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Ni1-xGdxFe2O4 (x=0.02, 0.04, 0.06 & 0.08) (NGF) nanoparticles were synthesized via hydrothermal method. The X-ray diffraction study confirmed the single-phase cubic spinel structure. The morphology indicated the stones (approximately nanocubes) like structures in the FESEM images. The mass loss, and thermal transition temperatures were evaluated as a function of Gd-content using TG-DTG, and TG-DSC measurements. The M-H loops evidenced the high magnetization values for NGFO as compared to pure nickel ferrite. Cation distribution showed the preferred occupancy of cations in the magnetic spinel system. Frequency dependence of dielectric, conductivity, and impedance parameters was elucidated with increase in Gd-content.

The solid solution of Pb1-x Sm2x/3 (Zr0.6 Ti0.4) O3 ceramics with x = 0.1, 0.2, 0.3, and 0.4 was prepared via the high-energy ball milling technique. Further, the effect of excessive Sm2O3 substitution at Pb-site on structural, dielectric, and dc-conductivity properties was studied. The X-ray diffraction (XRD) analysis confirmed that all samples were crystallized with perovskite and pyrochlore diphase form. Excess Sm3+ substitution in the PZT system increases the pyrochlore volume fraction from 5 to 20% and induces a structural phase transition from rhombohedral to a tetragonal structure. The microstructural study by TEM and SEM indicated that the particles were spherical with an average size of 43–55 nm. The frequency and temperature-dependent dielectric constant for all compositions was carried out and it is obtained that the dielectric constant decreases with Sm3+ content. The phase transition temperature first decreases up to x = 0.2 and then increases for the higher concentration of samarium. The dc-conductivity studies revealed that all samples showed an unusual mixed TCR effect (both positive and negative temperature coefficient of resistance). Such properties of the studied samples indicate that the material is suitable for potential applications in thermistors, and temperature sensors of the automotive, and petroleum industries.

(1-x) (Al0.2La0.8TiO3) + (x) (BiZnFeO3) (x = 0.2–0.8) [ALTBZFO] nanocomposites were synthesized via hydrothermal method. These nanocomposites are significantly adequate for perfect absorber and high charge stowed capacitor applications. The hydrothermal method is mainly a solution reaction involved methodology to control the morphology of the materials, significantly can control the compositions of nanomaterials through multiphase chemical reactions. The X-ray diffraction patterns indicated the phase transformation from tetragonal for x = 0.2 to cubic for x = 0.4–0.8 samples, respectively. The surface morphology showed the existence of nanospheres-like structures. At 1 MHz frequency also, the dielectric constant was increased from 230 to 710 for x = 0.2–0.6 samples, respectively. Interestingly, x = 0.6 nanocomposite exhibited the negative dielectric behavior having the dielectric constant (e′) ~ − 58.5 and dielectric loss (e") ~ − 417 at 8 MHz. Similarly, x = 0.6 sample showed ac-electrical conductivity (σac) − 0.159 S/cm at 6 MHz. Hence, these kinds of materials can provide high charge stored capacitors and perfect absorber applications.

In recent years, the perovskite solar cells have gained much attention because of their ever-increasing power conversion efficiency (PCE), simple solution fabrication process, flyable, light-weight wearable and deployable for ultra-lightweight space and low-cost materials constituents etc. Over the last few years, the efficiency of perovskite solar cells has surpassed 25% due to high-quality perovskite-film accomplished through low-temperature synthesis techniques along with developing suitable interface and electrode-materials. Besides, the stability of perovskite solar cells has attracted much well-deserved attention. In this article we have focused on recent progress of the perovskite solar cells regarding their crystallinity, morphology and synthesis techniques. Also, demonstrated different layers such as electron transport-layers (ETLs), hole transport-layers (HTLs) and buffer-layers utilized in perovskite solar-cells, considering their band gap, carrier mobility, transmittance etc. Outlook of various tin (Sn), carbon and polymer-based perovskite solar cells and their potential of commercialization feasibility has also been discussed.

(1−x) (Al0.2La0.8TiO3) + (x) (CuTiO3) (x = 0.2–0.8) [ALTCT] nanocomposites were prepared through hydrothermal process. The diffraction study indicated the formation of tetragonal structure expressing maximum intense peak at ~ 25.586o for all samples. Lattice constants a = b and c values were found to be increasing from 3.774 to 3.780 A, and 9.394–9.950 A, respectively as a function of ‘x’. The surface morphology showed that the formation of nanospheres, and hexagonal nanorods. Further, the dielectric behavior was studied, and the results showed space charge effect, dielectric relaxation dynamics, and frequency-dependent dielectric properties. Impedance and dielectric modulus formalism was carried out to elucidate the microstructure, polarization, and electrical conduction mechanism.

