Incorporation Of Rare-earth Ions Research Articles

Mössbauer study of iron oxide nanoparticles

AbstractMagnetic nanoparticles have recently attracted attention for biochemical and medical applications like drug delivery and hyperthermia for a variety of reasons with most important being their stability, chemical compatibility, and suitable magnetic properties like moderate specific mass magnetization. Cobalt ferrites are a well‐studied family of materials and the partial substitution of Fe3+ cations by rare earth (RE) ones may be used to tune the magnetic properties. In the present work pure and substituted Co ferrite nanoparticles with nominal stoichiometry CoFe2‐xRxO4 (R = Yb, Gd; x = 0.05, 0.1, 0.3) synthesized by the co‐precipitation method are studied with 57Fe Mössbauer spectroscopy in order to determine the incorporation of RE ions in the spinel lattice. The fitting procedure was based on the standard spinel model using two sextets for the octahedral and the tetrahedral coordinated positions of Fe atoms. All isomer shift values were found within the typical range of high spin ferric ions while quadrupole splitting values strongly suggest that there is a substitution preference; RE ions replace iron ones in octahedral sites. The inversion parameter was found to decrease with RE content (lowest value about 0.534 for CoFe1.90Yb0.10O4) and thermal treatment always results in changing the material towards normal spinel, while pure CoFe2O4 was inverse. Thermal treatment of substituted materials in ambient air at temperature range 1500‐1700 K for 12 hours increase crystallite size and changes the degree of inversion.This article is protected by copyright. All rights reserved.

Photocatalytic activity of barium titanate composites with zinc oxide doped with lanthanide ions for sulfamethoxazole degradation

This comprehensive study delves into the structural and optical characteristics of barium titanate (BT) and zinc oxide (ZnO) heterostructures doped with europium (Eu), erbium (Er), and ytterbium (Yb), alongside their application in the photodegradation of sulfamethoxazole antibiotic (SMX). The heterostructures, prepared via a hydrothermal process, exhibit a heterogeneous connection between doped ZnO nanoparticles and the BT dielectric material with crystalline nature and chemical composition. Moreover, a significant reduction in the bandgap of the doped BT@ZnO:Ln heterostructures compared to undoped counterparts, indicating successful dopant incorporation and the creation of new sub-bands within the bandgap. A minimal adsorption interaction between SMX and the nanomaterials was observed. While BT alone exhibited limited photocatalytic activity, doping with ZnO significantly enhanced performance. Notably, the BT@ZnO:Yb heterostructure exhibited exceptional SMX degradation (99%) within 60 minutes. Incorporation of rare-earth ions (Eu, Er, Yb) not only improved photocatalytic activity but also acted as electron scavengers, mitigating electron-hole recombination. Furthermore, the investigation into the reuse of BT@ZnO:Yb 5%mol showed sustained high efficiency over three cycles. Mechanistic insights into SMX degradation pathways highlight the predominant role of hydroxyl radicals and electron-hole processes. Overall, these findings contribute significantly to the advancement of photocatalytic materials based on composites doped with lanthanide ions for applications in environmental wastewater treatment.

Electrical Resistivity Behavior and Small Polaron Conduction Transport Mechanism in Semiconducting <I>R</I>MnO<sub>3</sub> Manganites

Rare earth manganites, denoted by the chemical formula <I>R</I>MnO<sub>3</sub>, where <I>R</I> signifies a rare earth element, have garnered significant interest in recent years. These perovskite oxides exhibit intriguing phenomena such as multiferroicity, ferroelectricity, and colossal magnetoresistance, primarily attributed to the role of polarons in conduction. The incorporation of rare earth ions imparts flexibility, making these compounds promising for applications in spintronics, sensors, and information storage devices. This study delves into the electrical resistivity behavior and Small Polaron Conduction (SPC) mechanisms of rare earth manganites, particularly <I>R</I>MnO<sub>3</sub>. In this manuscript, electrical resistivity of the pristine <I>R</I>MnO<sub>3</sub> (<I>R</I> = Sm, Eu, Gd) manganites are analyzed within the framework of adiabatic nearest-neighbor hopping of SPC. The high temperature state of <I>R</I>MnO<sub>3</sub> within the SPC mechanism is influenced by polaron concentration, hopping distance, and resistivity coefficient. The localized charge carriers in undoped manganites enable one to estimate the activation energy for the electrical conduction. The activation energy decreases with the decrease in ionic radii from Sm to Gd. Deduced polaron activation energy is low for GdMnO<sub>3</sub> as compared to SmMnO<sub>3</sub> and is attributed to reducing disorder state in GdMnO<sub>3</sub> as compared to SmMnO<sub>3</sub>. This work contributes to the fundamental understanding of condensed matter physics and the potential applications of rare earth manganites in emerging technologies. The interplay between electrical resistivity and Small Polaron Conduction offers insights for customizing these materials for specific technological needs.

