XRD Crystallite Size Research Articles

Spray-Coated Transition Metal Dichalcogenides as Hole Transport Layers in Inverted NFA-Based Organic Photovoltaics with Enhanced Stability under Solar and Artificial Light

In this study, we explored the potential of exfoliated transition metal dichalcogenides (TMDs) as innovative spray-coated hole transport layers (HTLs) in organic photovoltaics (OPVs), addressing the need for efficient and stable materials in solar cell technology. This research was motivated by the need for alternative HTLs that can offer enhanced performance under varying lighting conditions, particularly in indoor environments. Employing UV-visible absorption and Raman spectroscopy, we characterized the optical properties of MoS2, MoSe2, WS2, and WSe2, confirming their distinct excitonic transitions and direct bandgap features. The nanocrystalline nature of these TMDs, revealed through XRD patterns and crystallite size estimation using the Scherrer method, significantly contributes to their enhanced physical properties and operational efficiency as HTLs in OPVs. These TMDs were then integrated into OPV devices and evaluated under standard solar and indoor lighting conditions, to assess their effectiveness as HTLs. The results demonstrated that MoS2, in particular, displayed remarkable performance, rivalling traditional HTL materials like MoO3. It maintained high power conversion efficiency across a spectrum of light intensities, illustrating its versatility for both outdoor and indoor applications. Additionally, MoS2 showed superior stability over extended periods, suggesting its potential for long-term usage in OPVs. This study contributes significantly to the field of photovoltaic materials, presenting TMDs, especially MoS2, as promising candidates for efficient and stable OPVs in diverse lighting conditions, thereby broadening the scope of solar cell applications.

Transformation of Styrene Oxide on Bi-Functional Ni, Co and Cu Catalysts Supported on Zirconia-Alumina: Effect of Depositing Zirconia on Alumina

2-phenyl ethanol (2-PEA) and 2-phenylacetaldehyde (PAA) are important perfumery chemicals which are prepared by hydrogenation and isomerization of styrene oxide (SO) respectively. Activities of Ni, Co and Cu supported on a set of zirconia-alumina supports with varying ZrO2:Al2O3 molar ratio are compared for these reactions. Zirconia was deposited on γ-alumina by deposition-precipitation. All catalysts were characterized by XRD, NH3-TPD, H2-TPR, N2 physisorption, XPS and Raman spectroscopy. Increasing the zirconia content significantly influenced catalyst characteristics. These are correlated with reactivity: i) surface concentration of Ni, Co and Cu (XPS) decreased, which affected conversion of styrene oxide and selectivity to 2-PEA ii) 1 1 1 plane of Cu (XRD) was suppressed which enhanced selectivity of styrene by-product relative to 2-PEA iii) acidity (NH3-TPD) decreased, which adversely affected yield of PAA. Product space time yields (STY) of 2-PEA and PAA correlated well with surface concentration of active metals (XPS) and acidity (NH3-TPD) respectively. Various by-products were identified. Styrene appeared to form by deoxygenation of SO. TPR and Raman spectroscopy indicated strong interaction of Co and Ni with alumina while Cu showed strong interaction with zirconia. This reflected in their XRD crystallite size. Cu has different electronic properties than Co and Ni, which reflected in differences in their behavior. This study directly compares the performance of these transition metals in continuous flow studies and correlates catalyst characteristics with reactivity.

Structural, optical and thermoelectric properties of (Al and Zn) doped Co9S8-NPs synthesized via co-precipitation method

In the previous decade nanostructure materials have emerged as the necessary ingredient in electronic application and enhancement of device performance. Cobalt sulfide is one such transition metal sulfide which has provoked a lot of interest in the field of research. The present study was related to pure, (Al and Zn) doped cobalt sulfide NPs have been fabricated using facile co-precipitation method. The cubic structure has conformed to XRD analysis and crystallite size of pure and doped Co9S8 NPs in the range of 11 to 29 nm and with W-H method varies from 29 to 51 nm. The SEM micrograph shows that the agglomeration of the particles in the form of clusters. To conform the vibrational modes of (Al and Zn) doped Co9S8-NPs was done with Raman spectroscopy analysis. The absorbance of prepared materials was investigated with UV–VIS and it was also observed that the band gap decreased from 3.6 to 1.94 eV with doping agents. In case of IV analysis shows that the resistivity decreased and conductivity increased of Al and Zn doped Co9S8 NPs. Furthermore, the sharp increase in potential difference at lower temperature indicates that the doped material is an excellent thermoelectric material for energy storage devices.

