Co-doping Concentration Research Articles

Growth and optimization of the scintillation properties of Gd3(Ga,Al)5O12 single crystals for WGI applications

A new scintillator was developed as a scatterer for whole gamma imaging (WGI). The WGI scatterer should simultaneously satisfy the three main characteristics: energy resolution (5.5 % or less), light yield (40,000 photons/MeV or more), and decay time (100 ns or less). Several scintillators were selected and evaluated among previously grown single crystals, and the candidate scintillator crystal was selected as the base for optimization, with energy resolution as the top priority. Based on the selected crystal composition, large single crystals were grown using the Czochralski method, and the Ga/Al ratio of the GAGG-type host crystal and Mg co-doping concentration were adjusted for optimization. The crystal grown after optimization exhibited scintillation properties with an energy resolution of 5.28 % at 662 keV, a light yield of 45,200 photons/MeV, and a decay time of 92 ns. After evaluating their characteristics by manufacturing them in a 4 × 4 array, the single crystals used in the production of a full-block array for the scatterers were finally selected. The energy resolution of the 14 × 14 full-block array was almost identical to that of the 4 × 4 array. No performance degradation was observed, even with a full-block array. Array blocks produced using the grown crystals are being tested by applying them to a WGI prototype at the National Institutes for Quantum Science and Technology, Chiba, Japan.

NIR reflective yellow pigment derived from gadolinium phosphate by doping bismuth and vanadium

This paper investigates the novel series of Near-infrared (NIR) reflective pigments with the general formula Gd1-xBix(P1-yVyO4) prepared via the facile hydrothermal method [where, x=y=0, 0.05, 0.1, 0.2, and 0.5]. The synthesized compounds were examined by XRD, XPS, FTIR, UV-Vis DRS, SEM and TEM characterization techniques. Bismuth, vanadium co-doping in GdPO4 host lattice unaltered the phase structure up to x=y=0.1. At higher co-dopant concentrations, the distortion in the phase structure leads to the formation of the mixed phases. Among the individual Bi3+ and V5+ doped GdPO4, the vanadium-doped GdPO4 showed an effective band gap reduction because of the contribution of V3d orbital from dopant element which leads to the color changes. However, vanadium doping drastically reduced the reflectance property of the compound. On the other hand, by bismuth and vanadium co-doping, the band gap was tuned to give a bright yellow color with significant changes in reflectance property. From the prepared compounds, Gd0.9Bi0.1(P0.9V0.1O4) composition showed a hexagonal phase of gadolinium phosphate hydrate with b* value of 34.58 and a reflectance value of 72.92 %. The shape of the particles was identified as nanorod by HRTEM analysis with good chemical and thermal stability.

Significantly enhanced piezoelectric properties in PMN-PT transparent ceramics by Sm/Pr co-doping

Transparent ceramics with high piezoelectricity offer potential applications in the development of advanced photoelectron and sensor devices. However, preparing ceramics with high optical transmittance and good piezoelectricity is a great challenge. In this study, Sm and Pr ions co-doped 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-PT) transparent piezoelectric ceramics were prepared, and the effects of Sm/Pr co-doping content on the ferroelectric, piezoelectric, dielectric, impedance properties of PMN-PT transparent ceramics were investigated. Finally, the prepared ceramics exhibit an optical transmittance of 64.1% at 900nm and an ultra-high piezoelectric coefficient d33 of 1310 pC/N. The performance indicates that Sm/Pr co-doped PMN-PT ceramic has a promising potential for developing multifunctional optical-acoustic-electric coupling devices.

