Narrow Results

The composite (PPy/CuO) films are created using the solution casting solution method by mixing the polymer polypyrrole (PPy) with copper oxide nanoparticles (CuONPs) at different concentrations of CuO (4%, 6% and 8%). The XRD confirms the effective fabrication of the composite (PPy/CuO). The impact of CuO on the optical and structural characteristics was studied. The addition of CuO enhances the refractive indices ($n_o)$ of PPy from 1.42 for pure PPy to 1.55 for PPy with 4% CuO, and further to 1.69 for PPy with 8% CuO. The dispersion energy of pure polypyrrole (PPy) is 4.55eV, which increased to 5.31eV when doped with 4% CuO. Furthermore, the increasing of CuO concentration to 6% and 8% resulted in higher dispersion energies, respectively, of 5.87 and 6.14eV. The oscillation energy $E_0$ decreased from 4.43eV for PPy to 3.76, 3.41 and 3.25eV for PPy/4%CuO, PPy/6%CuO and PPy/8%CuO, correspondingly. The introduction of CuO into the PPy polymer results in modifications to its optical characteristics. Additionally, there was an observed rise in the plasma frequency from $0.04\times 10^{14}$${\text{s}}^{-1}$ for PPy to $0.14\times 10^{14}$${\text{s}}^{-1}$ for PPy/8%CuO. The findings of this study offer empirical support for the possible use of PPy/CuO films in optical devices.

The motivation behind this study is to fabricate novel nanocomposite materials with stronger dielectric characteristics to be applied in electronic devices. The chemical oxidative polymerization technique was employed to fabricate the PET/(PPy-Ag) polymer composite films. These films consist of silver nanoparticles (AgNPs) and polypyrrole (PPy), and the blend (PPy-Ag) is then deposited on the polyethylene terephthalate (PET) substrate. The choice of method depends on the desired application, the properties of the polymer and the level of nanoparticle dispersion required. The characterization methods, Fourier-transform-infrared spectroscopy (FTIR) and energy dispersive X-ray (EDX) were utilized in this study. The EDX data show that the PET/(PPy-Ag) is successfully fabricated with elements C, N, O and Ag, with weight ratios of 15.76%, 8.92%, 65.88% and 9.44%, respectively. The influence of (PPy-Ag) on the conductivity and surface wettability of PET was evaluated. The surface-free energy and adhesion work were determined using contact angle measurements. The surface-free energy increased from 41.64 to 60.24mJ/m² and the water adhesion work increased from 98.78mJ/m² for PET/(PPy-Ag)-1 to 121.01mJ/m² for PET/(PPy-Ag). Moreover, the conductivity enhanced from $6.2\times 10^{-9}$S.cm${}^{-1}$ for PET to $2.4\times 10^{-6}$S.cm${}^{-1}$ for (PPy-Ag)/PET. By modifying the properties of the composite PET/(PPy-Ag), the results demonstrated that the fabricated composite can be used as an electronic and industrial device.

In this study, the composite P(4ClAni)/CuO, which consists of Poly(4-Chloroaniline) P(4ClAni) and copper oxide (CuO) nanoparticles, was successfully synthesized utilizing a chemically oxidative polymerization approach to be applied in optoelectronics. Both FTIR and EDX analyses showed that CuO has been successfully integrated into the P(4ClAni) matrix. The SEM micrographs reveal uniform loading and distribution of CuO throughout the P(4ClAni) polymeric chains. The UV–Vis absorbance, the Urbach energy, the band edge and a number of carbon clusters were determined. The Tauc relationship was used to determine the band gaps, which revealed a decrease as the CuO concentration increased. The band gap drops from 3.84eV for P(4ClAni) to 3.09, 2.85, and 2.64eV, correspondingly for P(4ClAni)/CuO-1, P(4ClAni)/CuO-2, and P(4ClAni)/CuO-3. While, the Urbach tail is increased from 1.66eV for P(4ClAni) correspondingly to 1.81, 1.85, and 1.93eV. The results show composites made of P(4ClAni)/CuO have better optical characteristics than pure polymer P(4ClAni), suggesting that they can use these composites in optoelectronics devices.