Controlled fabrication of novel zirconia nanoparticles with tailored size, morphology, crystal phases, surface properties, and acidity via Indonesian Boehmeria virgata-mediated eco-friendly synthesis

Green synthesis of ZrO2 NPs from plant sources has gained significant attention due to its advantages, such as eco-friendly and low-cost production compared to chemical synthesis methods. The objectives of this work were to study the characteristics of green synthesized ZrO2 NPs using three types of Boehmeria virgata leaf extracts in n-hexane (ZrO2–H), methanol (ZrO2-M), and water (ZrO2–W) at various calcination temperatures (500, 700, and 900 °C). ZrO2 NPs with different structures, morphologies, surface properties, and acidity were fabricated through an eco-friendly synthesis method using three types of Indonesian B. virgata leaf extract at various calcination temperatures. The resulting ZrO2 NPs exhibited monoclinic and tetragonal phases, while a tetragonal-dominated structure was detected on ZrO2–H 700, ZrO2-M 700, and ZrO2-M 900 NPs. SEM images showed that ZrO2–H and ZrO2-M NPs possessed homogenous nanospheres shape, whereas the combination of nanoflakes and nanospheres was observed in ZrO2–W NPs. Based on the analysis of TEM micrographs, the average nanoparticle sizes of ZrO2–H, ZrO2-M, and ZrO2–W at calcination temperatures of 900 °C were determined to be 16.02 nm, 34.63 nm, and 17.63 nm respectively. The formed ZrO2 NPs prepared using BVLEs, exhibited a specific surface area ranging from 11.32 to 58.86 m2/g, a pore volume ranging from 0.058 to 0.183 cm³/g, and a pore diameter ranging from 9.85 to 58.65 nm. The acidity of ZrO2 NPs ranged from 0.0397 mmol/g up to 1.6045 mmol/g. The calcination temperature influenced the XRD crystallite size, surface texture (specific area and porosity), and acidity of ZrO2 NPs mediated by BVLEs. This green and simple synthesis method offers an alternative technique for forming highly valuable ZrO2 NPs compared to chemical synthesis methods.

Zinc oxide nanoparticles (ZnO NPs) stabilized by phytocellulose derived biopolymer and their bipartite interaction studies with agriculturally important microbes/Raphanus sativus (L.) seeds

Zinc oxide nanoparticles (ZnO NPs) are one of the most studied metal oxide NPs (MONPs) owing to their unique physiochemical properties. The last few years have witnessed a growing interest among researchers in adopting the green chemistry approach to fabricate MONPs. We herein report the synthesis of ZnO NPs stabilized by carboxymethyl cellulose (CMC) derived from noxious aquatic weed, i.e., Eichhornia crassipes biomass (EC-CMC). The UV–Vis spectra showed maximum absorbance at ∼380 nm, and the XRD crystallite size of EC-CMC capped ZnO NPs (c-ZnO NPs) (∼26 nm) was smaller as compared to virgin ZnO NPs (v-ZnO NPs) (∼29 nm). The value of apparent strain (εA x 10−3), root mean square strain (ERMS x 10−3), stress (MPa), and energy density (KJm−3) for c-ZnO NPs obtained from the SSP plot was ∼0.893, ∼0.173, ∼116 and ∼51.83 respectively. The study also examined the differential effects of c-ZnO NPs treatment on the growth of two plant growth-promoting rhizobacteria (PGPR), i.e., Pseudomonas fluorescens (Gram -ve), and Bacillus subtilis (Gram +ve). The findings revealed that P. fluorescens (PFL) was more susceptible to c-ZnO NPs than B. subtilis (BST). Furthermore, R. sativus seeds treated with c-ZnO NPs (10–50 ppm) exhibited notable improvements in plumule length, radicle length, vigor index, and biomass content over other treatments and control. The biopriming of R. sativus seeds with PFL and BST showed synergistic effects with 10-ppm c-ZnO NPs treatment and promoted overall seedling growth. The bacterial kinetics and seed germination studies manifest that the c-ZnO NPs at lower doses have growth-promoting effects. The combination of PFL + BST+10-ppm c-ZnO NPs showed substantial improvements in the germination indices of R. sativus. The present work has demonstrated the potential of utilizing positive bipartite interaction of PGPRs and bio-stabilized ZnO NPs to develop nanoformulations promoting plant growth management.

