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Lanthanides were tested (Ce3+, Er3+, and Yb3+) as catalysts to produce lactic acid (LA) from the monosaccharides present in corn stover (glucose, xylose, and arabinose) resulting in ytterbium being the most active. A MW-heated system led to similar LA yield as a conventionally heated pressurized system. The maximum value of LA yield was 40% at 240 °C after 20 min of isothermal treatment regardless the starting monosaccharides, which allowed to propose a similar LA production route based on the products profile determined along time for the three monosaccharides. Temperature and time determined the product profile, observing furfural degradation at severity factors higher than 3.5, while values higher than 5.5 were needed to observe LA degradation. By increasing temperature, catalyst solubility decreased, increasing its presence in the solid residue after treatment. Xylan conversion to LA was similar as for xylose, but lower yield was obtained from microcrystalline cellulose. Corn stover presented more amorphous regions leading to higher hydrolysis yields of its cellulose fraction. [ABSTRACT FROM AUTHOR]

Mg-based amorphous alloys have broad applications due to disordered atomic structure, thermal stability, crystallinity, low elastic modulus and high strength. In the present study, Mg–Ni–Gd–Yb–Ag alloys were prepared by vacuum arc melting combined with copper roll melt spinning. The addition of trace amounts of ytterbium (Yb) improved the corrosion resistance of Mg73-XNi15Gd10YbXAg2 (x = 2,4,6,8 at.%). Electrochemical experiments, immersion tests and analysis of corrosion products by XPS and EDS showed that Mg67Ni15Gd10Yb6Ag2 exhibited the best corrosion resistance with an Ecorr of − 968 mV and an Icorr of 5.93 µA/cm2. The superior corrosion performance was attributed to the presence of corrosion passivation films comprising MgO, Mg(OH)2, Ni(OH)2, Ag2O, AgCl, Ca5(PO4)3(OH), as well as rare-earth oxides Gd2O3 and Yb2O3. These compounds efficiently shield the matrix, and the microstructure corrosion mechanism of Mg–Ni–Gd–Yb–Ag involves a cyclic process that includes surface film layer dissolution, matrix corrosion and film layer regeneration, leading to oxide attachment. The addition of the appropriate amount of rare-earth element Yb to Mg-based amorphous alloys can improve the corrosion resistance, thereby increasing the application prospects of alloys. [ABSTRACT FROM AUTHOR]

Consideration is given to the possibility of obtaining 177Lu radionuclide on the average flux research IRT-T nuclear reactor. The paper presents the results of simulating the neutron spectrum of the central channel CEC-1 of the IRT-T research reactor in the MCU program, calculations of the production of 177Lu from 176Yb2O3 in the CEC-1 neutron field and the dose rate from different radionuclides at a distance of 1 m and experiments on the production of 177Lu and its separation. The results of calculations and experiments are in agreement within an error of no more than 10% for 177Lu. The performed calculations and experiments have made it possible to carry out a preliminary assessment of the activity of 177Lu radionuclide, which can be obtained on the IRT-T research nuclear reactor, and also determine radiation protection required for working with radioactive ytterbium and lutetium. [ABSTRACT FROM AUTHOR]

LuAG-based optical ceramics co-doped with Yb3+ and Er3+ ions was successfully synthesized for the first time. The optical, spectral-luminescent, and kinetic characteristics of ceramics based on Y2.82Yb0.15Er0.03Al5O12 (YAG 5-Yb, 1-Er) and Lu2.82Yb0.15Er0.03Al5O12 (LuAG 5-Yb, 1-Er) compositions were investigated. It is demonstrated that excitation of luminescence at a wavelength of 940 nm in YAG 5-Yb, 1-Er and LuAG 5-Yb, 1-Er ceramics results in the effective transfer of excitation radiation energy from Yb3+ ions to Er3+ ions. The energy transitions that play a pivotal role in the processes of Stokes and anti-Stokes luminescence of ceramics based on YAG 5-Yb, 1-Er and LuAG 5-Yb compositions was identified, and a schematic representation of these transitions is presented. The mutual variation of the intensity of anti-Stokes luminescence bands resulting from the transitions 2H11/2 → 4I15/2 (525 nm) and 4S3/2 →4I15/2 (546 nm) was observed, with regard to the power of the excitation radiation. This study demonstrates the potential of YAG 5-Yb, 1-Er and LuAG 5-Yb, 1-Er ceramics as materials for optical thermometry. [ABSTRACT FROM AUTHOR]

Fluorescence intensity ratio (FIR) technology is compulsorily needed in non-contact rare-earth luminescent temperature sensors. Here, we present Er/Yb:Y3Al5O12 phosphors synthesized via a high-temperature solid-state reaction method. The crystal structure, microstructure, up-conversion luminescence, and energy transfer between the two ions have been comprehensively analyzed. Under 980-nm excitation, the samples exhibited four distinct transition bands at 475 nm, 525 nm, 546 nm, and 664 nm. The quantum efficiency reached 12.14%. Utilizing the thermally coupled level of I525/I546 as a basis for analysis yields a maximum relative sensitivity of 1.05% K−1. We observed that the spectral color coordinates varied linearly with temperature within a specific range, suggesting its potential application as a means of temperature measurement. Furthermore, employing the non-thermally coupled levels of I546/I475 for temperature measurement results in an impressive maximum absolute sensitivity of 8.05% K−1, nearly 24 times higher than that achieved through thermally coupled levels alone. The temperature resolution of the synthetic material is basically less than 0.3 K with high thermal stability. Therefore, Er/Yb:Y3Al5O12 phosphors hold promise as viable candidates for components in temperature-sensor applications. [ABSTRACT FROM AUTHOR]

LuAG-based optical ceramics co-doped with Yb3+ and Er3+ ions was successfully synthesized for the first time. The optical, spectral-luminescent, and kinetic characteristics of ceramics based on Y2.82Yb0.15Er0.03Al5O12 (YAG 5-Yb, 1-Er) and Lu2.82Yb0.15Er0.03Al5O12 (LuAG 5-Yb, 1-Er) compositions were investigated. It is demonstrated that excitation of luminescence at a wavelength of 940 nm in YAG 5-Yb, 1-Er and LuAG 5-Yb, 1-Er ceramics results in the effective transfer of excitation radiation energy from Yb3+ ions to Er3+ ions. The energy transitions that play a pivotal role in the processes of Stokes and anti-Stokes luminescence of ceramics based on YAG 5-Yb, 1-Er and LuAG 5-Yb compositions was identified, and a schematic representation of these transitions is presented. The mutual variation of the intensity of anti-Stokes luminescence bands resulting from the transitions 2H11/2 → 4I15/2 (525 nm) and 4S3/2 →4I15/2 (546 nm) was observed, with regard to the power of the excitation radiation. This study demonstrates the potential of YAG 5-Yb, 1-Er and LuAG 5-Yb, 1-Er ceramics as materials for optical thermometry. [ABSTRACT FROM AUTHOR]

Thermal barrier coating (TBC) is applied to protect the hot-section components of a gas turbine engine. In the present work, a La2(Zr0.2Ti0.2Y0.2YB0.2Nb0.2)2O7 high entropy oxide was designed, fabricated by a solid-phase reaction at 1400 °C, and subjected to an investigation of its properties. The results indicate that the La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7 high entropy oxide had a pyrochlore structure. During synthesis, a small amount of La2TiO5 was produced. The thermal conductivity of the La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7 high entropy oxide was approximately 0.8855 W·m-1·K-1 at room temperature. The coefficient of thermal expansion of the La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7 high entropy oxide was approximately 9.374 × 10−6 K−1 at 1000 °C. To improve the service life of the TBC composed of the La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7, a double-layer structural coating composed of La2(Zr0.2Ti0.2Y0.2YB0.2Nb0.2)2O7 and yttria-stabilized zirconia (YSZ) layers was designed and produced on a NiCoCrAlY alloy by laser cladding. The thermal cycling behavior of the double-layer coating was studied at 1050 °C. The results indicate that a La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7 single-phase defective-fluorite high entropy oxide was produced after preparation and thermal cycling. The spallation of the double-layer coating composed of La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7/YSZ occurred after 70 thermal cycles at 1050 °C. The double-layer coating composed of La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7/YSZ can increase the thermal cycling lifetime of TBCs containing high entropy oxides. [ABSTRACT FROM AUTHOR]

