Increase In Crystallite Size Research Articles

High-performance ammonia gas sensor based on spray pyrolysis developed In2O3:La films

La doped indium oxide (In2O3:La) thin films were deposited on glass substrate by nebulizer spray pyrolysis by different La doping concentrations. The crystalline structure, morphology, optical and gas sensing properties of thin films were investigated. XRD diffractograms present cubic crystal structure of In2O3 films, with decreased crystallite size with the incorporation of La dopants. SEM analysis of thin film samples exhibits approximately cube-shaped morphology without any cracks of microstructures. The optical band gap magnitude shows shift in energy values in the range of 3.12–3.29 eV with increasing La concentrations. For all films, the photoluminescence spectra showed violet-blue emission peaks at around 420–480 nm. All of the developed films were tested for ammonia (NH3) gas detection at ambient temperature. In2O3:La 5% sensor had the highest gas response value of 1720%, a quicker response and recovery times of 48/12 s, respectively, suggesting the sample could be better suited for the application of NH3 gas sensor.

Structural and optical properties of Mg doped TiO2 nanoparticles synthesized by sol-gel method

Pure and doped titanium oxide (TiO2) nanoparticles with various atomic wt% (0 %, 3 %, 5 % and 7 %) of Mg were prepared by sol-gel method followed by the calcination at 100 °C for 12 h to investigate structural, optical and photoluminescence properties of TiO2 nanoparticles. Subsequently prepared samples annealed at 400 °C for 2 h for crystallization. Eventually, as prepared samples have been characterized using X ray diffractometer, scanning electron microscopy (SEM), Fourier transform Infrared Spectroscopy (FTIR), UV–Visible spectroscopy and Photoluminescence spectroscopy. XRD analysis shows that, prepared samples are crystalline in nature with exhibit of mixed phase (Rutile and Anatase) of TiO2. The crystallite size obtained around 12.0 nm of pure TiO2 nanoparticles. As increase in the doping concentration crystallite size was reduced to 6.76 nm. SEM images demonstrate the uniform growth of nanoparticles. Doping offering the tuning the energy band gap of TiO2. Photoluminescence spectra observed near UV to visible region. The intensity of Photoluminescence emission enhanced with increase of Mg doping at various concentration. Band gap and photoluminescence emission properties of doped TiO2, can be useful for optoelectronic applications and as Photo catalyst. The possible mechanism of coordination for different properties for TiO2 nanoparticles with various doping concentration have been well discussed.

Evaluation of graphene microstructural and optical properties affected by high-temperature annealing and rapid cooling in a nitrogen-rich environment

Annealing at high temperatures holds the possibility of concentrating defects in the graphene. Moreover, a significant increase in annealing temperature destroys the surface properties. In this work, the reduced graphene oxide (RGO) was prepared by an electrochemical technique with a high voltage ([Formula: see text][Formula: see text]V, [Formula: see text][Formula: see text]A). Then, the potential effects of impact on thermal treatment in a temperature range of 800–1000∘C in nitrogen-rich environment on the microstructure and surface morphology, thermal stability, phase and crystallinity, structural disorder, absorption properties, and optical properties of RGO for optoelectronic applications were investigated. In addition, a link was established between the estimated crystallite sizes determined by X-ray diffraction (XRD) and Raman data. The microstructural data indicate that the annealing temperature has a significant effect on the microstructure and carbon–oxygen (C/O) ratio. The C/O ratio increases as a function of annealing temperature. Atomic force microscope (AFM) analysis revealed that the root mean square (RMS) roughness of annealed RGO increases with increasing annealing temperature indicating an increase in crystallite size during annealing. Since most organic compounds were removed from the surface of the annealed RGO, oxygen functionalities appear to have minimal effect on the thermal stability of RGO. The size of graphene crystallites increases with annealing temperature, as shown by XRD observations. The crystalline structure was restored by annealing. The Raman results show that in the “low” defect density zone, the [Formula: see text] values increase because a larger defect density causes a stronger elastic scattering. UV–Vis spectroscopy shows that the absorption of RGO is not affected by annealing temperatures between 800∘C and 900∘C. The optical bandgap of annealed RGOs decreases from 4.08 to 3.72[Formula: see text]eV upon annealing in the temperature range of 800–1000∘C.

