Rare Earth Doping Research Articles

Effects of multi-scale precipitated phases on the toughness of FeCrAl alloy investigated by varying cooling mode and RE doping

In order to clarify the factors affecting the toughness of FeCrAl alloy, a systematic investigation on the correlation between microstructure and mechanical properties of hot-rolled 0Cr21Al6 sheet was performed through regulating cooling rate and rare earth (RE) element added in the alloy. It is worked out that a slower cooling rate results in the increase of brittleness for the alloy mainly due to nanoscale α' precipitates, while RE element promotes recrystallization and hinders the precipitation of sub-micron (Ti,Nb)P, which is beneficial to improving the toughness of alloy. These findings offer a valuable technical guidance for enhancing the toughness of FeCrAl alloy.

Exploring the Regulatory Mechanism of ZnS Materials under Stress and Re Doping: Insights from Density Functional Theory

The application prospects of ZnS stress luminescent materials cover many fields such as high‐precision structural monitoring, smart materials, biomedical imaging, and new sensor technologies, which bring broad application prospects and significance to them in the fields of engineering, medicine, and scientific research. In this article, the electronic structure and optical properties of ZnS materials are successfully regulated by applying pressure and doping rare earth metals (Re), and it is found that the regulation of the luminescence properties of ZnS is the result of stress and doping interactions. Specifically, when pressure is applied or Re metal doping, the lattice structure is deformed and the atomic spacing is adjusted, which affects the electronic energy level distribution and optical properties of ZnS materials. Computational analysis of density functional theory (DFT) reveals the microscopic mechanisms behind these changes, including changes in lattice parameters, adjustment of bond length, and changes in band structure. This study provides theoretical guidance for the design and synthesis of high‐performance and high‐stability ZnS light‐emitting materials, and is of great significance for expanding the application of ZnS in the field of lasers and sensors.

Comparing thermoluminescence data on lanthanides in 36 compounds with predictions from vacuum referred binding energy diagrams

Thermoluminescence (TL) often involves the liberation of a charge carrier (an electron or a hole) from a charge carrier trapping centre into the conduction band (CB) or the valence band (VB) with subsequent recombination with a counter charge carrier at a luminescence centre. TL glow peak analysis can provide the energy ΔEt needed to liberate such charge carrier which then defines the location of the charge transition levels (CTL) of the carrier trapping centres below the CB-bottom or above the VB-top. The temperature at the maximum of the TL glow peak changes 3–4 K per 0.01 eV change in ΔEt thus providing an extremely sensitive probe of energy changes in CTLs. This work collects and reviews data on glow peaks due to electron or hole release from lanthanide dopants in 36 different inorganic compounds. To compare results from different literature sources, data were always re-analysed using the same method that is solely based on the temperature at the maximum of the glow peak. The changes in ΔEt along the lanthanides series provides insight at the sub 0.1 eV level on the changes in CTL energies. We will use a compound-dependent parameter to account for the nephelauxetic effect and a compound dependent parameter to account for lattice relaxation around the lanthanide. Together with information from lanthanide luminescence spectroscopy, the vacuum referred binding energy (VRBE) diagram will be constructed for each compound. The lanthanide electron or hole trap depth read from the VRBE scheme will be compared with that derived from the TL glow peak. Surprisingly good agreement will be demonstrated.

Exploration of structural, magnetic, and magnetocaloric characteristics of double perovskites HoRCoMnO6 (R=Ho, Gd, Eu or Nd)

A conventional solid-state process was used to synthesize the double perovskite materials HoRCoMnO6 (R=Ho, Gd, Eu, Nd). The structural properties of the compounds were investigated using X-ray powder diffraction (XRD). The results revealed that Ho₂CoMnO₆ crystallizes in a monoclinic structure with the P21/n space group. In contrast, the other compounds HoRCoMnO6 (R=Gd, Eu, or Nd) exhibit an orthorhombic structure with the Pnma space group. As a result, the average crystallite size also changes as a function of rare-earth element doping. This investigation reveals that the magnetic properties of the compounds studied are significantly dependent on the doping elements. The Curie temperature TC, for example, increases from 80 to 118 °C with the ionic radii of rare earths increasing. Furthermore, the study of the magnetocaloric effect (MCE) shows that the maximum of the entropy variation (−ΔSMmax) increases from 4.97 to 6.06 J/(kg∙K) under a magnetic field of 5 T with substitution by rare-earth ions. To examine the efficiency of MCE materials, the relative cooling power (RCP) was evaluated and is found to increase with increment of rare-earth radius till 406.69 J/kg for Nd. The mean entropy variation with temperature (TEC) was also studied. Due to their significant magnetocaloric performance, HoRCoMnO6 (noted as HRCMO) compounds (with R=Ho, Gd, Eu or Nd) could be good candidates for low-temperature magnetic cooling applications