In this paper, a Wide tunble in C + L band single-wavelength passively Q-switched fiber laser (PQFL) consisting of cascaded doped fiber segments and a tunable band-pass filter (TBF) is proposed. The TBF achieves precise tuning of the wavelength with a maximum tunable range of 45.04 nm (1529.08–1574.12 nm). When the fiber is non-completely pumped, erbium-doped fiber (EDF) and erbium-ytterbium co-doped fiber (EYDF) act as saturable absorbers (SA). It has different nonlinearities under different pump power combinations, producing passively Q-switched pulses with repetition frequencies from 8.23 kHz to 46.47 kHz and pulse widths reduced from 12.82 μs to 2.00 μs. In addition, the wavelength range of passively Q-switched is also changing from 11.55 nm to 31.04 nm. In the experiment, the change in the wavelength range of the passively Q-switched pulse was explained by analyzing the gain saturation absorption characteristics of the EDF and the EYDF. In the experiment, only four devices are used to achieve single-wavelength wide tuning and passively Q-switched, which is enough to prove the simplicity and compactness of the structure. The proposed FQFL has broad application prospects in the fields of distributed sensing systems and bio-medical imaging. [ABSTRACT FROM AUTHOR]

BaGeTeO6: Nd3+/Yb3+/Ho3+ green up-conversion phosphors were synthesized using the high-temperature solid-state reaction method. The optimal doping concentrations for the three dopant ions Nd3+, Yb3+, and Ho3+ were determined to be 1 mol%, 6 mol%, and 0.8 mol%, respectively, through the method of controlling variables. By analyzing the dependence of the up-conversion luminescence intensity on the pump current of the 980 nm laser, it was found that the green and red up-conversion emissions of Ho3+ ions under 980 nm laser excitation were both two-photon processes. Furthermore, the influence of temperature on the up-conversion luminescent properties of BaGeTeO6: Nd3+/Yb3+/Ho3+ green up-conversion phosphors under 980 nm laser excitation was investigated, and the temperature sensing properties of Ho3+ ions were discussed. The results indicated that, at room temperature and higher temperatures, both the red and green up-conversion emissions of the sample were two-photon processes. Within the range of excitation current used in the experiment, the ratio of red to green up-conversion luminescence intensity of Ho3+ ions was independent of the laser excitation current but correlated with the sample temperature. In the temperature range of 303–723 K, the ratio of red to green up-conversion luminescence intensity of Ho3+ ions exhibited a nonlinear relationship with temperature. Comparing the temperature sensing sensitivity of Ho3+ in different matrices, the results indicated that the sample possessed high temperature sensing sensitivity. [ABSTRACT FROM AUTHOR]

Bulk samples of holmium and ytterbium rare earth titanates doped with yttrium and bismuth were synthesized. To study the magnetic properties and peculiarities of magnetic interaction in doped and undoped titanates, magnetization curves and temperature dependences of the susceptibility were measured in fields up to 3 T at temperatures from 2 to 300 K. Magnetic properties for doped and undoped titanates with different doping level, as well as doped with different elements, have been compared. Based on study of temperature dependences of the susceptibility, magnetic dipole and exchange interactions have been analyzed. In the case of undoped holmium titanate, the dominant magnetic interaction type has been found to be the dipole one. When doping of holmium titanate with yttrium and bismuth, the magnetic interactions between the rare earth ions are sharply weak. Undoped ytterbium titanates have shown a predominance of the superexchange interaction. Presence of a large number of randomly distributed yttrium or bismuth ions, which occupy positions of ytterbium ions in crystal lattice, leads to the decrease in concentration of R3+-O-R3+ ion pairs in this rare earth titanate, between which there is superexchange. Therefore, in doped compounds, the magnetic dipole interaction capable to act at large distances contrary to the superexchange one begins to predominate. The values of the g-factor have been estimated by the fit of the measured magnetization curves. [ABSTRACT FROM AUTHOR]

To ensure the safety of medical personnel in healthcare organizations, radiation-shielding materials like protective clothing are used to protect against low-dose radiation, such as scattered rays. The extremities, particularly the hands, are the most exposed to radiation. New materials that can be directly coated onto the skin would be more cost-effective, efficient, and convenient than gloves. We developed protective creams using eco-friendly shielding materials, including barium sulfate, bismuth oxide, and ytterbium oxide, to avoid harmful effects of heavy metals like lead, and tested their skin-protective effects. Particularly, the radiation-shielding effect of ytterbium oxide was compared with that of the other materials. As shielding material dispersion and layer thickness greatly affect the efficacy of radiation-shielding creams, we assessed dispersion in terms of the weight percentage (wt%). The effective radiation energy was reduced by 20% with a 1.0-mm increase in cream thickness. Ytterbium oxide had a higher radiation-shielding rate than the other two materials. A 28% difference in protective effect was observed with varying wt%, and the 45 wt% cream at 63.4 keV radiation achieved a 61.3% reduction rate. Higher content led to a more stable incident energy-reducing effect. In conclusion, ytterbium oxide shows potential as a radiation-shielding material for creams. [ABSTRACT FROM AUTHOR]

A series of MnFe2–xYbxO4 powder nanoparticles (for x = 0, 0.025, 0.075, 0.1, and 0.2) of different crystallite sizes were synthesised using the co-precipitation method. The effect of Yb3+ dopant on the properties of manganese ferrite was characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman measurements, and photoluminescence spectroscopy (PL). The crystallite size and density of the samples have a cubic structure with an Fd3m space group. Their sizes and densities were found to be in the range of 24.8–34.7 nm and 5.07–5.49 g/cm3. FT-IR analysis indicates the presence of two absorption bands in the range 400–600 cm–1, which is a fingerprint region of ferrites. The v2 band (Fe–O stretching mode of the octahedral site) shifts towards the lower wavenumber, which confirms the occupancy of larger-size Yb3+ ions at the octahedral site. The Raman peaks were noted at 228, 295, 405, 502, and 634 cm–1 for undoped manganese ferrite. Based on Raman observations, it has been observed that Mn2+ ions exhibit a preference for occupying octahedral (B) sites by substituting Fe3+ ions. Additionally, rare earth ions have been preferentially observed to occupy octahedral sites. The primary cause for the displacement of Raman bands was ascribed predominantly to the greater radii of rare earth ions in comparison with Fe3+ and Mn2+ ions, and the shifting of the peaks indicates the presence of Yb3+ at the octahedral site. The PL spectrum shows emission at 560 nm with a rise in intensity with an increase in dopant Yb3+, which could be because of the incorporation of Yb3+ in the spinel structure, leading to radiative recombination in the yellow region of the electromagnetic spectrum. [ABSTRACT FROM AUTHOR]

Using a solid-state technique under low temperature conditions, Er3+/Yb3+ co-doped Bi2Mo2O9 phosphors with different concentrations were prepared, exhibiting excellent green up-conversion luminescence property. A thorough investigation was conducted on the phase structure, optical transition, up-conversion luminescence, and down-shifting luminescence properties of the prepared samples. Bi2Mo2O9: Er3+/Yb3+ phosphors excited at 381, 980, and 1550 nm showed strong green fluorescence together with very faint red emission. The mechanism of up-conversion luminescence and its capacity for temperature sensing were examined under the excitation of various wavelengths. Under 980 nm excitation, the maximal relative and absolute sensitivities were determined to be 1.107%K− 1 and 0.756%K− 1 at 303 K and 513 K, respectively. Furthermore, the Judd-Ofelt intensity parameters of Er3+ in Bi2Mo2O9: Er3+/Yb3+ phosphors were calculated using the diffuse reflectance spectra and fluorescence lifetime of Er3+. In addition, material was combined with polyacrylic acid to make an anti-counterfeiting pattern. The results indicate that Bi2Mo2O9: Er3+/Yb3+ phosphor is an excellent green phosphor with optical temperature measurement function, and it also has certain applications in the field of anti-counterfeiting. [ABSTRACT FROM AUTHOR]