Solution‐based fabrication of copper oxide thin film influence of cobalt doping on structural, morphological, electrical, and optical properties

In this study, Cobalt (Co) doped Copper Oxide (CuO) films at different concentrations were deposited on glass substrates, using the Chemical Bath Deposition (CBD) method. The films were characterized by Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), Ultra Violet-Visible Spectroscopy (UV-Vis.) and two-point contact method. The FESEM images showed that nanoplates formed increased in size and voids on the films surface decreased with increasing Co concentration. The XRD patterns revealed an increase in crystallite size with increasing (from 14.40 to 18.60 nm) Co concentration and no secondary phase was formed. The Energy-dispersive X-ray spectroscopy (EDS) spectra showed the presence of Co in the film composition with increasing concentration. The results of UV-Vis. spectroscopy showed that band gap values could be changed with Co doping and thus the CuO band gap could be adjusted with the Co doping. The temperature-dependent current-voltage measurement results obtained with the two-point contact method showed that activation energy levels increased (from 0.134 to 0.232 eV) with increasing Co concentration. It was also observed that the conductivity increased with increasing temperature.

Enhanced Ionic Conductivity of Fluoride-Doped LiTi<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> as Solid Electrolyte of Lithium-Ion Battery

In this study, LiTi2(PO4)3 (LTP) was synthesized by the addition of lithium fluoride (LiF) of 0 %, 5 %, and 10 wt.%. A wet solid-state reaction method is applied by mixing Li2CO3, TiO2, and NH4H2PO4 into a ball mill, then calcined at 900o C for 12 hr. XRD pattern of Fluoride-doped LTP is indexed and found in two phases. First is the Nasicon phase (LiTi2(PO4)3) with rhombohedral structure, and second, the Olivine phase (LiTiPO5) with orthorhombic structure at the addition of 5 % and 10 wt. % of LiF. The higher LiF decreases the cell volume while the crystallite size, particle size, and material density increase. The morphology of the Fluoride-doped LTP is increasingly homogeneous and more rectangle-shape. LTP 2, adding 10 wt. % of LiF, has high ionic conductivity at 4.77 10-4 S cm-1 as a promising candidate material for solid-electrolyte of lithium-ion battery.

Vacuum-evaporated PbS:0.03 Zn thin films with varying thicknesses for environmental applications

In this research, we explore how the thickness of PbS-doped Zn thin films made through thermal vacuum evaporation affects their physical properties for environmental applications. Our x-ray diffraction (XRD) examination shows that the films consist of pure crystalline cubic PbS phase. Additionally, the energy-dispersive X-ray spectroscope (EDXS) provides confirmation that the synthesized products are of high purity. PbS films doped with Zn have spherical nanocrystals ranging from 130 nm to 250 nm in size, as observed through field emission (FE)-scanning electron microscopy (FE-SEM) analysis. The thickness of the film layer was found to correlate significantly with an increase in crystallite size and grain size, as validated by both XRD and FE-SEM analyses. The optical energy gap (Eg) of the thin films under examination exhibited variations in relation to their respective thickness. Bandgap energy was found to decrease from 1.66 eV to 1.2 eV as film thickness was increased from 50 nm to 250 nm. The Arrhenius law shows that films with varying thicknesses have thermally activated electrical conductivity and exhibit two conduction mechanisms. After analyzing the photocatalytic decomposition of methylene blue, it was observed that a thicker (PbS)0.97(Zn)0.03 film with a larger grain size demonstrated superior photocatalytic efficiency (92 % after an exposure duration of 180 min). This is due to a smaller band gap and the presence of defect sites, which enhance catalytic reactions. The study presents a framework for researching the controllable structure, thickness, and composition of chalcogenide semiconductor thin films for environmental applications.

