Eu Concentration Research Articles

Fabrication of metal-organic frameworks with trimesic linkers for europium adsorption and recovery from aqueous solutions

This work reports on the effective sequestration of Eu(III) ions from aqueous solutions using three types of metal-organic frameworks (MOFs) constructed from benzene-1,3,5-tricarboxylic acid (H3BTC) linker and Ca2+, Cu2+, or Al3+ metal nodes. The MOFs possessed an exceptionally high Eu adsorption capacity of 635 (91% removal), 642 (92% removal), and 628 mg g−1 (90% removal) for Cu-BTC, Ca-BTC, and Al-BTC, respectively, at pH 7 for an initial Eu concentration of 350 mg L−1. The MOFs were hydrolytically stable and possessed a high Eu adsorption capacity in a wide pH range of 4–8. While the pseudo-second-order model explained the adsorption kinetics, the adsorption process followed the Langmuir-Freundlich isotherms. The analysis confirmed that the Eu adsorption process was governed by chemical interactions between the carboxylic acid/carboxylate group and Eu(III) ions via complexation or ion exchange mechanism. A multi-metal adsorption study confirmed a preferential adsorption behaviour for trivalent lanthanides over divalent cations due to comparatively stronger interactions between Ln3+ ions and carboxylate groups. The XPS findings suggested Eu−OOC and Eu(OH)3 formed over the MOFs' surface after Eu adsorption. These MOFs were effectively regenerated for multiple cycles using 0.1 mol L−1 EDTA solution. Thus, the study demonstrated low-cost MOFs with superior regeneration capabilities for the capture of Eu(III) ions from waste solutions.

Rapid synthesis of BaMoO4 :Eu3+ red phosphors using microwave irradiation.

This study synthesized BaMoO4:Eu3+ red phosphors using the microwave method. In addition, the phase composition, morphology, and luminescence properties of the red phosphors were characterized using X-ray diffraction, field-scanning electron microscopy, and photoluminescence spectroscopy. The results revealed that doping red phosphors with different concentrations of Eu3+ does not change the crystal structure of the matrix material. The BaMoO4 :Eu3+ phosphors exhibited micron-scale irregular polyhedra, which could be excited by ultraviolet light with a wavelength of 395 nm to induce red-light emission. The optimal dosage of Eu3+ was 0.08, and the chromaticity coordinates of BaMoO4 :0.08Eu3+ phosphors were (0.5869, 0.3099). White light-emitting diode (w-LED) devices manufactured by using a combination of BaMoO4 :0.08Eu3+ phosphor and commercially available phosphors exhibited good white-light emission under the excitation of an ultraviolet chip. The BaMoO4 :0.08Eu3+ red phosphors that rapidly synthesized under the microwave field are expected to be used in w-LED devices.

A practical method for assigning uncertainty and improving the accuracy of alpha-ejection corrections and eU concentrations in apatite (U–Th) ∕ He chronology

