that the addition of Gd3+ ions to the system improved the absorption characteristics. The measured bandgap values for various degrees of Gd3+ doping, namely 0 %, 1 %, 2 %, and 3 %, are 3.51 eV, 3.45 eV, 3.36 eV, and 3.23 eV, respectively. According to the measured photoluminescence spectrum, Gd3+ ions may efficiently trap and maintain excited electrons within an energy level between the ground and excited states. This process greatly extends the lifespan of excitons from immediate recombination. The use of Gd3+-doped NiO sensors in UV photodetection resulted in a significant increase in conductivity and photocurrent. The photodetector fabricated using a 3 % concentration of Gd3+ doped NiO, has a responsivity of 24 × 10−2 AW−1, a detectivity of 14 × 109 Jones, and an external quantum efficiency (EQE) of 62 %.

Superior photocatalytic degradation of pharmaceuticals and antimicrobial Features of iron-doped zinc oxide sub-microparticles synthesized via laser-assisted chemical bath technique

Addressing the dual challenges of antimicrobial resistance and pharmaceutical contamination in wastewater is crucial for global health and environmental preservation. Predictions estimate up to 10 million annual deaths by 2050 due to antimicrobial resistance, underscoring the urgent need for innovative solutions. This study explores the potential of zinc oxide Sub-Microparticles (ZnO SMPs) doped with iron (Fe) to enhance the photocatalytic degradation of pharmaceutical compounds in water and improve antimicrobial efficacy. A green laser-assisted chemical bath synthesis method created ZnO SMPs with varying Fe dopant concentrations (1 %, 1.5 %, and 3 %). The synthesized Sub-Microparticles underwent rigorous structural analysis using X-ray diffractometry, SEM, EDX, FTIR, and UV–visible spectrophotometry techniques. Their photocatalytic performance was evaluated in the degradation of paracetamol under blue laser light, and their antimicrobial properties were assessed following CLSI guidelines. Structural analyses confirmed the hexagonal wurtzite structure of ZnO SMPs, with noticeable changes due to Fe doping, including a transition from sub-microrods to sub-microsheets and a redshift in the optical band gap. Photocatalytic tests revealed a significant enhancement in paracetamol degradation efficiency, increasing from 53.41 % with pure ZnO to 98.99 % with 3 % Fe-doped ZnO in 50 min. Antimicrobial assays demonstrated an increased inhibitory effect against pathogens, with Fe-doped ZnO outperforming control discs. This study substantiates the potential of Fe-doped ZnO SMPs in wastewater treatment and antimicrobial applications, showcasing significant improvements in photocatalytic degradation of pharmaceutical compounds and antimicrobial efficacy. The findings underscore the importance of continuing research in this domain for environmental and public health benefits.

Novel Orange-Emitting YPO4:Sm3+/Polymer Nanocomposite Phosphor Films for LED Applications.

A polymer based nanocomposite (NC) material embedded with highly luminescent nanopowders could be promising for replacing traditional luminescent materials from a technological pointof view.In this study, we have successfully obtained YPO4: Sm3+ /Polymer nanocomposite phosphor films by embedding YPO4: Sm3+ luminescent nanoparticles (NPs) for orange-light emitting diode (LED) applications. These luminescent NPs were synthesized using the sol gel method in different polymer matrices i.e. polystyrene (PS) and poly (methyl methacrylate) (PMMA) by using direct solution mixing. The structural, morphological, and photoluminescence characteristics of the nano-phosphors and resulting NC films were examined and discussed. The emission spectra of YPO4: Sm3+ (x at.%) nano-phosphors under near-UV excitation at 404nm were dominated by orange emission attributed to 6H5/2 4F7/2 (601nm) luminescence of Sm3+ ions. The optimum doping concentration of activator Sm3+ in YPO4 matrix was found to be 5 at.%. When the doping concentration of Sm3+ was higher than 5 at.%, concentration quenching occurred. The incorporation of YPO4: Sm3+ NPs into polymer matrices indicated that the NCs retained the original luminescence properties of the luminescent NPs, although a decrease in their emission intensity was observed for the NC films, attributable to a polymer matrix effect, which dominated in PS matrix. The fluorescence decay times of NPs in the NC films were measured and compared to those of proper YPO4: Sm3+ nano-phosphors. A decrease in decay time in NC film was observed due the effective refractive index effect. Temperature-dependent photoluminescence (TDPL) of PMMA NC film was studied in 100-400K range, investigating the thermal stability of the film. Additionally, CIE coordinates confirmed the red-orange light emission of the prepared phosphors and NC films. The obtained results indicate that the synthesized polymer-nanophosphor NC films are promising candidates for orange-LED applications.

