Investigation of optical properties and local structure of Gd3+ doped nano-crystalline GeSe2

2017 ◽  
Vol 31 (11) ◽  
pp. 1750075
Author(s):  
Hanan Hassan Hantour
Keyword(s):  
Optical Band Gap ◽  
Intensity Increase ◽  
Broad Line ◽  
Nano Particle ◽  
Monoclinic Structure ◽  
Melt Quenching ◽  
Main Band ◽  
Low Intensity ◽  
Nano Crystalline ◽  
Main Emission Band

Pure and Gd-doped nano-crystalline GeSe2 were prepared by the melt-quenching technique. Structure analysis using Rietveld program suggests monoclinic structure for both virgin and doped samples with nano-particle size 41 nm for GeSe2 and 48 nm for Gd-doped sample. A wide optical band gap as estimated from absorbance measurements is 4.1 and 4.8 eV for pure and doped samples in accordance with the confinement effects. Raman spectra show two unresolved components at [Formula: see text]202 cm[Formula: see text] with broad line width. Also, well identified low intensity ([Formula: see text] [Formula: see text] 145 cm[Formula: see text]) and high intensity ([Formula: see text] [Formula: see text] 250 cm[Formula: see text]) bands are detected. For Gd-doped sample, the main band is shifted to lower energies and its full width at half maximum (FWHM) is reduced by [Formula: see text]50% accompanied by an intensity increase of about [Formula: see text]17 fold times. The photoluminescence analysis of the pure sample shows a main emission band at [Formula: see text]604 nm. This band is split into two separated bands with higher intensity. The detected emission bands at wavelength [Formula: see text]650 nm are assigned to transmission from 6G[Formula: see text] to the different 6P[Formula: see text] terms.

scholarly journals Investigations of BaFe0.5Nb0.5O3 nano powders prepared by a low temperature aqueous synthesis and resulting ceramics

2019 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Thermal Expansion ◽  
Low Temperature ◽  
Growth Process ◽  
Optical Band Gap ◽  
High Specific Surface Area ◽  
Crystallite Growth ◽  
Crystalline Powder ◽  
Aqueous Synthesis ◽  
Nano Crystalline ◽  
Naoh Solution

A facile method to prepare nanoscaled BaFe0.5Nb0.5O3 via synthesis in boiling NaOH solution is describedherein. The nano-crystalline powder has a high specific surface area of 55 m2 g−1 and a crystallite sizeof 15 nm. The as-prepared powder does not show any significant crystallite growth up to 700 ◦C. Theactivation energy of the crystallite growth process was calculated as 590 kJ mol−1. Dense ceramics can beobtained either after sintering at 1200 ◦C for 1 h or after two-step sintering at 1000 ◦C for 10 h. The averagegrain sizes of ceramic bodies can be tuned between 0.23 µm and 12 µm. The thermal expansion coefficientwas determined as 11.4(3)·10−6 K−1. The optical band gap varies between 2.90(5) and 2.63(3) eV. Magneticmeasurements gave a Néel temperature of 20 K. Depending on the sintering regime, the ceramic samplesreach permittivity values between 2800 and 137,000 at RT and 1 kHz.

Optical Properties of Silica Borotellurite Glass Doped with Manganese Oxide

2017 ◽  
Vol 268 ◽  
pp. 18-22 ◽  
Author(s):  
I. Zaitizila ◽  
Mohamed Kamari Halimah ◽  
Farah Diana Mohammad ◽  
Mohd Shah Nurisya
Keyword(s):  
Optical Properties ◽  
Manganese Oxide ◽  
Band Gap ◽  
Diffraction Pattern ◽  
Optical Band Gap ◽  
Urbach Energy ◽  
Molar Fraction ◽  
Chemical Formula ◽  
Melt Quenching ◽  
Amorphous Nature

Silica borotellurite glasses doped with manganese oxide with chemical formula {[(TeO2)0.7(B2O3)0.3­]0.8[SiO2]0.2}1-x{MnO2}x (where x = 0.0, 0.01, 0.02, 0.03, 0.04 and 0.05 molar fraction) were fabricated. Silica were extracted from the burning process of rice husk. Glass samples were prepared by using the melt-quenching technique. The FTIR spectra showed that the addition of MnO₂ contributed to the transformation of TeO4 to TeO3. The diffraction pattern of XRD showed a broad hump which indicates the amorphous nature of the samples. The result for both optical band gap and Urbach energy showed decreasing trend as the concentration of manganese increased.

