scholarly journals The effect of annealing temperature on the structural, optical, and electrical properties of CdS films

2010 ◽  
Vol 25 (1) ◽  
pp. 189-196 ◽  
Author(s):  
Hulya Metin ◽  
Mehmet Ari ◽  
Selma Erat ◽  
Semra Durmuş ◽  
Mehmet Bozoklu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Phase Transformation ◽  
Electrical Properties ◽  
Electronic Transport ◽  
Annealing Temperature ◽  
Optical Band Gap ◽  
Urbach Energy ◽  
Band Gap Energy ◽  
Optical And Electrical Properties ◽  
Gap Energy

Cadmium sulfide (CdS) photocatalyst films were grown on glass by chemical bath deposition (pH 9.4, 70 °C) and then annealed in nitrogen from 423 K to 823 K in steps of 100 K. The XRD crystallite size increases in a sigmoidal manner from 60 nm to 100 nm while the optical band gap energy decreases from 2.42 eV to 2.28 eV. This trend is paralleled by the decreasing Urbach energy, but only up to 623 K, where it increases again. This is the temperature where the Cd effectively surpasses the phase transformation from cubic to hexagonal, and the activation energy for electronic transport drops by a factor of nearly two.

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.

Optical Properties of Eu3+-Doped Lithium Tellurite Glass

2015 ◽  
Vol 1107 ◽  
pp. 432-436 ◽  
Author(s):  
Siti Aishah Jupri ◽  
Md Rahim Sahar ◽  
Sib Krishna Ghoshal
Keyword(s):  
Band Gap ◽  
Tellurite Glass ◽  
Optical Band Gap ◽  
Urbach Energy ◽  
Glass Network ◽  
Band Gap Energy ◽  
Melt Quenching ◽  
Absorption Properties ◽  
Gap Energy ◽  
Controlled Doping

Improving the optical response of tellurite glasses via controlled doping of rare earth is the key issue in lasing materials. A series of glasses of the form (74.4-x)TeO2(4.3)Li2O(21.3)LiCl (x)Eu2O3 with 0.0 x 2.0 mol% are synthesized using melt-quenching technique and the influence of Eu2O3 content on their UV-Vis absorption properties are examined. The absorption spectra reveal two prominent peaks centered at 464 and 533 nm corresponding to 7F05D2 and 7F15D1 transitions, respectively. The optical band gap energy for direct and indirect transitions are found to be in the range of 3.294-3.173 eV and 3.067-2.971 eV, respectively. The decrease optical band gap energy with the increase of Eu2O3 contents is attributed to the generation of non-bridging oxygen (NBOs). The increase in Urbach energy from 0.226-0.308 eV with the increase of Eu2O3 contents signifies the variation in disorder and compactness of the glass network.

scholarly journals Effect of Stepwise Replacement of LiF by Bi2O3 and of Annealing on Optical Properties of LiF⋅B2O3 Glasses

ISRN Optics ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Susheel Arora ◽  
Virender Kundu ◽  
D. R. Goyal ◽  
A. S. Maan
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Optical Band Gap ◽  
Urbach Energy ◽  
Optical Characterization ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Different Temperatures ◽  
Quench Method

Bismuth fluoroborate glasses with compositions xBi2O3⋅(40-x)LiF⋅60  B2O3  (x=0,5,10,15,  and  20) are synthesized by melt-quench method. Optical characterization was carried out to examine variation of optical band gap energy (Eg) and Urbach energy (EU) with respect to the concentration. It reflects the effect of stepwise replacement of non-oxide and less polarizable LiF by an oxide and more polarizable (Bi2O3) group on the optical properties of the samples. The value of Eg decreases with increase in concentration of Bi2O3. The samples were subjected to annealing at different temperatures (300°C, 350°C, and 400°C), and the effect of annealing on the optical properties of various samples was again studied. Annealing affects remarkably the values of Eg and EU in the samples with x=0.

Stability Investigation in the Optical Properties of Thermally Evaporated Ge5Se95-x Znx Thin Films

2015 ◽  
Vol 7 (3) ◽  
pp. 1923-1930
Author(s):  
Austine Amukayia Mulama ◽  
Julius Mwakondo Mwabora ◽  
Andrew Odhiambo Oduor ◽  
Cosmas Mulwa Muiva ◽  
Boniface Muthoka ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
Optical Transition ◽  
Bulk Material ◽  
Band Gap Energy ◽  
Optical Absorbance ◽  
Gap Energy ◽  
Constituent Elements

 Selenium-based chalcogenides are useful in telecommunication devices like infrared optics and threshold switching devices. The investigated system of Ge5Se95-xZnx (0.0 ≤ x ≤ 4 at.%) has been prepared from high purity constituent elements. Thin films from the bulk material were deposited by vacuum thermal evaporation. Optical absorbance measurements have been performed on the as-deposited thin films using transmission spectra. The allowed optical transition was found to be indirect and the corresponding band gap energy determined. The variation of optical band gap energy with the average coordination number has also been investigated based on the chemical bonding between the constituents and the rigidity behaviour of the system’s network.

