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A series of polycrystalline YMn1-xRuxO3 (0≤x≤0.2) samples were prepared by traditional solidstate reaction method. Effects of doping on the microstructures and magnetic properties were investigated. Microstructural results reveal that samples crystallize in a single hexagonal structure with P63cm group for x≤0.1. Lattice parameters a, c, and unit-cell volume of YMn1-xRuxO3 are found to increase with doping content, which are ascribed to the larger radius of Ru3+ than that of Mn3+. Weak ferromagnetism is found and is enhanced with increasing doping concentration x. The bond angles of Mn-O3-Mn and Mn-O4-Mn are changed in the opposite trends, which break the Mn-Mn exchange interaction, thus the antiferromagnetic ordering. The MnO5 bipyramid is found to be relieved and the trimerization of Mn ions is weakened. These structural modifications result in the increase of weak ferromagnetism ordering in samples. [ABSTRACT FROM AUTHOR]

Dual-mode luminescence (downshifting-DS and upconversion-UC) properties of Pr3+/Yb3+ co-doped Y1-xGdxNbO4 (x = 0.0, 0.5, and 1.0) phosphors synthesized by solid state reaction technique have been explored with and without Gd3+ ion. The structural characterizations (XRD, SEM, and FTIR) confirm the pure phase of YNbO4 phosphor. Further, with the Gd3+ ion co-doping, the YNbO4 phosphors having a random shape and the large particle size are found to be transformed into nearly spherical shape particles with the reduced particle size. The optical band gaps (Eg) of Y1-xGdxNbO4 (x = 0.00, 0.25, 0.50, and 1.00) calculated from UV-Vis-NIR measurements are ~3.69, 4.00, 4.38, and 4.44 eV, respectively. Moreover, YNbO4 phosphor is a promising blue emitting material, whereas Y1-x-y-zPryYbzGdxNbO4 phosphor gives intense green, blue, and red emissions via dual-mode optical processes. The broad blue emission arises due to (NbO4)3- group of the host with λex = 264 nm, whereas Pr3+ doped YNbO4 phosphor gives dominant red and blue emissions along with comparatively weak green emission on excitation with λex = 300 nm and 491 nm. The concentration dependent variation in emission intensity at 491 nm (³P0→³H4 transition) and 612 nm (¹D2→³H4 transition); at 612 nm (¹D2→³H4 transition) and 658 nm (³P0→³F2 transition) of Pr3+ ion in YNbO4 phosphor with λex = 300 nm and 491 nm excitations, respectively, has been thoroughly explored and explained by the cross-relaxation process through different channels. The sensitization effect of Bi3+ ion co-doping on DS properties of the phosphor has also been studied. The observed DS results have been optimized by varying the concentration of Pr3+ and Bi3+ ions, and the results are explained by the well-known simple band structure model. The study of Gd3+ co-doping reveals noticeable differences in DS characteristics of Y1-xPrxNbO4 phosphors: the overall decrement and increment (except for 612 nm emission) in intensity of DS emission on excitation with λex = 264 nm and 491 nm, respectively. These observations have been thoroughly explained, and the ¹D2→³H4 transition (612 nm) of Pr3+ ion is found to be strongly dependent on surrounding environment of the host matrix. The UC properties of Y0.95-xPrxYb0.05NbO4 phosphors have been explored using Near Infra-Red (NIR) excitation. The material gives intense green and relatively weak blue and red UC emissions with kex = 980 nm. Interestingly, the UC emission intensity is further enhanced in the case of Y0.949-xPr0.001Yb0.05GdxNbO4 phosphors. In addition, the less explored laser induced heating effect with the pump power as well as the irradiation time on the UC emission has been explored in Y0.949-xPr0.001Yb0.05GdxNbO4 (x = 0, 0.5, and 0.949) phosphor samples, and subsequently, this feature has been found to be superior for Gd0.949Pr0.001Yb0.05NbO4 phosphor. The comparative study between the two hosts, viz., YNbO4 and GdNbO4 shows that GdNbO4 is better than YNbO4 for UC emission behavior; however, a reverse is observed as for as DS behavior is concerned only for the particular excitation wavelength (λex = 264 nm). [ABSTRACT FROM AUTHOR]

A series of polycrystalline YMn1-xRuxO3 (0≤x≤0.2) samples were prepared by traditional solidstate reaction method. Effects of doping on the microstructures and magnetic properties were investigated. Microstructural results reveal that samples crystallize in a single hexagonal structure with P63cm group for x≤0.1. Lattice parameters a, c, and unit-cell volume of YMn1-xRuxO3 are found to increase with doping content, which are ascribed to the larger radius of Ru3+ than that of Mn3+. Weak ferromagnetism is found and is enhanced with increasing doping concentration x. The bond angles of Mn-O3-Mn and Mn-O4-Mn are changed in the opposite trends, which break the Mn-Mn exchange interaction, thus the antiferromagnetic ordering. The MnO5 bipyramid is found to be relieved and the trimerization of Mn ions is weakened. These structural modifications result in the increase of weak ferromagnetism ordering in samples. [ABSTRACT FROM AUTHOR]

By the reaction of Y(NO3)3 and {Et4N}[VO3] in organic media, yttrium‐containing polyoxovanadates are synthesized and classified into sandwich‐type {Et4N}5[Y(H2O)n(V4O12)2] (1, n = 0–2), ring‐type {Et4N}6[Y(V9O27)] (2), and cage‐type {Et4N}8[Y4(OH)4V20O58] (3). Both compounds 1 and 2 contain a mononuclear yttrium cation. A yttrium cation in 1 is sandwiched by two [V4O12]4–, while that in 2 is surrounded by a single [V9O27]9– ring. In acetonitrile, both species 1 and 2 are formed simultaneously. The dominant species in solution are controlled by the presence of additives. The addition of an excess amount of pyridine drives the formation of 1, while in the presence of water or {Et4N}[VO3], the formation of 2 is preferable. Compound 3 possesses a cubane‐type tetranuclear yttrium core, [Y4(OH)4]8+, wrapped by a polyoxovanadate framework. The spherical polyoxovanadate framework of 3 exhibits new types of inorganic coordination ligands and can include a cubane unit in the framework. The vanadate framework of 3 consists of condensed [V11O33]11– rings sharing three‐coordinate VO4 units as a bridgehead, as in an adamantane framework. Sandwich‐, ring‐, and cage‐type yttrium‐containing polyoxovanadates with quite different arrangements are synthesized, and their structures are manipulated stoichiometrically by using additives. [ABSTRACT FROM AUTHOR]

