Doping Percentage Research Articles

Up and down conversion photoluminescence and structural properties from hafnium doped with different lanthanides and lithium

The structural and photoluminescent results of the lanthanum, erbium, ytterbium and lithium doped hafnium oxide phosphors; are presented. These powders were synthesized by the solvent evaporation technique, different percentages of doping of the lanthanides were carried out, obtaining monoclinic and cubic phases, also a cubic phase is present when doping lanthanides with 28% mol. Up-conversion (UC) and down-conversion (DC) luminescence spectra when excited with a 980 nm laser, three emission regions are presented; two in the visible (up-conversion) and one in the infrared (downshift), are observed. The green emission located at 528 nm, 543 nm and 559 nm; associated whit transitions of erbium ion (2H11/2 + 4S3/2) → 4I15/2 and in the red emission located at 653 nm and 678 nm; associated whit transitions of erbium ion (4F9/2 + 4I9/2) → 4I15/2. In 1532 nm, the infrared down conversion associated electronic transition 4I13/2 → 4I15/2 of erbium ion. The luminescence emission intensity increase in green is 336 times and in red is 105 times when doping with lithium in comparison with samples without lithium co-doped.In the XRD diffractograms shown the monoclinic, cubic and mix of the phases in the phosphors; these are confirmed with the TEM diffraction patterns. The EDS result indicates the presence of HfO2, Er3+ and Yb3+, in the phosphorus; hafnium decreases due to the presence of ions lanthanides. XPS showed changes in energy values due to doping of lanthanides. The CIE diagram indicates that HfO2 doped phosphors have a variety of shades from red to yellow.

Characterization of Ag-doped ZnO thin films by spray pyrolysis and its using in enhanced photoelectrochemical performances

In this work, Ag:ZnO thin films have been prepared by spraying a mixture of zinc acetate dehydrate and silver nitrate precursors on (ITO)-coated glass substrates at optimized conditions of substrate temperature and a solution concentration. In the current study, we show the effect of Ag doping on the morphological and photoelectrochemical properties of ZnO thin films. The SEM observations exhibit indeed a low change in the size of the surface crystallite after doping. For instance, we have investigated the silver doping effect on the electrochemical behavior taking place at the ZnO/electrolyte interface. The interface has been modeled as an equivalent circuit consisting of a parallel charge transfer resistance RCt and a constant phase element (CPE) in series with a resistance of electrolyte RS. An optimization of the doping percentage has shown that the ZnO photoanode doped with 2% Ag gives the best photoelectrochemical performances.

Enhanced properties of the chemically prepared Gd-doped SrSnO3 thin films: Experimental and DFT study

Abstract In the present paper, we investigate in detail the Gd doping effect on the properties of the chemically prepared SrSnO3 thin films. Unlike previous preparation attempts that utilized a very sophisticated vacuum methods and high annealing temperature, a very simple path was followed by employing the simple ultrasonic spray method with an annealing process at only 800 °C, resulting a high quality films. The crystallographic identification using XRD analysis confirmed the formation of SrSnO3 phase crystallizing in the orthorhombic structure with Pbnm space group. The percentage of the gadolinium doping affected the obtained structure majorly after passing the 5%. Structural properties were further investigated with Raman and FT-IR analysis confirming the results obtained by the XRD. Morphology and chemical composition of Gd-doped SrSnO3 thin films were evaluated using a field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray spectrometer (EDX). The surface scanning shows an amelioration in the morphology of the films as dopant ratio increased, while EDX and mapping analysis confirmed the purity of the resulted films with the presence of the dopant element. The Gd-doping effect on the optical properties was noticed through the decrement of the transparency of the films and the dropping of the band gap from 3.88 to 2.85 eV for the 7% of dopant content. The first principles calculations revealed a major modifications on the electronic and optical properties of SrSnO3 generated by the 4f state of Gd. A remarkable variation of the band gap was measured decreasing from 4.08 eV to 2.17 eV, which emphasizes our experimental findings.