Abstract. Apatite (U–Th) / He (AHe) dating generally assumes that grains can be accurately and precisely modeled as geometrically perfect hexagonal prisms or ellipsoids in order to compute the apatite volume (V), alpha-ejection corrections (FT), equivalent spherical radius (RFT), effective uranium concentration (eU), and corrected (U–Th) / He date. It is well-known that this assumption is not true. In this work, we present a set of corrections and uncertainties for V, FT, and RFT aimed (1) at “undoing” the systematic deviation from the idealized geometry and (2) at quantifying the contribution of geometric uncertainty to the total uncertainty budget for eU and AHe dates. These corrections and uncertainties can be easily integrated into existing laboratory workflows at no added cost, can be routinely applied to all dated apatite, and can even be retroactively applied to published data. To quantify the degree to which real apatite deviates from geometric models, we selected 264 grains that span the full spectrum of commonly analyzed morphologies, measured their dimensions using standard 2D microscopy methods, and then acquired 3D scans of the same grains using high-resolution computed tomography (CT). We then compared our apatite 2D length, maximum width, and minimum width measurements with those determined by CT, as well as the V, FT, and RFT values calculated from 2D microscopy measurements with those from the “real” 3D measurements. While our 2D length and maximum width measurements match the 3D values well, the 2D minimum width values systematically underestimate the 3D values and have high scatter. We therefore use only the 2D length and maximum width measurements to compute V, FT, and RFT. With this approach, apatite V, FT, and RFT values are all consistently overestimated by the 2D microscopy method, requiring correction factors of 0.74–0.83 (or 17 %–26 %), 0.91–0.99 (or 1 %–9 %), and 0.85–0.93 (or 7 %–15 %), respectively. The 1σ uncertainties in V, FT, and RFT are 20 %–23 %, 1 %–6 %, and 6 %–10 %, respectively. The primary control on the magnitude of the corrections and uncertainties is grain geometry, with grain size exerting additional control on FT uncertainty. Application of these corrections and uncertainties to a real dataset (N=24 AHe analyses) yields 1σ analytical and geometric uncertainties of 15 %–16 % in eU and 3 %–7 % in the corrected date. These geometric corrections and uncertainties are substantial and should not be ignored when reporting, plotting, and interpreting AHe datasets. The Geometric Correction Method (GCM) presented here provides a simple and practical tool for deriving more accurate FT and eU values and for incorporating this oft neglected geometric uncertainty into AHe dates.

Adsorption of actinides (Ⅲ) and lanthanides (Ⅲ) on silica-based BCPDTPA resin: Kinetics, thermodynamics, and isotherms

To minimize the long-term radiological risk and improve the accuracy of radioactive analysis, isolation of trivalent actinides and lanthanides is very necessary and much more challenging due to their similar chemical properties. Herein, the adsorption performance and mechanism of a novel porous BCPDTPA/SiO2-P extraction resin towards trivalent actinides (Am) and lanthanides (Eu) was investigated. The effects of adsorption parameters such as contact time, HNO3 concentration, temperature, and Eu concentration on the adsorption were conducted by batch adsorption experiments. The adsorption mechanism of Am(Ⅲ) and Eu(Ⅲ) by BCPDTPA/SiO2-P resin was elucidated based on kinetics, thermodynamics, and isotherms analysis. The results showed that BCPDTPA/SiO2-P resin has a high affinity for Am(Ⅲ) compared to Eu(Ⅲ) within the range of experimental conditions. Kinetic studies revealed that the resin was in accordance with the pseudo-second-order equation by chemisorption as the rate-limiting step of the adsorption process. Thermodynamic parameters indicated that the adsorption was spontaneous and endothermic process. The adsorption isotherm followed the Freundlich isotherm model. As a result, the use of BCPDTPA/SiO2-P resin as a stationary phase for chromatographic separation of actinides(Ⅲ)/lanthanides(Ⅲ) can be expected due to its clear adsorption mechanism and selectivity.

Radiogeochemistry, mineralogy, lithology, radiogenic heat production, and health implication using airborne radiometric data of Ilesha and its surroundings.

The current study analyzed and interpreted airborne radiometric data from Ilesha's basement complex rock and its surroundings. At the surface, the concentrations of the most frequent primordial radionuclides notably K, elemental concentration of uranium eU, and elemental concentration of thorium eTh were measured. The weighted mean elemental and activity concentrations were 0.85%, 2.75ppm, 10.22ppm, and 267.54Bqkg-1, 34.41Bqkg-1, 41.51Bqkg-1 for 40K, 238U, and 232Th, respectively. The low concentration of 40K was certainly due to the effects of weathering, kaolinization of granites, and pedogenesis activities. The abundance of uranium was ascribed to the availability of uranium minerals such as allanite, apatite, and sphene with accessories minerals, while that of thorium was due to minerals such as cheralite, thorite, uranothorite, thorianite, and uranothorianite with accessories minerals. The RPHR weighted mean 1.48 µWm-3 compared to the earth's crust mean between 0.8 and1.2 µWm-3 was higher due to significant presence of gneiss rocks in all the studied profiles. Radiological hazard, in particular, dose rates, external hazard index, internal hazard index, radium equivalent, annual gonadal dose, effective dose dispensed to various organs of the body were computed to determine the deleterious effects of rocks in the area. The weighted means of annual gonadal dose of 363.98 µSv y-1 and outdoor 0.91 × 10×3 and indoor 1.65 × 10-3 excessive life cancer risks were more than the global average 300 µSv y-1, 0.29 × 10-3 and 1.16 × 10-3. As a result, proper surveillance is required in the area in order to prevent epidemics occurrence in future.