The Al0.8GdyLa0.2-yTiO3 (y = 0.01–0.04)/AGLT nanoflowers were synthesized via the hydrothermal method. X-ray diffraction patterns showed the polycrystalline nature of AGLT samples, wherein the maximum intense peak was recorded at 13.472°. The surface morphology revealed the nanoflowers, nanospheres, and nanorods like structures for all samples. Furthermore, the optical band gap (Eg) was determined using UV–Visible spectra. The FTIR spectra indicated the existence of metal oxide bonds and other functional groups. The colossal dielectric behavior was observed for y = 0.01 content. The dielectric modulus and impedance spectroscopy properties were elucidated as a function of frequency and composition.

Natural fibers have grown extensively during the last few years and have become interesting to scientists and researchers as an alternative preference for wood dust fiber composites. As they have good mechanical properties, cost adequacy, non-abrasiveness, high particular quality, eco-accommodating, and biodegradability features. They are abused as a trade for traditional fibers like carbon and glass. In present correspondence, the study on the preparation and characterization of a new arrangement of green composites, including Tectona Grandis wood flour fiber as a strengthening material in polymer grid based on epoxy resin has been accounted. The stable mechanical properties of erratically orientated personally blended Tectona Grandis wood flour fiber-reinforced polymer green composites such as tensile, compression, and hardness properties were explored as a purpose of fiber loading. The reinforcement of resin with Tectona Grandis wood dust fiber is accomplished in particulate fiber by employing optimized resin. These fibers were blended with epoxy resin in diverse fortification strengthening percentages. The outcome of the above said mechanical properties were measured. It has demonstrated a development in these stable mechanical properties after reinforcement by fibers. The estimation of static mechanical properties will increment in an increasing percentage of reinforcement. The average ultimate tensile strength is 17.50 MPa, and the compression strength is 246.93 MPa. The microstructural behavior of these composites is studied with the help of scanning electron microscopy (SEM), and the moisture absorption test is also carried out.

The current study highlights the design and construction of a sensitive and selective sensor for detection of dopamine and tyrosine using a GO-SnS2 quantum dots by a drop casting method on glassy carbon electrode. Highly porous nano-crystalline GO-SnS2 quantum dots were synthesized by using ultrasonication followed by hydrothermal method in a facile manner. XRD, SEM, XPS, TEM, and pore size distribution techniques were used to characterize the quantum dots that were produced. The newly fabricated electrode was evaluated for EIS (Electrochemical impedance spectroscopy), CV (cyclic voltammetry) and chronoamperometric methods. The observed limit of detection of dopamine was observed to be 26 nM. High selectivity and sensitivity were observed for electrochemical detection of dopamine and tyrosine.

Spinel ferrite nanoparticles are widely studied to evaluate their suitability in many applications. Magnetic, electrical, optical, and catalytic properties of spinel ferrites nanoparticles depend on: i) intrinsic property such as cation distribution among tetrahedral (A-site) and octahedral ligand (B-site) sublattices in spinel structure and ii) extrinsic properties such as specific surface area and particle size distribution of nanoparticles. To enhance the above properties by modifying both the intrinsic and extrinsic parameters, narrow size distributed Mg0.7Zn0.3Fe2O4 mixed spinel ferrite nanoparticles are synthesized by the solvothermal reflux method using high boiling point reflux solvents. The particles are crystallized in a cubic spinel structure and are single crystallites with an average particle diameter of 12 nm, measured from an electron micrograph. The temperature-dependent dielectric constant $(\varepsilon^{\prime})$ and dielectric loss $(\varepsilon^{\prime \prime})$ of the sample show no change below 290 °C and increase with temperature up to 450 °C. Both $\varepsilon^{\prime}$ and $\varepsilon^{\prime}$ decrease with the increase of electric field frequency and shows dominant space charge polarization at grain boundaries. The DC conductivity estimated from impedance spectra (Cole–Cole plot) shows the Arrhenius model electron hopping conductivity mechanism above 390 °C. Nanoparticles show high Ms (57.41 emu/g) than that synthesized by other methods. The sample shows the magnetic hyperthermia value of 189 W/g at 1 mg/mL concentration. The sample degraded 95% of rhodamine B dye in water in 320 min under UV light illumination. Some of these properties are superior to Mg0.7Zn0.3Fe2O4 nanoparticles synthesized by other wet chemical and/or ball milling methods.

