Dopant Ions Research Articles

Zinc-doped phosphate coatings for enhanced corrosion resistance, antibacterial properties, and biocompatibility of AZ91D Mg alloy

Magnesium and its alloys have been foreseen as promising bone-implant owing to good biocompatibility, high strength, mechanical properties, and biodegradability to replace the conventional bio-metals (Titanium, stainless-steel, Co-Cr alloys) in orthopedic applications. However, high corrosion rate and high degradation rates adversely effects like abrupt evolution of H2 gas and localized alkalization in a physiological environment limit its medical applications. To overcome these issues, phosphate-based surface coating is developed on Mg-alloy to resist the high biodegradation and corrosion rate utilizing magnesium substrate as source of magnesium ion through a single-step hydrothermal process. Controlling the fast corrosion rate and localized alkalization would reduce the antibacterial character of magnesium-based implants therefore, the simple phosphate-based coatings has been induced by doping it with zinc ions due to its physiological tolerance and excellent antibacterial efficacy. The doping of zinc ions may provide a sustained drug-free antibacterial characteristic for potential application in orthopedics. The synthesized phosphate-based coating was characterized using advanced techniques like Scanning Electron Microscopy, X-ray Diffraction, and wettability test, followed by comprehensive electrochemical testing to assess its corrosion behavior. The in vitro immersion test in simulated body fluid (SBF) indicates that deposition of phosphate and zinc doped phosphate coatings reduces the degradation rate consequently minimized the fast dissolution of Mg2+ ions and OH- in physiological environment. Additionally, cytotoxicity and biocompatibility were evaluated using Alamar Blue and live/dead assays on the MC3T3-E1 mouse osteoblast cell line. These assays demonstrated good cell viability, indicating the coatings possess favorable cytocompatibility and support cellular metabolic activity.

Upconversion and Downshifting Luminescence from KSrVO4:Er3+ Nanophosphor with Judd-Ofelt Parameters.

This study investigates the synthesis and characterization of KSrVO4 phosphors doped with Er3+ ions using combustion synthesis route by using urea as a fuel. X-ray diffraction analysis confirmed the orthorhombic phase and nano-scale crystallite size of around 21nm, while transmission electron microscopy showed spherical and rod-shaped morphologies. The studies detected upconversion emission spectra at 526, 542 and 643nm, representing green and red transitions under 980nm excitation. Downshifting emissions under 350nm excitation revealed peaks at 492, 544 and 680nm. The critical quenching concentration was 2.5mol%, resulting from dipole-quadrupole interactions among dopant ions. The direct and indirect optical band gaps were calculated as 3.61 and 3.41eV, respectively. The calculated chromaticity coordinates and color correlated temperature values of the phosphor surpassed 5000K, suggesting its viability for cool LED applications. These findings emphasize KSrVO4:Er3+ as a promising greenish component in white LEDs and a potent upconverting luminescence material for bio-imaging and photovoltaics.

Cr-induced structural phase transformation in sputter deposited poly-AlN thin film from wurtzite to rocksalt structure and their effect on the optical properties

We report Cr doping-induced structural phase transformation (PT) in sputter-deposited polycrystalline-AlN thin film from wurtzite (w) to rocksalt (r) structure. Rietveld analysis shows that the steady substitution of Al ions by Cr ions in the w-AlN lattice distorts and compresses the wurtzite lattice along the c-axis. The chemical pressure exerted in the w-AlN lattice by the compression from the doped Cr ions causes the PT, similar to the high-pressure-induced PT in AlN. Post the PT, the r-Al1-xCrxN thin film continues to exhibit compressive residual stress, indicating that such sustained stress may also play a role in stabilizing the metastable r-Al1-xCrxN phase. The structural distortion and the PT also affected the optical absorption characteristics of the w-Al1-xCrxN thin films. The w-Al1-xCrxN exhibit a direct inter-band transition and the band gap (Eg) decreases from ∼ 6.06 eV for pure w-AlN to ∼ 4.15 eV for w-Al0.73Cr0.27N. After the PT, the r-Al0.61Cr0.39N thin film, on the other hand, exhibits an indirect inter-band transition with an Eg of ∼ 1.84 eV. In addition to the change in Eg, a prominent defect band appears at ∼ 4 eV at low Cr% and another band appears at ∼ 0.98 eV at higher Cr%.

