Increase In Doping Concentration Research Articles

Study on the electrochemical effect of ZnO addition on flash sintering of 3 mol% yttria stabilized zirconia

Flash Sintering has shown tremendous promise in reducing the sintering time and temperature. However, significant heterogeneity in densification and microstructure was observed in the flash-sintered sample due to hotspot formation and electrochemical effects (electrochemical blackening). In this work, we have varied the extent of electrochemical reaction by (0.75-3 mol%) ZnO addition during flash sintering of 3 mol% yttria-stabilized Zirconia (3YSZ). A substantial increase in grain size was observed throughout with an increase in dopant concentration. With the addition of 0.75 mol% ZnO dopant in 3YSZ, a significant improvement in densification and a significant reduction in the presence of cracks were observed. The extent of electrochemical blackening was seen to be increasing with the increase in dopant concentration. The blackened phase was found to be distorted tetragonal Zirconia by Raman analysis. The ZnO doped 3YSZ showed ionic to electronic transition in conduction during flash sintering likely due to electrochemical effects.

Synthesis of yttrium doped zinc oxide nanorods for display, forensic and supercapacitor applications

Yttrium (1–7 mol %) doped Zinc Oxide (ZnO) nanoparticles (NPs) are synthesized by hydrothermal method followed by calcination. The synthesized NPs are characterized by different techniques. The Bragg reflections confirm the formation of a hexagonal wurtzite crystal structure. The crystallite size is estimated by both Scherrer’s and Williamson’s-Hall plot methods. The surface morphology is decorated with nanorods of different sizes with sharp edges. As the dopant concentration increases changes in their alignment were also observed. The direct energy band gap determined from Wood and Tauc’s relation was found to be increased from 3.183 to 3.197 eV with an increase in the dopant concentration. The photoluminescence emission spectra excited under 344 nm shows less intensity peaks in the blue and green region whereas the high-intensity peaks are observed in the red region. The concentration quenching is observed at 5 mol % yttrium concentration. This concentration quenching is caused due to dipole–dipole interaction. Further, the Commission Internationale de I’Eclairage (CIE) coordinates fall in a purplish-red region. The average Color Correlated Temperature (CCT) value of 3595 K clearly indicates that the present synthesized NPs might find an application in warm display technology as a nano phosphor material. For oxidation and redox peaks, cyclic voltammetry analysis is also carried out. Ion transport kinetics were disclosed by Electrochemical impedance spectroscopy (EIS), and super capacitance values were acquired using Galvanostatic Charge Discharge (GCD) analysis. For ZnO:Y (1–7 mol %) NPs, specific capacitance values were discovered to be in the range of 33 to 74 F/g with a change in dopant concentration. Therefore, the currently synthesized material may find use in both energy storage materials and the field of display technology and latent fingerprints (LFPs).

Multiphysics Modeling and Analysis of Sc-Doped AlN Thin Film Based Piezoelectric Micromachined Ultrasonic Transducer by Finite Element Method.

This paper presents a Piezoelectric micromechanical ultrasonic transducer (PMUT) based on a Pt/ScAlN/Mo/SiO2/Si/SiO2/Si multilayer structure with a circular suspension film of scandium doped aluminum nitride (ScAlN). Multiphysics modeling using the finite element method and analysis of the effect of different Sc doping concentrations on the resonant frequency, the effective electromechanical coupling coefficient (keff2) and the station sensitivity of the PMUT cell are performed. The calculation results show that the resonant frequency of the ScAlN-based PMUT can be above 20 MHz and its keff2 monotonically rise with the increasing doping concentrations in ScAlN. In comparison to the pure AlN thin film-based PMUT, the static receiving sensitivity of the PMUT based on ScAlN thin film with 35% Sc doping concentration is up to 1.61 mV/kPa. Meanwhile, the static transmitting sensitivity of the PMUT is improved by 152.95 pm/V. Furthermore, the relative pulse-echo sensitivity level of the 2 × 2 PMUT array based on the Sc doping concentration of 35% AlN film is improved by 16 dB compared with that of the cell with the same Sc concentration. The investigation results demonstrate that the performance of PMUT on the proposed structure can be tunable and enhanced by a reasonable choice of the Sc doping concentration in ScAlN films and structure optimization, which provides important guidelines for the design of PMUT for practical applications.