Tunable Visible Light and Energy Transfer Mechanism in Tm3+ and Silver Nanoclusters within Co-Doped GeO2-PbO Glasses.

This study introduces a novel method for producing Ag nanoclusters (NCs) within GeO2-PbO glasses doped with Tm3+ ions. Sample preparation involved the melt-quenching method, employing adequate heat treatment to facilitate Ag NC formation. Absorption spectroscopy confirmed trivalent rare-earth ion incorporation. Ag NC identification and the amorphous structure were observed using transmission electron microscopy. A tunable visible emission from blue to the yellow region was observed. The energy transfer mechanism from Ag NCs to Tm3+ ions was demonstrated by enhanced 800 nm emission under 380 and 400 nm excitations, mainly for samples with a higher concentration of Ag NCs; moreover, the long lifetime decrease of Ag NCs at 600 nm (excited at 380 and 400 nm) and the lifetime increase of Tm3+ ions at 800 nm (excitation of 405 nm) corroborated the energy transfer between those species. Therefore, we attribute this energy transfer mechanism to the decay processes from S1→T1 and T1→S0 levels of Ag NCs to the 3H4 level of Tm3+ ions serving as the primary path of energy transfer in this system. GeO2-PbO glasses demonstrated potential as materials to host Ag NCs with applications for photonics as solar cell coatings, wideband light sources, and continuous-wave tunable lasers in the visible spectrum, among others.

Highly strong and tough silk by feeding silkworms with rare earth ion-modified diets

Nature-derived silk fibers possess excellent biocompatibility, sustainability, and mechanical properties, yet producing strong and tough silk fibers in a facile and large-scale manner remains a significant challenge. Herein, we report a simple method for preparing strong and tough silk fibers by feeding silkworms rare earth ion-modified diets. The resulting silk fibers exhibit significantly increased tensile strength and toughness, with average values of 0.85 ± 0.07 GPa and 156 ± 13 MJ m−3, respectively, and maximum values of 0.97 ± 0.04 GPa and 188 ± 19 MJ m−3, approaching those of spider dragline silk. Our findings suggest that the incorporation of rare earth ions (La3+ or Eu3+) into the silk fibers contributes to this enhancement. Structure analysis reveals a reduction in content and an improvement in orientation of β-sheet nanocrystals in silk fibers. X-ray photoelectron spectroscopy analysis confirms the chemical interaction between rare earth ions with β-sheet nanocrystals. The structural evolution and chemical interactions lead to the simultaneous enhancement in both strength and toughness. This work presents a simple, scalable, and effective strategy for producing ultra-strong and tough silk fibers with potential applications in areas requiring super structural materials, such as personal protection and aerospace.

Enhanced Thermal Stability of Red‐Emitting Sr2Si5N8:Eu2+ Phosphors from Triggered Applicable Trap Level via Rare Earth Ions Co‐Doping

AbstractTo solve the problem of thermal stability of the red‐emitting phosphor Sr2Si5N8:Eu2+ with great valuable luminescence performance, trivalent rare earth ions Ln3+ (Ln = Dy, Ho, Er, Tm, Nd, and Pr) are co‐doped into Sr2Si5N8: Eu2+ lattice to form thermally robust phosphors Sr2Si5N8:Eu2+,xLn3+(Lnx‐258, 0 ≤ x ≤ 0.05). The successful incorporation of rare earth ions in the crystal structure and the regulation of luminescent properties are proven by a variety of material characterization techniques and analysis. Although the co‐doping of the selected rare earth ions reduces the luminescence intensity of the phosphor, the Dy0.01‐258 sample still has a high external quantum efficiency (EQE) of 78.6%. More importantly, the co‐doping of Dy3+ with x = 0.01 significantly improves the luminescent thermal stability of phosphors at high temperature and the luminescence intensity of Dy0.01‐258 samples at 200 °C can be maintained at 94.7% of room temperature. The thermoluminescence spectrum shows that the defects brought about by co‐doping of Dy3+ with x = 0.01 introduce trap energy levels, which can compensate for the Eu2+ luminescence at high temperature. At the same time, the cathodoluminescence mapping and spectra show that the phosphor has a high saturation current under high‐energy electron bombardment, which indicates that this nitride phosphor also has the potential to be used in field emission display (FEDs). Based on its extraordinary EQE and thermal stability data, this nitride phosphor is the first‐rate among the red phosphors for pc‐wLEDs, and has excellent application prospects in FEDs.