Synergistic enhancement of Co doped Ni/NiOx nanofilms for catalytic hydrolysis towards ammonia borane

Transition metal catalysts exhibit a potential application for the hydrolytic dehydrogenation of ammonia borane (AB). The regulation of active sites through heterogeneous metal doping have been acknowledged as an efficient technology. Herein, Co-doped Ni/NiO nanofilms (Ni/NiCoOx-Y, Y is Co/(Co + Ni) atom ratio) were synthesized on an ionic liquid (IL)/water interface, in which Co atoms are uniformly doped in the basal NiO crystal lattice in the form of Co ions. The Ni/NiCoOx-Y catalysts exhibit a “volcanic” relationship between the catalytic activities for AB hydrolysis and Co-doped content. The optimized Ni/NiCoOx-20 nanofilms exhibit observably enhanced catalytic activity for AB hydrolysis, completely producing H2 within 4 min with a turnover frequency of 12.93 molH2·molmetal−1·min−1 and a low activation energy of 39.57 kJ mol−1. Moreover, Co doping can effectively enhance the stability of Ni-based nanofilms. The incorporation of Co ions into Ni/NiO crystal lattice slightly increases Ni electron density or Ni lattice expansion. Thus “electronic effect” strengthens the adsorption of H2O/intermediates and further beneficially accelerate combination of AB and H2O molecules, contributing to the improved catalytic activity. Meantime, the strong interaction of Co–Ni atoms can utilize the synergistic enhancement effect.

Structural, Optical, Magnetic, and Dielectric Investigations of Pure and Co-Doped La0.67Sr0.33Mn1-x-yZnxCoyO3 Manganites with (0.00 < x + y < 0.20)

Here, we report the structural, optical, magnetic, and dielectric properties of La0.67Sr0.33Mn1-x-yZnxCoyO3 manganite with various x and y values (0.025 < x + y < 0.20). The pure and co-doped samples are called S1, S2, S3, S4, and S5, with (x + y) = 0.00, 0.025, 0.05, 0.10, and 0.20, respectively. The XRD confirmed a monoclinic structure for all the samples, such that the unit cell volume and the size of the crystallite and grain were generally decreased by increasing the co-doping content (x + y). The opposite was true for the behaviors of the porosity, the Debye temperature, and the elastic modulus. The energy gap Eg was 3.85 eV for S1, but it decreased to 3.82, 3.75, and 3.65 eV for S2, S5, and S3. Meanwhile, it increased and went to its maximum value of 3.95 eV for S4. The values of the single and dispersion energies (Eo, Ed) were 9.55 and 41.88 eV for S1, but they were decreased by co-doping. The samples exhibited paramagnetic behaviors at 300 K, but they showed ferromagnetic behaviors at 10 K. For both temperatures, the saturated magnetizations (Ms) were increased by increasing the co-doping content and they reached their maximum values of 1.27 and 15.08 (emu/g) for S4. At 300 K, the co-doping changed the magnetic material from hard to soft, but it changed from soft to hard at 10 K. In field cooling (FC), the samples showed diamagnetic regime behavior (M < 0) below 80 K, but this behavior was completely absent for zero field cooling (ZFC). In parallel, co-doping of up to 0.10 (S4) decreased the dielectric constant, AC conductivity, and effective capacitance, whereas the electric modulus, impedance, and bulk resistance were increased. The analysis of the electric modulus showed the presence of relaxation peaks for all the samples. These outcomes show a good correlation between the different properties and indicate that co-doping of up to 0.10 of Zn and Co in place of Mn in La:113 compounds is beneficial for elastic deformation, optoelectronics, Li-batteries, and spintronic devices.

A comprehensive role of co-doping (Ce, Al) in dielectric, magnetic, and optical properties of NiO for its efficient use in magneto-optical and spintronics device applications