An appraisal of the role of lanthanide doping in stabilization and performance improvement of [Sm3+-Eu3+-Tm3+]:CsPbI2.2Br0.8 for high-performance energy systems

Energy sustainability in the present era is associated with the adoption of the integrated and consolidated approach to generate, convert, and store energy. Current investigation is demonstrative of the first exploration of the novel CsPbI2.2Br0.8 transformed by lanthanide triple doping forming [Sm3+-Eu3+-Tm3+]:CsPbI2.2Br0.8 (SET:CPVSK). Also, SET:CPVSK is the for the first time employed in multitudinous energy applications. SET:CPVSK excelled over the pristine material with the minimal alterations in the band gap energy spanning around 1.65 – 1.72 eV tracked for 28 days. With the cubic phase, SET:CPVSK thin films exhibited excellent morphology with the tighter binding to substrate. As light harvesting layers inside entirely ambient perovskite solar cells, the efficiency of the cells increased to 16.31 % from 7.49 % upon doping with an improvement in other photovoltaic features also. Electro-catalytic response of the SET:CPVSK towards hydrogen generation was magnanimous with the lower overpotential and kinetic Tafel slope of 130 mV and 116.5 mV dec−1, signifying Volmer-Heyrovsky mechanistic route. With the service life of 100 min, the developed electro-catalyst expressed sustainable output. In terms of the charge storage, the unit capacity was improved to 622.4 mAH g−1 upon doping while the other electrode can only reach up to 394.2 mAH g−1. Furthermore, the resistive response of this electrode was also appreciable with the lower equivalent series resistance (Rs) i.e. 0.41 Ω, showing auspiciousness for practical applications.

Rare Earth Dopants Enhance Thermocatalytic Activity of Manganese Oxides on Corrugated Silica Carriers for Formaldehyde Degradation

AbstractThe development of high efficiency thermocatalysts remains a great challenge for gaseous formaldehyde elimination. Herein, rare earth‐doped manganese dioxide (RE‐MnO2) particles with sizes of approximately 200 nm were deposited on corrugated silica carrier (CSC) by using cerium or samarium as dopants. One part of rare earth ions in RE‐MnO2/CSC were substituted for the manganese ions in α‐MnO2, and the other part existed in the form of cerium oxide or samarium oxide. RE‐MnO2/CSC exhibited better thermocatalytic activity than MnO2/CSC. The formaldehyde removal efficiency over RE‐MnO2/CSC reached nearly 100 % even after cycle tests of 5 times. Both the cerium and samarium doping accelerated HCHO oxidation via increasing lattice oxygen and Mn4+ amounts, improving low‐temperature redox properties, and reducing apparent activation energy. Notably, the RE oxides in the catalysts played different roles in HCHO degradation. Samarium oxide did not possess thermocatalytic activity, while cerium oxide in RE‐MnO2/CSC participated directly in the formaldehyde degradation via the CeO2↔Ce2O3 redox reaction and facilitated the oxidation of Mn2O3 into MnO2. This work revealed the effect mechanisms of RE doping and RE oxide on the enhanced thermocatalytic activity, and provided a novel viewpoint to develop RE‐doped catalysts for formaldehyde removal.

NIR-II fluorescence lateral flow immunosensor based on efficient energy transfer probe for point-of-care testing of tumor biomarkers

Fluorescence lateral flow immunoassay (LFA) has emerged as a powerful tool for rapid screening of various biomarkers owing to its simplicity, sensitivity and flexibility. It is noteworthy that fluorescent probe mainly determines the analytical performance of LFA. Due to the emission and excitation wavelengths are located in the visible region, most fluorophores are inevitably subject to light scattering and background autofluorescence. Herein, we reported a novel LFA sensor based on the second near-infrared (NIR-II) fluorescent probe with excellent anti-interference capability. The designed NIR-II probe was the Nd3+ and Yb3+ doped rare earth nanoparticles (RENPs) by employing Nd3+ as energy donor and Yb3+ as energy acceptor, which of the donor-acceptor energy transfer (ET) efficiency reached up to 80.7 %. Meanwhile, relying on the convenient and effective encapsulation strategy of poly(lactic-co-glycolic acid) (PLGA) microspheres to RENPs, the surface functionalized NIR-II probe (RE@PLGA) was obtained for subsequent bioconjugation. Benefiting from the optical advantages of NIR-II probe, this proposed NIR-II LFA displayed a good linear relationship ranging from 7 ng/mL to 200 ng/mL for the detection of α-fetoprotein (AFP), an important biomarker of hepatocellular carcinoma (HCC). The limit of detection (LOD) was determined as low as 3.0 ng/mL, which was of 8.3 times lower than clinical cutoff value. It is promising that LFA sensor based on this efficient RENPs probe provides new opportunities for high sensitive detection of various biomarkers in biological samples.

