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a Scanning electron microscope image of LaFeO3 nanoparticles. b Scanning electron microscope image of LaFeO3-rGO nanocomposite. c, d EDX analysis of LaFeO3 nanoparticles and LaFeO3-rGO nanocomposite
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Perovskite-graphene nanocomposites of rare-earth LaFeO3-rGO and LaFeO3 nanoparticles are synthesized and characterized. The preparation was done by citrate sol-gel method. The structural characterization has been performed using XRD and FT-IR. Scanning electron microscope (SEM) and atomic force microscope (AFM) were used to analyze the morphology o...
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... The environmental and energy challenges the world faces over these decades are found to be huge with remarkably few available strategies of solution. These challenges have led to the growing market demands on modern photonic metal and metal oxide perovskites, silica-based, carbon-based materials, and polymer-based nanomaterials, with the capability for miniaturization, higher efficiency, optical and electrical tunable controllable properties, pollution removal capacity, and stable performance [1]. The scientific and engineering communities have taken a remarkable and commendable approach to mitigating these challenges through the design, development, and application of novel nanomaterials. ...
The synthesis and crystallographic stability of Cs⁺-doped Na2ZrO3 perovskite were explored to enhance optical properties and CO2 sorption at low temperatures (500 °C). Perovskite nanoparticles (∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim$$\end{document} 20 nm) crystallize in monoclinic C 2/c symmetry and undergo a partial transformation to a new rhombohedral (Hex) R3¯m\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R\overline{3 }m$$\end{document} symmetry during synthesis. The newly obtained atomic coordinates are discussed with respect to their Wyckoff site multiplicity. The incorporation of Cs⁺ significantly improves perovskite stability (from t = 0.807 to t = 0.916). Optical band gap analysis reveals a reduction in photon energy from 3.91 to 3.54 eV, making it a promising photonic material due to its low phonon energy (≥430cm-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge 430 {{\text{cm}}}^{-1}$$\end{document}). Additionally, Cs concentration induces a porous structure that enhances CO2 capture capacity, as observed in CO2 sorption analysis.
... The cubic unit cell parameter a and the crystal size of nanoparticles are calculated using equation (2) and equation (3), using XRD diffraction patterns results, respectively. Equation (3) is Williamson-Hall equation [56][57][58], which is used to calculate crystalline size and average lattice strain. where W is the full-width half maximum of the XRD peaks, λ is the wavelength of the used x-ray radiation (λ Cu = 1.54056 ...
This study investigates the effects of Sr²⁺ substitution on the structural, morphological, and magnetic properties of magnetic cobalt ferrite (CoFe2O4). Through sol–gel auto-combustion synthesis, Sr²⁺ was substituted into Co-spinel ferrites (Co1-xSrxFe2O4, where x = 0.0, 0.25, 0.5, 0.75, 1.0). SEM analysis revealed spherical grains with an average size of 54.4 nm. XRD analysis indicated systematic changes in crystallographic parameters and the formation of secondary phases with Sr-substitution. While the crystal size for CoFe2O4 was calculated as 262 nm, this value was determined as 18 nm for Co0.25Sr0.75Fe2O4. FT-IR results suggested increased force constants of octahedral and tetrahedral bonds with higher Sr content, with main vibration bands at 423.6 and 606 cm⁻¹. M-H curves exhibited S-shaped behavior, indicating drastic magnetic property changes with Sr²⁺ substitution. Coercivity field (Hc), saturation magnetization (M S ), and remanent magnetization (M r ) values ranged from 1447.8–545.4 Oe, 58.8-14 emu g⁻¹, and 36.8-7.6 emu g⁻¹, respectively. Blood compatibility experiments highlighted Co0.75Sr0.25Fe2O4 nanoparticles with significantly low hemolysis rates compared to other concentrations.
... However, this metal is expensive and difficult to adhere to a silicone layer (Singh and Prajapati 2020). Graphene has been introduced as a new optical material to overcome the limitations of other materials (Fu et al. 2016;Abdel-Aal and Abdel-Rahman 2020). This material has a hexagonal lattice structure which is mechanically firm (Kravets et al. 2014). ...
