Study on CdSe Nanoparticles Synthesized by Chemical Method

2013 ◽  
Vol 665 ◽  
pp. 267-282 ◽  
Author(s):  
M.P. Deshpande ◽  
Nitya Garg ◽  
Sandip V. Bhatt ◽  
Bindiya Soni ◽  
Sunil H. Chaki
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Cadmium Acetate ◽  
Cdse Nanoparticles ◽  
Effect Of Temperature ◽  
Longitudinal Optical Phonon ◽  
Cubic Phase ◽  
Phonon Modes ◽  
X Ray ◽  
Wide Range

CdSe is a II-VI group semiconducting material with optimum bulk band gap of 1.74eV. It is a promising material due to its wide range of technological applications in optoelectronics devices. CdSe nanoparticles have been synthesized at different temperatures starting from Room temperature to 80°C using appropriate precursor solutions containing Cadmium acetate, Triethanolamine (TEA), Ammonia and Sodium selenosulphate. The pH of Solution was around 10.50 ± 0.10 during synthesis. We confirmed the elemental analysis by Energy Dispersive X-ray Analysis (EDAX) and X-ray Photoelectron Spectroscopy (XPS) technique. X-Ray Diffraction (XRD) studies shows that the synthesized nanoparticles belonged to cubic phase with crystallite size lying between 2nm-4nm. The effect of temperature on particle size, lattice parameter, density of dislocation and strain were investigated. Blue shift of 103nm to125nm has been observed from optical absorption spectra and raman measurements performed at room temperature using He-Ne laser (632nm, 5mW) showed the presence of longitudinal optical phonon modes. Photoluminescence (PL) studies shows a shift of 30nm when compared with the bulk PL emission peak.

scholarly journals A Highly Sensitive Room Temperature CO2 Gas Sensor Based on SnO2-rGO Hybrid Composite

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 522
Author(s):  
Zhi Yan Lee ◽  
Huzein Fahmi bin Hawari ◽  
Gunawan Witjaksono bin Djaswadi ◽  
Kamarulzaman Kamarudin
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Gas Sensor ◽  
Photoelectron Spectroscopy ◽  
Hybrid Composite ◽  
Room Temperature ◽  
Co2 Gas ◽  
X Ray ◽  
Wide Range ◽  
Co2 Gas Sensor

A tin oxide (SnO2) and reduced graphene oxide (rGO) hybrid composite gas sensor for high-performance carbon dioxide (CO2) gas detection at room temperature was studied. Since it can be used independently from a heater, it emerges as a promising candidate for reducing the complexity of device circuitry, packaging size, and fabrication cost; furthermore, it favors integration into portable devices with a low energy density battery. In this study, SnO2-rGO was prepared via an in-situ chemical reduction route. Dedicated material characterization techniques including field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) were conducted. The gas sensor based on the synthesized hybrid composite was successfully tested over a wide range of carbon dioxide concentrations where it exhibited excellent response magnitudes, good linearity, and low detection limit. The synergistic effect can explain the obtained hybrid gas sensor’s prominent sensing properties between SnO2 and rGO that provide excellent charge transport capability and an abundance of sensing sites.

scholarly journals Studies of Optical, Dielectric, Ferroelectric, and Structural Phase Transitions in 0.9[KNbO3]-0.1 [BaNi1/2Nb1/2O3−δ]

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 35
Author(s):  
Blanca Yamile Rosas ◽  
Alvaro A. Instan ◽  
Karuna Kara Mishra ◽  
S. Nagabhusan Achary ◽  
Ram S. Katiyar
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Structural Phase ◽  
Cubic Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Wide Range

The compound 0.9[KNbO3]-0.1[(BaNi1/2Nb1/2O3−δ] (KBNNO), a robust eco-friendly (lead-free) ferroelectric perovskite, has diverse applications in electronic and photonic devices. In this work, we report the dielectric, ferroelectric, and structural phase transitions behavior in the KBNNO compound using dielectric, X-ray diffraction, and Raman studies at ambient and as a function of temperature. Analyses of X-ray diffraction (XRD) data at room temperature (rtp) revealed the orthorhombic phase (sp. Gr. Amm2) of the compound with a minor secondary NiO cubic phase (sp. Gr. Fm3m). A direct optical band gap Eg of 1.66 eV was estimated at rtp from the UV–Vis reflectance spectrum analysis. Observation of non-saturated electric polarization loops were attributed to leakage current effects pertaining to oxygen vacancies in the compound. Magnetization studies showed ferromagnetism at room temperature (300 K) in this material. XRD studies on KBNNO at elevated temperatures revealed orthorhombic-to-tetragonal and tetragonal-to-cubic phase transitions at 523 and 713 K, respectively. Temperature-dependent dielectric response, being leaky, did not reveal any phase transition. Electrical conductivity data as a function of temperature obeyed Jonscher power law and satisfied the correlated barrier-hopping model, indicating dominance of the hopping conduction mechanism. Temperature-dependent Raman spectroscopic studies over a wide range of temperature (82–673 K) inferred the rhombohedral-to-orthorhombic and orthorhombic-to-tetragonal phase transitions at ~260, and 533 K, respectively. Several Raman bands were found to disappear, while a few Raman modes such as at 225, 270, 289, and 831 cm−1 exhibited discontinuity across the phase transitions at ~260 and 533 K.