Evolution of carbon nanostructures during coal graphitization: Insights from X-ray diffraction and high-resolution transmission electron microscopy

The evolution of carbon nanostructures during coal graphitization was investigated. The X-ray diffraction (XRD) results showed that amorphous and microcrystalline carbon coexist in anthracite and meta-anthracite, and the latter has a higher proportion of microcrystalline carbon; additionally, semi-graphite and coal-based graphite are mostly composed of crystalline carbon. Coal graphitization starts in anthracite, accompanied by an increase in crystallite size and a decrease in interplanar spacing nonlinearly, especially in semi-graphite, and a large ordered structure is formed in coal-based graphite. The high-resolution transmission electron microscopy (HRTEM) results intuitively reveal the graphitization process by false-colored microphotography, and both the XRD and HRTEM results indicate similar evolution paths. Four types of carbon nanostructures, namely, amorphous, turbostratic, concentric and graphitic-like structures, are identified according to their morphology. Aromatic fringes are arranged randomly in the amorphous structure and are composed of amorphous carbon; local ordering occurs in the turbostratic structure and is commonly observed in anthracite and meta-anthracite. In addition, a concentric structure with hollow pores and parallel annular aromatic fringes was observed, indicating multiple preferred orientations, and the graphitic-like structure was composed of parallel aromatic fringes. Micropores provide the necessary adjustment space for the ordered conversion of carbon nanostructures, and the flattening and merging of micropores may contribute to the enhancement of graphitization.

Effect of molar concentration on optoelectronic properties of NiO nanoparticles for p-n junction diode application

In this work, fine nickel oxide nanoparticles (NiO NPs) were successfully made utilizing a straightforward co-precipitation approach at low temperature. The effects of precursor concentration on the structural, optical, and electrical characteristics of NiO nanoparticles were investigated. All indexed diffraction peaks in XRD demonstrate the production of NiO with cubic structure. An increase in NiO crystallite size above 16.8 nm was observed when the precursor concentration exceeds 2 M, suggesting the presence of nanostructure in the final product. In FT-Raman spectra, the band centered at ∼ 500 cm–1 is due to Ni-O stretching (LO) mode, and two-magnon (2 M) scattering mode causes the band at 1514 cm–1. The synthesized product is composed of almost rod-shaped particles with a size range of 10–20 nm, according to FESEM pictures. The UV absorption studies showed a high absorption at the fundamental absorption edges originating at 332 nm, which gradually shifted to a lower energy region up to 400 nm with increasing precursor concentration, which means a reduction in bandgap values. The effect of precursor concentration associated with the electrical characteristics of the produced NiO nanoparticles has been investigated for the temperature range 30 to 130 °C. The I-V characterization was used to compute the different photo-diode parameters including n, ФB, Io, PS, R, QE, and D* . The remarkable high photosensitivity of 1100% and specific detectivity of 4.324 × 10−10 Jones for the diode evaluated at 120 mW/cm2 was observed in a 2 M fabricated diode. These findings imply that all the fabricated diodes are exceptionally light-sensitive and are well-suited for upcoming UV photodetector applications.

Morphological and structural properties of bismuth-nickel ferrite synthesized by a combined sol-gel method

In this paper, Bi x Ni1-x Fe2O4, (x = 0, 0.3, and 0.5), nanoparticles were synthesized by a sol–gel method, and the synthesized samples were calcination at 350 and 650o C for 3 h. The influence of Bi doping on morphological and structural properties was studied. The field emission scanning electron microscopy (FESEM) analysis showed all of the specimens contain a compact order of homogenous nanoparticles with a spherical form and polyhedral particles with an average size ranging from 36.305 nm to 27.554 nm at 350 and 650o C respectively. By studying the energy dispersive spectrometer analysis patterns, the existence of constituent elements, Ni, Bi, Fe, and O, was verified with a proportion very close to the stoichiometry of the chemical formula. The formation of a ferrite phase was confirmed by X-ray diffraction. An increase in the average crystallite and grain size has been observed with an increase in Bi doping. The Fourier Transform Infrared(FT-IR) studies were made in the frequency range 400-4000 cm-1 and observed two strong absorption peaks. The frequency band is found at 555 cm-1 whereas the lower frequency band is at 1338.5 cm-1. It is noticed that the two prominent absorption bands were slightly shifted towards the higher frequency side with the increase of Bi3+ ion concentration.

