ABSTRACT
Orthorhombic phase bismuth sulfide (Bi2S3) nanobelts were prepared via liquid-solid phase reaction method. Bi2S3 nanobelts were observed to be preferentially oriented along the (101) plane. Direct band gap (2.95 eV) and characteristic wavelength (λmax = 342 nm) were extracted through UV-visible spectroscopy. Specific surface area (9.8 m2/g) and pore size (2.5-120 nm) were evaluated through Brunauer-Emmett-Teller (BET) analysis. Relative humidity (RH) sensing properties were studied in the range of 11-97% RH at ambient conditions. The response of the sensor increases linearly with increase in RH. Fast response time (8-10 s) and recovery time (15 s) were observed. Reproducible and large response was also observed between 11 and 97% RH. Small hysteresis (<5%) and long-term stability during 30 days were confirmed. As a function of frequency, capacitance, alternating current conductivity, and electrical complex modulus in the frequency range of 20-2 MHz were studied at 11-97% RH. The sensing mechanism was also studied.
ABSTRACT
This communication reports on the novel work of creating a transistor channel based on functionalized single-walled carbon nanotubes (SWNTs) via electrostatic atomization deposition. The current method of drop-cast though convenient was unable to produce replicable transistor device due to its inherent inability in controlling the volume of liquid being drop-cast. Hence, this method of electrostatic atomization was introduced to consistently obtain a uniformly distributed SWNT channel resulting in a good transistor device.
ABSTRACT
Ce 3+-doped yttrium aluminum garnet nanophosphors with sizes near 30 and 250 nm have been synthesized by using chemical gelation and solvothermal methods, respectively. The size-dependent electron-longitudinal-optical-phonon coupling is investigated by fitting measured photoluminescence spectra within the framework of the Brownian oscillator model. Results show that the coupling strength is in a decreasing order from the bulk material to the nanophosphors of much smaller sizes.
ABSTRACT
Bio-compatible ZnO nanocrystals doped with Co, Cu and Ni cations, surface capped with two types of aminosilanes and titania are synthesized by a soft chemical process. Due to the small particle size (2-5 nm), surface functional groups and the high photoluminescence emissions at the UV and blue-violet wavelength ranges, bio-imaging on human osteosarcoma (Mg-63) cells and histiocytic lymphoma U-937 monocyte cells showed blue emission at the nucleus and bright turquoise emission at the cytoplasm simultaneously. This is the first report on dual-color bio-images labeled by one semiconductor nanocrystal colloidal solution. Bright green emission was detected on mung bean seedlings labeled by all the synthesized ZnO nanocrystals. Cytotoxicity tests showed that the aminosilanes capped nanoparticles are non-toxic. Quantum yields of the nanocrystals varied from 79% to 95%. The results showed the potential of the pure ZnO and Co-doped ZnO nanocrystals for live imaging of both human cells and plant systems.
ABSTRACT
The experimental parameters that control the size and size distribution of dysprosium oxide nanoparticles synthesized by homogeneous precipitation technique have been systematically investigated. The particles were characterized with respect to their size, shape, and thermal decomposition behavior. It was found that the precipitated particles were spherical, uniform in size, and amorphous, which upon heating in air, decomposed into the oxide form with no change in morphology. The size and size distribution of the particles showed strong dependence on the metal cation concentration ([Dy3+]) and weak dependence on urea concentration and aging time. In addition, the presence of chlorine ions (Cl-) was found to have significant effect on the growth and agglomeration of the particles. Aggregation mechanism as the growth mechanism is offered to explain the effects of these synthesis parameters on the morphology, size, and size distribution of dysprosium oxide particles.