Photocatalytic Degradation of RB dye via Cerium substituted SnO2 Photocatalysts

Scientists and citizens are highly worried about the dangers posed by ubiquitous presence of organic pollutants in water bodies as a result of industrial wastes, particularly phenolic compounds, organic dyes, and antibiotics. In the present study, a series of Ce-doped SnO2 (Ce = 0%, 0.5%, 1.5%, 3%, 5%) samples were synthesized by cost-effective sol–gel approach. XRD study confirms that synthesized samples have single phase crystalline nature. Using XRD, crystallite size have been calculated and found to be in the range 12.24–10.69 nm. Particle size obtained from HRTEM lying in the range 13.45–10.42 nm which was in well agreement with XRD. Raman, PL and XPS spectroscopy were used to identify defects/oxygen vacancies in the lattice. Magnetic investigations indicate that maximum magnetization was 24.44 × 10−3 emu/g for Ce 5%. UV-DRS further showed that band gap was reduced up to 5% Ce (Eg = 3.01 eV) in comparison to pure SnO2 (Eg = 3.71 eV) due to the formation of vacancy defects. In comparison to pure SnO2, Ce-doped SnO2 [Ce 5%] was found to have a maximum photodegradation efficiency of 96% in 60 min under UV irradiation for rose bengal dye. Henceforth, it can be concluded that SnO2 is a remarkable multifunctional material having uses in spintronic devices and as a catalyst for the degradation of organic dyes because of the improvement in ferromagnetic character and enhancement in catalytic behavior upon incorporation of rare-earth ions.

Investigation of the structural, photoluminescence properties, bioactivity and 5-fluorouracil delivery behavior of Dy3+ and Dy:Eu3+-doped bioactive glasses

Nowadays fluorescent biomaterials gained crucial interest in the biomedical field. Here we report the sol-gel synthesis and characterization of Dy3+ and Dy:Eu3+ co-doped bioactive glass powders. Structural, morphological, and photoluminescence (PL) characteristics of the prepared powders were investigated in detail. Additionally, in vitro hydroxyapatite forming ability and the anticancer drug (5-Fluorouracil) release behavior were investigated with respect to time. The influence of drug loading and delivery on the PL properties was monitored. Results showed that the highest PL intensity was obtained for the 5%Dy:Eu3+ co-doped glass samples. The incorporation of rare-earth ions into the glass network did not cause a significant difference in the structural properties. In vitro conversion experiments, performed in simulated body fluid, indicated that the incorporation of Dy3+ to the glass network enhanced the hydroxyapatite deposition however Dy:Eu3+ co-doping slightly decreased the bioactivity. Drug-loaded bioactive glass powders exhibited sustained drug release behavior to the phosphate buffered saline (PBS) medium. An increase was obtained in the fluorescence intensities for 5-FU-loaded samples followed by a further increase in emissions for the powders released drug to the PBS medium. The findings of the study may be useful for monitoring the degradation of bioactive glasses, conversion to hydroxyapatite as well as drug delivery after implantation.

The Effect of Annealing Temperature on the Structural and Magnetic Properties of Lanthanum Doped Cobalt Ferrite with the Bengawan Solo River Fine Sediment as the Source of Fe<sup>3+</sup>