A robust porous structure is often needed for practical applications in electrochemical devices, such as fuel cells, batteries, and electrolyzers. While templating approach is useful for the preparation of porous materials in general, it is not effective for the synthesis of oxide‐based electrocatalysts owing to the chemical instability of disordered porous materials thus created. Now the synthesis of phase‐pure porous yttrium ruthenate pyrochlore oxide using an unconventional porogen of perchloric acid is presented. The lattice oxygen defects are formed by the mixed‐valence state of Ru4+/5+ through the partial substitution of Ru4+ with Y3+ cations, leading to the formation of mixed B‐site Y2[Ru1.6Y0.4]O7−δ. This porous Y2[Ru1.6Y0.4]O7−δ electrocatalyst exhibits a turnover frequency (TOF) of 560 s−1 (at 1.5 V versus RHE) for the oxygen evolution reaction, which is two orders of magnitude higher than that of the RuO2 reference catalyst (5.41 s−1). [ABSTRACT FROM AUTHOR]

Herein, ortho‐methylated bipyridines are introduced as initiators in 2‐aminoalkoxy‐bis (phenolate) yttrium complexes. For this C−H bond activation (ONOO)tBuY(CH2TMS)(thf) (1) (TMS=trimethylsilyl) is reacted with the respective bipyridine to obtain complexes (ONOO)tBuY(6‐Me2bpy) (2) and (ONOO)tBuY(6‐Mebpy) (3). Both complexes were tested first in rare‐earth metal‐mediated group‐transfer polymerization of 2‐vinylpridine (2VP). Complex 3 was further tested in block copolymerizations of 2VP and diethyl vinylphosphonate. The obtained initiator‐P2VP‐PDEVP‐block copolymers can selectively react with Re(CO)5Cl at their bipyridine end‐group. The obtained rhenium functionalized block copolymers are able to self‐assemble to unimodal micelles in water, representing a possible carrier for hydrophobic metal containing complexes into cells. Furthermore, the Re‐block copolymers sustain activity in the photocatalytic homogeneous CO2 reduction and their performance exceed the catalytic activity of the analogue polymer‐free system [Re(CO)3(6‐Mebpy)Cl] (4). Versatile blocks: Bipyridine‐P2VP‐PDEVP‐block copolymers are synthesized via REM‐GTP. The bpy end‐groups can serve as ligands for metal complexation, which is shown by complexation of [Re(CO)5Cl]. The obtained Re‐block copolymers can assemble as micelles as well as photocatalytically reduce CO2. [ABSTRACT FROM AUTHOR]

The possibility to attain a discrete β -tricalcium phosphate ( β -Ca 3 (PO 4 ) 2 )/yttria (Y 2 O 3 ) composites starting from the solution based precursors were deliberated. The sequential steps of calcination temperature and the associated phase changes to yield a pure form of β -Ca 3 (PO 4 ) 2 /Y 2 O 3 were elaborated through a wide range of analytical techniques. Alteration in the precursor concentrations yielded β -Ca 3 (PO 4 ) 2 /Y 2 O 3 composite with a wide range of individual compositional ratios. The advanced crystallization of Y 2 O 3 is evident whereas the delayed formation of β -Ca 3 (PO 4 ) 2 is mainly contributed by the sluggish phase transition of calcium deficient apatite. The formation of pure β -Ca 3 (PO 4 ) 2 /Y 2 O 3 composite is attained only at 1500 °C, where Y 3+ prefers accommodation at the Ca 2+ (1), Ca 2+ (2) and Ca 2+ (3) sites of β -Ca 3 (PO 4 ) 2 structure. The selective mechanical properties determined from the indentation technique implied a detrimental role of Y 2 O 3 in the resultant mechanical data of β -Ca 3 (PO 4 ) 2 /Y 2 O 3 composites. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The yellow-emitting Y 2 BaAl 4 SiO 12 :Ce3+ phosphors were synthesized by a sol-gel method. • Y 2 BaAl 4 SiO 12 :Ce3+ phosphors can be efficiently excited under the blue light. • Y 2 BaAl 4 SiO 12 :Ce3+ phosphors exhibit excellent yellow emission under blue light. • Y 2 BaAl 4 SiO 12 :Ce3+ phosphors are promising yellow phosphor for the fabrication of WLED. Abstract Yellow-emitting Y 2 BaAl 4 SiO 12 :Ce3+ (YBAS:Ce3+) phosphors were synthesized by a sol-gel method followed by annealing at high temperature. The phase purity of the YBAS:Ce3+ phosphors was confirmed by X-ray diffraction analysis. The emission characteristics of YBAS:Ce3+ phosphors were investigated by measuring their photoluminescence excitation and emission spectra. These phosphors can be efficiently excited with blue light that induced an intense yellow emission peak centered at 530 nm. White light-emitting diodes (WLEDs) were fabricated using the synthesized YBAS:6Ce3+ phosphors. The CIE chromaticity coordinates of YBAS:6Ce3+ and the fabricated WLEDs were located at the yellow (0.391, 0.563) and cool white-light (0.265, 0.326) regions, respectively. [ABSTRACT FROM AUTHOR]

In the present study, a calcium- and nickel-doped yttrium chromates (YCCN)-based, conductive-protective layers for metallic interconnects used in the intermediate-temperature solid oxide fuel cells (IT-SOFCs) were investigated. Synthesis of Y0.8Ca0.2Cr1−xNixO3 (x = 0; 0.15 and 0.3) powders was performed using a wet chemistry method with two different complexing agents: ethylenediaminetetraacetic acid and glycine. Based on the result of thermal analysis of obtained precursors, optimal conditions of the calcination process were determined. Powders were then milled, compacted and sintered at different temperatures using free sintering method, into series of dense, polycrystalline sinters. The use of glycine precursor allowed obtaining a single-phase material in all cases. Based on the electrical and sintering properties, the Y0.8Ca0.2Cr0.85Ni0.15O3 material was selected for further studies. It was deposited using cost-effective screen-printing method on the Crofer 22APU ferritic stainless steel. To investigate properties and suitability of the resulting layer/steel system for IT-SOFCs applications, the high-temperature, dual-atmosphere studies were carried out for the first time for ceramic/metallic system, in conditions as close as possible to actual working conditions of the fuel cell. The layer exhibited high stability and good protective properties. The area-specific resistance of the studied ceramic layer/metallic substrate composite was determined, with the obtained value of 0.0366 Ω cm2 being within the arbitrary limit set for these materials (0.1 Ω cm2). The results show that the investigated materials are suitable for the projected application. [ABSTRACT FROM AUTHOR]