Flexible polymer nanocomposite composed of organic methylcellulose (MC) and semiconducting titanium dioxide (TiO₂) films were successfully prepared. The energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) recorded the structure characteristics of the films, proving that MC/TiO₂ nanocomposite were successfully synthesized. The EDX showed that this composite was composed of (28.55% C, 50.90% O, and 20.55% Ti), which displayed the chemical composition of MC/TiO₂. Moreover, the scanning electron microscope (SEM) shows the TiO₂ nanoparticles are loaded homogenously in the nanocomposite films. With increasing the TiO₂, the FTIR intensity of most peaks gradually decreased which may be attributed to that titanium dioxide nanoparticles (TiO₂ NPs) were formed on the methylcellulose (MC). The UV spectrophotometer records the data of absorption (A) for the MC and MC/TiO₂ films between 200nm and 1100nm at the ambient temperature. Using Tauc’s relation, the linear/nonlinear optical characteristics of MC and MC/TiO₂ films were computed. By mixing MC with 2%, 4%, and 6% TiO₂, the Urbach energy of the MC is enhanced from 1.77eV to 1.85, 2.02, and 2.34eV, correspondingly, while the TiO₂ reduced the energy gap of MC from 5.17eV to 3.59, 3.52, or 3.43eV. Moreover, the carbon cluster increased from 44 for MC to 92, 95, and 101 for MC mixed by 2%, 4%, and 6% TiO₂. This study found the MC/TiO₂ hybrid films can potentially be used as optical materials for flexible electronic devices.

Raman scattering analysis revealed that the structure of carbon films prepared by pulsed laser deposition (PLD) at room temperature is predominantly amorphous and the structure of amorphous carbon nitride (a-CN_x) thin films can be changed with varying substrate temperatures (ST) from 20°C to 500°C. The deposited a-CN_x films are composed of C–N, C≡N and C–O bonded materials and the C–N and C≡N bonds are increased with ST. We have found that no other obvious peaks can be distinguished in the range 900–2300 cm^-1 in which several peaks always appear in a-CN_x films. The spectra were deconvoluted into Raman D and G peaks and the structural parameters are determined. The upward shifts of the Raman G peak towards 1592 cm^-1 shows the evidence of a progressive formation of crystallites in a-CN_x films upon increase of ST. While the upward shifts of the Raman D peak towards 1397 cm^-1 have been related to the decrease of bond-angle disorder and sp³ tetrahedral bonding in its structure. Raman FWHM and I_D/I_G also indicate that N incorporation with increase of ST caused an increase in the number and/or size of graphitic domains in the a-CN_x films.

When one cuts himself, it is amazing to watch how quickly the body acts to mend the wound. Immediately, the body works to pull the skin around the cut back together. The concept of repair by bleeding of enclosed functional agents serves as the biomimetic inspiration of synthetic self repair systems. Such synthetic self repair systems are based on advancement in polymeric materials; the process of human thrombosis is the inspiration for the application of self healing fibres within the composite materials. Results based on flexural 3 point bend test on the prepared samples have shown that the doubled layer healed hollow fibre laminate subjected to a healing regime of 3 weeks has a healed strength increase of 27% compared to the damaged baseline laminate. These results gave us confidence that there is a great potential to adopt such self healing mechanism on actual composite parts like in aircraft's composite structures.

