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A facile chemical route synthesis and characterization of CdSe/ZnO nanocomposite
No full textThe controlled synthesis of CdSe/ZnO-nanocomposite fabrication by facile chemical route has been successfully performed. Crystalline structure was examined by XRD patterns, while the morphology was investigated was carried out using typical electron microscopic investigations of SEM and HR-TEM equipped with electron dispersion spectroscopy (EDS) analogous to the detection of chemical elements in hybrid composite. The typical SEM image of fabricated CdSe/ZnO-nanomaterial and the grain size was found to 12 nm. The elemental composition of CdSe/ZnO-nanomaterial was analyzed by energy dispersive X-ray spectrometry (EDS). The HR-TEM images of CdSe/ZnO NPs confirm the agglomerated particles neck with their neighbors and form hexagonal shapes. The UV-visible absorption spectroscopy was used to analyze the optical properties. From UV absorption spectrum, a broad peak at 405 nm was observed. The photoluminescence (PL) spectrum was also used to determine the optical properties. The PL spectrum shows the maximum was slightly red-shifted to 625 nm. At various frequencies and at an ambient condition of temperatures, the dielectric studies such as dielectric constant, dielectric loss and AC conductivity properties were investigated. Furthermore, we have studied the current density-voltage of CdSe/ZnO-nanocomposite
Unexplored photoluminescence from bulk and mechanically exfoliated few layers of Bi2Te3
Get PDFWe report the exotic photoluminescence (PL) behaviour of 3D topological insulator Bi2Te3 single crystals grown by customized self-flux method and mechanically exfoliated few layers (18 +/- 2 nm)/thin flakes obtained by standard scotch tape method from as grown Bi2Te3 crystals. The experimental PL studies on bulk single crystal and mechanically exfoliated few layers of Bi2Te3 evidenced a broad red emission in the visible region from 600-690 nm upon 375 nm excitation wavelength corresponding to optical band gap of 2 eV. These findings are in good agreement with our theoretical results obtained using the ab initio density functional theory framework. Interestingly, the observed optical band gap is several times larger than the known electronic band gap of similar to 0.15 eV. The experimentally observed 2 eV optical band gap in the visible region for bulk as well as for mechanically exfoliated few layers Bi2Te3 single crystals clearly rules out the quantum confinement effects in the investigated samples which are well known in the 2D systems like MoS2, WS2, WSe2, and MoSe2 for 1-3 layers
Interfacial behavior of confined mesogens at smectic-C*-water boundary
No full textIn this paper, we have investigated the behavior of mesogens at smectic-C*-water interface confined in a liquid crystal (LC) cell with interfacial geometry. Polarized optical microscopy was used to probe the appearance of various smectic-C* domain patterns at water interface owing to the reorientation of mesogens. The undulated stripe domains observed at the air interface of smectic-C* meniscus vanished as the water entered into the smectic layers and focal conical domain patterns appeared at smectic-C*-water boundary. A spatially variable electro-optical switching of LC molecules was also observed outside the electrode area of the interfacial cell. The electrode region at the interface, as well as on the water side, was damaged upon application of an electric field of magnitude more than 150 kV/m. The change in dielectric parameters of mesogens was extensively studied at interface after evaporating the water. These studies give fundamental insights into smectic-C*-water interface and also will be helpful in fabricating better LC devices for electro-optical and sensing applications
Analysing Effect of Different Parameters on Performance of Dodecyl Benzene Sulphonic Acid Doped Polyaniline based Ammonia Gas Sensor