The effect of annealing temperature on the structural and magnetic properties of a rare earth (La3+) doped cobalt ferrite with fine sediment from the Bengawan Solo River as the source of Fe3+ has been studied. Co-presipitation method is use for preparation nanoparticles whole this experiment. In order to modified the physical properties, the annealing treatment of 2000C, 3000C, and 4000C are performed. The obtained nanoparticles are characterized their structural properties by using X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. Then, magnetic properties evaluated by using Vibrating Sample Magnetometer (VSM). XRD results have shown that there is an increase in crystallite size with an increase in the given annealing temperature from 24.56 nm to 27.83 nm. The increase in crystallite size can be attributed to the increase in the internal energy of the crystal structure which promotes atomic diffusion. Meanwhile, there is a decrease in the value of the lattice parameter with an increase in the given annealing temperature. The decrease in lattice parameters with increasing crystallite size is generally due to the lattice parameters reaching a minimum energy with increasing crystallite size. The formation of La3+-O2- for the incorporation of rare earth ions into the lattice requires high energy. The FTIR results show an absorption that appears at the peak around ~580 cm-1. This indicates that the La3+ cation has successfully replaced the original structure of cobalt ferrite. The VSM results show that there is an increase in the value of Hc with an increase in the annealing temperature given from 100 Oe to 160 Oe. This is supported by the increase of anisotropy constant and increasing temperature annealing.

Novel Gemini Surfactant for Binding Eu(III)-Polyoxometalate into Hydrogels and Polymer Latexes.

The incorporation of rare-earth ions into polymer matrices can lead to useful materials in various fields such as biomarkers, lasers, luminescent devices, optical storage materials, and so on. Methods of incorporation are either extremely simple, such as mixing the polymer and the ion of interest in adequate solvents, or more sophisticated such as synthesizing predesigned monomers that contain the rare-earth ion or binding the ion on an already formed polymer chain. Cationic gemini surfactants represent a class of surfactants that can be used to incorporate metal-oxygen cluster compounds by means of strong electrostatic interactions. In this study, first, a novel cationic gemini surfactant having double bonds on both side chains was designed and prepared. After characterization, the surfactant was used to synthesize hydrogels with different degrees of crosslinking and also as a surfmer in emulsion polymerization of methyl methacrylate. The resulted polymer matrices were able to bind europium-polyoxometalate Na9[EuW10O36].32H2O. In case of luminescent lanthanide ions, changing the microenvironment around the metal ion also changes the intensity of some emission peaks as well as other luminescent parameters. Investigation of emission spectra of Eu3+ indicates a decrease in the symmetry of the microenvironment, when the polyanions pass from water to latex, to surfactant solution, and to hydrogel.

Rare-earth (Nd and Eu) induced structural transformation and optical properties of brownmillerite-type Sr2ScGaO5 oxide

Towards designing of new advanced optoelectronic materials, we have explored the synthesis of a series of rare earth (RE) substituted (Nd3+ and Eu3+) perovskite compounds, Sr2-x-yNdxEuyScGaO5+δ. The phase purities of three new compounds have been verified by Rietveld refinement, FESEM, EDS and Raman spectroscopic studies. The incorporation of RE ions at A-site leads to the structural transformation from brownmillerite Sr2ScGaO5 to cubic perovskite phase and the additional charge of the RE plays a crucial role for the nonstoichiometric oxygen vacancies in the host system. Interestingly, with the increment of europium dopant percentage, the optical properties significantly changes such as the colour of the emitting light moves from dark blue to red under UV irradiation as well as a change in their decay life time profile is also observed. The density functional theory calculations have been performed to understand the effect of oxygen vacancy in the electronic properties of the title compounds.

Highly red luminescent stabilized tetragonal rare earth-doped HfO2 crystalline ceramics prepared by sol-gel

We report high incorporation of rare earth ions (RE3+) into hafnia nanoparticles prepared by the sol–gel method and investigate how these dopants affect hafnia structure and phase transformation. An ethanolic suspension containing 5-nm hafnia nanoparticles was obtained from HfOCl2.8H2O in ethanol. Pure and 0.1–7 mol% Eu3+-doped materials afforded HfO2 monoclinic phase, whereas hafnia nanoparticles added with 10 and 20 mol% Eu3+ were stabilized in the tetragonal phase. Structural evolution of the nanoparticles was analyzed by Eu3+ luminescence spectroscopy and excited level lifetimes. The emission spectra in the visible region showed an increase of the Eu3+ site symmetry due to hafnia phase transformation from monoclinic to tetragonal upon increasing Eu3+ concentration. Concentration quenching, followed by lifetime measurements, occurred at high Eu3+ concentration (20 mol %). The hafnia tetragonal phase was stabilized with non-optically active La3+ (a fixed concentration of 10 mol %), co-doped with a lower concentration of Eu3+ ions (from 0.1 to 3 mol %). This strategy ensured that Eu3+ luminescence in tetragonal hafnia was intense and prevented quenching by the high Eu3+ concentration. In this sense, the hafnia structure and emission properties can be tailored by the RE3+ concentration, so that an interesting material for applications in photonics and biophotonics can be achieved.

