scholarly journals Synthesis, Phase Transition, and Optical Studies of Ba2−xSrxZnWO6 (x = 1.00, 1.25, 1.50, 1.75, 2.00) Tungsten Double Perovskite Oxides

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 299
Author(s):  
Yousef A. Alsabah ◽  
Mohamad S. AlSalhi ◽  
Eltayeb M. Mustafa ◽  
Abdelrahman A. Elbadawi ◽  
Sandhanasamy Devanesan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Diffuse Reflectance ◽  
Broad Band ◽  
Emission Spectra ◽  
Double Perovskite ◽  
Band Gap Energy ◽  
Optical Studies ◽  
X Ray ◽  
Gap Energy ◽  
Visible Spectra

Ba2−xSrxZnWO6 double perovskite (DP) oxide compounds (x = 1, 1.25, 1.5, 1.75, 2) were successfully created by means of conventional solid-state techniques. The crystal structures of our series were studied using an X-ray diffractometer. The x = 1 compound has a cubic (Fm-3m) crystal structure, the 1 ≤ x ≤ 2 compounds have tetragonal (I4/m) symmetry, and the phase was transferred to monoclinic (P21/n) symmetry for the Sr2ZnWO6 (x = 2) compound. Scanning electron microscopy (SEM) was used to investigate the morphology of the series, showing that the samples had crystallized microstructures. Molecular bonds were investigated using Fourier transform infrared and Raman spectroscopies, which confirmed the double perovskite octahedral geometry for the samples in our series. Furthermore, the octahedral W–O6 anti-symmetric stretching mode was found to occur. The optical properties of the Ba2−xSrxZnWO6 series were studied using Ultraviolet–visible (UV–vis) diffuse reflectance and photoluminescence (PL) spectroscopies. The absorption edge of the samples appeared around the near-violet and visible spectra, between 336–360 nm. The band gap energy was investigated in two ways—using the absorption cutoff and Tauc plots—which increased from 3.52 to 3.7 eV with increasing substitution of Ba2+ by Sr2+. Furthermore, excitation and emission spectra were collected at room temperature. A broad band at 260–360 nm appeared in the PLE spectra for all samples, and the PL spectra of the samples had a band that spread from 320–450 nm.

Structural and Optical Properties of Commercial Microparticle Zinc Oxide

2020 ◽  
Vol 990 ◽  
pp. 302-305
Author(s):  
Razif Nordin ◽  
Nadia Latiff ◽  
Rizana Yusof ◽  
Wan Izhan Nawawi ◽  
M.Z. Salihin ◽  
...  
Keyword(s):  
Room Temperature ◽  
Band Gap Energy ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Xrd Pattern ◽  
X Ray ◽  
Commercial Grade ◽  
Irregular Shapes ◽  
Visible Spectra ◽  
Uv Visible

Commercial grade ZnO were sieved into particle size of 38 to 90 μm at room temperature. X-ray diffraction (XRD) pattern confirms the hexagonal wurzite structure of ZnO microparticles. Irregular shapes of ZnO microparticles were observed by scanning electron microscope (SEM). Fourier transform infrared spectra (FTIR) confirmed the presence of Zn-O band. In addition, Uv-visible spectra (UV-Vis) were empolyed to estimate the band gap energy of ZnO microparticles.

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 SYNTHESIS OF Fe2O3-MONTMORILLONITE AND ITS APPLICATION AS A PHOTOCATALYST FOR DEGRADATION OF CONGO RED DYE

2010 ◽  
Vol 5 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Karna Wijaya ◽  
Iqmal Tahir ◽  
Nanik Haryanti
Keyword(s):  
Congo Red ◽  
Diffuse Reflectance ◽  
Uv Light ◽  
Band Gap Energy ◽  
Comparison Result ◽  
X Ray ◽  
Gap Energy ◽  
Congo Red Dye ◽  
Uv Illumination ◽  
Red Dye