Impact of Holmium and Nickel Substitution on Y-Type Hexagonal Ferrites Synthesized via Sol-gel Method

Sol-gel auto combustion route is employed to fabricate Y-type hexagonal ferrites Ba2-xHoxSr2-yNiyFe12O22(x = 0, 0.02, 0.04, 0.06, 0.08, 0.1 & y = 0, 0.1, 0.2, 0.3, 0.4, 0.5). All prepared samples are examined through XRD, SEM, and dielectric characterization.The prepared samples were then sintered at 950 °C for 6 hours. TGA analysis was carried out to find the estimated sintering temperature for the phase development. The XRD experiment was performed to determine the effect of substitution on structural parameters. XRD crystallite size was observed in the range of 5.5 – 19.79 nm. Lattice constant (a) was found in the range 6.08 – 6.17 Å, and that of c was found in the range 44.08 – 44.73 Å. The averagegrain size value wasnoted to be around ~ 2?m as calculated through SEM.Through Raman spectroscopy, six active modes (3E1g, 2A1g, and E2g) correspond to different vibrational modes of the prepared samples. LCR technique showed that the dielectric constant and the dissipation factor were decreased with increased frequency. A decrease in dielectric losses suggests these materials are for high-frequency applications.

Effect of sintering conditions on structural and morphological properties of Y- and Co-doped BaZrO3 proton conductors

BaZrO3-based materials doped with a trivalent cation have excellent chemical stability and relatively high proton conductivity which makes them potential proton conducting oxide materials for various electrochemical device applications such as hydrogen processing, high-temperature electrolysis, and solid electrolyte in fuel cells. However, BaZrO3 showed poor sinterability, requiring high sintering temperatures (1700–2100 °C) with longtime sintering (20–100 h) to achieve the desired microstructure and grain growth. This sintering problem can be solved by slightly doping BaZrO3 with a sintering aid element. Therefore, in this study, two different zirconate proton conductors: BaZr0·9Y0·1O3-α (BZY) and BaZr0·955Y0·03Co0·015O3-α (BZYC) were sintered in an air atmosphere and an oxygen atmosphere for 20 h in the temperature range of 1500–1640 °C. The sinterability was evaluated by analyzing the XRD diffraction patterns, lattice constant, lattice strain, crystallite size, relative density, open porosity, closed porosity, surface morphology, grain size, and grain boundary distribution, using the XRD, SEM, EDX, and Archimedes density measurement methods. It is concluded that in an oxygen atmosphere, sintering aid Co not only improves the relative density but also produces highly dense fine particles with clear grain boundaries which are promising for electrochemical hydrogen device applications.

Evaluation of the physicochemical, thermal and behavioural properties of consciousness energy healing treated iron (II) sulphate

