Highly Crystalline Surface Supported Metal Organic Thin Film Materials Based ...CrimsonpublishersPRSP
Highly Crystalline Surface Supported Metal Organic Thin Film Materials Based Heterojunctions for Triplet-Triplet Annihilation Upconversion by Shargeel Ahmad* in Peer Review Journal of Solar & Photoenergy Systems
Growth, characterization, and antibacterial studies of L-Lysine single crysta...IOSRJAP
Single crystals of L-lysine added Potassium Bromide were grown by slow evaporation technique at room temperature. The crystalline nature of the grown crystal wasconfirmed using powder X-ray diffraction technique. Single crystal X-ray diffraction patterns were recorded for the structural conformation and it was found to be cubic. The UV –VIS- NIR Spectrum of the grown crystals shows less optical absorption and good transmittance in the entire visible region enabling its use in optical applications. Vickers micro hardness test was carried out to analyze the mechanical property of the grown L- lysine potassium Bromide single crystal. Thermo gravimetric analysis proved that the crystal is stable up to 600ºC. The frequency and temperature dependence of dielectric constant (εr), dielectric loss (tan δ) were also measured. The grown crystal was evaluated for its biological efficacy and found to exhibit anti bacterial activities against some select bacterial strains.
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Electron transfer between methyl viologen radicals and graphene oxidekamatlab
Methyl viologen radicals are capable of transferring electrons to graphene oxide and partially restore the sp2 network. The reduced graphene oxide serves as a scaffold to anchor Ag nanoparticles. The growth of these silver nanoparticles is dictated by the ability of RGO to store and shuttle electrons. The RGO/Ag nanocomposites discussed in the present work offer new opportunities to design next generation photocatalysts.
Visit our website, KamatLab.com, for the latest news, publications, and research from our group.
Highly Crystalline Surface Supported Metal Organic Thin Film Materials Based ...CrimsonpublishersPRSP
Highly Crystalline Surface Supported Metal Organic Thin Film Materials Based Heterojunctions for Triplet-Triplet Annihilation Upconversion by Shargeel Ahmad* in Peer Review Journal of Solar & Photoenergy Systems
Growth, characterization, and antibacterial studies of L-Lysine single crysta...IOSRJAP
Single crystals of L-lysine added Potassium Bromide were grown by slow evaporation technique at room temperature. The crystalline nature of the grown crystal wasconfirmed using powder X-ray diffraction technique. Single crystal X-ray diffraction patterns were recorded for the structural conformation and it was found to be cubic. The UV –VIS- NIR Spectrum of the grown crystals shows less optical absorption and good transmittance in the entire visible region enabling its use in optical applications. Vickers micro hardness test was carried out to analyze the mechanical property of the grown L- lysine potassium Bromide single crystal. Thermo gravimetric analysis proved that the crystal is stable up to 600ºC. The frequency and temperature dependence of dielectric constant (εr), dielectric loss (tan δ) were also measured. The grown crystal was evaluated for its biological efficacy and found to exhibit anti bacterial activities against some select bacterial strains.
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Electron transfer between methyl viologen radicals and graphene oxidekamatlab
Methyl viologen radicals are capable of transferring electrons to graphene oxide and partially restore the sp2 network. The reduced graphene oxide serves as a scaffold to anchor Ag nanoparticles. The growth of these silver nanoparticles is dictated by the ability of RGO to store and shuttle electrons. The RGO/Ag nanocomposites discussed in the present work offer new opportunities to design next generation photocatalysts.
Visit our website, KamatLab.com, for the latest news, publications, and research from our group.
Visible light assisted photocatalytic reduction of CO2 using a graphene oxide...Pawan Kumar
A new heteroleptic ruthenium complex containing 2-thiophenyl benzimidazole ligands was synthesized using a microwave technique and was immobilized to graphene oxide via covalent attachment. The synthesized catalyst was used for the photoreduction of carbon dioxide under visible light irradiation without using a sacrificial agent, which gave 2050 μmol g−1 cat methanol after 24 h of irradiation
C3N5: A Low Bandgap Semiconductor Containing an Azo-linked Carbon Nitride Fra...Pawan Kumar
Modification of carbon nitride based polymeric 2D materials for tailoring their optical, electronic and chemical properties for various applications has gained significant interest. The present report demonstrates the synthesis of a novel modified carbon nitride framework with a remarkable 3:5 C:N stoichiometry (C3N5) and an electronic bandgap of 1.76 eV, by thermal deammoniation of the melem hydrazine precursor. Characterization revealed that in the C3N5 polymer, two s-heptazine units are bridged together with azo linkage, which constitutes an entirely new and different bonding fashion from g-C3N4 where three heptazine units are linked together with tertiary nitrogen. Extended conjugation due to overlap of azo nitrogens and increased electron density on heptazine nucleus due to the aromatic π network of heptazine units lead to an upward shift of the valence band maximum resulting in bandgap reduction down to 1.76 eV. XRD, He-ion imaging, HR-TEM, EELS, PL, fluorescence lifetime imaging, Raman, FTIR, TGA, KPFM, XPS, NMR and EPR clearly show that the properties of C3N5 are distinct from pristine carbon nitride (g-C3N4). When used as an electron transport layer (ETL) in MAPbBr3 based halide perovskite solar cells, C3N5 outperformed g-C3N4, in particular generating an open circuit photovoltage as high as 1.3 V, while C3N5 blended with MAxFA1–xPb(I0.85Br0.15)3 perovskite active layer achieved a photoconversion efficiency (PCE) up to 16.7%. C3N5 was also shown to be an effective visible light sensitizer for TiO2 photoanodes in photoelectrochemical water splitting. Because of its electron-rich character, the C3N5 material displayed instantaneous adsorption of methylene blue from aqueous solution reaching complete equilibrium within 10 min, which is significantly faster than pristine g-C3N4 and other carbon based materials. C3N5 coupled with plasmonic silver nanocubes promotes plasmon-exciton coinduced surface catalytic reactions reaching completion at much low laser intensity (1.0 mW) than g-C3N4, which showed sluggish performance even at high laser power (10.0 mW). The relatively narrow bandgap and 2D structure of C3N5 make it an interesting air-stable and temperature-resistant semiconductor for optoelectronic applications while its electron-rich character and intra sheet cavity make it an attractive supramolecular adsorbent for environmental applications.