Two Distinct Fractional Crystallization Mechanisms of A-Type Granites in the Nanling Range, South China: A Case Study of the Jiuyishan Complex Massif and Xianghualing Intrusive Stocks

The petrogenesis of A-type granites with different occurrences in the Nanling Range remains unclear. In this study, a case study of the Jiuyishan complex massif and Xianghualing intrusive stocks was conducted to determine this problem. The Jiuyishan complex massif is composed of four units (Jinjiling, Pangxiemu, Shaziling and Xishan). These four units have similar zircon U-Pb ages of approximately 153 Ma, with high Zr + Nb + Ce + Y contents (>350 ppm), high 10,000 Ga/Al ratios (>2.6), and a high crystallization temperature, indicating A-type affinities. They show a gradual change in lithology and geochemistry, implying a fractional crystallization process. These units also have similar εNd(t) values (−8.2 to −5.8) and zircon εHf(t) values (−7.5 to −2.2) except for the Shaziling MMEs (mafic microgranular enclaves) (−14.2 to 4.8), demonstrating their lower crustal source. However, the Shaziling unit may have contributed mantle-derived magma based on the geochemical data of its hosted MMEs. In comparison, the two Xianghualing intrusive stocks have similar geochemical features but exhibit highly evolved features (high Rb, U, Y, Ta and Nb contents and low Eu, Ba, Sr, P, Ti, Ca, Mg and Fe contents, with V-shaped REE distribution patterns). They have different zircon U-Pb ages of approximately 160 Ma and 155 Ma. The two stocks also have similar whole-rock εNd(t) values (−6.5 to −5.7) and zircon εHf(t) values (−7.6 to −2.7) and equally illustrate a lower crustal source region. Combining with their vertical zonation, they may have experienced remarkable fractional crystallization with possible assimilation processes. We propose that the Jiuyishan complex and Xianghualing stocks have two distinct fractional crystallization mechanisms during their formation. The Jiuyishan complex was formed by in situ crystal mush fractionation, while the Xianghualing stocks were formed by flowage differentiation during magma ascent or gravitational settling during magma solidification after emplacement. However, more than one mechanism affected the fractional crystallization processes of these granitic rocks.

Europium doped titanium dioxide nanocrystalline: synthesis, structure and optical properties

Abstract
 Uniform, spherical-shaped TiO2: Eu nanoparticles with different doping concentrations were synthesized using the sol-gel method. The structural, morphology, optical, luminescent, and surface properties of the samples were investigated at different Eu3+ concentration. The morphology, crystalline structure, and chemical composition of the samples were characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The X-ray diffraction results reveal that the obtained powder nanoparticles consist of a single phase tetragonal structure. The crystallite sizes calculated by utilizing Scherrer’s equation were found in the range of 18.94 – 7.77 nm for TiO2:Eu samples annealed at 550οC. The SEM images reveal an irregular agglomerated morphology indicating a decrease in particle size with an increase in Eu3+ concentration. X-ray photoelectron spectroscopy (XPS) high resolution spectra of the Ti-2p peak confirmed that Ti atoms were in a doubly ionized state, and the deconvolution of the O1s XPS peak show the presence of oxygen related defects in the sample. EDS results confirm a systematic increase of Eu content in the as-prepared samples with the increase of europium concentration. Incorporation of europium in the titania particles induces a structural deformation and a blueshift of their absorption edge. The luminescence intensity increases with Eu3+ concentration up to 3 mol% and then quenched. While the PL emission of the as-grown samples is dominated by the 5D0 - 7Fj transition of Eu3+ ions, the emission intensity reduces drastically after thermal annealing due to outwards segregation of dopant ions.
 Keywords: Titanium dioxide; Photoluminescence Spectroscopy; XPS; Nanocrystalline; Anatase; Rutile. 