Waste Paper Managment

This manuscript investigates the waste paper management (WPM) of an educational Institute and aware the people about the importance of waste paper management and recycling of waste papers by multidimensional approach. The research assessed two multi long term plans, considering all recycling settings feasible for educational scenario. To complete that purpose, support for the collection of waste papers, final disposal its environmental and financial impact assessment concerning to transportation is also required. Results suggest that the quality of handmade papers is improved by doping some external materials in cellulose of waste papers. In this manuscript, flour of wheat is mixed in waste paper cellulose. The analysis of handmade paper is done by photometric test. It is found that at some percentages of doping of flour in waste paper pulp, the reflection properties of the paper is increased and surface of paper become smooth and hard. At some other percentages of doping, the papers are shown absorption properties. The traditional papers are manufactured in paper mills and the industries are one of the major source of responsible for air, water and land pollutions. By recycling of waste papers & rags, the handmade papers are produced which may become the alternate of all types of papers. Recycling can help to keep the city clean. Papers are manufactured by wooden pulp and for this; the trees are cut from the forest. Recycling of waste papers is one solution to protect environment, deforestation, soil erosion, which can also lead to disaster like kedarnath disaster in 2013 and major threat to the atmosphere. Recycling of paper can also proved to be a new source of employment and can become a hot area for startups, as we have recently seen many various startups in the field of recycling, such as e-waste recycling, plactic recycling, etc.

Impact of Ag doping on structural, optical, morphological, optical and photoluminescent properties of ZnO nanoparticles

An investigation of room-temperature sol–gel synthesis Ag doped ZnO nano-particles are reported here. The effect of silver concentration (2, 4, 6, 8 and 10 at. wt.%) on the morphology, structural and optical properties of the Ag doped ZnO nanoparticles are studied. XRD analysis displays the hexagonal wurtzite structure. The crystallite size was found to decrease in the range 36.95–28.11 nm with the increase in Ag dopant percentage. With enhancement in the Ag contents, the crystallite size decreases and specific surface area increases which suggest their use in biological science and photocatalysis. Surface morphology shows that grains are irregular, cuboid, linear and spherical shaped nanoparticles with slightly varying sizes. The Ag doped ZnO nanoparticles show interesting properties, which are modified by the change of the grain size with increase in Ag dopant percentage. The band gap of the nanoparticles decreases with increase in Ag doping where 10 at. wt.% Ag dopant nanoparticles have a notably lower band gap than that of undoped ZnO (3.37 eV). Photoluminescence spectra has shown the violet shift emission bands. The optical properties predict the use of Ag doped ZnO nanoparticles in solar cells, optoelectronics, spintronics and wastewater treatment.

Dielectric and magnetic properties of dilute magnetic semiconductors Ag-doped ZnO thin films

Ag-doped ZnO thin films are prepared by the cost-effective sol–gel dip-coating method at room temperature. The Ag dopant percentage varies between (2–10) wt%. The magnetic and dielectric properties have been studied. The dielectric and magnetic properties of ZnO are significantly tailored by the increase in the Ag doping percentage. High dielectric constant and tangent loss have been observed at low frequencies which decreases with the increase in frequency. The AC conductivity is lower in the low-frequency region but has larger values in the high-frequency region. The ferromagnetic behavior of films has been recorded at room temperature. Magnetic polarons play a pivotal role in the development of room temperature ferromagnetism in Ag-doped ZnO thin films. So, ferromagnetism in thin films is governed by bound magnetic polarons. As the doping concentration increased, the saturation magnetization decreased and coercivity increased due to the combined effect of the decrease in crystallite size, generation of large defects, and formation of bound magnetic polarons. These Ag-doped ZnO thin films are suitable for spintronics.

