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The proficient realization of Na-ion batteries (NIBs) having exceptional electrochemical behavior is considered to bridge the hurdles triggered by inadequate resources and costly manufacturing of Li-ion batteries. Herein, we report a facile synthesis of Ni0.06Co2.94O4/CNTs hybrid using the solvothermal route and Ni0.06Co2.94O4 using the hydrothermal approach. The formation of a nest-like conductive framework of Ni0.06Co2.94O4/CNT composites, aligning favorably to form an assembly of a layered structure, supports an efficient Na-ion insertion/extraction process. A high initial charge capacity of 621 and 582 mAh g-1 is delivered by Ni0.06Co2.94O4/CNTs and Ni0.06Co2.94O4 electrodes, respectively which retained up to 328 and 239 mAh g-1 after 100 cycles. The electrodes also delivered excellent rate performance with 119 and 93 mAh g-1 at 5.0C and retained 77 and 64% of initial capacity, respectively when recovered from 0.05C. Additionally, Ni0.06Co2.94O4/CNTs exhibited low impedance over a wide range of frequencies resulting in more Na ions storage and a faster Na insertion/extraction process. The exceptional performance shown by the hybrid electrode is due to the synergistic influence flanked by binary metal oxides and CNTs. Hence, the hybrid of Ni-doped metal oxide and carbonaceous species emerge as an excellent choice for use as an electrode for electrochemical energy storage devices.

Triphase multiferroic composites with higher degree of freedom, provide a new platform for developing novel and smart technological applications. In this context, here we present a new triphase composite, consisting of bismuth ferrite (BFO) and lead zirconate titanate (PZT) synthesized using sol‒gel auto-combustion and solid-state routes, respectively and then subsequently dispersed into a PVDF polymatrix, leading to a triphase composite (BFO-PZT-PVDF). Structural analysis confirmed the composite formation as all the intensity peaks were either matched with BFO or PZT phases. Morphological analysis revealed that pure BFO and PZT formed well defined grains with sharp grain boundaries. However, when they are dispersed in the polymer matrix, their boundaries became diffused. Worth mentioning ferroelectric parameters like saturation polarization, remanent and recoverable energy density are measured from bipolar polarization loops. It is noticed that maximum polarization is decreased while coercivity is increased with the increment of PZT contents in the composite. Vibrating sample magnetometer confirmed the variation in magnetic features, exactly in accordance as required for significant magnetoelectric coupling for practical utilization. The extent of magnetoelectric coupling supports the potential applications of these triphase composites for energy storage and multistate devices.

Energy storage materials play a vital role in modern technology. A single device can perform multifunctions if fabricated using a multifunctional material like BiFeO3. For this purpose, a series of La and Cr doped BiFeO3 was synthesized using sol‒gel auto-combustion technique. A single phase rhombohedral distorted perovskite crystal structure related to bismuth ferrite with space group R3c (161) was confirmed from the X-ray diffraction patterns. Doping of La/Cr at Bi/Fe lattice sites in BiFeO3 did not affect the crystal symmetry of the parent compound. Morphological analysis exhibited homogeneous micro structures showing uniform distribution of multi-shaped grains with decreasing porosity and grain sizes with increasing Cr contents. These materials exhibited the conventional ferrite-like dielectric response, which gradually decreased with increasing frequency and lastly became constant in the high frequency regime. Impedance spectroscopy revealed the contribution of grains, grain boundaries and interfaces in electrical response of the samples. Frequency dependent electric modulus analysis confirmed the non-Debye type relaxation.

Here, we report CNTs-TiO2 nanocomposites synthesized using the hydrothermal technique to investigate their potential utilization in energy storage devices. Different weight percentages (0.3, 0.5, and 0.7 wt.%) of CNTs are added in TiO2 nanoparticles to tune their energy storage capacity. Structural analysis reveals the tetragonal crystal symmetry of TiO2 nanoparticles. Morphological investigations expose that the average particle size of TiO2 is 27 nm whereas the average diameter of CNTs is ~20 nm. Cyclic voltammetry confirms that the specific capacitance of CNTs-TiO2 nanocomposites increases from 149.5 to 367.1 mF/g with increasing concentration of CNTs. However, maximum power density is noticed for nanocomposites with 0.5 wt.% of CNTs. The value of specific capacitance and power density is noticed as 335 mF/g and 400.90 Wkg−1, respectively. In addition, dispersion in dielectric behavior, variation in impedance response, and the presence of relaxation phenomenon are elaborated in a vast frequency range.