A study on the improvement of ion conductivity of lithium aluminum titanium phosphate-based solid-state electrolyte by the addition of divalent cations

AbstractNa like super ionic conductors (NASICON)-structure Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte have attracted attention as high ion conductivity and chemical stability. The M1–M2 voids between the TiO6 octahedra and PO4 tetrahedra in a Li1.3Al0.3Ti1.7(PO4)3-based solid electrolyte is a major path for lithium-ion conduction, and it can be widened to increase lithium-ion conductivity by doping. In this study, divalent ions are doped into the Li1.3Al0.3Ti1.7(PO4)3-based electrolyte and widened ion-conduction path and improved ion conductivity. Making doped Li1.3Al0.3Ti1.7(PO4)3 samples starts with melting, then transformed into glass, pulverized, and then subjected to uniaxial compression molding and sintering, after which they are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and their impedance resistances were measured. The LiTi2(PO4)3 is generated by thermal treatment and crystallized to form an electrolyte whose lattice parameter values depend on the dopant ion and its content, with each divalent ion distorting the lattice and the M1–M2 bottleneck structure differently. Only Mg2+ doping led to a structural change that increases Li-ion conductivity to 1.55 × 10−3 S/cm at 5 mol% of magnesium ion, with the observed threefold increase in conductivity compared to the 4.73 × 10−4 S/cm ion conductivity of LATP ascribable to a widening of the ion-conduction path. Overall, doping an LATP-based solid electrolyte with an appropriate divalent cation is a promising way of improving performance in a manner that has various applications.

(Invited) Core-Multi-Shell Design: Unlocking Multimodal Capabilities in Lanthanide-Based Nanoparticles

The remarkable optomagnetic properties of the lanthanides (Ln) make Ln-based materials ideal for biomedical applications, including diagnostic (e.g., imaging, nanothermometry) and therapeutic (e.g., drug delivery, photodynamic therapy) approaches. This is due the unique electronic properties of the f-elements allowing for upconversion and near-infrared emission under near-infrared excitation as well as high magnetic moments. Yet, challenges remain, including low emission intensity and efficiency of small nanoparticles (NPs), and reliable, fast synthesis routes. As material chemists, we tackle these challenges with new designs of Ln-NPs by chemically controlled synthesis, application-oriented surface chemistry, and understanding of structure-property-relationships. We developed a straightforward and rapid microwave-assisted synthesis approach towards core-multi-shell Ln-NPs. Careful architecture design and choice of RE3+ dopant ions allow to tune the optical properties of the resultant nanoparticles, i.e., upconversion and near-infrared emission. This presentation will shed light on recent results with respect to microwave-assisted synthesis of Ln-NPs as well as structural and optomagnetic properties, seeking biomedical application.For instance, multimodal bioimaging probes merging optical imaging, magnetic resonance imaging (MRI), and X-ray computed tomography (CT) capabilities have attracted considerable attention due to their potential biomedical applications. This includes nanoparticles that combine upconverting Er3+/Yb3+ and magnetic NaDyF4 for optical/T2-weighted MRI/CT multimodal capabilities. A known drawback of multimodal probes that merge the upconverting Er3+/Yb3+ ion pair with magnetic Dy3+ ions for T2-weighted MRI is the loss of upconversion emission due to Dy3+ poisoning. The synthesis of controlled nanoparticle architectures with tuned inner NaGdF4 shell thicknesses separating Dy3+ and Er3+/Yb3+ allow to shed light on this distance-dependent loss of upconversion due to Yb3+ → Dy3+ energy transfer. As a result, the Ln-NP architecture was tuned to not only restore but enhanced the upconversion emission. In addition to multimodal imaging, Ln-NPs are promising candidates for application in nanothermometry due to the distinct, temperature-induced changes in their spectral features. We seek the development of novel Ln-NP nanothermometers for new opportunities in the near-infrared biological transparency windows (1000 to 2000 nm), by doping RE3+ ions, such as Er3+ and Tm3+ as well as unconventional Pr3+, into core-multi-shell lanthanide-based nanoparticles.