Iron (II) sulphate is used as a source of iron to treat iron deficiency anemia. In this study evaluated the impact of the Trivedi Effect®- Consciousness Energy Healing Treatment on the physicochemical, thermal, and behavioural properties of iron sulphate using modern analytical techniques. Iron sulphate sample was divided into control and treated parts. Only treated sample received the Trivedi Effect®-Consciousness Energy Healing Treatment remotely by a famous Biofield Energy Healer, Mr. Mahendra Kumar Trivedi. The powder XRD relative peak intensities and crystallite size of the treated iron sulphate were significantly altered ranging from -87.25% to 338.67% and from -58.33% to 99.84%, respectively compared to the control sample. The average crystallite size of the treated iron sulphate was significantly decreased by 5.68% compared with the control sample. The particle size values of the treated iron sulphate was decreased by 1.54% (d10), 1.12% (d50), 2.51% (d90), and 1.90% {D(4,3)} and the surface area was increased by 4.69% compared with the control sample. The melting temperature of the four peaks (1st-4th) of the treated sample was decreased by 0.28%, 12.45%, 5.44%, and 0.51%, respectively compared to the control sample. The latent heat of fusion of 1st, 2nd, and 4th peaks in the treated sample was decreased by 47.29%, 75.39%, and 0.29%, respectively, whereas 3rd peak was increased by 8.02% compared with the control sample. The total weight loss in the treated iron sulphate was increased by 0.78% compared with the control sample. The maximum thermal melting temperature of the treated sample was slightly increased by 2.03% in the 1st peak; but decreased by 1.53%, 12.64%, and 1.27% in the 2nd, 3rd, and 4th peaks, respectively compared to the control sample. Overall results suggested that the Trivedi Effect®-Consciousness Energy Healing Treatment might lead to the production of a new polymorphic form of iron sulphate, which would be more soluble and bioavailable, compared to the untreated sample. The Trivedi Effect® treated iron sulphate would be useful to design more efficacious nutraceutical/pharmaceuticals, which might offer better therapeutic response against iron deficiency anemia.

Enhanced photocatalytic Activity of Ferromagnetic Fe-doped NiO nanoparticles

The Ni1-xFexO (x = 0.00, 0.02, 0.04, 0.06 and 0.08) nanoparticles (NPs) has been synthesized via composite hydroxide mediated (CHM) synthesis approach. The single phase formation of NiO NPs was achieved without any impurity phase confirmed by XRD and average crystallite size showed minor decreasing trend with increasing Fe doping concentration. FTIR spectra showed dip in 417-432 cm−1 range which confirmed the existence of Ni-O bonding. In Raman spectra, the weak two-magnon (2 M) band at 1472 cm−1 in pure NiO NPs indicate suppressed antiferromagnetism (AFM) due to smaller average crystallite size and superparamagnetic contribution from the uncompensated surface/core spins. The absence of 2 M band in Fe doped samples is due to onset of ferromagnetism in these NPs. The M-H loops showed the room temperature ferromagnetism in Fe doped samples due to double exchange interaction of mixed valance states of Fe. The energy band gap showed minor increasing trend with increasing Fe doping concentration and is mainly attributed to Moss-Burstein effect. The photocatalytic activity showed an increasing trend with increasing Fe doping due to generation oxygen vacancies which served as energy traps and restricted the electron-hole recombination. Therefore, the bifunctional ferromagnetic Fe doped NiO NPs are more favourable for photocatalysis along with their ability of collection for re-use in the degradation process.

EVOLUTION AND CHARACTERIZATIONS OF AURIVILLIUS BISMUTH TITANATE BY MODIFIED SOLID STATE PROCESSING

Mild agate mortar activation followed by sintering of precursors, in resemblance to modified solid state process, was studied for synthesis of the aurivillius bismuth titanate. Hand on mill activation was carried out for eight hours followed by annealing treatment at 1000°C for 12 hours in presence of air atmosphere to obtain the proper phase. Scherrer’s formula was utilized to estimate crystallite size along with planes of orientation. Crystallite size was about 65nm while prominent peaks of orientations were (-117), (006), (111), (200) and others. FESEM and TEM studies were carried to obtain the morphology and estimated grain size of the synthesized aurivillius compound. Morphological features execute the material system to be nanocrystalline in nature as estimated from grain size measurement in correspondence with XRD crystallite size estimation. FTIR analysis confirms M-O coordinations of synthesized modified perovskite (aurivillius) sample. Optical property was evaluated from UV-VIS analysis with prominent absorption spectra in the visible region. Tauc plot was used to estimate the band gap to be about 2.86eV & 2eV for both direct and indirect transitions.

