Rare Earth Doped Oxide Research Articles

Solar light driven enhanced in photocatalytic activity of novel Gd incorporated ZnO/SnO2 heterogeneous nanocomposites

The Gd-doped ZnO/SnO2 nanocomposites with various atomic percentages (0, 0.5, 0.8, and 1.2 at%) of gadolinium (coded as GdZS0, GdZS1, GdZS2, and GdZS3) was synthesis via the sol–gel method and explored for photodegradation against dye solutions exposing solar light irradiation. The synthesized nanocomposites were characterized employing the XRD, FTIR, FE-SEM, Raman spectroscopy, BET analysis and UV–Vis spectrophotometer. The FE-SEM results indicated that the formation of nanoparticles to nanoflowers covered with Gd ions was observed with an increased doping concentration of Gd. The optical bandgap was evaluated and found in the range of 3.21–3.27 eV for GdZS nanocomposites. The GdZS nano-photocatalysts were investigated against the degradation of different organic dyes and GdZS3 shows the highest degradation efficiencies of 99.3%, 98.3% and 99.4% towards MO, MB and RhB dyes, respectively at neutral pH in aqueous media. Before and after photodegradation. Biological oxygen demand and chemical oxygen demand tests to make estimations of mineralization. The investigations are very promising for the degradation process in rare earth doped metal oxide nanocomposites. A plausible photodegradation mechanism of synthesized nanocomposites under investigation has also been proposed.

Effect of rare earth oxide doping on microstructure and piezoelectric properties of BCTSZ ceramics

Effect of rare earth oxide doping on microstructure and piezoelectric properties of BCTSZ ceramics

Static and dynamic strain-driven photoluminescence tuning in rare-earth doped perovskite oxide thin films

Recently, there have been significant interest in the wide potential of photoluminescence (PL) response of rare-earth doped perovskite oxide thin films in the field of optoelectronics. This work reports an effective method to modulate the PL properties of 0.8 mol%Sm3+-doped BaTiO3 (BTO:Sm) thin films through static and dynamic strain. BTO:Sm films were epitaxially grown on LaAlO3 (LAO), 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT), MgO, and Mica single-crystal substrates by pulsed laser deposition technique. Compared with the BTO:Sm/PMN-PT heterostructure which experiences minimal lattice mismatch effect, the PL intensity of BTO:Sm/LAO and BTO:Sm/MgO is enhanced by 818.1% and 1014.7%, respectively, due to static tensile/compressive strain (-0.429% and 0.461%) during the epitaxial growth process. In the flexible BTO:Sm/Mica heterostructure, dynamic strain is introduced through mechanical bending. Compared with the unbent state, the u-type and n-type bending modes increase the relative changes in PL intensity (ΔI/I) by 599.0% and 768.5%, respectively. Particularly, BTO:Sm/Mica also exhibits a remarkable optical transmittance exceeding 75% (500–2500 nm). The enhancement of PL intensity is closely related to the adjustment of lattice strain, which changes the crystal field strength of the BTO:Sm and the radiative transition probability. This work provides valuable insights for designing future optoelectronic devices and environmental monitoring equipment. It has the potential to advance photonics and sensor technologies, paving the way for innovation and exploration in these fields.

Humidity-resistant hydrogen sensors based on rare-earth-doped tin dioxide nanofibers with hydrophobic mesoporous silica sieve encapsulation

Air humidity is a major factor that degrades the performance and long-term stability of metal-oxide-semiconductor (MOS) based gas sensors. In this work, we propose an encapsulation strategy by coating a mesoporous silica molecular sieve (SBA-15) on rare earth doped tin oxide (RE-SnO2) nanofibers for humidity-resistant hydrogen detection. In this design, the hydrophobic SBA-15 sieve layer effectively blocks the water molecules without affecting hydrogen diffusion, while the RE dopant greatly improves the responsivity and lowers down the operating temperature of the sensors, As a result, the Er-SnO2/SBA-15 and Tb-SnO2/SBA-15 sensors respectively show the maximum response values of 27.71 and 33.68 (to 10 ppm hydrogen at 280 °C, 4.67 and 5.67 times that of the bare SnO2 ones, respectively), short response/recovery time (< 1.0 s / < 1.0 s), as well as a low limit of detection for hydrogen (200 ppb) and a good gas selectivity. Under the protection of the SBA-15 sieve layer, the response retention of the sensors is significantly improved when the humidity increases from 25% to 85% RH (Er-doping, from 38.8% to 60.0%; Tb-doping, form 25.6–57.8%). Besides, further analysis on enhancement mechanism of response indicates that the SBA-15 coating contribute about 1/3 of the response enhancements via its own hydrogen physical adsorption capacity and the induced oxygen vacancies during the calcination processes.