Cost-effective synthesis, portability, quick response and fascinating features of semiconducting metal oxide sensors have drawn much accredited to be utilized in wide variety of potential sensing applications. Herein, flexible acetone sensor was fabricated through spray coating method using different conductive inks of carbon nanotubes (CNTs), zinc oxide (ZnO) and silver (Ag) nanoparticles solutions on cellulose paper. Morphological analysis revealed the fiber like morphology of cellulose over which CNTs, ZnO and Ag nanoparticles are uniformly distributed. The energy dispersive X-ray spectroscopic analysis was performed to observe the elemental composition in the as-prepared samples. The recovery time toward acetone was greater for CNTs/Ag acetone sensor at 95% as compared to CNTs/ZnO/Ag sensor. Additionally, sensing time of the samples towards acetone was measured and the observed response time was greater for CNTs/ZnO/Ag (0.52 s) acetone sensor as compared to CNTs/Ag sensor (0.41 s). Hence, CNTs/ZnO/Ag can be easily employed for sensing applications due to quick response.

Intense research work is underway for identifying materials with potential applications in energy storage and energy harvesting systems. The magnesium based scandium chalcogenides have recently emerged as potential candidates for Mg batteries owing to their high Mg ionic conductivity and low electron conduction. At the same time, their band gaps are capable of absorbing electromagnetic radiations in visible to UV range; making them suitable for solar cell applications. In order to analyze the application of MgSc2X4(X = S, Se) compounds in energy devices, in this work we employ density functional theory calculations using the full potential linear augmented plane-wave method for examining their optoelectronic and thermoelectric properties. For the structural properties, the generalized gradient approximation functional designed for solids (PBEsol-GGA) has been used, while modified Becke and Johnson (mBJ) potential functional is used for computing the optoelectronic and transport properties. Our calculated optical properties indicate that these materials can find applications in solar cells. Moreover, the electronic transport properties computed using Boltzmann transport equation suggest carrier concentrations in MgSc2S4 to MgSc2Se4 spinels can be tuned for making them suitable for metal ion batteries.

Using a time efficient and cost effective approach so called sol‒gel dip coating route, we deposited thin films of ZnO and 1% Co & (0%, 0.5%, 1%, and 1.5%) Ga co-doped ZnO on the fluorine doped tin oxide substrates. All the films exhibited hexagonal wurtzite structure. X-rays study revealed that crystallite size increased with increase of doping. Optical parameters like absorbance, transmittance, refractive index, band gap, extinction coefficient and dielectric constants were measured using UV–Vis spectroscopy and it has been noticed that doping resulted in reduction of band gap. It has also been observed that, the films prepared with 1% Co & 1% Ga co-doped ZnO have comparatively smaller band gap and thus have high refractive index and high transmittance in visible region. The calculation of different electrically important factors for instance, high current density, small open circuit voltage, efficiency and fill factor revealed that co-doped ZnO with 1% Co and 1% Ga has relatively high efficiency of 2.43% and thus shows the potential of this composition as an electrode for solar cell devices.

A comprehensive investigation of the physical characteristics of any material provides beneficial information regarding its application viewpoint in different industries. Herein, we report the tunable mechanical and optoelectronic properties of cubic CdZrO3 under variable pressure up to 80 GPa using density functional theory (DFT). The pressure-induced band gap engineering reveals a fantastic fact of transformation of the indirect to direct band gap with increasing pressure. The dielectric response disclosed that optical parameters dragged towards higher energy with an increase of pressure, which unveiled the potential of CdZrO3 for optoelectronic applications. Effective change in optoelectronic is attributed to indirect to direct band gap transition. This study provides a gateway to how the optoelectronic properties of cubic CdZrO3 could be tuned by employing external pressure.

Pure and palladium (Pd) doped Diamond-like carbon (DLC) thin films have been deposited on glass substrates by using KrF Excimer laser having 248 nm wavelength. The doping concentration of Pd in DLC is 0%, 0.5%, 1.0%, 1.5% and 2.0%. Internal structure, surface morphology, mechanical and electrical characteristics have been carried out by Raman spectroscopy, scanning electron microscopy (SEM), Vickers hardening and four point probes, respectively. Using Raman spectra an improved graphitic behavior of DLC has been observed with increase of Pd contents. Some nano rods were observed at the surface of pure and Pd doped DLC thin films. With increase of Pd concentration in DLC, initially there is an accumulation of particles is observed and when the doping concentration is high i.e. at 2%, cracks formation takes place. The electrical resistivity is decreased by adding Pd into DLC thin films. Further, doping of Pd decreased the hardness of films. These characteristics of Pd doped DLC with increased hardness and electrical conductivity make it potential candidate for electronic devices. Also, doping enhance the graphitic behavior, therefore this material can be used for anti-bacterial and anti- cancerous activities.