Dy 3+ -doped yttrium orthosilicate (Y 2 SiO 5, abbreviated YSO) phosphors were synthesized: (1) by conventional high temperature solid-state method using two types of fluxes: lithium fluoride (LiF) and boron oxide (B 2 O 3 ); (2) by metal alkoxide sol-gel method using isopropoxide assisted co-precipitation with subsequent annealing to explore its possible application in high-temperature thermometry. It was experimentally observed that the use of LiF flux affects the luminescent properties due to improvement of the crystal quality of crystallites and co-doping Li + and F - ions. Herein, a strategy involving the use of different fluxes and concentration of Dy 3+ ions has been developed to achieve high photoluminescence (PL) intensity and high intensity ratio of different PL peaks. The case of incorporated LiF in the host crystal lattices revealed strong enhancement of luminescence intensity of YSO:Dy (more than three times higher at 293 K) compared to the luminescence intensity of the phosphors synthesized with B 2 O 3 . Based on the results of high temperature measurements, it can be stated that YSO:Dy is a favorable phosphor for high temperature measurement, with a temperature sensitivity range comparable to YAG:Dy but with a lower PL decay time which is reduced by about 60%. For temperatures up to 1250 K the intensity ratio approach offers better measurement capabilities while the temperature sensitivity above 1250 K is superior for the decay time approach. [ABSTRACT FROM AUTHOR]

Compounds Y2SiO4Q (Q = S, Se) are obtained by the interaction of oxides and elemental substances in cesium chloride flux. The structures of these compounds are determined by the single crystal XRD analysis. These compounds isostructural and crystallize in the space group Pbcm with the following parameters: Y2SiO4S (I) a = 6.0462(8) Å, b = 6.8976(9) Å, c = 10.6558(13) Å, V = 444.39(10) Å3; Y2SiO4Se (II) a = 5.9935(7) Å, b = 6.9216(8) Å, c = 10.7688(12) Å, V = 446.74(9) Å3. The measured fluxing points are 1650±15 °С for I and 1850±15 °С for II. [ABSTRACT FROM AUTHOR]

The yttrium methanediide complex [Y(BIPM)(I)(THF)2] (BIPM = {C(PPh2NSiMe3)2}) was reacted with a series of potassium bis(silyl)amides to produce heteroleptic complexes by salt metathesis protocols. The methanediide complexes [Y(BIPM)(N")(THF)] (1; N" = {N(SiMe3)2}) and [Y(BIPM)(N**)(THF)] (2; N** = {N(SiMe2tBu)2}) were obtained for those relatively small bis(silyl)amides. Complex 2 undergoes thermal decomposition under vacuum to yield the methanide cyclometalate complex [Y(H-BIPM){N(SitBuMe2)(SitBuMeCH2)-κ²-N,C}] (3) as part of an otherwise intractable mixture of products. Complex 3 was also observed in trace amounts in mixtures of [Y(BIPM)(I)(THF)2] and KN**. In contrast, [Y(BIPM)(I)(THF)2] reacted with the more sterically demanding potassium bis(silyl)amides KN*† (N*† = {N(SiMe2tBu)(SiiPr3)}) and KN†† (N†† = {N(SiiPr3)2}) to afford the methanide cyclometalate complexes [Y(H-BIPM){N(SiiPr3)(SitBuMeCH2)-κ²-N,C)}] (4) and [Y(H-BIPM){N(SiiPr3)[SiiPr2(CHMeCH2)]-κ²-N,C}] (5), respectively. Complexes 1-5 were characterized as appropriate by multinuclear NMR and FTIR spectroscopy, elemental analyses, and single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Nanorods of YP 0.8 V 0.2 O 4 :Sm 3+ have been synthesized under hydrothermal conditions. Substitution of vanadium (V 5+ ) sites in YVO 4 by phosphorus ions (P 5+ ) has been confirmed by Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. Careful selection of Sm 3+ concentration in YP 0.8 V 0.2 O 4 enables to achieve the controlled energy transfer from the VO 4 3− absorption to the excited states of Sm 3+ ions. The controlled energy transfer has been confirmed from the steady state luminescence and decay lifetime studies of VO 4 3− emission. With the controlled retention of VO 4 3− emission, tuning of light emission from the singly (Sm 3+ ) doped YP 0.8 V 0.2 O 4 nanorods is realized. At a particular doping concentration of Sm 3+ (1.25 at.%), a nearly white light emission is observed. The quantum yield of this nearly white light emission is found to be ∼28%. Tunability of the light and white light emission are supported by CIE chromaticity. The energy transfer efficiency from the VO 4 3− absorption to the excited states of Sm 3+ ion in YP 0.8 V 0.2 O 4 reaches upto ∼86% with the doping concentration of 2.25 at.%. [ABSTRACT FROM AUTHOR]

Yttrium aluminum borate (YAB) powders prepared by sol-gel process have been investigated to understand their photoluminescence (PL) mechanism. The amorphous YAB powders exhibit bright visible PL from blue emission for powders calcined at 450 °C to broad white PL for higher calcination temperature. Thanks to 13C labelling, NMR and EPR studies show that propionic acid initially used to solubilize the yttrium nitrate is decomposed into aromatic molecules confined within the inorganic matrix. DTA-TG-MS analyses show around 2 wt % of carbogenic species. The PL broadening corresponds to the apparition of a new band at 550 nm, associated with the formation of aromatic species. Furthermore, pulsed ENDOR spectroscopy combined with DFT calculations enables us to ascribe EPR spectra to free radicals derived from small (2 to 3 rings) polycyclic aromatic hydrocarbons (PAH). PAH molecules are thus at the origin of the PL as corroborated by slow afterglow decay and thermoluminescence experiments. [ABSTRACT FROM AUTHOR]