In this paper, a new and simple structure of a photonic crystal fiber (PCF) surface plasmon resonance biosensor is designed for detecting aqueous solutions. The graphene and magnesium fluoride (MgF2) materials are used externally around the PCF to increase the sensitivity of the sensor. The performance of the sensor is analyzed using the finite element method. The numerical results show that the proposed PCF provides an average wavelength sensitivity (Sw) and amplitude sensitivity (SA) as high as 4000 nm/RIU⁻¹ and 16,905.15 RIU⁻¹, respectively, for analytes with refractive indices (RIs) ranging from 1.33 to 1.342. When the MgF2 layer is eliminated from the structure, the values of Sw and SA are decreased to 2500 nm/RIU⁻¹ and 12,155.2 RIU⁻¹, respectively. Therefore, it is concluded that adding an MgF2 layer externally on the graphene layer of the proposed PCF increases the Sw and SA parameters. It is also exhibited that by increasing the thickness of graphene layers, the confinement loss is enhanced, and the SA is decreased. In addition, by adding the thickness of the MgF2, both SA and confinement loss parameters are increased. The results also show a linear relationship between the parameters with a very high figure of merit (FOM) of 17,416.66RIU⁻¹ and a resolution of 2.5 × 10–5.
... Moreover, d* denotes the lattice-plane spacing for the reciprocal cell and β* represents the integral breadth of the reciprocal lattice point. The magnitude of D is directly indicating the nanoparticle strain [26,27]. ...
... In comparison, the data are estimated by two techniques, a difference is seen between the crystal sizes [27]. The large value of D estimated using the Halder-Wagner method may be attributed to large lattice strains [26]. In both cases, after irradiation and addition of surfactant, the particle size is reduced. ...
... This indicates that the nanoparticles are superparamagnetic at room temperature. This phenomenon is often observed when the size of magnetic particles decreases to the critical diameter [26,34]. Results show that in surfactant-added sample (NF3 in comparison of NF1), the particle size decreases and therefore, the magnetic saturation (M s ) is decreased. ...
In this study, pure and surfactant-added nickel ferrite nanoparticles are successfully synthesized using the co-precipitation method. The prepared samples are investigated before and after irradiation of gamma ray and compared. The linear and nonlinear optical responses, morphological, magnetic, and structural properties are examined using the photoluminescence, ultraviolet–visible spectroscopy, z-scan technique, field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), vibrating-sample magnetometer (VSM), and Raman spectroscopy analysis. The XRD analyses of the samples showed their crystallinity with no significant change after gamma irradiation. The grain sizes of the irradiated and surfactant-added nickel ferrites are decreased. According to the FE-SEM images, the synthesized particles are spherical. Based on the VSM results, the nanoparticles displayed superparamagnetic properties. However, after gamma irradiation and adding the surfactant, the magnetic saturation is reduced. The band gap of unmodified samples is measured in the range of 2.05–3.92 eV before and after gamma irradiation. Moreover, the band gap of the nickel ferrite samples modified with cetyltrimethylammonium bromide-tartaric acid is in the range of 2.07–3.84 eV. The closed- and open-aperture z-scans are used to measure the nonlinear refractive index and absorption coefficient, respectively. Based on analysis and data, our synthesized nanoparticles can be a good candidate for various applications such as hyperthermia, catalysis, and optical switches.
... The estimation of crystallite size and strain components can be derived by analyzing the peak broadening, specifically the full width at half-maximum (FWHM) of the X-ray diffraction (XRD) peaks, through the utilization of the esteemed Williamson-Hall equation [55,56], In the equation, represents the X-ray wavelength (1.5406 Å), gives the position of the diffraction peak, is the strain, D is the crystallite size, and K = 0.94 is the shape factor or Scherrer constant. ...
The current study aims to determine the optimal ferrite composition for a substrate material with good magneto-dielectric properties and low losses in order to fabricate high-frequency miniaturized antennas. Cobalt–zinc ferrite samples with different concentration of zinc were synthesized using the sol–gel method and polyvinyl alcohol as the chelating agent. The lattice constant obtained through experimentation agrees with the one obtained from the suggested cation distribution and Rietveld refinement, indicating that zinc has entered the tetrahedral sites of the spinel structure. A higher zinc concentration was associated with a lower average grain size, ranging from 96.7 to 62.4 nm. The investigation will examine complex permittivity, complex permeability, dielectric and magnetic loss tangents, and AC conductivity in order to evaluate the effects of frequencies between 1 MHz and 2 GHz. The material with the composition Co0.4Zn0.6Fe2O4 exhibits low AC conductivity (1.28 × 10⁻⁶ S/cm), low values of magnetic and dielectric loss tangents (0.047, 0.013) at 100 MHz frequency, and a stable miniaturization factor (n = 4.2) over a broad frequency range of 10 MHz to 1 GHz. The persistent magneto-dielectric behavior and low-loss properties of cobalt–zinc nanoferrite confirm that it is a suitable substrate material for high-frequency antenna design.