The crystalline NiO is prepared within the configuration Ni1-xCexAlxO (x = 0.00, 0.05, and 0.1) using a hydrothermal process. XRD and SEM analyses were conducted to examine the crystal structure and morphology of samples which reveals highly crystalline nature and uniform morphology, respectively. UV-spectra confirms the optical band gap lies in the range of 1.63–3.41 eV. The pristine NiO has a band gap of 3.42 eV which lies in the insulating properties range, while the insertion of co-dopant concentration causes to reduction of the band gap up to 1.63 eV which lies in the semiconducting properties range that ensures the higher electronic conduction. The PL spectra show that the luminescence intensity is highly reduced with the insertion of co-dopant ions in the NiO lattice which is the confirmation of higher sensitivity. Raman spectra reveal the formation and purity of the samples due to the non-existence of secondary Raman modes related to the Ce and Al dopants and are well-matched with XRD results. The magnetic measurements reveal the enhancement in remanace magnetization and saturation magnetization with the reduction in coercivity and square ratio showing that the doping of Ce and Al into NiO is influencing its antiferromagnetic nature. NiO may be showing altered magnetic characteristics with the possible contribution from ferrimagnetic or ferromagnetic phases, as the dopant affects the magnetic interactions. Dielectric measurements reveal the increase in capacitance, conductance, energy dissipation, energy storage, and decrease in resistance with the increase in co-dopant concentrations. Based on the obtained results, NiO with 10 % (Ce, Al) co-doping is a suitable candidate for efficient use in magneto-optical and spintronics device applications.

Influence of substrate temperature and Mn/Y co-doping concentration on the morphological, structural and optical properties of CuO nanostructured film deposited by the spray pyrolysis method

In this work, the effect of substrate temperature (ST) during deposition and dopant amount of Mn (1,3,5, and 7 %) and Y(3 %), (Mn/Y), on the physical properties of copper oxide (CuO) the nanostructured film were analyzed using different diagnostic tools. The pure and (Mn, Y) co-doped CuO thin films were deposited by the spray pyrolysis method, which is effective and easy to apply for any substrate. Deposited pure and (Mn,Y) co-doped CuO nanostructured films were investigated by X-ray diffraction (XRD), UV–Vis spectroscopy, and Field emission scanning electron microscopy (FESEM) techniques to analyze the influence of ST and co-doping on the structural, morphological, and optical properties of prepared films. The FESEM is used to visualize nanostructures on the surface of the film. Also, it is observed that the surface morphology of CuO film changes from a spherical-like to a nanocloumnar-like structure with increasing substrate temperature. The XRD diffractograms confirm the monoclinic crystal structure of CuO, in polycrystalline nature for all deposited films. UV–Vis spectra suggest changing the optical absorbance and the band gap of the pure and Mn/Y co-doped CuO nanostructured films. In the first investigation of this study, the better substrate temperature was obtained as 400 °C according to results. In the second part, the effect of Y and Mn doping with different content was analyzed for the CuO film deposited at the chosen ST of 400 °C. There is no observable crystalline structure variation in the XRD pattern, but the size of nanostructure and dislocation density are varied with Mn/Y co-doping. FESEM micrographs confirm the impact of the co-doping concentration on the size, shape, and surface properties of CuO nanostructured film. In addition, the optical band gap increases with Mn doping up to 3 % of Mn content and it was determined as 2.69 eV for the sample 3Mn/Y@CuO nanostructured film. The obtained results suggest that the substrate temperature has an important impact on the physical properties of the spray deposited CuO nanostructured film, and the structural, optical, and surface properties of the CuO nanostructured films may be engineered by Mn/Y doping concentration.

Preparation, characterization and biological activity of Co-doped ZnO nanostructured thin film: A comprehensive study on its photo-physical properties and antimicrobial efficacy against food-borne pathogen

The Co@ZnO thin film deposited on glass substrate with dopant contents of cobalt ranging from 0 to 10 % were fabricated using spray pyrolysis coating method. The prepared nanocomposite thin film was characterized by scanning electron microscopy, X-ray diffraction, UV–vis and Raman spectroscopy. Some surfaces structural probing of the deposited samples confirmed nanolamination of hexagonal wurtzite phase of ZnO with no other impurity phases and high adherence on the soda lime glass substrate. Average grain sizes (56–43 nm) and lattice strain of the films were found to be tailored with the variation of Co-dopant content, signifying phonon confinement or defect/disorder caused by the Co-dopant impurity on the ZnO host particle owing to the impurity levels and oxygen vacancy states. The film demonstrated high optical transmittance with enhanced photoabsorbtion and narrow optical band gap (3.24–2.64 eV) with increasing Co-dopant content. In evaluating its antibacterial efficacy, the Co@ZnO thin film was tested at different dopant concentration against Bacillus cereus (foodborne pathogen). The result revealed that the films exhibits excellent inhibitory effect on the pathogen, with highest activity obtained at 10 % Co@ZnO. Furthermore, a more improved inhibitory activity was recorded when at 10 % Co@ZnO dopant was exposed to UV irradiation.