Blue light induced red phosphors Sr2CeO4:Eu3+ through co-doping with M2+ (Mg, Ba, Ca) and spectroscopic properties applied in WLEDs

In the present work, A series of Sr2CeO4:xEu3+ (x = 0.15, 1, 2, 5 mol%) (SCO:xEu3+) and co-doped with different divalent metal ions (M2+: Mg, Ca, Ba) phosphors were successfully synthesized through traditional hydrothermal method. All the samples performed pure Sr2CeO4 phase. The absorption spectra show that an overlap between Ce4+–O2- CTS band and Eu3+ ions results in the energy transfer from the matrix to the emitting center. With the concentration of Eu3+ ion increasing, the phosphors exhibit orange red emission, and the highest intensity was achieved when the Eu3+ concentration was 2 mol%. The energy transfer mechanism would be dipole–dipole interaction. Furthermore, when the concentration of Eu3+ ion is at 2 mol%, the samples co-doped with M2+ ion performed intense red emission of Eu3+ ion under 467 nm excitation, which is ascribed to M2+ ions disturbed the anisotropic structure to create defects so that make much more efficient energy transfer from Ce-O band to Eu3+ ions. Moreover, CIE chromaticity showed SCO:2%Eu3+/2%M2+ phosphors performed pure red warm light. The above results suggest that SCO:2%Eu3+/2%M2+ can be of potential as red-emitting phosphor for blue-excitation WLEDs.

Enhancement of electrical properties in Eu-doped PMN-PT thin films prepared by sol-gel method

Europium-modified Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 (xEu-PMNT) (x = 1 %, 2 %, 3 %, 4 %) thin films have been deposited on Pt/Ti/SiO2/Si substrates via sol-gel process. The purpose of this present work was to investigate Eu doping-dependent crystal orientation, microstructure, and piezoelectric behaviors of the Eu-PMNT films. X-ray diffraction (XRD) analysis shows that PMNT films exhibit (100) preferred orientation when Eu content less than 3 %, and the film doped with 4 % show (110) polycrystalline orientation accompanied by pyrochlore phase. Increasing grain size and dense microstructure are detected by Scanning electron microscope (SEM) characterization as increasing Eu concentration to 2 %. For the film with 2 % Eu-doped, superior dielectricity (εr = 1204.5, tanδ = 0.055) measured at 1 kHz and ferroelectricity (2Pr = 21.6 μC/cm2, 2Ec = 73 kV/cm) are achieved. Moreover, an enhanced piezoelectric constant (e31) of 8.2 C/m2 is obtained in the PMN-PT film doped with 2 % Eu.

Contrasting thermal histories in the Dom Feliciano Belt triggered by magmatism related to the Paraná-Etendeka LIP and fracture zone proximity