We present here an effective and facile method to synthesize hierarchical sponge-like mesoporous trivalent cerium (Ce 3+ ) doped cubic (YAG (Y 3 A 5 O 12 )) and monoclinic (YAM (Y 4 A 2 O 9 )) yttrium aluminium oxide (YAlO) by a single step self propagating low temperature combustion technique without any post heating. The X-ray diffraction study revealed the formation of YAG and YAM structures and optimum incorporation of dopant is confirmed through precipitated secondary phase at higher Ce 3+ concentration. Raman spectra of undoped and Ce 3+ doped YAlO shows the characteristics peaks of YAG and YAM structure. The field emission scanning electron micro graphs (FESEM) reveal highly porous sponge-like surface with individual pore size of about 12–15 nm. The photoluminescence studies show efficient single band emission spectra centered at 568 and 550 nm for Ce 3+ doped YAG and YAM respectively due to intra-shell transitions of the rare earth atom, compared to negligible emission in visible region for undoped YAlO due to defects present in the host lattice. Influence of dopant and the changes observed in structural, morphological and luminescence studies due to differences in crystal field environment (cubic and monoclinic) are explained in detail. Such highly stable mesoporous material with luminescence in visible region is suited for applications in illumination devices like white LEDs for indoor and outdoor lighting and also high end biomedical applications such as tumor targeting. [ABSTRACT FROM AUTHOR]

A set of Y 2 Mo 4 O 15 compounds doped with 0.1–30% Pr 3+ was synthesized by conventional high temperature solid state synthesis. The structural, morphological and optical characteristics of the compounds were investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) analysis, thermal quenching (TQ), photoluminescence (PL) and fluorescence lifetime techniques. It turned out that Pr 3+ emission spectra are very sensitive to the concentration and temperature in the Y 2 Mo 4 O 15 host matrix. Samples showed mainly red and deep red luminescence when excited with blue radiation. A severe concentration quenching was observed in samples with higher Pr 3+ content due to cross relaxation. Y 2 Mo 4 O 15 :Pr 3+ luminescent materials possess rather unique emission spectra, which can be tuned by adopting the appropriate Pr 3+ concentration and/or temperature. Thus these materials could be used as luminescent security markers where such properties are desirable. [ABSTRACT FROM AUTHOR]

Amine elimination of Y[N(SiHMe2)2]3(THF)2with the imino-functionalized indenyl ligand C9H7CH2CH = N-2,6-iPr2C6H3in 1:1 and 1:2 molar ratio afforded the mono-indenyl-ligated yttrium bis(silylamide) complex (C9H6CH2CH = N-2,6-iPr2C6H3)Y[N(SiHMe2)2]2(4) and the neutral yttrium complex (C9H6CH2CH = N-2,6-iPr2C6H3)(C9H6CH = CH-N-2,6-iPr2C6H3)Y (5), respectively. Both complexes were characterized by elemental analysis and NMR. X-ray single crystal structural diffraction showed that the central metal in5is four-coordinated by two indenyl ligands and two nitrogen atoms in η5/κ1-mode, if the indenyl ring is regarded as occupying an independent vertex. In the presence of AliBu3and activated by one equimolar amount of [Ph3C][B(C6F5)4], complex4showed activity toward syndiospecific polymerization of styrene. [ABSTRACT FROM PUBLISHER]

We fabricated polycrystalline yttrium-iron-garnet (Y 3 Fe 5 O 12 , YIG) samples using the sol-gel synthesis method to develop an energy harvesting material based on the spin Seebeck effect. We confirmed that crystallization occurred during calcination at 850 °C and that only the polycrystalline YIG structure was formed. We found that a sintering process at 1400 °C not only increased the size of the YIG particles and the densification of their microstructure but also enhanced their saturation magnetization (M s ) and dramatically reduced their coercivity (H c ). A mechanical pressing process was carried out between the calcination and sintering treatments to prepare a free-standing YIG fillet sample. We found that M s was enhanced by almost three times without an associated reduction in H c . We found that mechanical pressing assists the oxidation reaction during the subsequent sintering process by increasing the surface energy and densification before the heat treatment. [ABSTRACT FROM AUTHOR]

Synthesis of negative and near-zero thermal expansion powders with low degree of agglomeration is one of the major challenges in their applications. In this research, Y 2 W 3 O 12 was synthesized via two soft-chemical approaches, co-precipitation by mixing reactants and modified reverse strike co-precipitation, to assess the effect of these methods on the agglomeration degree of powders. Chemical composition of amorphous precursors was estimated based on charge neutrality principle, carbon-hydrogen-nitrogen (CHN) and thermogravimetric analyses. It was demonstrated that both precursors are oxyhydroxynitrate compounds, determined as Y 2 W 3 O y (OH) z (NO 3 ) x · n H 2 O. Both co-precipitation methods presented similar particle sizes and agglomeration degrees. The applied calcination conditions caused the formation of necks and hard agglomerates and were critical factors for the final agglomerated state of the Y 2 W 3 O 12 powders. The formation of Y 2 W 3 O 12 submicronic powders in the range of 0.60–0.70 µm was verified by laser diffraction and field-emission scanning electron microscopy analyses. X-ray powder diffraction patterns, at room temperature, of hydrated Y 2 W 3 O 12 revealed predominantly the presence of monoclinic phase, while the monoclinic to orthorhombic phase transition was detected by dilatometry. [ABSTRACT FROM AUTHOR]

Effect of In ion substitutions on yttrium iron garnet samples' morphology, magnetic properties and dc electrical resistivity was examined closely and reported in this study. A series of polycrystalline garnet ferrites with composition of YFeInO (0 ≤ x ≤ 0.5) were prepared by using the mechanical alloying technique. The morphological properties of the samples was analysed by using a TEM, XRD, FESEM and EDX. The electrical dc resistivity of the samples was investigated as a function of temperature and composition by using a Picoammeter, the complex permeability was analysed by using an Impedance Materials Analyzer meanwhile microwave properties was measured by using VNA. The lattice constant increases as In content increases which can be understood by the difference in ionic radii of In ions replacing the smaller Fe ions. The grain size also increased with In content, indicating that the In ion acts as a grain growth promoter. Both complex permeability components, µ′ and µ″ reaching about 92.75 and 85.03 respectively at x = 0.3; later decreased with further In substitution. This result is synchronized with FMR linewidth which manifests magnetic loss of the samples. By correlating the phase analysis, morphology, electrical resistivity and complex permeability results, it is believed that there was an increase in number of crystalline-growth regions with increasing In content, which together increased a total mass of ferromagnetic grains with the latter starting to dominate the samples. The results also showed that In ions increase the dc resistivity of the system. [ABSTRACT FROM AUTHOR]