Enhancing antimicrobial and photocatalyst properties of Mg-doped ZnO nanotubes via novel laser-assisted chemical bath synthesis

Laser-Assisted Chemical Bath Synthesis (LACBS) was used to fabricate pure and magnesium-doped zinc oxide nanoparticles. Analysis of these nanoparticles' structural, morphological, optical, and antimicrobial characteristics was conducted. This analysis spanned across varying concentrations of magnesium-doped zinc oxide from 1 % to 3 %. XRD confirmed the nanoparticles' crystalline nature, revealing the hexagonal wurtzite phase. SEM analysis showcased their nanometric domain existence and hexagonal crystalline morphology, transforming from nanorods to nanotubes. Optical analysis showed band gap energy decrease from 3.27 to 2.85 eV correlating with the magnesium doping concentration increase. Optical absorption displayed a distinctive redshift for the nanoparticles as magnesium concentration increased from 1 % to 3 %. Photocatalytic assessments highlighted the superior degradation ability of 3 % Mg-doped nanoparticles, showing a 98.04 % degradation rate against methylene orange dye under blue light exposure. Antimicrobial activity tests against various pathogens showed that Mg ions' incorporation significantly enhanced antimicrobial performance, demonstrating the effectiveness of the LACBS method.

(K0.5Bi0.5)(Mg1/3Nb2/3)O3‐modified Sr0.7Bi0.2TiO3 lead‐free ceramics for energy storage applications

AbstractIn the present study, Sr0.7Bi0.2TiO3 is mixed with [(K0.5Bi0.5)(Mg1/3Nb2/3)O3] to form a solid solution of [(1 − x)SBT–x(KB)(MNb), x = 0.02, 0.04, 0.06, 0.1]. From the XRD results, it is indicated that KB is the main substituent for SBT ceramic at the A‐site. The breakdown strength (BDS) of ceramic gradually increases with an increase in doping content and achieves a high value of 280 kV/cm for x = 0.06. In addition, the 0.94SBT–0.06(KB)(MNb) ceramic shows excellent temperature stability (−55 to 140°C), a high recoverable energy density (Wd)—2.6 J/cm3, and an efficiency (η)—88% at 280 kV/cm. Therefore, 0.94SBT–0.06(KB)(MNb) ceramic is one of the possible materials for energy storage capacitor applications.

Nonlinear optical characteristics of chemical bath-deposited pure and Cu-doped SnO2 thin films: A comparative evaluation

A chemical bath deposition method is used to grow SnO2 thin films doped with copper (0, 1, 2, and 3 wt) on glass substrates that exhibit linear and nonlinear optical properties. XRD analysis of the films verified their polycrystalline phases oriented strongly of the c-axis along the preferred (110) direction depending on the doping concentration and substrate temperature. SEM images of pure SnO2 film showed the formation of granular cubic structures. Conversely, the Cu-doped films displayed the existence of spherical granules with porosity. The transmittance spectra of the films for UV–visible light indicated large values for pure films, and that the transmittance decreased with greater doping levels. As a result of copper ions in the nanostructures, it was found that the transmittance decreased as doping levels increased. Pure SnO2 has an optical band gap of 3.63 eV; it decreases with increasing Cu doping concentrations. Wemple-Di Domenico (WDD) model for single oscillator energy was used to estimate each oscillator's optical refractive index, while the static refractive index and dispersion energy were also determined. In addition, the film's WDD parameters and nonlinear refractive index were in the range of 320–1200 nm, and the wavelength was determined. During the doping concentration increase, the nonlinear refractive index of the films increased primarily because the linear refractive index of the films at 520 nm increased. This nonlinearity of the film may arise because of the thermal effect, saturated atomic absorption, and electrostriction. For pure SnO2, third-order nonlinear susceptibility (2.77 × 10-12m2/V2) is caused by thermal effects, and for doped samples, it is caused by photorefractive effects.

Dynamic photoluminescent and photochromic properties of CaAl12O19:Eu, Tb: A novel phosphor for advanced dual-modal multicolor anticounterfeiting

The integration of dynamic photoluminescence and photochromism to achieve dual-modal characteristics can substantially elevate the security of anticounterfeiting measures. In this study, a novel bifunctional phosphor, namely CaAl12O19:Eu, Tb possessing dynamic photoluminescence and photochromism, is developed by the sol-gel combustion method. As the duration of exposure to 254 nm ultraviolet radiation increases, the CaAl12O19:Eu, Tb phosphors exhibit exceptional dynamic luminescent characteristics and pronounced color changes. Furthermore, this exposure results in a photochromic phenomenon on the surface of the samples, causing a shift from white to light brown. With an increase in Tb doping concentration, distinct and diverse chromatic variations easily discernible are observed by the naked eye. In addition, the mechanisms underlying the dynamic photoluminescent and photochromic characteristics are analyzed herein. Furthermore, the application of the bifunctional phosphor CaAl12O19:Eu, Tb for advanced dual-modal multicolor anticounterfeiting is explored, offering enhanced security against duplication attempts.