Investigations on the efficiency variation of zinc and gallium Co-doped TiO2 based dye sensitized solar cells

In this research the electric performances of Dye Sensitized Solar Cells (DSSCs) using titanium dioxide (TiO2) photoanodesco-doped with 1% Zn & (0%, 0.5%, 1% and 1.5%) Ga has been investigated. The films of undoped and co-doped TiO2 have been deposited by sol gel dip coating technique. The structure and optical properties of pure and 1% Zn & (0%, 0.5%, 1% and 1.5%) Ga co-doped TiO2 films are investigated. XRD spectra reveal that studied films hasanatase tetragonal structure of TiO2with a small shifting angle when the doping percentages of Zn and Gaare increased. The crystallites have an average size in the range of 11–18 nm. Calculated lattice parameters are well matched with the reported value. a-axis remains same with doping while c-axis varies with doping. UV–Vis spectroscopy results show that band gap energy (Eg) is decreased with doping. Maximum decrease in Eg is found at the doping percentage of 1% Zn and 1% Ga and value is 3.20 eV. The efficiency of realized DSSC is increased considerably compared to that using pure TiO2 photoanode. The current versus voltage (I–V) characteristics reveal that the DSSC prepared using 1% Zn & 1% Ga co-doped TiO2 layer has significantly improved parameters. This cell has a high power conversion efficiency of 4.36%, short current density of 7.24 mA/cm2 and open circuit voltage of 0.86 V.

Transparent boron-doped zinc oxide films for antibacterial and magnetic applications

B-doped ZnO thin films have been synthesized by a sol–gel dip-coating deposition technique. Deposition conditions were optimized to achieve highly ordered thin films. XRD patterns confirm that B ions are inserted into the ZnO; lattice and the crystallite size decrease from 25.83 to 20.94 nm as the amount of B increases to optimal value (9 at.wt%). Synthesized B-doped ZnO thin films have ordered hexagonal wurtzite structures and granular morphology with high specific surface area. Optical transmittance spectra display transparency in the visible region. The band gap of the films decreases from 3.89 to 3.04 eV with the increase in B concentration. Band gap lowering is due to increase of defect level with the increase in B dopant percentage. The origin of the ferromagnetism is explained in terms of oxygen vacancies and Zn interstitials. Dielectric constant increases while DC conductivity and AC conductivity decrease with the increase in B doping. Antibacterial activity increases with the increase in B doping percentage but lower than undoped ZnO due to large crystallite size of B-doped ZnO nanostructures.

Influence of Sn doping ratio on the structural and optical properties of CdO films prepared by laser induced plasma

In this work, we study the effect of doping Sn on the structural and optical properties of pure cadmium oxide films at different concentrations of Tin (Sn) (X=0.1,0.3 and 0.5) .The films prepared by using the laser-induced plasma at wavelength of laser 1064 nm and duration 9 ns under pressure reached to 2.5×10-2 mbar. The results of X-ray diffraction tests showed that the all prepared films are polycrystalline. As for the topography of the films surface, it was measured using AFM , where the results showed that the grain size increases with an increase in the percentage of doping in addition to an increase in the average roughness. The optical properties of all films have also been studied through the absorbance spectrum of the range of the wavelength (350-1100) nm, where the optical energy gap was direct transitions it was found that the value of the optical energy gap increased with increasing the doping.

Permittivity-Customizable Ceramic-Doped Silicone Substrates Shaped With 3-D-Printed Molds to Design Flexible and Conformal Antennas

3-D-Printing in antenna design is a recent research branch which is attracting academic and industrial interest. Nevertheless, despite the advantages in terms of antenna customizability, common filaments exhibit limitations in some contexts where platform tolerability, flexibility, and compactness are simultaneously required. Indeed, other than a rather low permittivity of commercial 3-D-printable materials, when flexibility is required, also significant loss tangent values must be accounted. To address this problem, a method to realize conformable flexible low-loss substrates with increased and customizable permittivity is proposed in this communication. It is based on the synthesis of ceramic-doped silicone structures shaped through 3-D-printed molds by using alumina and barium titanate as ceramic filler. Different substrates were firstly realized and characterized in terms of permittivity and loss tangent at different doping percentages. Then, a first validation on 2.4 GHz conformal patch antennas exploiting both third dimension and increased permittivity is presented. Finally, a wearable and compact bracelet-shaped UHF RFID planar inverted-F antenna (PIFA)-inspired flexible antenna is designed, tested when applied on the human body, and compared with a previously realized version 3-D-printed in polylactic acid. In spite of comparable performance, the novel device exhibits considerable size reduction and improved wearability, thus confirming the effectiveness of the proposed approach.