Novel synthesis of high surface area nano-CeZrO2: transformation of the microstructure and textural properties as the effect of calcination

Semi-crystalline and crystalline ceria-zirconia, nanoparticles had been successfully synthesized by water/oil microemulsion method at room temperature without and with calcination process. The basic understanding on the influence of microemulsion system and the relation of calcination process on the microstructure of nanoparticles was studied. Without calcination, the semi-crystalline nanoparticles with the size in the range of were produced. This size was consistent to the droplet size of microemulsion and the XRD crystallite size. In , zirconia ions incorporated into the ceria structure to form a complete solid solution of nanoparticles. The specific surface area was and it was found as a highly microporous material. While, after calcination process, the degree of crystallinity of nanoparticles increased and the fully crystalline nanoparticles were produced. The crystals and particles size grew up to 12 nm, while the surface area reduced to . However, both nanoparticles, with and without calcination, were consistent as a cubic structure. By comparing the properties of both nanoparticles samples, it can be concluded that the nanoparticles are able to be synthesized using the microemulsion method at room temperature without calcination process and it is suitable for catalysts application.

Nanostructured TiO2 thin films by chemical bath deposition method for high photoelectrochemical performance

TiO2 thin films were deposited by simple chemical bath deposition method onto conducting and non-conducting glass substrates. The resulting films were annealed at 300°, 400°, and 500 °C for 3 h. In XRD studies, crystallite size and microstrain from x-ray line broadening profile were estimated by Scherrer’s and Williamson-Hall plot method. Also, structural parameters such as unit cell volume, lattice constants, dislocation density, and stacking fault probability have been calculated. Optical absorption spectra illustrate that the band gap energy has been decreased from 3.45 to 3.19 eV with increasing annealed temperatures. Furthermore, the photoluminescence (PL) spectra exhibited two luminescence centers, one is for near-band-edge emission (NBE) and another is for deep level emission (DLE). From FT-IR spectrum of 400 °C annealed film, it was found that strong band around at 609 cm−1 is associated with the characteristic vibrational mode of anatase TiO2. The morphology and elemental composition of the 400 °C annealed film were investigated by field emission scanning electron microscopy (FESEM) and energy dispersive x-ray (EDS) analysis respectively. Present work deals with a significant photoelectrochemical cell performance of TiO2 thin films annealed at 400 °C and explored the cell parameters like conversion efficiency (η) and fill factor (FF). Finally, it was found that the deposited TiO2 films showed the outstanding PEC performance with supreme photoconversion efficiency 1.94%.

The effect of Cu addition on the morphological, structural and mechanical characteristics of nanocrystalline NiTi shape memory alloys

An attempt has been made to develop the nanostructured NiTi and NiTiCu shape memory alloys (SMAs) using mechanical milling method. The effects of milling and the addition of Cu as ternary element in NiTi SMA was analysed by evaluating its structural and morphological characteristics. Experimental results obtained from the XRD phase analysis, crystalline nature, crystallite size and lattice strain of the synthesized monocrystalline elements, confirmed the formation of B2 phase-intermetallics such as NiTiCu and NiTi. The microstructural characteristics and formation of agglomerates in case of NiTi and NiTiCu system can be altered by increasing the milling time. The results suggest that the use of mechanical synthesis for NiTi based shape memory alloys stimulates the formation of solid phase homogeneous nanocrystalline elements. Addition of Cu in NiTi resulted in the formation of nanocrystalline with a size of ∼23 nm. The diffraction patterns of nanocrystalline NiTi SMAs were characterized with diffraction rings and reduction in lattice parameter.

Crystallite size as a function of kaolinite structural order-disorder and kaolin chemical variability: Sedimentological implication

Abstract The present study aims to propose a new relationship on the thickness of fundamental kaolinite particles determined by XRD crystallite size (D001) as controlled by its structural order-disorder degree and the kaolin chemical variability (KCV). The average crystallite size (D001) values of 29 kaolinite-rich samples, belonging to two different geologic ages and depositional conditions, show similar positive correlations with the KCV multiplied by the structural order-disorder degree determined by Hinckley (HI) and Lietard (R2) indices (R2 = 0.863 and 0.853), respectively. This relationship is given by the empirical equations: D001 = 99.35 (HI × KCV) + 28.42 and D001 = 141.50 (R2 × KCV) + 24.65. The obtained values are proposed as a new chemo-structural index, named “Azhar-IACT Index”.