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.

Optimization of safe doping level for enhanced CO2 flux in composite membrane

Rare earth doped oxides have been intensively promoted for the last two decades to embrace the high-performance target of a ceramic–carbonate composite CO2-separation membrane, with countless incidents of exsolution.

Influence of Eu2O3 on microstructure and electrical properties of ZnO-Pr6O11 based varistors

ZnO-Pr6O11-based ZnO nonlinear ceramics are well studied for their stability. Improving the electrical properties and stability of varistors has been an important part of the research and development of ZnO ceramics. The doping of rare-earth oxides in previous studies did not result in better performance of ceramics. In this study, the doping of rare earth element europium oxide is carried out by the traditional solid phase sintering method using metal oxides ZnO-Pr6O11–CoO–La2O3 (ZPCL) as the substrate, and the microstructure and electrical properties of the samples are tested. It is found that the doping of Eu2O3 helps to increase the grain boundary barrier, effectively improves the nonlinear coefficient of varistors, which is a very important electrical parameter, and reduces the leakage current. The best performance of the varistors is obtained at 1.5 mol% Eu2O3 doping, with the nonlinear coefficient of 18.7, the leakage current of 0.04 mA/cm2, the highest barrier height φb of 0.45 eV and the breakdown field of 1283 V/mm. This study provides a reasonable theoretical basis and experimental support for the improvement of the electrical properties of ZnO-Pr6O11-based ZnO ceramics, and lays a certain foundation for the doping of rare earth oxides in ceramics in the future.

X9R-type SrTiO3 based ceramics with colossal dielectric permittivity and low loss derived from defect engineering and high-energy ball milling

The miniaturization of electronic components has become a megatrend in the future, making colossal dielectric permittivity materials receive unprecedented attention. In this work, we proposed a universal route to achieve colossal dielectric permittivity, low loss factor and excellent dielectric temperature stability in rare earth doped perovskite oxide SrTiO3. Sm doped SrTiO3 ceramics prepared by high-energy ball milling exhibit ultrahigh dielectric permittivity 441,543, low loss factor 0.02, good dielectric temperature stability (<15 %) in the temperature range of −55–200 °C, and very high resistance 109Ω, which meets the EIA X9R standard, XPS and impedance spectra indicate that the electron-pinned defect-dipoles effect is the origin of colossal dielectric permittivity and low loss factor. This work shows that Sm-doped SrTiO3 activated by high-energy ball milling has broad prospects in the applications of thermally-stable miniaturized capacitors.

A porous Eu-PTA/Tb-SSA/ZrO2/ZnZrO3 light color adjustable phosphor: Luminescent property and application of warm white LED

Light emitting diode (LED) is the fourth generation lighting source, but it has some shortcomings such as complex chip packaging process and the unbalanced light color of phosphor in long-time application. In this study, a kind of Eu-terephthalic acid/Tb-sulfosalicylate/ZrO2/ZnZrO3 (Eu-PTA/Tb-SSA/ZrO2/ZnZrO3) phosphor with warm white light emission properties was prepared, and the warm white light LED (w-WLEDs) was successfully prepared by encapsulating Eu-PTA/Tb-SSA/ZrO2/ZnZrO3 phosphors together with 270 nm UV-chip. The ZrO2/ZnZrO3, Tb-SSA/ZrO2/ZnZrO3 and Eu-PTA/ZrO2/ZnZrO3 samples show blue emission, green emission and red emission under deep ultraviolet (UV, 270 nm) excitation, respectively. The Tb-SSA and Eu-PTA are co-doped into ZrO2/ZnZrO3 matrix with blue emission to achieve the warm white light emission, and the light color can be adjusted by controlling the doping amount of Eu3+ and Tb3+. Through the excitation method of single-component phosphor by the single chip, the complex chip packaging process of w-LED can be solved. By doping rare earth organic complexes into porous ZrO2/ZnZrO3 matrix, the problems of the light color unbalanced of phosphor and the low luminescence intensity of rare earth doped metal oxides composites can be solved.