Temperature Dependent Raman Scattering and Dielectric Permittivity Measurements of Pb1−x Srx TiO3 Films

2003 ◽  
Vol 784 ◽  
Author(s):  
V. M. Naik ◽  
M. Smith ◽  
H. Dai ◽  
P. Talagala ◽  
R. Naik ◽  
...  
Keyword(s):  
Phase Transition ◽  
Dielectric Permittivity ◽  
Raman Spectra ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
X Ray ◽  
Permittivity Measurements

ABSTRACTPb1-x Srx TiO3 (x = 0 to 1.0) films of thickness ∼ 4 μ m have been prepared on sapphire and Pt substrates by metalorganic decomposition (MOD) method. X-ray diffraction results show that the films are polycrystalline with a perovskite tetragonal phase at room temperature for x < 0.5 and a cubic phase for x > 0.5. Room temperature Raman spectra show a systematic variation of lattice vibrational modes with x. The most notable changes in the Raman spectra with x are the decrease in the splitting of A1(3TO) and E(3TO) modes and the disappearance of E(3TO) mode at x ∼ 0.6. Although the x-ray diffraction peaks for films with x > 0.5 show a cubic phase at room temperature, the Raman spectra show the characteristic phonon modes of a tetragonal phase even at x = 0.7. The dielectric permittivity versus temperature measurements for films with x ≤ 0.7 show a broad dielectric anomaly corresponding to a diffuse ferroelectric to paraelectric phase transition. The phase transition temperature (Tc) values are consistently lower than the corresponding bulk ceramic alloys. Furthermore, Tc are also determined by monitoring the temperature dependence of the splitting between E(3TO) and A1(3TO) phonon modes in the Raman spectra of Pb1-x Srx TiO3 films for x ≤ 0.6. There has been good agreement between the two methods.

scholarly journals Two states of a light-sensitive membrane protein captured at room temperature using thin-film sample mounts

2022 ◽  
Vol 78 (1) ◽  
Author(s):  
Danny Axford ◽  
Peter J. Judge ◽  
Juan F. Bada Juarez ◽  
Tristan O. C. Kwan ◽  
James Birch ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Conformational Changes ◽  
Polymer Films ◽  
Diffraction Data ◽  
Room Temperature ◽  
Cubic Phase ◽  
Biological Macromolecules ◽  
X Ray ◽  
Wide Range

Room-temperature diffraction methods are highly desirable for dynamic studies of biological macromolecules, since they allow high-resolution structural data to be collected as proteins undergo conformational changes. For crystals grown in lipidic cubic phase (LCP), an extruder is commonly used to pass a stream of microcrystals through the X-ray beam; however, the sample quantities required for this method may be difficult to produce for many membrane proteins. A more sample-efficient environment was created using two layers of low X-ray transmittance polymer films to mount crystals of the archaerhodopsin-3 (AR3) photoreceptor and room-temperature diffraction data were acquired. By using transparent and opaque polymer films, two structures, one corresponding to the desensitized, dark-adapted (DA) state and the other to the ground or light-adapted (LA) state, were solved to better than 1.9 Å resolution. All of the key structural features of AR3 were resolved, including the retinal chromophore, which is present as the 13-cis isomer in the DA state and as the all-trans isomer in the LA state. The film-sandwich sample environment enables diffraction data to be recorded at room temperature in both illuminated and dark conditions, which more closely approximate those in vivo. This simple approach is applicable to a wide range of membrane proteins crystallized in LCP and light-sensitive samples in general at synchrotron and laboratory X-ray sources.

Solvothermal Preparation and Thermal Phase Change Behaviors of Nanosized Tetragonal-Phase Silver Selenide (Ag2Se)

2013 ◽  
Vol 850-851 ◽  
pp. 128-131 ◽  
Author(s):  
Jun Li Wang ◽  
Hui Feng ◽  
Wei Ling Fan
Keyword(s):  
Transition Temperature ◽  
Phase Change ◽  
Photoelectron Spectroscopy ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Variable Temperature ◽  
Cubic Phase ◽  
Silver Selenide ◽  
X Ray ◽  
Change Behaviors