Cu/F Dual-Doping on the Ni–Mn Based Layered Oxide As Cathode Material for Sodium-Ion Batteries

As demands for energy storage are ever-increasing, sodium ion batteries (SIB) have been widely conducted for superior electrochemical performance and reduction in cost compared to lithium ion batteries (LIBs), one of the most commonly used energy storage devices nowadays. Among all the parts in batteries, cathode materials play a crucial role with regard to performance. Here, layered transition metal oxides (LTMOs) (NaxTMO2, TM = Cu, Mn, Fe, Ti, Co, Cr, Ni, etc.) have kept catching researchers’ eyes due to their mature developments in commercial LIBs over decades.P2-type Ni/Mn-based LTMOs (such as Na0.67Ni0.33Mn0.67O2, NNMO) exhibit high theoretical specific capacity (~173 mAh g− 1) with environmentally friendly and cheap elements. However, they show limited stability upon charging over 4.2 V, directly restricting their energy density and lowering operating voltage. Besides, disadvantages such as poor rate performance and air/moisture sensitivity are remaining improvements for commercialization. Hence, our study mainly focuses on improvements for shortages of NNMO by applying a facile cation-and-anion co-doping strategy. Via transition metal Cu ion doping, the cycling stability of NNMO can be improved without sacrificing too much capacity, and the air stability can also be improved. In addition, F doping to replace oxygen can further enhance the structural stability and increase the rate performance by modifying interlayer spacing of the layered structure. A facile sol-gel method with heat treatment is used to synthesize cation-and-anion co-doped NNMO. The material characterization shows successful synthesis after cation and anion doping. In addition, the long cycle test shows that capacity retention increases from ~50% to ~90% over 100 cycles after Cu doping. The specific discharge capacity also increases from ~110 mAh/g to ~130 mAh/g at 0.1C with a slight increase in cycle retention from ~75% to ~77% after F doping. Also, the capacity at 20C could be maintained at ~50 mAh/g, around 45% of the initial capacity at 0.1C. The detailed charge storage mechanism will be studied by applying operando X-ray absorption spectroscopy and ex-situ X-ray photoelectron spectroscopy. As for the moisture sensitivity part, the XRD spectra indicate that no noticeable structural changes or impurity formation occurred after air exposure for one month, showing good air stability. Furthermore, operando XRD is conducted to confirm structural reversibility during charging and discharging.In summary, by applying a simple Cu/F co-doping strategy, Na0.67Ni0.13Cu0.20Mn0.67O2-xFx exhibits sufficient cycle stability for over 100 cycles as well as excellent rate capability even at a high current density of 20C, which proves itself a promising candidate as high-performance cathode material in SIBs. In addition, the cheap and environmentally friendly elemental usage (Ni, Mn and Cu) and air-stability enhancement also increase possibility of this material for large-scale energy storage application in industry.

Metal ions guide the production of silkworm silk fibers

Silk fibers’ unique mechanical properties have made them desirable materials, yet their formation mechanism remains poorly understood. While ions are known to support silk fiber production, their exact role has thus far eluded discovery. Here, we use cryo-electron microscopy coupled with elemental analysis to elucidate the changes in the composition and spatial localization of metal ions during silk evolution inside the silk gland. During the initial protein secretion and storage stages, ions are homogeneously dispersed in the silk gland. Once the fibers are spun, the ions delocalize from the fibroin core to the sericin-coating layer, a process accompanied by protein chain alignment and increased feedstock viscosity. This change makes the protein more shear-sensitive and initiates the liquid-to-solid transition. Selective metal ion doping modifies silk fibers’ mechanical performance. These findings enhance our understanding of the silk fiber formation mechanism, laying the foundations for developing new concepts in biomaterial design.

The Impact of Boron Compounds on the Structure and Ionic Conductivity of LATP Solid Electrolytes.