Optical and Structural Characteristics of Rare Earth-Doped ZnO Nanocrystals Prepared in Colloidal Solution

ZnO nanocrystals doped with Nd, Gd, and Er were synthesized using a soft chemical process in ambient atmosphere. Pseudospherical and hexagonal nanocrystals (NC) of the wurtzite phase with a mean size of (7.4 ± 1.7) nm were obtained. The presence of rare earth (RE) dopants was confirmed by X-ray fluorescence (XRF) spectroscopy. The ZnO nanocrystals exhibited simultaneously narrow excitonic- and broad trap/surface-related photoluminescence (PL), both of which were affected by doping with RE atoms. Doping reduced the total PL intensity, suppressing the excitonic emission by a greater extent than the broad band PL. Also, doping resulted in a blue shift of the trap/surface-related emission, while the energy of the excitonic peak remained unchanged. Resonant Raman spectra additionally confirmed the wurtzite phase of ZnO NCs and revealed a shift of the A1-LO mode towards lower frequency upon doping that could be caused by the mass effect of RE atoms, point defects, and increases in charge carrier concentration. Fitting of the spectra with Voigt profiles showed better results with two surface optical (SO) phonon modes that were previously theoretically predicted for the wurtzite ZnO phase. The influence of RE doping on PL and Raman spectra can be explained by the incorporation of RE ions into the ZnO nanostructures, where the dopants act as non-radiative defects.

Intense and broadband mid-infrared emission by nano-crystallization of rare‐earth doped oxyfluoride glass-ceramic

Transparent oxyfluoride glass ceramics (GCs) comprised of a uniform oxide glass phase and a well-distributed fluoride crystal phase are regarded as suitable optical gain materials because of the combination of facile fabricability of glass and low phonon energy of nanocrystals. Here, oxyfluoride GCs containing NaYF4: Er3+/Ho3+/Dy3+ nanocrystals were controllably prepared. Due to the preferential incorporation of rare-earth ions into NaYF4 nanocrystals with low phonon energy and the efficient energy transfer between active ions, enhanced and broadband mid-infrared (MIR) emission at 2.5–3.3 µm was obtained from the GCs, which was nearly unobserved in precursor glass (PG) because of the high phonon energy of glass matrix. Compared with Er3+ singly-doped sample, the full width at half maximum (FWHM) is more than 3 times broader in Er3+/Ho3+/Dy3+ triply-doped sample. Furthermore, by the match of the refractive index of glass with NaYF4 nanocrystal, transparent GCs with average crystal size of 80 nm and high transmittance over 80% were achieved simultaneously. The desirable optical properties endow the GCs with potential applications in MIR broadband tunable lasers.

Crystal filament blended m-Bi(Er3+-Yb3+)VO4 fibers with temperature feedback and high-efficiency photocatalysis performance

Bi(Er3+-Yb3+)VO4 fibers prepared by the iterative electrospinning process have excellent crystal filament compatibility. Compared with traditional photocatalytic materials, fibers in our work are admirable in some aspects including large specific surface area, strong three-dimensional weaving capacity, high solar energy utilization rate, high reproducibility, and controllable structure. The working temperature of the catalytic degradation process is monitored and fed back in real time by 2H11/2 →4I15/2 and 4S3/2 →4I15/2 radiation transitions of Er3+ with excellent sensitivity. Photocatalytic efficiency is greatly improved by broadening the photoresponse range of BiVO4 and inhibiting the recombination of photo-generated charges, which is attributable to the successful incorporation of rare earth ions. The maximum degradation efficiency of methylene blue (MB) is 98.7% and the degradation constant K is as high as 0.116 min−1 under simulated sun-light irradiation and it also has the same degradation trend under near-infrared (NIR) light irradiation. In general, highly efficient catalytic fibers with sensitive temperature feedback performance provide a new perspective for the application of multifunctional photocatalytic materials in extremely harsh environments to address pressing energy and environmental challenges.

