Gd Doping Research Articles

Photoluminescence properties of Sr3Y2(BO3)4: Eu3+ phosphor codoped with Gd3+ and La3+ under ultraviolet excitation

Sr3Y2 (BO3)4: Eu3+ phosphor codoped with Gd3+ and La3+ was generated using the solid state method, and XRD and fluorescence spectrum researched the structure and luminescence properties. The strongest excitation peak of Sr3Y2 (BO3)4:Eu3+ is in the near ultraviolet region of 394 nm, which comes from the 7F0 → 5L6 transition of Eu3+. With the stimulation of 394 nm ultraviolet-light, the strongest emission of Sr3Y2 (BO3)4:Eu3+ phosphor is a red light with a wavelength of 618 nm. It is produced by the transition of 5D0 → 7F2 of Eu3+. The optimum preparation temperature is 1000°C, and the doping amount of Eu3+ is 5% (mol). The doping of Gd3+ and La3+ greatly enhanced the luminescent intensity of Sr3Y2 (BO3)4:Eu3+ phosphor, and the doping of 20% (mol) was suitable.

Enhanced Magnetic Properties of Gd-Doped ZnO by Varying the Gd Concentration via Co-Sputtering Technique

This study reports on the effect of Gd concentrations on the properties of Gd-doped ZnO films. The films were prepared using co-sputtering method at room temperature. Characterization tools such as X-ray diffraction (XRD), atomic force microscopy (AFM), and vibrating sample magnetometer (VSM) were used to analyze the properties of the prepared films. XRD results observed that all the films are well crystalline and designated to the hexagonal wurtzite structure of ZnO with no secondary phases, which confirmed the successful of doping the Gd into ZnO. Topography analysis from AFM discovered the increase of Gd concentrations of Gd-doped ZnO films leads to the increase in grain size and rougher surface of the films. The magnetization of the films effectively depends on the Gd concentrations, which the diamagnetic behavior changed to ferromagnetic behavior upon Gd doping. A film with higher Gd doping concentration is more effective than lower Gd doping in terms of saturation magnetization (Ms), coercivity (Hc) and remanent magnetization (Mr). These findings revealed that optimizing the Gd concentration is very crucial in enhancing the magnetic properties of Gd-doped ZnO films.

Bifunctional reality of Gd doping to boost the photocatalytic H2O2 production of Au/BiVO4

Au/BiVO4 is considered as one of promising composite photocatalytic materials for H2O2 synthesis due to its suitable band structure and exceptional two-electron O2 reduction selectivity. However, the rapid decomposition of H2O2 caused by holes and the slow charge transfer resulting from high Schottky barrier between BiVO4 and Au limit its highly-efficient H2O2 production. In this work, a doping strategy is proposed to solve the above two limitations. Here, as the dopant, Gd is uniformly distributed in BiVO4 crystal, while Au is selectively modified on the electron-rich (010) facets of BiVO4. Consequently, 0.1 wt% Gd-doped Au/BiVO4 photocatalyst is proved to present highest H2O2-production performance with 2.07 mmol/L (AQE = 7.44 %) within 2 h, which is 1.39 times higher than that of Au/BiVO4. The improvement of photocatalytic activity for Au/BiVO4:Gd photocatalyst is mainly attributed to substitution of Gd at Bi-site, which inhibits the decomposition of H2O2, and lowers the Fermi energy level of BiVO4 to match with that of Au, giving rise to fast charge transfer and enhanced two-electron reduction activity of O2. This work provides a new perspective for improving the performance of photocatalyst materials modified by metal cocatalyst.

The effect of Gd on the microstructure and electrochemical properties of Mg-Ni-based alloys