Construction of Concentration Quenching‐Resistant Multi‐Resonance TADF Emitters via Positional Isomerization for OLEDs

AbstractMultiple resonance thermally activated delayed fluorescence (MR‐TADF) emitters are promising for high‐definition organic light‐emitting diodes (OLEDs) due to their high exciton utilization and color purity. However, strong interchromophore interactions cause most MR‐TADF emitters with planar structures to aggregate at high doping concentrations, leading to degraded efficiencies. Herein, using benzenesulfonyl‐functionalized dibenzothiophene sulfoximine with steric effects, three MR‐TADF emitters (2SBN, 3SBN, and 4SBN) are synthesized by coupling the classic DtBuCzB skeleton at different sites. Three emitters exhibit green or blue‐green emission with full width at half maximum (FWHM) values less than 29 nm and photoluminescence quantum yields exceeding 90%. OLEDs based on 2SBN, 3SBN, and 4SBN achieve high maximum external quantum efficiency (EQEmax) values of 30.1%, 27%, and 33.8%, respectively, at a 5 wt.% doping concentration. Notably, due to the distorted conformation of 4SBN and suppressed intermolecular interaction, the OLED remains high EQEmax of 28.9% at a doping concentration of 20 wt.%. These results demonstrate the feasibility of molecular design to modulate spatial conformations via positional isomerism to develop MR‐TADF emitters with reduced concentration quenching.

Correlating Cu dopant concentration, optoelectronic properties, and photocatalytic activity of ZnO nanostructures: experimental and theoretical insights

The photocatalytic activity of photocatalysts can be enhanced by cation doping, and the dopant concentration plays a key role in achieving high efficiency. This study explores the impact of copper (Cu) doping at concentrations ranging from 0% to 10% on the microstructural, optical, electronic, and photocatalytic properties of zinc oxide (ZnO) nanostructures. The x-ray diffraction analysis shows a non-linear alteration in the lattice parameters with increasing the Cu content and the formation of CuO as a secondary phase at the Cu concentration of >3%. Density functional theory calculations provide insights into the change in the electronic structures of ZnO induced by Cu doping, leading to the formation of localizeddelectronic levels above the valence band maximum. The modulation of the electronic structure of ZnO by Cu doping facilitates the visible light absorption via O 2p → Cu 3d and Cu 3d → Zn 2p transitions. Photoluminescence spectroscopy reveals a quenching of the defect-related emission peak at approximately 570 nm for all Cu-doped ZnO nanostructures, indicating a reduction in the structural and other defects. The photocatalytic activity tests confirm that the ZnO nanostructures doped with 3% Cu exhibit the highest efficiency compared to other samples due to the suitable band-edge position and visible light absorption.

ZnO thin films co-doped with III-valence metals and halogens: theory and experiment

The efficiency of metal-halogen co-doping of ZnO thin films deposited by DC magnetron sputtering of ceramic targets has been studied theoretically and experimentally. The influence of deposition temperature (300 − 900 K range), ZnX2 pressure (10−10−1 atm), Me2O3 dopant concentration (10−3 − 10 mol %), and Zn pressure (10−14 − 10−6 atm) on the composition of ZnO − Me2O3 − ZnX2 − Zn (Me = Al, Ga, In; X = F, Cl, Br, I) systems has been analyzed theoretically. The surface migration velocity of oxides and halides is also estimated for a wide temperature range. According to the calculation results, the optimal deposition conditions have been recommended. ZnO thin films co-doped with Al+Cl, Ga+Cl, Ga+Br, Ga+I, and In+Cl were deposited using ZnO:Me:X ceramic targets sintered by chemical vapor transport based on halides. The influence of the stoichiometric deviation of ceramic targets, the concentration of halogens, and metal impurities on thin films’ electrical, structural, compositional, and optical properties has been investigated. It is shown that Ga+Cl+Zn co-doping is the most promising. This co-doping increases both the structural perfection of films (electron mobility) and doping efficiency by Ga (charge carrier concentration), reducing the resistivity of thin films by two times compared to the use of classical ZnO:Ga ceramic targets. The optimal stoichiometric deviation of ZnO:Me:X ceramics targets, corresponding to the highest electron mobility and figure of merit of thin films, has been recommended.