Study of the Structural and Optical Properties of Ni-doped Co3O4 Thin Films Using Chemical Spray Pyrolysis Technique

Undoped and Ni-doped Cobalt oxide thin films (Co3O4:Ni) with doping percentage (3, 6, and 9%) have been prepared by chemical spray pyrolysis technique on glass substrates at (400 °C). The structural, surface morphology and optical properties were studied. XRD results showed that all the films were polycrystalline and had a cubic structure with preferred orientation (111) plane for all doping. The AFM images appear to be smooth and homogenous films. The optical properties showed that the transmittance decreased by increasing the percentage of Ni, and the direct optical band gap decreased from (2.53 eV) to (2.32 eV) for undoped Co3O4 with increasing the doping percentage to (9%).

Assessment of antibacterial and optical features of sol-gel dip coated La doped TiO2 thin films

The effect of Lanthanum ions (La3+) has been investigated on TiO2 thin films with varying La doping percentage from 6 to 10 at.wt. La ions have incorporated into the TiO2 lattice, while no lattice changes in TiO2 has taken place. The band gap of La-doped TiO2 thin films varies with increase in La dopant percentage. SEM images show a nanocrystalline morphology and agglomeration of the grains at high dopant percentage. Higher value of dielectric constant (31.5) and low tangent loss (0.021) are observed. Variation in DC conductivity with change in frequency is recorded by applying Jonscher's power law. AC conductivity is linked with barrier-hopping mechanism. La doped TiO2 thin films show room temperature ferromagnetism. The La doped TiO2 has shown little antibacterial activity.

Fabrication of heterostructure solar cell using the optimized Sn incorporated PbS films via atomized nebulizer spray pyrolysis

Thin films of PbS doped with tin (2 ≤ Sn ≤ 8 wt.%) were deposited on glass substrates by cost- effective nebulizer spray method. X-ray diffraction studies confirm the polycrystalline nature with a face centered cubic structure along with the orientation of (200) plane. SEM/AFM studies reveal that the nano-sized spherical and granular shaped grains roofed the whole film surface and the grain shapes were changed with the change in Sn doping percentage. Bandgap was found to decrease from 1.98 eV to 1.66 eV with an increase in the doping concentration from 2 to 6 wt%. Hall Effect measurement confirmed p-type conducting nature for all the doped PbS films. The resistivity and carrier concentration values are found to be about 0.32 × 103 Ωcm and 6.78 × 1013 cm−3, respectively, for the optimized PbS:Sn film (6 wt%). The response of the heterostructured (FTO/n-CdS/p-PbS:Sn/Ag) solar cell with the optimal Sn doping (6 wt% Sn) was studied under dark and illuminated conditions.

Optoelectronic properties of Zn-doped Cu3Se2 nanosheets for photovoltaic application

Thin films of Zn-doped copper selenide (Cu3Se2) nanostructures with different Zn concentrations were deposited on fluorine-doped tin oxide (FTO) glass substrates by electrodeposition method. The structural, optical, electrical, and photovoltaic properties of the deposited films were investigated by different analyses. X-ray diffraction (XRD) pattern showed the crystalline and tetragonal structure of the samples. The results of XRD pattern also showed that the peaks shifted to higher angles by increasing the Zn dopant, indicating the influence of dopant on the crystalline structure of Cu3Se2. Electron microscopy analysis showed that the films had a sheet-like shape whose thickness changed by altering the dopant percentage; the highest number of sheets belonged to the samples with higher concentrations of dopant. The photoluminescence (PL) analysis of the Cu3Se2 nanostructures revealed that the peaks in the green and infrared regions shifted to shorter wavelengths and the intensity of emission peaks increased for the Zn-doped sample with the highest concentration, compared with the un-doped sample. Based on the absorption spectrum analysis, the optical energy band gap increased with raising the percentage of Zn dopant. Finally, the electrical and photovoltaic parameters of the solar cells prepared via Cu3Se2 nanosheets were examined. The doped sample which had the highest percentage of doping, showed the highest efficiency (η) of ~1.30%.