Upconversion Luminescence and Optical Studies of Nd3+ in Bismuth Borate Glasses

2013 ◽  
Vol 770 ◽  
pp. 153-156
Author(s):  
Onanong Chamlek ◽  
Pruittipol Limkitjaroenporn ◽  
Hong Joo Kim ◽  
Jakrapong Kaewkhao
Keyword(s):  
Energy Level ◽  
Band Gap ◽  
Glass Matrix ◽  
Optical Band Gap ◽  
Upconversion Luminescence ◽  
Emission Spectra ◽  
Borate Glasses ◽  
Optical Studies ◽  
Melt Quenching ◽  
Bismuth Borate

Neonymium doped bismuth borate glasses with composition 50Bi2O3 : (50-x)B2O3: xNd2O3 (where x = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) have been prepared by melt quenching technique. The optical and upconversion luminescence properties of glasses were investigated. The nine absorption peaks were observed, correspond with Nd3+ energy level in glass. The optical band gap decreased with increasing Nd2O3 concentration due to the increase of non-bridging oxygen (NBOs) in glass matrix. The upconversion luminescence emission spectra shows peak at 393 nm, assign to 4D3/24I11/2 transition.

scholarly journals Optical and Electrical Properties of Nd3+doped Na2O-ZnO-TeO2 Material

2021 ◽  
Vol 12 (6) ◽  
pp. 7927-7941
Keyword(s):  
Optical Band Gap ◽  
Large Range ◽  
Emission Spectra ◽  
Band Gap Energy ◽  
Optical And Electrical Properties ◽  
X Ray Diffraction ◽  
Melt Quenching ◽  
X Ray ◽  
Gap Energy ◽  
Dta And Tg

Neodymium-doped Na2O-ZnO-TeO2 (NZT) glasses were prepared by the conventional melt quenching technique. DTA and TG were used to confirm glass preparation through the glass transition temperature at 447°C for the glass system. The analysis of FTIR spectra and X-ray diffraction described the samples' nature as ionic and amorphous, respectively. The optical band gap energy was estimated using absorption spectra and found to be decreased from 2.63eV to 1.32 eV due to the increase of doping concentration. The intensity of the emission spectra was enhanced for the higher concentration of Nd3+ ions. The dielectric constant of the glass samples was found to be constant for the large range of frequency (3 kHz to 1 MHz). The variation of conductivity with the temperature of the samples had shown the Arrhenius mechanism of conduction.

scholarly journals Optical Properties of LiF–Li2O –WO3–B2O3  Glasses

2020 ◽  
pp. 344-348
Author(s):  
M. Srinivasa Reddy ◽  
S. Shankaraiah
Keyword(s):  
Optical Properties ◽  
Room Temperature ◽  
Optical Band Gap ◽  
Urbach Energy ◽  
Reflection Spectra ◽  
Composition Parameter ◽  
Melt Quenching ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
Optical Absorption And Reflection

<p>Glass with compositions  xLiF–(30−x)Li<sub>2</sub>O –10WO<sub>3</sub>–60B<sub>2</sub>O<sub>3</sub>  for 5 ≤ x ≤ 25 mol% have been prepared using the normal melt quenching technique. The optical absorption and reflection spectra were recorded at room temperature in the wavelength range 300-800 nm. From the absorption edge studies, the values of the optical band gap (E<sub>opt</sub>) and Urbach energy (ΔE) have been evaluated. The values of E<sub>opt</sub> and ΔE vary non-linearly with composition parameter, showing the mixed alkali effect.</p>

Effect of BaO on physical, optical and structural characteristics of ZnO– Al2O3–B2O3 glasses

2015 ◽  
Vol 11 (3) ◽  
pp. 3190-3197
Author(s):  
H. A. Saudi
Keyword(s):  
Optical Band Gap ◽  
Structural Characteristics ◽  
Band Gap Energy ◽  
Borate Glasses ◽  
Barium Borate ◽  
Melt Quenching ◽  
Structural Units ◽  
Gap Energy ◽  
Ir Studies ◽  
Absorption Studies

Zinc barium borate glasses with composition (65-x) B2O3-10Na2O-10Al2O3-10ZnO-5Li2O-xBaO with (0 ≤ x ≤40 % mol)have been prepared using melt quenching technique.The density, molar volume and the optical absorption studies revealed that the optical band gap energy (Eopt) and Urbachenergy increase with the increase of BaOcontent.This is mainly due to the increased polarization of theBa2+ ions and theenhanced formation of non-bridging oxygen (NBO). The IR studies indicate that these glasses are made up of [AlO6],[BO3],[BO4], and [AlO4] basic structural units.