Dye Sensitized Solar Cell (DSSC) is a potential too to convert solar energy into electrical energy due to its low cost, ease in synthesis and higher photo electron conversion efficiency (PEC) in contrast with conventional silicon solar cell. The photo-electrode of DSSC is a key component which is responsible for collection and transportation of electrons through the circuit. Sol-gel route was adopted to manufacture photo anodes of 1% Zinc doped titanium dioxide (Zn–TiO2) where FTO glass was used as substrate. These photo anodes were irradiated by 300 keV Cobalt (Co) ions with different fluence rates as 2 × 104 atomscm-2s-1 and 4 × 104 atoms cm-2s-1. We investigated the anatase phase of TiO2 using the Raman spectra which also showed that Zn and Co are completely doped in TiO2. UV–visible spectroscopy showed that band gap of films was decreased by doping and ions implantation. Maximum reduction in band gap is observed at the fluence rate of 4 × 104 atoms cm-2s-1 i.e. 2.77 eV. SEM micrographs showed that the film irradiated with Co ions with fluence rate of 2 × 104 atoms cm-2s-1 have maximum porosity which supports the maximum dye loading on the surface due to which the efficiency of DSSC is enhanced. In all cells, N719 dye is used as sensitizer. The solar simulator results indicated the higher efficiency up to 3.78% is achieved by 300 keV cobalt ions irradiation with fluence rate of 2 × 104 atoms cm-2s-1. The present work shows that the appropriate percentage of Co ions in Zn–TiO2 layer plays a significant role to escalate the effectiveness of DSSC.

Precise control of morphology of functional materials, in particular when grown on nanoscale has revolutionized their physio-chemical characteristics for various applications. These nano-dimensional materials serve as basic building blocks for the development of new technological applications. Here in, we synthesized a series of nanorods and nano flakes of Co/Ni spinel ferrites using a hydrothermal method. NH4F as a surfactant, assisted to precisely control the morphology and dimension of nanostructures. The transformation of inverse spinel structure of cobalt ferrite to mixed spinel upon Ni substitution remarkably influenced their dielectric and ferroelectric response. The increase of dielectric response with Ni substitution was explained on the basis of Maxwell Wagner model. The impedance investigation probed the activation of different electro-active regions in different frequency range. Ferroelectric behavior along with energy density calculation provided a map to estimate the potential of functional nanostructures for energy storage applications. Magnetic properties were also obtained at room temperature showing high coercive hysteresis loops.

In this modern age of technology, flexible, light-weight, environment-friendly and low-cost electrodes are vastly feasible for applications in energy storage devices and disposable electronics. This study presents a comprehensive report on the morphological, dielectric, and impedance characteristics of lignocellulose (LC) fibers, PbO2, and LC/PbO2 sheets. The dielectric analysis shows that the dielectric constant depends on space charge polarization in the case of LC/PbO2 composite sheets. It can be concluded from impedance spectroscopy results that LC fibers show semiconductor-like behavior and fibers appear to consist of one type of dielectric species whose impedance behavior can be modeled by a parallel combination of a resistor and a capacitor. However, the impedance response of PbO2 consists of two types of dielectric species, which can be identified as grains and grain boundaries, both of which show a small temperature dependence. The impedance behavior of LC/PbO2 composite is different in comparison to individual LC fibers and PbO2. The presented study also reveals that impedance parameters of fabricated LC/PbO2 composites are temperature-independent, which might be due to counteracting the characteristics of LC fibers and PbO2 particles. This temperature-independence of the composite is important for their use in applications in flexible devices.

Increasing demand of multifunctional devices has attracted researchers and scientists toward materials having magnetoelectric coupling as they can provide an extra degree of freedom to device fabrication. In this regard, composites of antiferromagnetic perovskites and ferromagnetic spinels comprise a prospective recipe. Here, we report (1-x)BiFe0.9Mn0.1O3-xNiFe2O4 (x = 0.00, 0.10, 0.20, 0.30, 0.40, and 0.50) nanocomposites prepared by a two-step route. Analysis of the data obtained from diffractometer confirmed the corresponding crystalline phases of Mn-doped BiFeO3 and NiFe2O4. Formation of nanoparticles was confirmed by field emission scanning electron microscope. Presence of stoichiometric amounts of all elements in composites was confirmed by energy dispersive X-ray spectroscopy. To understand the dielectric relaxation phenomenon, we examined dielectric spectra in a wide frequency range, something that helped us probe the nature of charge transition inside the samples. Increasing NiFe2O4 contents in composites improved the ferroelectric and magnetic response of the material with noticeable magneto-electric coupling, showing the potential of these composites for multifunctional device fabrication.