Suppression of efficiency roll-off in solution-processed OLEDs using pyrimidine-based iridium complexes modified with sterically hindered groups

Three bis-cyclometalated iridium complexes Ir1-Ir3 were successfully synthesized through mild reaction conditions. All complexes exhibit emission peaks at 507-509 nm, with excellent photoluminescence quantum efficiencies (PLQY) ranging from 69% to 97%. Self-quenching is significantly reduced because the steric spacers lead to minimum bimolecular interactions. Accordingly, the electroluminescence device based on complex Ir3 exhibits a maximum luminous efficiency of 39.6 cd A−1, a high EQE of 13.1% with an efficiency roll-off of 4.2% at 1000 cd m−2, which is much smaller than that (10.8%) of the Ir1-based device. Moreover, its devices exhibit excellent stability even at elevated doping concentrations, suggesting a notable reduction in intermolecular interactions caused by the steric pinene spacer.

Switching figure-of-merit, optimal design, and power loss limit of (ultra-) wide bandgap power devices: A perspective

Power semiconductor devices are utilized as solid-state switches in power electronics systems, and their overarching design target is to minimize the conduction and switching losses. However, the unipolar figure-of-merit (FOM) commonly used for power device optimization does not directly capture the switching loss. In this Perspective paper, we explore three interdependent open questions for unipolar power devices based on a variety of wide bandgap (WBG) and ultra-wide bandgap (UWBG) materials: (1) What is the appropriate switching FOM for device benchmarking and optimization? (2) What is the optimal drift layer design for the total loss minimization? (3) How does the device power loss compare between WBG and UWBG materials? This paper starts from an overview of switching FOMs proposed in the literature. We then dive into the drift region optimization in 1D vertical devices based on a hard-switching FOM. The punch-through design is found to be optimal for minimizing the hard-switching FOM, with reduced doping concentration and thickness compared to the conventional designs optimized for static FOM. Moreover, we analyze the minimal power loss density for target voltage and frequency, which provides an essential reference for developing device- and package-level thermal management. Overall, this paper underscores the importance of considering switching performance early in power device optimization and emphasizes the inevitable higher density of power loss in WBG and UWBG devices despite their superior performance. Knowledge gaps and research opportunities in the relevant field are also discussed.

Numerical analysis of hybrid perovskite solar cells with NiOx and TiO2 as the charge transport layer

ABSTRACT This work exposits a hybrid perovskite-based solar cell consisting of NiOx as an electron-blocking material and TiO2 as a hole-blocking material to enhance its performance. Because the EBL material is critical to increasing efficiency and stability in a perovskite-based photovoltaic device, NiOx is being taken as a blocking material for improved reliability. It is also cost-effective and shows less hysteresis in contrast with alternative EBL materials. In addition, a wide band gap material like TiO2 as HBL is considered for enhancing carrier transportation phenomena that improve device performance. The efficiency of the suggested photovoltaic device is assessed in terms of solar parameters using the TCAD numerical simulation tool, accounting for the impacts of the thickness of the perovskite material, the density of defects, and the blocking material doping concentration. Also, the temperature reliability study is thoroughly investigated, considering all the optimised thicknesses of different layers and their optimised doping level.