The increasing demand for safe and high-energy-density battery systems has led to intense research into solid electrolytes for rechargeable batteries. One of these solid electrolytes is the NASICON-type Li1+xAlxTi2-x(PO4)3 (LATP) material. In this study, different boron compounds (10% B2O3 doped, 10% H3BO3 doped, and 5% B2O3 + 5% H3BO3 doped) were doped at total 10 wt.% into the Ti4+ sites of an LATP solid electrolyte to investigate the structural properties and ionic conductivity of solid electrolytes using the solid-state synthesis method. Characterization of the synthesized samples was conducted using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The XRD patterns of the boron-doped LATP (LABTP) samples show that the samples have a rhombohedral phase with space group R3¯c together and low amounts of impurity phases. While all the LABTP samples exhibited similar ionic conductivity values of around 10-4 S cm-1, the LABTP2 sample doped with 10 wt.% H3BO3 demonstrated the highest ionic conductivity. These findings suggest that varying B3+ ion doping strategies in LATP can significantly advance the development of solid electrolytes for all-solid-state lithium-ion batteries.

Achieving high acousto-optic properties and low thermal expansion anisotropy in TeO2 single crystals via Mn-doping

TeO2 single crystals have been widely used in military and civilian fields as an excellent acousto-optic (AO) material. However, due to its significant thermal expansion anisotropy and poor mechanical properties, there is a considerable risk of cracking, which hinders further applications in the AO field. Here we successfully grew a TeO2 single crystal doped with 2 % Mn4+ ions (TeO2:0.02Mn4+). This single crystal demonstrates excellent characteristics, including lower acoustic attenuation (α) and larger refractive index values. In addition, it also possesses a higher AO figure of merit (M2) of 832 × 10−15 s3/kg than TeO2 single crystal (∼793 × 10−15 s3/kg). More importantly, the TeO2:0.02Mn4+ single crystal demonstrates low thermal expansion anisotropy within a temperature range of up to 450 °C, indicating a greater practical value. The high AO performance may be attributed to manganese ion doping. The doping of Mn increased the refractive indices by enhancing the electronic polarizability and achieved lower acoustic attenuation by improving mechanical properties. Combining the results of elastic modulus and Raman spectroscopy analysis, it is observed that manganese doping optimizes crystal structure disorder, thus improving the issue of thermal expansion anisotropy. These results indicate that this TeO2:0.02Mn4+ single crystal has significant potential in designing and manufacturing AO devices.

Vanadium as a Ti-like mediator boosting electronic transmission in Fe-based MOFs for photocatalytic sterilization

Efficient metal–organic frameworks (MOFs) photocatalytic bactericidal catalysts are urgently needed in water purification. Herein, a Fe-MOF (MIL-88B-NH2(V1Fe5) with promoted electron transport was achieved by vanadium (V) ions doping and V/Fe ratio optimization, showing excellent photocatalytic bactericidal activity against E. coli under visible light irradiation (99.92%). The efficient antibacterial mechanism, V as a Ti-like mediator boosting electronic transmission in MIL-88B-NH2(V1Fe5), was revealed by its band structure, transient photocurrent, electrochemical impedance spectroscopy, and scavenger quenching experiments. The enhancement of photocatalytic bactericidal performance of Fe-MOFs by V–ion-doping was confirmed by two other Fe-MOFs, MIL-53-NH2(V1Fe5) and MIL-101-NH2(V1Fe5), with the same metal ions and ligands, both of which have higher performance than the corresponding undoped MOFs. Among them, MIL-88B-NH2(V1Fe5) exhibits the highest photocatalytic bactericidal activity due to its suitable metal clusters ([M(μ 3-O)] cluster) and topological structure (three-dimensional rhomboid network structure). This work demonstrated the amplification effect of V ion doping on electron transport in Fe-MOFs photocatalysts.