Efficient bright green phosphor for white light-emitting diode using in backlight application

The (Ba,Ca)ScO2F:Bi3+,K+ phosphor with narrow emission band and green emission color peaking at 510 nm is demonstrated in the study. This phosphor is prepared using a solid-state reaction at high temperatures. Based on characterizing data, the increasing concentration of Ca2+ induces the shrinkage of the unit cell and the narrower spacing, leading to the increase in the photoluminescence of the phosphor. This also cause a red shift in the emitting range from 504 nm to 510 nm. The phosphor shows good absorption peaking at 415 nm, matching the excitation wavelength of the used nearultraviolet (UV) light emitting diode (LED) chip. When being applied in a white light‐emitting diodes (WLED) with 4,000 K, the phosphor could increase the luminous flux as its doping concentration increase. Besides, the WLED doping (Ba, Ca) ScO2F: Bi3+, K+ shows emission regions in blue, green, and red wavelength bands. The data from the study indicates that the phosphor is potential for developing the white-LED for backlight purposes.

Low temperature magnetic and structural properties of Sr-doped La2CoMnO6 (La2-xSrxCoMnO6: 0 ≤ x ≤ 0.08) double perovskite nanoparticles

A study on crystal structure and physical properties has been performed on nanoparticles of lead-free double perovskites, La2CoMnO6 (LCMO) and Sr-doped La2-xSrxCoMnO6 (LSMO:0 ≤ x ≤ 0.08) prepared by the sol–gel synthesis method. In preparation for the LSMO nanoparticle, the La site of the LCMO double perovskite was replaced with an increasing concentration of Sr atom. Structural investigation done by employing the X-ray Diffraction technique indicates that the crystallite size decreases as the doping concentration increases. The Rietveld refinement on the XRD pattern shows the formation of the rhombohedral phase of LCMO (S.G. no. 161). Strain in the prepared samples estimated from Williamson Hall (W-H) analysis shows that the strain decreases as crystallite size decreases. The presence of compressive strain is also evident from the blue shift obtained in the Raman spectrum of the nanoparticles. The UV–Vis spectra reveal the maximum absorption in the near UV region of the electromagnetic spectrum. The Bandgap analysis from Tauc’s plot shows an increase in band gap with Sr doping in the LCMO host lattice (from 1.81 eV to 1.92 eV). This is attributed to the decrease in crystallite size and octahedral tilting with Sr doping. Resistivity versus temperature plots reveal the semiconducting nature of the compound. A linear nature graph between lnρ and T-14 indicates that the electric transport mechanism is governed by the variable range Hopping (VRH) model. The M−H curves show that the maximum magnetization decreases as a result of Sr doping due to the anti-site disorder introduced. dM/dT vs T curve shows two magnetic transitions at ∼ 215 K and at ∼ 173 K which are due to Co2+–O2--Mn4+ and Co3+–O2--Mn4+ ferromagnetic superexchange interactions, respectively.

Monocrystalline silicon materials with the group IVA elements doped: A first-principles analysis

In this paper, the changes of lattice constant, stability and electronic structural properties of Si64−xMx (M=C, Ge, Sn, Pb; x=0, 1, 2, 3, 4) doped system under various doping types and concentrations were studied by using first principles calculation to determine the influence of doped IVA family elements on the properties of monocrystalline silicon materials. The results have shown that, the Ge, Sn and Pb doped systems will produce an expansion effect, and the lattice constant of the C doped system will decrease with the increasing of the number of doped atoms, and will have the greatest impact on the lattice constant of the system. The increase in defect formation energy is Pb¿C¿Sn¿Ge, the Ge doped system is the easiest to synthesize; and as the doping concentration increases, the defect formation energy of each doping system also increases, indicating that high concentration doping systems are more difficult to synthesize. There are no virtual frequencies in the phonon spectra of all doped systems, and the systems are thermally stable. In addition, doping will gradually reduce the bandgap width as the doping concentration increases. The band gap characteristics will also change: when doped with C, the system will become Metalloid; when doped with Ge, the system remains unchanged; when doped with Sn and Pb, the system will become a direct band gap semiconductor. From the perspective of band gap and charge differential density, the effect of different doping elements on enhancing electronic transitions is C¿Pb¿Sn¿Ge. This means that C doping system has the best improvement in conductivity.