We present new aspects of erbium- or ytterbium-doped pure gadolinium oxide (Gd2O3:Er3+/Yb3+) as a suitable candidate for drug delivery and magnetic resonance (MR) applications. The samples were prepared using the conventional sol–gel synthesis technique. The structural studies revealed that the prepared sample was monophased and crystallizes in a cubic structure. FTIR measurements confirmed the creation of Gd2O3:Er3+/Yb3+ phosphor. SEM micrographs clearly indicated that the particles crystallized in uniform shape, exhibiting nano-rod formation, with the particle size ranging from 55 to 5 nm. TEM images revealed that Er3+- and Yb3+-co-doped Gd2O3 nanoparticles were the collection of the nano-rods 2–4 nm thick and 18–20 nm long. Also, photoluminescence analysis of the phosphor samples for variable concentrations of doping ions was presented. When doped with Er3+/Yb3+, nano-rod Gd2O3 emits intense green emission and some red emission peaks, under a 980-nm near-infrared laser. Our study shows that as-prepared samples may be useful for optical imaging systems and that nano-rod formation may be used as a major host carrier for drug delivery. [ABSTRACT FROM AUTHOR]

Tri-doped phosphor YNbO4:Er3+/Tm3+/Yb3+ was prepared by solid-state reaction method. The XRD and SEM results reveal that the product is a monoclinic phase of YNbO4 with high crystallinity and the particles presenting grains with well-defined boundaries with average size is about 1–5 μm. The temperature-dependent luminescence is investigated with 980 nm laser excitation, whereas temperature sensing behaviour was studied in the range of 300–500 K based on Stark sublevels 1G4(a)/1G4(b) (Tm3+), thermal coupling levels 2H11/2/4S3/2 (Er3+) and non-thermal coupling levels 4F9/2 → 4I15/2 (Er3+) /3F2 → 3H6 (Tm3+), 2H11/2 → 4I15/2 (Er3+) / 4F9/2 → 4I15/2 (Tm3+) and 4S3/2 → 4I15/2 (Er3+) /3F2 → 3H6 (Tm3+), utilizing fluorescence intensity ratio (FIR) technique. It is worth highlighting that 1G4(a)/1G4(b) ratio as is not much employed in thermometry. Regarding, NTCL 3F2/1G4(b) pair exhibited the highest absolute sensitivity (SA) is about 110.2 × 10− 3 K− 1 at 500 K, whereas NTCL 3F2/4F9/2 pair presented the highest relative sensitivity (SR) is 2.1% K− 1 at 339 K. Meanwhile, the temperature-dependent emission colours are discussed in detail. High sensitivity indicates that YNbO4:Er3+/Tm3+/Yb3+ white-light phosphor can be used in non-contact temperature sensors applications. [ABSTRACT FROM AUTHOR]

Barium titanium borate glasses doped with ytterbium with the chemical composition of B2O3-TiO2-BaO-Yb2O3 are described as shields exhibiting excellent performance for β and γ applications. This study used the Phy-X and XCOM codes and the GEANT4 toolkit to calculate and simulate the gamma attenuation factors in a 0.02-MeV to 15-MeV range. From the linear attenuation coefficient and mass attenuation coefficient (MAC) values, the half-value layer (HVL), tenth value layer, mean free path (MFP), effective atomic number (Zeff), electronic cross-section, and atomic cross-section have been determined. In addition, the energy absorption build-up factors and exposure build-up factors values of glass samples were estimated for the energy spectrum spans from 0.02 MeV to 15 MeV and penetration depths up to 40 MFP. Additionally, we analyzed the heaviness (H%) of the selected samples, utilizing this crucial metric as a fundamental parameter to comprehend the distinctive properties of diverse materials. Furthermore, we determined the radiation protection efficiency (RPE), and observed that it is prominent at lower energies, gradually decreasing as the energy level rises. Incorporating Yb3O2 resulted in an augmentation of the RPE values, thereby enhancing the shielding capabilities of the glass system. The ESTAR program assessed the β-shielding action of the inspected glasses by determining the total stopping power (TSP) and the continuous slowing down approximation (CSDA) range. The findings indicate that the incorporation of ytterbium positively impacts the density, consequently enhancing the shielding proficiency, of the sample against β- and γ-rays. In BTBaY4 glass, the variant with the greatest concentration of Yb2O3 exhibits the greatest values for MAC, Zeff, and the most minimal HVL. Moreover, this type of glass has low concentrations of Yb2O3 and is free from lead materials, but shows good shielding properties. [ABSTRACT FROM AUTHOR]

Experiments have been carried out to study the transient radiation-induced absorption in the active core of a double-clad ytterbium fiber and the response of a laser based on it under the exposure of pulsed X-rays. It has been found that the time of loss of laser performance (downtime) under pulsed irradiation increases with an increase in the absorbed of radiation and a decrease in the laser pump power and reaches values of ∼1 ms. An analysis of the experimental results shows that the laser response to the X-rays pulse exposure is determined by radiation-induced losses in the active fiber core. An experimental-calculated method for estimating the radiation reaction of a laser, based on the results of studies of the active fiber, is proposed. [ABSTRACT FROM AUTHOR]

We report on the characterization and first laser operation of ceramic Yb:LuScO3 in a thin-disk oscillator. The optical performance achieved with a ceramic Yb:LuScO3 disk is compared to the one obtained with an existing ceramic Yb:Lu2O3 disk for reference. The characterization covers the measurement of the fluorescence spectra, the fluorescence lifetimes, and nomarsky imaging. The investigation on the laser operation covers the measurement of resonator losses, output powers, and thermal behavior during continuous-wave operation in a multimode thin-disk oscillator. An average output power of 149 W and a slope efficiency of 51.8% were achieved with the ceramic Yb:LuScO3 disk which reached a maximum surface temperature of about 150 °C. At the same temperature level, a disk made of the already established ceramic Yb:Lu2O3 delivered 957 W of output power with a slope efficiency of 75.7%. [ABSTRACT FROM AUTHOR]

The modern turbines aimed to work at enhanced efficiencies demand the use of a novel high-performance thermal barrier coating (TBC) which may be susceptible to multiple failure modes. Specifically, ingestion of calcium–magnesium–alumino–silicate (CMAS) or volcanic ash (VA) at elevated temperatures induce accelerated deterioration of conventional yttria-stabilized zirconia (YSZ) TBCs. The ability to form an impervious and rapidly crystallizing rare earth-based apatite layer upon interaction with CMAS/VA salt favors the choice of rare earth zirconates (REZs) as novel TBCs. Among diverse REZs, Yb2Zr2O7 (YbZ) exhibits ideal TBC characteristics. A detailed insight into YbZ coating characteristics and performance is vitally needed to qualify these materials for TBC applications. Accordingly, in this study indigenously developed YbZ and commercial YSZ were deposited by air plasma spraying. Subsequently, the VA infiltration resistance of deposited coatings was comprehensively compared up to 1350 °C. The SEM analysis of VA-infiltrated YSZ and YbZ coatings revealed the thickness of the infiltration zone and the corresponding mechanism. YbZ coatings displayed significantly better VA infiltration resistance attributed to forming an impervious Yb-apatite-based arresting layer and pinning the further seepage of the VA salt front. Besides, VA rapidly infiltrated YSZ coatings, which failed to form an arresting layer. Overall, the study provides essential insights and thrust in developing next-generation TBCs. [ABSTRACT FROM AUTHOR]