Polycrystalline cobalt substituted Ni–Zn ferrite with composition Ni_0.65-xCo_x Zn_0.35Fe₂O₄(x = 0.00–0.25 insteps of 0.05) have been prepared through the conventional solid state ceramic method. Calcination and sintering have been performed in air atmosphere at 950°C and 1250°C for 4 h and 2 h, respectively followed by natural cooling to room temperature. X-ray diffraction patterns of all samples indicated the formation of the single spinel structure and the accurate lattice parameter for each composition has been determined using the Nelson–Riley error function. The increase in lattice constant on cobalt substitution is attributed to the ionic radius difference between the displaced and the substituted ion. The variation in lattice constant on incorporation of Co²⁺ ion indicates its solubility into the spinel lattice and noticeable modification in structural properties have been observed. The observed increase in the saturation magnetization and Curie temperature with the increase in the Co²⁺ substitution is due to its higher magnetic moment compared to that of Ni²⁺, improvement in the A–B exchange interaction mechanism and large positive contribution to magnetic anisotropy due to presence of Co²⁺ when they are at the octahedral sites. The observed variation in the initial magnetic permeability and the magnetic loss factor with cobalt substitution measured at a low frequency of 1 KHz have been attributed to the modification in the density, porosity, grain size and anisotropy contributions. A nearly comparable variation is observed in the room temperature dc electrical resistivity and activation energy for conduction and is attributed to the modification in structure, role and nature of cobalt ions and the microstructure aspects like grain size and pore concentration. The activation energy values in the range of 0.28 to 0.36 eV suggest a possible electron hopping. The observed changes in the structural and the magnetic and electrical properties have all been discussed in the light of exiting understanding.

We have studied the structural, electronic and dynamic properties of γ-Li₄SiO₄ (lithium orthosilicate) using density functional theory (DFT) with the generalized gradient approximation (GGA). The crystal structure is fully relaxed. The electronic band structure and Density of States (DOS) calculations indicate that γ-Li₄SiO₄ is an insulator with an indirect band gap of 5.19 eV and it has a conduction band with the width of 5.92 eV and two valance bands with the width of 4.45 eV and 0.57 eV, respectively. In the partial DOS, Li and Si electronic densities increase more sharply than O atoms. Comparing with previous works, the phonon dispersion curves without negative frequencies are calculated along high symmetry points. By adding the Born effective charges in the phonon calculation, the LO–TO splittings are also calculated which indicate that γ-Li₄SiO₄ is polar and anisotropic. The optical modes of phonon frequencies at Γ point are assigned as Raman and Infrared-active modes. Additionally, the thermodynamic functions (entropy, internal energy, Helmholtz free energies and constant-volume specific heats) were determined by using the phonon DOS. The calculated results may provide useful guidance of γ-Li₄SiO₄ for future experimental studies in some degree.

Bismuth telluride (Bi₂Te₃) is one of the most intricate materials with its semiconducting, insulating and pressure-induced superconducting properties. Although different theoretical works have been carried out to understand the confusing properties of Bi₂Te₃, information about the high pressure structural, elastic, mechanical and phonon properties of this significant material is still rare. Unlike earlier theoretical approaches, two-body interatomic potentials in the Morse potential form have been employed for the first time to predict the density, phase transition pressure, elastic constants, bulk, shear and Young moduli and elastic wave velocities of Bi₂Te₃ under pressures up to 12 GPa. $\alpha \to \beta$ phase transition pressure of Bi₂Te₃ was found to be 10 GPa. The results of above elastic quantities agree well with experiments and are better than some of the published theoretical data. In addition, the effect of pressure on the phonon dispersion and density of states (DOS) were also evaluated with the same potential and their results are satisfactory, especially for the low-frequency acoustic portions of phonons.

Detailed first-principle calculations of properties in zinc blende quaternary alloy ${\mathrm{\text{B}}}_x{\mathrm{\text{Al}}}_y{\mathrm{\text{In}}}_{1-x-y}\mathrm{\text{N}}$ at various concentrations are investigated using density functional theory (DFT) within virtual crystal approximation (VCA) implemented in alchemical mixing approximation. The calculated bandgaps show direct transitions at $\mathrm{\Gamma }$–$\mathrm{\Gamma }$ and indirect transitions at $\mathrm{\Gamma }$–$X$, which are opened by increasing boron concentration. The density of state (DOS) revealed upper valence band (VB1) domination by $p$-states atoms, while $s$-states dominate the lower valence band (VB2); also, the DOS shows the contribution of $d$-states to the conduction band. The first critical point in the dielectric constant ranges between 0.07–4.47 eV and is due to the first threshold optical transitions in the energy bandgap. Calculated static dielectric function (DF) ${𝜖}_1(0)$ is between 5.15 and 10.35, an indication that small energy bandgaps yield large static DFs. The present results indicate $\mathrm{\text{ZB}}$-${\mathrm{\text{B}}}_x{\mathrm{\text{Al}}}_y{\mathrm{\text{In}}}_{1-x-y}\mathrm{\text{N}}$ alloys are suitable candidates of deep ultraviolet light emitting diodes (LEDs), laser diodes (LDs) and modern solar cell since the concentrations $x$ and $y$ make the bandgap and lattice constant of $\mathrm{\text{ZB}}$-${\mathrm{\text{B}}}_x{\mathrm{\text{Al}}}_y{\mathrm{\text{In}}}_{1-x-y}\mathrm{\text{N}}$ quaternary alloys tunable to desirable values.

