Pr Yb Research Articles

Flux growth and characterization of gallium-rare earth borates

YGa3(BO3)4 single crystals were grown from a K2Mo3O10-based flux, and also RGa3(BO3)4 (R = Y, Pr–Yb) spontaneous crystals (RGB) were obtained by a high-temperature flux growth technique from a complex R2O3–Bi2O3–B2O3–Ga2O3 solvent.

Synthesis of coral-like structures of Pr–Yb co-doped YIG: Structural, optical, magnetic and antimicrobial properties

Coral-like structures of the Y3–xPrxFe5–yYbyO12, (0.00 ≤ x ≤ 0.04), (0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal structure formation, without any secondary phase. It is shown that, the relatively large ionic radius of the dopant cations results in an expansion of the lattice parameter, variations in the Iona‒O‒Iond angle, Iona‒O, Iond‒O and Ionc‒O bond distances and decrease in the average crystallite size. Fourier transform infrared (FTIR) and Raman measurements are essential to testify the single-phase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, respectively. The morphological study, energy dispersive spectroscopy (EDS) spectra and textural properties show coral-like structures, peaks associated with Pr3+ and Yb3+ atoms and the effect of dopants on surface area, diameter, and pore volume, respectively. The optical analysis from diffuse reflectance spectra witnessed an increase in the optical gap band, a decrease in Urbach energy and blue shift in the charge transfer, correlated with the expansion of the unit cell due to the dopant's insertion in the YIG structure. A typical ferrimagnetic behavior is exhibited by the Y3–xPrxFe5–yYbyO12 compound. The saturation magnetization (Ms), cubic anisotropy constant (K1) and coercive field (Hc) increase with the Pr3+ cations content, as consequence of their magnetic nature and distribution around of Fe3+ ions due to the coexistence with the Yb3+. Finally, for the first time, antibacterial tests by mean of the direct contact method were performed for YIG co-doped with Pr3+ and Yb3+ and it is shown that, relatively high dosages of Pr3+ cations favored the activity against S. aureus, therefore, a new biological property for YIG doped with rare earths is presented.

Complex Rare-Earth Tantalates with Pyrochlore-Like Structure: Synthesis, Structure, and Thermal Properties

The existence of a wide range of pyrochlore-like (PL) Ln2FeTaO7 compounds (Ln = Pr–Yb, including Y) with a hexagonal structure (space group R$$\overline{3}$$) was shown. Two new low-temperature methods for the synthesis of Ln2FeTaO7 were developed to reduce the production temperature and time, namely, coprecipitation followed by annealing and synthesis in molten salts NaCl/KCl. The synthesis of PL phases was found to involve the formation of a nanocrystalline metastable fluorite phase, the fluorite irreversibly transforming to a PL phase as the crystallization time or temperature increases. No other transitions in Ln2FeTaO7 were recorded by DSC up to the melting point of 1320–1450°C (depending on the composition of the Ln2FeTaO7 compound). The isobaric heat capacity Cp(T) was measured and the thermodynamic functions (entropy, enthalpy increment, and reduced Gibbs energy) were calculated in the temperature range 5–1300 K for Y2FeTaO7 by the way of example. In the low-temperature region of 2–25 K, an abnormal behavior of Cp(T), apparently related to the Y2FeTaO7 magnetic transition, was detected.

A Sensor for Trace H2O Detection in D2O

Summary PCM-22, a metal-organic framework material comprising triphenylphosphine and Ln 3+ ions (Ln = Pr–Yb), exhibits solid-state luminescence at room temperature. Mixed-metal versions of PCM-22 that contain controlled amounts of Eu 3+ , Gd 3+ , and Tb 3+ function as highly sensitive, broad-scope solid-state sensors that can rapidly identify unknown solvents by providing a unique eight-factor fingerprint. The sensors allow for immediate solvent identification via color changes that are obvious to the naked eye and also permit quantitative chemical analysis by uncomplicated spectrophotometry. These same materials achieve quantitative detection of H 2 O in D 2 O from 10 to 120,000 ppm. The detection of trace H 2 O is also demonstrated in a range of common solvents, including those incompatible with conventional laboratory titration methods.

An active-core/active-shell structure with enhanced quantum-cutting luminescence in Pr-Yb co-doped monodisperse nanoparticles.

Monodisperse Pr(3+)/Yb(3+):NaGdF₄@NaYF₄ active-core/inert-shell nanoparticles, which exhibit efficient near-infrared quantum-cutting luminescence, are successfully prepared. In order to relieve the adverse effect caused by concentration quenching in the core, the extra Yb(3+) ions are introduced into the shell, forming an active-core/active-shell structure which leads to a much intensified near-infrared emission.

ChemInform Abstract: Effect of Inclining Strain on the Crystal Lattice Along an Extended Series of Lanthanide Hydroxysulfates Ln(OH)SO4 (Ln: Pr—Yb, Except Pm).

AbstractThe title compounds are hydrothermally prepared from aqueous solutions of Ln2(SO4)3 (Ln: Pr—Yb, except Pm) and NaOH (autoclave, 170 °C, 10 d).

Synthesis and structural characterization of a series of lanthanide stannate pyrochlores

A simple hydrothermal method has been employed to prepare a series of lanthanide stannate pyrochlores Ln 2Sn 2O 7 (Ln=Y, La, Pr–Yb) at a relatively low temperature of less than 200 °C successfully. On the basis of structural characterizations by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) absorption spectroscopy and Raman spectroscopy, it was found that the positions of bands in vibrational spectra are sensitive to the ionic radius of Ln 3+, and the linear relationship can be seen between the frequency of Sn–O stretching mode and the lanthanide ionic radius in IR spectrum, as well as the frequency of O–Sn–O bending mode and the lanthanide ionic radius in Raman spectrum.