Achieving high energy storage performance and efficiency in lead-free SrTiO3 ceramics via neodymium and lithium co-doping technique

ABSTRACT There is an immediate demand for eco-friendly, high-performance, and highly stable energy storage materials for pulse power systems. Ceramics based on SrTiO3 have a high breakdown strength (BDS) and dielectric constant. In this work, we fabricated a polycrystalline of Sr(1-x)(Nd, Li)xTiO3 ceramics via microwave-assisted heating of the starting materials. X-ray diffraction analysis reveals a pure perovskite phase without any secondary phase. Scanning electron microscopy images exhibit dense grain morphology with a decrease in grain size as the dopant concentration increases. The frequency dependences of the dielectric properties were studied in the frequency range of 100 Hz-1 MHz at room temperature. The polarization-electric field hysteresis loops were examined to ascertain the effect of co-doping on the energy-storage capability of SrTiO3 ceramics. After increasing the co-dopants from 0 to 8%, the energy density increased nine times (from 0.11 J/cm3 to 0.952 J/cm3), and the energy storage efficiency increased from 80.71% to 95.98%, respectively. In addition, the samples demonstrate excellent thermal stability, and their energy storage properties are stable up to 80°C. We may infer from this discovery that the bulk Nd3+ and Li+ co-doped SrTiO3 materials are good candidates for high-energy-density capacitor applications.

Modified physical properties of Ni doped ZnO NPs as potential photocatalyst and antibacterial agents

Hazardous organic dyes, present in the effluents of industries, are continuously polluting the environment. Photodegradation of these dyes on catalyst surface under sunlight irradiation is economic, safe and suitable strategy to protect environment. Hence, the synthesis and applications of Zn1-xNixO (x = 0.00, 0.02, 0.04, 0.06) NPs are reported here. Effect of pH and dopant concentration was studied to modify the electrical, magnetic, antibacterial and photocatalytic properties of Ni doped ZnO NPs. The samples were characterized by Scanning electron microscopy (SEM), Powder X-ray diffraction (XRD), UV–Visible spectroscopy (UV–Vis.), Energy-dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR) to determine the morphology, crystallite structure, optical properties, elemental composition and functional group detection, respectively. LCR meter and VSM were used to evaluate the dielectric properties and magnetic properties of Ni doped ZnO NPs, respectively. XRD pattern confirmed the presence of hexagonal wurtzite geometry of ZnO NPs. The structural and morphological analysis showed the increase in crystallinity with little effect on shape of doped NPs by increasing the dopant concentration and slight increase of pH. It was observed that the Ni doped ZnO NPs possess good photocatalytic potential by 94% degradation of 20 ppm solution of methyl orange dye (MO) in just 80 min under sunlight. Moreover, the enhancement in antibacterial potential was also observed with increase in dopant concentration and decrease in crystallite size of doped ZnO NPs. Smaller size NPs were found more effective against gram negative bacterial strains.

Structural, Morphological, Optical Properties and Impedance Analysis of Solution-Processable Ni-Doped CuO Thin Films on ITO/Glass Substrates

Cupric-oxide-based thin films with various amounts of 0, 1, 2, 3, and 4 wt.% Ni doping were, in turn, deposited on ITO/glass substrates via a solution process. The 0.25 M concentrated solutions of copper (II) acetate monohydrate and nickel acetate tetrahydrate were used as starting materials mixed in ethanol solvent, in order to form the precursors. We obtained that the crystalline structure was not affected by the increase in Ni doping concentration as evidenced by X-ray diffraction patterns. The surface morphology observed by scanning electron microscope pointed out the presence of linked-structure nanoparticles. The influence of Ni doping on the optical bandgap width was evaluated by using ultraviolet-visible spectrometry. We found that the optical bandgap should be direct, and it decreased from 2.69 to 2.38 eV for the range doped. Interestingly, we determined the relaxation time of the Ni-doped CuO/ITO/glass structure from measuring the electrochemical impedance spectroscopy, and it was 0.36 s for the undoped film, then gradually decreased to be 0.31, 0.11, 0.1, and 0.04 s with increasing the Ni doping concentration. This achievement result will serve as a foundation for the future photonic researches.

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.