The present-day southern Brazilian continental margin rests on top of the Dom Feliciano Belt (DFB) and adjacent cratons. This belt formed through the collision of the Rio de La Plata, Kalahari, Paranapanema, Congo and Luis Alves paleoplates in the Neoproterozoic. Several low-temperature thermochronology works were executed in the area, although none of them demonstrated how the basement temperature of the entire DFB evolved through time. To this end, this work aims to provide new Apatite Fission Track (AFT) and Apatite (UTh)/He (AHe) ages for samples collected in the Catarinense Shield, in the northern DFB, and to perform inverse modeling in those samples. Besides, the collection of the basement temperature of 128 locations across the entire belt and adjacent cratons provided thermal information to create inverse-distance weighted interpolation maps documenting the progression of the temperature from 360 to 30 Ma. New AFT ages range from 126.6 ± 24.1 to 60.3 ± 6.03 Ma, whereas AHe ages span from 153.0 ± 9.2 to 62.5 ± 3.7 Ma. Mean track lengths are short to medium, suggesting complete thermal annealing of apatite crystals. Apatite single-grain eU concentration range from 4.5 to 96 μg/g and display a sparse correlation with AHe ages. Interpolation maps evidence a contrasting temperature evolution of the northern DFB and bordering cratons relative to the southern segment and surrounding cratons. Near-surface exposure of the basement in the northern segment was possibly much earlier than in the south, followed by partial burial by the sedimentary successions of the Paraná Basin. The emplacement of volcanic rocks of the Paraná-Etendeka Large Igneous Province and associated dyke swarms and alkaline volcanic plugs related to the Florianópolis Fracture Zone raised and sustained higher basement temperatures until 30 Ma, resetting low-temperature thermochronometers in the northern DFB, which was minor to absent in the southern DFB.

Toward quantification of hypoxia using fluorinated EuII/III-containing ratiometric probes

Hypoxia is a prognostic biomarker of rapidly growing cancers, where the extent of hypoxia is an indication of tumor progression and prognosis; therefore, hypoxia is also used for staging while performing chemo- and radiotherapeutics for cancer. Contrast-enhanced MRI using EuII-based contrast agents is a noninvasive method that can be used to map hypoxic tumors, but quantification of hypoxia using these agents is challenging due to the dependence of signal on the concentration of both oxygen and EuII. Here, we report a ratiometric method to eliminate concentration dependence of contrast enhancement of hypoxia using fluorinated EuII/III-containing probes. We studied three different EuII/III couples of complexes containing 4, 12, or 24 fluorine atoms to balance fluorine signal-to-noise ratio with aqueous solubility. The ratio between the longitudinal relaxation time (T1) and 19F signal of solutions containing different ratios of EuII- and EuIII-containing complexes was plotted against the percentage of EuII-containing complexes in solution. We denote the slope of the resulting curves as hypoxia indices because they can be used to quantify signal enhancement from Eu, that is related to oxygen concentration, without knowledge of the absolute concentration of Eu. This mapping of hypoxia was demonstrated invivo in an orthotopic syngeneic tumor model. Our studies significantly contribute toward improving the ability to radiographically map and quantify hypoxia in real time, which is critical to the study of cancer and a wide range of diseases.

Dielectric, electrical conductivity, and photoluminescence properties of CaGa2S4:Eu2+ added high-density polyethylene

Dielectric permittivity, electrical conductivity, and photoluminescence properties of high-density polyethylene with the additive of CaGa2S4:Eu+2 are studied. It was shown that dielectric permittivity and electric conductance increase with increasing filler concentration at all temperatures. In this case, conductivity has a hopping mechanism described by the Josher theory. The corresponding exponent parameter and activation energy slightly decrease with increasing filler concentration. The experimental data of dielectric permittivity are compared with the Maxwell–Garnett theory. It is also shown that the position of maximum of photoluminescence does not change with an increase in the concentration of Eu2+ ions and equals to about 550 nm. In this case, its intensity is maximal at the concentration of the filler is 5 mol. %.