Yttrium–transition metal–magnesium (indium) Heusler phases YPd2Mg, YPd2In, YAg2Mg, YAg2In, YAu2Mg, and YAu2In and their quaternary compounds (solid solutions) Y(Pd0.5Ag0.5)2Mg, Y(Pd0.5Ag0.5)2In, Y(Pd0.5Au0.5)2Mg, Y(Pd0.5Au0.5)2In, Y(Ag0.5Au0.5)2Mg and Y(Ag0.5Au0.5)2In were synthesized from the elements in sealed niobium ampoules in a high-frequency furnace or by arc-melting, respectively. All compounds crystallize with the cubic MnCu2Al type structure (Heusler phase), space group Fm3̅m. The structure of Y(Ag0.39Au0.61)2Mg was refined from single crystal X-ray diffractometer data: a = 689.97(5) pm, wR2 = 0.0619, 52 F2 values, 6 parameters. Magnetic susceptibility measurements show Pauli paramagnetic behavior for all samples. The compounds were investigated by 25Mg, 89Y and 115In solid state MAS NMR spectroscopy. Large positive resonance shifts are observed for all nuclei. A review of the present data in the context of literature data on isotypic Heusler phases with Cd and Sn indicates that the 89Y shifts show a correlation with the electronegativity of the main group atoms (Mg, Cd, In, Sn). The solid solutions Y(Ag1−xTx)2Mg (x = 0.1, 0.25, 0.33, 0.5; T = Pd, Au) clearly show Vegard-like behavior concerning their lattice parameters, and their main group element resonance shifts arising from spin and orbital contributions are close to the interpolated values of the corresponding end-member compounds. [ABSTRACT FROM AUTHOR]

As a member of RFeO 3 system (R = rare earth ions), the magnetic and optical properties of hexagonal yttrium ferrite (YFeO 3 ) have been rarely investigated. On the other hand, a mechanical route for synthesis of this orthoferrite ceramic has not been reported yet. The aim of the present work is to synthesize YFeO 3 via high energy ball milling aided by the sintering process. Photocatalytic behavior along with magnetic and absorption properties of YFeO 3 were also investigated. Besides, its potential of colossal dielectric constant was discussed in this research. X-Ray diffraction analysis (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetry (TG), differential thermal analysis (DTA), X-ray photoemission spectroscopy (XPS), ultraviolet–visible spectroscopy (UV–Vis) and Image-J software were utilized for data analysis. According to the obtained results, YFeO 3 can be regarded a visible light-driven photocatalyst, a semiconductor with a narrow bandgap, a weak ferromagnetic material, and a ceramic without a colossal dielectric constant. [ABSTRACT FROM AUTHOR]

A series of neodymium ions activated yttrium aluminate nanophosphors of various concentrations were synthesized by solution combustion method using oxalyl dihydrazide as a fuel. The crystal structure, optical energy gap, luminescent properties and Judd-Ofelt analysis were carried out. The use of the phosphor in revealing/enhancing the fingerprints quality was investigated in detail. The powder X-ray diffraction results confirmed the orthorhombic phase for the prepared samples. From diffuse reflectance spectra, estimated energy gap was found to be in range of 5.38–5.80 eV. The photoemission profile of YAlO 3 : Nd 3+ exhibit a blue emission upon 364 nm excitation. Further, the prepared materials were used for enhancing the quality of latent fingerprint technique. The present method was facile and robust for visualization of fingerprint with enhanced sensitivity, low glare light and high efficiency on various surfaces. The demonstrated results on facile detection of fingerprints virtually on any surfaces using YAlO 3 :Nd 3+ nanophosphors are versatile tool which hold great promise for practical applications on forensic sciences. [ABSTRACT FROM AUTHOR]

Yttrium and iron co-doped strontium titanium oxide Sr 0.92 Y 0.08 Ti 0.7 Fe 0.3 O 3− δ (SYTF) was investigated as an alternative anode material for solid oxide fuel cells (SOFCs). SYTF synthesized by the Pechini method exhibits excellent phase stability during the cell fabrication processes, SOFC operation, and good electrical conductivity (about 1.03 S/cm, porosity 30%) at 900 °C in methane. Because of the slow electrochemical reaction on the SYTF surface, the SYTF anode was modified by a SDC thin film coating on the anode pore wall surface, to increase the number of reaction sites and also accelerate the electrochemical reaction kinetics of the anode. The SDC-modified SYTF anode cell was stable for 300 hour using methane fuel. [ABSTRACT FROM AUTHOR]

A method of synthesis of single-phase europium-doped yttrium niobate powders without using additional fluxes is developed. Using this method, a series of samples with different europium concentrations are synthesized. The phase composition, grain size, and luminescent properties of the synthesized powders are studied. The optimal dopant concentration corresponding to the maximum luminescence intensity is determined. It is shown that the decay time of the most intense luminescence line of europium decreases with increasing europium concentration. Comparative analysis of the luminescent properties of calcium tungstate and the luminescent properties of a synthesized sample with the highest luminescence intensity is performed. [ABSTRACT FROM AUTHOR]

Monophasic and highly crystalline YCrO3 nanoparticles with an average grain size of 22 nm and a high surface area of 344 m2 g−1 have been prepared successfully by using a citrate precursor route for the first time. The two as obtained band gap values of 1.98 eV and 2.95 eV may be associated with the transition of chromium ions. The wedge shaped ferromagnetic loop with a saturation magnetization of 2.48 emu g−1, a remanent magnetization of 0.83 emu g−1 and a coercive field of 12.78 kOe as well as room temperature ferroelectricity with a remanent polarization of 0.009 μC cm−2, a saturation polarization of 0.026 μC cm−2 and a coercive field of −0.66 kV cm−1 establish the multiferroic characteristics of YCrO3 nanoparticles. In addition, humidity sensing characteristics with little repeatability sensor output and the response–recovery time were observed at a significance pace. [ABSTRACT FROM AUTHOR]

In this research, we have investigated the effects of three samples of carbon-base nanostructures (carbon nanoparticles, carbon nanotubes and silicon carbide nanoparticles) doping on the properties of Y 1 Ba 2 Cu 3 O 7− δ (YBCO) high temperature superconductor. The pure and doped YBCO samples were synthesized by sol–gel method and characterized by resistivity versus temperature (ρ– T ), current versus voltage ( I – V ), through X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis. The results confirmed that for all the samples, the orthorhombic phase of YBCO compound is formed. We found that the pinning energy and critical current density of samples increase by adding carbon nanostructures to YBCO compound. Also critical temperature is improved by adding carbon nanotubes to YBCO compound, while it does not change much for carbon and silicon carbide nanoparticles doped compounds. Furthermore, the samples were characterized by UV–vis spectroscopy in 300 K and the band gap of the samples was determined. We found that the carbon nanotubes doping decreases YBCO band gap in normal state from 1.90 eV to 1.68 eV, while carbon and SiC nanoparticles doping increases it to 2.20 and 3.37 eV respectively. [ABSTRACT FROM AUTHOR]

