Structural stability and optical properties of nanocrystalline zirconia

2010 ◽  
Vol 43 (4) ◽  
pp. 780-789 ◽  
Author(s):  
Sujit Manna ◽  
Tandra Ghoshal ◽  
A. K. Deb ◽  
S. K. De
Keyword(s):  
Optical Properties ◽  
Room Temperature ◽  
Temperature Stability ◽  
Band Gap Energy ◽  
Solvothermal Reaction ◽  
Cubic Phase ◽  
Visible Absorption ◽  
Size Growth ◽  
Crystallite Sizes ◽  
Hydrolysis Of

Nanoparticles of the cubic phase of zirconia (ZrO2) of size range 4.5–8.7 nm have been synthesized by alkaline hydrolysis of a zirconium salt followed by solvothermal reaction. Subsequently, the room-temperature stability of cubic ZrO2nanoparticles has been explored with the goal of understanding how crystal structure tends to transform into a structure of higher symmetry with decreasing crystallite size. The room-temperature-stable cubic phase in nanosized ZrO2has been observed to transform into the monoclinic phase at 873 K. The crystalline phases of ZrO2nanocrystals have been determined quantitatively by Rietveld refinement. Lattice constant and internal strain increase with decreasing particle size. Growth kinetics studies have established that cubic nanocrystals are more stable at smaller crystallite sizes. UV–visible absorption spectra show an absorption peak at 275 nm which indicates a lowering of the band gap energy. Photoluminescence spectra of zirconia nanoparticles show an emission peak at 305 nm at room temperature. The modification of the optical properties is explained on the basis of oxygen vacancies present within the samples.

Optical Properties of Nd Doped Lead Borotellurite Glass

2016 ◽  
Vol 846 ◽  
pp. 193-198 ◽  
Author(s):  
Azman Kasim ◽  
H. Azhan ◽  
S. Akmal Syamsyir ◽  
Mardhiah Abdullah ◽  
M.R.S. Nasuha
Keyword(s):  
Optical Properties ◽  
Room Temperature ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Rare Earth Ions ◽  
Band Gaps ◽  
Refractive Indices ◽  
Excitation Wavelength ◽  
Gap Energy ◽  
Trivalent Rare Earth

Many trivalent rare earth ions such as Er3+, Tm3+, Ho3+, Pr3+ and Nd3+ were doped as absorption and emission centers in glass hosts. In this work, lead borotellurite (PBT) glass doped with neodymium ion (Nd3+) has been prepared and characterized by mean of their optical properties. The UV-Vis measurement has been carried out in order to determine the optical band gap energy, reflective indices and the polarizability. Optical absorption spectra of the glass samples are recorded in the range 400–900 nm at room temperature From the result, there are six significant absorption peaks that corresponds to 525 nm, 584 nm, 683 nm, 747 nm, 805 nm and 878 nm wavelength have been observed with the most predominant peak to be used as excitation wavelength is found centered at 584 nm. The energy band gaps as well as the refractive indices were found to vary from 2.50eV to 2.59eV and from 1.89 to 1.96 with mol% of Nd content respectively. Meanwhile, the polarizability shows a similar trend of results to refractive indices as it varies from 5.56 x 10-24 cm3 to 5.63 x 10-24 cm3. These results will be discussed further in details.

Properties of ZnO Rod-Like Structures Due to Collapse of Bubble Implosion Process

2013 ◽  
Vol 756 ◽  
pp. 3-10
Author(s):  
Mahayatun Dayana Johan Ooi ◽  
Abdul Aziz Azlan ◽  
Mat Johar Abdullah
Keyword(s):  
Ultrasonic Irradiation ◽  
Room Temperature ◽  
Polycrystalline Structure ◽  
Visible Absorption ◽  
Irradiation Treatment ◽  
Sonication Treatment ◽  
Uv Visible ◽  
Hydrolysis Of ◽  
Zinc Iodide ◽  
Visible Absorption Spectroscopy

In this work, a chemically grown ZnO rod – like structure is produced via precipitation and post – sonication treatment based on the hydrolysis of zinc iodide (ZnI2) and diethanolamine (DEA). ZnO rod – like structures with aspect ratio of 3 to 4(diameter of 235 nm and 800 nm in length) was observed from the TEM micrograph.The as-synthesized ZnO wurtzite structure was compared to sample without ultrasonic irradiation treatment to study the effect of bubble implosion on the formation of the particle. In contrast to particles treated with ultrasonic irradiation, micron sized and agglomerated particles were observed in sample without the treatment. The mechanism related to acoustic cavitations and the formation of rod – like structure is explained. The XRD results show polycrystalline structure on both samples. The optical property of ZnO was evaluated using room temperature UV - Visible absorption spectroscopy. The result showed an absorption peak at 381 nm in wavelength.