We report a systematic theoretical study of Pt${}_{1-x}$Pd${}_x$ alloys using ab initio density functional theory (DFT) by pseudo potential method. We have used super cell approach to investigate structural, electronic and thermal properties of Platinum (Pt), Palladium (Pd) and their alloys Pt${}_{1-x}$Pd${}_x$($x$ = 0.00, 0.25, 0.50, 0.75, 1.00). The calculated lattice constants and bulk moduli are in good agreement with available literature data. The results of electronic properties revealed that the alloys are metallic in nature. The thermal properties were investigated through density functional perturbation theory (DFPT) and quasi-harmonic approximation. The contribution to the free energy from the lattice vibration was calculated using the phonon densities of states (DOS) derived by means of the linear-response theory. The DFPT with quasi-harmonic approximation methods was applied to determine the phonon DOS and thermal quantities i.e., the Debye temperatures, vibration energy, entropy and constant-volume specific heat.

The structural, electronic, magnetic properties of Mn₃XC (X=Al, Zn and Ga) antiperovskites have been investigated using first principles calculations based on Full-Potential Linearized Augmented Plane-Wave (FP-LAPW) method. Generalized Gradient Approximation with parameterization by Perdew (GGA-PBESol) is used to take into account the electron exchange–correlation interaction. Structural optimization is performed by fitting calculated data (energy-volume) to Birch–Murnaghan equation of state. Lattice constants increase in the order Mn₃AlC$\to$Mn₃GaC$\to$Mn₃ZnC. Electronic results show that there is no bandgap near the Fermi level. While the magnetism in these compounds is derived mainly from Mn atom. Finally, thermodynamic properties, including bulk modulus, heat capacities, thermal expansion and Grüneisen parameter, are computed using quasi-harmonic Debye model and analyzed in detail.

The computational predictions of transition-metal tri-chalcogenide (TMTCs) were performed using ab initio density functional theory (DFT) to investigate the electronic band structure, the partial density of states (PDOS), optical absorptions, dielectric functions, complex conductivity, reflectivity, refractive index, electron loss, the Poisson’s ratio, Young’s modulus, bulk-to-shear ratio, and phonon dispersion. The bandgap is measured from the valence band maximum (VBM) to the conduction band minimum (CBM) with the G–Z transitions. This suggests that the material is an indirect bandgap semiconductor. The electronic bandgap ($E_g)$ is significantly improved with nonlocal hybrid functionals, especially in HSE0s, with $E_g$ of 1.0eV, which is in excellent agreement with the experimental data. However, our data shows that the HF-LDA exchange correlations significantly overestimate the $E_g$ with 7.33eV. Also, our optical absorption data indicates a high absorption coefficient of about $2.9\times 10^5$cm${}^{-1}$. The absorption peak of 7.4eV indicates TiS₃ can be applied in vacuum ultra-violet (VUV) applications. The reflectivity is also shown to be high, with over 90% of light being reflected. The mechanical stability of the monoclinic system can be testified by our elastic coefficients and the phonon dispersions.