Improved device performance of solution-processed red-colored Cu–In–Zn–S-based quantum dot light-emitting diodes enabled by doping TCTA into the emitting layer

The working mechanisms in the cadmium-free Cu–In–Zn–S(CIZS)-based quantum dot light-emitting didoes (QD-LEDs) were reported in previous reports, which were mai nly determined by the direct charge injection or the energy transfer. In this paper, we presented an improved device performance in solution-processed red-colored CIZS-based QD-LEDs by doping a small molecule 4,4′,4″-tris-(carbazol-9-yl)- triphenylamine (TCTA) into the emitting layer, and the best peak current efficiency of 3.22 cd A−1 and maximum luminance (Lmax) of 2679 cd m−2 could be achieved by optimizing the doping percentage of TCTA in the CIZS/ZnS nanocrystals (NCs). Such red-colored QD-LEDs exhibited a 210% increase in the current efficiency and no obvious change in the electroluminescence (EL) spectra as compared with the QD-LEDs without TCTA. The improvement of the device performance could be attributed to the synergistic effects of more balanced hole injection and the effective exciton energy transfer from TCTA to the NCs. The balanced hole injection could be verified by the fact that an increased current efficiency in the QD-LEDs by doping TCTA into an organic hole-transport layer.

Synthesis, characterization, and performance evaluation of pristine and cerium‐doped WO3 nanoparticles for photodegradation of methylene blue via solar irradiation

AbstractIn this study, an effective photodegrading properties of WO3 nanoparticles has been enhanced by doping with cerium. To achieve our goal pristine and Ce‐doped WO3 nanoparticles were prepared by a simple and cost effective co‐precipitation route. Characterization of all the specimens were conducted which showed that there were no noticeable structural changes. WO3 retained its monoclinic structure even after doping with (3%, 5%, 8%, 10%) cerium which was also confirmed with X‐ray diffraction (XRD) and Raman spectroscopy. In addition, XRD and Fourier transform infra‐red spectroscopy also confirm that no new phases were formed in doped specimens. XRD also depicts that minimum crystallite size is achieved at 3% cerium doping. Scanning electron microscope images show decrease in particle size initially at 3% cerium doping, that is, ~80 ± 2.5 nm. In contrast, further increase in doping percentage increases crystallite and particle sizes. Additionally, defect generation increased at lower doping percentage ~3%. In contrast, further increase in dopant (5%, 8%, 10%) caused defect annihilation process to dominate over defect generation. C/Co ratio and rate constant (KMB) values suggest that maximum degradation of methylene blue will occur at 3% cerium doping due to increase in crystalline defects. Ultraviolet visible Spectroscopy further validates C/Co ratio and degradation rate constant values by showing drastic decline in peak intensity at 3% cerium doping. Therefore, 3% cerium‐doped WO3 is more effective photocatalyst to degrade methylene blue in comparison to most of the previously used photocatalysts. The prepared cerium‐doped WO3 nanoparticles as a sun light driven photocatalyst, may be utilized for industrial wastewater purification.

(Invited) Heteroatom Functionalization of N- and B-Doped Graphene

One of the most important issues in the field of graphene for electronic and optoelectronic applications is how to modulate effectively the density of charge carriers, their mobility and their energy levels. One general strategy for achieving this goal is doping graphene with heteroatoms; in this approach, the properties of graphene are controlled by the nature of the dopant elements and by the percentage of doping. For example, by substituting carbon atoms with nitrogen or boron, it is possible to turn graphene into a semiconductor of n- or p-type, respectively. Both elements are by far the most common dopant elements and graphene doped with these heteroatoms have been widely used in electrocatalysis, as photocatalysts and as electronic materials.Here, we will present our work in the N- and B- functionalization of N- and B-graphene [1-4] and the influence of the nature of substituent on the electronic properties of the material.[1] M. Barrejón et al. Chem. Commun. 2015, 51, 16916[2] M. Barrejón et al. Chem. Sci. 2018, 9, 8221[3] L.M. Arellano et al. Chem. Commun. 2019, 55, 9999[4] H. Gobeze et al. Nanoscale Adv. 2019, 1, 4009