Vapor growth of binary and ternary phosphorus-based semiconductors into TiO2 ...Pawan Kumar
We report successful synthesis of low band gap inorganic polyphosphide and TiO2 heterostructures with the aid of short-way transport reactions. Binary and ternary polyphosphides (NaP7, SnIP, and (CuI)3P12) were successfully reacted and deposited into electrochemically fabricated TiO2 nanotubes. Employing vapor phase reaction deposition, the cavities of 100 μm long TiO2 nanotubes were infiltrated; approximately 50% of the nanotube arrays were estimated to be infiltrated in the case of NaP7. Intensive characterization of the hybrid materials with techniques including SEM, FIB, HR-TEM, Raman spectroscopy, XRD, and XPS proved the successful vapor phase deposition and synthesis of the substances on and inside the nanotubes. The polyphosphide@TiO2 hybrids exhibited superior water splitting performance compared to pristine materials and were found to be more active at higher wavelengths. SnIP@TiO2 emerged to be the most active among the polyphosphide@TiO2 materials. The improved photocatalytic performance might be due to Fermi level re-alignment and a lower charge transfer resistance which facilitated better charge separation from inorganic phosphides to TiO2.
Mixed-Valence Single-Atom Catalyst Derived from Functionalized GraphenePawan Kumar
Single-atom catalysts (SACs) aim at bridging the gap between homogeneous and heterogeneous catalysis. The challenge is the development of materials with ligands enabling coordination of metal atoms in different valence states, and preventing leaching or nanoparticle formation. Graphene functionalized with nitrile groups (cyanographene) is herein employed for the robust coordination of Cu(II) ions, which are partially reduced to Cu(I) due to graphene-induced charge transfer. Inspired by nature's selection of Cu(I) in enzymes for oxygen activation, this 2D mixed-valence SAC performs flawlessly in two O2-mediated reactions: the oxidative coupling of amines and the oxidation of benzylic CH bonds toward high-value pharmaceutical synthons. High conversions (up to 98%), selectivities (up to 99%), and recyclability are attained with very low metal loadings in the reaction. The synergistic effect of Cu(II) and Cu(I) is the essential part in the reaction mechanism. The developed strategy opens the door to a broad portfolio of other SACs via their coordination to various functional groups of graphene, as demonstrated by successful entrapment of FeIII/FeII single atoms to carboxy-graphene.
Vapor Deposition of Semiconducting Phosphorus Allotropes into TiO2 Nanotube A...Pawan Kumar
Recent evidence of exponential environmental degradation will demand a drastic shift in research and development toward exploiting alternative energy resources such as solar energy. Here, we report the successful low-cost and easily accessible synthesis of hybrid semiconductor@TiO2 nanotube photocatalysts. In order to realize its maximum potential in harvesting photons in the visible-light range, TiO2 nanotubes have been loaded with earth-abundant, low-band-gap fibrous red and black phosphorus (P). Scanning electron microscopy– and scanning transmission electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron microscopy, and UV–vis measurements have been performed, substantiating the deposition of fibrous red and black P on top and inside the cavities of 100-μm-long electrochemically fabricated nanotubes. The nanotubular morphology of titania and a vapor-transport technique are utilized to form heterojunctions of P and TiO2. Compared to pristine anatase 3.2 eV TiO2 nanotubes, the creation of heterojunctions in the hybrid material resulted in 1.5–2.1 eV photoelectrocatalysts. An enhanced photoelectrochemical water-splitting performance under visible light compared with the individual components resulted for the P@TiO2 hybrids. This feature is due to synergistically improved charge separation in the heterojunction and more effective visible-light absorption. The electronic band structure and charge-carrier dynamics are investigated in detail using ultraviolet photoelectron spectroscopy and Kelvin probe force microscopy to elucidate the charge-separation mechanism. A Fermi-level alignment in P@TiO2 heterojunctions leads to a more reductive flat-band potential and a deeper valence band compared to pristine P and thus facilitates a better water-splitting performance. Our results demonstrate effective conversion efficiencies for the nanostructured hybrids, which may enable future applications in optoelectronic applications such as photodetectors, photovoltaics, photoelectrochemical catalysts, and sensors.
Consistently High Voc Values in p-i-n Type Perovskite Solar Cells Using Ni3+-...Pawan Kumar
Leading edge p-i-n type halide perovskite solar cells (PSCs) severely underperform n-i-p PSCs. p-i-n type PSCs that use PEDOT:PSS hole transport layers (HTLs) struggle to generate open-circuit photovoltage values higher than 1 V. NiO HTLs have shown greater promise in achieving high Voc values albeit inconsistently. In this report, a NiO nanomesh with Ni3+ defect grown by the hydrothermal method was used to obtain PSCs with Voc values that consistently exceeded 1.10 V (champion Voc = 1.14 V). A champion device photoconversion efficiency of 17.75% was observed. Density functional theory modeling was used to understand the interfacial properties of the NiO/perovskite interface. The PCE of PSCs constructed using the Ni3+-doped NiO nanomesh HTL was ∼34% higher than that of conventional compact NiO-based perovskite solar cells. A suite of characterization techniques such as transmission electron microscopy, field emission scanning electron microscopy, intensity-modulated photocurrent spectroscopy, intensity-modulated photovoltage spectroscopy, time-resolved photoluminescence, steady-state photoluminescence, and Kelvin probe force microscopy provided evidence of better film quality, enhanced charge transfer, and suppressed charge recombination in PSCs based on hydrothermally grown NiO nanostructures.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenesunitha81
The role of V and Mn incorporated mesoporous molecular sieves was
investigated for the vapor phase oxidation of o-xylene. Mesoporous monometallic
V-MCM-41 (Si/V = 25, 50, 75 and 100), Mn-MCM-41 (Si/Mn = 50) and bimetallic
V-Mn-MCM-41 (Si/(V ? Mn) = 100) molecular sieves were synthesized by
a direct hydrothermal (DHT) process and characterized by various techniques such
as X-ray diffraction, DRUV-Vis spectroscopy, EPR, and transmission electron
microscopy (TEM). From the DRUV-Vis and EPR spectral study, it was found that
most of the V species are present as vanadyl ions (VO2?) in the as-synthesized
catalysts and as highly dispersed V5? ions in tetrahedral coordination in the calcined
catalysts. The activity of the catalysts was measured and compared with each other
for the gas phase oxidation of o-xylene in the presence of atmospheric air as an
oxidant at 573 K. Among the various catalysts, V-MCM-41 with Si/V = 50
exhibited high activity towards production of phthalic anhydride under the experimental
condition. The correlation between the phthalic anhydride selectivity and
the physico-chemical characteristics of the catalyst was found. It is concluded that
V5? species present in the MCM-41 silica matrix are the active sites responsible for
the selective formation of phthalic anhydride during the vapor phase oxidation of
o-xylene.