Tuning Microstructural Attributes of Spinel Cobalt Ferrite (CoFe2O4) Nanoparticles through Annealing Temperature

Background: The study systematically investigates the influence of annealing temperatures, ranging from 500°C to 900°C with 100°C increments, on the microstructural characteristics of cobalt ferrite (CoFe2O4) nanoparticles. Methods: The nanoparticles, with sizes between 7-18 nm, were synthesized using the co-precipitation method. X-ray diffraction (XRD) analysis reveals that higher annealing temperatures correspond to noticeable increases in crystallite size, lattice parameter, unit cell volume, and interatomic distances within both octahedral and tetrahedral sites. Concurrently, a substantial decrease is observed in the average theoretical X-ray density, dislocation density, and microstructural strain. This investigation elucidates the underlying physical and chemical processes driving these transformations. To explore and quantify the intricate relationships between annealing temperature and various microstructural attributes of CoFe2O4 nanoparticles, Pearson’s correlation coefficient (r) serves as a robust statistical tool. The study establishes significant associations and elucidates the strength and direction of these correlations. Results: Regression analysis yields highly robust correlations (Adjusted R-Squared > 0.99) between microstructural features and annealing temperature. These correlations provide valuable predictive insights into microstructural characteristics, offering substantial support for optimizing CoFe2O4 nanoparticle applications across a temperature range spanning from 500°C to 900°C. Conclusion: This research contributes to the scientific understanding of materials engineering and offers practical guidance for applications requiring precise control over nanoparticle properties.

Visible-range and self-powered photodetectors with SnSe nanostructures: The influence of copper concentrations and ultrasound waves irradiation on optoelectronic performance

Recent studies on tin selenide (SnSe) nanostructures have primarily focused on their thermoelectric performance, with limited attention given to their optoelectronic potential. In this study, we investigate the physical and optoelectronic properties of SnSe nanostructures with varying concentration of Cu doping and exposure to ultrasound radiation. The results reveal that increasing the concentration of the dopant element and utilizing ultrasound irradiation not only led to reduced stress and strain but also led to an increase in crystallite size. For instance, crystallite size increased dramatically up to 8.96 nm and 17.54 nm for doping and radiation of ultrasound waves in comparison to the undoped SnSe, respectively. Field emission scanning electron microscopy (FESEM) results indicate the presence of nanorods accompanied by agglomerated particles dispersed throughout all samples. The extent of doping and the parameters related to ultrasound irradiation significantly influence the shapes of these nanostructures. Photoluminescence (PL) analysis demonstrates that these influential parameters cause shifts in emission bands and changes in their intensity. Absorption spectra measurements in the range of 200–1100 nm reveal an increase in absorption due to the influence of effective parameters. Furthermore, alterations in the optical energy band gap (Eg) indicate that it enhanced within the range of 1 to 1.68 eV. The I-V characteristics results show that these influential parameters contribute to the enhancement of responsivity (0.369 to 0.467 mA/W) and sensitivity (572% to 1826%). The specific detectivity ranges from 2.90 to 10.60 × 10+9 Jones. These effective parameters also have a favorable impact on mobility, ideality factor, and carrier concentration.

Investigation on structural, optical and anti-bacterial properties of organic additives iron oxide prepared by chemical route method

Technology and Nanoscience have a remarkable impact on environmental challenges. Scientists are moving away from harmful chemical approach and toward eco-friendly, accessible, efficient, and affordable green chemical methods for synthesizing nanoparticles. This article provides a feasible way to make iron oxide using an Avicennia marina dry fruit, seeds, leaves and green fruit extract. Structural, optical and morphological properties of the manufactured iron oxide nanoparticles have been evaluated using X-ray diffraction spectroscopy (XRD,) Ultra violet visible spectroscopy (UV–Visible), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope spectroscopy (SEM) and antibacterial activity. The formation of FeO NPs and their crystallinity has been confirmed by XRD, average particle size of FeO NP of dry fruit, seeds, leaves and green fruit are 7.1335 nm, 9.295 nm, 9.680 nm and 10.128 nm respectively. FT-IR spectrum shows the surface functionalization and vibrational phases of the bonds in FeO NPs. Band gap energies decreasing as crystallite size increases, according to UV visible results band gap energies of dry fruit, seeds, leaves and green fruit are 3.16 eV, 2.57 eV, 2.99 eV and 2.52 eV respectively. The antibacterial properties of the produced nanoparticles against Xanthomonas campestris pv vesicatoria, Erwinia spp, Escherichia coli bacteria has been investigated. Iron oxide nano particles has been utilized for antibacterial activity because of their less toxicity, high stability and biocompatibilities. The result shows the produced FeO NPs were minimize on bacterial colony.