Selenium Zinc Oxide (Se/ZnO) Nanoparticles: Synthesis, Characterization, and Photocatalytic Activity

2019 ◽  
Vol 74 (12) ◽  
pp. 1043-1056 ◽  
Author(s):  
Kamal K. Taha ◽  
Musadag M. Mustafa ◽  
Hasabo A. Mohamed Ahmed ◽  
Sarra Talab
Keyword(s):  
Zinc Oxide ◽  
Band Gap ◽  
Zinc Acetate Dihydrate ◽  
Band Gap Energy ◽  
Blue Dye ◽  
Zno Nps ◽  
Visible Absorption ◽  
X Ray ◽  
Uv Illumination ◽  
Crystallite Sizes

AbstractA facile synthesis of undoped and 2.0 % selenium-doped zinc oxide nanoparticles (NPs) was efficaciously accomplished through a mechanochemical route using zinc acetate dihydrate, oxalic acid, and Se powder in a solid state reaction. After calcination at 450 °C, the obtained nanostructures were probed by X-ray diffraction, where the acquired data revealed the pertinence of the wurtzite hexagonal ZnO for both undoped (ZnO) and doped (Se/ZnO) NPs and crystallite sizes of 30 and 24 nm for ZnO and Se/ZnO, respectively. The formation of the target NPs was confirmed by the scanning and transmission electron microscopy, energy-dispersive X-ray analysis, and the Fourier transformation infrared molecular vibrations data. The porosity investigations indicated 33.65 m2/g Brunauer–Emmett–Teller surface area, 197 Å pore diameter, and 0.172 cm3/g pore volume for the Se/ZnO NPs compared to lower values for the pristine ZnO. The band gap energies were 3.19 and 3.15 eV for ZnO and Se/ZnO as perceived from the Tauc plots of the UV-visible absorption measurements. The photodegradation of methylene blue dye under UV illumination was found to follow the pseudo–first-order kinetics with an enhanced performance by the doped samples as reflected by the higher (3.2 × 10−3 s−1) rate constant relative to the undoped sample (1.7 × 10−3 s−1). A photodegradation mechanism was suggested in the light of the band gap energy investigation. The obtained findings indicate the improvement of ZnO properties by doping with Se through a simplistic and inexpensive approach.

Regioisomeric synthesis of chlorin-e6 dimethyl esters and their optical properties

2018 ◽  
Vol 22 (12) ◽  
pp. 1039-1046 ◽  
Author(s):  
Yasunobu Nagano ◽  
Shin Ogasawara ◽  
Hitoshi Tamiaki
Keyword(s):  
Optical Properties ◽  
Absorption Spectra ◽  
Carboxy Group ◽  
Fluorescence Emission ◽  
Substitution Effect ◽  
Molecular Structures ◽  
Chlorin E6 ◽  
Visible Absorption ◽  
Methyl Esterification ◽  
Hydrolysis Of

Chlorin-[Formula: see text] dimethyl esters possessing a single carboxy group at the 13-, 151-, or 172-position were prepared by chemically modifying chlorophyll-[Formula: see text]. These three synthetic regioisomers were fully characterized by their mass, NMR, and visible absorption spectra. Their molecular structures were unambiguously identified by the specific 1H–[Formula: see text]C correlation at the 13-, 15-, and/or 17-substituents in their respective HMBC spectra. Methyl esterification of 13/151-COOH and hydrolysis of 13/151-COOMe affected small shifts of the Qy absorption and fluorescence emission maxima in a diluted CH2Cl2 solution, while no substitution effect of 172-COOH/Me was observed.