Rare earth Nd3+-doped organic-inorganic hybrid perovskite quantum dots for white LED

Lead halide perovskite quantum dots (QDs) have garnered significant attention due to their tunable band gaps, unique quantum confinement effects, and high photoluminescence quantum yields (PLQYs). Among them, Organic-inorganic QDs make them promising candidates for optoelectronic devices such as quantum dot light-emitting diodes (QLEDs), solar cells, lasers, and photodetectors. However, the toxicity of lead (Pb) has raised environmental and health concerns, hindering their industrial application. To alleviate concerns about heavy metals Pb, extensive research has been conducted on B-site doping and the development of lead-free perovskites. Herein, we firstly developed B-site doping strategy on organic-inorganic hybrid perovskite QDs via rare-earth elements. Neodymium (III) (Nd3+) doped FAPbBr3 QDs were prepared through the ligand-assisted reprecipitation method at room temperature. The B-site doping strategy could alleviate the heavy metal problem of Pb and modulate the band gap of FAPbBr3 QDs facilely. The results demonstrated that increasing the concentration of Nd³⁺ can change the emission of FAPbBr₃ QDs from pure green to deep blue. Specifically, we achieved highly pure blue emission (∼438 nm) with a full width at half maximum (FWHM) of 13 nm for Nd³⁺-doped FAPbBr₃ QDs. Time-resolved photoluminescence (TRPL) spectroscopy revealed a decrease in the lifetime of FAPbBr₃ QDs from 22.86 to 15.46 ns as the doping concentration increased. Additionally, we fabricated a white LED (WLED) utilizing blue-emitting Nd³⁺-doped FAPbBr₃, green-emitting FAPbBr₃ QDs, and red QDs, achieving a white emission color coordinate of (0.33, 0.36). This study pioneers the application of B-site rare-earth doping in organic-inorganic hybrid perovskite QDs, demonstrating that B-site composition engineering is a reliable strategy to further exploit the perovskite family for wider optoelectronic applications.

Influence of Mo doping on the structural, Raman scattering, and magnetic properties of NiO nanostructures

In this work, the Ni1-xMoxO, (x = 0.000, 0.025, 0.050, 0.075, 0.100, and 0.150) nanoparticles were prepared employing the coprecipitation method. The X-ray diffraction (XRD) confirmed that all the samples have a face-centered cubic (FCC) structure with no secondary phases by the effect of the Mo-doping. The Mo-dopants yielded smaller crystallites, reaching a size of 9 nm with x = 0.150. The transmission electron microscope (TEM) images revealed agglomerated NiO nanoparticles with nearly spherical shapes varied to elliptical-like shapes upon increasing Mo concentration. The energy dispersive X-ray (EDX) confirmed the purity of the synthesized samples. The XPS analysis confirmed the valence states of the presented elements in the samples as Ni2+, Ni3+, Mo6+, and O2− ions. The XPS detected the reduction of the nickel and oxygen vacancies, by studying the ratio of Ni2+/Ni3+ and lattice oxygen (OL) to vacant oxygen (OV) peaks. The Raman analysis demonstrated the active vibrational modes of NiO, for all the samples, along with stretching Mo = O bonds for the doped samples. The Photoluminescence (PL) spectroscopy was employed to study the near band edge and deep level emissions, giving insight to the defect levels within the band gap. The PL affirmed the decrease of the oxygen vacancies upon Mo-doping. Besides, the magnetic hysteresis measurements at room temperature revealed the superparamagnetic contribution embedded in the antiferromagnetic matrix of NiO. The magnetization was tuned by Mo doping concentration, where it affected the saturation magnetization, coercivity, and remnant magnetization. Mo dopant can modify the magnetic property of NiO nanoparticles and can be a potential candidate in biomedical field and data storage applications.Graphical

Ce Doping Effects on the Hydrogen Sensing Properties of Graphene/SnO2-Based Sensors.

The development of a sensor capable of selectively detecting hydrogen levels in the environment holds immense importance for ensuring the safer utilization of hydrogen energy. In this study, a hydrogen sensor made of Ce-doped single-layer graphene (SLG)/SnO2 composite material was fabricated using a hydrothermal method. The study examined the impact of varying Ce doping concentrations on the hydrogen sensing capabilities of the SLG/SnO2 matrix. The results show that the SLG/SnO2 hydrogen sensor doped with 2 mol% Ce demonstrated optimal performance at a humidity of 20%. It operated most efficiently at 250 °C, with a response of 2.49, representing a 25.75% improvement over the undoped sample. The response/recovery times were 0.46/3.92 s, which are 54.9% shorter than those of the undoped sample. The enhancement in hydrogen sensitivity stems from the synergistic effect of Ce and SLG, which facilitates the coexistence of n-n and p-n heterojunctions, thereby increasing carrier mobility and refining grain structure. Analysis via X-ray photoelectron spectroscopy (XPS) reveals that Ce increases the material's oxygen vacancy concentration, enhancing its hydrogen sensitivity. Ce-doped SLG/SnO2, with its robust hydrogen sensitivity, represents one of the leading candidates for future hydrogen gas sensors.