Divalent manganese (Mn2+, 3d5) charge transfer energies and vacuum-referred binding energies in inorganic compounds

Ongoing efforts to develop a predictive model governing the host-referred binding energies (HRBEs) and vacuum-referred binding energies (VRBEs) of transition metal dopants in inorganic host compounds are stymied by a lack of cross-compound data sets that capture transitions between the dopant ions and the valence and conduction bands of the hosts. Herein, we have compiled data consistent with Mn2+ charge transfer processes in 53 different compounds, spanning fluorides, oxides, chlorides, bromides, and nitrides. By assigning these transitions to Mn2+ → conduction band metal-to-metal charge transfer and combining these energies with the binding energies of electrons in the valence and conduction bands of the various hosts, we have calculated the HRBEs and VRBEs of the Mn2+ ion across a range of compounds. We show that variations in the Mn2+ VRBE are small relative to the variations in the VRBE of the valence and conduction bands, which manifests an approximately linear relationship between the Mn2+ HRBE and the bandgap energy of host compounds. We investigated the relationship between the Mn2+ VRBE and the various structures of the host compounds and showed that the chemical shift experienced by the Mn2+ ion depends on the electronegativity of the ligand, the Mn2+ coordination, and the Mn-ligand bond lengths in a predictable manner.

Green mediated approach to investigate the optical, structural, photocatalytic, magnetic and dielectric properties of Cr3+ doped ZnO nanoparticles for energy applications

Herein, the influence of Cr3+ dopant on the structural, morphological, optical, photocatalytic, dielectric and magnetic properties of ZnO was investigated for various applications. Pure ZnO and Cr3+ doped ZnO nanoparticles were synthesised by green mediated approach. The synthesised nanoparticles examined by using XRD, SEM, EDX, FTIR, PL, UV–Vis spectroscopy, dielectric and magnetic analysis. XRD confirmed the wurtizte hexagonal structure of synthesised samples and also revealed that the Cr didn't alter the structure of host ZnO. The FTIR analysis revealed the presence of Cr ions in ZnO structures. Doping of Cr ions improved the optical absorbance of ZnO and the optical band gap showed the blue shift with increasing concentration of Cr. The synthesised Cr doped nanoparticles show the outstanding photocatalytic efficiency under solar irradiation against MG pollutant dye. The dielectric constant (ε) improves and dielectric loss (tan (δ)) reduces at lower frequencies with increasing content of Cr. The AC conductivity for doped nanoparticles showed the increasing trend, especially for 4.5 % Cr doped ZnO nanoparticles. The ferromagnetic behavior at room temperature of Cr doped ZnO nanoparticles confirmed by VSM. The obtained results from all investigations make the Cr doped ZnO samples a potential choice for various applications such as, spin based electronic devices and energy storage devices.

Effect of modulating monovalent ion doped on A-site high-entropy perovskites

High-entropy materials constitute solid solutions composed of five or more elements. This complex and diverse composition endows the materials with unique physical and chemical properties, presenting immeasurable value in material design. Despite such potential applications, the composition design still has deficiencies, and the influence mechanism of elements remains a research gap. In this work, a series of new high-entropy perovskites (La0.5X0.5)0.2(Ce0.5X0.5)0.2Ba0.2Sr0.2Ca0.2TiO3 (where X = Li, Na, K) were designed and synthesized. We systematically studied their phase structures, microscopic morphologies, as well as dielectric and ferroelectric properties. Notably, novel findings are reported. Specifically, (La0.5Li0.5)0.2(Ce0.5Li0.5)0.2Ba0.2Sr0.2Ca0.2TiO3 ceramics exhibit excellent breakdown field strength (Eb = 135 kV cm−1) and minimal leakage currents in 10−7–10−6 A cm−2. Moreover, the designed ceramics display exceptional dielectric constant (εr = 5 × 104) and saturation polarization (Ps = 2.8 μC cm−2) properties. These findings introduce novel insights into designing high-entropy ceramic components, enabling the customization of new dielectric and ferroelectric properties by manipulating doped monovalent ions.