Enhancement of dielectric constant in Sm:Zr co-doped HfO2 films synthesized by cost-effective method

Sm, Zr co-doped HfO2 films were deposited on a p-type silicon wafer using a cost-effective spin coating method. The influence of Sm, Zr co-doping concentration variation on structural, compositional, morphological, and electrical properties was examined. The dominance of the orthorhombic phase (o-phase) in comparison to the monoclinic phase was noted to rise with the simultaneous increment of Sm doping concentration and decrement of Zr concentration. A decrease in oxygen vacancies was noted for all the Sm, Zr co-doped HfO2 films from XPS results. Nonporous and uniform distribution of grains was observed from Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM) studies. Electrical studies of MOS capacitors based on Sm, Zr co-doped HfO2 films revealed a low leakage current. C-V studies exhibited an increment of dielectric constant and a decrement of interface trap densities. Further, to obtain insights into the microscopic features of Sm, Zr co-doped films, impedance and modulus studies have been performed. The obtained results imply the potential of tuning Sm, Zr co-doping concentrations in HfO2 towards stabilization of the orthorhombic phase and to enhance the dielectric constant of the films.

Solution-processed Tb: Zr co-doped In2O3 thin film transistor and its dual effect on improving photostability

In this paper, Tb: Zr co-doped In2O3 TFTs were fabricated using an aqueous route. The dual effect of Tb: Zr co-doping on improving photostability was addressed. At a 5 mol% co-doping concentration, the ΔVth under NBIS first decreased and then increased as Tb: Zr ratio increased. The optimized co-doped sample (1: 2) showed a ΔVth of −3.22 V, compared to the undoped sample of −9.5 V and the single-doped samples (1: 0 and 0: 1) of −4.4 V and −4.15 V respectively. The defect state was evaluated using μ-PCD. The peak value and τ2 first decreased and then increased with an increase in Zr ratio, and reached their minimum values when the Tb: Zr co-doping ratio was 2: 1 and 1: 2, respectively. This suggested that co-doping can introduce more deep level states for the rapid recombination of photogenerated carriers and reduce shallow level states, leading to superior photostability of the co-doped devices. Further characterization by UV-Vis and XPS indicated that the increase in band gap and the decrease in oxygen vacancy were also contributing factors to improved device stability. These results highlight the great potential of solution-processed Tb: Zr co-doped In2O3 TFT for applications in low-cost and high-stability electronics.

Enhanced multiferroic properties of Co-doped BiFeO3 nanoparticles via structural changes

The present study demonstrates a rhombohedral-to-orthorhombic phase transition of BiFe1-XCoXO3 (BFCXO, x = 0, 0.01, 0.03, and 0.05) nanoparticles induced by Co ion doping. With increasing concentration of Co dopant, XRD, Raman and IR patterns exhibit lattice shrinkage and increased lattice strain; SEM and TEM images reveal a corresponding reduction in grain size; XPS spectra indicate that the Fe2+ ions are readily oxidized by Co3+ to Fe3+ ions because to the greater oxidation–reduction potential of Fe3+/Fe2+ (1.3 eV) than that of Co3+/Co2+ (0.55 eV). Effective regulation of crystal structure and microstructure significantly alters the multiferroic properties of BFCXO samples. The Co-doped samples gradually transition from antiferromagnetism to ferromagnetism. Among them, BFC0.03O reaches its maximum values at Ms ~ 0.956 emu/g for magnetization saturation and Mr ~ 0.054 emu/g for remanent magnetization. Meanwhile, BFC0.03O exhibits better ferroelectric properties compared to its pure counterpart. This study presents an effective approach for controlling the structure and characteristics of BFO-based nanomaterials for multifunctional device applications.