Effect of Manganese-Doping on the chemical and optical properties of cobalt ferrite nanoparticles

We report on the effect of manganese (Mn) doping on the structural, chemical and optical properties of cobalt ferrite (CFO) nanoparticles (NPs). The Mn(II)-substituted CFO NPs with variable chemical composition (Co1-xMnxFe2O4; x = 0.0–0.5; CMFO) were synthesized by an eco-friendly hydrothermal route. The CMFO NPs produced were with a crystallite size varying in the range of 8–14 nm, where the chemical valence state, chemical bonding, electronic structure and optical properties are strongly influenced by the Mn-substitution. The X-ray diffraction (XRD) studies revealed the Mn-substitution induced changes in CFO crystal structure. The Mn-substitution in CFO causes the lattice parameter enhancement (a), crystallite size increase, and micro-strain (ε) as evident in the XRD studies. The chemical composition driven direct, functional relationship reflected in a-D-ε correlation, which suggests the Mn-substitution allows the ability to control the size and strain in CFMO NPs. Chemical bonding analyses using Fourier transform infrared spectroscopy (FTIR) corroborates with structural assessment made with XRD studies. The MTd–O (MTd = metal ions in tetrahedral locations) absorption bands shifting to higher wavenumbers in FTIR studies indicate that, Mn-substitution induce changes in the metal cation distribution between the tetrahedral and octahedral locations of the ferrite lattice. The X-ray photoelectron spectroscopic (XPS) analyses indicate the presence of iron as Fe+3, cobalt as Co+2, and manganese in Mn+2 chemical state. With increasing Mn-content, the XPS revealed that the binding energy (BE) separation of Fe, as well as Mn, does not change compared to Co, indicating the chemical stability and valence state of Fe+3 and Mn+2 cations maintained well in the CMFO samples. While the overall chemistry of CFO is maintained, and is not influenced by the increasing Mn-concentration, the remarkable effect of Mn-substitution is seen on the optical properties of CFO NPs. The optical studies indicate that the band gap of CFO NPs exhibits a direct, functional dependence on Mn-concentration; the band gap varies in a wide range of 2.38–3.12 eV. The analyses indicate the exponential dependence of CFO optical band gap with Mn-content which provide a roadmap to engineer the materials with tunable band gap for desired technological applications.

Changes in the macro and nano-structure of paper during moisture cycling

Hygroexpansion, CP/MAS 13C-NMR, WAXS and SAXS measurements were carried out on sheets made from four different commercial pulps of varying lignin content. Non-directional laboratory sheets were made at different press levels from the pulps following different degrees of beating. The sheets were dried both freely and with restraints. Measurements were made on sheets before and after moisture cycling to determine hygroexpansion coefficients, changes in cellulose average lateral fibril dimensions and average cellulose crystallite sizes, with the aim of understanding macroscale and nanoscale changes as the result of moisture cycling. Within the sheets consistent and statistically significant structural changes were observed on both macro and nanoscale. On the macroscale, moisture cycling consistently induced irreversible shrinkage in sheets dried with restraints, but less so in the case of sheets dried freely. The hygroexpansion coefficients were typically higher for freely dried sheets compared with sheets dried with constraints. On the nanoscale, moisture cycling consistently caused an increase in the average crystallite sizes (WAXS) and the average lateral fibril dimensions (CP/MAS 13C-NMR), though the latter occurred with poor statistical significance. These changes were interpreted as an increase in the degree of order in the cellulose fibril interior/cellulose crystallite. There were no profound differences in the nanoscale changes observed for sheets dried with restraints and for sheets dried freely. Changes in the fibre wall nanostructure were of similar magnitudes when comparing results from freely dried low grammage sheets (less abundant inter-fibre joints) with freely dried sheets of higher grammage (more abundant inter-fibre joints). No obvious correlations were found between the macroscale and nanoscale measurements. The proposed explanation for this was that the nanoscale structural changes occurred similarly throughout the entirety of the fibre wall, independent of the proximity to an inter-fibre joint, and that the nanoscale structural changes were mainly the result of water penetrating into the interior of cellulose fibril aggregates. By using the same fibril model for evaluation of CP/MAS 13C-NMR and WAXS data, good-to-reasonable agreement were found for estimates of the degree of cellulose crystallinity.