Sol-gel growth of Ni doped CdS on glass substrates: effect of spin coating speed and dopant concentration

2020 ◽  
Vol 10 ◽  
Author(s):  
Atefeh Nazari Setayesh ◽  
Hassan Sedghi
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Spin Coating ◽  
Optical Band Gap ◽  
Dopant Concentration ◽  
Rotation Speed ◽  
Sol Gel ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Glass Substrates

Background: In this work, CdS thin films were synthesized by sol-gel method (spin coating technique) on glass substrates to investigate the optical behavior of the film. Methods: Different substrate spin coating speeds of 2400, 3000, 3600 rpm and different Ni dopant concentrations of 0 wt.%, 2.5 wt.%, 5 wt.%) were investigated. The optical properties of thin films such as refraction index, extinction coefficient, dielectric constant and optical band gap energy of the layers were discussed using spectroscopic ellipsometry method in the wavelength range of 300 to 900 nm. Results: It can be deduced that substrate rotation speed and dopant concentration has influenced the optical properties of thin films. By decreasing rotation speed of the substrate which results in films with more thicknesses, more optical interferences were appeared in the results. Conclusion: The samples doped with Ni comparing to pure ones have had more optical band gap energy.

scholarly journals Polymer Thermal Treatment Production of Cerium Doped Willemite Nanoparticles: An Analysis of Structure, Energy Band Gap and Luminescence Properties

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1118
Author(s):  
Ibrahim Mustapha Alibe ◽  
Khamirul Amin Matori ◽  
Mohd Hafiz Mohd Zaid ◽  
Salisu Nasir ◽  
Ali Mustapha Alibe ◽  
...  
Keyword(s):  
Solid State ◽  
Thermal Treatment ◽  
Band Gap ◽  
Optical Band Gap ◽  
Dopant Concentration ◽  
Blue Emission ◽  
Green Emission ◽  
Band Gap Energy ◽  
Solid State Lighting ◽  
Gap Energy

The contemporary market needs for enhanced solid–state lighting devices has led to an increased demand for the production of willemite based phosphors using low-cost techniques. In this study, Ce3+ doped willemite nanoparticles were fabricated using polymer thermal treatment method. The special effects of the calcination temperatures and the dopant concentration on the structural and optical properties of the material were thoroughly studied. The XRD analysis of the samples treated at 900 °C revealed the development and or materialization of the willemite phase. The increase in the dopant concentration causes an expansion of the lattice owing to the replacement of larger Ce3+ ions for smaller Zn2+ ions. Based on the FESEM and TEM micrographs, the nanoparticles size increases with the increase in the cerium ions. The mean particles sizes were estimated to be 23.61 nm at 1 mol% to 34.02 nm at 5 mol% of the cerium dopant. The optical band gap energy of the doped samples formed at 900 °C decreased precisely by 0.21 eV (i.e., 5.21 to 5.00 eV). The PL analysis of the doped samples exhibits a strong emission at 400 nm which is ascribed to the transition of an electron from localized Ce2f state to the valence band of O2p. The energy level of the Ce3+ ions affects the willemite crystal lattice, thus causing a decrease in the intensity of the green emission at 530 nm and the blue emission at 485 nm. The wide optical band gap energy of the willemite produced is expected to pave the way for exciting innovations in solid–state lighting applications.

Phase transformation and heterojunction construction of bismuth oxyiodides by grinding-assistant calcination in the presence of thiourea and its photoactivity

2021 ◽  
Author(s):  
Zichen Shen ◽  
Huanzhen Liu ◽  
Xuemei Jia ◽  
Qiaofeng Han ◽  
Huiping Bi
Keyword(s):  
Phase Transformation ◽  
Band Gap ◽  
Layered Structure ◽  
Band Gap Energy ◽  
Gap Energy

Bismuth-rich oxyhalides are promising photocatalysts due to their special layered structure and adjustable band gap energy. In this work, a series of bismuth oxyiodides were fabricated by grinding-assistant calcining in...

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