Effect of Rare-Earth Compounds on the Photocatalytic Performance of ZnIn2S4: A Review

Semiconductor photocatalysis is considered one of the efficient and clean environmental technologies in the treatment of organic dye wastewater. Indium zinc sulfide (ZnIn2S4) is favored among many photocatalysts because of its narrow-forbidden bandwidth, good visible light absorption properties, suitable conduction and valence band positions, high chemical stability, low cost, easy preparation and low toxicity. However, indium zinc sulfide (ZnIn2S4) still faces the disadvantages of low visible light utilization and high photogenerated carrier complexation rate. In this paper, we introduce rare-earth ion doping and heterojunction of rare-earth oxides with ZnIn2S4 to improve photocatalytic efficiency, and we also review the current research status and development prospects of indium zinc sulfide in recent years.

Enhancing light output of WSLED with microlens array fabricated on Tb³⁺/Sm³⁺ co-doped fluorophosphate glass via hot embossing

In this study, Tb3+/Sm3+ co-doped NaPO3–BaF2–AlF3–CaF2 glasses were synthesized using the melt quenching method. These glasses exhibit a glass transition temperature below 380 °C and maintain optical transparency close to 90% within the visible spectrum. Furthermore, under UV excitation, the emission shows a wide spectrum and varies with the rare-earth doping ratio or excitation wavelength. Hence, this glass was introduced into the wide-spectrum light-emitting diode (WSLED) application. Moreover, a microlens array was fabricated on the glass surface using the hot embossing technique. In fact, the microlens array enhanced the light output power of the WSLED by 5% at a driving current of 150 mA.

Multicolor Long-Term Single-Particle Tracking Using 10 nm Upconverting Nanoparticles.

Single-particle tracking (SPT) is a powerful technique to unveil molecular behaviors crucial to the understanding of many biological processes, but it is limited by factors such as probe photostability and spectral orthogonality. To overcome these limitations, we develop upconverting nanoparticles (UCNPs), which are photostable over several hours at the single-particle level, enabling long-term multicolor SPT. We investigate the brightness of core-shell UCNPs as a function of inert shell thickness to minimize particle size while maintaining sufficient signal for SPT. We explore different rare-earth dopants to optimize for the brightest probes and find that UCNPs doped with 2% Tm3+/30% Yb3+, 10% Er3+/90% Yb3+, and 15% Tm3+/85% Yb3+ represent the optimal probes for blue, green, and near-infrared emission, respectively. The multiplexed 10 nm probes enable three-color single-particle tracking on live HeLa cells for tens of minutes using a single, near-infrared excitation source. These photostable and multiplexed probes open new avenues for numerous biological applications.

The Impact of the Amorphous-to-Crystalline Transition on the Upconversion Luminescence in Er3+-Doped Ga2O3 Thin Films

Gallium oxide (Ga2O3) is an emerging wide bandgap semiconductor promising a wide range of important applications. However, mass production of high-quality crystalline Ga2O3 still suffers from limitations associated with poor reproducibility and low efficiency. Low-temperature-grown amorphous Ga2O3 demonstrates comparable performance with its crystalline counterparts. Lanthanide Er3+-doped Ga2O3 (Ga2O3: Er) possesses great potential for developing light-emitting devices, photodetectors, solid-state lasers, and optical waveguides. The host circumstance can exert a crystal field around the lanthanide dopants and strongly influence their photoluminescence properties. Here, we present a systematical study of the impact of amorphous-to-crystalline transition on the upconversion photoluminescence in Ga2O3: Er thin films. Through controlling the growth temperature of Ga2O3: Er films, the upconversion luminescence of crystalline Ga2O3: Er thin film is strongly enhanced over 100 times that of the amorphous Ga2O3: Er thin film. Moreover, the variation of photoluminescence reflects the amorphous-to-crystalline transformation of the Ga2O3: Er thin films. These results will aid further designs of favorable optoelectronic devices integrated with lanthanide-doped Ga2O3 thin films.