Crystallinity tuning of LCNO/graphene nanocomposite cathode for high-performance lithium-ion batteries

In this work, a graphene-enhanced LiCo0.525Ni0.475O2 (LCNOG) cathode was synthesized by self-propagating high-temperature synthesis and the effects of annealing at 650–850 °C were investigated. Sharper X-ray diffraction peaks showed enhanced crystallization with an increase in average crystallite size from 28 nm to 56 nm after annealing at 850 °C. LCNOG annealed at 850 °C delivered a high capacity of over 2030 J compared to 1280 J, with a near ideal coulombic efficiency of 99.5 % and long cycle stability. The acceleration of kinetics is evidenced by more favorable redox peak positions in voltammetry and a 5-fold lower interfacial resistance in electrochemical impedance spectroscopy. The improved performance is due to the larger grain size, higher crystallinity, increased conductivity and graphene-induced diffusion facilitation. The relationship between crystallinity and cathodic properties provides critical insight into cathode design. The exceptional performance achieved by tailoring crystallinity through annealing makes LCNOG a potential material for high-voltage cathodes for lithium-ion technology.

Exploring the synergistic influence of Cu and Co co-doping on the optical properties of ZnO nanoparticles

In this study, we synthesized Cu and Co co-doped ZnO nanoparticles, denoted as Zn1-2xCuxCoxO (x = 0.01, 0.02, 0.03), using the sol-gel auto-combustion method. Successful integration of Cu and Co elements into the ZnO host lattice was confirmed through a comprehensive array of spectroscopic techniques. Structural analysis revealed the persistence of a hexagonal wurtzite crystal structure with some distinct microstructural variations across all samples. Alteration in lattice parameters and dislocation density strongly suggests the successful incorporation of Cu2+ and Co2+ ions within the ZnO lattice. A prominent increase in crystallite size from 27.19 nm to 33.46 nm was observed with the increase in doping concentration. Field emission scanning electron microscopy showed a combination of uniformly distributed spherical and hexagon-like structures. Furthermore, UV–Visible absorption spectra demonstrated a proportional enhancement in energy band gap from 2.14 eV for Zn0.98Cu0.01Co0.01O to 2.40 eV for Zn0.94Cu0.03Co0.03O. The Burstein−Moss effect was invoked to elucidate the observed blue shift in absorption spectra and energy band gaps, further solidifying our findings. The systematic and substantial correlation between dopant concentration and energy band gap signifies that the co-doping of Cu and Co is a viable strategy for engineering the band gap of ZnO. This collective investigation unveils the substantial potential of Cu and Co co-doping in ZnO nanoparticles for advanced optoelectronic applications, paving the way for tailored optical and photonic functionalities.

Enhancement in the Magnetic Properties of Yttrium Orthoferrite Materials by the Addition of BaO–Bi2O3–B2O3 Glass Sintering Aid

The addition of powdered BaO–Bi2O3–B2O3 (BBBO) glass (0.25–1.5 wt%) to yttrium orthoferrite materials (YFeO3) powder facilitates an increased crystallite size, resulting in improved magnetic properties. The required YFeO3 (YFO) materials are synthesized through the sol–gel route using tartaric acid as a chelating agent, while BBBO glass is obtained via the conventional melt‐quenching technique. The crushed glass is added to YFO powders in different wt% and compacted at room temperature, subsequently; the compacted samples are sintered at 1000 °C for 3 h. The X‐ray powder diffraction studies infer that a maximum 1.0 wt% of BBBO glass is incorporated into YFO without showing any impurity phase. The optical bandgap of each sample is calculated using the UV data with the help of the Kubelka–Munk and Tauc relation, decreasing from 2.10 to 2.04 eV with an increase of BBBO content from 0 to 1.0 wt% in YFO. The highest magnetization value (4.02 emu g−1) is observed with 1.0 wt% BBBO added in YFO surpassing pure YFO and other BBBO‐added YFO samples. In conclusion, the improved magnetization value of the 1.0 wt% BBBO added in the YFO sample can be potentially utilized in different applications.