Effect of ambient oxygen on the photoluminescence of sol–gel-derived nanocrystalline ZrO2:Eu,Nb

The development of inorganic nanophosphors is an active research field due to many applications, including optical gas sensing materials. We found a systematic dependence of the photoluminescence (PL) of europium (Eu3+) impurity ions in zirconia (ZrO2) nanocrystals on the ambient oxygen concentration in a O2/N2 mixture at normal pressure. Europium-doped ZrO2 powders were synthesized via a sol–gel route. Heat-treatment at 1200 °C resulted in a well-developed monoclinic phase (XRD crystallite size of ~50 nm) and an intense PL of Eu3+ ions residing in the dominant phase (Eu3+ was excited directly at 395 or 464 nm). Co-doping with niobium resulted in a narrowing of the PL emission lines. Only Nb5+ was detected by XPS and is believed to charge-compensate Eu3+ activators throughout the material leading to a more regular crystal lattice.At room temperature, the exposure to oxygen suppressed the Eu3+ fluorescence, whereas, at elevated temperatures (300 °C), the effect was reversed. At 300 °C and under a focused continuous laser beam, a substantial PL response (>50%) was achieved when switching 100% of N2 for 100% of O2. PL decay kinetics clearly showed that at 300 °C fluorescence quenching centers were induced within the material by oxygen desorption.The relatively fast (<5 min) and sub-linear PL response to the changes of oxygen concentration shows that ZrO2:Eu,Nb is a promising PL-based oxygen sensing material over a wide-range of oxygen pressures.

Opto-electrical properties of ZnO:Al powders prepared in a micro drop fluidized reactor

Optical and electrical properties of ZnO:Al powders prepared in a continuous and one-step micro drop fluidized reactor were investigated. The shift of main peaks in XRD patterns and crystallite size of ZnO:Al powders increased with increasing flow rate of micro bubbles (UMB), indicating that the fluidization of micro drops during the formation of powders could help the doping of Al3+ ions into the lattice of ZnO. The band gap energy of ZnO:Al powders became narrow by forming the extrinsic donor levels to the conduction band more easily, with increasing UMB. The surface morphology of ZnO:Al powders became more wrinkled and furrowed with increasing UMB, due to the increase of micro shear force and strain acting on the surface of ZnO:Al during the formation in the fluidization field of the reactor. The room temperature photoluminescence indicated that the doping effects of as-prepared ZnO:Al powders were getting better with increasing UMB. The electrical resistivity of ZnO:Al decreased considerably due to the active generation of extra free electrons at the surface of the powder, with increasing UMB.

Synthesis, spectral characterization, DNA interaction, anticancer and molecular docking studies on some transition metal complexes with bidentate ligand

The ligand, N2,N3-bis(3-nitrophenyl)quinoxaline-2.3-diamine was prepared by the condensation of quinoxaline-2.3(1,4H)-dione with 3-nitroaniline. It was treated with Co(II), Ni(II), Cu(II) and Zn(II) acetates to form the metal complexes. These were characterized by elemental analysis, molar conductance, magnetic moment, UV–Vis., IR, 1H NMR, ESR and mass spectral data. Octahedral geometry has been assigned to Co(II), Ni(II) and Zn(II) complexes, whereas Cu(II) complex has distorted octahedral geometry. From the powder XRD data, crystallite size and unit cell parameters were calculated. The surface morphology of the synthesized compounds were determined using SEM analysis. The antimicrobial activity of the compounds against some bacterial species viz. Escherichiacoli, Klebsiella pneumoniae, Pseudomonas aeuruginosa and Staphylococcus aureus; also the fungal species, Aspergillus niger, and Candida albicans were done by disc diffusion method. DNA binding, cleavage and super oxide anion scavenging activities were also evaluated. The DNA binding activity of the compounds were identified using electronic absorption titrations and DNA cleavage was determined using gel electrophoresis. The anticancer activities of the compounds against HeLa cell line were determined using MTT assay. The highly potent compound among the five against HeLa cell line is subjected to molecular docking study against human papilloma virus receptor molecule and ATP binding site of telomerase.