Runoff of terrigenous material involved in the structure of Neogene rare metal–Ti placers of the northeastern side of the Dniepr–Donets Basin (DDB) is determined using lithological and mineralogical methods including U–Pb geochronological and chemical study of detrital zircon. The peculiarities of an assemblage of accessory minerals of heavy fraction of placers, the morphology of individual grains, and the depletion of most zircons in U, Th, Y, and Yb indicate that the material was sourced from chemical weathering mantles, which probably developed after Proterozoic (70%) and Neoarchean (15%) metamorphic rocks. The presence of Paleozoic zircon crystals and a higher U, Th, Y, and Yb content are evidence of the erosion of igneous rocks of the Neoproterozoic–Early Paleozoic trap complexes and Devonian intrusive and volcanosedimentary rocks of the DDB. The involvement of clasts of the above rocks in sedimentary recycling was promoted by the evolution of abundant DDB salt tectonics. [ABSTRACT FROM AUTHOR]

The Tirodi Gneissic Complex (TGC) represents the basement sequence of the Central Indian Tectonic Zone (CITZ), underlying the Proterozoic supracrustal sequences of the Sausar and Betul Groups of rocks. Lithologically, the TGC constitutes a combination of pink and grey granitic gneiss assemblages, characterised by biotite-rich, hornblende-biotite-rich, and muscovite-biotite-rich granite gneiss. Compositionally, the TGC granitoids represent tonalite-trondhjemite-granodiorite to granite, and have calc-alkaline lineage with metaluminous to peraluminous characteristics. Geochemically, they dominantly belong to A2-type granitoids. Chondrite normalised REE ratios of La/Sm, La/Yb, La/Gd, and Gd/Yb indicate diverse LREE/HREE enrichment. Multi-element patterns for the TGC granitoids are characterised by light rare earth elements (LREE) and large ion lithophile elements (LILE) enrichment and depletion of high field strength elements (HFSE: Nb, P, and Ti) and strong positive Pb and Th anomalies. The observed negative anomalies for HFSE are attributed to diverse crustal/lithospheric sources, with some influence from K-feldspar, plagioclase and Ti-oxide fractionation. Sm–Nd data presents initial 143Nd/144Nd (t = 1.7 Ga) ratios (0.509898 to 0.510508), and εNd (t = 1.7 Ga) is (+ 0.58 to -10.59), with TDM model ages ranging from 2.11 to 2.95 Ga. Such a wide range of εNd (t = 1.7 Ga), indicates heterogeneous crustal/lithosphere sources, which have probably experienced longer crustal residence times. Zircon U–Pb ages for individual TGC samples are 1506 ± 11 Ma (TG-01), 1534 ± 26 Ma (MU-5), 1675 ± 9 Ma (BT-4), 1724 ± 11 Ma (BT-3), 1730 ± 13 Ma (BT-4), and 1960 ± 2 Ga (Ms-2), respectively. These ages have probably recorded the key periods of the Columbia supercontinent's assembly, growth, and breakup. Geochemical and geochronological results suggest that the TGC granitoids have a crustal/lithospheric origin and are formed by partial melting of felsic sources in dominantly VAG (volcanic arc granite) and, to some extents, WPG (within-plate granite) settings. [ABSTRACT FROM AUTHOR]

A series of BiTa7O19(BTO):Ho3+/Yb3+ phosphors were prepared by high-temperature solid state sintering, which exhibited outstanding pure green upconversion luminescence (UCL) under 980 nm laser excitation. When Ho3+ doping 10 mol%, Yb3+ has almost no concentration quenching point. By optimizing the preparation process, the phase purity of the sample can be improved. Under 980 nm laser excitation power density of 124.99 W/cm2, the UCL intensity of the optimized sample is 1.79 times that of the non-optimized sample. The maximum relative temperature sensitivity SR of 0.384% K−1 at 557 K and 0.40% K−1 at 723 K can be obtained by using luminescence intensity ratio (LIR) technique. All experiments show that BTO is an excellent UCL host, and BTO:Ho3+/Yb3+ can be used in UCL display and temperature sensing. [ABSTRACT FROM AUTHOR]

Gold nanoclusters are a smart platform for sensing potassium ions (K+). They have been synthesized using bovine serum albumin (BSA) and valinomycin (Val) to protect and cap the nanoclusters. The nanoclusters (Val-AuNCs) produced have a red emission at 616 nm under excitation with 470 nm. In the presence of K+, the valinomycin polar groups switch to the molecule's interior by complexing with K+, forming a bracelet structure, and being surrounded by the hydrophobic exterior conformation. This structure allows a proposed fluorometric method for detecting K+ by switching between the Val-AuNCs' hydrophilicity and hydrophobicity, which induces the aggregation of gold nanoclusters. As a result, significant quenching is seen in fluorescence after adding K+. The quenching in fluorescence in the presence of K+ is attributed to the aggregation mechanism. This sensing technique provides a highly precise and selective sensing method for K+ in the range 0.78 to 8 µM with LOD equal to 233 nM. The selectivity of Val-AuNCs toward K+ ions was investigated compared to other ions. Furthermore, the Val-AuNCs have novel possibilities as favorable sensor candidates for various imaging applications. Our detection technique was validated by determining K+ ions in postmortem vitreous humor samples, which yielded promising results. [ABSTRACT FROM AUTHOR]

The reaction of the complex [(dpp-bian)2−Yb2+(THF)4] (dpp-bian is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with two molar equivalents of 1,3-bis(pyridin-4-yl)propane (bpp) in tetrahydrofuran (THF) afforded the 2D coordination polymer [{(dpp-bian)Yb(bpp)2} • 3 THF]n (1). The reaction of [(dpp-bian)2−Yb2+(DME)2] with phenazine (phz) gave the dimeric complex [{(dpp-bian)Yb(DME)}2(μ-η3:η3-phz)] • 2 DME (2), in which two cationic {(dpp-bian)Yb(DME)} units are connected via a bridging phenazine dianion. Compounds 1 and 2 were characterized by elemental analysis and IR spectroscopy. Their molecular structures were determined by single-crystal X-ray diffraction analysis. Thermal stability of compound 1 was studied by thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

We report on the characterization and first laser operation of ceramic Yb:LuScO3 in a thin-disk oscillator. The optical performance achieved with a ceramic Yb:LuScO3 disk is compared to the one obtained with an existing ceramic Yb:Lu2O3 disk for reference. The characterization covers the measurement of the fluorescence spectra, the fluorescence lifetimes, and nomarsky imaging. The investigation on the laser operation covers the measurement of resonator losses, output powers, and thermal behavior during continuous-wave operation in a multimode thin-disk oscillator. An average output power of 149 W and a slope efficiency of 51.8% were achieved with the ceramic Yb:LuScO3 disk which reached a maximum surface temperature of about 150 °C. At the same temperature level, a disk made of the already established ceramic Yb:Lu2O3 delivered 957 W of output power with a slope efficiency of 75.7%. [ABSTRACT FROM AUTHOR]

Due to the BCS theory, hydrogen, the lightest element, would be the prospect of room-temperature superconductor after metallization, but because of the difficulty of the hydrogen metallization, the theory about hydrogen pre-compression was proposed that the hydrogen-rich compounds could be a great option for the high Tc superconductors. The superior properties of TmH6, YbH6 and LuH6 indicated the magnificent potential of heavy rare earth elements for low-pressure stability. Here, we designed XTmH12 (X = Y, Yb, Lu, and La) to obtain higher Tc while maintaining low pressure stability. Most prominently, YbTmH12 can stabilize at a pressure of 60 GPa. Compared with binary TmH6 hydride, its Tc was increased to 48 K. The results provide an effective method for the rational design of moderate pressure stabilized hydride superconductors. [ABSTRACT FROM AUTHOR]

