Doped Nanomaterials Research Articles

Structural studies and physical properties of novel Sm 3+-doped Sb 2Se 3 nanorods

Sm 3+ doped Sb 2Se 3 nanorods were synthesized by the co-reduction method at 180 °C and pH=12 for 48 h. Powder XRD patterns indicate that the Sm x Sb 2− x Se 3 crystals ( x=0.00–0.05) are isostructural with Sb 2Se 3. The cell parameters increase for Sm 3+ upon increasing the dopant content ( x). SEM images show that doping of Sm 3+ ions in the lattice of Sb 2Se 3 results in nanorods. High-resolution transmission electron microscopic (HRTEM) studies reveal that the Sm 0.05Sb 1.95Se 3 is oriented in the [1 0 −1] growth direction. UV–vis absorption reveals mainly electronic transitions of the Sm 3+ ions in doped nanomaterials. Emission spectra of doped materials, in addition to the characteristic red emission peaks of Sb 2Se 3, show other emission bands originating from f–f transitions of the Sm 3+ ions. The electrical conductance of Sm-doped Sb 2Se 3 is higher than undoped Sb 2Se 3 and increase with temperature.

Co-reduction synthesis of new Ln xSb 2− xS 3 (Ln: Nd 3+, Lu 3+, Ho 3+) nanomaterials and investigation of their physical properties

New Ln x Sb 2− x S 3 (Ln: Lu 3+, Ho 3+, Nd 3+)-based nanomaterials were synthesized by a co-reduction method. Powder XRD patterns indicate that the Ln x Sb 2− x S 3 crystals (Ln=Lu 3+, Ho 3+, x=0.00−0.1 and Ln=Nd 3+, x=0.00−0.08) are isostructural with Sb 2S 3. SEM images show that doping of Lu 3+ and Ho 3+ ions in the lattice of Sb 2S 3 results in nanorods while that in Nd 3+ leads to nanoflowers. UV–vis absorption and emission spectroscopy reveal mainly electronic transitions of the Ln 3+ ions in case of Ho 3+ and Nd 3+ doped nanomaterials. Emission spectra show intense transitions from excited to ground state of Ln 3+. Emission spectra of doped materials, in addition to the characteristic red emission peaks of Sb 2S 3, show other emission bands originating from f–f transitions of the Ho 3+ ions. TGA curves indicated that Sb 2S 3 has the highest thermal stability. The electrical conductance of Ln-doped Sb 2S 3 is higher than undoped Sb 2S 3, and increase with temperature.

Luminescence enhancement and quenching by codopant ions in lanthanide doped fluoridenanocrystals

Luminescence enhancement (LE) and quenching for lanthanide (Ln) doped nanocrystals is obtained by asecond Ln3 + ion doping method. Singly or doubly doped LaOF,LaF3 andNaYF4 nanocrystals are studied in detail under selective or two-color excitations. The underlyingreason for LE by codoping is explored, and a mechanism of the enhancementbased on the low local point symmetry effect of the matrix is proposed. It isfound that the modification of the local environment induced by dopant ionscan result in LE if the non-radiative relaxation probability can be ignored.The observations reported here should be useful for improving the quality ofLn3 + doped nanomaterials.

Correlation between Photocatalytic Efficacy and Electronic Band Structure in Hydrothermally Grown TiO2 Nanoparticles

The effects of electronic band structure, electron−hole recombination, and photocatalytic property of N- and/or Fe-doped TiO2 were systematically explored. Hydrothermal reaction was used to incorporate N and/or Fe into TiO2 nanoparticles. Structural analysis using Raman spectra, X-ray diffraction, and transmission electron microscope (TEM) indicates that hydrothermally grown TiO2 particles have anatase phase, and their average size is ∼10 nm. In addition, hydrothermal doping of N and/or Fe was found to significantly modify the electronic band structure. The photocatalytic performance of undoped and doped nanomaterials was examined under UV or visible light. N doping increased the photocatalytic efficacy of TiO2 under visible light by more than 2 times. In contrast, Fe-doped and N/Fe-codoped TiO2 show worse photocatalytic performance than pure TiO2 under both UV and visible light, in spite of their smaller band gaps. Fluorescence of terephthalic acid indicates that a change in the photocatalytic performanc...

