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Studies on structural, optical and magnetic properties of (Ru, Mn) codoped ZnO nanostructures
摘要： Ruthenium and manganese codoped ZnO (RuxMn0.01Zn0.99-xO; x = 0.01, 0.02 and 0.03) were synthesized by sol-gel method via ultrasonication. The effects of codoping on structural, microstructural, optical and magnetic properties of the as-synthesized materials were characterized through X-ray diffraction (XRD), high resolution scanning electron microscopy (HRSEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL) and SQUID magnetometer, respectively. From the XRD pattern, it is evident that all the diffraction peaks can be indexed to the hexagonal wurtzite structure and shows the incorporation of dopants ie. Ru and Mn are substituted in the ZnO lattice. Nanosphere like morphology was observed in HRTEM analysis and the average particle sizes are found to be 20-30 nm, which are good agreement with the XRD crystallite size by Scherrer formula. Photoluminescence (PL) studies were carried out to investigate the optical properties of the as-synthesized materials and the defects related strong green emission peaks was observed in the TM codoped ZnO samples. It can be clearly seen from SQUID results, the loop is linear with the field indicating the presence of paramagnetism / anti ferromagnetism in the samples.
关键词： ZnO,sol-gel,optical properties,codoping,ultrasonication,magnetic properties,structural properties
更新于2025-09-10 09:29:36
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Codoping Er-N to Suppress Self-Compensation Donors for Stable <i>p</i> -Type Zinc Oxide
摘要： Stable p-type doping of zinc oxide (ZnO) is an unsolved but critical issue for ultraviolet optoelectronic applications despite extensive investigations. Here, an Er-N codoping strategy for defect engineering of ZnO to suppress the self-compensation of the donor-type intrinsic point defects (IPDs) over the acceptor-type ones is proposed. Via first-principles calculations, the influence of nitrogen and erbium concentration on the stability of ZnO is investigated. The complex (ErZn-mNO) consisting of multiple substitutional N on O sites and one substitutional Er on Zn site is a crucial stabilizer. With an increase of the concentration of N, the absorption edges redshift to lower energy due to the impurity band broadening in the bandgap. The results suggest that codoping Er-N into the ZnO matrix is a feasible way to manufacture stable p-type ZnO.
关键词： p-type ZnO,Er-N codoping,first principles,defect formation energy
更新于2025-09-10 09:29:36
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Tunable luminescent properties of BaGd <sub/>2</sub> O <sub/>4</sub> :Eu <sup>3+</sup> scintillating phosphors by Pr <sup>3+</sup> -codoping
摘要： BaGd2O4:Eu3+ scintillating phosphors by Pr3+‐codoping were synthesized at 1300°C in air using a solid‐state reaction method. The as‐synthesized phosphors were characterized by X‐ray diffraction (XRD), photoluminescence (PL) including excitation radioluminescence (RL) spectra excited by X‐ray and and emission spectra, thermoluminescence (TL) spectra. Both the PL and RL spectra are composed of the featured trivalent europium (Eu3+) without any praseodymium (Pr3+) ions, and the PL and RL intensities as well as the lifetimes of BaGd2O4:Eu3+ scintillating phosphors decrease dramatically with an increasing concentration of Pr3+ ions. Finally, the TL spectra reveal the trap concentration of the existing defects decrease with an increasing concentration of Pr3+ ions, while the relative TL intensity ratio of the high temperature band to the low temperature one increases with an increasing concentration of Pr3+ ions, which results in the afterglow suppression of BaGd2O4: Eu3+ scintillating phosphors.