Improve physical properties of zirconium doped strontium sulphide for optoelectronic purpose

The electrochemical deposition was used to synthesize zirconium-doped strontium sulphide materials at varying dopant concentrations of 0.01 to 0.03 mol. The surface micrograph of the zirconium doped films is well structured on the surface of the FTO used for the synthesis without any crack or lattice strain. The spectrum is polycrystalline with a cubic structure and a prominent peak at (111) orientation for SrS film. At the introduction of the zirconium dopant 0.01 mol, the peak intensity increases with a prominent peak at (211) which indicate acceptance of zirconium dopant in the precursor and as the dopant concentration rises the peak intensity decreases which depicts that a higher concentration of zirconium reduces the peak intensity of the films. The Williamson-Hall plot's slope increases as the dopant concentration increases. The materials exhibit a thickness increase of 121.32 to 126.13 nm and a decrease in film resistivity from 1.12 × 109 to 1.32 × 109 O.m, which further led to an increase in conductivity from 7.57 × 108 to 8.26 × 108 S/m. The bandgap energy of SrS is 1.50 eV while SrS-doped zirconium is 1.35 eV–2.52 eV.

Benchmarking the yttrium content in the low temperature/low humidity electrical properties of yttrium-doped barium cerate

Yttrium-doped barium cerate (BCY) is one of the best proton-conducting ceramics to be used in fuel cells/electrolyzers at intermediate temperatures, due to its high hydration enthalpy and high conductivity. Nonetheless, it has commonly been discarded for these applications due to its instability in the presence of carbonaceous and humidified atmospheres. A recent work has addressed this issue, by suggesting the use of this material in very low water vapor partial pressures (pH2O ∼ 10−4 atm) [Electrochimica Acta 334 (2020) 135625] and at low temperatures (T ≤ 400 °C). Under these conditions, BCY can still offer pure protonic conductivity while also offering suitable stability. In the current work, we provide a comprehensive analysis of the effects of the acceptor dopant concentration (Y2O3) in the structural, microstructural, and electrical properties in a wide compositional series of BaCe1-xYxO3-δ (x = 0.05, 0.10, 0.20 and 0.30) at low levels of humidity in the low temperature range (100–400 °C). The results show that BaCe0.9Y0.1O3-δ (BCY10) offers the highest bulk conductivity in these conditions, while further increase in dopant concentration leads to impairment due to “proton trapping” effects. In contrast, the specific grain boundary conductivity increases with increasing dopant concentration due to a reduction of Schottky barrier height at the space-charge layer. We demonstrate that, by operating at very low temperatures (e.g., below 400 °C), the peak performing, BCY10 material can still operate at very low levels of water vapor partial pressure (pH2O ∼ 10−4 atm), where its stability can be maintained. This work paves the way for the optimization of this material, with a focus on utilizing low humidity levels and low temperatures, where it can offer a competitive advantage over that of the majority of other proton-conducting perovskites for potential applications operating under these conditions.

Physical properties of multifunctional TM-doped ZnO nanorods and their photocatalytic and anti-bacterial activities.

Dilute magnetic semiconductor Zn1-xCuxO (x = 0, 1.5, 3.0, and 4.5%) nanorods were prepared by hydrothermal method. The impact of dopant concentration on the physical properties was investigated along with the anti-bacterial and photocatalytic activities. Synthesis of ZnO nanorods was confirmed by the characteristic band at 380nm in UV-Visible spectra of the synthesized samples. A red shift in absorbance spectra was observed from 380 to 465nm with an increase in dopant concentration. The hexagonal wurtzite geometry and rod-like morphology of Cu-doped ZnO nanorods having an average size of 29nm were confirmed by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM), respectively. An increase in the crystallinity of the material was observed with an increase in the dopant (Cu) ratio without any alteration in geometry. EDX analysis was used to confirm the purity of samples. FTIR spectra were recorded to explore the functional group present in samples. The hysteresis loop drawn by a vibrating-sample magnetometer (VSM) was utilized to analyze the ferromagnetic behavior. As-synthesized pure and Cu-ZnO nanorods were evaluated for their photocatalytic behavior for the photodegradation of methyl orange (MO) dye. Zn1 - xCuxO with x = 4.5%, pH 3, and catalyst dosage of 0.5g has shown the maximum efficiency. Results elucidated > 81% degradation of MO dye with a rate constant (k) value of - 1.930 × 10-2min-1 in just 90min of exposure to a visible light source. ZnO nanorods have also exhibited anti-bacterial potential against gram-positive and gram-negative strains of bacteria. However, smaller size nanorods were found more effective to suppress the growth of gram-negative bacteria. A slight decrease (11%) in catalytic potential was observed in the 5th cycle during recycling and reuse experiments.