Cobalt-iron Co-doped ammonium phosphomolybdate for electrocatalytic oxygen evolution in acidic electrolyte

In this study, we investigate the performance of cobalt-iron co-doped phosphomolybdate (CoFe–PMo) as an efficient electrocatalyst for oxygen evolution reaction (OER) in acidic electrolyte. We demonstrate that the introduction of cobalt and iron ions into the phosphomolybdate structure enhances its catalytic activity towards OER. The electrochemical measurements reveal that CoFe–PMo exhibits remarkable stability and improved catalytic activity compared to the undoped amminium phosphomolybdate. The overpotential for OER is only 223 mV at 10 mA cm−2, which is even smaller than that of IrO2.The durable tests maintain its performance over 40 h electrolysis period that the current barely drops. This enhanced performance is attributed to the internal redox between doped cobalt-iron ions and Mo ions in PMo, which promotes the charge transfer and enhances the active sites for OER. The results suggest that CoFe–PMo is a promising catalyst for efficient water splitting in acidic electrolyte, highlighting the potential of cobalt-iron co-doped ammonium phosphomolybdate as a cost-effective and durable electrocatalyst for water splitting for H2 energy in acidic electrolytes.

TL, EPR, and optical properties of undoped and Eu-, Ce-, Tb-, Sm-, Cu-, Mn-, and Li- doped MgSiO3 phosphors, synthesized by sol-gel combustion technique

Polycrystalline MgSiO3 samples, undoped or doped with rare earth- (Eu, Tb, Ce, Li, Sm), transition- (Mn and Cu), and alkali metal- (Li) elements, were prepared by the sol-gel combustion method and characterized by thermoluminescence, electron spin resonance, and optical properties. Enstatite and protoenstatite phases are observed in undoped and doped MgSiO3. Better TL results have been observed for phosphors doped with Tb, Ce, and Li (0.5 % mol). Fading experiments and the GCD method have been performed. EPR signals of gamma-irradiated phosphors indicate the formation of radiation-induced defect centers. Cu-doped MgSiO3 shows an unusual feature of the Cu2+ ion. The Cu2+ ion occupies a tetragonally compressed octahedral site, presenting an unconventional attribute. Optical bandgap value Eg is higher for the Ce, Tb, Mn, Li, Sm, and Cu-doped MgSiO3 phosphors. Ce, Li, and Tb dopant ions were found suitable for the MgSiO3 sample regarding its thermoluminescent response and its possible application in radiation dosimetry.

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.

Controlled growth of single-walled carbon nanotubes with narrow diameter distribution and high areal density on Mn-doped ZrO2-supported Fe catalyst

Single-walled carbon nanotubes (SWCNTs) with a narrow diameter distribution and high areal density hold great promise for a variety of applications, particularly in advanced electronics and biomedical devices. This study utilizes Mn ion doping as a strategic approach both to stabilize the ZrO2-supported Fe catalyst and regulate lattice oxygen release, thereby facilitating the growth of SWCNTs with high areal density and a narrow diameter distribution. The ZrO2-supported Fe catalyst was meticulously dispersed on Si/SiO2 (300 nm) substrates through the optimization of spin-coating speed and solvent viscosity, aiming to enhance the dispersion and uniformity. Investigation into the precise control over the Mn ion content was conducted to regulate the structure and stability of the Mn-doped ZrO2-supported Fe catalyst. Mn ions perform a dual role: they maintain a higher proportion of ZrO2 in the monoclinic phase, which in turn alleviates the monoclinic-tetragonal phase transition during chemical vapor deposition (CVD) growth. Concurrently, the conversion of Mn3+ to Mn4+ ions captures the lattice oxygen released during the formation of zirconium transition oxides. Additionally, first-principles simulations have confirmed the stabilizing impact of Mn ions on the catalyst, which reduces aggregation and maturation, ultimately resulting in a more concentrated diameter distribution of as-grown SWCNTs. This approach has successfully achieved the controlled growth of high areal density SWCNTs with a diameter distribution of 1.73 ± 0.08 nm.