Optical line broadening mechanisms in rare-earth doped oxide nanocrystals

Rare-earth ions in nanocrystals are promising solid-state platforms for quantum light-matter interfaces, combining millisecond-long nuclear spin T2 with kHz-range optical homogeneous linewidths. Coupled to optical micro-cavities these materials can enable scalable quantum processors, nanoscale quantum memories and single photon sources. Here, we report on optical dephasing in Eu3+:Y2O3 nanocrystals of 100 nm diameter through photon echo and spectral hole burning techniques as a function of temperature and magnetic field. We identify two-level systems (TLS) and electric noise as major line broadening mechanisms below 2 K and demonstrate that material-processing strategies such as high-power oxygen plasma can partially counteract these effects. Through modeling we show that these results are compatible with a reduction in the number of oxygen vacancy pairs in the nanocrystals by the oxygen plasma processing. These pairs, even at very low concentrations (hundreds of ppb), appear detrimental to optical coherence due to their ability to generate fluctuating electric fields.

Phase transformation kinetics and grain orientation of multi-cation doped (Yb, Sm) α/β-SiAlON ceramic tool materials

The densification behavior, phase transformation kinetics, and grain orientation of multi-cation doped (Yb, Sm) α/β-SiAlON ceramic tool materials prepared via spark plasma sintering (SPS) were studied. The results indicated that the (Yb, Sm) α/β-SiAlON ceramics were rapidly densified at 1540 °C. Various intergranular phases were formed due to the doping of rare earth oxides with different ionic radii. β-SiAlON precipitated ahead of α-SiAlON and elongated rapidly above 1600 °C. The β-SiAlON grains were preferred to orient in the direction perpendicular to the SPS pressure due to the dissolution/precipitation and grain rotation mechanism. The tendency of orientation decreased with the growth of β-SiAlON grains and the increase of liquid phase. The orientation of β-SiAlON grains resulted in anisotropic mechanical properties of (Yb, Sm) α/β-SiAlON ceramics, which fracture toughness measured in the perpendicular plane (⊥) was higher than that in the parallel plane (//).

A Review on Photocatalysis Used For Wastewater Treatment: Dye Degradation.

Water pollution is a global issue as a consequence of rapid industrialization and urbanization. Organic compounds which are generated from various industries produce problematic pollutants in water. Recently, metal oxide (TiO2, SnO2, CeO2, ZrO2, WO3, and ZnO)-based semiconductors have been explored as excellent photocatalysts in order to degrade organic pollutants in wastewater. However, their photocatalytic performance is limited due to their high band gap (UV range) and recombination time of photogenerated electron-hole pairs. Strategies for improving the performance of these metal oxides in the fields of photocatalysis are discussed. To improve their photocatalytic activity, researchers have investigated the concept of doping, formation ofnanocomposites and core-shell nanostructures of metal oxides. Rare-earth doped metal oxides have the advantage of interacting with functional groups quickly because of the 4f empty orbitals. More precisely, in this review, in-depth procedures for synthesizing rare earth doped metal oxides and nonocomposites, their efficiency towards organic pollutants degradation and sources have been discussed. The major goal of this review article is to propose high-performing, cost-effective combined tactics with prospective benefits for future industrial applications solutions.