Microstructure and Physical Properties of (Eu, Ni) Co-Doped BiFeO3 Materials

BiFeO3 (BFO) and Bi1-x Eu x Fe0.975Ni0.025O3 (x = 0, 0.025, 0.05, 0.075, 0.10) materials were synthesized by sol-gel method. The structural, optical, ferromagnetic, and ferroelectric properties of all samples were systematically investigated using different techniques. Analysis results of XRD showed that all samples were crystallized in the rhombohedral structure with R 3C space group. The crystal lattice parameters were a = 5.563 Å, c = 13.833 Å and crystal size is L XRD = 519 Å for BiFeO3 materials whereas the a, c, and L XRD of (Eu, Ni) co-doped samples decreased with Eu concentration. Raman scattering spectra were used for confirming the substitution of Eu3+ ions into Bi-sites. Fluorescence spectra showed the enhancement of characteristic emission peaks with Eu concentration. The BFO exhibited weak ferroelectric behavior with a maximum polarization of P s = 12.698 μC cm−2, remnant polarization of P r = 7.351 μC cm−2. Ferroelectric properties of the (Eu, Ni) co-doped samples were significantly enhanced. The BFO material exhibited a weak ferromagnetic behavior with saturation magnetization of M s = 0.036 emu g−1, remnant magnetization of M r = 0.004 emu g−1. The ferromagnetic properties of sample were also improved with presence of (Eu, Ni) dopants. The origin of the improvement in ferromagnetism, ferroelectricity, and fluorescence were also thoroughly discussed.

Regulation of luminescence properties of Gd2O3–B2O3–SiO2–Na2O–Al2O3 glasses by the content of Eu3+

Regulation of luminescence properties of Gd2O3–B2O3–SiO2–Na2O–Al2O3 glasses by the content of Eu3+

Luminescent ionic lattice occupation and wide tunable emission spectra of La2MgZrO6:Bi3+,Eu3+ double perovskite phosphors for white light LED

La 2 Mg 1– x /2 Zr 1– x /2 O 6 : x Bi 3+ ( x = 0.01–0.035, abbreviated as LMZ:Bi 3+ ) and La 2– y Mg 0.99 Zr 0.99 O 6 :0.02Bi 3+ , y Eu 3+ ( y = 0.1–0.11, abbreviated as LMZ:Bi 3+ ,Eu 3+ ) double-perovskite phosphors were prepared through high-temperature solid-phase method. The emission spectrum of LMZ: x Bi 3+ ( x = 0.01–0.035) phosphors excited at 353 nm is asymmetric in the range between 375 and 650 nm, showing strong green light. There are two luminescent centers of [Mg1/Zr2–O 6 ] and [Mg2/Zr1–O 6 ] for Bi 3+ occupation, which were analyzed through different excitation wavelengths, Gaussian fitting peaks, fluorescence decay curves and Rietveld refinement of powder X-ray diffraction data. Through deep study of the luminescent lattices in the LMZ matrix, the green to blue tunning-emission is observed by different excitation wavelengths. In addition, red emission is obtained by co-doping Bi 3+ /Eu 3+ , and adjustable emission was investigated by changing the content of Eu 3+ in the co-doped phosphor formulation, so it is converted from green emission to red emission. The above results demonstrate how to tune emission color by co-doping rare earth ions in the double perovskite phosphor, which is attractive for future applications. The Gaussian deconvolution of the emission spectrum of LMZ:Bi phosphors was performed to obtain two sub-Gaussian components, and the selective site occupancy of Bi 3+ was analyzed. By co-doping Bi 3+ and Eu 3+ , the luminescence intensity of Eu 3+ can be effectively improved.

The roles of dopant concentration and defect states in the optical properties of Sr2MgSi2O7:Eu2+, Dy3+

