Layered Yttrium Hydroxide Research Articles

Luminescent Carrier, Tb3+-Doped Layered Yttrium Hydroxide, for Delivery Systems.

Layered rare-earth hydroxides (LRHs) with high anion exchangeability between the hydroxocation layers, where a large variety of organic anions can be sheltered, are employed to construct hybrid systems that slowly release active organic ingredients. More importantly, it is possible to endow LRHs with a photoluminescence capability by doping activator ions such as Ce3+, Eu3+, and Tb3+ into matrices. In the present work, we explored Tb3+-doped layered yttrium hydroxide Y1.80Tb0.20(OH)5Cl· nH2O (LYH:Tb) nanosheets as a luminescent carrier for sustained release of salicylic acid (2-hydroxybenzoic acid), an example of nonsteroidal anti-inflammatory drugs and antimicrobial agents. Salicylate (sal) was intercalated into the interlayer gallery of LYH:Tb via a direct ion-exchange reaction. An observed variation in basal spacing suggested that salicylate anions are arranged in an interdigitated bilayer manner in the interlayer space of LYH:Tb. As generally observed in organic/inorganic hybrid systems, the thermal and photostabilities of salicylate were significantly improved after intercalation compared to its free state. The release kinetics of salicylate from sal-LYH:Tb hybrids in a saline solution at pH = 7.4 showed a highly sustained release of salicylate. Among various examined mathematical models, the parabolic diffusion equation best described the cumulative salicylate release. In particular, the salicylate intercalation led to the characteristic 5D4 → 7F J ( J = 6, 5, and 4) green emission of Tb3+ by its sensitization followed by the energy transfer to sal-LYH:Tb, whereas typical blue emission of salicylate was recovered after its release from the interlayer gallery of the LYH:Tb carrier. This green/blue luminescence change behavior provides a useful technique for in situ monitoring of the delivery and release of salicylate at target sites. The sal-LYH:Tb hybrid, with antimicrobial properties, was readily dispersed into a biodegradable polymer, polyvinyl alcohol, to prepare a transparent, UV-shielding, and luminescent composite that is applicable as an antimicrobial polymer to retard or prevent microbial growth.

Fabrication of oriented oxide films from exfoliated yttrium hydroxide layers: Enhanced photoluminescence and unexplored behavior of energy transfer

Layered yttrium hydroxide (LYH) nanospalates doped with different activators (Tb3+ and/or Eu3+) were hydrothermally synthesized and then successfully delaminated into ultrathin nanosheets of down to 1–3 nm thickness via intercalation reactions and mechanical agitation. Using the LYH nanosheets, highly [001] oriented yttrium hydroxide films were constructed through spin-coating. Based on the quasi-topotactic transformation from yttrium hydroxide to cubic Y2O3, [111] oriented oxide films were achieved by proper annealing. For the highly oriented Y2O3:0.05Eu film, the enhanced photoluminescence was obtained compared with the powder form due to the higher exposure of (222) facets. Through adjusting the incorporated activation ions, films with different color were obtained, and energy transfer from Tb3+ to Eu3+ was observed for the alternatively multilayer film, although Eu3+ and Tb3+ were located in different layers.

Terbium‐Doped Layered Yttrium Hydroxide Nanocone: Controlled Synthesis, Structure Variations, Phase Conversion to Oxide/Oxysulfate Nanocone and Their Luminescence Properties

AbstractIt is demonstrated herein that a series of terbium ions (Tb3+)‐doped layered yttrium hydroxide (LYH:Tb) nanocones (NCs) intercalating dodecyl sulfate (C12H25SO4, DS) anions can be successfully synthesized in large quantities through a facile hydrothermal strategy. The DS anions in the interlayer gallery of LYH:Tb NCs can be readily modified with various anions (such as NO3 −, Cl−, and CH3COO−) through a convenient anion‐exchange procedure. The luminescent properties of LYH:Tb NCs are sensitively influenced by the dopant concentration and the interlayer anions. In particular, the original DS−‐intercalated form and the anion‐exchanged product can be topotactically converted into oxysulfates and oxides with original conical features through a calcination process at 750 °C for 2 h, respectively. Compared with Y2O3:Tb NCs, Y2O2SO4:Tb NCs exhibit efficient luminescent properties due to the stronger deformation of the crystal field. More interestingly, the conical structures also exhibit superior luminescent properties over the lamellar objects, originating from the extreme curvature and perturbation of crystal field, which are promising candidates for potential applications in optical and display devices.