Effect of synthesis temperature on crystal structure, optical and magnetic properties of SmCuO3-δ ceramic phosphor

Effect of synthesis temperature on crystal structure, optical and magnetic properties of SmCuO3-δ ceramic phosphor is investigated in this work. The SmCuO3-δ ceramic has been synthesized using a sol-gel method. Rietveld analysis reveals that SmCuO3-δ ceramic crystallizes into coexisting tetragonal (I4/mmm) and monoclinic (C2/c) crystal structures. The phase fraction of the tetragonal and monoclinic phases strongly depends on the synthesis temperature. The crystallite size and particle size increase with increasing calcination temperature. The X-ray photoelectron spectroscopic spectra reveal the presence of (Cu2+, Cu3+) and (Sm2+, Sm3+) ions alongwith the oxygen vacancy centres in the phosphor. The SmCuO3-δ ceramic shows multiple magnetic phase transitions. The FTIR spectra show the presence of vibrational bands due to Cu-O and Sm-O groups. The optical band gap of the SmCuO3-δ phosphor decreases with an increase in calcination temperature and crystallite size. The photoluminescence excitation spectra show the peaks at 363, 402, 505 and 542 nm at the fixed emission wavelength of 609 nm, whereas the photoluminescence emission spectra contain peaks at 465, 515 and 609 nm at the fixed excitation wavelength of 402 nm. The photoluminescence emission intensity of the sample increases with the rising calcination temperature upto 900 °C and finally, it quenches at 1000 °C. Therefore, the SmCuO3-δ ceramic phosphor may be useful for solid state lighting, LEDs and magnetic devices.

Improved Efficiency and Stability of Perovskite Solar Cells by Binary Perovskite–Organic Composite Thin Film

Regulating perovskite film crystallization and avoiding bulk defects during the deposition process are essential for achieving perovskite solar cells (PSCs) with excellent power conversion efficiency (PCE) and stability. Herein, the synergistic effects between n‐type, narrow‐bandgap conjugated organic molecules (2,2′‐((2Z,2′Z)‐((5,5′‐(4,4,9,9‐tetrakis(4‐hexylphenyl)‐4,9‐dihydros‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,7‐diyl)bis(4‐((2‐ethylhexyl)oxy)thiophene‐5,2‐diyl))bis(methanylylidene))bis(3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile [IEICO]) and perovskites on film surface morphology and stability, and the regulation mechanism on bulk defects in MAPb(I0.97Br0.03)3:IEICO films are explored. The results of theoretical and experimental studies indicate that a large number of electrons on the CO and C≡N surface functional groups of IEICO can function as Lewis bases and exhibit strong interactions with uncoordinated Pb2+ ions, substantially reducing bulk defects. Moreover, the resulting MAPb(I0.97Br0.03)3:IEICO film exhibits an optical response in the near‐infrared region and an increased crystallite size. Consequently, the MAPb(I0.97Br0.03)3:IEICO PSCs with a p–i–n device structure demonstrate a PCE exceeding 20%. In addition, the MAPb(I0.97Br0.03)3:IEICO PSCs possess superior stability and negligible photocurrent hysteresis. These results suggest that the incorporation of near‐infrared organic molecules into perovskites provides a simple method to achieve high‐performance PSCs and realize the utilization of near‐infrared wavelengths.

EFFECT OF HEAT TREATMENT ON THE STRUCTURE AND FUNCTIONAL CHARACTERISTICS OF A PtCo/C CATALYST

The PtCo/C electrocatalyst obtained by the method of simultaneous reduction of metal precursors using sodium borohydride was treated at a temperature of 350 ˚C in an argon atmosphere for 1 hour. The results of X-ray phase analysis and transmission electron microscopy indicate an increase in the average size of crystallites and the formation of nanoparticle agglomerates after heat treatment. The shift in the reflection of Pt (111) after treatment indicates the possible segregation of metal components during the heating of the sample. An increase in the catalyst activity after heat treatment is shown, both mass activity and specific activity. The stability of the sample after heat treatment, according to the results of the stress test in the potential range of 0.6–1.4 V, showed a higher value than the material in the “as prepared” state.