This study explored the structural, optical, and dielectric properties of Pure and Mn⁺² doped ZnO nano-particles (Zn_1−xMn_xO) with x ≥ 20%, synthesized by co-precipitation method followed by annealing at 450⁰C. Different characterization techniques were conducted to characterize the as-prepared nano-particles. X-ray Diffraction analysis of the pure and Mn⁺² doped presented a hexagonal wurtzite structure and a decreased crystallite size with increasing doping concentration. Morphological analysis from SEM revealed finely dispersed spherical nanoparticles with particle size of 40–50 nm. Compositional analysis from EDX confirmed the incorporation of Mn⁺²ions in ZnO structure. The Results of UV spectroscopy showed that changing the doping concentration affects the band gap, and a red shift is observed as the doping concentration is increased. The band gap changes from 3.3 to 2.75 eV. Dielectric measurements exhibited decrease in the relative permittivity, dielectric loss factor and ac conductivity by increasing Mn concentration.

In the present study, pure, Co, Gd, and Co/Gd di-doped ZnO nanoparticles were synthesized via the co-precipitation synthesis route. The prepared samples were characterized through different techniques such as the X-ray diffraction method (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, photoluminescence (PL)spectroscopy, and an impedance analyzer and vibrating sample magnetometer (VSM). The XRD pattern shows ZnO’s wurtzite hexagonal crystal structure; moreover, the shifting of characteristic peaks toward the lower angle indicates the inclusion of Co and Co/Gd in the ZnO host lattice. SEM micrographs show various morphologies such as rods, the agglomeration of particles, and spherical nanoparticles. The UV-Vis spectroscopy reveals that the absorption increased in the visible region and there was a substantial redshift for the doped samples. The bandgap decreased from 3.34 to 3.18 eV for the doped samples. The PL spectra show near-edge and inter-band transitions; the origin of inter-band transitions is attributed to the defect states present within the bands. The dielectric constant is strongly frequency dependent and decreases with Co and Co/Gd doping, while the electrical conductivity increases. A VSM study indicates that pure ZnO is diamagnetic, while the Co and Co/Gd doped ZnO nanoparticles showed ferromagnetic behavior. Under UV-visible light irradiation, the Co/Gd-ZnO nanoparticles showed higher photocatalytic activity than the ZnO nanoparticles. The enhanced photocatalytic activity may be attributed to a decreased bandgap with doping.

Polycrystalline compounds of lanthanum strontium manganite (La_1-xSr_xMnO₃, LSMO) are widely used in electronic storage devices due to their minimal losses and electronic charge transport properties. In this study, we investigated how varying substitutions of Sr²⁺ for values of x = 0.0, 0.1, and 0.2 affected the tuning of the optical band gap and dielectric losses in La_1-xSr_xMnO₃ nanoparticles. Synthesized samples were structurally analyzed via X-ray diffraction. A rhombohedral R3¯c crystal structure was confirmed for all prepared samples; crystallite size ranging from 15 nm to 20 nm was estimated along with other lattice parameters. Polygonal or hexagonal-like morphology was revealed by field emission scanning electron microscopy, with a moderate size distribution of nanoparticles affected by thinner grain boundaries in doped LSMO. Energy dispersive spectroscopy was employed to confirm the elemental composition of each compound, and the infrared spectrum indicated bonding in the fingerprint region It was observed that there was a significant reduction in the optical band gap, which was measured using ultraviolet spectrometer absorption data. The band gap decreased from 4.34 eV to 4.11 eV. This reduction was found to be related to the difference in refractive index, which was calculated using both Moss and Herve–Vandamme relations. In parallel, frequency-dependent dielectric analysis revealed that frequency was proportional to the increase in Sr content, inversely affecting dielectric loss. Moreover, the AC conductivity of the prepared samples increased with the rise in Sr content, as described by Johnscher’s universal power law in the region of high frequency.