A novel synthesis method of delafossite-type CuYO<sub>2</sub> using a layered yttrium hydroxide as an yttrium source

A novel synthesis method of delafossite-type CuYO<sub>2</sub> using a layered yttrium hydroxide as an yttrium source

Layered Yttrium Hydroxide l-Y(OH)3 Luminescent Adsorbent for Detection and Recovery of Phosphate from Water over a Wide pH Range

Layered yttrium hydroxide, l-Y(OH)3, has been explored as a representative member of the layered rare earth hydroxide family (l-RE(OH)3; RE = rare earths) for removal and recovery of phosphate from aqueous solution. Compared to the hexagonal form, h-Y(OH)3, which has a weakly positive surface charge only at low pH, the layered polymorph composed of hydroxocation layers exhibited a high point of zero charge (pHpzc ∼ 11) and significantly enhanced adsorptive ability for anions over a wide pH range. The Langmuir isotherm model and pseudo-second-order kinetic model were adopted to explain the phosphate adsorption on l-Y(OH)3. This new adsorbent revealed high capacity, efficiency, stability, selectivity, and reusability in adsorption of phosphate from a single electrolyte as well as natural waters containing competing anions. Essentially complete phosphate recovery from aqueous solutions at low phosphate concentrations (2.0 mg of P/L) was demonstrated with an adsorbent dosage of 0.025-0.5 g/L. The adsorption of phosphate was accompanied by an increase in the solution pH, suggesting a release of OH- ions during the adsorption reaction. In particular, when Ce3+ and Tb3+ were co-doped (l-Y(OH)3:Ce,Tb), phosphate adsorption led to the characteristic 5D4 → 7FJ (J = 6, 5, and 4) emissions of Tb3+ under commercial 312 nm UV irradiation. The photoluminescence of phosphate-adsorbed l-Y(OH)3:Ce,Tb provided evidence of the inner-sphere complexing mechanism involving the formation of Y(Ce,Tb)-O-P bonds through which the energy transfer can occur. The "luminescence-on" behavior of l-Y(OH)3:Ce,Tb by phosphate adsorption was employed to detect and recover phosphorus at low concentrations in deionized water, mineral water, tap water, and river water.

Phase-Tunable Synthesis of Monodisperse YPO4:Ln3+ (Ln = Ce, Eu, Tb) Micro/Nanocrystals via Topotactic Transformation Route with Multicolor Luminescence Properties

A novel aqueous-based and phase-selected synthetic strategy toward YPO4:Ln3+ (Ln = Ce, Eu, Tb) micro/nanocrystals was developed by selecting specific precursors whose structure topotactically matches with the target ones. It was found that layered yttrium hydroxide (LYH) induced the formation of hexagonal-phased h-YPO4·0.8H2O with the crystalline relationship of [001]LYH//[0001]h-YPO4·0.8H2O, while the amorphous Y(OH)CO3 favored the formation of tetragonal-phased t-YPO4. We also systematically investigated the influence of Na2CO3/NaH2PO4 feeding ratio on the evolutions of morphology and size of the h-YPO4·0.8H2O sample, and we also obtained a novel mesoporous nanostructure for t-YPO4 single crystalline with closed octahedron shape for the first time. Besides, the multicolor and phase-dependent luminescence properties of the as-obtained h-YPO4·0.8H2O and t-YPO4 micro/nanocrystals were also investigated in detail. Our work may provide some new guidance in synthesis of nanocrystals with target phase structure by rational selection of precursor with topotactic structural matching.

Synthesis of Y2O3:Bi3+,Yb3+ nanosheets from layered yttrium hydroxide precursor and their photoluminescence properties

Morphologies, photoluminescence properties, and photostability were characterized for Y2O3:Bi3+,Yb3+ fluorescent nanosheets prepared through calcining solvothermally synthesized layered yttrium hydroxide precursors.

Synthesis of Y2O3:Bi3+,Eu3+ nanosheets from layered yttrium hydroxide precursor and their photoluminescence properties

Morphologies, photoluminescence properties, and photostability were characterized for Y2O3:Bi3+,Eu3+ fluorescent nanosheets prepared through calcining solvothermally synthesized layered yttrium hydroxide precursors.