The presence of multiferroic behaviour in any material makes it exceptionally important for its possible significant role in technological developments. The combination of dielectric and magnetic orders in a single device has become an intriguing topic for material scientists in recent days. In this context, sol‒gel auto-combustion technique was utilized to synthesize Zn-substituted NiCo2O4 to exploit its energy and data storage pursuits. Spinel-based cubic structure of metal cobaltites was affirmed using X-ray diffraction technique. Enhancement in grain size mediated by Zn substitution was visualized. Furthermore, elemental analysis confirmed the required stoichiometric contents in the samples. Koop’s theory, consistent with Maxwell–Wagner model, elaborated the decrease in dielectric constant by enhancing the frequency. An energy loss in dielectric relaxation was probed by measuring the loss tangent. In addition, the substitution of Zn also caused a decrease in resistive behaviour of the samples. Magnetic analysis revealed that when Ni was replaced with Zn, the saturation magnetization decreased which was attributed to the relative magnetic dipole moments of Zn and Ni.

In this letter, we report the energy storage capacity and magneto-dielectric tenability of rare earth zirconates, by synthesizing a series of Ce-substituted neodymium zirconates having general formula, Nd2Zr2−xCexO7 (x = 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0), using sol–gel auto-combustion method. Linear ferroelectric response and energy storage efficiency was checked from polarization loops. Magnetic characterization revealed that rare earth zirconates had small values of coercivity and remanence which argued mainly a superparamagnetic nature of the samples. Tailoring of dielectric properties with the magnetic field and a possible origin of magneto-dielectric coupling was also investigated.

To meet the demand of modern flexible and disposable technology, directly collected lignocelluloses fibers and graphite composite are successfully fabricated with uniformly electrodeposited of thin layers of nickel, silver and nickel. These multilayers (Ni-Ag-Ni) were electrodeposited on lignocelluloses-graphite sheet by using three electrode setup at a constant reduction potential (−0.95 V) between the electrodes. Composition and nanostructures of these nanocomposites (LC-graphite-multilayers) were investigated by using energy dispersive x-ray spectrometry, field emission scanning electron microscopy, Raman spectroscopy, UV–VIS and impedance spectrometer. FE-SEM images revealed that Ni-Ag-Ni layers are uniformly integrated into LC-graphene matrix and EDX analysis confirmed the deposition of multilayers Ni and Ag. Dielectric analysis revealed the non-linear frequency dependent response of the multilayered deposited LC fibers based nanocomposite. Complex impedance spectroscopy analysis presented the multilayered deposited LC fibers based paper electrode for high-tech applications in optical and electronic devices.

The key phenomena in multiferroic materials are their spontaneous polarization and magnetization. In order to meet the modern needs in the field of information technology and engineering, their coupling has been of great interest for generating marvel applications. Based on this idea, sol–gel auto-combustion method was utilized to synthesize BiFeO3 and MnFe2O4 which were moulded together in a composite by ball milling. For all the calcined samples of (1 − x)Bi0.9La0.1Fe0.9Mn0.1O3-(x)MnFe2O4 with different concentrations of MnFe2O4 i.e. at x = 0.00, 0.30, 0.50, 0.70 and 1.00, XRD was utilized for the analysis of crystal structure. It depicted the rhombohedral structure of BiFeO3 without any phase shifting throughout the samples, except at x = 1.00, for pure MnFe2O4, exhibiting cubic structure with no peak of BiFeO3 involved. Surface morphology was analysed using FESEM which confirmed that the granular size increased with the increase in MnFe2O4 concentration. For finding the weight percentage and elemental composition of the prepared composites, EDX analysis was carried out which revealed the presence of Bi, Mn, Fe, O, La in accordance with their stoichiometric formula. Vibrating sample magnetometry was put into use to inspect the magnetic properties of the synthesized composites and it was found that with the enhancement of MnFe2O4, magnetic characteristics were significantly improved. At last, precision multiferroic tester was used to examine the ferroelectric properties at 10 V. The PE loops, recoverable energy density, energy loss density and energy efficiency revealed a nice ferroelectric response in BiFeO3 dominating compositions. These interesting features uncovered the potential of these compositions for energy storage devices.

Pyrochlore structure based compounds have shown valuable interest in practical applications because of their structure tunability and stability. In this context, the stability of pyrochlore structure in a particular phase is quite essential for practical optimization of valuable dielectric and impedance characteristics of rare-earth zirconates. Thus, in the present work, a series of Nd substituted lanthanum zirconates were synthesized to investigate its effect on the structural, morphological, electrical and dielectric properties. Structural analysis confirmed the formation of sustainable pyrochlore phase in all the samples having space group Fd 3 m . A drastic reduction in grain size with Nd substitution was visualized by the images obtained using a field-emission scanning electron microscope. The electrical impedance spectroscopy was performed to check the frequency response of the dielectric behaviour, giving tenable information about changes in electrical permittivity due to Nd substitution. Impedance analysis shows a contribution of grains and grain boundaries in these heterogeneous zirconate samples. These regions are easily distinguishable in the sense of their electrical conductivity and impedance characteristics. The conductivity values obtained were lying in the range of nano-Farad predicted these materials to be used as solid oxide fuel cells.