A series of Y 2.94 Al 5− m Ga m O 12 :0.06Ce 3+ (1≤ m ≤2.5) green phosphors were successfully synthesized by a solid-state reaction method. The microstructure, morphology, luminescence spectra and thermal stability of the phosphors were investigated. NaF flux can greatly promote the growth and crystallization of Y 2.94 Al 5− m Ga m O 12 :0.06Ce 3+ (1≤ m ≤2.5) phosphors. The luminescence properties of Y 2.94 Al 5− m Ga m O 12 :0.06Ce 3+ (1≤ m ≤2.5) green phosphors dramatically depend on the m value. When m ≤1.5, the phosphor shows strong luminescence and excellent thermal stability. At 150 °C, the luminescence intensity of the m =1.0 and m =1.5 samples still maintains 90.3% and 88.8% of that measured at 25 °C, respectively. The experimental results demonstrate that Y 2.94 Al 4 GaO 12 :0.06Ce 3+ and Y 2.94 Al 3.5 Ga 1.5 O 12 :0.06Ce 3+ are promising green phosphors, which have great potential for use not only in high color rendering index white LEDs but also in high-power white LEDs. [ABSTRACT FROM AUTHOR]

In this work single phase hexagonal YMnO 3 powders were prepared starting from Y(CH 3 COO) 3 · x H 2 O, Mn(CH 3 COO) 2 ·4H 2 O, KMnO 4 and KOH using methods of conventional (280 °C for 6 h) or microwave assisted hydrothermal synthesis (200 °C for 2 h) followed by calcination at 1200 °C for 2 h. According to FESEM analysis the calcined powders consisted of submicronic YMnO 3 particles, which were uniform in shape and size. Ceramic samples were obtained by sintering the as-synthesized powders at 1400 °C for 2 h. XRD analysis confirmed the presence of the single phase hexagonal YMnO 3 . SEM analysis showed a dense and homogeneous microstructure with typical inter- and intra-grain cracks. Magnetic measurements indicated ferrimagnetic properties that were explained by non-stoichiometry of the obtained compound and an excess of manganese that was confirmed by ICP analysis. [ABSTRACT FROM AUTHOR]

The exploration of new color-tunable materials for solid-state lighting based on InGaN semiconductors has attracted great attention. Herein a series of Ce 3+ , Tb 3+ and Ce 3+ /Tb 3+ co-doped Y 2 Si 3 O 3 N 4 phosphors have been developed. The intense green emission peaking at 543 nm was observed in the Y 2 Si 3 O 3 N 4 :Ce 3+ ,Tb 3+ phosphors. Energy transfer (ET) process from Ce 3+ to Tb 3+ was verified via the variations of the lifetime values of Ce 3+ , and the ET mechanism is ascribed to the dipole–dipole interaction. The ET critical distance has been calculated by the concentration quenching method. It is believed that the Ce 3+ /Tb 3+ -activated Y 2 Si 3 O 3 N 4 phosphors can serve as potential materials for near ultraviolet (n-UV) light emitting diode (LED). [ABSTRACT FROM AUTHOR]

Yttrium aluminum perovskite (YAP) is a promising high temperature ceramic material, known for its mechanical, structural and optical properties. YAP’s also known as an ideal host material for solid-state lasers and phosphors. In this work, Ce 3+ doped YAlO 3 phosphors were synthesized by solid state reaction method, which is very suitable technique for large scale production. A prepared phosphor was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Photoluminescence spectra and Thermoluminescence (TL) glow curve study. The starting reagents used for sample preparation are Y 2 O 3 , Al 2 O 3 and CeO 2, boric acid used as a flux. Ratio of Y:Al was 1:1 which shows perovskite structure confirmed by the X-ray diffraction (XRD) study. The entire prepared sample was studied by PL excitation and emission spectra. Prominent peak at 446 nm (blue emission) which shows broad emission spectra of photoluminescence. It proves that prepared phosphor can act as a single host for blue emission of light and can be used for display applications. Commission Internationale de I’Eclairage (CIE) techniques proves the blue emission of light ( x = .148, y = .117). TL glow curve analysis of prepared phosphor shows the prominent peak at 189 °C for the variable UV exposure time and high temperature peak shows the more stability and less fading in the prepared phosphor. Kinetic data of prepared phosphor were evaluated by peak shape method for variable UV exposure time (5–25 min). [ABSTRACT FROM AUTHOR]

Nanoscopic yttrium acetate fluorides Y(CH3COO)3−zFz and yttrium oxide fluorides YO(3−z)/2Fz were prepared with tunable Y/F molar ratios via the fluorolytic sol–gel route. All samples were characterized by X-ray diffraction, elemental analysis and thermal analysis. In addition, local structures of all samples were studied by 19F MAS, 19F–89Y CP MAS and 1H–89Y CP MAS NMR spectroscopy and the respective chemical shifts are given. For both classes of compounds, only the fluorination using one equivalent of F (z = 1) leads to defined, well crystalline matrices: yttrium acetate fluoride Y(CH3COO)2F and r-YOF. [ABSTRACT FROM AUTHOR]

Highly Li-ion conductive Y-doped garnet-type Li5+2xLa3Ta2-xYxO12 (0.05 ≤ x ≤ 0.75) were studied to understand the effects of yttrium- and lithium-doping on crystal structure, porosity, and Li-ion conductivity using 7Li MAS NMR, electrochemical ac impedance spectroscopy, and scanning electron microscopy (SEM), as well as ex situ and in situ powder X-ray diffraction (PXRD) to further explore the potential application of garnets in all-solid-state Li-ion batteries. Solid-state 7Li MAS NMR studies showed an increase in the Li-ion mobility as a function of Y- and Li-doping in Li5+2xLa3Ta2-xYxO12, which is consistent with the results from ac impedance spectroscopy. The SEM studies on sintered pellets indicated a systematic decrease in porosity and an increase in sinterability as the Y- and Li-doping levels increase in Li5+2xLa3Ta2-xYxO12. These results are consistent with the calculated porosity and densities using the Archimedes method. Using the variable-temperature in situ PXRD in the temperature range of 30-700 °C, a thermal expansion coefficient of 7.25 × 10-6 K-1 was observed for Li6La3Ta1.5Y0.5O12. To further explore the possibility of a new application for the Li-stuffed garnets, the stability of these materials in aqueous LiCl solution was also studied. A high degree of structural stability was observed in these materials upon 1 M LiCl treatment, making them suitable candidates for further studies as protective layers for lithium electrodes in aqueous lithium batteries. [ABSTRACT FROM AUTHOR]