Optimized Bridgman growth of Cs2LiYCl6:Ce single crystals and energy resolution improvement by codoping

Cs2LiYCl6:Ce is a novel scintillation crystal with good energy resolution, high light yield, and outstanding neutron/gamma discrimination capability. However, its complex composition and incongruent melting behavior pose many challenges to the crystal growth. In this study, five different compositions of Cs2LiYCl6:Ce crystals were grown using the vertical Bridgman method. These compositions included LiCl at 57 mol%, 60 mol%, and 63 mol%, as well as CsCl and YCl3 at ratios of 1.9:1 and 2.1:1. It was found that the highest CLYC phase volume fraction could be obtained in the recipe with a LiCl composition of 60 mol%, while changing the ratio of CsCl to YCl3 did not show any significant positive effect on crystal growth. In addition, Ca2+/Sr2+ was applied to modify the scintillation performance of CLYC:Ce. A batch of Φ11mm crystals with different co-doping concentrations of Ca2+ and Sr2+ were successfully grown by using the Multi-ampoule Bridgman method, no cracks or inclusions were observed in the grown crystals. Co-doping showed little effect on the radiation luminescence and transmittance spectra of CLYC. The scintillation decay curves demonstrated that the decay times depend on the co-doping concentration. Most notably, the energy resolution of CLYC:Ce is improved from 4.6 % to 3.8 % by co-doping 0.05 % Sr2+ under 662 keV gamma-ray excitation. However, the light yield is reduced because of co-doping of Ca2+ and Sr2+, especially Ca2+ having a more pronounced effect.

Effects of high valency and polarizability ion (W6+) on the phase evolution of CaZr1–2xLn2xTi2–xWxO7 zirconolite-based solid solution (Ln = Nd, Sm, Gd, Ho, Yb)

Zirconolite-based structures have served as robust matrices for the incorporation of minor actinide-rich high-level waste (HLW). The co-doping effects are critical for exploring the phase evolution of zirconolite-based structures, thereby providing a guide for HLW immobilization. Nevertheless, few studies have studied the synergistic effect of high valent ion W6+ and Lanthanides (Ln, surrogates to minor actinides) co-doping. This study proposed a systematical study on the Ln-W (Ln = Nd, Sm, Gd, Ho, Yb) co-doping in zirconolite-derived structure using X-ray diffraction (XRD) and scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDX). The results showed that near-single-phase zirconolite-2M was recorded for samples with low level doping of Ln-W (Nd–W, Sm–W and Gd–W with x = 0.05; Ho–W and Yb–W with x = 0.05–0.1), and its structure underwent a moderate expansion along the c-axis, as revealed by a Pawley refinement method. One key finding is that near-single-phase zirconolite-2M was recorded for samples with low level doping of Ln-W (Nd–W, Sm–W and Gd–W with x = 0.05; Ho–W and Yb–W with x = 0.05–0.1), and its structure underwent a moderate expansion along the c-axis, as revealed by a Pawley refinement method. Notably, in addition to a transformation from zirconolite-2M to pyrochlore, a pseudo-yellow phase CaWO4 was also noted with increasing co-doping contents. This work demonstrates that the high charge compensator W6+ and lanthanides can be simultaneously incorporated into zirconolite structure, and a different phase transformation was revealed compared to that in low valent element doping system, which gives a new insight into the optimization of HLW immobilization route.