The Mg-Ni-based alloys have been extensively investigated as negative electrode materials in Nickel-Metal Hydride (Ni-MH) batteries. In this work, two Mg-Ni-based samples (Mg71Ni29 and Mg72.6Ni25.3Gd1.1) were prepared by means of melting. The X-ray diffraction (XRD), scanning electron microscope (SEM), galvanostatic charging/ discharging and other electrochemical measurements were used for the investigation. The results show that the Mg71Ni29 and Mg72.6Ni25.3Gd1.1 alloys include the characteristic peaks of Mg2Ni and the less strong characteristic peaks of Mg and MgNi2 phases. The diffraction peak of the major phase Mg2Ni of the Mg72.6Ni25.3Gd1.1 alloy is shifted to a small angle and its unit cell volume increases. With the addition of Gd, the alloy electrodes exhibits better cycling stability. After 50 charge/ discharge cycles, the capacity retention rate of the alloy electrode increase from 16% (Mg71Ni29) to 22% (Mg72.6Ni25.3Gd1.1). However, the maximum discharge capacity of the alloy electrode decrease from 134.3 mAh/g (Mg71Ni29) to 91.9 mAh/g (Mg72.6Ni25.3Gd1.1). The Mg72.6Ni25.3Gd1.1 alloy possess lower limiting current density IL and exhibit relatively high corrosion resistance against the alkaline solution. After Gd doping, the charge transfer capacity of the Mg72.6Ni25.3Gd1.1 alloy surface is increased.

Photocatalytic degradation of ciprofloxacin by Gd-Co/g-C3N4 under low-power light source: Degradation pathways and mechanistic insights

Ciprofloxacin hydrochloride (CIP) is remained in the natural environment. Photocatalysis is a promising technology for removing hard-to-degrade pollutants from water. For this purpose, we constructed a three-dimensional porous structure of graphitic-phase carbon nitride (3D g-C3N4) and doped rare earth element Gd and metal Co into 3D g-C3N4 to form a photocatalyst (Gd-Co/CN). We conducted photocatalytic experiments to evaluate its photocatalytic activity with CIP as the target pollutant. Experimental results showed that Gd-Co/CN had the best photocatalytic degradation of CIP under a 30 W LED lamp. The increase in photocatalytic activity is mainly attributed to the doping of Gd and Co expanding the specific surface area of 3D g-C3N4, and providing more reaction sites for photocatalytic reactions. Gd-Co/CN enhances O2 adsorption and activation and generates radicals (O2− and h+), allowing efficient degradation of CIP under low-power light sources. Furthermore, Gd-Co/CN also showed excellent stability and reusability in cycling experiments. This study explored the degradation pathways and mechanisms of CIP by using ultra-high-performance liquid chromatography and mass spectrometry (HPLC-MS) and density functional theory (DFT). It provides a more energy-efficient and environmentally friendly method for the treatment of antibiotic wastewater.

Gd Doping at the Co/Pt Interfaces to Induce Ultrafast All-Optical Switching

Gd Doping at the Co/Pt Interfaces to Induce Ultrafast All-Optical Switching

Harmonic response of Gd-doped Mn-ferrite nanoparticles under AC magnetic field and optimization of Gd doping for MPI applications

This study synthesized Gd-doped Mn-ferrite nanoparticles for magnetic particle imaging (MPI) applications with doping levels (x) of 0, 0.05, 0.07, and 0.10. Analyses using X-ray diffraction measurements unequivocally confirmed the presence of a spinel-type crystal structure in the synthesized particles and X-ray absorption fine-structure spectroscopy confirmed the incorporation of Gd atoms in place of Mn within the crystal lattice. Magnetization and harmonic measurements under an AC magnetic field revealed that particles with a high initial permeability and low coercivity showed a high response intensity. Notably, particles possessing a Gd doping level of x = 0.07 displayed the highest response and were considered promising as MPI materials.

Effects of V and Gd doping on novel positive colossal electroresistance and quantum transport in PbPdO2 thin films with (002) preferred orientation.

In this work, PbPd0.9V0.1O2 and PbPd0.9Gd0.1O2 thin films with (002) preferred orientation were prepared using a pulsed laser deposition technique. The temperature dependence of resistivities ρI(T) was investigated under various applied DC currents. Colossal electroresistance (CER) effects were found in PbPd0.9V0.1O2 and PbPd0.9Gd0.1O2. It was found that the positive CER values of PbPd0.9V0.1O2 and PbPd0.9Gd0.1O2 reach 3816% and 154% for I = 1.00 μA at 10 K, respectively. In addition, the ρI(T) cycle curves of PbPd0.9V0.1O2 and PbPd0.9Gd0.1O2 thin films showed a critical temperature similar to that of PbPdO2 (Tc = 260 K). Particularly, charge transfer between O1- and O2- was confirmed by in situ XPS. Additionally, based on first-principles calculations and internal electric field models, the CER and magnetic sources in PbPd0.9V0.1O2 and PbPd0.9Gd0.1O2 can be well explained. Finally, it was found that thin film samples doped with V and G ions exhibit weak localization (WL) and weak anti-localization (WAL) quantum transport properties. Ion doping leads to a transition from WAL to WL. The study results indicate that PbPdO2, one of the few oxide topological insulators, can exhibit novel quantum transport behavior after ion doping.