The blue-emitting Sr2MgSi2O7:Eu2+,Dy3+ was prepared by sol-gel method. The effects of dopant concentration on crystal structure, photoluminescence and afterglow properties were studied. Based on First-principles calculations, the formation difficulty and electronic structures of intrinsic defects and the external defects caused by doping Eu, Dy were predicted, and the defect-dominated persistent luminescence mechanism was proposed. The results showed that when the content of Eu2+ reached 0.03 mol%, Sr2MgSi2O7:Eu2+,Dy3+ had the best luminescence performance. After exceeding this content, the concentration quenching caused by electric dipole-dipole interaction would occur, leading to a decrease in luminescence intensity. The oxygen vacancy as an intrinsic defect was more easily formed in Sr2MgSi2O7. The impurity levels in the forbidden band, which were introduced by oxygen vacancies and Dy doping defects, can effectively capture and release Eu electrons. It is beneficial to prolong the afterglow duration of Eu 4f65d1→Eu 4f7. This work reveals the electron transition and capture paths in the luminescence of Sr2MgSi2O7:Eu2+,Dy3+, which has reference significance for designing defect structures and optimizing optical properties.

Contraints on Petrogenesis and Fe Fertility of Intrusive Complexes in the Han–Xing Region, North China Craton from Apatite Geochemistry

The Han–Xing (Handan–Xingtai) region is famous for its endowment of skarn iron deposits in China. These deposits are mainly spatially and genetically associated with diorite rocks, but these rocks show different Fe ore potential. Major and trace elements composition of apatite from the Kuangshan and Fushan diorite complexes were investigated to explore the potential of apatite as a proxy of petrogenesis and Fe fertility of these rocks. All the investigated apatite grains are identified as fluorapatite, which is typical for magmatic apatite. The Sr, Y, Mn, and Heavy Rare Earth Elements (HREE) contents of apatite in the Kuangshan diorite complex are positively correlated with the increase of melt SiO2 content compared to that in the Fushan diorite complex. Apatite geochemistry indicates that magmas of the Fushan complex mainly experienced the fractional crystallization of hornblende in the deep crustal reservoirs, whereas the Kuangshan complex has experienced the fractional crystallization of hornblende in the deep and the shallow plagioclase fractional crystallization. The F, Cl and S content of the Kuangshan complex estimated by apatite volatile (F = 2632 ppm, Cl = 4100 ppm, SO3 = 140 ppm) is significantly higher than that of the Fushan complex (F = 2488 ppm, Cl = 3400 ppm, SO3 = 90 ppm). The Eu, Ce anomalies, Mn, and SO3 contents of apatite show that both of the two complexes have higher oxygen fugacity (Δ FMQ), but the oxygen fugacity of the Kuangshan complex calculated by Mn and SO3 content (Δ FMQ + 2.41) is higher than that of the Fushan complex (Δ FMQ + 1.77), which may also be one of the reasons for the great difference in ore-forming scale between the two complexes. Our results suggest that the high volatile contents and oxidation states of magma estimated by apatite, as well as the lower Sr/Y in apatite reflect favorable conditions for skarn iron mineralization. Therefore, our study shows that magmatic apatite geochemistry may be a useful tool to distinguish the Fe fertility of plutonic rocks related to skarn deposits.

The Luminescence Properties of the Interstitial Eu2+ in SrB2O4 for UV Light‐Emitting Diode

SrB2O4:Eu2+ is prepared by the high‐temperature solid‐phase method. The structure is characterized by X‐ray diffraction, and the luminescence properties are analyzed using fluorescence spectroscopy and decay curves. SrB2O4:Eu2+ has strong absorption in the UV region and two broadband emissions in the 350–550 nm, located at 374 and 458 nm. The broadband emission around 374 nm belongs to Eu2+ emission at the Sr lattice position, and the emission around 458 nm belongs to interstitial Eu2+ ions. At low concentrations, Eu2+ replaces the position of Sr2+ first, and the emission peak of 374 nm is stronger than that of 458 nm in the emission spectrum. The luminescence at 458 nm enhances significantly as the concentration of Eu2+ ions increases. The fluorescence lifetime confirms the presence of two luminescent centers, the EuSr and the interstitial Eu2+ ions. The temperature dependence luminescence of SrB2O4:Eu2+ is explored, and the activation energy is calculated to be ΔEa = 0.3622 eV. The Commission Internationale de l'Éclairage (CIE) chromaticity coordinates of SrB2O4:Eu2+ are in the blue area. The results indicate that the interstitial Eu2+ benefits the color‐rendering index when SrB2O4:Eu2+ is used as a blue phosphor in UV light‐emitting diode (LED).