Preparation of YVO 4:RE (RE=Yb 3+/Er 3+, Yb 3+/Tm 3+) nanoparticles via microemulsion-mediated hydrothermal method

A microemulsion-mediated hydrothermal method for synthesis of YVO 4:RE (RE=Yb 3+/Er 3+, Yb 3+/Tm 3+) nanoparticles by hydrothermal treatment of quaternary microemulsion medium consisting of Na 3VO 4/NaOH and RE(NO 3) 3 aqueous solution, surfactant cetyltrimethylammonium bromide (CTAB), cosurfactant n-hexanol and oil phase n-heptane was report. The confinement of microemulsion droplets acting as microreactors during the reaction process allows the formation of small size YVO 4:RE nanoparticles with relatively narrow size distribution and less aggregation. The structure, size and shape of YVO 4:RE nanoparticles were investigated by means of X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Compared with the conventional solid annealing diffusion method, the microemulsion-mediated hydrothermal method shows superiority in obtaining YVO 4:RE nanoparticles with controllable size, narrow size distribution and less aggregation. The microemulsion-mediated hydrothermal method may be potentially applicable for synthesis of other rare earth doped up-converting luminescence nanomaterials.

Chemical combustion synthesis and up-conversion properties of Er 3+ doped Yb 3Al 5O 12 powder

Er 3+ doped Yb 3Al 5O 12 powder has been prepared by chemical combustion and their structural and optical properties are determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), and up-conversion (UC) spectra. XRD and TEM show that the powder is composed of a highly crystalline garnet phase. When excited by a 980 nm laser diode, the Er 3+ doped Yb 3Al 5O 12 powder shows an intense red UC fluorescent band that can be assigned to the transition 4 F 9/2 → 4 I 15/2 of Er 3+ and a relatively weak green one corresponding to 2 H 11/2/ 4 S 3/2 → 4 I 15/2 in the UC spectra. The intensity ratio of the red to green emission is enhanced due to Li + incorporation. This can be attributed to the modification of local crystal fields around the rare-earth ions. Our results suggest that rare-earth doped alumina nanomaterials have potential applications in flat-panel displays and multicolor fluorescent labels.

Synthesis, characterization and thermal analysis of Fe-doped boehmite nanofibres and nanosheets

It is important that one should have knowledge of the thermal stability of synthesized nanomaterials. In this research, thermal analyses of both dynamic and controlled rate thermal analysis (CRTA) combined with infrared emission spectroscopy have been used to determine the thermal stability of iron-doped boehmite. Iron-doped boehmite nanofibres with varying iron contents have been prepared at low temperature using hydrothermal treatment in the presence of non-ionic poly (ethylene oxide) surfactant. The TEM images show that the resulting nanostructures are predominantly nanofibres when Fe doping is less than 5%; in contrast, nanosheets are the dominant for 10% Fe-doped boehmite. No nanofibre was observed in the case of 20% Fe-doped boehmite, instead, nanotubes, nanosheets and iron-rich nanoparticles were formed. Both dynamic thermal analysis and CRTA show that Fe-doped boehmite nanomaterials dehydroxylate at higher temperatures than pure boehmite nanofibres. In general, the higher the doped Fe %, the higher the dehydroxylation temperature. The dehydroxylation temperature indicated in the infrared emission spectroscopy of doped boehmite nanomaterials is in harmony with those in other thermal analysis studies.