Influence of Gd and Ni doping on the structural, morphological, and magnetic properties of M-type calcium hexaferrite

In this study, our aim was to synthesize Gd–Ni doped M-type calcium hexaferrites using a solid-state reaction method.

Influence of gadolinium doping on structural, optical, and electronic properties of polymeric graphitic carbon nitride.

Polymeric graphitic carbon nitride (gCN) materials have received great attention in the fields of photo and electrocatalysis due to their distinct properties in metal-free systems with high physicochemical stability. Nevertheless, the activity of undoped gCN is limited due to its relatively low specific surface area, low conductivity, and poor dispersibility. Doping Gd atoms in a gCN matrix is an efficient strategy to fine-tune its catalytic activity and its electronic structure. Herein, the influence of various wt% of gadolinium (Gd) doped in melon-type carbon nitride was systematically investigated. Gadolinium-doped graphitic carbon nitride (GdgCN) was synthesized by adding gadolinium nitrate to dicyandiamide during polymerization. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed that the crystallinity and the morphological properties are influenced by the % of Gd doping. Furthermore, X-ray photoelectron spectroscopy (XPS) studies revealed that the gadolinium ions bonded with nitrogen atoms. Complementary density functional theory (DFT) calculations illustrate possible bonding configurations of Gd ions both in bulk material and on ultrathin melon layers and provide evidence for the corresponding bandgap modifications induced by gadolinium doping.

Tailoring the electrocatalytic properties of novel microwave synthesized CuNd(2−x)GdxO4 nanoparticles for efficient total water splitting in alkaline media

CuNd(2−x)GdxO4 nanoparticles synthesized via microwave method as efficient OER and HER catalysts require low overpotentials exhibiting remarkable stability. Gd doping enhances charge transfer leading to optimized electrocatalysis.

In situ evolution of bulk-active γ-CoOOH with immobilized Gd dopants enabling efficient oxygen evolution electrocatalysis.

Promoting the in situ reconstruction of transition metal (TM)-based precatalysts into low-crystalline and well-modified TM (oxy)hydroxides (TMOxHy) during the alkaline oxygen evolution reaction (OER) is crucial for enhancing their catalytic performances. In this study, we incorporated gadolinium (Gd) into a cobalt hydroxide precatalyst, achieving a deep reconstruction into cobalt oxyhydroxide (γ-CoOOH) while retaining the incorporated Gd during the activation process of the alkaline OER. The unconventional non-leaching Gd dopants endow γ-CoOOH with reduced crystallinity, increasing the exposure of electrolyte-accessible Co atoms and enhancing its bulk activity. Furthermore, the modulation of the electronic structure of γ-CoOOH substantially boosts the intrinsic activity of the active Co sites. As a result, when supported on nickel foam, the catalyst exhibits remarkable alkaline OER performance, achieving a current density of 100 mA cm-2 at a low overpotential of approximately 327 mV. Notably, an ultrahigh current density of 1000 mA cm-2 is robustly maintained for 5 days, highlighting its immense potential for practical applications in large-scale hydrogen production.

Lanthanide element variation in rare earth doped ceria – FeCo2O4 dual phase oxygen transport membranes

The increased interest in dual-phase membrane materials for oxygen separation leads to the continuous optimization of their composition. Rare-earth doped ceria is a promising candidate as the ion-conducting phase in the membrane. Spinel-structured FeCo2O4 was investigated as an electronic conducting phase forming an additional electronic conducting perovskite-structured phase during sintering when combined with Ce1−xLnxO2−δ. The influence of rare-earth lanthanide elements, i.e., Gd and Sm, as well as their concentration, i.e. x = 0.1 and 0.2, on the final phase composition and microstructure as well as its related functional properties in particular oxygen permeation is analyzed. 20 mol.% doping of either Gd or Sm reveals a multi-phase microstructure after sintering. Moreover, segregation of Gd/Sm, iron, and cobalt is found at the ceria-ceria grain boundaries in Ce0.8Sm0.2O2−δ- and Ce0.9Gd0.1O2−δ-based composites. In contrast, 10 mol.% Gd–doping leads to a dual-phase membrane material without the formation of any other phase. In all cases, the percolation threshold is reached at approx. 20 vol% of the electron-conducting phase in the system leading to similar maximum permeation rates determined by the ionic conductivity of the ceria phase.