Improved magnetic and dielectric quality factors with low losses in rare earth (Eu) substituted Co-Ni-Zn ferrites for high frequency devices

Co0.2Ni0.5Zn0.3EuxFe2-xO4 (CNZEFO) composites were synthesized by the conventional double sintering technique, where x = 0.00, 0.02, 0.04, and 0.08. Rietveld refined x-ray diffraction indicates the spinel cubic structure (Fd-3 m space group) of the samples. The refined XRD pattern also mentioned the Fe2O3 secondary peak for x = 0.04 and 0.08 samples. The structural lattice constant was initially increased, but after that it decreased with the Eu concentration. The bulk density of the samples was always lower than the x-ray density, where the densities were increased with the enhancement of Eu concentration. FTIR analysis confirmed the metal–oxygen bonds in ferrite with spinel cubic structure. FESEM micrographs provide the average grain size of the samples, which varies between 105.1 nm and 169.9 nm. EDX analysis was used to carry out the compositional verification and confirm that the elements were present in the required ratios. Magnetic hysteresis loop measurements were studied at room temperature, where the magnetization demonstrates the decline with the substitution of Eu ions. The addition of Eu concentration also changed other fundamental properties of the ferrites, such as coercivity (Hc), retentivity (Mr), anisotropy constant (K), and magnetic moment (nB). The permeability measurements show that the real permeability of the samples was decreasing at lower frequency region further they became high at higher frequency region. The magnetic loss tangent (tanδM) and dielectric loss tangent (tanδD) were reduced with the addition of Eu concentration, where the Eu doped samples show higher dielectric and magnetic quality factor than the pure sample. The enhancement of resistivity and impedance were also noticed for the addition of Eu content in Co0.3Ni0.2Zn0.5Fe2O4 sample. These europium doped cobalt–nickel-zinc ferrites may be strong candidates for potential high frequency applications.

Mapping of trace elements in topsoil of arid areas and assessment of ecological and human health risks in Qatar

Soil is the incubator of human activities. Mapping of soil contaminants needs to be constantly updated. It is fragile in arid regions, especially if it accompanies dramatic and successive industrial and urban activities in addition to the climate change. Contaminants affecting soil are changing due to natural and anthropogenic influences. Sources, transport and impacts of trace elements including toxic heavy metals need continuous investigations. We sampled soil in accessible sites in the State of Qatar. An inductively coupled plasma-optical emission spectrometry (ICP-OES) and an inductively coupled plasma-mass spectrometry (ICP-MS) were used to determine the concentrations of Ag, Al, As, Ba, C, Ca, Ce, Cd, Co, Cr, Cu, Dy, Er, Eu, Fe, Gd, Ho, K, La, Lu, Mg, Mn, Mo, Na, Nd, Ni, Pb, Pr, S, Se, Sm, Sr, Tb, Tm, U, V, Yb and Zn. The study also presents new maps for the spatial distribution of these elements using the World Geodetic System 1984 (projected on UTM Zone 39N) which is based on socio-economic development and land use planning. The study assessed the ecological risks and human health risks of these elements in soil. The calculations showed no ecological risks associated with the tested elements in soil. However, the contamination factor (CF) for Sr (CF > 6) in two sampling locations calls for further investigations. More important, human health risks were not detected for population living in Qatar and the results were within the acceptable range of the international standards (hazard quotient HQ < 1 and Cancer risk between 10−5 and 10−6). Soil remains a critical component with water and food nexus. In Qatar and arid regions, fresh water is absent and soil is very poor. Our findings enhance the establishment of scientific strategies for investigating soil pollution and potential risks to achieve food security.