As part of the development of critical technologies, it is necessary to search for alternative replacement of components in the compositions of aluminum ligatures, including known modifying additives of scandium and yttrium with other rare-earth and rare elements. Aluminum ligatures with rare-earth metals are widely considered in many scientific papers, but the research on the production of Al-Yb ligatures is limited. In this paper, the authors describe the results of studying the production of ligatures of the aluminum-ytterbium system from ytterbium oxide by aluminothermic reduction, containing nanoscale Al3Yb intermetallic compounds and eutectics in their structure. Serving as crystallization centers, the optimal-size particles of intermetallic compounds provide uniform fine-grained structure in aluminum alloy castings. The relationship has been obtained that enables the maximum transition of ytterbium into the alloy depending on the quantitative and qualitative composition of the reaction mixture and various melting process parameters. The conducted studies have shown that ligatures obtained by aluminothermic reduction of ytterbium oxide with the addition of 5 to 15 wt. % Mg to the reaction mixture have the highest characteristic of ytterbium transition into the ligature. [ABSTRACT FROM AUTHOR]

A new phosphor Sr5(BO3)3Cl:Ce3+,Yb3+, which enables near-infrared (NIR) quantum cutting, was prepared using traditional solid-state reaction methods. Its properties were examined using X-ray diffraction, photoluminescence emission, excitation spectra, and measurements of fluorescence decay. Upon excitation of Ce3+ with an ultraviolent (UV) photon at 350 nm, broadband emission at 415 nm and an intense NIR emission at 982 nm were observed. Emission at 415 nm corresponds to 5d→4f transition of Ce3+ ions, whereas the NIR emission at 982 nm is ascribed to the characteristic 2F5/2 → 2F7/2 transition of Yb3+ ions. Thorough investigation delved into how the concentration of Ce3+ affects visible and NIR emissions, decay lifetime, and energy transfer efficiency (ηETE). Detailed analysis of photoluminescence excitation, emission spectra, and fluorescence decay measurements revealed a proficient energy transfer from Ce3+ to Yb3+ ions. This transfer was demonstrated as a cooperative energy transfer (CET) process, showcasing a CET efficiency of 71.2% and a total theoretical quantum efficiency of 171.2%. [ABSTRACT FROM AUTHOR]

The complete computational model of a low-mode ytterbium-erbium doped fiber amplifier, based on the numerical analysis of rate equations, was developed. In contrast to existing models, we considered the effects of the secondary energy transfer and the upconversion as well as the presence of isolated ytterbium ions and clustered erbium ions in the aggregate. In addition, the presence of several transverse modes and the effect of transverse spatial hole burning were took into account, too. Necessary parameters of the active medium were determined experimentally by measuring the luminescence decay of active ions and the output power and optical spectrum of a fiber amplifier. The proposed model allows one to calculate both the power and spectral characteristics of ytterbium-erbium doped fiber amplifiers, and the nonstationary dynamics of the population inversion and the luminescence of active ions. This can help one to select the required concentrations of active ions, the geometry and the length of active fibers for each specific task. [ABSTRACT FROM AUTHOR]

In this paper, undoped BaBi2−x−yNb2ErxYbyO9 (BBN), Er3+ doped BBN, and a series of Er3+/Yb3+ co-doped BBN ferroelectric ceramic is synthesized by the solid-state method to study the structural, dielectric, ferroelectric, and energy storage behavior of the prepared ceramic. XRD spectra revealed orthorhombic geometry and Fmmm phase group of each prepared ceramic. SEM micrograph shows dense microstructures similar to square-shaped structures. Two FTIR bands at 619 and 822 cm−1 are observed, displaying the characteristic peaks of the Aurivillius phase. Four Raman bands are detected for undoped BBN, while twelve are visible in Er3+/Yb3+ doped BBN compositions. Further, this work utilizes a comparable method to correlate Nb–O stretching frequencies with their corresponding bond lengths using Herschbach's exponential function. Temperature-dependent dielectric studies show considerable dispersion below and above maximum temperature (Tm), and the dielectric constant (εʹ) decreases with an increase in frequency. The dielectric loss (ɛʺ) curves are quite diffused, and shifts in the maxima with frequency have been observed, thus validating the relaxor behavior of all the prepared BBN compositions. The slimmer PE curves were obtained under moderate electric fields ranging from 75 to 100 kV/cm. The energy storage parameters (W, Wrec, η) are improved with increasing applied electric field. The energy storage efficiency (η) obtained for undoped, Er3+ doped, and Er3+/Yb3+ co-doped BBN ceramics are 78.25%, 83.39%, and 90.87%, respectively. The energy storage parameters revealed good temperature stability from 303 to 415 K, indicating that the synthesized material might aid in developing modern electronic equipment for energy storage applications. [ABSTRACT FROM AUTHOR]

Visible and near-infrared (NIR) upconversion luminescence (UCL) emissions originating from the BaY2F8: Yb3+, Tm3+ systems were investigated under a laser excitation at 980 nm. The BaY2F8:20 mol% Yb3+, x mol% Tm3+ and BaY2F8: y mol% Yb3+, 0.5 mol% Tm3+ phosphors showed prominent UCL at 800 and 810 nm. The optimized doping concentrations of Yb3+ and Tm3+ in the BaY2F8 host matrix were evaluated, their spectroscopic properties were determined, and studies on their temperature-dependent behaviour were carried out. The temperature-sensing properties were studied by generating the fluorescence intensity ratio (FIR) of the UCL peaks originating from the thermally-coupled energy levels of the Tm3+ ions. The Stark sublevels of 1G4 level of Tm3+ ions were utilized to estimate the temperature-sensing abilities of the phosphor. [ABSTRACT FROM AUTHOR]

Upconversion (UC) nanomaterials are of interest to researchers because of their excellent photostability, effective quantum efficiency and optical temperature dependence. However, most UC nanomaterials are thermally quenched, which causes optical nanothermometers to be susceptible to their own thermal effects, reducing the accuracy of temperature measurements. In this paper, NaYF4:Yb3+/Ho3+/Tm3+/Gd3+ nanorods with UC luminescence and resistance to thermal quenching are prepared through a simple hydrothermal method. The UC luminescence intensity of NaYF4:Yb3+/Ho3+/Tm3+/Gd3+ nanorods is adjusted by doping with Tm3+ ions. The luminescence intensity at each location shows different temperature dependence as the temperature increases. When the temperature reaches 573 K, the integrated luminescence intensity is three times that at 293 K. At the same time, the intensity at all temperature points in the range of 293–573 K is greater than the intensity at 293 K, which shows that the nanorods have excellent resistance to thermal quenching. In addition, the relative sensitivity (Sr) of LIR(I696/I476), LIR(I696/I541), LIR(I696/I646), LIR(I696/I802), and LIR(I541/I476) is investigated based on the luminescence intensity ratio (LIR) technique. The Sr of LIR(I696/I802) is found to have larger values in the low-temperature range, while Sr of LIR(I696/I476) has larger values in the high-temperature range. The use of LIR(I696/I802) and LIR(I696/I476) in separate temperature bands allows Sr to reach 0.93–1.67 %K−1 in the range of 293–573 K, confirming that the nanorods have high Sr over a wide temperature interval. This study indicates that the NaYF4:Yb3+/Ho3+/Tm3+/Gd3+ nanorods are promising candidates for optical thermometers with high sensitivity, wide temperature range, and resistance to thermal quenching. [ABSTRACT FROM AUTHOR]