Nanocrystalline silver selenide (Ag2Se) with an average diameter of 100 nm were prepared by a facile solvothermal method. X-ray energy dispersive (EDS) spectroscopy and X-ray photoelectron spectroscopy (XPS) studies confirmed that the products were pure Ag2Se. Room-temperature powder X-ray diffraction (XRD) measurements indicated that the as-prepared Ag2Se nanocrystals exhibit a metastable tetragonal polymorphic phase, rather than the common orthorhombic phase at room temperature. The variable-temperature XRD and differential scanning calorimetry (DSC) thermal analysis techniques were used to investigate the phase change behaviors of the tetragonal Ag2Se nanocrystals, and the results showed that the low-temperature tetragonal phase transforms to the high-temperature cubic phase at about 106 °C. This transition temperature is lower by ~30 °C than the orthorhombic-cubic transition temperature (133140 °C) previously reported for Ag2Se. Meanwhile, two exothermic peaks, loaded at 61 and 89 °C, respectively, were detected in the cooling DSC scan for the cubic to tetragonal phase transition, and the reason was discussed.

scholarly journals Synthesis of Magnetic Ferrocene-Containing Polymer with Photothermal Effects for Rapid Degradation of Methylene Blue

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 558
Author(s):  
Wenhui Zhu ◽  
Caiyun Zhang ◽  
Yali Chen ◽  
Qiliang Deng
Keyword(s):  
Methylene Blue ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Degradation Rate ◽  
Model Compound ◽  
Vibrating Sample Magnetometer ◽  
Simulated Sunlight ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir

Photothermal materials are attracting more and more attention. In this research, we synthesized a ferrocene-containing polymer with magnetism and photothermal properties. The resulting polymer was characterized by Fourier-transform infrared (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Its photo-thermocatalytic activity was investigated by choosing methylene blue (MB) as a model compound. The degradation percent of MB under an irradiated 808 nm laser reaches 99.5% within 15 min, and the degradation rate is 0.5517 min−1, which is 145 times more than that of room temperature degradation. Under irradiation with simulated sunlight, the degradation rate is 0.0092 min−1, which is approximately 2.5 times more than that of room temperature degradation. The present study may open up a feasible route to degrade organic pollutants.

ROOM TEMPERATURE PHOTOLUMINESCENCE OF POLYCRYSTALLINE SIC PREPARED FROM CARBON-SATURATED SI MELT

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1047-1051
Author(s):  
JIANPING MA ◽  
ZHIMING CHEN ◽  
GANG LU ◽  
MINGBIN YU ◽  
LIANMAO HANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Uv Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Composition And Structure ◽  
Light Excitation ◽  
Scanning Electron

Intense photoluminescence (PL) has been observed at room temperature from the polycrystalline SiC samples prepared from carbon-saturated Si melt at a temperature ranging from 1500 to 1650°C. Composition and structure of the samples have been confirmed by means of X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. PL measurements with 325 nm UV light excitation revealed that the room temperature PL spectrum of the samples consists of 3 luminescent bands, the peak energies of which are 2.38 eV, 2.77 eV and 3.06 eV, respectively. The 2.38 eV band is much stronger than the others. It is suggested that some extrinsic PL mechanisms associated with defect or interface states would be responsible to the intensive PL observed at room temperature.

Synthesis and Characterization of CdSe Nanoparticles with Cadmium Precursor Variation in Colloidal Synthesis

2014 ◽  
Vol 976 ◽  
pp. 52-58 ◽  
Author(s):  
Janeth Sarmiento Arellano ◽  
Enrique Rosendo ◽  
Román Romano ◽  
Gabriela Nieto ◽  
Tomás Díaz ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Ph Value ◽  
Sodium Tripolyphosphate ◽  
Compositional Analysis ◽  
Cadmium Acetate ◽  
Cdse Nanoparticles ◽  
Molar Concentration ◽  
Colloidal Synthesis ◽  
Cadmium Nitrate ◽  
X Ray

A comparative study of the synthesis of cadmium selenide (CdSe) nanoparticles (NPs) using different cadmium precursors such as, cadmium nitrate (Cd (NO3)2·4H2O), cadmium acetate ((CH3COO)2Cd·2H2O) and cadmium chloride (CdCl2·2.5H2O) is presented in this work. The method used to obtain the CdSe NPs was the colloidal synthesis at low temperature and atmospheric pressure. The Cd2+ ions were obtained in aqueous solution at room temperature, the surfactant used in the process was an aqueous solution of sodium hydroxide (NaOH), penta-sodium tripolyphosphate and H2O named commonly extran, which not only helps to stabilize the NPs, but also allows adjusting the pH of the solution. Se2- ions were obtained with sodium borohydride (NaBH4) as reductant at 75 oC. The by-products from the reaction were eliminated through a cleaning process with hydrochloric acid (HCl). Molar concentration of Cd:Se was varied from 3:1 to 1:3 and the pH value was varied between 8 and 11. The obtained samples were characterized by X-ray diffraction (XRD), it was seen that the obtained NPs present cubic centered face structure. The crystallite size from the powder was calculated using the Debye-Scherrer equation and was found between 3.3 nm and 5.6 nm, the variation in size depends on the molar concentration of cadmium and selenium. Morphological study was done using scanning electron microscopy (SEM) and compositional analysis was done by energy dispersive x-ray analysis (EDAX).

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