Improvement of SnFe2O4 OER electrochemical property by Sm doping for water splitting

Electrocatalysts are crucial for achieving highly efficient renewable energy conversion and storage applications. Nevertheless, doping proves to be a successful approach in creating affordable spinel oxides that exhibit exceptional electrochemical capabilities. Our study focuses on the preparation of a samarium (Sm)-doped SnFe2O4 catalyst to expand the activity and stability of the oxygen evolution reaction (OER). However, the Sm-doped SnFe2O4 catalyst shows a highly encouraging overpotential of 179 mV at a current density of 10 mA cm−2 and a reduced Tafel slope of 32 mA dec−1. It maintains its durability for a duration of 40 h and even after undergoing 5000th cycles. The Sm-doped SnFe2O4 catalyst exhibits several positive effects, including reduced overpotential, higher catalytic current density, improved charge transfer kinetics (Rct = 0.29 Ω), and increased ECSA (111.62 cm2) value. These improved superior activity of Sm-doped SnFe2O4 catalyst can be attributed to factors such as its unique interconnected structures morphology, strong synergistic effects of Sm with Sn and Fe and the robust OH− adsorption, which are more pronounced compared to the un-doped SnFe2O4, which greatly enhanced their performance in OER activity. These findings indicate that by incorporating rare earth (Sm) dopant with a high valence state, spinel oxide can be fine-tuned to potentially enhance OER optimization for energy-producing applications.

Voltage‐Driven Molecular Orientation with Optical Synergy in Rare Earth Doped Polymer Dispersed Liquid Crystals

AbstractAchieving reversible large‐span photoluminescence regulation still faces difficulties due to limitations in the design or preparation conditions of related materials. Herein, a universal strategy that combines voltage‐driven molecular orientation with optical synergy between rare earth (RE) doped materials and polymer dispersed liquid crystals (PDLC) is proposed to achieve large‐span reversible opto‐electrically synergistic induced multi‐response photoluminescence regulation. The obtained Eu(tta)3phen/PDLC composites can exhibit different emission colors reversible transform from purple to purplish‐pink depending on the excitation wavelength and the applied electric voltage. The interaction between PDLC and Eu(tta)3phen is analyzed and the field distribution of internal microstructures is simulated using the finite‐difference time‐domain method, providing a theoretical basis for the voltage‐dependent photon interactions. The potential applications of Eu(tta)3phen/PDLC composites for anticounterfeiting is suggested by demonstrating a proof‐of‐concept anticounterfeiting system based on the composites. The strategy of opto‐electrically synergistic induced multi‐response photoluminescence regulation, with general applicability, can be easily extended to other RE doped materials and PDLC systems, opening up new possibilities for photoluminescence regulation research.

Upconversion Nano‐Composites for Orthogonal Trichromatic Luminescence Aiming at High Color Purity Volume Display

AbstractOrthogonal three‐color luminescence materials designed based on lanthanide doping multi‐component nano‐systems have exhibited great potential in volume display technology. Previous studies devoted to integrate the different color emitters within a single core‐shell nanoparticle, which suffers complexity in synthesis and difficulty in repeatability. In this work, an alternative is proposed. Three kinds of upconversion nanocrystals (UCNCs) with relatively simple configurations are prepared separately. Each kind of nanocrystals takes charge of emit a specific color upon one particular excitation (i.e., 808, 980, and 1540 nm pumps). Luminescent property of the mixture containing these nanocrystals are investigated. Excitation wavelength driven orthogonal three‐color luminescence property is found in this mixture. With the combination excitation, the emission color can be modulated, covering a gamut with its aera of 110% sRGB, superior to the previous reports. In addition, a quantized strategy to evaluate the orthogonality of the luminescence is also proposed, which will be useful for the further investigation and development of remote‐type controlled luminescent materials. Finally, the demonstration of colored 3D display application is conducted and presented in this work.

Phase stability and electronic structure of CsPbBr3 perovskites under rare-earth doping and hydrostatic pressure

Phase stability and electronic structure of CsPbBr3 perovskites under rare-earth doping and hydrostatic pressure

Effects of rare earth dopants on the EO properties and domain configurations in PMN-PT transparent ceramics

Effects of rare earth dopants on the EO properties and domain configurations in PMN-PT transparent ceramics

Unveiling the role of rare earth dopant in metal molybdate nanocomposites via facile microwave-combustion strategy and their effect on antibacterial activity

Abstract Developing a robust material holding antimicrobial assets has been an efficient strategy for reducing the risk of infections related to healthcare, significantly with medical devices and touch surfaces. Molybdenum-based compounds have drawn momentous attraction because of their unique characteristics. A series of undoped and 5 % rare earth (Ce & La) doped metal (Ni, Co & Bi) molybdate nanocomposites have been prepared by facile microwave combustion method and characterized. The present study investigates the effect of dopants on crystal structure and morphology, and their impact on anti-bacterial properties is noticed. The UV–Vis. absorption spectra of all samples show a broad absorption band between 280 and 430 nm. The antibacterial properties of the prepared nanocomposites have been examined by the agar diffusion method against three Gram-positive and two Gram-negative bacteria, showing good bactericidal efficiency for all samples, except 5 % Ce–NiMoO4 (antibacterial activity exclusively against Gram-positive bacteria) and 5 % La–NiMoO4 (no antibacterial activity) nanocomposites. This work provided a novel pathway in the biomaterial field.