Fast synthesis of β-NaYF4:Ln3+(Ln = Yb/Er, Yb/Tm) upconversion nanocrystals via a topotactic transformation route

Monodisperse β-NaYF4:Ln3+ (Ln = Yb/Er, Yb/Tm) upconversion nanocrystals have been fast synthesized using layered yttrium hydroxide Y2(OH)5NO3·nH2O (LYH) via a topotactic transformation route bypassing the α-NaYF4 intermediate phase. It was found that the topotactic structural matching of [001]LYH//[0001]β-NaYF4 facilitated the direct formation of β-NaYF4, wherein the kinetic α-NaYF4 intermediate phase could be avoided at the initial reaction stage. Besides, the morphology could be effectively tuned by manipulating the NaF/Y(NO3)3 feeding ratio. In addition, the upconversion luminescence properties of the as-prepared β-NaYF4:15%Yb3+/2%Er3+ and β-NaYF4:15%Yb3+/1%Tm3+ were also systematically investigated.

Synthesis of a peroxo derivative of layered yttrium hydroxide

A stable yttrium peroxo compound containing 6.7% active (peroxide) oxygen is prepared by reacting layered yttrium hydroxonitrate Y4(OH)10(NO3)2 · xH2O with 12% or 87% aq. H2O2 at 0°C. The active oxygen in this compound is in the form of HO 2 - - and O 2 2- - groups as probed by IR and Raman spectroscopy. The thermolysis of the yttrium peroxo compound yields nanosized (6 nm) yttrium oxide.

Hybrid of Europium‐Doped Layered Yttrium Hydroxide and Organic Sensitizer – Effect of Solvent on Structure and Luminescence Behavior

AbstractThe organic sensitizer terephthalic acid and its anion terephthalate (TA) were introduced into the galleries of europium‐doped layered yttrium hydroxide (LYH:Eu). In contrast to using water as solvent, the use of formamide resulted in the introduction of more organic guests and markedly enhanced the Eu3+ luminescence. Formamide prevented water from entering the system, leading to an excess of terephthalic acid molecules, and more efficient coordination of the TA guest with the Eu3+ in the layers of the composite, all of which may have contributed to the enhanced Eu3+ luminescence.

Synthesis of Highly Luminescent and Anion-Exchangeable Cerium-Doped Layered Yttrium Hydroxides for Sensing and Photofunctional Applications

The discovery of new lanthanide properties in layered rare-earth hydroxides is tremendously important to developing novel materials with the advantages of both lanthanides and layered hydroxides. Herein, a polyethylenimine-assisted hydrothermal route for preparing Ce-doped layered yttrium hydroxide nanoplates (LYH:Ce NPs) is established, in which the Ce doping provides simultaneous control of the size and fluorescent properties. Typically, 10% Ce doping tailors the average particle size from 680 to 196 nm and induces bright blue luminescence with a quantum efficiency of over 10.0%. Owing to the much more efficient f–d Ce3+ transition, the LYH:Ce NPs show three orders of magnitude stronger photoluminescence than LYH:Eu and LYH:Tb NPs, and exhibit the properties required to fabricate switched “on/off” optical sensors by controlling the Ce3+ Ce4+ redox couple. Furthermore, by combining the merits of the luminescence of Ce3+ dopants and anion-exchange ability of an LYH host, the LYH:Ce NPs exhibit the properties necessary for photofunctional materials for photosensitized singlet oxygen production.

Intercalation of Ethylene Glycol into Yttrium Hydroxide Layered Materials

Intercalation of ethylene glycol into layered yttrium hydroxide containing nitrate counterions was accomplished by heating the reagents in a methanol solution of sodium methoxide under autogenous pressure at 413 K for 20 h. The resulting crystalline material had an expanded interlayer distance of 10.96 A, confirming the intercalation of an ethylene glycol derived species. Characterization of the material by FT-IR spectroscopy, thermogravimetric analysis, and the catalytic transesterification of tributyrin with methanol was consistent with direct bonding of ethylene glycolate anions (O(2)C(2)H(5)(-)) to the yttrium hydroxide layers, forming Y-O-C bonds. The layers of the material are proposed to be held together by H-bonding between the hydroxyls of grafted ethylene glycol molecules attached to adjacent layers. Glycerol can also be intercalated into yttrium hydroxide layered materials by a similar method.

Exfoliation and Stable Suspension of Layered Yttrium Hydroxide in Toluene

Exfoliation and Stable Suspension of Layered Yttrium Hydroxide in Toluene

Exfoliation and Stable Suspension of Layered Yttrium Hydroxide in Toluene.

Exfoliation and Stable Suspension of Layered Yttrium Hydroxide in Toluene.