... Based on the x equation, strain is obtained from the slope of the cos − 4 sin graph (Fig. 3), while crystal size is calculated from the Y-intercept [27]. The crystal size obtained from the W-H plots increased with the sample order as the calcination temperature increased in the range of 17.48-34.41 ...
Based on the desire to improve material properties, the effects of temperature have begun to be investigated. It was found that for nano-sized powder materials, such as ferrites, the structural properties like crystal structure and grain size, as well as many magnetic and electrical properties depending on them, change with the calcination temperature. Considering these changes, the effect of calcination temperature on the structural, magnetic, and electrical properties of MZA ferrites (Mg 0.75 Zn 0.25 Al 0.2 Fe 1.8 O 4 ) prepared by co-precipitation was investigated in this study. The produced MZA ferrites were calcined at three different temperatures (600, 700, and 800 °C). The X-ray diffraction results showed that the samples exhibited a cubic spinel structure. It was found that the crystal sizes (D_sch) calculated using the Debye-Scherrer equation increased with increasing calcination temperature (22.47, 33.53, and 42.53 nm). From the Williamson–Hall (W–H) plots, crystal sizes were calculated almost same as Debye–Scherrer crystal sizes. The nano-sized particles were examined by scanning electron microscope (SEM). Elemental analysis was performed using EDX. $${\nu }_{1}$$ ν 1 and $${\nu }_{2}$$ ν 2 absorption bands and O–H and C–H vibrations were detected in the FTIR spectra. Magnetic measurements were carried out at room temperature and in the range of ± 60 kOe under the applied field. Magnetic results are explained by superparamagnetism. Dielectric measurements were performed at room temperature and a frequency range of 20 Hz to 10 MHz. The dielectric properties can be explained by Maxwell–Wagner theory. Impedance spectroscopy study revealed that the relaxation mechanism is consistent with the Cole–Cole model. In AC conductivity studies at room temperature, it was found that the sample calcined at 600 °C would be suitable for energy storage devices.
... To produce a physical specimen that is broadening-free, all effects, especially instrumental ones, must be removed. It is worthwhile to study the applicability of preset peak-shape functions in the size-strain analysis because of the great interest there is in accurately modelling peak broadening in the [11][12][13] analysis in terms of physical (size and strain) parameters [14][15][16]. Moreover, the results obtained by the integral-breadth and/or Warren-Averbach analyses were usually not comparable. ...
... One can notice a similar form between this equation and the Halder-Wagner and SSP methods by the appearance of broadening in square form. To verify the deduced model by applying it to different lattice systems, six real XRD patterns for CuO [45], LaFeO 3 [13], Mn 3 O 4 [52], Fe 2 O 3 [53], ZnO [54], and MgO [55] were used. Fig. 6 shows the XRD patterns for theses samples. ...
... Graphene is an ultrathin two-dimensional (2D) carbon nanomaterial with high specific surface area, excellent electrical and thermal conductivity, high charge carrier concentration and electron mobility, and high mechanical performance [1][2][3][4]. These unique properties offer graphene as a promising nanomaterial in various applications, such as energy storage and conversion systems [5,6], sensors [7], and catalysis [8]. ...