Polycrystalline, cerium-doped yttrium oxyorthosilicate (Y 1.99 Ce 0.01 SiO 5 , YSO:Ce) scintillator materials have been synthesized and characterized. The samples have been prepared using a mixed-powder route with LiF and NaF additives. The final reaction products have been analyzed for phase purity by X-ray powder diffraction (XRD) and Raman spectroscopy. The concentration of the additives and the temperature of the thermal treatment have strongly effected the formation of the desired high-temperature (X2-YSO) phase. The best yield for X2-YSO has been obtained with the application of 18 mol% LiF at 1400 °C. Samples obtained in this way also showed the highest luminescence yield (intensity per irradiating photon), which was attributed to the effect of Li + on the formation of the X2-YSO phase. [ABSTRACT FROM AUTHOR]

With the aim of exploring the effect of particle size and different polymorphic structures on the luminescence behaviour of Eu3+ ions, all in a single compound, the YInO3:Eu3+ system was synthesized. Metastable C-type modification could be obtained in YInO3 nanopowders synthesized by gel combustion. The broadening in Raman modes has been related to both the particle size and the strain in the metastable C-type modification. The hexagonal polymorph of YInO3, with a layered structure, quite unlike the C-type modification, could be obtained by heating nanopowders to 1175 °C. Such a change in the structure, leading to different site symmetries for Eu3+ ions exhibited a tremendous bearing on its luminescence behaviour. Detailed steady state and time resolved luminescence studies revealed a highly distorted local site symmetry for the Y3+ ion in hexagonal YInO3. The nano C-type YInO3 exhibited greater asymmetry and a shorter lifetime as compared to the bulk C-type YInO3, attributable to more surface defects in the case of the former. The Judd–Ofelt parameters (Ω2 and Ω4) were determined which established a much higher asymmetry in the hexagonal modification. Along with higher lifetime, the hexagonal polymorph also possessed superior quantum yield values. In addition to providing a significant insight into the structure–luminescence correlation in this study, we propose an efficient red phosphor with a high red color purity. [ABSTRACT FROM AUTHOR]

Y 0.8 Ca 0.2 BaCo 4 O 7+ δ (YCBC4) was synthesized and investigated as a cathode for proton-conducting intermediate temperature solid oxide fuel cells (IT-SOFCs). Low thermal expansion coefficient (TEC) (~9.9×10 −6 K −1 ) can provide good thermal expansion compatibility with the standard SOFC electrolyte materials. Laboratory-sized quad-layer cells, consisting of NiO–BaZr 0.1 Ce 0.7 Y 0.2 O 3− δ (BZCY)/NiO–BZCY/BZCY/YCBC4, were fabricated by a one-step dry-pressing/co-firing process and tested from 550 to 700 °C with humidified hydrogen (~3% H 2 O) as the fuel and static air as the oxidant, respectively. An excellent power density of 472 mW cm −2 and a low electrode polarization resistance of 0.121 Ω cm 2 were obtained at 700 °C. Preliminary results demonstrated that the YCBC4 can be a promising cathode material for proton-conducting IT-SOFCs. [ABSTRACT FROM AUTHOR]

Low power plasma sprayed NiCrAlY/AlO coatings were fabricated with dried and crushed powders. Microstructure and phase composition were tested. The dielectric and microwave absorption properties of NiCrAlY/AlO coatings were also investigated in 8.2-12.4 GHz. Results showed that NiCrAlY presented in the form of numerous lamellas and a few particles. Both the real and imaginary part of permittivity increased with the increase of NiCrAlY content due to the enhancement of interfacial polarization and conductance loss. The reflection loss values of the coating filled with 20 wt% NiCrAlY could reach −10 dB in the frequency range of 8.7-10.8 GHz at a thickness of 1.7 mm. [ABSTRACT FROM AUTHOR]

Yttrium (Y)-doped BiOBr with different Y doping concentrations has been synthesized via solvothermal method in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C 16 mim]Br). Their structures, morphologies and optical properties were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic activities of the yttrium doped BiOBr samples were evaluated by the degradation of ciprofloxacin (CIP) and rhodamine B (RhB) under visible-light irradiation. The yttrium doped BiOBr exhibited enhanced photocatalytic activity for the degradation of the two types of pollutants, and the 5wt%Y-doped BiOBr showed the highest photocatalytic activity. The enhanced photocatalytic performance could be attributed to the reduced band gap and improved separation of electron–hole pairs. [ABSTRACT FROM AUTHOR]

Y 0.99− x Ca x PO 4 :0.01Dy 3+ (0≤ x ≤0.08) phosphors were synthesized by the homogeneous precipitation method. The obtained phosphors have pure tetragonal structure and spherical morphology with the particle size of about 2–3 μm. The excitation spectra present three strong excitation peaks at 325 nm, 351 nm and 365 nm in ultraviolet region owing to the f–f transition within 4f 9 electron configuration of Dy 3+ . The emission spectra show a strong blue emission (482 nm) and another weak yellow emission (572 nm) corresponding to the 4 F 9/2 → 6 H 15/2 transition and the 4 F 9/2 → 6 H 13/2 transition of Dy 3+ , respectively. The luminescence intensity of YPO 4 :0.01Dy 3+ is improved after partially substituting Ca 2+ for Y 3+ ; the emission intensity of Y 0.95 Ca 0.04 PO 4 :0.01Dy 3+ is about 174% higher than YPO 4 :0.01Dy 3+ . Besides, the color chromaticity coordinates of the as-synthesized phosphors are within a small range of x =0.307−0.319, y =0.331−0.334. [ABSTRACT FROM AUTHOR]

AC susceptibility and DC magnetization relaxation measurements have been performed for YBaCuO films containing BaZrO nanorods preferentially oriented along the c axis, with the external magnetic field perpendicular to the film surface. It was found that the effective vortex activation energy U supplied by the standard analysis of the frequency dependent AC magnetic response remains very high even in the vicinity of the irreversibility line indicated by the DC relaxation. We show that the large U values appearing in the AC signal are related to the pinning enhanced viscous drag and significant vortex velocities. [ABSTRACT FROM AUTHOR]