Mid-Infrared, Green and Red Emission in Ho3+ - Er3+ Co-Doped Phosphate Glasses

Over the past decades, phosphate glasses show ample advantages in laser technology because of their excellent optical properties like a low glass transition temperature, low phonon energy, large infrared transmission window, and high gain density. The inclusion of lead and alkali earth metals to these phosphate glasses also improves the chemical durability of glasses, which have more advantages in smart cards, medical applications, and micro-batteries. The optimum environment for chemical durability and incorporating rare earth ions can be achieved by the interaction between sulphate and phosphate ions. Moreover, phosphate glasses mixed with alkali sulphate provides scope for micro battery applications. The presence of network modifiers like Pb2+, Zn2+ in phosphate glasses introduces structural modifications and increases the number of non-bridging oxygens (NBOs) in glass network. The metal oxides like PbO, Bi2O3 makes phosphate glass suitable for rare earth ion incorporation by softening the glass and provides better distribution by controlling the formation of clusters. The wide variety of rare earth ions in the phosphate glasses leads to wide range of applications in optoelectronic devices.To overcome the difficulty associated with lack of a useful absorption band at 980 nm of Ho3+ ion (easy excitation by commercial laser diode (LD)), rare earth ions such as Tm3+, Yb3+, and Er3+ can be introduced. Especially, among them, Er3+ exhibit strong absorption at 980 nm. Due to the narrower energy gap between Er3+: 4I13/2 and Ho3+: 5I7 states, the emission of Ho3+ ions can be enhanced by addition of Er3+. So, the Er3+/Ho3+ co-doped glasses have promising applications in mid-infrared (MIR) laser applications with 980 nm LD. In view of this, the set of the Er3+/Ho3+ co-doped sodium-sulfo lead phosphate glasses was prepared with the molar composition of (20-x-y) Na2SO4-20PbO-60P2O5-xEr2O3-yHo2O3 (x=0.5, y= 0.2, 0.4, 0.6, 0.8, 1.0 mol %) named as GEH-y glass and coded as GExHy. To explore various possible applications, all prepared glasses are characterised by EDS, XRD, FTIR, absorption, photoluminescence and lifetime profiles. All results are computed and few of them are compared with other glasses.We present results focused on both mid infrared and visible emission properties of Er3+/Ho3+ions in sodium-sulfo lead phosphate (GExHy) glasses. These materials exhibit simultaneously DC (down-conversion) and UC (up-conversion) photoluminescence (PL) by excitation at 379 nm and 980 nm. The favourable concentration of Ho2O3 was estimated from the analysis of NIR PL spectra for Ho3+: 2.0 mm and Er3+: 1.5 mm. In GExHy glasses, the increase in intensity near 2.0 mm with decrease in intensity at 1.5 mm infers to energy transfer process between Er3+ and Ho3+ ions.Under lexc= 379 nm the Er3+ ions are pumped to the 4G11/2 excited state and depopulate {via multi phonon relaxation MPR1} at lower 4S3/2, 2H11/2, and 4F9/2 levels and then relaxed to the 4I15/2 ground state by emitting weak and strong green emission bands along with weak red emission related to 4S3/2→4I15/2 (522 nm), 2H11/2→4I15/2 (544 nm), and 4F9/2→4I15/2 (657 nm) transitions, respectively. The up-conversion energy transfer (ET) analysis with 980 nm LD excitation, undergoes the following mechanism: Ground state absorption (GSA) : Er: 4I15/2 + hν → Er: 4I11/2 Excited State Absorption (ESA1) : Er: 4I11/2+ hν → Er: 4F7/2 Excited State Absorption (ESA2) : Er: 4I13/2 +hν → Er: 4F9/2 CR1 (Cross Relaxation) : Er: 4I11/2+Ho: 5I6→ Er: 4I15/2+Ho: 5F4 CR2 (Cross Relaxation) : Er: 4I13/2+Ho: 5I6→ Er: 4I15/2+Ho: 5F5 ET1: Er: 2S3/2+Ho: 5I8→ Er: 4I15/2+Ho: 5S2+5F4 ⇒ Ho: 5S2+5F4 → 5I8 (545 nm) ET2 : Er: 4F9/2+Ho: 5I8→ Er: 4I15/2+Ho: 5F5 ⇒ Ho: 5F5→5I8 (659 nm) MPR2: Ho: 5S2+5F4 → 5F5 ET3: Er: 4I11/2+Ho: 5I8→ Er: 4I15/2+Ho: 5I6 ⇒ Er: 4I13/2 → 4I15/2 (1554 nm) ET4: Er: 4I13/2+Ho: 5I8→ Er:4I15/2+Ho Fig. 1 Schematic energy level diagram of GE0.5H0.8 glass.The maximum energy transfer efficiency of GExHy samples is 75.5% and with the increase of Ho3+ ions, the lifetime decay has been reduced from 5.06 ms to 1.24 ms. The absorption and stimulated emission cross-sections of Er3+:1.5 mm and Ho3+: 2.0 mm were calculated. Moreover, the FWHM × σemi was estimated for Ho3+:5I7→5I8 transition to estimate the probable MIR laser emission. The CIE color coordinates were estimated from both DC and UC PL spectra. All the results indicated that the prepared GExHy glasses have promising material applications in mid-infrared solid-state lasers and telecommunications. In addition, efficient green and red emission makes these glasses attractive for the phosphor applications. Figure 1