The Ni0.2Mg0.8-xZnxFe2O4 (x = 0.0, 0.2, 0.4, 0.6 & 0.8) nanomaterials were prepared via sol-gel technique. These samples were calcined at three different temperatures (T) such as 400, 450 and 500 °C/5 h. Furthermore, the X-ray diffraction (XRD) patterns of all the calcined samples revealed the single phase cubic spinel structure. The lattice constants (a = b = c) were noticed to be increasing with increase of ‘x’. The grain shape, size and distribution of x = 0.0–0.8 contents were analyzed using field emission electron microscope (FESEM). The x = 0.2 content provided higher optical band gap energy (Eg) value than the remaining contents. Furthermore, the magnetization versus magnetic field (M − H) curves indicated the superparamagnetic nature of x = 0.0–0.8 contents. The high saturation magnetization (Ms) was noticed for x = 0.4 and 0.6 contents. In addition, the distribution of cations like Ni+2, Mg+2, Zn+2, Fe+3 and Fe+2 was performed between the tetrahedral (A) and octahedral (B) sites. The frequency dependence of dielectric constant (e′), dielectric loss (e") and ac-electrical conductivity (σac) was investigated as a function of composition. Moreover, the temperature variation of e′ showed the decreasing trend of dielectric transition temperature (Te) with increase of ‘x’. The high e′ of 163.1 (at 1 MHz) was noticed at x = 0.2 content calcined at 500 °C. Using the power law fit applied to the log σac-log ω plots, the dc-electrical conductivity (σdc) and exponent (n) parameters were calculated.

A series of 1 − x (Al0.2La0.8TiO3) + x (BaTiO3) (x = 0.2, 0.4, 0.6, and 0.8)/ALTBT nanocomposites were prepared via the hydrothermal technique at 150 °C/6 h. The phase identification and structural transformation from tetragonal to cubic were confirmed using the X-ray diffraction pattern (XRD). Particularly, the low BaTiO3 contents (x = 0.2 and 0.4) revealed the tetragonal structure, while the high BaTiO3 contents (x = 0.6 and 0.8) showed the predominant cubic phases. Furthermore, the nanorod-like surface morphology was evidenced from the field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The optical properties ensured the presence of metal oxide (M–O) bonds and wide optical bandgap (Eg ~ 3.975–3.899 eV) values. The frequency dependence of dielectric properties was described as a function of composition. The results expressed that the high dielectric constant (e′) of 260.8 was noticed at 10 kHz for x = 0.8 composite. The dc-electrical conductivity (σdc) and exponent (n) parameters were determined by applying power law fit to the log σac versus log ω plots. The temperature dependence of dielectric constant plots indicated the dielectric transition temperature from 723 to 623 K with the increase of ‘x’.

In this work, the Ba0.2Sr0.8−yLayFe12O19 (y = 0.2, 0.4, 0.6 & 0.8) (BSLFO) nanorods were prepared using hydrothermal method. The hexagonal structure and nanorod formation were evidenced by X-ray diffraction patterns and micrographs, respectively. Further, the optical and magnetic properties of the BSLFO nanorods were investigated. Using the UV–Visible spectra of y = 0.2–0.8 contents, the optical bandgap (Eg) was determined. The Eg was increased from 3.502 to 3.714 eV as a function of La content. The Raman modes were detected using the Raman spectra for confirming the hexagonal structure of x = 0.2–0.8. The magnetic hysteresis curve indicated the decreasing trend of saturation magnetization (Ms) from 14.44 ± 0.507 to 4.15 ± 0.162 emu/g with ‘y’. This was determined using the law of approach to saturation (LAS) method. In addition, the magnetic permeability versus temperature (μ′-T) plots showed the decreasing nature of magnetic Curie transition temperature (Tc) from 753 to 703 K with increase of La content. Furthermore, the frequency dependence of magnetic permeability (μ′), magnetic loss (μ″) and relative magnetic loss (rlf: tanδ/μ′) was studied for all samples.

The Ba0.2Sr0.8-yLayFe12O19 (y = 0.2, 0.4, 0.6 & 0.8) (BSLFO) nanorods were prepared via low temperature, and inexpensive hydrothermal method. The presence of hexagonal phases was confirmed using the X-ray diffraction (XRD) patterns. The surface morphology revealed the formation of rectangular nanorods for y = 0.2–0.8 contents. Especially, y = 0.8 content showed the complete formation of rectangular nanorods due to high La-content. Furthermore, the dielectric properties, ac-electrical properties, impedance and dielectric modulus parameters were described as a function of composition, frequency and temperature.

Starch based Carbon nanotubes-iron oxide (CNT-IO) and Carbon Nanotubes-Zirconium oxide (CNT-ZO) Nanocomposites (NCs) were fabricated by using facile microwave irradiation technique from different plant-based starch sources namely Tapioca sago (TS), Hordeum vulgare (HV) and Eleusina coracona (EC) and metal oxide precursor solutions. These NCs were studied using different characterization techniques such as SEM, TEM, XRD, Raman spectroscopy and FTIR spectroscopy. The Structural morphology of Starch based CNT-IO and CNT-ZO NCs observed like a rolled tubular structures and exhibiting strong blue luminescence with the charge transfer between CNT and Metal oxide. We have evaluated the anti-proliferative and anti-oxidant activity of starch-based CNT-IO and CNT-ZO NCs using MCF-7 cell line compared with the standard drug camptothecin and DPPH assay. Among the various NCs studied antiproliferative activity, CNT-IO and CNT-ZO obtained from starch source Eleusina coracona was effective with IC 50 values of 12.3 and 18.2 µg/mL respectively. Moreover, the enhanced radical scavenging activity has also been observed for these NCs.