Feasibility of formation of nanocrystalline Fe-Cr-Y alloys: Mechanical properties and thermal stability

Aim of the present study is to investigate the feasibility of formation of Fe-Cr-Y disordered solid solutions by mechanical alloying and effect of Y on the thermal stability and mechanical properties of such nanocrystalline alloys. Thermodynamic analysis by Miedema's and Toop's models confirms that the energy barrier required to form the disordered solid solutions has been overcome by the stored energy due to strain dislocations and grain boundary defects. Although limited grain growth was observed during annealing of metastable Fe-15Cr-1Y alloy, the grains size found to stabilize at ~53nm after annealing at 1000°C; and the corresponding hardness value measured to be also quite high (8GPa). The grain size analysis by TEM and AFM is well-corroborated with the XRD crystallite size. The high thermal stability and large strengthening effect have been discussed in the light of grain boundary pinning by solute segregation, solute drag effect and Zener pinning due to intermetallic phase(s).

Augmentation of thermoelectric performance of VO2 thin films irradiated by 200MeV Ag9+-ions

Abstract Swift Heavy Ion (SHI) irradiation with 200 MeV Ag9+-ion beam at ion fluences of 1E11, 5E11, 1E12, and 5E12 for tuning of electrical transport properties of VO2 thin films fabricated by so–gel technique on alumina substrates has been demonstrated in the present paper. The point defects created by SHI irradiation modulate metal to insulator phase transition temperature, carrier concentration, carrier mobility, electrical conductivity, and Seebeck coefficient of VO2 thin films. The structural properties of the films were characterized by XRD and Raman spectroscopy and crystallite size was found to decrease upon irradiation. The atomic force microscopy revealed that the surface roughness of specimens first decreased and then increased with increasing fluence. Both resistance as well as Seebeck coefficient measurements demonstrated that all the samples exhibit metal–insulator phase transition and the transition temperatures decreases with increasing fluence. Hall effect measurements exhibited that carrier concentration increased continuously with increasing fluence which resulted in an increase of electrical conductivity by several orders of magnitude in the insulating phase. Seebeck coefficient in insulating phase remained almost constant in spite of an increase in the electrical conductivity by several orders of magnitude making SHI irradiation an alternative stratagem for augmentation of thermoelectric performance of the materials. The carrier mobility at room temperature decreased up to the beam fluence of 5E11 and then started increasing whereas Seebeck coefficient in metallic state first increased with increasing ion beam fluence up to 5E11 and thereafter decreased. Variation of these electrical transport parameters has been explained in detail.

Effect of growth temperature and time on the ZnO film properties and the performance of dye-sensitized solar cell (DSSC)

This paper reports the synthesis of ZnO nanorods via seed-mediated growth hydrothermal technique and their application in dye-sensitized solar cells (DSSCs). The growth process was carried out at various temperatures, namely 60, 70, 80, and 90 °C for 8 h at 0.1 M zinc acetate dehydrate (ZAD) to investigate the effect of growth temperature on the property of ZnO sample and on the performance of the DSSC-containing ZnO sample. The growth process was also carried out at various growth times, namely 2, 4, 6, and 8 h at 90 °C at 0.1 M ZAD to investigate the effect of growth time on the property of ZnO sample and on the performance of the DSSC. It was found that the morphology of ZnO nanorods in terms of grain size and length increases with the growth temperature. The peak intensity of XRD patterns, crystallite size, optical absorption, and photocurrent also increase with the growth temperature. The optical absorption and power conversion efficiency (η) increase as the growth time increases. The DSSC utilizing the ZnO nanorods synthesized at 90 °C for 8 h demonstrates the JSC, VOC, FF and η of 1.860 mA cm−2, 0.52 V, 0.287, and 0.277 %, respectively.