New data on phase states and structural phase transitions in alloys Fe73Ga27 doped with Dy, Er, Tb, and Yb in an amount of about 0.5 at % are presented. Structural data were obtained in neutron diffraction experiments performed with high resolution and in continuous temperature scanning mode during heating to 850°C and subsequent cooling at a rate of ±2°C/min. It has been established that both the sequence of forming and disappearing structural phases and the final state of the alloy depend on the type of rare earth element. Phase transitions in the alloy with Dy are similar to those in the initial Fe73Ga27 alloy, excluding the final state. The procedure of doping with Er and Tb leads to the formation of disordered A1 and A3 phases instead of the L12 and D019 ordered close packed phases, respectively. In the case of doping with Yb, neither of the above phases is observed. The formation of the L60 (m-D03) and D022 tetragonal structural phases previously discovered in similar alloys by the electron diffraction method is not confirmed. [ABSTRACT FROM AUTHOR]

Luminescence quench is common in overdoped upconversion nanoparticles. Various methods have been proposed to counteract the adverse effects of concentration quenching on luminescence, but in upconversion nanoparticles that are highly doped with both sensitizers and activators, the factors that contribute to the diminishing of the emission cannot be summarized by a single cause. Herein, a core-shell design is used to spatially separate the sensitizer (Yb3+) and activator (Er3+) and to modulate the emission by changes in the distribution position as well as the concentration of the dopant ions in order to probe the factors affecting the luminescence. When the sensitizer ions are located in the core, the luminescence intensity of the nanoparticles is significantly weaker than that of the other distribution, which implies that the effect of sensitizer and activator on luminescence in the highly doped state has a different and more complex mechanism. The intensity of the emission is more affected by Yb3+ than Er3+, which includes not only the self-quenching of Yb3+, but also the dominance in the Yb3+–Er3+ cross-relaxation. In this finding may provide new ideas for revealing the reasons for the diminished luminescence of highly doped upconversion nanoparticles and thus for enhancing luminescence. [ABSTRACT FROM AUTHOR]

Here, this study reports single-band red upconversion emission in β-Ba2ScAlO5: Yb3+/Er3+ phosphor by doping Mn2+. The optimum concentration of Mn2+ ions in β-Ba2ScAlO5: Yb3+/Er3+ phosphor was 0.20. The intensity of red and green emissions is increased by 27.4 and 19.3 times, respectively. Compared with the samples without Mn2+ ions, the red-green integral strength ratio of β-Ba2ScAlO5: Yb3+/Er3+/Mn2+ sample was significantly increased by 28.4 times, reaching 110.9. The UCL mechanism was explored by analyzing the down-conversion luminescence spectra, absorption spectra, UCL spectra, and upconversion fluorescence lifetime decay curves of Yb3+/Er3+/Mn2+ co-doped β-Ba2ScAlO5. The enhancement of upconversion red light is achieved through energy transfer between defect bands and Er3+ ions, as well as energy transfer between Mn2+ ions and Er3+ ions. In addition, the Mn2+ doped β-Ba2ScAlO5: Yb3+/Er3+ red UCL phosphors have great potential for ambient temperature sensing in the 298–523 K temperature range. The maximum sensitivity of β-Ba2ScAlO5: Yb3+/Er3+/Mn2+ phosphor as a temperature sensor at 523 K is 0.0247 K−1. [ABSTRACT FROM AUTHOR]

The congruent melting compositions in the MF2–M'F2–RF3 systems (M ≠ M' = Ca, Sr, Cd, Ba, Pb; R are rare-earth elements (REEs)) have been determined based on thermodynamic topological analysis. Crystals of fluorite solid solution in the PbF2–CdF2–RF3 (R = Tb, Ho, Er, Tm, Yb, Lu) systems were grown by the vertical directional crystallization technique. Their phase composition and distribution of components over the crystalline boule length were investigated. Crystals of congruently melting solid solutions (Pb0.67Cd0.33) RxF (R = Tb, Ho, Er, Tm, Yb, Lu) were grown for the first time. Traces of low-temperature transformation—a phase isostructural to the Pb2YF7 compound (sp. gr. I4/m), in which Y sites are occupied by the corresponding R cations and Pb sites can be partially occupied by Cd cations—were found in the crystals with R = Ho, Er, Tm, and Yb. The crystals with R = Tb and Lu have a high degree of homogeneity and are suitable for optical studies. [ABSTRACT FROM AUTHOR]

LiRF4 (R = Y, Yb, Lu) nanoparticles (NPs), co-doped by Yb3+/Er3+ and Yb3+/Tm3+ ions, have been synthesized by high-temperature coprecipitation method. The influence of the molar ratio of precursors and the cation composition of matrices on the sizes and morphology of particles is investigated. The method of heterogeneous crystallization of these compounds using LiYF4 nanoseeds is optimized, which opens opportunities to controlled synthesis of LiRF4 NPs with required characteristics. Among the objects studied, LiYF4@LiYbF4:Tm3+@LiYF4 NPs demonstrate the most intense anti-Stokes photoluminescence in the UV (λ = 362 nm) and blue (λ = 450 nm) ranges, which exceeds the corresponding characteristics for β-NaYF4:Yb3+/Tm3+@NaYF4 particles. LiYF4@LiLuF4:Yb3+/Er3+@LiYF4 NPs are the most efficient IR converters in the (λ = 1530 nm) among the investigated isostructural matrices; their spectral-luminescence characteristics are close to those of the β-NaYF4:Yb3+/Er3+@NaYF4 compound with the equivalent degree of codoping. The results obtained give possibilities to consider LiYF4@LiYbF4:Tm3+@LiYF4 and LiYF4@LiLuF4:Yb3+/Er3+@LiYF4 NPs as a real alternative to the most widely used phosphors based on hexa-gonal β-NaYF4 host for photonics and biotechnology applications. [ABSTRACT FROM AUTHOR]

This study details the successful creation of a nanocomposite consisting of reduced graphene oxide (rGO) and Yb2O3 using a hydrothermal-assisted simple solution method. The research underscores the significance of this rGO: Yb2O3 composite material, which has emerged as a focal point of interest. The comprehensive analysis of the composite's structural features, as revealed by various techniques, offers vital insights into its distinctive properties. These insights hold profound implications for potential applications, especially in the field of advanced materials. The structural characterization techniques not only enhance our understanding of the composite's crystal structure, molecular vibrations, elemental composition, and surface chemistry but also highlight its potential as a superior material for various scientific and technological endeavors. Furthermore, this study emphasizes the importance of research and development efforts dedicated to rGO: Yb2O3 composite materials, particularly in the context of supercapacitor applications. Morphological examinations confirm the uniform distribution of Yb2O3 nanoparticles on both sides of the rGO sheets, with sizes below 50 nm. Notably, the nanocomposite exhibits significantly enhanced specific capacitance (1382.72 Fg−1 at 5 mVs−1) compared to pristine Yb2O3 nanoparticles (753.27 Fg−1 at 5 mVs−1). This improvement can be attributed to the synergistic interaction between rGO and Yb2O3, which enhances the charge storage capacity. Electrochemical characterization reveals dominant pseudo-capacitance behavior typical of batteries, making the nanocomposite a promising candidate for energy storage applications. In summary, this study illuminates the potential of graphene-based nanocomposites as high-performance energy storage materials and offers valuable insights for future research endeavors, including optimizing synthesis parameters and evaluating long-term stability. The rGO: Yb2O3 nanocomposite exhibits tremendous promise for advanced energy storage systems. [ABSTRACT FROM AUTHOR]

The work investigated the sorption of no-carrier-added 177Lu isolated from neutron-irradiated 176Yb2O3, and carrier-added 177Lu obtained by irradiation of natLu2O3, by commercial and oxidized nanodiamonds (NDs) of various grades from aqueous solutions to identify among them a promising carrier for further research in the field of nuclear medicine. A promising sorbent was found: oxidized NDs of the STP grade (ox-STP); conditions for the fast sorption of lutetium with it in an amount equivalent to 1.2 GBq of no-carrier-added 177Lu were determined, which corresponds to the activity used in therapy. [ABSTRACT FROM AUTHOR]