Polarized Upconversion of sub-100 nm Single Nanoparticles.

Upconversion nanoparticles are popular as imaging probes due to their advantages in photostability and controllable emission dimensions. However, upconversion polarization remains largely uncharted with previous reports limited to microstructures. In this work, we report the observation of polarized upconversion emissions from β-NaYF4 single nanostructures below 100 nm. At the sub-100 nm scale, nanorods, nanodiscs, and nanoplates exhibit distinctive polarization degrees despite the same doping concentrations of lanthanides. We find this varied polarization degree results from the crystallographic orientation of nanostructure in relation to the light field and can be linked to the distinctive emission spectrum profile with varied Stark splitting transition ratios from Er3+. Our findings provide a comprehensive understanding of the polarization properties of upconversion nanoparticles, revealing a previously unexplored aspect of light emission. This discovery expands our knowledge of upconversion nanoparticles and also opens new possibilities for their use in future imaging and sensing applications, where polarization sensitivity is crucial.

The influence of the dopant concentration and sintering parameters on properties of antimony doped barium stannate ceramics

In this paper, the influence of antimony concentration and different sintering techniques on the structural, microstructural, and electrical properties of antimony-doped barium stannate, BaSn1-xSbxO3 (BSSO, x = 0.00, 0.04, 0.06, 0.08 and 0.10) was investigated. BSSO-based ceramic samples were obtained by conventional and spark plasma sintering. The XRD analysis confirmed the single-phase, cubic BaSnO3 lattice system in all conventionally sintered samples. Apart from the dominant cubic phase, the spark plasma sintering conditions led to the formation of a secondary phase, Ba2SnO4, in all samples. FESEM analysis revealed the presence of low angle grain boundaries (LAGBs) in BSSO samples with high antimony concentration (x = 0.08), independently of the sintering technique. However, the fraction of LAGBs is significantly higher in the BaSn0.92Sb0.08O3-SPS sample due to the simultaneous exposure of the conductive sample to the effects of high temperature and pressure during sintering process. These boundaries have low activation energy and allow free charge carrier transport through the grain boundary region. The high dopant concentration and the presence of large fraction of LAGBs in BaSn0.92Sb0.08O3-SPS sample reflected on its electrical properties through low and almost temperature-independent electrical resistivity in the temperature range of 25–150 °C.

Highly saturated red-emitting novel europium doped yttrium calcium borate (Eu3+: Y2CaB10O19) phosphor materials for eco-friendly solid-state lighting applications

Optical parameters like low correlated color temperature (CCT), color rendering index (CRI), color purity, thermal stability and etc. are crucial parameters for the practical applications of white light emitting diode applications. High color purity around 100 % red emitting novel europium doped yttrium calcium borate (Eu3+: Y2CaB10O19) phosphors were harvested by conventional solid-state synthesis technique. The novel host material possesses monoclinic crystal structure with no observable shift in the diffraction lines with varying dopant concentrations. FTIR studies revealed the presence of BO3 and BO4 networks in the host lattice responsible for structural rigidity and good thermal stability. The phosphor materials synthesized xEu3+: Y2CaB10O19 (x = 0.01, 0.03, 0.05, 0.07 and 0.09), are sensitive to both 250 nm (UV) and 393 nm (Near UV/blue LED) for excitation that can produce deep orange (594 nm) emission along with red emission (612 nm). The optimum Eu3+ ion concentration was fixed at 5 mol% of dopant ions to prevent the concentration quenching. As prepared optimal phosphor material possesses high color purity around 100 %, CCT of 1214 K defines its applicability in WLED applications. The synthesized phosphor materials pertain excellent switching response, thermal stability and the fabricated P-i-G possesses desired photometric parameters for its practical applications.