Effect of doping rare earth oxides (RE= Sc, Y, Gd, Eu) on structural, thermal and mechanical properties of La2(Zr0.7Ce0.3)2O7 ceramics

Rare-earth (RE) oxide-doped La2(Zr0.7Ce0.3)2O7 (LZC) has attracted great interest in thermal barrier coatings (TBCs) because of its lower thermal conductivity. However, studies on the laws governing the effect of different types of RE oxide doping on the performance of LZC ceramics are limited. Therefore, in this study, different types of RE (Sc, Y, Gd and Eu) doped LZC ceramic bulks have been prepared using solid phase reaction method. The effects of RE doping on the crystal structure, mechanical properties and thermal properties of the LZC ceramics were investigated. The results indicated that all five ceramics exhibited a single pyrochlore phase structure, whereas their lattice constants were reduced after doping, with (La0.85Sc0.15)2(Zr0.7Ce0.3)2O7 having the lowest lattice constant. The effect of rare earth doping on the grain growth of LZC was not evident; however, it could significantly improve the hardness of LZC. In addition, doping with all four RE ions significantly reduced the thermal conductivity of the LZC ceramics, and the most significant reduction was observed for Gd3+ doping.

Dosimetric characterization for optimum concentration in rare earth doped hafnium oxide nanophosphors for medical radiotherapy applications

Rare earth (RE) doped HfO2 NPs was prepared using the co-precipitation method. This study focuses on the dosimetric characteristic of rare earth (Gd3+,Eu3+,Ho3+) activated HfO2 nanoparticles as potential thermoluminescence (TL) dosimeter for radiation therapy dosimetry. The selected dopant concentrations of 2.5 mol% of Gd, 7.5 mol% of Eu and 2.5 mol% of Ho were irradiated with a clinical gamma photon beam. From the study of dosimetric characterization, it is observed that there is an enhancement of dose response by incorporating rare earth materials. The results obtained in this work show that the Eu3+(7.5 mol%) satisfies the dosimetric characteristic (expect fading) other than an optimized dopant concentration of Gd and Ho. Eu3+ showed that the dosimetric features of reproducibility are high, the linear behavior for photon dose is a good and high degree of fading. The fading factors for the proposed dosimeters at room temperature, which explicit the high loss of TL signal is due to the un-stabilization of trapped charged effects. This detailed study can be useful for the further development of highly efficient ionizing radiation dosimetry.

Effect of rare earth oxide doping on microstructure and mechanical property of Mo-30 W solid solution alloy

Oxide dispersion-strengthened (ODS) molybdenum‑tungsten (MoW) alloys are ideal materials for plasma-facing components of fusion reactors. In this paper, the effects of rare earth oxides (RExOy) Y2O3, CeO2 and La2O3 on the sintering behavior, microstructural and mechanical properties of MoW solid solution alloys were investigated. The initial alloy powders were produced by spray drying combined with the two-step reduction method (composed of carbothermal reduction and deep hydrogen reduction steps), and the solid solution alloy with good mechanical properties was prepared by subsequent sintering. The results showed that the doping of rare earth oxides suppressed the grain growth of MoW alloy, and thus improved the mechanical properties. Compared with CeO2 and Y2O3, the doping of La2O3 is more favorable to obtain dense and fine-grained MoW solid-solution alloys. The doping of La2O3 produced a larger Zener force and interfacial drag force, which effectively hindered the grain boundary migration and refined the grains. The microhardness and bending strength of Mo-30 W-1La2O3 alloy reached the maximum values of 557 HV and 771 MPa.

Low-temperature sintered Pr3+/Er3+ codoped Bi2Mo2O9 microcrystals for multimode optical thermometry and anti-counterfeiting

Lanthanide-doped oxide materials generally require high sintering temperatures for optical applications such as temperature sensing and anti-counterfeiting. In this work, the highly crystalline 1%Pr3+/1%Er3+ co-doped Bi2Mo2O9 phosphor is reported with a low sintering temperature of 923 K. Pr3+ in the Bi2Mo2O9 host has a narrow emission band of 3P0–3H6 transition at 624 nm due to the suppressed broadening of electronic transitions in the homogeneous crystal field. Multimode temperature sensing is realized based on the upconversion and downshifting emissions as well as the luminescence lifetimes of the as-prepared phosphor. The temperature sensing based on the downshifting emission bands of this phosphor at 530 and 624 nm achieves the maximum absolute and relative sensitivities of 0.693 K−1 at 568 K and 1.88% K−1 at 483 K, respectively. For anti-counterfeiting applications, this phosphor can display bright yellow fluorescence at the liquid nitrogen cooling temperature, rather than white or pale colors. The white-color emission of this phosphor excited by 254 nm can also be used for lighting. The lanthanide-doped Bi2Mo2O9 can achieve favorable luminescence performance at much lower sintering temperature than most oxide phosphors, and is not only stable but also has the potential for in-situ sintering on materials that are not resistant to high temperature.