Enhanced Ca3Co4O9 thermoelectric transport properties through Gd doping based on spin entropy and size effect

Optimising thermoelectric transport properties by controlling carrier concentration and grain size through doping ions is essential for the design of thermoelectric materials. The extra spin entropy can be increased by modulating the Co4+/Co3+ ratio of the sample by doping ions at the Co site to increase the Seebeck coefficient and minimise the competition between the Seebeck coefficient and the electrical conductivity. We have systematically investigated the thermoelectric properties of Gd-doped Ca3Co4−xGdxO9 ceramic materials. The XRD and SEM exhibit that the sample is a single phase; gradually, the grain size became smaller as the amount of Gd doping increased. The XPS and Raman tests determined that Gd doping occurs at the Co site in the [CoO2] layer. Gd doping drives up the sample carrier concentration and increases the conductivity. Concurrently, the spin entropy modulation by Gd doping increased the Seebeck coefficient. The Gd doping introduces point defects while allowing a reduction in grain size, reducing the thermal conductivity by 14 %. The ZT of Ca3Co3.94Gd0.06O9 was the highest with the interaction of electrical and thermal properties, reaching 0.13 at 773 K, an improvement of approximately 44 %.

Effect of Gd doping on phase evolution, mechanical and thermal characteristics of 1La-xGd-2Yb-3.5YSZ solid solutions

Thermal barrier coatings (TBCs) are critical for the reliability and lifespan of aircraft engine turbine blades. In this study, a novel quaternary rare-earth oxide (La2O3, Gd2O3, Yb2O3, and Y2O3) co-doped ZrO2 solid solution, referred to as 1La-xGd-2Yb-3.5YSZ, was synthesized by varying the doping amount of Gd2O3 from 0 to 6 mol. %. The impact of co-doping-induced lattice distortion on the phase composition, high-temperature phase stability, sintering resistance, and mechanical and thermal properties of the solid solution has been explored. It is found that the addition of Gd2O3 stabilizer effectively increased the lattice distortion of the solid solution, which led to improved phase stability and sintering resistance, enhanced mechanical properties, and low thermal conductivity. Our findings highlight the promising properties of the 1La-xGd-2Yb-3.5YSZ solid solution, making it an attractive candidate for TBC materials.

Effect of Gd addition on the microwave absorption properties of FeSiAl composite

FeSiAl-xGd composites were fabricated by vacuum sintering technique in this paper. The electromagnetic parameters of the composites were modulated by changing the content of Gd. It was demonstrated that the addition of Gd was favourable to the microwave absorption of FeSiAl composites. The minimum reflection loss (RL) of FeSiAl-3Gd composites can be up to −54.6 dB at 5.87 GHz when thickness is 3.5 mm. Radar cross section (RCS) simulation of FeSiAl-3Gd sample using CST with RCS reduction value of 24.38 dBm2. Its excellent microwave absorbing performance can be attributed to two factors. Firstly, the synergistic effect of FeSiAl and Gd improves the microwave absorption of the composites. Finally, Gd doping alters the surface morphology of the composites and provides multiple scattering paths, resulting in multiple losses of electromagnetic waves.

Oxygen vacancy diffusion and dynamics in Gd-doped CeO2: A GGA+U study

Using a generalized gradient approximation + Hubbard U method in the framework of density functional theory, we investigate the oxygen vacancy (VO) diffusion and dynamics in 3 × 3 × 3 CeO2 supercells with two Gd substitutions for Ce and an oxygen vacancy. Results show that (i) VO always migrates along the <100> direction, and (ii) VO would rather migrate across the Ce–Ce edges than across Ce–Gd or Gd–Gd edges. Especially, Gd only positively influences the migrations of oxygen vacancies within the third nearest neighbor, indicating that the increased Gd doping is required for extending the positive influence to the long-distance diffusion of oxygen vacancy, which offers an accountable explanation for the enhanced ion conduction experimentally observed in CeO2 with high Gd doping. The negative influence of heavy Gd doping on the VO diffusion is also discussed in detail. The outcome of the current work has implications in illuminating the role of dopants toward expediting the oxygen vacancy diffusion and in promoting the performance in CeO2-based materials and devices for environmentally friendly applications.