Scheelite CGEW/MO for luminescence - Summary of the paperJoke Hadermann
This presentation gives very shortly the highlights of our paper.
Incommensurate Modulation and Luminescence in the CaGd2(1-x)Eu2x(MoO4)(4(1-y))(WO4)(4y) (0 <=><=><=><= 1) Red Phosphors
published in Chemistry of Materials, 25, 21 (2013) 4387-4395
by Vladimir Morozov, Anne Bertha, Katrien Meert, Senne Van Rompaey, Dmitry Batuk, Gerardo T. Martinez, Sandra Van Aert, Philippe F. Smet, Maria Raskina, Dirk Poelman, Artem Abakumov, Joke Hadermann
Determining a structure with electron crystallography - Overview of the paper...Joke Hadermann
The route to a solved structure (in this case Pb13Mn9O25) on the basis of precession electron diffraction, combined with HAADF-STEM, HRTEM, EELS and EDX is shown.
Summary of the paper "Solving the Structure of Li Ion Battery Materials with Precession
Electron Diffraction: Application to Li2CoPO4F"
Oral toxic exposure of titanium dioxide nanoparticles on serum biochemical ch...Nanomedicine Journal (NMJ)
Abstract
Objective(s):
Titanium dioxide (TiO2) nanoparticles (NPs) are widely used in commercial food additives and cosmetics worldwide. Uptake of these nanoparticulate into humans by different routes and may exhibit potential side effects, lags behind the rapid development of nanotechnology. Thus, the present study designed to evaluate the toxic effect of mixed rutile and anatase TiO2 NPs on serum biochemical changes in rats.
Materials and Methods:
In this study, adult male Wistar rats were randomly allotted into the experimental and control groups (n=6), which were orally administered with 50 and 100 mg/kg body weight of TiO2 NPs. Toxic effects were assessed by the changes of serum biochemical parameters such as glucose, total protein, albumin, globulin, cholesterol, triglyceride, high density lipoprotein, alanine transaminase, aspartate transaminase, alkaline phosphatase, total bilirubin, blood urea nitrogen, uric acid and creatinine. All the serum biochemical markers were experimented in rats, after 14-days of post exposure.
Results:
Changes of the serum specific parameters indicated that liver and kidney were significantly affected in both experimental groups. The changes between the levels of total protein, glucose, aspartate transaminase, alanine transaminase and alkaline phosphatase indicate that TiO2 NPs induces liver damage. Significant increase in the blood urea nitrogen and uric acid indicates the renal damage in the TiO2 NPs treated rats.
Conclusion:
The data shows that the oral administration of TiO2 NPs (<100nm) may lead to hepatic and renal toxicity in experimental rats.
Maiyalagan, Fabrication and characterization of uniform ti o2 nanotube arrays...kutty79
TiO2 nanotubes have been synthesized by sol–gel template method using alumina membrane.
Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, UV absorption
spectrum and X-ray diffraction techniques have been used to investigate the structure, morphology
and optical properties of TiO2 nanotubes. SEM image showed that TiO2 nanotubes obtained were ordered and
uniform. The diameter and length of the nanotubes were decided by the pore size and thickness of alumina
template. Raman and XRD measurements confirmed the crystallinity and anatase phase of the TiO2 nanotubes.
The optical absorption measurement of TiO2 nanotubes exhibits a blue shift with respect to that of the
bulk TiO2 owing to the quantum size effect.
Visible light assisted photocatalytic reduction of CO2 using a graphene oxide...Pawan Kumar
A new heteroleptic ruthenium complex containing 2-thiophenyl benzimidazole ligands was synthesized using a microwave technique and was immobilized to graphene oxide via covalent attachment. The synthesized catalyst was used for the photoreduction of carbon dioxide under visible light irradiation without using a sacrificial agent, which gave 2050 μmol g−1 cat methanol after 24 h of irradiation
C3N5: A Low Bandgap Semiconductor Containing an Azo-linked Carbon Nitride Fra...Pawan Kumar
Modification of carbon nitride based polymeric 2D materials for tailoring their optical, electronic and chemical properties for various applications has gained significant interest. The present report demonstrates the synthesis of a novel modified carbon nitride framework with a remarkable 3:5 C:N stoichiometry (C3N5) and an electronic bandgap of 1.76 eV, by thermal deammoniation of the melem hydrazine precursor. Characterization revealed that in the C3N5 polymer, two s-heptazine units are bridged together with azo linkage, which constitutes an entirely new and different bonding fashion from g-C3N4 where three heptazine units are linked together with tertiary nitrogen. Extended conjugation due to overlap of azo nitrogens and increased electron density on heptazine nucleus due to the aromatic π network of heptazine units lead to an upward shift of the valence band maximum resulting in bandgap reduction down to 1.76 eV. XRD, He-ion imaging, HR-TEM, EELS, PL, fluorescence lifetime imaging, Raman, FTIR, TGA, KPFM, XPS, NMR and EPR clearly show that the properties of C3N5 are distinct from pristine carbon nitride (g-C3N4). When used as an electron transport layer (ETL) in MAPbBr3 based halide perovskite solar cells, C3N5 outperformed g-C3N4, in particular generating an open circuit photovoltage as high as 1.3 V, while C3N5 blended with MAxFA1–xPb(I0.85Br0.15)3 perovskite active layer achieved a photoconversion efficiency (PCE) up to 16.7%. C3N5 was also shown to be an effective visible light sensitizer for TiO2 photoanodes in photoelectrochemical water splitting. Because of its electron-rich character, the C3N5 material displayed instantaneous adsorption of methylene blue from aqueous solution reaching complete equilibrium within 10 min, which is significantly faster than pristine g-C3N4 and other carbon based materials. C3N5 coupled with plasmonic silver nanocubes promotes plasmon-exciton coinduced surface catalytic reactions reaching completion at much low laser intensity (1.0 mW) than g-C3N4, which showed sluggish performance even at high laser power (10.0 mW). The relatively narrow bandgap and 2D structure of C3N5 make it an interesting air-stable and temperature-resistant semiconductor for optoelectronic applications while its electron-rich character and intra sheet cavity make it an attractive supramolecular adsorbent for environmental applications.