Structural and optical investigations in undoped and rare-earth doped zinc oxide nanoparticles for photon upconversion based applications

The present work reports comprehensive investigations of the physical properties of undoped and rare-earth (RE3+) doped ZnO based upconversion nanoparticles. X-ray diffraction analysis of these nanoparticles reveals the hexagonal wurtzite structure. The induced-strain value of the RE3+ doped ZnO nanoparticles increased by almost one order of magnitude, and their mean particle size reduced from 36 nm to 17 nm. The scanning electron microscopic images showed that the particles retained the spherical shape in the undoped and doped conditions. The elemental maps confirmed the uniform distribution of the RE3+ dopants. The recorded absorbance spectrum for the doped nanoparticles showed significant absorption in ultraviolet and near infra-red regions owing to the band-band transitions and the deep defect level transitions that are induced due to intrinsic and extrinsic defect states. A detailed analysis of the defect states of these samples is described based on the Urbach energy studies. An intense peak observed at 980 nm suggests the possibility of photon upconversion in the doped nanoparticles. A simplified energy diagram (as depicted below) has demonstrated the multi-photon absorption and possible upconversion mechanisms. The optical absorption spectrum of RE3+ doped ZnO nanocrystals encourages the promising application of these materials in diverse fields, particularly in biomedical and photovoltaic applications.

Boosting overall electrochemical water splitting via rare earth doped cupric oxide nanoparticles obtained by co-precipitation technique

The development of electrocatalyst based on nonprecious metals has been a persistent issue as electrochemical water splitting requires electrocatalyst with advanced activity and stability. Further, the electrocatalyst must require low overpotential above the standard potential (>1.23 V) of water splitting to produce hydrogen. This study presents the facile co-precipitation derived rare earth dysprosium (Dy) doped cupric oxide nanoparticles (Cu1−xDyxO) as a non-noble transition metal oxide nanoparticle. The 3 % Dy doped CuO (3 % Dy/CuO) and 1 % Dy doped CuO (1 % Dy/CuO) electrocatalysts showed excellent Oxygen Evolution Reaction (OER) at 1.55 V vs RHE and Hydrogen Evolution Reaction (HER) at − 0.036 V vs RHE in aqueous 1 M KOH aqueous electrolyte to attain the benchmark current density (10 mA cm−2). The stability of the driven electrocatalyst in a bi-functional electrocatalytic setup was monitored for 24 h and was found to be exhibiting a cell voltage of about 2.1 V at 30 mA cm−2 constant current density. Further, the retention capability of the electrode was observed to be 99 % with a very minimal loss. This study hugely suggests the promising consequence of doping rare earth onto a non-precious metal oxide-based electrocatalyst, making it a highly effective bifunctional material for water splitting.

Locally-ordered A-site vacancy assisted photoluminescence enhancement in simply rare-earth doped perovskite oxide

An Sm3+and A-site vacancy doped CaTiO3phosphors, which demonstrate larger PL intensity than phosphors without vacancies. The formation of VAordering enables the exchange of charge between [Ca/VAOn] and [CaO12] clusters for enhanced PL properties.

A Review on Development of Rare Earth Based Contrast Agents for Dual Modal Imaging of Cancer Cells

The risk of developing cancer is becoming higher due to the genetic and environmental factors. Diagnosing cancer at an early stage is a very big challenge to clinicians and researchers. Several imaging modalities are being used in hospitals for diagnostic purposes. But each imaging modality has some limitations to identify the cancer cells at their early stage. Magnetic resonance imaging can be combined with optical imaging for better diagnosis of cancer. This concept of combining two imaging modalities is termed as ‘dual modal imaging’. In dual modal imaging, the limitation of one technique becomes the advantage of other. This review article focuses on the dual modal imaging which is achieved by using rare earth doped gadolinium oxide nanoparticles. By doping the rare earth ions into the gadolinium oxide matrix, both the optical and magnetic properties of the material are shared.