Influence of Gd content on structural, electronic, thermoelectric, and optical properties of WO3

WO3-based semiconductor materials are optimistic competitors for modern electronic devices because of their outstanding electronic and optical properties. Simulations on pure and Gd-doped WO3 compositions were executed using Tran and Blaha modified Becke–Johnson approximation. Experimentally, thin films of these compositions were prepared using the chemically derived technique. X-ray diffraction spectra of thin films exhibited cubic structure having space group 221-Pm-3m in all compositions. Field emission scanning electron micrographs reveal the uniform growth of thin films with rod-like compact morphology. The density of states spectra for electronic properties demonstrate the main contribution of W-d and O-p for pure WO3 with p-d hybridization while Gd containing composition provides an additional prominent contribution from f-orbital. Band structure shows an indirect transition for WO3 and band gap values were observed as 1.73 eV which decreased with increment of Gd content. A significant change in thermoelectric parameters was observed with an increment of temperature and Gd doping. The maximum value of the refractive index was observed as 3.02 in the visible energy regime and tends to decrease in Gd containing compositions. The experimentally obtained maximum dielectric constant was observed as 7.89 for pure WO3 and decreased to 4.58 for maximum Gd containing composition. Optical parameters like extinction, absorption coefficient, and optical conductivity show a sharp increment in visible energy region which make these compositions favorable for photovoltaic and optoelectronic applications. The experimentally obtained optical parameters are found in good agreement with simulated results obtained through TB-mBJ approximation.

Synergistic effect between the iron (III) oxyhydroxide and Gd-Fe2O3 photoanode interface resulted in an ultra-low onset potential for photoelectrochemical water oxidation

The onset potential is an important descriptor of the photoelectrochemical water oxidation performance of photoanodes. Herein, we prepared Gd-doped hematite (Gd-Fe2O3)/iron (III) oxyhydroxide (FeOOH) core-shell photoanodes by in-situ isovalent doping and secondary hydrothermal treatment. This Gd-Fe2O3/FeOOH photoanode shows a record alkaline water oxidation onset potential (0.59 V vs. reversible hydrogen electrode) in hematite-based photoanodes and a 2.4-fold increase in photocurrent density over pristine hematite. Detailed studies demonstrate that the origin of the ultra-low onset potential is mainly attributed to the synergistic effect of isovalent Gd-doping and FeOOH cocatalyst. Specifically, Gd doping enhances donor density and reduces charge transport resistance, and FeOOH cocatalyst significantly improves water oxidation kinetics. In addition, the strong interfacial coupling of FeOOH and Gd-Fe2O3 promotes electron flow, which also improves the charge separation remarkably. This work gives hope for the achievement of stable and bias-free hematite-based photoanodes.

Unique Semi‐Coherent Nanostructure Advancing Thermoelectrics of N‐Type PbSe

AbstractIntroducing nanostructures into bulk thermoelectric materials is an effective strategy for reducing lattice thermal conductivity (κlat). However, large numbers of hanging bonds emerge on account of lattice mismatch usually at the interfaces between nanostructures and matrix, thereby significantly deteriorating carrier mobility (µH) and seriously limiting thermoelectric performance. Here, utilizing the cointroduction of Gd‐Cu2Te into n‐type PbSe as a paradigm, the zT could be greatly improved. The conduction band flattening caused by Gd doping can successfully compensate for the small Seebeck coefficient in n‐type PbSe, thus achieving extraordinary electrical performance. Further advanced electron microscopy and X‐ray absorption fine structure spectra directly demonstrate that most of the Cu forms nanoscale Cu2Se precipitates, especially a unique semi‐coherent interface between the PbSe matrix and the Cu2Se nanoprecipitate is observed for the first time. Such nanoprecipitate accompanied by the semi‐coherent interface not only ensures higher µH as an excellent charge transfer mediator but also collectively scatters the heat‐carrying phonons over a wide frequency range to obtain the ultralow κlat, resulting in the prominent improvement of the ratio µH/κlat. The present finding represents an important step forward in electron–phonon decoupling via constructing semi‐coherent nanostructure and interface engineering, which should be applicable for other thermoelectric materials.