New Materials to Battle the Transistor Interconnect Bottleneck

With ever decreasing transistor size, materials that combine both diffusion barrier and liner material properties are needed to successfully electroplate Cu and thus beat the current interconnect bottleneck. In order to facilitate coating of high aspect ratio vias, the material should be as thin as possible. One possibility to achieve this is presented in this study, where we investigate through density functional theory, the behavior Cu on Ru-doped and Ru passivated ε-TaN (1 1 0). Initially, the adsorption, diffusion and association of one and two Cu atoms on the different surfaces was studied in order to probe the early stages of film growth. This showed that, while surface diffusion of atoms was more favourable on the Ru-passivated surface, the Ru dopant acts as a nucleation site for Cu, with atoms preferentially diffusing towards it.In order to understand the mechanism of film growth on this surface in more detail and to fine-tune the barrier and liner properties of the material, the effect of different percentages of surface doping were studied. Further, the behavior of Cu13 and Cu29 clusters on different doped surfaces and on the passivated surfaces was investigated. In particular, the study focused on the pathways toward agglomeration as well as the associated activation energies. We find that on a Ru doped surface the atoms agglomerate spontaneously to form a two-layer film, whereas they remain in a monolayer on Ru-passivated TaN (1 1 0).

Theoretical investigation of molybdenum/tungsten-vanadium solid solution alloy membranes: Thermodynamic stability and hydrogen permeation

To improve the resistance to hydrogen embrittlement and hydrogen permeation performance of vanadium (V) membranes, first-principles calculations were employed to study the stability, dissolution, and diffusion properties of H in transition metal (M = Mo, W)-doped V membranes, as well as their mechanical and thermodynamic properties, as alternative candidates for H2 separation. Our results revealed that the doping percentage of Mo/W alloying can significantly improve the mechanical and thermodynamic properties of pure V. The most stable location for adsorbed H atoms is the tetrahedral interstitial site (TIS) in the body-centered cubic structure of the V1-xMx (x = 0.0625, 0.125, 0.1875, and 0.25) alloys. Additionally, the hydrogen migration path should preferentially follow TIS → nearest-neighbor TIS. An M content of 0.25 yields the best anti-hydrogen embrittlement and the highest hydrogen-diffusion properties. The addition of individual Mo or W as doping elements into the V-based system greatly enhanced the hydrogen diffusion coefficient, and the addition of both Mo and W significantly improved the anti-hydrogen embrittlement of V-based alloys. Our results also showed that hydrogen concentration markedly influenced the solubility and diffusivity of hydrogen in V-based alloy membranes. These results provide a basis for the design of V-based alloy hydrogen permeation membranes.

Physical and electrical properties’ evaluation of SnS:Cu thin films

ABSTRACT This paper reports successful fabrication of copper-doped tin sulphide (SnS:Cu) thin films using nebulized spray pyrolysis. Different Cu doping concentrations (2, 4, 6, and 8 wt-%) were employed to coat SnS:Cu thin films. The fabricated SnS:Cu thin films were structurally confirmed by X-ray diffraction and Raman scattering analyses. Energy-dispersive X-ray result has proved Cu atom doping within the SnS matrix. Atomic force microscopy has identified topographical modifications on SnS:Cu thin films due to Cu doping concentration. UV-visible-NIR spectroscopy was used to derive the optical band gap in the range of 1.38–1.59 eV depending on Cu doping percentage. Hall Effect measurements were employed to analyze the electrical conductivity of SnS:Cu thin films. A p-n junction FTO/n–CdS/p–SnS:Cu/Al prototype device was constructed with photo response behaviour under dark and illumination circumstances.