Vapor growth of binary and ternary phosphorus-based semiconductors into TiO2 ...Pawan Kumar
We report successful synthesis of low band gap inorganic polyphosphide and TiO2 heterostructures with the aid of short-way transport reactions. Binary and ternary polyphosphides (NaP7, SnIP, and (CuI)3P12) were successfully reacted and deposited into electrochemically fabricated TiO2 nanotubes. Employing vapor phase reaction deposition, the cavities of 100 μm long TiO2 nanotubes were infiltrated; approximately 50% of the nanotube arrays were estimated to be infiltrated in the case of NaP7. Intensive characterization of the hybrid materials with techniques including SEM, FIB, HR-TEM, Raman spectroscopy, XRD, and XPS proved the successful vapor phase deposition and synthesis of the substances on and inside the nanotubes. The polyphosphide@TiO2 hybrids exhibited superior water splitting performance compared to pristine materials and were found to be more active at higher wavelengths. SnIP@TiO2 emerged to be the most active among the polyphosphide@TiO2 materials. The improved photocatalytic performance might be due to Fermi level re-alignment and a lower charge transfer resistance which facilitated better charge separation from inorganic phosphides to TiO2.
Mixed-Valence Single-Atom Catalyst Derived from Functionalized GraphenePawan Kumar
Single-atom catalysts (SACs) aim at bridging the gap between homogeneous and heterogeneous catalysis. The challenge is the development of materials with ligands enabling coordination of metal atoms in different valence states, and preventing leaching or nanoparticle formation. Graphene functionalized with nitrile groups (cyanographene) is herein employed for the robust coordination of Cu(II) ions, which are partially reduced to Cu(I) due to graphene-induced charge transfer. Inspired by nature's selection of Cu(I) in enzymes for oxygen activation, this 2D mixed-valence SAC performs flawlessly in two O2-mediated reactions: the oxidative coupling of amines and the oxidation of benzylic CH bonds toward high-value pharmaceutical synthons. High conversions (up to 98%), selectivities (up to 99%), and recyclability are attained with very low metal loadings in the reaction. The synergistic effect of Cu(II) and Cu(I) is the essential part in the reaction mechanism. The developed strategy opens the door to a broad portfolio of other SACs via their coordination to various functional groups of graphene, as demonstrated by successful entrapment of FeIII/FeII single atoms to carboxy-graphene.
Vapor Deposition of Semiconducting Phosphorus Allotropes into TiO2 Nanotube A...Pawan Kumar
Recent evidence of exponential environmental degradation will demand a drastic shift in research and development toward exploiting alternative energy resources such as solar energy. Here, we report the successful low-cost and easily accessible synthesis of hybrid semiconductor@TiO2 nanotube photocatalysts. In order to realize its maximum potential in harvesting photons in the visible-light range, TiO2 nanotubes have been loaded with earth-abundant, low-band-gap fibrous red and black phosphorus (P). Scanning electron microscopy– and scanning transmission electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron microscopy, and UV–vis measurements have been performed, substantiating the deposition of fibrous red and black P on top and inside the cavities of 100-μm-long electrochemically fabricated nanotubes. The nanotubular morphology of titania and a vapor-transport technique are utilized to form heterojunctions of P and TiO2. Compared to pristine anatase 3.2 eV TiO2 nanotubes, the creation of heterojunctions in the hybrid material resulted in 1.5–2.1 eV photoelectrocatalysts. An enhanced photoelectrochemical water-splitting performance under visible light compared with the individual components resulted for the P@TiO2 hybrids. This feature is due to synergistically improved charge separation in the heterojunction and more effective visible-light absorption. The electronic band structure and charge-carrier dynamics are investigated in detail using ultraviolet photoelectron spectroscopy and Kelvin probe force microscopy to elucidate the charge-separation mechanism. A Fermi-level alignment in P@TiO2 heterojunctions leads to a more reductive flat-band potential and a deeper valence band compared to pristine P and thus facilitates a better water-splitting performance. Our results demonstrate effective conversion efficiencies for the nanostructured hybrids, which may enable future applications in optoelectronic applications such as photodetectors, photovoltaics, photoelectrochemical catalysts, and sensors.