HIGH TEMPERATURE STABILITY OF OPTICAL PROPERTIES OF InAs QUANTUM DOTS REALIZED BY CONTROLLING OF QUANTUM DOTS ELECTRONIC SPECTRUM

2007 ◽  
Vol 06 (03n04) ◽  
pp. 283-286 ◽  
Author(s):  
N. V. KRYZHANOVSKAYA ◽  
A. G. GLADYSHEV ◽  
S. A. BLOKHIN ◽  
A. P. VASIL'EV ◽  
E. S. SEMENOVA ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
High Temperature ◽  
Room Temperature ◽  
Temperature Stability ◽  
High Energy ◽  
Energy Separation ◽  
High Temperature Stability ◽  
Carrier Distribution ◽  
Inas Quantum Dots

The optical properties of InAs /( Al ) GaAs quantum dots (QDs) overgrowth by thin AlAs / InAlAs layers are studied as a function of temperature from 10 to 500 K. The QDs emit at 1.27 μm at room temperature. It is shown that the QD energetic spectrum can be tuned by overgrowth of AlAs / InAlAs to provide high temperature stability of the QDs optical properties. Transport of carriers between neighboring QDs is absent, and the carrier distribution remains nonthermal up to room temperature. It is shown that suppression of the thermal escaping of the carriers from QDs is conditioned by high energy separation between ground and excited states, absence of wetting layer level, and increase of carrier localization energy in QDs in case of the Al 0.3 Ga 0.7 As matrix.

scholarly journals Investigating on Structural, Optical, Magnetic and Photocatalytic Activities of ZnS and Co2+: ZnS NPs Synthesized by Hydrothermal Process Under MeB Dye

2021 ◽  
Author(s):  
S. Upputuri ◽  
S. Lakshmanan ◽  
Ramalakshmi N ◽  
S. Arul Antony
Keyword(s):  
Room Temperature ◽  
Dopant Concentration ◽  
Hydrothermal Process ◽  
Average Crystallite Size ◽  
Band Gap Energy ◽  
Cubic Phase ◽  
Chemical Route ◽  
Photocatalytic Activities ◽  
Uv Visible ◽  
Electron Trapping Center

Abstract In present work, the structural, morphological, optical and photocatalytic activities of ZnS and Co2+: ZnS NPs were prepared through chemical route as hydrothermal process at room temperature. ZnS and Co2+: ZnS were characterized by using various techniques such as, XRD, SEM-EDX, TEM-SAED, UV-visible, PL and BET. The spherical-like morphology with the average crystallite size was found to be 8 to 15 nm. Among them results, it showed that the Co2+ atoms were incorporated into the ZnS lattice, forming cubic phase as the Co2+ dopant concentration increases from 0 to 2 %. The band gap energy of the ZnS and Co2+: ZnS increases from 3.5 to 4.10 eV, which enables stronger absorption of UV region. During catalytic process, Co2+ act as electron trapping center, which inhibits the recombination of the photo induced holes and electrons as showed higher degradation efficiency for MeB.

Optical Properties of Erbium Doped Tellurite Glasses

2016 ◽  
Vol 864 ◽  
pp. 37-41 ◽  
Author(s):  
Mukhayyarotin Niswati Rodliyatul Jauhariyah ◽  
Cari ◽  
Ahmad Marzuki
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Room Temperature ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Tellurite Glasses ◽  
Ion Content ◽  
Gap Energy ◽  
Erbium Doped ◽  
Angle Method

This paper presents the optical properties of erbium doped tellurite glasses with the composition of 55TeO2-2Bi2O3-35ZnO-5PbO-(3-x)Na2O-xEr2O3 where x = 0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mol% . Refractive index of the glasses was measured using Brewster’s angle method and their optical absorption spectra were measured in spectral range 200 – 1100 nm recorded at room temperature. The results show that the glass refractive index increases with the increase of Er3+ ion content in the glass and the optical band gap energy decreases with the increase of erbium content in the glass.