Impact of Nd3+, Er3+ions on the structural, morphological and opto-electrical properties of ZrO2/La2O3doped Y2O3 ceramics

In the present work, the authors have studied double doping of Rare Earth Elements (Nd3+, Er3+) into the lattice of Y2O3 ceramic in the presence of sintering additives ZrO2+La2O3 having formula (Y0.915-xZr0.02La0.06Nd0.005Erx)2O3 where x= (0.5, 1.0, 1.5 at. %). The samples are synthesized using co-precipitation method. X-ray diffraction results reveals the formation of Y2O3 structure having cubic unit cell and matched with JCPDS card No. 41-1105. A gradual shift towards higher angle side at 2θ = 29.2° has been observed with variation in Er doping. The particle size varied from 123 nm to 52 nm with doping and has a homogenous distribution. The presence of different dopants have been confirmed by XPS. The powder mixture was sintered at 1700 °C for 10hrs in an inert atmosphere, though resulting in translucent pellets when measured in the range of 200–2200 nm, due to non-uniform heating and different grain size. Under the excitation of 350 nm, the samples emitted blue, green, violet and indigo colours wavelengths, confirming transition from 4F11/2 orbitals and their band gap also decreases from 5.2 eV to 4.80 eV. The sintered samples presented a dielectric constant of 15, which goes up to 18 upon increasing the concentration of Er. These results demonstrated the correlation and the effect of double doping on Y2O3 for its opto-electronic applications.

Achieving giant field-induced strain in BS-modified BNKT lead-free ferroelectric ceramics

Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3 (BNT-BKT) binary systems with the morphotropic phase boundary (MPB) are promising candidates for piezoelectric actuators. However, pure BNT-BKT ceramics commonly exhibit unfavorable electric field-induced strain, which is insufficient to meet the requirements for actuator applications. Rare earth-containing dopants have been extensively explored to modify various materials due to their unique optical, magnetic, and electronic properties. Here, by introducing rare earth ion-containing dopants BiScO3 (BS), the electrical properties of Bi0.5(Na0.84K0.16)0.5TiO3 (BNKT) lead-free ferroelectric ceramics have been modified. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results suggest that the introduction of BS results in an increase in tetragonal (T) phases, reduced grain sizes, and uniform morphologies. Ferroelectric measurements demonstrate that the BS-containing ceramics show slimmer hysteresis loops. The BNKT-2BS ceramics show a noteworthy improvement in electric field-induced strain, with bipolar and monopolar strains of 0.58% and 0.68%, respectively, which are almost 4 times and 6 times higher than those of pure BNKT ceramics. Furthermore, the corresponding normalized strain (d33*) also achieves high values of 967 pm/V and 1133 pm/V, respectively. Temperature-dependent dielectric measurements reveal that BS-containing ceramics exhibit good relaxor characteristics with frequency dispersion and diffuse phase transitions. This study presents a sufficient and feasible strategy for the optimization of strain performance in large displacement actuator applications.

Simultaneously significant transparency enhancement and efficient temperature feedback achieved in AlON ceramic through luminescent rare earth doping

Activator-doped aluminum oxynitride (γ-AlON) could provide an extremely versatile transparent ceramic with photothermal feedback, opening the door to many new applications and devices for use in extreme conditions. However, existing AlON transparent ceramics have failed to achieve temperature-responsive luminescence. To address this, a simple-to-implement luminescent rare-earth doping strategy for fabricating AlON transparent ceramic with efficient temperature feedback is proposed and demonstrated. Luminescent Pr2O3 serves as the illustrative example. Benefiting from the liquid phase formed by Pr2O3 and the thermal coupling between the 3P1 and 3P0 levels of Pr3+, AlON ceramics doped with Pr2O3 exhibit significantly elevated transparency and temperature-responsive luminescence. More importantly, the AlON:Pr ceramic can serve as photothermal feedback windows, which presents attractive performance. This paradigm fills an important gap in the AlON transparent ceramics for temperature feedback windows, and will inspire the controllable design of luminescent rare-earth doped AlON ceramics for use in harsh conditions.