This work is mainly devoted to study the magnetic properties and dielectric properties BaNixZnxFe12−2xO19 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5)/ BNZFO. These samples were synthesized by the hydrothermal method followed by calcination at 950 °C. The X-ray diffraction patterns revealed that BNZFO samples were crystallized into a hexagonal structure with the space group P63/mmc. The lattice parameters increase with the increase of Ni2+ and Zn2+ ions substitution in BNZFO. The crystallite size significantly increased from 1.3 µm to 29 µm with the increase of Ni2+ and Zn2+ ions composition. FESEM studies revealed that hexagonal plates like morphology with small fraction of rods like grains (except for x = 0.0) with an average grain size from 1.72 to 4.96 µm. The FTIR spectra showed two prominent peaks at 583 and 430 cm−1 indicated the formation of Fe–O bonds in all samples. The room temperature M-H curves showed that the coercive field was decreased from 3091 to 671.92 Oe while the increase in saturation magnetization was noticed from 48.22 to 63.37 emu/g as a function of ‘x’ from 0.1 to 0.4. The narrow optical band gap values of BNZFO were altered between 1.36 to 1.88 eV and discovered the semiconducting nature of samples. The increasing trend of dielectric constant and dielectric loss values was observed with an increase in x = 0.0 to 0.5. The Maxwell–Wagner’s interfacial polarization effect was observed in all samples (x = 0.0–0.5). The complex modulus and impedance spectroscopy analysis indicated non-Debye type relaxations and the electrical conduction mechanism due to both grain and grain boundary contributions among all samples. In view of all these properties, BNZFO samples are potential candidates for opto-electronic, magneto-optic, magnetic-recording devices, photocatalytic and sensor-based applications.

The present work focussed on the preparation and characterization of AlxLa1−xTiO3 (x = 0.2–0.8) (ALTO) nanospheres. The phase purity and tetragonal structure was confirmed using the X-ray diffraction patterns. In addition, the dimensions of the ALTO unit cell were decreased with increase of Al-content. The morphological investigations evidenced the formation of spherical grains and particles of nano size. The UV–Visible spectra revealed the increasing trend of band gap (Eg) from 3.341 to 3.378 eV as a function ‘x’. Besides, the frequency, and compositional variation of dielectric parameters was described. Subsequently, the space charge polarization, and electrical conduction mechanisms were well understood using the complex dielectric modulus, and impedance spectroscopy. The Cole–Cole plots ensured that the ALTO materials exhibited the semiconducting nature due to the formation of complete semicircular arcs. Moreover, the non-Debye type relaxations were noticed in Cole–Cole plots.

Microwave sintered magnesium ferrite (MF) nanoparticles are synthesised by hydrothermal technique. X-ray diffraction revealed pure spinel phase but low crystallinity. Synthesised MF is observed to be in nanoscale under scanning electron and transmission electron microscopes. MF is characterised further by Fourier transform infrared and UV-visible spectrometers for vibrational bands and optical band gap information. Electric and magnetic characterizations revealed low conductivity, dielectric loss, magnetic loss and fairly good initial permeability. High coercivity and M-H loop area of MF indicate the hard magnetic nature.

The hexagonal Ba1-xSrxFe12O19 (x = 0.0, 0.2, 0.4, 0.6 & 0.8) (BSFO) nanoparticles were synthesized by hydrothermal method at low operating temperature of 150 °C/8 h. Latter, the diffraction peaks confirmed the hexagonal structure. The spheres (x = 0.0, 0.2 & 0.6), flat plates (x = 0.4) and rectangular fibers (x = 0.8) like grains were noticed in the microstructure. The transmission electron microscope (TEM) studies revealed the particle diameter (Dp) changing from ~7–29 nm for all samples. Furthermore, the narrow optical band gap energies (Eg) were noted to be ~ 2 eV which may be suitable for optoelectronic and photocatalytic applications. Moreover, the temperature dependent ferroelectric behavior of BSFO was examined using polarization versus applied electric field (P-E) loops. The space charge polarization was observed at low frequencies of dielectric constant (e'), dielectric loss (e"), ac-conductivity (σac), dielectric modulus (M' & M"), and impedance (Z' & Z") plots of BSFO. The Arrhenius plots (lnσ versus 103/T) were dawn to find the activation energies (Ea & Eb). Moreover, the Cole-Cole plots were also drawn as a function of temperature from 313 to 473 K in order to investigate the conduction mechanism through grain/grain boundaries.