No full textThe paper demonstrates the development of Dodecyl benzene sulphonic acid (DBSA) doped polyaniline (PANI) nanoparticles based ammonia gas sensor. DBSA doped PANI nanoparticles have been synthesized by chemical oxidative polymerization of aniline monomer in the presence of DBSA. The UV-Visible spectroscopy and X-ray diffraction measurements are used to confirm the formation of PANI and its doping by DBSA, whereas SEM images are used to see the formation of nanoparticles of PANT. The chloroform dispersion of synthesized PANI-DBSA was spin coated over prefabricated interdigitated Pt patterned glass substrate to realize porous gas sensing active layer. The sensor displays good response at 100 ppm ammonia concentration and can repeatedly detect ammonia with relative response of 5.5. Besides, this sensor development, an analysis of sensor performance against temperature variations is done to check thermal stability of the sensor. Effect of thin film thickness variations on relative response of the sensor is also analyzed. The experiments have been carried out at different concentrations which show that when concentration increases relative response and recovery time increase and response time decreases
An emerging nanostructured molybdenum trioxide based biocompatible sensor platform for breast cancer biomarker detection
No full textWe report results of the studies relating to the development of the emerging nanostructured molybdenum trioxide (nMoO(3))-based biocompatible label-free biosensing platform for breast cancer detection. The structural and morphological studies of the synthesized nMoO(3) nano-rods were investigated by XRD, SEM, X-ray photoelectron spectroscopic. and TEM techniques. This biocompatible one-dimensional (1D) nMoO(3)-based biosensing platform exhibited high sensitivity (0.904 mu AmUng/cm(2)). wide linear detection range (2.5-110 ng/mL), and a lower detection limit as 2.47 ng/mL toward human epidermal growth factor receptor-2 detection. The results obtained using this sensor platform on serum samples of breast cancer patients were validated using ELISA
A simple method to estimate the loading effects of Al/Si on the characteristic impedance of multilayer microstrip line
Get PDFThe present study aims to experimentally determine the microwave transmission and reflection properties of aluminum thin film grown on silicon using sputtering. A simple microstrip line based structure has been used for the microwave characterization in the frequency range 10 MHz to 26.5 GHz. Complex S-parameter measurements reveal only small differences on silicon loading and aluminum/silicon loading in comparison to the microstrip line. The characteristic impedance (Z) of the microstrip line loaded with silicon and with aluminum/silicon have been obtained corresponding to the length of the loadings using two port microwave analysis. Comparison of loaded microstrip line with no loading shows large changes in the real part well as imaginary part of the characteristic impedance in the frequency range less than 10 GHz. Percentage changes in the real (Z) and imaginary (Z) have been found as +/- 40% and +/- 10% in average, respectively, for silicon loading in comparison to the no loading case, whereas these changes have been found to be below +/- 5% for aluminium/silicon loading, thus these smaller changes suggest the similar responses for aluminium/silicon loading and no loading. The results reveal that the propagation can be restored with the application of aluminum with any semiconductor or dielectric as loading on the microstrip line, which shows its potential to be explored for making an individual microwave component
Zinc-Supported Multiwalled Carbon Nanotube Nanocomposite: A Synergism to Micronutrient Release and a Smart Distributor To Promote the Growth of Onion Seeds in Arid Conditions
No full textIn the current scenario, nanotechnological applications in the agriculture sector showing potential impacts on the improvement of plant growth in terms of protection and safety are at a very nascent stage. The present study deals with the synergistic role of zinc (Zn) and multiwalled carbon nanotubes (MWCNTs) synthesized as a zinc oxide (ZnO)/MWCNT nanocomposite, a prospective applicant to modulate the micronutrient supply and enhance the growth of onion seeds, thereby replacing harmful, unsafe chemical fertilizers. To the best of our knowledge, this is the first report wherein MWCNTs have been envisaged as a micronutrient distributor and a nutrient stabilizer enhancing the growth of onion plant under arid conditions. The growth trend of onion seeds was evaluated in an aqueous medium with varied concentrations of (i) MWCNTs, (ii) zinc oxide nanoparticles, and (iii) ZnO/MWCNT nanocomposites. ZnO/MWCNT nanocomposites with 15 mu g/mL concentration displayed the best seedling growth with the maximum number of cells in telophase. A significant growth trend with increased concentration of ZnO/MWCNTs displayed no negative impact on plant growth in contrast to that with the use of MWCNTs. The synergistic impact of Zn nanoparticles and MWCNTs in ZnO/MWCNT nanocomposites on the rate of germination was explained via a mechanism supported by scanning transmission electron microscopy