Enhancement of redox cycling stability of Ni/GDC cermets for intermediate-temperature SOFC anodes through Ge incorporation in the ceramic phase

In this study, Ge4+ was incorporated into the ceramic matrix of nickel-based anode materials, synthesizing anode materials NiO-Gd0.1Ce0.9-xGexO1.95 (x = 0.01, 0.04, 0.07) and NiO-Ce0.9Gd0.1O2–δ. Corresponding anode support samples were also prepared, designated as A-CGDC, A-C1Ge, A-C4Ge, and A-C7Ge. Additionally, single cell samples using the newly co-doped anode materials were prepared, identified as C-CGDC, C-C1Ge, C-C4Ge, and C-C7Ge. The research indicates that after doping the ceramic phase framework with Ge4+, these composite anode materials exhibit the potential to withstand more redox cycles than C-CGDC without catastrophic mechanical structural damage or degradation in electrochemical performance. Particularly, after incorporating 7mol% Ge4+ into the ceramic backbone, the issue of 86 % strain accumulation in the anode support was mitigated. Additionally, the ion doping ratio is closely linked to the stability of the single cell samples, with the A-C7Ge sample able to withstand up to 11 extreme recycling sessions at 700 °C without complete structural failure, improving structural stability by approximately 57 % compared to A-C1Ge. In terms of electrochemical output performance, the impedance of C-C1Ge prior to complete failure was nearly double that before oxidation-reduction, with a maximum power density reduction of about 26.47 %. As the co-doping concentration in the ceramic phase reached 7mol%, the impedance increase during single cell cycle testing was about four times smaller, with C-C7Ge 's impedance before mechanical failure only 37 % higher than before cycling, and a reduction in maximum power density of just 11.11 %. Moreover, during consecutive cycling tests, the average damage to the open-circuit voltage was only 0.02V, showing almost no negative impact from the cycling operations, and it maintained efficient output performance after multiple cycles. Therefore, the newly synthesized nickel-based anode materials, modified via co-doping methods within the ceramic phase, can be considered as potential composite anode materials for intermediate-temperature solid oxide fuel cells.

High-Performance Tin Oxide Thin-Film Transistors Realized by Codoping and Their Application in Logic Circuits.

Tin oxide is a promising channel material, offering the advantages of being low-cost and environmentally friendly and having a wide band gap. However, despite the high electron mobility of SnO2 in bulk, the corresponding thin-film transistors (TFTs) generally exhibit moderate performance, hindering their widespread application. Herein, we proposed a codoping strategy to improve both the electrical property and the stability of SnO2 TFTs. A comparative analysis between doped and undoped SnO2 was conducted. It is observed that taking advantage of the difference in ionic radii between two dopants (indium and gallium) and the tin ions in the host lattice can effectively reduce impurity-induced strain. Additionally, we investigated the effect of codoping content on SnO2 TFTs. The optimal codoped SnO2 (TIGO) TFTs demonstrate high performance, featuring a field-effect mobility of 15.9 cm2/V·s, a threshold voltage of 0.2 V, a subthreshold swing of 0.5 V/decade, and an on-to-off current ratio of 2.2 × 107. Furthermore, the devices show high stability under both positive and negative bias stress conditions with a small threshold voltage shift of 1.8 and -1.2 V, respectively. Utilizing the TIGO TFTs, we successfully constructed a resistor-loaded unipolar inverter with a high gain of 10.76. This study highlights the potential of codoped SnO2 TFTs for advanced applications in electronic devices.

Energy transfer of Er3+-Nd3+ co-doped in tellurite glass via energy level match

Er3+/Nd3+ co-doped tellurate glass was prepared by melt quenching method. The relationship between the energy levels of two rare earth ions was studied by absorption spectra and excitation spectra. At 379/407/488 nm excitation, visible light, near-infrared (NIR) emission spectra, and fluorescence attenuation curves were measured. The NIR emission spectrum and fluorescence lifetime show that Er3+ can transfer energy to Nd3+, thus enhancing the NIR emission of Nd3+ in tellurate glass. In the co-doped sample, under excitation of 379/407/488 nm, the NIR emission of Nd3+ has a concentration quenching point related to Er3+, and the optimal co-doped concentration is 1mol% ErF3. At 365/451 nm excitation, NIR emission was not enhanced and no energy transfer occurred. In contrast to the energy transfer between conventional Er3+-Nd3+ co-doped glasses, this paper investigates the effect of matching the higher Er3+ energy levels with adjacent Nd3+ levels on the energy transfer. The energy transfer process of Er3+-Nd3+ co-doped glasses is studied in the energy level diagram.