The main challenges in polymer composites containing conductive fillers such as reduced graphene oxide (rGO) nano-platelets are proper dispersion of these particles and reduced dissipation of energy due to electrical loss in the bulk of composites. Surface modification is an effective method to address these challenges. However, the proper structure and adequate lengths of grafted alkyl chains and the corresponding changes in electrical properties of the particles before adding to the polymer matrix with desired properties need to be further investigated. In this study, chemical modification of rGO platelets with short and long alkyl chains was carried out to design modified particles (mrGO) with controlled electrical conductivity and dielectric permittivity before incorporating them into a polyacrylic matrix. Alkyl-silanes with chain lengths of 3 and 16 carbon atoms as short chains and poly (butyl acrylate) (PBA) as long chains were grafted on the rGO surface. The successful modification of rGO was evaluated by using Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. Electrical conductivity for mrGOs decreased as the chain length increased, especially for PBA chains, due to a significant reduction in the long-range movement of electrons. Dielectric relaxation spectra of rGOs modified by short chains followed the Drude model, whereas the Debye-type dielectric relaxation was observed for the matrix-free polymer-grafted rGO nanocomposites. Finally, the dielectric properties of acrylic copolymer composites containing 0.5 wt% of mrGOs were examined. Comparing three types of particles, incorporating the polymer-grafted rGO into the polymer matrix resulted in a 47% increase in dielectric permittivity along with a minor increase in dielectric loss, which was less significant in other composites. These composites can be used as high-k materials for energy storage and conversion applications.
... where λ is the X-ray diffraction wavelength (1.5406 Å), θ is the Bragg angle, k is the Scherrer constant and β is the full width at high maximum of the diffraction peak (FWHM) diffraction peak intensity. In addition, the dislocation density (δ s ) and the strain (ε s ) were calculated by the following equations [27,28]: Table 1 summarizes the obtained values of the crystallite size (D s ), the dislocation density (δ s ) and the strain (ε s ) of the CZTS:Na deposited on glass substrates heated to a temperature of 100 °C and annealed in sulfur atmosphere at 400 °C. The prepared sodium-doped CZTS films show an increase in crystallite size (D s ), which was caused by the diffusion of larger radius sodium cations [29]. ...
... The crystallite size can also be estimated from the Williamson-Hall equation [27,32,33]: Table 1 The estimated values of crystallite size (D) and microstrain by different methods, of undoped and Na-doped CZTS thin films grown on substrates heated to 100 °C and annealed in sulfur atmosphere at 400 °C ...
... Another method we have used to estimate average crystallite size D H and the strain value ε H from the XRD data: Halder-Wagner Method [27,[32][33][34][35]. According to this method, the relationship between FWHM, average crystallite size and lattice strain is given by the following formula: ...
Non-doped and sodium-doped Cu2ZnSnS4 (CZTS) thin films deposited on heated glass substrates at 100 °C have been successfully fabricated by the thermal evaporation technique, after what all layers were annealed under sulfur atmosphere at 400 °C. The structural properties of all layers were analyzed using X-ray diffraction and Raman spectroscopy methods. These analysis reveals a polycrystalline with kesterite structure and preferential orientation along the (112) plane for all samples. The surface morphology of all samples was investigated using atomic force microscopy (AFM). The obtained topographies show an improvement of the crystalline quality of post-sulfurized Na-doped CZTS films. Further, the optical measurement recorded by UV–Vis spectroscopy reveals that the direct band gap energy of post-sulfurized Na-doped CZTS films were in the range of 1.56 eV and 1.61 eV. Electrically, all films show p-type electrical conductivity, measured by the hot probe method. In addition, Hall Effect measurements show that Na-doped CZTS thin films exhibit lower resistivity and mobility, as well as higher carrier concentration, than Non-doped films. We can conclude that doping CZTS with Na makes it a better photovoltaic material, and that it is suitable as an absorber layer.
... The bending in the Fe-O-Fe bond has been observed in the VESTA image. The typical crystallite size of the materials can be estimated using Debye-Scherrer's equation [10][11][12] i.e., as = 0.9 ∕Dcos . However, in order to have better knowledge of the crystalline size and strain we have plotted Williamson-Hall's (W-H) plots for our material. ...
In the present article, we report the magnetic, dielectric, and structural properties of the perovskite Bi0.5La0.5Fe0.4Al0.1Mn0.5O3. The structural analysis shows that this system crystallizes in a disordered orthorhombic phase with the space group Pnma. We found two consecutive magnetic transitions at 42 K and 147 K which have been suggested to be associated with the spin-glass and long-range ordering transitions, respectively. Further, temperature-dependent Raman spectra shows that this system has a spin-phonon coupling. Moreover, the dielectric measurement suggests that this system has a large dielectric constant at ambient temperature. Additionally, the dielectric spectrum suggests an unusual frequency-dependent step-like trend and the presence of weak relaxor ferroelectricity in the system. Thus, the presence of such multiple interesting characteristics suggests that Bi0.5La0.5Fe0.4Al0.1Mn0.5O3 can be used as spintronic devices and high dielectric applications.