关键词： radioluminescence,photoluminescence,BaGd2O4:Eu3+ scintillating phosphors by Pr3+‐codoping,thermoluminescence
更新于2025-09-09 09:28:46
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Nitric Oxide Detector Based on WO <sub/>3</sub> -1wt%In <sub/>2</sub> O <sub/>3</sub> -1wt%Nb <sub/>2</sub> O <sub/>5</sub> with State-of-the-Art Selectivity and ppb-Level Sensitivity
摘要： Fast, sensitive, and precise detection of nitric oxide (NO) is critical to many applications in environmental monitoring and early disease diagnosis via respiratory testing. An effective detection system requires a sensor to detect NO gas at the parts per billion (ppb) level, and this system should possess a high degree of anti-interference selectivity. To achieve these targets, a series of gas sensor thin films based on intrinsic WO3, one-additive-doped WO3 (prepared by doping In2O3 or Nb2O5), and two-additive-doped WO3 (synthesized by doping with In2O3 and Nb2O5) oxides were successfully grown. By analyzing the properties of sensitivity, selectivity, responsiveness, and recovery time of the gas sensors, we found that WO3-1wt%In2O3-1wt%Nb2O5 has overwhelming advantages over intrinsic WO3, WO3-In2O3, and WO3-Nb2O5. A sensing response value of 2.4 was observed for NO concentrations as low as 20 ppb from the WO3-1wt%In2O3-1wt%Nb2O5 sensor. With 100 ppb NO gas, the WO3-1wt%In2O3-1wt%Nb2O5 sensor achieved a high response of 56.1 at 70 °C, which is a state-of-the-art performance for NO detection at low working temperature settings. WO3-1wt%In2O3-1wt%Nb2O5 also yields significantly improved selectivity and stability over intrinsic WO3, WO3-In2O3, and WO3-Nb2O5. Studies on the sensing mechanism show that the grain size, rather than the n?n heterostructure effect, plays a dominant role in the observed results. By decreasing the grain size so that it is close to the thickness of the space-charge layer, the sensing response is enhanced. Although room remains to further improve the sensing properties, the performance of WO3-1wt%In2O3-1wt%Nb2O5 is sufficient for implementation in low-content NO detection devices.
关键词： codoping,high selectivity,NO gas sensor,limit of detection (LOD),ppb-level response,pulsed laser deposition (PLD)
更新于2025-09-09 09:28:46
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Synthesis of Li+-ion activated NaYF4: Er3+/Yb3+ phosphors via a modified solid-state process for latent fingerprint detection
摘要： Li+-ion codoped NaYF4: Er3+/Yb3+ phosphors (β-NaYF4) with a hexagonal structure were synthesized via a modified solid-state route. High-speed planetary ball milling and solid-liquid mixing were simultaneously used to overcome the drawbacks of high synthesis temperatures in conventional routes. A pure β-NaYF4 phase was obtained through calcination at 600°C for 3 h. Increases in the codoping content of Li+ ion caused a slight shift in X-ray diffraction peak positions toward high angles owing to the distortion of the local crystal field. Field emission scanning electron microscope images showed agglomerated spherical particles of approximately 0.7 μm with narrow size distribution. The upconversion properties of β-NaYF4 codoped with Li+-ion were explored. Two emission bands in the green regions (520 nm and 545 nm) and one emission band in the red region (615 nm) were observed owing to the 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2 transitions of Er3+, respectively. Codoping with 6 mol% Li+ increased the upconversion intensity by three times, which was explained using the energy level diagram. The present phosphors with improved upconversion properties were utilized for latent fingerprint detection on smooth surfaces of regularly used polymer sheets, glass substrates, and compact discs. Using the present phosphors, the base elements with three-level features, such as sharp ridges, valleys, ridge flow, bifurcation, ridge shapes, and dots, were observed on all hydrophilic and hydrophobic surfaces. The prepared phosphors exhibited promising characteristics to detect the features of fingerprint impression for individual identification in forensic applications.
关键词： fingerprint detection,solid-liquid mixing,upconversion,ball milling,Li+-ion codoping
更新于2025-09-09 09:28:46
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Improvement of response time in GAGG:Ce scintillation crystals by magnesium codoping
摘要： Dynamics of the population of the excited Ce states responsible for the luminescence response time in Gd3Al2Ga3O12:Ce scintillating crystals is studied by revealing the dynamics of nonequilibrium carriers in the picosecond domain. Optical pump and probe technique exploiting selective excitation of structural units of the crystal and probing the induced absorption as a function of time and spectral position is exploited. A fast response within a few picoseconds due to the absorption by holes at Gd ions and by electrons occupying the first excited state of Ce ions with the intracenter relaxation time of 500 fs are identified. Trapping of nonequilibrium electrons during their migration through the matrix to the emitting Ce ions are shown to be responsible for the slow component in the population of the excited Ce state. Elimination of the slow component is evidenced even at Mg codoping as low as 10 ppm. The elimination correlates with the acceleration of the response in coincidence time resolution experiments showing potential of GAGG:Ce, Mg in medical and high-energy physics applications.
关键词： response time,nonequilibrium carriers,optical pump and probe technique,magnesium codoping,scintillation crystals,GAGG:Ce,coincidence time resolution
更新于2025-09-04 15:30:14