Intermetallic coatings from the Ni–Al system modified with rare earth elements (REE) additions are developed to protect the Ni-based superalloys against the increasingly demanding operating conditions, like those at ultra-supercritical (A-USC) power plants. The pack cementation process is generally limited to treatment of smaller parts, but simultaneously it allows to produce thick, well adhering and easily alloyed coatings. In this experiment, the Haynes® 263 alloy was subjected to pack cementation (PC) aluminizing process. The powder bed used in this experiment was prepared in two stages, i.e., first, the Al (8 wt.%), AlCl3 (4 wt.%), and Al2O3 (88 wt.%) powders were thoroughly mixed and only then, the Yb (1.5 wt.% of the all former) was added. The coating obtained through this process was investigated using scanning and transmission electron microscopy (SEM/TEM) methods. It helped to prove that the diffusive layer consisted mostly of Al14Cr3Ni2 ζ-phase, with significant amount of Al13 (Co, Cr)4 and (Ni, Co, Cr)3Al4 larger precipitates as well as numerous smaller ones, composed of (Al, Ni, Co, Cr, Ti) or (Al, Ni, Co, Cr, Mo). The additive layer consisting of Al3Ni2 phase with up to 6 at. % Co and 2 at. % Cr was covered by a discontinuous layer of α-Al2O3 occasionally decorated with particles of the same phase. Only the very surface was found to be occupied by an amorphous Yb2O3 oxide, which formed a thin (~ 5 nm), but simultaneously a continuous layer. The latter finding is the first experimental documentation of the location of REE in the coating obtained through PC process using a powder bed modified with elements from that group. [ABSTRACT FROM AUTHOR]

To better understand the geodynamic evolution of northeastern China during the Late Mesozoic, we analyzed zircon U–Pb geochronological, Lu–Hf isotopic, and geochemical data for Early Cretaceous volcanic rocks from the southeastern margin of the Songliao Basin. Newly identified A-type rhyolite and trachyandesite yielded zircon 206Pb/238U ages of ca. 123 Ma and 117 Ma, respectively. The rhyolites are high in SiO2 (72.24–78.89 wt%) and total alkali (K2O + Na2O = 8.81–10.03 wt%), and low in MgO (0.10–0.26 wt%), CaO (0.32–0.36 wt%), Ni (0.08–2.69 ppm), and Cr (0.39–4.87 ppm) concentrations, with negative Nb, Ta, and Sr anomalies. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) and depleted in high-field-strength elements (HFSEs); the calculated Zr saturation temperatures are high (828–915 °C). The A-type rhyolites possess variable zircon εHf(t) values ranging from + 5.69 to + 10.49. Petrogenetic analysis leads us to propose that the A-type rhyolites were probably formed by partial melting of a Neoproterozoic–Early Paleozoic juvenile lower crust. The trachyandesites have Nb/Ta (14.9–17.25), Zr/Hf (35.04–42.75), Rb/Sr (0.25–0.40), and Lu/Yb (0.14–0.15) ratios that are similar to those of mantle-derived magma, indicating a mantle source. They have εHf(t) values of + 4.71 to + 7.29 and show enrichment in LILEs and LREEs, and weak depletion in HFSEs, suggesting that the parent magma originated from partial melting of a depleted lithospheric mantle, and was subsequently metasomatized by subduction-related fluids, followed by extensive fractional crystallization during the magma evolution. Combined with the temporal and spatial distribution of Late Mesozoic igneous rocks from the southeastern margin of the Songliao Basin, we propose that Early Cretaceous volcanic rocks formed in an extensional tectonic setting that was closely related to rollback of the Paleo-Pacific (Izanagi) oceanic slab. [ABSTRACT FROM AUTHOR]

The Nagaland–Manipur Hill Ophiolite (NMHO) is an NNE-SSW trending linear ophiolite zone exposed in the northeastern states of Nagaland and Manipur in India. Basaltic rocks of NMHO are geochemically divisible into two broad groups in the Zr/Ti versus Nb/Y classification diagram. Samples with TiO2 < 2 wt% and Zr = 38–118 ppm plot within the basalt field, whereas samples with TiO2 > 2 wt% plot within the alkali basalt field. The latter can be subdivided into the alkali basalt group-1 (AB-1) with Zr = ~ 200 ppm and the alkali basalt group-2 (AB-2) with Zr = ~ 400 ppm. In a normal mid-ocean ridge basalt (N-MORB) normalized trace element pattern, basalt displays a near-horizontal trend from Lu to Pr at rock/N-MORB = ~ 1 and then increases slightly from Pr to Rb, whereas alkali basalt is relatively more enriched than basalt. In the chondrite-normalized rare earth element (REE) pattern, basalt displays near-horizontal trends with (La/Yb)CN ranging between 0.78 and 1.89. On the other hand, alkali basalt displays parallel and steadily increasing enrichment trends from Lu to La [(La/Yb)CN = 11.07–17.61], with a slight drop at Eu and Sm. Mantle melting models suggest: (1) partial melting of N-MORB-like sources at degrees of melting (F) = 4–8% for basalts; and (2) partial melting of ocean island basalt (OIB)-like sources at F = 7.5–17.8% for alkali basalt. Occurrences of basalts with N-MORB-like and and alkali basalt with OIB-like signatures within the NMHO complex suggest their origin from distinct magma batches with direct or indirect involvement of the Kerguelen plume. Chondrite normalised pattern for elements Nb, Zr and REE showing estimated compositions of source S1 and residue R1 for alkali basalt (estimated using DMI modeling) and source S2 for basalt (estimated using NBM modeling) in this study. DMM and OIB (Workman and Hart 2005) values are also shown for comparison. Average abyssal peridotite value is from Niu (2004) database. [ABSTRACT FROM AUTHOR]

Phase pure Tb1–xYbxAl3(BO3)4 (x = 0 – 1) crystalline powders were prepared by the combustion synthesis method. Down-conversion experiments under UV excitation of 375 nm revealed optimal concentration of Yb x = 0.5 providing intensive green luminescence with 24% of quantum efficiency. Also up-conversion luminescence via energy transfer from Yb3+ to Tb3+ using a low power IR diode laser operating at 980 nm was achieved. Here the most powerful green emission was obtained with x = 0.1. [ABSTRACT FROM AUTHOR]

Metamorphosed dacitic porphyry dikes were first found in the western part of the Vorontsovka terrane, which is located in the Paleoproterozoic Volga–Don orogen at the margin of Archean Sarmatia and Volga–Ural cratons. The magmatic protolith age for the metadacites is ca. 2.07 Ga. These are ferrous, metaluminous calc-alkali I-type granitoids. The sodium specialization of the rocks and their low concentrations of Mg, Cr, Ni, and incompatible elements, with significant REE fractionation, the absence of Eu* anomalies, high Sr/Y ratio, remarkably high (Gd/Yb)n values (>10), and the radiogenic Nd isotopic composition indicate that the dacitic melts were derived from a juvenile mafic source. According to petrogenetic estimations, such conditions could be caused by the partial melting of depleted N-MORB basites in equilibrium with an eclogitic residue. The dacitic magmas were likely generated by the partial melting of mafic rocks at lower levels of the significantly thickened crust (>60 km) in relation to collision processes. [ABSTRACT FROM AUTHOR]

The isotopic shifts of 149Sm–150Sm and 157Gd–158Gd have often been observed in meteorites and lunar surface materials, because they result from the neutron-capture reactions associated with secondary neutrons produced by cosmic-ray irradiation. While the Sm and Gd isotopic shifts can mainly be used for the estimation of thermal neutron fluences that of 167Er–168Er has recently been applied in the estimation of epithermal neutron fluences. The systematic isotopic dataset of Sm, Gd and Er helps us to consider the details of planetary materials' cosmic-ray exposure conditions using the balance of the fluences between thermal and epithermal neutrons. This paper reviews a series of isotopic variations of Sm, Gd, and Er in association with neutron-capture reactions for the application of planetary sciences. As a new attempt and possibility for better understanding the neutron fluence and its energy distribution, the use of Yb isotopic variation is then discussed using two different data sources, namely lunar regolith and the Oklo natural reactors. Finally, the preliminary result for the precise isotopic measurement of Yb is presented from the viewpoint of chemical separation and instrumental improvement. [ABSTRACT FROM AUTHOR]