Consistently High Voc Values in p-i-n Type Perovskite Solar Cells Using Ni3+-...Pawan Kumar
Leading edge p-i-n type halide perovskite solar cells (PSCs) severely underperform n-i-p PSCs. p-i-n type PSCs that use PEDOT:PSS hole transport layers (HTLs) struggle to generate open-circuit photovoltage values higher than 1 V. NiO HTLs have shown greater promise in achieving high Voc values albeit inconsistently. In this report, a NiO nanomesh with Ni3+ defect grown by the hydrothermal method was used to obtain PSCs with Voc values that consistently exceeded 1.10 V (champion Voc = 1.14 V). A champion device photoconversion efficiency of 17.75% was observed. Density functional theory modeling was used to understand the interfacial properties of the NiO/perovskite interface. The PCE of PSCs constructed using the Ni3+-doped NiO nanomesh HTL was ∼34% higher than that of conventional compact NiO-based perovskite solar cells. A suite of characterization techniques such as transmission electron microscopy, field emission scanning electron microscopy, intensity-modulated photocurrent spectroscopy, intensity-modulated photovoltage spectroscopy, time-resolved photoluminescence, steady-state photoluminescence, and Kelvin probe force microscopy provided evidence of better film quality, enhanced charge transfer, and suppressed charge recombination in PSCs based on hydrothermally grown NiO nanostructures.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenesunitha81
The role of V and Mn incorporated mesoporous molecular sieves was
investigated for the vapor phase oxidation of o-xylene. Mesoporous monometallic
V-MCM-41 (Si/V = 25, 50, 75 and 100), Mn-MCM-41 (Si/Mn = 50) and bimetallic
V-Mn-MCM-41 (Si/(V ? Mn) = 100) molecular sieves were synthesized by
a direct hydrothermal (DHT) process and characterized by various techniques such
as X-ray diffraction, DRUV-Vis spectroscopy, EPR, and transmission electron
microscopy (TEM). From the DRUV-Vis and EPR spectral study, it was found that
most of the V species are present as vanadyl ions (VO2?) in the as-synthesized
catalysts and as highly dispersed V5? ions in tetrahedral coordination in the calcined
catalysts. The activity of the catalysts was measured and compared with each other
for the gas phase oxidation of o-xylene in the presence of atmospheric air as an
oxidant at 573 K. Among the various catalysts, V-MCM-41 with Si/V = 50
exhibited high activity towards production of phthalic anhydride under the experimental
condition. The correlation between the phthalic anhydride selectivity and
the physico-chemical characteristics of the catalyst was found. It is concluded that
V5? species present in the MCM-41 silica matrix are the active sites responsible for
the selective formation of phthalic anhydride during the vapor phase oxidation of
o-xylene.
Scheelite CGEW/MO for luminescence - Summary of the paperJoke Hadermann
This presentation gives very shortly the highlights of our paper.
Incommensurate Modulation and Luminescence in the CaGd2(1-x)Eu2x(MoO4)(4(1-y))(WO4)(4y) (0 <=><=><=><= 1) Red Phosphors
published in Chemistry of Materials, 25, 21 (2013) 4387-4395
by Vladimir Morozov, Anne Bertha, Katrien Meert, Senne Van Rompaey, Dmitry Batuk, Gerardo T. Martinez, Sandra Van Aert, Philippe F. Smet, Maria Raskina, Dirk Poelman, Artem Abakumov, Joke Hadermann
Determining a structure with electron crystallography - Overview of the paper...Joke Hadermann
The route to a solved structure (in this case Pb13Mn9O25) on the basis of precession electron diffraction, combined with HAADF-STEM, HRTEM, EELS and EDX is shown.
Summary of the paper "Solving the Structure of Li Ion Battery Materials with Precession
Electron Diffraction: Application to Li2CoPO4F"
Oral toxic exposure of titanium dioxide nanoparticles on serum biochemical ch...Nanomedicine Journal (NMJ)
Abstract
Objective(s):
Titanium dioxide (TiO2) nanoparticles (NPs) are widely used in commercial food additives and cosmetics worldwide. Uptake of these nanoparticulate into humans by different routes and may exhibit potential side effects, lags behind the rapid development of nanotechnology. Thus, the present study designed to evaluate the toxic effect of mixed rutile and anatase TiO2 NPs on serum biochemical changes in rats.
Materials and Methods:
In this study, adult male Wistar rats were randomly allotted into the experimental and control groups (n=6), which were orally administered with 50 and 100 mg/kg body weight of TiO2 NPs. Toxic effects were assessed by the changes of serum biochemical parameters such as glucose, total protein, albumin, globulin, cholesterol, triglyceride, high density lipoprotein, alanine transaminase, aspartate transaminase, alkaline phosphatase, total bilirubin, blood urea nitrogen, uric acid and creatinine. All the serum biochemical markers were experimented in rats, after 14-days of post exposure.
Results:
Changes of the serum specific parameters indicated that liver and kidney were significantly affected in both experimental groups. The changes between the levels of total protein, glucose, aspartate transaminase, alanine transaminase and alkaline phosphatase indicate that TiO2 NPs induces liver damage. Significant increase in the blood urea nitrogen and uric acid indicates the renal damage in the TiO2 NPs treated rats.
Conclusion:
The data shows that the oral administration of TiO2 NPs (<100nm) may lead to hepatic and renal toxicity in experimental rats.
Maiyalagan, Fabrication and characterization of uniform ti o2 nanotube arrays...kutty79
TiO2 nanotubes have been synthesized by sol–gel template method using alumina membrane.
Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, UV absorption
spectrum and X-ray diffraction techniques have been used to investigate the structure, morphology
and optical properties of TiO2 nanotubes. SEM image showed that TiO2 nanotubes obtained were ordered and
uniform. The diameter and length of the nanotubes were decided by the pore size and thickness of alumina
template. Raman and XRD measurements confirmed the crystallinity and anatase phase of the TiO2 nanotubes.
The optical absorption measurement of TiO2 nanotubes exhibits a blue shift with respect to that of the
bulk TiO2 owing to the quantum size effect.
Synthesis Of Nanostructured TiO2 Thin Films By Pulsed Laser Deposition (PLD) ...sarmad
Sarmad Sabih Al-Obaidi
Ali Ahmed Yousif
Abstract
In this work, nanostructured TiO2 thin films were grown by pulsed laser deposition (PLD) technique on glass substrates. TiO2 thin films then were annealed at 400-600 °C in air for a period of 2 hours. Effect of annealing on the structural and morphological were studied. Many growth parameters have been considered to specify the optimum conditions, namely substrate temperature (300 °C), oxygen pressure (10-2 Torr), laser fluence energy density (0.4 J/cm2), using double frequency Q-switching Nd:YAG laser beam (wavelength 532nm), repetition rate (1-6 Hz) and the pulse duration of 10 ns. The results of the X-ray test show that all nanostructures tetragonal are polycrystalline. These results show that grain size increase from 19.5 nm to 29.5 with the increase of annealing temperature. The XRD results also reveal that the deposited thin film, annealed at 400 °C of TiO2 have anatase phase. Thin films annealed at 500 °C and 600 °C have mixed anatase and rutile phases. Full Width at Half Maximum (FWHM) values of the (101) peaks of these films decrease from 0.450° to 0.301° with the increase of annealing temperature. Surface morphology of the thin films have been studied by using atomic force microscopes (AFM). AFM measurements confirmed that the films have good crystalline and homogeneous surface. The Root Mean Square (RMS) value of thin films surface roughness are increased with the increase of annealing temperature.