Structural studies of lanthanide complexes with tetradentate nitrogen ligands

Complexes have been synthesised with bis(2-pyridine carboxaldehyde) ethylenediimine ( 1) and bis(2-pyridine carboxaldehyde)propylene-1,3-diimine ( 2) with all of the available lanthanide trinitrates. Crystal structures were obtained for all but one complex with 1 and for all but one complex with 2. Four distinct structural types were established for 1 but only two for 2, although in all cases the structures contained one ligand bound to the metal in a tetradentate fashion. With 1, the four different structures of the lanthanide(III) nitrate complexes included 11-coordinate [Ln( 1)(NO 3) 3(H 2O)] for Ln = La; 10 coordinate [Ln( 1)(NO 3) 3(H 2O)] with one monodentate and two bidentate nitrates for Ln = Ce, then 10-coordinate [Ln( 1)(NO 3) 3] for Ln = Pr–Yb with three bidentate nitrates; and 9-coordinate [Ln( 1)(NO 3) 3] with one monodentate and two bidentate nitrates for Ln = Lu. On the other hand for 2 only two distinct types of structure are obtained, the first type with Ln = La–Pr and the second type for Ln = Sm–Lu, although all are 10-coordinate with stoichiometry [Ln( 2)(NO 3) 3]. The difference between the two types is in the disposition of the ligand relative to the nitrates. With the larger lanthanides La–Pr the ligand is found on one side of the coordination sphere with the three nitrate anions on the other. In these structures, the ligand is folded such that the angle between the two pyridine rings approaches 90°, while with the smaller lanthanides Sm–Lu, two nitrates are found on one side of the ligand and one nitrate on the other and the ligand is in an extended conformation such that the two pyridine rings are close to being coplanar. In both series of structures, the Ln–N and Ln–O bond lengths were consistent with the lanthanide contraction though there are significant variations between ostensibly equivalent bonds which are indicative of intramolecular hydrogen bonding and steric crowding in the complexes.

Energy transfer and 1.3 μm emission in Pr–Yb codoped tellurite glasses

To seek the possibility of an efficient 1.3 μm amplifier in oxide materials, the concentration and temperature dependence of fluorescence properties of the Pr 3+ : 1G 4 → 3H 5 at 1.3 μm and Yb 3+: 2 F 5/2 → 2 F 7/2 at 1 μm were investigated in codoped tellurite glasses with compositions of 75TeO 2–20ZnO–5Na 2O– xPr 2O 3– yYb 2O 3. By 0.97 μm pumping, the 1.3 μm emission of Pr 3+ was sensitized by the Yb → Pr energy transfer. The lifetime obtained by 1.02 μm emission of Yb 3+ at room temperature was concentration quenched with the presence of only 0.1 mol% Pr 2O 3. The energy transfer efficiency from Yb to Pr in a codoped glass was found to be more than 90% even in the glass of [Yb]/[Pr]>100. With increasing temperature, the Yb-lifetime in singly doped glass increased and that in codoped glass decreased. These results can be explained by assuming rapid energy migration between Yb ions and promotion of Yb 3+ : 2 F 5/2 → Pr 3+: 1 G 4 transfer at higher temperature.

Description of ligand field splitting in terms of density functional theory: Split levels of the lowest-lying subterms of the 4fn−16s2 (n=3–14) configurations in lanthanide monofluorides LnF (Ln=Pr–Yb)

The split levels associated with the lowest-lying subterms of the 4fn−16s2 (n=3–14) configurations of lanthanide monofluorides LnF (Ln=Pr–Yb) were calculated by employing the combined ligand field and density functional theory (CLDT) method recently proposed. The 288 calculated split levels are in excellent agreement with experiment and hence shows that the CLDT method can accurately reproduce the low-lying electronic excited states of lanthanide compounds. To quantitatively describe the low-lying electronic states of a lanthanide compound, therefore, the effective ligand potential must include the Coulomb and exchange-correlation potentials of the compound as well as the pseudopotentials of the ligands.

Thermal decomposition behavior of heteronuclear complexes Ln[Fe xCo 1− x(CN) 6]4H 2O (Ln=Pr–Yb)

Heteronuclear complexes Ln[Fe x Co 1− x (CN) 6]4H 2O (Ln=Pr–Yb) were synthesized and the crystal structures of thermally decomposed complexes were investigated. For Ln=Pr–Gd, only perovskite-type oxides (crystal system: orthorhombic) were formed even when the complexes decomposed at 800°C. The lattice constants ( a, b and c) of the oxides increased linearly with increasing Fe/Co ratio. On the other hand, for Ln=Dy–Yb, the Ln 2O 3 phase was obtained as the major product, especially for lower Fe content. The single phase of the perovskite-type oxide could not be obtained even for x=1, although the diffraction peaks due to the perovskite structure gradually increased with increasing Fe content.

Rare earth acetylacetonate complexes with 2,7-dimethyl-1,8-naphthyridine

Rare earth acetoacetonate complexes of the type Ln(acac) 32,7-dimethyl-1,8-naphthyridine where Ln = Pr  Yb have been synthesized. The compounds have been characterized by elemental analyses, molar conductances and IR spectra (4000-200 cm −1). The molar conductances and IR spectra show all ligands are coordinated to the metals. Evidence suggesting a dodecahedral geometry for these 8-coordinate complexes which contain four- and five-membered chelate rings is presented.