The preparation of Fe2O3-montmorillonite and it's application as a catalyst for congo red dye photodegradation has been carried out. Fe2O3-montmorillonite was prepared by mixing the iron complexes pillaring agent and montmorillonite. The product was calcined at 250 oC for 5 hours. Montmorillonite and calcined product was analyzed by X-ray diffractometry (X-RD), infrared spectrophotometry (FTIR), gas  sorption analyser, X-ray fluorescense (X-RF) and UV/Vis diffuse reflectance spektrophotometry (UV-DRS). Fe2O3-montmorilonite then was used as a catalyst on congo red dye photodegrdation by UV-illuminating a mixture of 50 mg Fe2O3-montmorillonite and 25 mL congo red 10­-4M at 365 nm at various illuminating times. Adsorption of congo red on Fe2O3-montmorillonite and montmorillonite was also performed as a comparison. Result of X-RD analysis showed that the 001 reflection of  Fe2O3-montmorillonite was not  detected that probably indicating the formation of house of card stucture and this result was supported also by the analysis result of distribution of pores and SEM photography result. Results of the XRF analysis showed that iron content increased  from 5.21 % (w/w) in montmorillonite to 25.12 % (w/w) in Fe2O3-montmorillonite. UV- DRS analysis showed the increament of band gap energy from 3.69 eV in the iron oxide bulk to 3.8 eV in Fe2O3-montmorillonite. Specific surface area of the montmorillonite also increased significantly from 69,71 m2/g to 126,49 m2/g and total pores volume increased from 50.70x10-3 mL/Å/g  to 107.89x10-3 mL/Å/g, respectively. Photodegradation of congo red using Fe2O3-montmorillonite caused the decreament of congo red concentration up to 90.22 %  on UV illumination for 60 minutes. Adsorption of congo red on Fe2O3-montmorillonite reached 84.4% and on  montmorillonite was 75.15 %.   Keywords: photodegradation, congo red, Fe2O3-montmorillonite, UV light

scholarly journals Immobilization of cobalt doped rutile TiO2 on carbon nanotubes walls for efficient photodegradation of 2,4-dichlorophenol under visible light

2019 ◽  
Author(s):  
Pejman Monazzam ◽  
azadeh ebrahimian pirbazari ◽  
Behnam Fakhari Kisomi ◽  
Ziba Khodaee
Keyword(s):  
Carbon Nanotubes ◽  
Visible Light ◽  
Band Gap ◽  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Band Gap Energy ◽  
Cobalt Doping ◽  
Average Pore ◽  
X Ray ◽  
Gap Energy

In this work, we focused on improvement of rutile-type TiO2 degradation efficiency by cobalt doping and decorating on carbon nanotubes walls (CNTs) (Co-TiO2/CNTs). X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), diffuse reflectance spectroscopy (DRS), and nitrogen physisorption were used to characterize the prepared samples. The XRD results indicated after cobalt doping, we obtained rutile phase as the major phase for cobalt containing samples. The band gap energy of the synthesized samples were calculated by Kubelka-Munk equation using diffuse reflectance spectra. The surface area of the samples was obtained by BET model and average pore diameter and pore volume of the samples were extracted from desorption branch of BJH model. The effectiveness of the samples was examined through degradation of 2,4-dichlorophenol (2,4-DCP) as a model of organic pollutants under visible light. We achieved 27% and 50% visible light degradation of 2,4-DCP in the presence of pure TiO2 and Co-TiO2/CNTs after 180 min irradiation, respectively. The high visible light activity of Co-TiO2/CNTs sample can be approved that the presence of cobalt and CNTs reduce the band gap energy and sensitize TiO2 surface to visible light respectively. The mechanism for degradation of 2,4-DCP by Co-TiO2/CNTs photocatalyst under visible light is proposed.