Synthesis and Optical Property of MgMoO4 Crystals

2014 ◽  
Vol 975 ◽  
pp. 243-247 ◽  
Author(s):  
Camila Soares Xavier ◽  
Ana Paula de Moura ◽  
Elson Longo ◽  
José Arana Varela ◽  
Maria Aparecida Zaghete
Keyword(s):  
Mixed Method ◽  
Room Temperature ◽  
Optical Band Gap ◽  
Monoclinic Structure ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
Pl Emission ◽  
Yellow Region

In this work, we report on the synthesis of MgMoO4 crystals by oxide mixed method. The powder was calcined at 1100 °C for 4h and analyzed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Field emission gun scanning electron microscopy (FEG-SEM), Ultraviolet-visible (UV-vis) absorption spectroscopy and Photoluminescence (PL) measurement. XRD analyses revealed that the MgMoO4 powders crystallize in a monoclinic structure and are free secondary phases. UVvis technique was employed to determine the optical band gap of this material. MgMoO4 crystals exhibit an intense PL emission at room temperature with maximum peak at 579 nm (yellow region) when excited by 350 nm wavelength at room temperature.

Optical Properties of [(TeO2)0.7 (B2O3)0.3]1-x (Bi2O3)x Glass System

2015 ◽  
Vol 1107 ◽  
pp. 426-431 ◽  
Author(s):  
Azuraida Amat ◽  
Mohamed Kamari Halimah ◽  
Nurazlin Ahmad
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Optical Band Gap ◽  
Urbach Energy ◽  
Glass Composition ◽  
Melt Quenching ◽  
Quenching Temperature ◽  
Glass Forming ◽  
Refractive Index Increase ◽  
Quenching Method

Ternary tellurite based glasses [(TeO2)0.7 (B2O3)0.3]1-x (Bi2O3)x was prepared by melt quenching method with suitable melting and quenching temperature. A series of glasses were selected from 0.05 to 0.30 mol % and its glass-forming region was determined. The density, molar volume and refractive index increase when bismuth ions Bi3+ increase, this is due to the increased polarization of the ions Bi3+ and the enhanced formation of non-bridging oxygen (NBO). The values of optical band gap, Eopt decreases when Bi2O3 content increases. Urbach energy for each composition was also calculated and was found to be dependent on the glass composition.

OPTICAL AND SPECTROSCOPIC STUDIES OF Fe2O3-Bi2O3-B2O3:V2O5 GLASSES

2013 ◽  
Vol 27 (28) ◽  
pp. 1350207
Author(s):  
SANJAY ◽  
N. KISHORE ◽  
A. AGARWAL ◽  
S. DAHIYA ◽  
INDER PAL ◽  
...  
Keyword(s):  
Optical Band Gap ◽  
Transition Metal Ions ◽  
Amorphous Solids ◽  
Spectroscopic Studies ◽  
Band Gap Energy ◽  
Melt Quenching ◽  
Gap Energy ◽  
Amorphous Nature ◽  
Urbach’S Energy ◽  
Xrd Patterns

The glasses of compositions x Fe 2 O 3⋅ (40 - x) Bi 2 O 3⋅60 B 2 O 3⋅2 V 2 O 5 have been prepared by the standard melt-quenching technique. Amorphous nature of these samples is ascertained by XRD patterns. The presence of BO 3 and BO 4 units is identified by IR spectra of glass samples. The absorption edge (λ cut-off ) shifts toward longer wavelengths with an increase in Fe 2 O 3 content in the glass matrix. The values of optical band gap energy for indirect allowed and forbidden transitions have been determined and it is found to decrease with increase in transition metal ions. The Urbach's energy is used to characterize the degree of disorder in amorphous solids.

scholarly journals Optical Transitions from Hexavalent Chromium in Lithium-Borate Glasses

2021 ◽  
Author(s):  
Dhia-Aldin Slibi ◽  
Moukhtar Hassan ◽  
Zakaria M. Abd El-Fattah ◽  
M. Atallah ◽  
M. A. El-Sherbiny ◽  
...  
Keyword(s):  
Optical Band Gap ◽  
Oxidation States ◽  
Resonance Spectroscopy ◽  
Borate Glasses ◽  
Optical Transitions ◽  
Melt Quenching ◽  
Glass Color ◽  
Spin Resonance ◽  
Optical Applications ◽  
Cr Doping

Abstract The melt-quenching technique was used to prepare a series of chromium-doped borate glasses with the composition xCr2O3 - (70-x) B2O3- 30 Li2O- (x = 0, 0.1, 0.2, 0.3 and 0.5 mol %). The low-doping level here employed allowed to unambiguously identify well-defined near-edge Cr6+ optical transitions, and to precisely determine the optical band gap of the borate glass host. Additional Cr3+ transitions were observed in the visible regime, rendering a strong modulation of the glass color, from colorless to dark greenish, with Cr content. Both Cr6+(after the charge transfer transformation into Cr5+) and Cr3+oxidation states and their variations with Cr doping were identified from electron spin resonance spectroscopy. All samples exhibit similar vibrational spectra dominated by BO3 and BO4 structural units, with the development of weak Cr6+ vibration with Cr doping. The present study provides structurally similar but optically active and tunable glass hosts suitable for various optical applications.

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