Comparing Pr3+ and Nd3+ for deactivating the Er3+: 4I13/2 level in lanthanum titanate glass

Erbium lanthanum titanate glasses were prepared by levitation melting for the spectroscopic study of ways to promote the mid-infrared fluorescence. Two series of heavily erbium doped glasses (15 wt%) were prepared with the addition of either Pr3+ or Nd3+ in amounts relative to Er3+ of 0.05, 0.1, and 0.2. Both ions quench the lower Er3+ laser level with the Pr3+ doing so more rapidly. Although high co-dopant concentrations result in higher energy transfer, as clearly evidenced in upconversion and downconversion fluorescence measurements, the mid-infrared lifetime also suffers a reduction and, therefore, a balance must be struck in the co-dopant concentration. Lifetime and spectral measurements indicate that, at a fixed relative co-dopant amount, Pr3+ is more effective than Nd3+ at removing the bottleneck of the Er3+ 4I13/2 level. Moreover, consideration of the lifetimes alongside the absorption data of the individual ions indicates that despite the large absorption cross-section of Nd3+ at 808 nm, the concentration needed to yield more absorbed power than utilizing direct 976 nm excitation of Er3+ results in unfavorable lifetimes of the mid-infrared transition. In the end, Pr3+ prevails as the superior co-dopant in terms of the effects on fluorescence lifetimes as well as potential laser system design considerations. In a unique self-doping approach, a reducing melt atmosphere of Ar instead of O2 creates a small fraction of Ti3+. In 5Er2O3-12La2O3-83TiO2 glass, the presence of Ti3+ quenches the 4I13/2 emission about 2.6 times more than the 4I11/2 when lifetimes are compared to an O2 melt environment. As an additional means of increasing the mid-infrared emission, the effect of temperature on the mid- and near- infrared lifetimes of a lightly doped lanthanum titanate composition is investigated between 77-300 K. The mid-infrared lifetime increases by ∼30% while the near-infrared lifetime increases by ∼10%, which suggests in addition to co-doping, active cooling of the gain media will further enhance performance.

Synthesis, characterization, DFT calculations, and anticancer properties of VI-period and f-block elements-substituted zinc oxide nanopowders

Nanotechnology provides promising ways in which a wide range of new materials can be manufactured which appear to have enormous potential in the field of biomedicine and life sciences. ZnO can be applied in many physical and optical processes and used as a good anti-cancer agent. ZnO NPs are recognized as SAFE or GRAS, non-toxic and biocompatible particles. In this study, wurtzite ZnO samples co-doped by rare earth elements (Tb, Er) were prepared via sol-gel auto-combustion route and their crystallographic structure as well as their morphologies were examined using XRD and TEM techniques. The analysis disclosed that all synthesized products crystallized in a hexagonal structure and the crystallites/particles size diminished with the increase of co-doping content. The electronic structure and optical properties of the different products were assessed using DFT calculations. Doping Tb and Er rare earth elements into ZnO has a significant effect on its optoelectronic properties. The computational study showed that the co-doping of Tb and Er on pure ZnO decreased the band gap and increased the refractive index. The extinction spectrum of pristine ZnO showed a peak in the ultraviolet region at 5 eV, while those of the co-doped ZnO samples displayed stronger peaks in the infrared region (near 0.4 eV). The anticancer properties of Tb/Er co-doped ZnO nanoparticles were examined on cervical cancer (HeLa cells) and colon cancer (HCT-116) by using an in vitro MTT assay. The cell viability assay findings indicated a reduction in HeLa and HCT-116 cells after 48 h of treatment of the synthesized samples. The treatment with co-doped ZnO nanoparticles produced chromatin condensation and formation of apoptotic bodies in HCT-166 cells, which indicates that the prepared co-doped ZnO nanoparticles induced programmed cell death in HCT-116 cells. According to these results, it can be concluded that the prepared Tb/Er co-doped ZnO nanoparticles have promising applications in developing new optoelectronic devices and also in treating cervical and colon cancers.