Ytterbium-implanted photonic resonators based on thin film lithium niobate

We introduce our design, simulation, and fabrication for cm-long waveguides and micro-ring resonators based on fully-etched thin-film lithium niobate on insulator (LNOI) incorporated with rare earth ions. We implant ytterbium ions (Yb3+) into the crystalline host and study their optical properties at 4 K temperature. We measure an intrinsic optical quality factor of higher than 2×106 after postimplantation annealing. We characterize the photoluminescence spectrum, lifetime, and absorption of Yb3+ ions. Incorporation of rare earth ions into LNOI as a crystalline and nonlinear photonic element may enable the development of multi-functional quantum photonic devices capable of generating, transducing, manipulating, and storing of quantum optical information.

Computer modelling of Bi12SiO20 and Bi4Si3O12: Intrinsic defects and rare earth ion incorporation

Defect properties of Bi12SiO12 and Bi4Si3O12 compounds were investigated using atomistic computer modelling techniques based on energy minimisation. Interatomic potentials obtained by empirical fitting reproduce the lattice parameters for both materials and the available elastic and dielectric constants with reasonable accuracy. The relative stability of the phases and the intrinsic defects of both phases are predicted. A new methodology is used for calculating solution energies for rare earth doping which takes doping concentration into account.

Non-Linear Optical Properties of Er3+-Yb3+-Doped NaGdF4 Nanostructured Glass-Ceramics.

Transparent oxyfluoride glass–ceramics containing NaGdF4 nanocrystals were prepared by melt-quenching and doped with Er3+ (0.5 mol%) and different amounts of Yb3+ (0–2 mol%). The selected dopant concentration the crystallization thermal treatments were chosen to obtain the most efficient visible up-conversion emissions, together with near infrared emissions. The crystal size increased with dopant content and treatment time. NaGdF4 NCs with a size ranging 9–30 nm were obtained after heat treatments at Tg + 20–80 °C as confirmed by X-ray diffraction and high-resolution transmission electron microscopy. Energy dispersive X-ray analysis shows the incorporation of rare earth ions into the NaGdF4 nanocrystals. Near-infrared emission spectra, together with the up-conversion emissions were measured. The optical characterization of the glass–ceramics clearly shows that Er3+ and Yb3+ ions are incorporated in the crystalline phase. Moreover, visible up-conversion emissions could be tuned by controlling the nanocrystals size through appropriated heat treatment, making possible a correlation between structural and optical properties.

Precipitation of rare-earth ions doped pyrochlore nanocrystals in glasses

Pyrochlore structured nanocrystals could have large solubility of rare-earth ions, making them promising for application in various light emitting materials and immobilization of radioactive nuclear waste. In this work, rare-earth doped pyrochlore structured nanocrystals were precipitated in glasses using melt-quenching and subsequent thermal treatment. Lu3+ along with Yb3+ and Er3+ ions were doped into the glasses, and Yb3+ and Er3+ were employed as probes to illustrate the incorporation of rare-earth ions into pyrochlore nanocrystals. X-ray diffraction patterns and transmission electron microscopy showed the precipitation of pyrochlore nanocrystals with average diameters of 13–15 nm upon thermal treatment. Energy dispersive spectroscopy, absorption spectra, visible and near-infrared emission spectra all confirmed the incorporation of rare-earth ions into these pyrochlore structured nanocrystals.