Growth and Characterization of a-plane In0.2Ga0.8N/ GaN hetrostructures on r-Sapphire

2014 ◽  
Vol 1736 ◽  
Author(s):  
Shruti Mukundan ◽  
Lokesh Mohan ◽  
Greeshma Chandan ◽  
Basanta Roul ◽  
S.B.Krupanidhi
Keyword(s):  
Sapphire Substrate ◽  
Room Temperature ◽  
Molecular Beam ◽  
Single Phase ◽  
Flux Ratio ◽  
Band Gap Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gap Energy

ABSTRACTNon-polar a-plane InGaN films were grown on a r-plane sapphire substrate by plasma assisted molecular beam epitaxy (PAMBE). The growth temperature and Indium flux were varied to optimize the desired composition of In0.23Ga0.77N on the (11-20) a-plane GaN epilayer grown on a (1-102) r-plane sapphire substrate. The structural, morphological and optical properties of the optimized composition have been studied. It was found that highly a-axis oriented InGaN epilayers with no phase separation can be grown at 540 °C with In/Ga flux ratio of 0.72. The composition of indium incorporation in single phase InGaN films was found to be 23% as estimated by high resolution X-ray diffraction. The room temperature band gap energy of single phase InGaN layers was determined by photoluminescence measurement and found to be around 2.56 eV.

Band-Gap Energy Dependence of Emission Spectra in Rare Earth-Doped Zn(1-x)CdxS Thin Film Electroluminescent Devices

1992 ◽  
Vol 31 (Part 1, No. 2A) ◽  
pp. 295-300 ◽  
Author(s):  
Noboru Miura ◽  
Takashi Sasaki ◽  
Hironaga Matsumoto ◽  
Ryotaro Nakano
Keyword(s):  
Thin Film ◽  
Rare Earth ◽  
Band Gap ◽  
Energy Dependence ◽  
Emission Spectra ◽  
Band Gap Energy ◽  
Electroluminescent Devices ◽  
Gap Energy ◽  
Rare Earth Doped

scholarly journals Use and misuse of the Kubelka-Munk function to obtain the band gap energy from diffuse reflectance measurements

2021 ◽  
pp. 114573
Author(s):  
Salmon Landi ◽  
Iran Rocha Segundo ◽  
Elisabete Freitas ◽  
Mikhail Vasilevskiy ◽  
Joaquim Carneiro ◽  
...  
Keyword(s):  
Band Gap ◽  
Diffuse Reflectance ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Munk Function ◽  
Reflectance Measurements

Photocatalytic Reduction of CO2 over CdxZn1-xS Photocatalysts

2012 ◽  
Vol 610-613 ◽  
pp. 319-322
Author(s):  
Xue Feng Bai ◽  
Xian Da Li
Keyword(s):  
Hexagonal Phase ◽  
Band Gap Energy ◽  
Photocatalytic Reduction ◽  
Surface Photovoltage ◽  
Mercury Lamp ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gap Energy ◽  
Surface Photovoltage Spectroscopy ◽  
Composite Photocatalysts

A series of CdxZn1-xS (x=0.1~0.9) composite photocatalysts were prepared by coprecipitation method. The above-prepared photocatalysts were characterized by X-ray diffraction (XRD), UV-Vis diffusive reflectance spectroscopy (DRS),surface photovoltage spectroscopy (SPS). It was shown from XRD that CdxZn1-xS solid solution semiconductors were of hexagonal phase in agreement with pure CdS. The DRS and SPS results showed that the band gap energy gradually reduced with the increasing of x value in CdxZn1-xS, and when x = 0.7, the Cd0.7Zn0.3S photocatalyst had the strongest surface photovoltage. It was found from photocatalytic reduction of CO2 that the highest HCOOH production rate of 342.64 μmol/(g•h) over Cd0.7Zn0.3S photocatalyst among a series of CdxZn1-xS photocatalysts were obtained under 250 W high pressure mercury lamp.

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.

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