الخلاصة
على (PLD) النانویة بوساطة تقنیة ترسیب اللیزر النبضي (TiO في ھذا البحث، تم انماء أغشیة اوكسید التیتانیوم ( 2
الرقیقة من 400 الى 600 درجة مئویة في الھواء مدة ساعتین . ودرس تأثیر TiO قواعد زجاجیة. ومن ثم لدنت أغشیة 2
التلدین في الخصائص التركیبیة والطبوغرافیة. عوامل عدیدة لأنماء الأغشیة اخذت بنظر الاعتبار لتحدید الحالة المثلى مثل
0.4 ) باستخدام J/cm 10-2 ) ،كثافة طاقة الفیض اللیزري( 2 Torr) 300 ) ،ضغط الأوكسجین ºC) درجة حرارة القاعدة
532 بمعدل تكراریة - 1 nm التردد المضاعف للیزر النیدیمیوم- یاك الذي یعمل بتقنیة عامل النوعیة عند الطول الموجي
6 ھرتز) وامد نبضة 10 نانوثانیة. تظُھر نتائج فحوصات الأشعة السینیة أن جمیع التراكیب النانویة رباعیة متعددة )
التبلور. وان ھذه النتائج تظھر زیادة في حجم الحبیبات من 19.5 نانومتر الى 29.5 نانومترمع زیادة درجة حرارة التلدین.
نتائج الأشعة السینیة اظھرت ایضا ان الغشاء المرسب والملدن في 400 درجة مئویة لثنائي اوكسید
Preparation of Mixed Phase (Anatase/Rutile) TiO2 Nanopowder by Simple Sol Gel...IJLT EMAS
TiO2 nanopowder having both anatase and rutile
phases was prepared by a simple procedure using sol-gel method.
Titanium isopropoxide was used as a titania source and mixed
with methanol and TiO2 nanopowder was obtained after
annealing at 6000C for 1 hour in air. The specimens made from
this powder were characterized by X-ray diffraction (XRD),
Thermogravimetric analyzer (TGA) and Transmission electron
microscopy (TEM). XRD studies revealed the presence of both
anatase and rutile phases with an average crystallite size of 35 ±
5 nm. No significant weight loss up to 7000 C was observed by
TGA curve which indicates that TiO2 nanopowder is thermally
stable. TEM revealed the presence of a number of crystalline
grains in a structured matrix and selected electron diffraction
pattern showed different arrangement of diffracted rings which
confirms a phase evolution of crystalline grains of TiO2
(anatase/rutile) due to thermal annealing. Mixed phase
(anatase/rutile) TiO2 nanopowder has been reported [1], [2] to
exhibit improved photocatalytic and gas sensing properties. It is
proposed to study the gas sensing behavior of these specimens
during our research investigations on TiO2 nanopowder.
Synthesis and charecterization studies of nano ti o2 prepared via sol gel methodeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Effect of Ytterbium Substitution on the Structural and Magnetic Properties of...ijtsrd
A series of ytterbium substituted Zinc ferrites Zn YbxFe1 x 2O4 with x=0.0000, 0.0125, 0.0250, 0.0375, 0.0500 was synthesized by the solid state method. The structural characterizations of all the prepared samples were done by using X ray diffraction XRD . These studies confirmed the formation of single phase structure in all compositions. The increase in the value of lattice parameter with increase in ytterbium concentration suggests the expansion of unit cell. Crystallinity and the crystallite size are observed to increase with the concentration of Ytterbium. The substitution of ytterbium strongly influences the magnetic characteristics and this is confirmed from the magnetization measurements at room temperature. Zar Zar Myint Aung "Effect of Ytterbium Substitution on the Structural and Magnetic Properties of Nanocrystalline Zinc Ferrite" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27826.pdf Paper URL: https://www.ijtsrd.com/physics/other/27826/effect-of-ytterbium-substitution-on-the-structural-and-magnetic-properties-of-nanocrystalline-zinc-ferrite/zar-zar-myint-aung
Preparation characterization and conductivity studies of Nasicon systems Ag3-...iosrjce
Materials belonging to NASICON family of compositions Ag3-2xTaxIn2-x(PO4)3 ( x = 0.6,0.8 and 1.1)
are prepared by sol-gel method. Ethylene glycol is used as a gelating agent. All the compositions are
characterizedby powder X-ray diffraction and Fourier transform infrared spectroscopy All these
phosphates are crystallized in rhombohedral lattice with space group R3c
. These compounds exhibit
characteristic PO4 vibrational modes in their FT-IR spectra. The dc conductivity of Ag3-2xTaxIn2-x(PO4)3 ( x =
0.6,0.8 and 1.1) was also investigated.
Synthesis and Characterisation of Copper Oxide nanoparticlesIOSR Journals
Cupric oxide (CuO) nanoparticles were prepared by the chemical route by calcinations at a higher temperature from 300oC to 400 oC. For the comparison transmission electron microscopy (TEM) and x-ray diffraction (XRD) measurements were made through JCPDS. There is good agreement between data produced by spectroscopy and the microscopic measurements.
A study of lattice parameters and dielectric properties against temperature a...iosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Bicrystalline Titania Photocatalyst for Reduction of CO2 to Solar FuelsA'Lester Allen
Degussa P25, a mixture of anatase and rutile crystal structures, is the most commonly used precursor to form the photoactive layer in solar cells; however, the photocatalytic activity of rutile is inferior to brookite. This presentation discusses the enhancement in photocatalytic activity of an antase brookite mixture.
Study on Ni 0.5-X Znx Cu0.5 Fe2 O4 Sintered Ferrite System Using Xrd & High F...paperpublications3
Abstract: Nickel ,Zinc, copper Mixed spinel ferrite compound was synthesized by using High field technique method and the well ground powder is fired at 9000C for 20 hours and furnace cooled approximately at the rate of 1000C per hour. The resulting powders were characterized by X- ray diffraction (XRD). The magnetic properties of the compound analyzed by hysteresis loop measured using high field measurements.
Keywords: Ferrites, High field measurements, Hysteresis loop X - ray diffraction.