Pellets of Pure and Fe-doped dilute magnetic semiconducting (DMS) samples are studied for bulk magneto-resistance (BMR) at room temperature and at low-temperatures ∼100K. Raman-, photoluminescence- and X-ray photoelectron-spectroscopic techniques are used to determine chemical and electronic structures of the samples. A broadband intense yellow-green-orange luminescence is observed in Fe-doped ZnO samples and emission red-shifts are investigated. Electrical transport is studied with and without applied magnetic field up to 9T and thermal activation and hopping modes of conduction is discussed in light of nature of Fe substitution in the host lattice. Several decremental- to incremental-BMR crossovers are obtained corresponding to experimental variables of Fe concentration 0.025 ≤ x ≤ 0.1, temperature and applied magnetic field. Several possible modes of magneto-transport are discussed to further elucidate the origin of the as-found BMR crossovers in our samples. Positive BMR in pure- and highly doped (x ≥ 0.1) ZnO is found to originate from F-centers and thermal fluctuations, respectively. However, modestly doped (x ≤ 0.05) ZnO exhibit thermally activated conduction and magnetic poloron mediated negative BMR.

Polycrystalline compounds of lanthanum calcium manganite La_1 − xCa_xMnO₃, (LCMO) are extensively utilized in energy conversion systems because of their low losses and features related to the transfer of electric charges. This work aimed to examine the impact of different levels of Ca²⁺ replacements (x = 0.1, 0.2, and 0.3) on the adjustment of the optical band gap and dielectric losses in La_1 − xCa_xMnO₃ nanoparticles. The synthesized samples underwent structural analysis using X-ray diffraction. All generated samples were proven to have an orthorhombic R\(\bar{3}\)c crystal structure. The estimated crystallite size ranged from 25 nm to 32 nm, and other lattice characteristics were also determined. An agglomerated spherical form consisting of nanoparticles with a range of (33–46 nm) can be seen in the scanning electron micrographs of all of the LCMO samples. The nanoparticles had a moderate size distribution and were influenced by narrower grain boundaries. Energy-dispersive X-ray spectroscopy was utilized to verify the elemental makeup of each chemical, while the infrared spectrum revealed bonding in the fingerprint region. A considerable decrease in the optical band gap was detected through the analysis of UV spectrometer absorption data. The band gap exhibited a reduction from 3.95 eV to 3.74 eV. The decrease was determined to be associated with the disparity in refractive index, which was computed using both Moss and Herve-Vandamme equations. Simultaneously, frequency-dependent dielectric study indicated a direct correlation between frequency and the rise in Ca concentration, resulting in an inverse impact on dielectric loss. In addition, the electrical conductivity of these nano-system that were created design as the Ca content grew. This increase was represented by Johnscher’s universal power law in the high frequency range.

We will discuss the development of a new ternary and quaternary tellurium telluride chalcogenide nanoparticles used for efficient thermo-electric waste heat energy convertor called thermo-electric generator. Nanoparticles-based tellurium telluride chalcogenide nanoparticles, which will be used for thermoelectric generator, will eventually solve an important issue of the energy crises, that is, conversion of waste heat into useful electrical energy. By injecting charge carriers in the host matrix of Tl10-x-yAxByTe6 nanomaterials system, different types of dopants (A = Pb, Sn, Ca and B = Pb, Sb Sr, etc.), with x = 0–2.5 and y = 0–2.5 on tellurium telluride has been introduced to synthesize new materials by Co-precipitation techniques and also by solid state reaction techniques followed by Ball-Milling for the fabrication of nanomaterials. We will study the effect of reduction of charge carriers in thermal and transport properties using different dopants contents by replacing host atoms. The charge carrier’s concentration will affect the ratio of electron-hole concentration which in turns increases the electron scattering in these chalcogenide nanoparticles, which will affect the electrical conductivity and thermo-power. The prime purpose of doping with different ionic radii and different concentration is to enhance the power factor for the tellurium telluride nanosystem. At the end one will be able to control different physical parameters such as, thermally assisted electrical conductivity, and thermopower. Different characterization technique will be applied, for example, X-Ray diffraction techniques will be used for structural analysis, SEM will shows the morphological structure of the particles at 100 nm and energy dispersive x-rays spectroscopy will be used for elemental analysis. The electrical conductivity will be measured by four-probe resistivity measurement techniques, and Seebeck coefficient will be measured by standard temperature gradient techniques.