Structural, morphological, photoluminescence and electrical characterization of aluminium doped ZnO phosphors for solar cell applications
No full textWe report synthesis of highly luminescent and n-type conducting aluminium doped ZnO (AZO) phosphors using flux-free solidstate reaction technique followed by casting of thin films. The precursor powders were pelletized and fired at 1000 degrees C (AZO-1). In another typical case, 2-stage sequential firing has been adapted at 1000 degrees C followed by 1200 degrees C (AZO-2) in a flowing O2 gas environment. The stabilization (dwell) time has been fixed as 2 hours for all temperatures of firing in the furnace. After firing at 1200 degrees C, a new cubic phase (zinc aluminate) has been observed in the lattice along with the wurtzite ZnO phase. The microstructure analysis was substantiated with Rietveld refinement of the diffraction data of AZO-1 and AZO-2 samples. The photoluminescence (PL) measurements revealed that both AZO-1 and AZO-2 exhibited green (similar to 523 nm) PL under UV (375 nm) excitation, with emission intensity of AZO-1 comparatively higher than that of AZO-2 sample. Moreover, the measurement of electronic transport properties of the AZO-1 and AZO-2 samples exposed their n-type behavior, with slightly lower electrical resistivity of AZO-1 (4.7 x 10(-3)Omega-m) as compared to AZO-2 (3 x 10(-3)Omega-m) at 700 K temperature. The AZO samples have been used as target materials for transparent thin film deposition on quartz substrate, thus proving it to be ideal materials for solar cell applications
SIM Key Comparison of S-parameters SIM.EM.RF-K5b.CL
Get PDFThe first RF key comparison within the Inter-American Metrology System (SIM) Regional Metrology Organization has been carried out. The purpose of it was to establish the degree of equivalence of scattering parameters measurements of both 1-port and 2-port coaxial devices among national metrology institutes (NMIs) that belong to SIM region and in support of CIPM Mutual Recognition Agreement (MRA). The travelling standards were four devices with Type-N coaxial connectors and 50 Omega of characteristic impedance: a matched load, a mismatched load and two attenuators of 3 dB and 20 dB. Four SIM institutes participated in the comparison as well as NPLI
A strategy to design lanthanide doped dual-mode phosphor mediated spectral convertor for solar cell applications
No full textHerein, we demonstrate the synthesis of dual-mode Gd2O3:Eu3+, Er3+, Yb3+ phosphor by a facile high-temperature solid-state method as a spectral convertor for the enhancement of conversion efficiency of solar cell. The dual-mode Gd2O3:Eu3+, Er3+, Yb3+ phosphor has cubic crystal structure with space group Ia (3) over bar. The surface morphology of dual-mode Gd2O3:Eu3+, Er3+, Yb3+ phosphor has been investigated by scanning electron microscopy. The spectroscopic features of dual-mode Gd2O3:Eu3+, Er3+, Yb3+ phosphor have been examined by photoluminescence (PL) and time-resolved photoluminescence (TRPL). The dual-mode Gd2O3: Eu3+, Er3+, Yb3+ phosphor gives strong red emissions at 611 nm and 663 upon excitation wavelengths of 200-500 nm and 980 nm, respectively. The dual-mode Gd2O3:Eu3+, Er3+, Yb3+ phosphor has average lifetime similar to 598.7 mu s. Further, PL intensity distribution in dual-mode Gd2O3:Eu3+, Er3+, Yb3+ phosphor have been examined by PL confocal microscopy. The spatially resolved PL mapping results reveal that dual-mode Gd2O3:Eu3+, Er3+, Yb3+ phosphor has PL emission throughout the sample at excitation wavelengths of 375 nm and 980 nm, respectively. Hence, the obtained results suggest that dual-mode Gd2O3:Eu3+, Er3+, Yb3+ phosphor could be a promising luminescent material for spectral convertor to improve the efficiency of next generation silicon solar cell