Structure and band gap energies of nano titanium dioxide doped with the fifth group elements
1. Chemical and Process Engineering Research www.iiste.org
ISSN 2224-7467 (Paper) ISSN 2225-0913 (Online)
Vol.25, 2014
Structure and Band Gap Energies of Nano Titanium Dioxide
Doped With the Fifth Group Elements
Mohsin E.Al-Dokheily
Chem. Dept. College of Science / University of Thi-Qar mohsinaldokheily@yahoo.co.uk
Abstract
Titanium dioxide powders were synthesized by adding different fifth group elements precursors to titanium (IV)
isopropoxide followed by calcination at 500-600 ⁰C. Diffractograms showed the presence of anatase phase
accept for phosphorus which has amorphous- poly crystalline phase then established a rutile phase among
heating above 500⁰C. Particle size distribution and AFM images indicate the nano dimensions of the studied
powders. Particle size distribution varied appreciably in comparison with crystallite size (L) calculated from
Scherer formula. Band gap energies calculated from Uv-Vis spectra of thin films deposited on one side of quarts
substrate. The band gap energies of –Fifth group elements of this work ranged from 2.83 eV for
to2.83 eV for Bi with a steady increase according to atomic radii accepts for antimony which deviated
from that behavior
Keywords: , Doping, fifth group, Dffractograms, AFM, Band gap
1. Introduction
The large band gap energy of anatase crystalline phase (Zaleska 2008) has imposed
significant limitations on its application particularly in the interior places. Titanium dioxide can utilize only a
limited portion of solar radiation, the UV fraction which is at most about 5 percent (Janczarek etal 2007).
Titanium dioxide is an n-type semiconductor, and that behavior arises due to oxygen vacancies and creation of
sites (Pelaeza 2012). Rutile phase posses a wider 3d band gap compared to anatase due to localization of
3d states (Di valentine and Pacchioni 2004). In spite of rutile phase has a band gap compared to of
anatase phase, yet anatase considered to have superior photocatalytic activity because of its larger surface area
(Sclafani and Hermann 1996). Extending the absorption of light to the visible range and improving
photocatalytic activity require the modification of the band gap.
Implementation of metal and non-metal ions into the lattice of as dopant will bring about a significant
lowering of gap energies. Several methods including various types of dopant (Zaleska 2008, Xz and Fa2001,
Hsuan-Chung etal 2012), those dopants include d- orbital's transition metals, but more recently non-metals
including and . Also various preparation methods were suggested including chemical vapor
deposition (Ding etal 2001) sol gel films(Brinker and Sherar 1990) multilayer deposition (Saciu etal 2009) and
pyrolysis of sprays (Raut etal 2009). Anatase titanium dioxide has a tetragonal crystal
structure, , , while rutile, has a tetragonal crystal structure
, .The presence of d-orbital and anionic dopants impair
pronounced effects on the titanium dioxide properties (Hanaor and Sorrell 2010). Those effects might lead to
reduction of the band gap by creation of new trapping sites which may also control phase transformation to
rutile. Cationic dopants may replace of the anatase lattice or may fall on the boundaries of unit cells
(Mackenzie 1975). In contrary anionic dopants might replace oxygen of the lattice (Asahi etal 2011). However
influence of doping on geometric structure of and virtually optical mechanisms have been calculated by
many researchers, (Guo and Du2012) utilized Cambridge Serial Total Energy Package (CASTEP) to study
and doped anatase . Density functional theory calculations were used to characterize the doping
effects of substituting for in anatase Tran etal 2011). The phase stability in doped was carried
out using all- electron atomic orbital's methods with local density approximation (Hanaor 2012). The effect of
doping on the surface properties of anatase and rutile were performed using photon - energy range UPS
( ) which is extremely surface sensitive (Batzill etal 2006. Substantial efforts have been subjected
toward the commercialization of doped photo catalyses of self cleaning for organic and inorganic
compounds in the environment (Fujishima etal 2006).
In this work the band gap was modified by doping with the elements of the fifth group including
and using a well established sol- gel method. The structure of prepared powders, particle size and
their distribution were identified by XRD and AFM microscopy. The band gap energies were calculated from the
UV spectra.
2. Experimental
2.1 Materials
Titanium dioxide anatase (Degussa, purity 99%) used as received without any further treatments. Doped titanium
dioxide powders were synthesized as follow: to 10 ml titanium (IV) tetraisopropoxide (Aldrich Purity 97%)
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appropriate amount of dopants precursors were added, stirred (Magnetic stirrer LMS100) at 30 forming a
viscous milky like suspension within 10 minutes ,which is then broke down to a powder after 3 -4 hours of
continuous stirring . The powder filtered, dried (Drying oven Fisher Scientific) at 120 for an hour. The dried
powder calcined at 300- 900 (Muffle furnace LEF1055, Jlabtech) for an extra hour at each preset temperature
.The following precursors were added to titanium (IV) tetraisopropoxide, 5ml of 35% ammonium hydroxide
(Aldrich) for N - , 5 ml of 1M basic solution of ( Fluka) for , 5 ml of 1M of
(BDH) for , 5 ml of 1M basic solution of (BDH) for and 5 ml of 1M of
(Fluka) for . Prepared doped powders have different color shades depending as well as on the
calcinations temperatures.
2.2 Measurements
2.2.1 XRD
Titanium dioxide and doped titanium dioxide powder XRD were recorded on PAN analytical X'pert PRO MPD
using as a source for X-ray radiation of from .
2.2.2 AFM
Two dimensional and three dimensional particles size and their size distribution were recorded by AA2000
atomic force microscope product of Angstrom Advanced Inc.
2.2.3 Band gap energies
For doped titanium dioxides films were calculated from absorbance spectra recorded on double – beam Uv-Vis
spectrophotometer (T90 +) PG instruments. The films were prepared by dipping pre-cleaned quarts substrates
vertically in a beaker containing 0.5 g of the synthesized powder suspended in 25 ml deionized water for 30
minutes. The substrate then air dried first and subsequently in an oven at 105 ⁰C for 2 hours. The films deposited
on one side of quartz substrates were placed in the sample beam, while uncoated substrate placed in the reference
path. The following equation (Mohd etal 2011) was applied
Where ν is the frequency in nm, h is the Planks constant and k is a constant. A plot of ( versus hν (eV)
gives the band gap value in eV at the intersection of a straight line drawn as a tangent with the x- axis at the
absorbance edge.