Synthesis and Properties of Eu and Ni Co-Doped ZnS Nanoparticles for the Detection of Ammonia Gas

Zinc sulfide nanoparticles were synthesized successfully via chemical co-precipitation, both in undoped form and co-doped with Europium (Eu) and Nickel (Ni). All prepared samples exhibited cubic zinc blende structure as confirmed by X-ray diffraction (XRD). The average particle size ranged from 3 to 6 nm for both pure and (Eu, Ni) co-doped ZnS, with no alteration in the crystal structure due to Eu and Ni co-doping. However, increasing the Ni dopant concentration (0, 2, 4, & 6 at%) while maintaining a constant Eu concentration (4 at%) led to an enhancement in the crystallite size. This was further validated by transmission electron microscopy (TEM), which showed particle sizes consistent with the XRD findings (3–5 nm). Microscopic analysis via scanning electron microscopy and TEM revealed spherical agglomerated morphology for the (Eu, Ni) co-doped nanoparticles. Energy-dispersive X-ray spectroscopy spectra confirmed the stoichiometric chemical composition of ZnS: Eu, Ni. Photoluminescence studies demonstrated an increased intensity of green luminescence at 6 at% Ni co-dopant concentration. Moreover, the synthesized samples exhibited promising gas sensing properties, particularly towards ammonia gas, with good selectivity. Notably, both pure and (Eu, Ni) co-doped ZnS nanoparticles showed rapid response and recovery times at room temperature, suggesting their potential applicability in gas sensing applications.

ZnAl2O4:Er3+ Upconversion Nanophosphor for SPECT Imaging and Luminescence Modulation via Defect Engineering.

This work reports an "all-in-one" theranostic upconversion luminescence (UCL) system having potential for both diagnostic and therapeutic applications. Despite considerable efforts in designing upconversion nanoparticles (UCNPs) for multimodal imaging and tumor therapy, there are few reports investigating dual modality SPECT/optical imaging for theranostics. Especially, research focusing on in vivo biodistribution studies of intrinsically radiolabeled UCNPs after intravenous injection is of utmost importance for the potential clinical translation of such formulations. Here, we utilized the gamma emission from 169Er and 171Er radionuclides for the demonstration of radiolabeled ZnAl2O4:171/169Er3+ as a potent agent for dual-modality SPECT/optical imaging. No uptake of radio nanoformulation was detected in the skeleton after 4 h of administration, which evidenced the robust integrity of ZnAl2O4:169/171Er3+. Combining the therapeutics using the emission of β- particulates from 169Er and 171Er will be promising for the radio-theranostic application of the synthesized ZnAl2O4:169/171Er3+ nanoformulation. Cell toxicity studies of ZnAl2O4:1%Er3+ nanoparticles were examined by an MTT assay in B16F10 mouse melanoma cell lines, which demonstrated good biocompatibility. In addition, we explored the mechanism of UCL modulation via defect engineering by Bi3+ codoping in the ZnAl2O4:Er3+ upconversion nanophosphor. The UCL color tuning was successfully achieved from the red to the green region as a function of Bi3+ codoping concentrations. Further, we tried to establish a correlation of UCL tuning with the intrinsic oxygen and cation vacancy defects as a function of Bi3+ codoping concentrations with the help of electron paramagnetic resonance (EPR) and positron annihilation lifetime spectroscopy (PALS) studies. This study contributes to building a bridge between nature of defects and UC luminescence that is crucial for the design of advanced UCNPs for theranostics.