The synthesis of pure ZnO along with nominal Mn and Co co-doping using a time-efficient and cost-effective wet chemical route to explore their detailed dielectric response is reported. Structural investigations revealed the development of hexagonal crystal symmetry of pristine ZnO. When 5% Mn is substituted, a slight decrease in lattice parameters is observed. However, Co doping did not affect the crystal symmetry as well as lattice parameters. The morphological study exposed that Mn and Co incorporation in ZnO significantly affected the shape, size, and distribution of particles. The maximum porosity is noticed when 5% of Mn is doped in pure ZnO. The elemental analysis confirmed the presence of all elements according to their stoichiometric formula. The relatively higher value of the dielectric constant is noticed in the present case while the value of loss tangent is explained based on oxygen vacancies generated during the auto-combustion process. Short-range electron transport is distinguished from long-range on the basis of relaxation peaks present in electric modulus. The effective contribution of conducting grains and insulating grain boundaries in different frequency regimes is explained by their impedance response.

Advantageous utilization of sodium-ion batteries (SIBs) requires superior performance, enriched with cost-effective anode materials, having excellent storage capability, high conductivity, and structural stability. Hybrid structures based on inorganic metal oxides and organic nano-carbons are evolving as satisfactory electrode materials for the next-generation SIBs owing to their exceptional properties. In this study, Co2.98Zn0.02O4/CNTs hybrid is synthesized using a facile hydrothermal followed by a solvothermal route. As prepared hybrid has been utilized as an anode in a Na half cell and the results are compared with Co2.98Zn0.02O4 and bare Co3O4 anodes. Galvanostatic charge-discharge profiles revealed a high reversible capacity of 721 mAh g−1 for the electrode containing carbon nanotubes (CNTs) i.e. Co2.98Zn0.02O4/CNTs exhibiting remarkable coulombic efficiency of 99% as compared to the other two electrodes. The hybrid anode showed improved capacity retention (289 mAh g−1) after 100 cycles as computed from the cyclic test which is much higher than bare Co3O4. The rate capability test of Co2.98Zn0.02O4/CNTs showed that specific capacity retained as high as 138 mAh g−1@10 C which is an outstanding rate performance, whereas bare Co3O4 couldn’t perform even after 0.5 C. Sodium insertion/extraction is also improved for Co2.98Zn0.02O4/CNTs, as revealed by electrochemical impedance and diffusion coefficient. From these findings, it is inferred that carbon-based Zn-doped Co3O4 hybrid electrode materials can be a superior combination for high-performance and fast charging future SIBs.

To probe the applications in spintronics and sustainable energy devices of ZnMn2X4 (X=S, Se, Te) spinels, their structural, elastic, electronic and thermoelectric properties have been studied in the present work. Structural properties reveal stability of ferromagnetic (FM) phase in these spinels which is further confirmed by computing the heat of formation for these compounds. The mechanical properties of the ZnMn2X4 spinels have been investigated by computing their elastic constants, which show that all these spinels exhibit a brittle character. Moreover, electronic band structure and density of states reveal a half-metallic FM structure in all these spinels. Analysis of the band structure of these materials reveals a semiconducting nature in the spin down channel. Exchange constants (N0α and N0β) have been computed to directly probe the state splitting and our results large splitting of Mn 3d-states by N0β owing to its larger negative value as compared to N0α. The strong p-d hybridization is found to make exchange field dominant to crystal field which consequently induces ferromagnetism. In addition, the p-d hybridization reduces the magnetic moment of Mn ions by inducing traces of magnetic moments at non-magnetic sites. The observation of thermoelectric behavior within temperature range 200K–800K reveals positive Seeback coefficient indicating holes as majority charge carriers. Although the power factor is found to increase on going from ZnMn2S4 to ZnMn2Te4, our results clearly show improvement of power factor with increasing temperature.