Ni-doped molybdenum disulfide (MoS${}_2)$ powders at 1%, 2%, 3%, 4%, 5% and 7% of Ni are prepared by the hydrothermal method. Sophisticated analytical studies such as X-ray diffraction, Raman, TEM and photoluminescence (PL) were analyzed to predict their structural, morphological and optical properties. Effects of Ni-doping with MoS₂ on crystalline structure, morphology as well their optical phenomenon were examined in detail. Ni doping on MoS₂ revealed tetragonal crystal structure of the parent compound. A significant decrease in their optical energy gap (from 1.86 to 1.76eV) was perceived with Ni doping concentration increment. PL intensity exhibited a considerable improvement with Ni-doped MoS₂ samples at room temperature. From a theoretical viewpoint, the compact density matrix method is applied for Ni–MoS₂ to calculate their linear and nonlinear absorption coefficients as well as refractive index modulations for undoped and Ni-doped samples at the focal points of their corresponding intra-band and inter-band transitions. Observed findings are well correlated with the practical results which prove that Ni–MoS₂ layers are promoters for potential applications in optoelectronic technology.

In this paper, using density functional theory (DFT), we present a systematic computational investigation on ZrCl₄ in respect of electronic, structural, optical, mechanical properties, which is of great interest in semiconductor physics. Our results show that the metal tetrachloride is a mechanically stable semiconductor with a wide indirect bandgap of $E_g^{\mathrm{\text{HSE}}03}=4.82$eV ($E_g^{\mathrm{\text{GGA}}}=3.56$eV). ZrCl₄ could behave as a brittle material and could be covalent. According to our optical data, a reflectivity of 27.6% could suggest a good material absorption characteristic on the studied material, with a high absorption coefficient of up to $1.61\times 10^5$cm${}^{-1}$. On the partial density of states plot, the hybridization of electron orbitals between Cl 3p⁵ states in the valence band and transition Zr 4d² states in the conduction band is also observed. Our findings advance the fundamental understanding of ZrCl₄ material and provide important insights in electronic/optoelectronic applications.

Vanadium oxide thin films were grown on glass substrates using spray pyrolysis technique. The effects of substrate temperature, vanadium concentration in the initial solution and the solution spray rate on the nanostructural and the electrochromic properties of deposited films are investigated. Characterization and the electrochromic measurements were carried out using X-ray diffraction, scanning electron microscopy and cyclic voltammogram. XRD patterns showed that the prepared films have polycrystalline structure and are mostly mixed phases of orthorhombic α-V₂O₅ along with minor β-V₂O₅ and V₄O₉ tetragonal structures. The preferred orientation of the deposited films was found to be along [101] plane. The cyclic voltammogram results obtained for different samples showed that only the films with 0.2 M solution concentration, 5 ml/min solution spray rate and 450°C substrate temperature exhibit two-step electrochromic properties. The results show a correlation between cycle voltammogram, morphology and resistance of the films.

In this research, rod-like undoped and Zn doped h-MoO₃ thin films were grown on top of MoO₃ seed layers, using hydrothermal technique without adding any surfactant. Seed layers of MoO₃ were coated on top of glass substrates using spray pyrolysis technique. Structural, morphological and optical properties of thin films were examined. XRD pattern analysis showed that the seed layer has orthorhombic crystal structure. Also, it confirms the formation of hexagonal structure for thin films grown by hydrothermal. FESEM images show the formation of long, well-shaped hexagonal rod-likes. UV-Vis spectroscopy reveals band gap increasing from 3.2 eV to 3.54 eV, by increasing Zn.

Manganese substituted nickel–copper–cobalt ferrite nanoparticles having the basic composition ${\mathrm{\text{Ni}}}_{0.2}{\mathrm{\text{Cu}}}_{0.2}{\mathrm{\text{Co}}}_{0.6-x}{\mathrm{\text{Mn}}}_x{\mathrm{\text{Fe}}}_2{\mathrm{\text{O}}}_4$ (x = 0.0, 0.1, 0.2, 0.3 and 0.4) were synthesized by sol–gel auto-combustion method. X-ray diffraction (XRD) was used to estimate phase purity and lattice symmetry. All the prepared samples show the single-phase cubic spinel structure. Fourier transform infrared (FTIR) measurements also confirm the cubic spinel structure of the ferrite that is formed. The preparation of samples show these nearly spherical particles by Transmission electron microscopy (TEM). The magnetic properties of Mn${}^{2+}$ ion substituted in nickel–copper–cobalt ferrite were studied by Vibrating sample magnetometer (VSM). The saturation magnetization ($M_s$), remanent magnetization $(M_r)$, coercivity $(H_c)$, magnetic moment $({\mu }_B)$ and anisotropy constant $(K)$ first increase and then decrease with the increase of ${\mathrm{\text{Mn}}}^{2+}$ ions content. They had better magnetism than pure sample and other substituted samples when the substitution amount of ${\mathrm{\text{Mn}}}^{2+}$ ions was $x=0.1$. At $x=0.1$, the maximum values of remanent magnetization $(M_r)$, saturation magnetization $(M_s)$ and coercivity $(H_c)$ are 25.58 emu/g, 61.95 emu/g and 689.76 Oe, respectively. This indicates that the magnetism of ferrite can improve by substituting with the appropriate amount of manganese. However, due to the excess ${\mathrm{\text{Mn}}}^{2+}$ ions instead, ferrite magnetism is weakened. This means that these materials can be used in magnetic data storage and recording media.