3. Results and discussions
The fifth group contains two non-metals and , as well as three metals and Bi. It's well accepted that
nitrogen among the best dopants narrowing appreciably the band gap of . According to many theoretical
studies nitrogen and phosphorus also might substitute oxygen in titanium dioxide lattice, while other metal
members of the group might replace the titanium atom in the lattice. The entire group's elements have
, outer shell configuration with atomic radii ranging from for to
for . The group's elements have a correlated opportunity to interact with (atomic radius ) and
of lattice. Therefore the fifth group will present a good model to
evaluate the effects of doping. However titanium dioxide provide three possible accommodation sites for
dopants, the two substitution site for titanium and oxygen already mentioned above, and the third to interstitial
site . The effects of doping include phase transformation from anatase to rutile, and to induce alteration in the
electronic structure leads to band gap narrowing facilitating visible light absorption. Both effects were quite
evident in forthcoming results.
Figure 1 shows XRD patterns of anatase and different calcined doped . Strong diffraction peaks
at , . ,
for anatase . Doping with the fifth group elements by the
stated above method brought some major differences into peaks positions characteristic of bare
. In the two small peaks at and appear on the shoulders of
the strong peak at of bare are being not clear indicating some structural changes.
Showed a rather different peak position at indicating
rutile phase even at early stages of calcinations which was evident at the higher calcinations temperatures. Anew
peak positions were noticed for s at , and
for . Neither nor showed rutile phase. The
ambiguity regarding the effects of the fifth group dopants on the transformation from anatase to rutile may stem
from increased density of anion vacancies as in and dopants as a result from substitution of in anatase
lattice (16) . Nitrogen as many researchers have agreed might replace oxygen in the anatase lattice efficiently
while phosphorus behaved differently. Figures2and 3 showed the effect of calcinations from for
and doped . For (Fig 2) heating up to will bring about a new weak peak at
referring to emergence of rutile phase. Heating up to 800 will turn the powder totally to a
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rutile phase which also accompanied by other characteristic rutile peaks at
. The diffraction pattern of (Fig 3) is rather different, at low
calcinations temperatures up to 500 the powder is irregular polycrystalline amorphous with low intensity,
however the prevailing phase was rutile and it's more pronounced above probably due the formation of
well defined crystal dimensions suitable for XRD measurements.
Figure 1: XRD pattern of bare and doped
Figure 2: XRD patterns of calcined at different temperatures
Figure 3: XRD patterns of calcined at different temperatures
Particle size distribution and AFM images Figures (4, 5, 6, 7, 8 and 9) indicate the nano dimensions of the
studied powders. Several measurements have been performed to assure the data. The AFM images showed
distinguished regular, smooth and generally round shapes of particles; however particle size distribution varied
appreciably in comparison with the crystal size (L) measured by Sherar formula(Monshi etal 2002 , Ahmed etal
2014) from XRD diffraction patterns namely for :
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Where is the Sherar's constant, in the present calculation a value of were adopted. Is the wavelength of
X-ray source ( ), while is the width of half maximum intensity corresponding to Bragg's angle
. Results of average particle size (nm) and the average diameters (nm) from AFM measurements as
70
well as the crystallite size L (nm) were listed in table 1.
Table 1: Measured average particle size, their size distribution by AFM and calculated crystallite size L,
band gap energies
Band
gap
(eV)
Particle Size Davg(nm) L(nm)
range(nm)
Code
60-135 84.19 26.26 3.2
50-150 95.68 26.03 2.81
80-180 130.75 59.64 2.83
30-135 90.98 59.62 2.85
70-140 91.24 49.17 2.84
55-120 78.69 59.62 2.95
Figure 4: Two and three dimensional AFM images and particle distribution of anatase
Figure 5: Two and three dimensional AFM images and particle distribution of
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Figure 6: Two and three dimensional AFM images and particle distribution of
Figure 7: Two and three dimensional AFM images and particle distribution of
Figure 8: Two and three dimensional AFM images and particle distribution of
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Figure 9: Two and three dimensional A FM images and particle distribution of
Figure 11 shows the absorbance spectra of thin films (the curves donated f, g are excluded and they don’t
belong to the fifth group elements). All of the films were considered transparent above about 460 nm although
insignificant absorption tails are still present which probably due to scattered Uv light caused by the thin films
them self’s( Salah 2013) .From figure 11 the extracted absorbance data were plotted as vs. photon
energy (eV) and presented in figures 12,13,14 and 15. Band gap energies of –Fifth group elements of
this work ranged from 2.83 eV for to2.95 eV for Bi with a steady increase according to atomic
radii accepts for antimony which deviated from that trend. Although many researchers reported rather lower
values for and powders which may attributed to the measurements of powder instead of
films and also to the different experimental conditions such as type of precursors, method of annealing and
measurement technique. However doping with the fifth group elements brought about a noticeable correlated
narrowing of the band gap energies compared with that of bare . Janezarek etal 2007 suggested a control
on the band gap energy by varying nitrogen contents through the control of calcination temperatures rather than
varying the nitrogen precursor. Recent study (Hreniak etal 2014) found similar trend for the influence of silver
on optical properties of powder .
Figure 10: Uv-Vis spectra of doped films with the fifth group elements a) b)
c) d) e)
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Figure 11: as a function of hν for the Film
Figure 12: as a function of hν for the P Film
Figure 13: as a function of hν for the As Film
Figure 14: as a function of hν for the Film
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Figure 15 as a function of hν for the Film
4. Conclusions
Doping of with the fifth group elements brought a noticeable correlated decrease in the band gap from 3.2
eV for bare anatase phase to about 2.85 eV. Synthesized powders have a nano dimensions and almost anatase
phase except for phosphorus which has amorphous – mixed phase turned to be rutile above 500 ⁰C. The method
of calculating band gap energies gave sharp and easily distinguishable values.
Acknowledgment
This work was supported by the University of Thi-Qar as a part of research and higher studies projects.
74
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