YBaCuO/1 wt% BSO composite thin films are grown by pulsed laser deposition. The films are irradiated with 100 KeV Ar ions at room temperature. X-ray diffraction and Raman techniques are used for analysis of structural disorder. The reduction in the intensity of the XRD peaks after irradiation gives a clue of modification occurring in the sample. Raman spectra shows the displacement of apical oxygen O(4) at 500 cm and defect induced peaks appear at 555 and 723 cm on irradiation. Field emission scanning electron microscopy (FESEM) analysis shows the agglomeration of BSO particles by damaging the surface of the film with increase in irradiation fluence. Fluctuation conductivity is analyzed within the framework of Aslamazov-Larkin and Lawrence-Doniach theories that fits well for 3D and 2D regimes. [ABSTRACT FROM AUTHOR]

Superconducting samples of type YNd BaCaCuO, with 0.00 ≤ x≤ 0.40, were prepared by the conventional solid-state reaction technique. The phase formation percentage, lattice parameters and orthorhombic distortion were calculated using X-ray powder diffraction (XRD) data. The surface morphology for these samples was examined using scanning electron microscope (SEM). All elemental contents for YNdBaCaCuO phase 0.00 ≤ x≤ 0.40, were estimated from the particle-induced X-ray emission (PIXE), and the results are in good agreement with the nominal elemental content. In addition, the oxygen content was determined using elastic Rutherford backscattering spectroscopy (RBS) technique at MeV proton beam. The electrical resistivity and transport critical current density, for all investigated samples, were measured by standard DC four-probe method. The superconducting transition temperature T and the transport critical current density J decreased by increasing the substitution content, and this suppression was discussed according to different reasons. [ABSTRACT FROM AUTHOR]

The evolution of the rate of flux creep along the major hysteresis envelopes in a YLuBaCaO sample synthesized by a modified melt powder melt growth (MPMG) method at 25 K has been investigated. Magnetic relaxation rates depend strongly on the prior magnetic history. Calculations based on the critical state model can reproduce quite well the experimental data for magnetization when we have chosen the field exponent n = 0.3 in critical current density, J( H) = J/( H− I), where I = H when 0 < H < H and $I_{\mathrm {M}} =H_{\mathrm {c}1}^{p+1} /H_{\mathrm {a}}^{p} $ when H ≥ H. Using the field-cooled magnetization M data as well as the comparison of experimental and calculated M- H hysteresis loop, we estimated H = 500 Oe, p = 0, and the penetration field H = 20 kOe. The apparent pinning energy was estimated as 62 meV for the remanent magnetization upon an excursion of 40 kOe. [ABSTRACT FROM AUTHOR]

Hierarchical YVO4 microspheres have been prepared via L-aspartic acid (L-Asp) assisted hydrothermal route. X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to characterize the crystalline phase and morphologies of the products. The SEM results from different reaction stages indicate that YVO4 microspheres are self-assembled by numerous nanowires with diameter of 30-50 nm. It is found that the amount of L-Asp and reaction time play crucial roles in the formation of hierarchical nanowires-assembled YVO4 microspheres. The photocatalytic properties of YVO4 were investigated by the decomposition of Rhodamine B (RhB) under UV light irradiation and exhibit good photocatalytic activities. [ABSTRACT FROM AUTHOR]

The new tert-butoxide yttrium complex [CH-1,2-NC(Bu)N(2,6-MeCH)}]YOBu(DME) containing the dianionic ansa-linked bis(amidinate) ligand with the rigid o-phenylene linker was synthesized by the metathesis of the chloride complex [CH-1,2-NC(Bu)N(2,6-MeCH)}]Y(THF)(μ-Cl)Li(THF) with potassium tert-butoxide and structurally characterized. The synthesized yttrium bis(amidinate) tert-butoxide complex exhibits a moderate catalytic activity in the polymerization of rac-lactide under mild conditions but makes it possible to carry out the process with high control and obtain atactic polylactide with a narrow molecular weight distribution ( M/ M = 1.55) and good correspondence of the calculated and experimentally determined M. It was found by X-ray diffraction analysis that the substitution in the coordination sphere of the ytterbium atom in complex [CH-1,2-{NC(Bu)N(2,6-MeCH)}]YbCl(DME) of a DME molecule for two THF molecules resulted in the migration of the chloride ligand from the apical to equatorial position. [ABSTRACT FROM AUTHOR]

The phase and crystal structure of Tm3+-Yb3+ codoped Y2WO6 phosphor synthesized via the solid state reaction method was analysed by X-ray diffraction. The surface morphology and impurity content of the phosphor were analysed by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. Upon excitation from a 980 nm diode laser, the developed phosphor shows three upconversion emission bands. Codoping with Yb3+ ions in the Y2WO6:Tm3+ phosphor significantly enhances the intensity of the frequency upconversion emission. The processes responsible for the UC emissions and their intensity variation upon codoping have been discussed with the help of pump power dependence, energy level diagrams and decay curve analysis. The intrinsic optical bistability and colour tunability are also reported for the developed phosphor. [ABSTRACT FROM AUTHOR]

A metallofullerene radical Y2@C81N was synthesized and characterized by ESR spectroscopy and ab initio calculations. It was revealed that the molecule adopts an unique azafullerene C81N cage derived from C82-C2v(9), and two yttrium ions are entrapped to form the endohedral structure. The unpaired electron of Y2@C81N radical was calculated to mainly localize on the Y2 dimer, leading to large hyperfine coupling constants of 75.7 and 69.8 G for the two yttrium nuclei. [ABSTRACT FROM AUTHOR]

Nonbonding layer-structured Y(IO3)3 was successfully prepared by a simple hydrothermal route and investigated as a novel photocatalyst for the first time. Its crystal structure was characterized by X-ray diffraction, high-resolution transmission electron microscopy, and scanning electron microscopy. The optical absorption edge and band gap of Y(IO3)3 have been determined by UV-vis diffuse reflectance spectra. Theoretical calculations of the electronic structure of Y(IO3)3 confirmed its direct optical transition property near the absorption edge region, and the orbital components of the conduction band and valence band (VB) were also analyzed. The photocatalytic performance of Y(IO3)3 was evaluated by photooxidative decomposition of rhodamine B under ultraviolet light irradiation. It demonstrated that Y(IO3)3 exhibits highly efficient photocatalytic activity, which is much better than those of commercial TiO2 (P25) and important UV photocatalysts BiOCl and BiIO4. The origin of the excellent photocatalytic performance of Y(IO3)3 was investigated by electron spin resonance and terephthalic acid photoluminescence techniques. The results revealed that the highly strong photooxidation ability that resulted from its very positive VB position should be responsible for the excellent photocatalytic performance. [ABSTRACT FROM AUTHOR]