Nanoscale designing of polymer based architectures is essential to enhance the efficiency of energy storage devices for their potential applications in modern day technology. Usually, two phase nanocomposites develop a single type of interface between matrix and filler, causing an increase in dielectric constant and high energy density at the cast of charge discharge efficiency. Herein, we report a three phase (GO/CoFe2O4/PPy) novel class of nanocomposites capable of exhibiting high energy density storage. Three different components of this nanocomposite were synthesized using Hummer’s method, sol-gel auto-combustion technique and polymerization route, separately which were then combined using solution mixing technique in the presence of 0.3 M solution of FeCl3·6H2O. The development of inverse spinel structure of CoFe2O4 and its phase stability was analyzed using X-ray diffraction. Evolution of a variety of nanoarchitectures was confirmed by a field emission scanning electron microscope and its consequences on dielectric and ferroelectric response were probed via precision impedance analyzer and precision multiferroic tester. For the identification of functional groups, Fourier transform infrared spectroscopy was employed and conductive nature was examined using their I–V response curves. Dielectric response of PPy mediated by GO and CFO contents was explained on the basis of Maxwell-Wagner model. The magnetic hysteresis loops were employed and maximum magnetization, remnant magnetization, coercivity and squareness ratio were measured. Using polarization-electric field loops, energy density measurements were carried out which revealed the potential of these nanocomposites for energy storage devices.

Pure and Ni/Co co-doped BiFeO3 samples were prepared through sol‒gel auto-combustion technique. The synthesized samples were calcined at 500 °C for 1 h before further characterizations. The rhombohedrally distorted cubic perovskite structure was confirmed for all samples through X-ray diffraction analysis. The surface morphology of each sample was visualized using scanning electron microscopy which elaborated the formation of spherical grains along with some agglomerations. Energy dispersive X-ray spectra revealed the presence of Bi, Fe, O, Ni and Co atoms in the same atomic and weight percentages as expected from their empirical formulae. The frequency dependent dielectric constant, tangent loss and impedance characteristics were investigated using impedance analyzer. It was also noticed that the ac conductivity increased when Ni and Co were substituted at equal amounts. The magneto-electric analysis witnessed the coupling between different ferroic orders in these samples.

Intense research has been done to build materials that are potential candidates for energy storage applications. Spinels are of great interest in this respect because they have vast potential to be used in Mg-based batteries. To explore their energy storage as well as transport response, we calculate Mg-based spinels, namely MgLu2Z4 (Z S, Se). The full potential linearized augmented plane wave method has been used to examine their optoelectronic and transport response. An increase in the lattice constant has been observed by replacing S with Se, and our calculated values are in good agreement with those obtained experimentally. The Tran-Blaha modified Becke-Johnson exchange potential (TB-mBJ), has been used to study the optoelectronic and thermoelectric characteristics of the respective spinels. The dependence of these properties on the bandgap has also been observed. Replacing S with Se resulted in the transformation of the electronic bandgap from near-infrared to the visible region (MgLu2S4: 2.60 eV and MgLu2Se4: 2.00 eV). These results showed that these materials have the potential to be used in optoelectronic devices. The optical properties are discussed as a function of energy. Besides, the thermal transports are discussed with the help of Seebeck coefficient and figure of merit as a function of chemical potential and temperature.

BiFeO3-based multiferroic ceramics if prepared in phase pure form possess wide range of applications based on their charming and switchable polarization, piezoelectric, magnetoelectric and spintronic properties. In this regard, we investigate the influence of Mn substitution at Fe-site in BiFe0.99Cu0.01O3 samples, synthesized by sol–gel-based self-assisted combustion technique. Crystal structure was determined using X-ray diffraction which revealed a rhombohedrally distorted cubic perovskite structure of all the samples. The lattice constant increased, while crystallite size decreased with increased concentration of Mn. A systematic analysis of frequency-dependent dielectric constant, loss factor, tangent loss and impedance has been presented using an impedance analyzer. It is observed that the trend of dielectric constant, loss factor, tangent loss and impedance is decreasing with increasing frequency. It was also observed that electrical properties were mainly influenced by dominance of grain boundaries effect in 20 Hz–20 MHz range. Effect of increased concentration of Mn on frequency-dependent dielectric properties has also been discussed, and it is found that dielectric properties decreased with increasing concentration of Mn mainly attributed to the suppression of oxygen vacancies.

Multiferroic nanoparticles having general formula BiFe0.99-xMnxCu0.01O3 (x = 0, 0.01, 0.02, 0.03 & 0.04) were prepared by a chemically derived method to explore the magneto-electric characteristics of this new class of materials. X-ray diffraction confirmed that all the samples had rhombohedraly distorted cubic perovskite 3D lattice. Lattice constant was increased with increasing concentration of Mn. Micrographs obtained from a field emission scanning electron microscope revealed a fine distribution of well-shaped particles while the particle size was increased with increased contents of Mn. Enhanced hopping mechanism induced by substitution of Mn at the lattice sites of Fe resulted in an increased AC conductivity. Ferroelectricity was observed to increase with increased Mn, attributed mainly to the leakage current due to free charge carriers instigated by multiple oxidation states of Fe and Mn. It has been observed that antiferromagnetic bismuth ferrite begins to show ferromagnetic behavior due to the collapse of antiferromagnetic spin structure with increased Mn contents.