One-dimensional and quasi-one-dimensional ZnO nanostructures prepared by spray-pyrolysis-assisted thermal evaporation

One-dimensional (1D) and quasi-1D ZnO nanostructures have been fabricated by a kind of new spray-pyrolysis-assisted thermal evaporation method. Pure ZnO powder serves as an evaporation source. Thus-obtained products have been characterized by X-ray diffraction (XRD) analysis, scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM). The room temperature photoluminescence spectrum of these ZnO nanostructures is presented. The results show that as-grown ZnO nanomaterials have a hexagonal wurtzite crystalline structure. Besides nanosaws, nanobelts and nanowires, complex ZnO nanotrees have also been observed in synthesized products. The study provides a new simple route to construct 1D and quasi-1D ZnO nanomaterials, which can probably be extended to fabricate other oxide nanomaterials with high melting point and doped oxide nanomaterials.

Experimental realization of suspended atomic chains composed of different atomic species

Research into nanostructured materials frequently relates to pure substances. This contrasts with industrial applications, where chemical doping or alloying is often used to enhance the electrical or mechanical properties of materials. However, the controlled preparation of doped nanomaterials has been much more difficult than expected because the increased surface-area-to-volume ratio can, for instance, lead to the expulsion of impurities (self-purification). For nanostructured alloys, the influence of growth methods and the atomic structure on self-purification is still open to investigation. Here, we explore, experimentally and with molecular dynamics simulations, to what extent alloying persists in the limit that a binary metal is mechanically stretched to a linear chain of atoms. Our results reveal a gradual evolution of the arrangement of the different atomic elements in the narrowest region of the chain, where impurities may be expelled to the surface or enclosed during elongation.

Doped Semiconductor Nanomaterials

The development and properties of doped nanomaterials including doped titanium dioxide, doped silicon, and doped cadmium telluride are reviewed, as well as their ultrafast dynamics. Doping nanomaterials provides a flexible way to tune to the properties of the materials while maintaining their high surface areas. The electronic, optical, photochemical, photoelectrochemical, photocatalytic and photoexcited relaxation properties can be tuned towards the desired direction by doping different elements. The materials can be engineered towards specific applications through careful selection of the dopants.

Nanophase unveils doped zinc oxides for antimicrobial and other applications

Nanophase Technologies Corp of Romeoville, IL, USA, has announced the commercial availability of doped zinc oxide nanomaterials. The dopants include aluminium, copper and silver at dopant levels ranging from several ppms to several percent. The doped nanomaterials are targeted at a wide variety of potential applications including antimicrobial agents (antifungal, antibacterial and antifouling) for plastics and other surfaces, opto-electronics and tailored UV absorption. This is a short news story only. Visit www.addcomp.com for the latest additives and compounding industry news

Creatinine determination in dried urine on filter paper

Low-dimensional antimony-doped tin oxide aggregated nanoparticles (ATO NPs; dia. ∼3.95 nm) were synthesized using hydrothermal method in alkaline phase. The optical, morphological, and structural properties of ATO NPs were characterized in details using FT-IR, UV/vis., FESEM, XEDS, XPS, TEM and XRD techniques. Glassy carbon electrode (GCE) was fabricated with a thin-layer of aggregated ATO NPs by conducting coating binders (5% ethanolic nafion) for the development of selective and sensitive enzyme-less creatine sensors. Electrochemical responses along with higher sensitivity, large-dynamic range and long-term stability towards creatine were performed by electrochemical I–V approach. The calibration curve was found linear over a wide linear dynamic range (LDR) of creatine concentration (0.1 nM ∼ 1.0 mM). From the gradient of the calibration plot, limit of detection (LOD) and sensitivity were calculated as 42.0 ± 0.1 pM and 276.3 μAmM−1cm−2 respectively. It is an organized route for the development of non-enzymatic creatine sensor based on ATO NPs embedded GCE using electrochemical reduction phenomena and significantly applied for the real sample analyses. As far as we know, this report is the maiden publication on highly sensitive creatine sensor based on the ATO NPs/Nafion/GCE. This method could be a pioneer development in creatine sensitive sensor development using ATO NPs in reliable I–V method for the important sensor applications with useful doped nanomaterials coupled nano-technological system.