X-ray/gamma radiation attenuation and cytotoxic properties of Gadolinium doped Maghemite nanoparticles

In the present work, Gadolinium doped (1–6 mol%) Maghemite nanoparticles (NPs) were synthesized via solution combustion method using Sapodilla fruit extract as a reducing agent followed by calcination at 500 °C and characterized with different techniques. The Bragg reflections consists of (hkl) planes corresponding to γ-Fe2O3 (Maghemite). Addition to this, few planes corresponding to α-Fe2O3 and Gd2O3 were also observed. The estimated crystallite size and direct energy band gap was found to decrease with increase in Gd3+ concentration. Cytotoxic properties were examined on cervical cancer cell lines HeLa cells as the Gadolinium dopant concentration increases, cell death decreases, eventually toxicity is going to reduced. Because of the non-toxicity, these NPs might be used as a drug carrier and also in the biochemical modification process called PEGylation. Theoretically, X-ray/Gamma ray attenuation parameter such as mass attenuation coefficient is studied in detail which is an essential parameter in radiation dosimetry. Gamma attenuation ion properties are increased by increase in the dopant concentration of Gadolinium. Compared to other concentrations, Gadolinium at 6 mol% shows maximum cytotoxic and mass attenuation coefficient. Thus, the present synthesized material might finds an application in biomedical field as well as in radiation dosimetry.

Atomic-scale carbon framework reconstruction enables nitrogen-doping up to 33.8 at% in graphene nanoribbon

Nitrogen-doping is well-known to be an effective and promising strategy to tune the electronic states and configurations of carbon materials for catalysis, energy conversion and storage. Since 2009, numerous investigations have demonstrated that the catalytic activity of the nitrogen-doped carbon materials can be improved with an increased doping concentration, yet, how to realize a high doping level remains a great challenge, and to what level remains an open and elusive question. Herein, we report an “in situ framework reconstruction of g-C3N4” that can provide a suitable and simple approach for Nitrogen-superdoping, where nitrogen vacancy formed at C-N = C site in the g-C3N4 framework help to activate adjacent C atoms that are endowed with unpaired electrons dwelling, thus, to be more active. Importantly, both density functional theory analyses and experiments reveal that they are energetically favorable to bond with an ethene molecule, reconstructing a π-bonded dual nitrogen-doped hexagonal-C ring that further acts as building block of the as-formed graphene nanoribbons. Finally, the nitrogen-doping level and the configuration can be finely tuned in a wide range, and up to 33.8 at% of nitrogen is homogenously doped. With the Nitrogen-superdoped graphene nanoribbons as counter electrodes in dye-sensitized solar cells, which have attracted wide attention due to their easy fabrication and relative high power conversion efficiency (PCE), a PCE of 8.60% is achieved. This present work represents a breakthrough in high-efficiency nitrogen-doping of carbon materials, and will fastly promote the chemistry, chemical engeering and material industry involved in carbon.

The effect of boron co-doping on thermoluminescence and optically stimulated luminescence properties of LiMgPO4:Tb,Sm

The effect of boron co-doping on optically stimulated luminescence (OSL) and thermoluminescence (TL) properties of LiMgPO4:Tb,Sm,B prepared by solid-state reaction was studied. The structure of the prepared materials was confirmed by X-ray diffraction. The TL glow curves of samples irradiated with different doses of β rays were tested. No matter how much B is doped, the peaks at 190 or 280 °C are for a first-order kinetic glow curve. The activation energy and frequency factor remained almost unchanged with the increase of boron doping concentration, which indicated the trap centers of LiMgPO4:Tb,Sm,B were independent of boron doping concentration. The E at 190 and 280 °C are around 1.16 eV and 1.55 eV. Photo-ionization cross-section showed significant changes and the sensitivity of OSL reached a maximum for a concentration of 4 mol% with increasing of boron doping concentration. B-doping enhanced the OSL-signal with a factor 2.6 when B concentration is 4 mol%. The repeatability of the powders for OSL were also studied and the relative standard deviation was less than 1.5%. The minimal detectable dose (MDD) of LiMgPO4:Tb,Sm,B with a boron doping concentration of 4 mol% was 8.2 μGy. This material has a fast decay time, good repeatability, low MDD and has further research value.