Graphene oxide (GO) and polymer based nanocomposites are emerging as a new class of materials having potential for flexible electronic devices and modern day energy storage devices. The traits like high mechanical strength, non-corrosive nature, low weight, being cost-effective, flexible, thermal and electrically insulated have made polymer based nano architectures highly effective for utilizing in energy storage applications. In the present research, the variation in structure, morphology and dielectric response of polypyrrole (PPy) is investigated by adding the nickel ferrite (NiFe2O4) and GO in it. The nano-materials, PPy, NiFe2O4 and GO were prepared by pyrrole’s polymerization, sol‒gel auto-combustion method and modified Hummer’s method, respectively. The solution mixing method was carried out to form GO/NiFe2O4/PPy nanocomposites with different concentrations by slowly mixing the already equipped nanomaterials. X-ray diffraction technique was employed for phase identification of as-prepared nanocomposites. The surface study and elemental composition was examined via field emission scanning electron microscope and energy dispersive X-ray spectroscope, respectively. The dielectric response of these samples was probed using impedance analyzer that was found to be in good agreement with Maxwell-Wagner model and Koop’s Phenomenological theory. Effective contribution of different electro-active regions was investigated from Nyquist plots.

Pyrochlore materials show intensive potential for various everyday applications owing to their highly stable structure with tunable lattice parameters. Energy storage tunability and switching capabilities of these materials can further be improved using suitable cationic substitutions. In this context, we report a series of Nd-substituted lanthanum stannate (La2−xNdxSn2O7) pyrochlores, prepared using sol-gel auto-combustion method. It has been observed that Nd-substitution finely tuned the lattice parameters of parent compound without compromising its cubic phase stability. The gradual replacement of La with Nd resulted in well crystalline grains, adopting diamond and cubic like shapes. Ferroelectric nature, electrical conductivity, switching charge density and normalized capacitance, which are among the key features of a ferroelectric material, were also analyzed. The increasing difference between saturation and remanent polarizations, especially when x ≥ 1.2, make them a potential candidate for energy storage devices. The maximum value of energy density efficiency i.e. more than 60% was observed for pure Nd2Sn2O7. In addition, low switching charge density makes them prominent for fast switching applications. Magnetic response revealed their superparamagnetic behavior with small remanence and low coercivity (~30 Oe), which exposed their potential for biomedical applications provided its particle size is controlled.

Controlled growth of nanostructures plays a vital role in tuning the physical and chemical properties of functional materials for advanced energy and memory storage devices. Herein, we synthesized hierarchical micro-sized flowers, built by the self-assembly of highly crystalline, two-dimensional nanoplates of Co- and Ni-doped BiFeO 3 , using a simple ethylene glycol-mediated solvothermal method. Pure BiFeO 3 attained scattered one-dimensional nanorods-type morphology having diameter nearly 60 nm. Co-doping of Co and Ni at Fe-site in BiFeO 3 does not destabilize the morphology; rather it generates three-dimensional floral patterns of self-assembled nanoplates. Unsaturated polarization loops obtained for BiFeO 3 confirmed the leakage behaviour of these rhombohedrally distorted cubic perovskites. These loops were then used to determine the energy density of the BiFeO 3 perovskites. Enhanced ferromagnetic behaviour with high coercivity and remanence was observed for these nanoplates. A detailed discussion about the origin of ferromagnetic behaviour based on Goodenough–Kanamori's rule is also a part of this paper. Impedance spectroscopy revealed a true Warburg capacitive behaviour of the synthesized nanoplates. High magneto-electric (ME) coefficient of 27 mV cm −1 Oe −1 at a bias field of −0.2 Oe was observed which confirmed the existence of ME coupling in these nanoplates.

The zinc zirconate ZnZrO3 perovskite have been studied with respect to their physical properties by inducing pressure upto20 GPa. The predicted value of lattice constant for ZnZrO3 determined using PBEsol-GGA is reasonable agreement with experimental value. Our calculations showed that Born mechanical stability criteria, confirmed the mechanical stability in cubic phase. Further, through Poisson and Pugh’s ratios critical limits, the findings of the ductile strength have been computed. To explore the pressure induced band structure modification, a varying external pressure from 0 GPa to 20 GPa has been applied with a step size of 5 GPa. The change in band structure significantly affected the optical properties of the material under study. It was observed that the band gap of ZnZrO3 shifted from indirect to direct at applied pressure of 15 GPa. The effect of this shifting on the dielectric constant, optical loss factor, reflection, refraction and absorption has been carried out in this work. To probe the potential of this composition for thermoelectric applications, its electrical conductivity, thermal conductivity, See-beck coefficient and power factor were also calculated.