Modified Becke–Johnson (mBJ) exchange potential investigation of the optoelectronic properties of XThO3(X = Sa, Sr and Ba)

2019 ◽  
Vol 08 (01) ◽  
pp. 1850029
Author(s):  
Y. Benaissa Cherif ◽  
A. Labdelli ◽  
A. Boukortt ◽  
H. Abbassa ◽  
D. Aimouch ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Band Gap Energy ◽  
Exchange Potential ◽  
Cubic Phase ◽  
Full Potential ◽  
The Best Approximation ◽  
State Band ◽  
First Time

The electronic structure and optical properties of [Formula: see text], [Formula: see text] and [Formula: see text] in cubic perovskite structure are calculated using a density functional theory with full-potential linearized augmented plane wave (FP-LAPW) method. In this study, we have used the approximations LDA, GGA and mBJ, with mBJ the best approximation to get the band gap energy. This study is conducted through five stages: (1) We have started by optimizing the lattice parameters to find the basic state of each component (2) We have calculated electronic properties such as density of state, band structure, charge density (3) and based on the band structure we have also calculated the optical properties as dielectric function, absorption coefficient, refractive index, reflectivity and optical conductivity to discuss the different transitions and the new peaks. The mechanical (4) and thermodynamic (5) behavior was discussed for the first time for [Formula: see text] and [Formula: see text] in the cubic phase, in terms of elastic constants, and their related parameters, such as Young’s modulus, shear modulus and Poisson’s ratio. Our results show that [Formula: see text] has a stable ductile trait that makes it effective for high temperature electronic applications. As a result, the various new peaks in the wide UV region due to the transition of electrons confirm the application of [Formula: see text]([Formula: see text], Sr and Ba) in the field of optoelectronic devices.

scholarly journals The Effect of Structural Phase Transitions on Electronic and Optical Properties of CsPbI3 Pure Inorganic Perovskites

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1173
Author(s):  
Rahmad Syah ◽  
Afshin Davarpanah ◽  
Mahyuddin K. M. Nasution ◽  
Qamar Wali ◽  
Dadan Ramdan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Room Temperature ◽  
High Efficiency ◽  
Bond Angle ◽  
Structural Phase ◽  
Orthorhombic Phase ◽  
Band Gap Energy ◽  
Electronic And Optical Properties ◽  
Wide Range ◽  
Distortion Index

Hybrid inorganic perovskites (HIPs) have been developed in recent years as new high-efficiency semiconductors with a wide range of uses in various optoelectronic applications such as solar cells and light-emitting diodes (LEDs). In this work, we used a first-principles theoretical study to investigate the effects of phase transition on the electronic and optical properties of CsPbI3 pure inorganic perovskites. The results showed that at temperatures over 300 °C, the structure of CsPbI3 exhibits a cube phase (pm3m) with no tilt of PbI6 octahedra (distortion index = 0 and bond angle variance = 0). As the temperature decreases (approximately to room temperature), the PbI6 octahedra is tilted, and the distortion index and bond angle variance increase. Around room temperature, the CsPbI3 structure enters an orthorhombic phase with two tilts PbI6 octahedra. It was found that changing the halogens in all structures reduces the volume of PbI6 octahedra. The tilted PbI6 octahedra causes the distribution of interactions to vary drastically, which leads to a change in band gap energy. This is the main reason for the red and blue shifts in the absorption spectrum of CsPbI3. In general, it can be said that the origin of all changes in the structural, electronic, and optical properties of HIPs is the changes in the volume, orientation, and distortion index of PbI6 octahedra.

Synthesis and Optical Properties Study of ZnS Crystallitic Films

2014 ◽  
Vol 496-500 ◽  
pp. 301-306
Author(s):  
Zheng Liu ◽  
Si Wei Xie ◽  
Guo Cheng Han ◽  
Ying Zhi Zhou
Keyword(s):  
Optical Properties ◽  
Room Temperature ◽  
Band Gap Energy ◽  
Complexing Agent ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strong Luminescence ◽  
Strong Luminescence Band

This manuscript presents the synthesis and characterization of ZnS crystallitic films on ITO conducting glass by a simple hydrothermal method, based on sulfuration conversion from Zn nanocrystallines which are synthesized by pulse-plating technology. X-ray diffraction (XRD), scanning electron microscopy (SEM) and equipped with Oxford 7538 (EDS) analyzer techniques were used to characterize the Zn nanocrystallines and the novel ZnS crystallitic films. The results showed that ZnS crystallitic films were wurtzite, uniform and compact. Furthermore, the existence of Zn nanocrystallines and the complexing agent 5-sulfosalicylate influenced the microsopic morphology of ZnS crystallitic films. The optical properties, band gap energy and the size of nanocrystals were studied by UV-vis spectrophotometer measurements. A photoluminescence (PL) study of the ZnS at room temperature (300 K) indicates a strong luminescence band at energy 5.3 eV.

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