Study the Effect of Ion Doping on ZnO Nanostructures for Room Temperature NH3 Gas Sensor

We investigated the impact of doping ion type on the performance of a ZnO-based ammonia gas sensor to show the capability of these ions to achieve high-performance gas sensing at room temperature. A sol-gel method was used to synthesize both doped and undoped ZnO nanostructures, while the gas sensor device was made by casting ZnO onto a glass substrate for a uniform thin film. Then Al electrodes were attached to the film. The characterization was carried out via field-emission scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, UV–vis, Pl luminescence, Brunnauer-Emmett-Teller, I-V characteristic, and gas sensor setup device. PL measurement shows an increase in green emission spectra with Ba ion shifting the peaks from VO to VO+ and VO+ to VO++ states. The gas sensor test at room temperature greatly enhances performance for certain ions. The Ba ions greatly influence gas sensor performance, increasing the response to 24 compared to 5 for undoped ZnO. The room-temperature enhancement achieved by the Ba ions could open the way to investigate more effective dopants for NH3 gas sensors.

Bimolybdate single crystals codoping with trivalent ytterbium and erbium ions for high-stable and high-sensitive optical thermometry

Replacing conventional powder polycrystalline materials with crystalline materials is an effective strategy to improve the sensing sensitivity, responsiveness, and anti-interference capabilities of the fluorescence intensity ratio (FIR) based optical temperature sensing techniques. In this work, Yb3+/Er3+ codoped bimolybdate single crystals, NaBi(MoO4)2 (NBM) with different Er3+ ion doping concentrations, were grown by the Czochralski method, in which is expected to be used for optical temperature sensing applications. The structure of the crystals was fully characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM). Under 980 nm laser excitation, the crystals demonstrated notable green and slight red upconversion (UC) emissions, and the mechanism of UC luminescence was thoroughly investigated. The luminescence intensity was found to be contingent upon the doping concentration, which gradually decayed with increase of Er3+ ions. The optical temperature sensing performance of Yb3+/Er3+ codoped NBM single crystals was evaluated by the FIR technique based on the thermally coupled level of Er3+ ions (2H11/2/4S3/2). The experimental findings revealed that the 10 at% Yb3+, 10 at% Er3+: NBM crystal exhibited highest sensor sensitivity among the synthesized crystals, with a maximum absolute sensitivity of approximately 1.22 % K−1 at 510 K. Furthermore, the temperature sensing characteristics of the crystals appeared to be dependent on the doping concentration of Er3+ ions. In summary, the Yb3+/Er3+ codoped NBM single crystal showcased excellent sensor sensitivity and held considerable promise as materials for optical temperature sensing applications.

Development of blue-light absorbing silicate glasses through codoping with TiO2, CeO2, Fe2O3, and Bi2O3

The high energy of blue light (approximately 460 nm) emitted from display components may lead to ocular pathologies. Therefore, the development of glass compositions resistant to blue light is crucial. In this study, TiO2, CeO2, Fe2O3, and Bi2O3 were doped into a Na2O–CaO–Al2O3–SiO2 glass composition. The required properties of the glasses are to reduce the transmittance at 460 nm (T460) to less than 50 %, while maintaining high transmittance at longer wavelengths (T550 > 70 %, and T700 > 80 %). The glasses were prepared using the conventional melt-quench method. The cast glasses were analyzed using a UV–visible spectrophotometer to obtain the transmittance spectra ranging from 200 to 800 nm. The reflectance (R) of glass powder compacts was measured using a spectrophotometer equipped with a reflectance integrating sphere. This data was then used to derive the Kubelka-Munk function, F(R), which can display absorption peaks. After deconvolution, the contributions of each doping ion were obtained. Based on the experimental results, the dopant-free glass is colorless, with a cutoff wavelength (λc) of 213 nm and T460/T550/T700 of 90/91/92 %. All four types of dopants increase λc and decrease the transmittance. The combination of Ti–Ce–Fe–Bi dopants is relatively more likely to meet the transmittance requirement. The contributions of Ti4+, Ce4+, Ce3+, Fe3+, and Bi3+ ions to the UV-blue absorption as well as their potential redox tendencies are discussed. Raman analysis reveal that the dopants mainly act as network modifier in the glass structure, increasing the number of non-bridging oxygen. This effect also contributes to the red shift at the absorption edge.