The physico-chemical properties of polymer ceramic composites highly depend upon the nature of ceramic, polymer and their interface. Among other interesting features, they have potential for flexible electronics and energy storage devices. Especially, graphene based polymer ceramic composites are unique for their high dielectric characteristics. In this regard, we synthesized a three constituent novel nanocomposite with polymer matrix to check their potential for energy storage applications. Here in, the polypyrrole has been exquisitely decorated with graphene oxide and manganese ferrite nanoparticles with their different concentrations. The development of spherical grains and their transformation into rod like morphology with a significant change in their dimension is noticed. The weight percentage of all elements according to their stoichiometric formula and the finger prints of different constituents in the form of their functional groups are also identified before their dielectric and ferroelectric analyses. The highest value of dielectric constant (121449) has been noticed at 100 Hz frequency, which reduced to 1066 at 1 MHz. The dielectric loss was also quite high at lower frequency which decreased to 1.2 at same high value of frequency (1 MHz). The calculations for recoverable energy density and energy loss density are performed using PE hysteresis loops and the highest value of recoverable energy density is recorded as 4.7 × 10−8 mJ/cm3. Thus, high values of dielectric constant and low dielectric loss of these nanocomposites make them attractive dielectric material in electrical appliances for capacitive applications.

Interfacial coupling in heterostructures of spinel-perovskite nanocomposites, primarily controls the performance of the multiferroic samples, especially in such type of binary structure systems. The interfacial response in this class of composites is a key feature to enhance the magnetoelectric response of the materials. For this purpose, here we synthesized a series of 0.5BiFeO3−0.5Ni0.5Co0.5Fe2O4 by substituting Zn at Co-site in spinel phase, using a facile wet chemical technique. The structural analysis carried out using X-ray diffraction revealed the presence of both the phases. Spherical type agglomerated grains with sharp and distinct grain boundaries were exposed by field emission scanning electron microscopy. Elemental profile was mapped by energy dispersive X-ray spectroscopy to confirm the stoichiometric composition of these composites. Improvement in saturation magnetization and remanence with increasing substitution contents was analyzed via vibrating sample magnetometer. In addition, the ferroelectric investigations were carried out to calculate the recoverable energy and energy loss density. Magneto-polarizability investigations uncovered the potential of these composites for multi-state device applications.

Graphene-based nanocomposite materials have drawn the serious attention of researchers due to their remarkable applications in the field of energy storage. Here, in the current work, the authors prepared various composite electrode materials composed of iron oxide and reduced graphene oxide. A simple cost-effective and one-step hydrothermal approach was employed, for the first time, using a combination of two reducing agents, namely urea and starch. The formation of composite materials was characterised using scanning electron microscopy and X-ray diffraction. The electrochemical characteristics of the as-manufactured composite materials were explored using cyclic voltammetry and galvanostatic charge/discharge tests. It was found that the iron oxide–reduced graphene oxide composite prepared by using two reducing agents exhibits higher specific capacitance (286.6 F g− 1) at scan rate of 5 mV s− 1 in 1M KOH solution.

Mg and La co-doped ZnNi spinel ferrites were synthesized to investigate the structural, optical and electrical properties using XRD, EDS, FESEM, FTIR, UV–vis and I-V characterization techniques. Formation of spinel cubic structure of ferrite nanoparticles was confirmed by XRD analysis. Energy dispersive x-ray spectroscopy ratified the presence of expected elements in each composition. Surface morphology exhibits the formation of nanoparticles in all compositions. FTIR spectra obtained for further supportive information about phase identification and metal oxide group. Optical properties were investigated using UV–vis spectrophotometry reveals decrease in band gap with addition of Mg2+ content which also in accordance with electrical resistivity measurements. It is inferred that ZnNi ferrites with La and Mg content can be used for low resistive ferrite applications.

In the present paper, we have investigated SmAlO3 for their thermodynamic properties under effect of pressure and temperature by employing density functional theory (DFT) and quasi-harmonic Debye model. The various thermodynamic properties like Bulk Modulus, entropy, internal energy, Helmholtz free energy, Debye temperature, coefficient of thermal expansion, Grüneisen parameter and heat capacities of the ternary alloy are calculated. We found that Bulk Modulus, Debye temperature and Helmholtz free energy have decreasing trend with rise of temperature while their values have increasing behavior with rise of pressure. The internal energy of the system almost remains same with variation in pressure but temperature effectively increasing it. Our results are in good agreement with available data at low-temperature limit.