In order to study the effect of sintering temperature on the structure and magnetic properties of nickel-magnesium-cobalt ferrite, ${\mathrm{\text{Ni}}}_{0.2}{\mathrm{\text{Mg}}}_{0.2}{\mathrm{\text{Co}}}_{0.6}{\mathrm{\text{Fe}}}_2{\mathrm{\text{O}}}_4$ spinel ferrite with different sintering temperatures (500${}^{\circ }$C, 600${}^{\circ }$C, 700${}^{\circ }$C, 800${}^{\circ }$C, 900${}^{\circ }$C and 1000${}^{\circ }$C) was prepared by sol–gel method. The magnetic properties of the prepared samples were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Vibrating sample magnetometer (VSM). The results show that the sintering temperature has a significant effect on the structure and magnetic properties of nickel-magnesium-cobalt ferrite. Analysis of the XRD pattern confirmed that all samples showed a single-phase cubic spinel structure. The particle size of the prepared sample determined by the Scherrer equation was 51 nm to 135 nm. As the sintering temperature increases from 500${}^{\circ }$C to 1000${}^{\circ }$C, the intensity of all peaks gradually increases, the crystallinity and particle size of the sample increase significantly, but the coercive force decreases, the saturation magnetization, the residual magnetization and the squareness $(M_r/M_s)$ increase first and then decrease. Compared with other samples, the 800${}^{\circ }$C sintered samples had the highest saturation magnetization (59.03 emu/g), remanent magnetization (30.65 emu/g) and squareness (0.519). The increasing peak height of $dM/dH$ at $H_m$ indicates that the cubic spinel structure samples have good crystallinity and magnetic stability.

In this paper, aluminum-doped Ni–Cu–Co ferrite nanomagnetic material powder was prepared by sol–gel technique using citric acid as a complexing agent and high-purity nitrate as raw material. The effect of doping amount of different Al${}^{3+}$ ions on the structure and magnetic properties of ferrites has been studied. The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Energy dispersive X-ray (EDX) and Vibrating sample magnetometer (VSM) were used to characterize the structural and magnetic properties of ferrite. The XRD analysis showed that all samples of Ni–Cu–Co ferrites have a single-phase cubic spinel structure. Average crystallite size was calculated by the Debye–Scherrer formula and it was found that the average crystallite size of the sample was affected by the doping concentration. As the amount of Al${}^{3+}$ ion doping increases, the crystallite size decreases from 54.88 nm to 46.09 nm. The absorption peak of Fourier transform infrared spectroscopy (FTIR) at 590 cm${}^{-1}$ further indicates the formation of cubic spinel structure of Ni–Cu–Co ferrite. Transmission electron microscopy (TEM) images show the presence of particles which are spherically cubic-shaped particles. The constituent elements of the samples were analyzed by EDX spectroscopy. In addition, the ferromagnetism of the samples was confirmed by VSM measurements. The saturation magnetization (Ms) and remanent magnetization (Mr) first increase and then decrease when the aluminum ion concentration increases. Compared with pure samples and other doped samples, they have the best magnetic properties when the doping amount of Al${}^{3+}$ ions is $x=0.05$. It also shows that the prepared samples are suitable for magnetic recording materials.