The Sanjiang Tethyan Orogen plays a pivotal role in elucidating the geodynamic processes related to the evolution of the Paleo-Tethys Ocean. Research on the Gicha Complex within this orogen is imperative for comprehending the intricate evolution of the region. This study presents new findings from zircon U‒Pb dating, Hf isotope analysis, and whole-rock elemental analyses of gabbro, olivine gabbro, and the recently discovered mylonitic rhyolite and diabase in the Gicha Complex. The zircon U‒Pb dating yields ages of 703 ± 3 Ma for the diabase, 296 ± 2 Ma for the gabbro, and 231 ± 1 and 228 ± 2 Ma for the mylonitic rhyolite, demonstrating that these rocks record the extended evolution from the breakup of Rodinia to the closure of the Paleo-Tethys Ocean. The Neoproterozoic diabase samples exhibit shoshonitic and arc-like geochemical properties, with positive zircon εHf(t) values ranging from 1.1 to 3.7 and high Th/Yb values ranging from 1.34 to 3.07, suggesting that they were generated by partial melting of enriched subduction-modified lithospheric mantle in an active continental margin. The early Permian gabbro samples are part of the tholeiitic series and exhibit low SiO2 and K2O contents; depletions in Nb, Ta and Ti; and enrichment in Pb, indicating derivation from a combination of depleted mantle peridotite and subduction-related components. The whole-rock geochemical features suggest that these rocks formed in a back-arc setting featuring a small, mature ocean basin. The mylonitic rhyolite samples exhibit weakly peraluminous characteristics (A/CNK = 0.98–1.12) with high-K calc-alkaline geochemical features. The samples are depleted in Ba, Nb, Ta, and Ti and enriched in Th, U, Pb, and LREEs and exhibit negative to positive zircon εHf(t) values ranging from − 0.5 to + 5.9, indicating that they originated from partial melting of Meso-Neoproterozoic juvenile lower crust. Geochronological, petrological, and geochemical analyses indicate that the subduction of oceanic crust occurred along the western margin of the Yangtze Block until the late Neoproterozoic (~ 703 Ma). [ABSTRACT FROM AUTHOR]

In recent years, the rare earth doped upconversion luminescent materials have been widely used in many fields. In practical applications, we observed that various dopants have distinct effects on different substances to some extent. In this context, we have successfully synthesized a dual-mode-excited Ca3TeO6 double perovskite. After introduce the Yb3+/Er3+ ions pair, the designed phosphor can emit green and red luminescence under 980 nm and 1550 nm excitation, respectively, making it suitable for diverse scientific and technological applications. The potential up-conversion mechanisms driven by different excitation sources have been investigated. Moreover, it was discovered that adjusting the molar ratio of Er3+ and Yb3+ ions enhances the performance of the studied materials, rendering them well-suited for application as a high-quality optical thermometer based on the FIR technique. Our results clearly indicate that Er3+/Yb3+ co-doped Ca3TeO6 phosphors allows for multiple optimizations and control of material properties, showcasing great potential for applications in various field. [ABSTRACT FROM AUTHOR]

In this study, trivalent rare-earth ion (Eu3+, Gd3+, and Yb3+)-substituted silicate-based bioactive glass scaffolds were prepared by robocasting method using sol–gel-derived bioactive glass powders for tissue engineering applications and cancer therapy. The structural, morphological, and mechanical properties of the prepared scaffolds as well as their in vitro bioactivity in simulated body fluid (SBF) were investigated in detail. In addition, an anticancer drug (5-FU) adsorption and release behavior of the scaffolds was studied as a function of time. In vitro, cytotoxicity and alkaline phosphatase activity were investigated using human skin fibroblast BJ and osteosarcoma SaOS-2 cells. Results showed that using lanthanide ion-containing (0.5, 1, 3, and 5 wt%) sol–gel-derived bioactive glass powders it was possible to successfully fabricate periodic, mesh-like patterned robocast glass scaffolds. All of the scaffolds prepared in the study sintered at 675 °C showed an amorphous structure. The compressive strength of scaffolds was in the range of 8.8 MPa to 13.6 MPa and the highest strength values were obtained in the Yb3+-containing scaffolds. Hydroxyapatite formation was obtained for the scaffolds immersed in SBF for 28 days. The fluorouracil adsorption amount was calculated to be ~ 25% for all types of scaffolds and the cumulative drug release was in the range of 20–25% depending on the dopant concentration. Results of the in vitro cell culture experiments revealed that all of the scaffolds fabricated in the study were not cytotoxic to fibroblast and osteosarcoma cells for up to 7 days under in vitro conditions. An increase was obtained for the ALP activities for both types of cells as the incubation time was increased. [ABSTRACT FROM AUTHOR]

Rare-earth substituted nanocrystalline hexagonal strontium ferrites with chemical formula Sr1 − xPrxFe12O19 (0 ≤ x ≤ 0.1) and Sr0.95Re0.05Fe12O19 (Re = La, Pr, Nd, Dy, Yb), were prepared by sol-gel autocombustion method. The effects of calcination temperature, rare earth ion concentration and rare earth ion radius on the structure and magnetic properties of nano-sized hexagonal strontium ferrites were investigated. X-ray diffraction (XRD) and Vibrating sample magnetometer (VSM) were applied for the systematical investigation of phase composition, crystal structure and magnetic properties of the samples respectively. The suitable calcination temperature of nanocrystalline strontium ferrites was determined to be 900 ℃, which was attributed to the relationship between the calcination temperature and the rotation of the domain wall. The coercivity (Hc) of Sr1 − xPrxFe12O19 reached a maximum at x = 0.05 and the saturation magnetization (Ms) decreased with the increase of Pr substituting content. This reduction followed the spin canting and magnetic dilution which results in the dislocation of super exchange interactions. For Re-substituted samples, the Hc increased with the decreasing ionic radius of substituted elements, while the Ms slightly decreased in comparison to the non- substituted sample. The synthesized samples could be used in permanent magnets, high-density magnetic recording medium, and microwave equipment. [ABSTRACT FROM AUTHOR]

V2O5 and 1 mol% RE-doped V2O5 (RE = La, Er, Yb) thin films were prepared using the sol–gel method. The structure and morphology of the prepared films were investigated using XRD, HRTEM, SAD electron microscopy, FESEM, and EDS. XRD analysis revealed a strong c-axis orientation and noncrystalline structure. Gaussian fitting of the XRD peaks indicates a decrease in the crystallite size with RE doping, which is attributed to the increased internal stress and lattice distortion. TC analysis showed a preferred orientation along the c-axis. HRTEM observations confirmed the crystallinity of the nanosheets. The absorption, transmittance, and reflectance spectra were measured for normal-incidence light in the wavelength range 190–1100 nm. The obtained spectra were used to investigate the linear and non-linear optical properties via various optical parameters, including static refractive index, optical band gap energy, Urbach band tail energy, dispersion energy parameters using the Wemple and DiDomenico (WDD) single-oscillator model, nonlinear refractive index and first and third optical susceptibilities. The doped films exhibited lower optical bandgaps and the investigated linear and nonlinear optical parameters showed significant effects in RE-doped films compared to pure V2O5, indicating potential for various optical applications. The optical limiting of the prepared films was studied using two laser sources (650 nm and 533 nm), revealing significant optical limiting for RE-doped films compared with pure V2O5 films, where the optical limiting effect is related to the oscillator strength and Urbach band tail energy. This study shows that rare-earth doping has a significant impact on the structural and optical properties of V2O5 thin films, making them promising materials for various applications, such as optoelectronic devices and nonlinear optical applications. [ABSTRACT FROM AUTHOR]