Increasing Ni Doping Research Articles

Role of active redox sites and charge transport resistance at reaction potentials in spinel ferrites for improved oxygen evolution reaction

Fe and Ni oxide-based systems are often investigated as electrocatalysts for the oxygen evolution reaction (OER) in water electrolysis and the improvement in OER activity is explained by two main reasons, (i) improving bulk electrical conductivity and (ii) synergic effect between Ni and Fe. Among the two factors, the identification of the dominant factor for OER is very important for catalyst engineering in the right direction. In order to have a better understanding, spinel-structured ZnFe2O4 nanoparticles have been synthesized and its bulk conductivity is studied by progressively varying Ni doping. The conductivity of the synthesised compounds follows the order of ZnFe2O4 > Ni0.3Zn0.7Fe2O4 > Ni0.5Zn0.5Fe2O4 > Ni0.7Zn0.3Fe2O4 > NiFe2O4. The oxygen evolution studies reveal that NiFe2O4 is highly active with an onset potential of 1.57 V versus reversible hydrogen electrode (RHE) and Tafel slope of 102 mV/dec. With the increase in Ni doping, the structure changes from spinel to inverse spinel as confirmed by X-ray diffraction and Raman spectra. Further, the contribution from Ni redox sites in addition to Fe ion sites and FexNi1−xOOH species formation, causes improved OER performance. This study uniquely proves that the OER activity majorly relies on redox/active metal sites, FexNi1−xOOH species and charge transfer resistance at OER potential rather than the bulk electrical conductivity of spinel ferrites. This conclusion is supported by voltammetry and impedance studies of five different spinel ferrites.

Influence of Ni Doping on Oxygen Vacancy-Induced Changes in Structural and Chemical Properties of CeO2 Nanorods

In recent years, cerium dioxide (CeO2) has attracted considerable attention owing to its remarkable performance in various applications, including photocatalysis, fuel cells, and catalysis. This study explores the effect of nickel (Ni) doping on the structural, thermal, and chemical properties of CeO2 nanorods, particularly focusing on oxygen vacancy-related phenomena. Utilizing X-ray powder diffraction (XRD), alterations in crystal structure and peak shifts were observed, indicating successful Ni doping and the formation of Ni2O3 at higher doping levels, likely due to non-equilibrium reactions. Thermal gravimetric analysis (TGA) revealed changes in oxygen release mechanisms, with increasing Ni doping resulting in the release of lattice oxygen at lower temperatures. Raman spectroscopy corroborated these findings by identifying characteristic peaks associated with oxygen vacancies, facilitating the assessment of Ni doping levels. Ni-doped CeO2 can catalyze the ultrasonic degradation of methylene blue, which has good application prospects for catalytic ultrasonic degradation of organic pollutants. Overall, this study underscores the substantial impact of Ni doping on CeO2 nanorods, shedding light on tailored catalytic applications through the modulation of oxygen vacancies while preserving the nanorod morphology.

Tailoring the Magnetic, Structural and Shielding Characteristics of Nano Er2O3 via Ni Doping

We investigated the effects of Ni-doping amount on the structural, magnetic, and shielding properties of nano Er2O3. Nano Er2−xNixO3 (x = 0, 0.05, 0.1, 0.15) samples were fabricated by a pechini scheme and characterized via X-ray diffraction. Rietveld refinement was used to discover the distribution of cations on the two crystallographic sites. Cation ordering in the two nonequivalent sites of the structure and the variation of the oxygen bond lengths of octahedra with the composition x were also investigated. A consistent reduction in the average bond lengths of (Er/Ni)O6 octahedra around 8b and 24d as x progresses was observed. Average crystallite size reduced while average lattice micro-strain increased with increasing Ni doping. The correlation between magnetization and temperature for all samples under a magnetic field of 200 Oe was studied. Curie-Weiss law was applied to find the magnetic moments and the types of magnetic structure. The μ eff in the Er2−xNixO3 samples dropped from 9.7 to 9.36 μB as the nickel doping level rose from 0 to 0.15. Calculated magnetic moments, μ cal, were found to drop from 9.4 to 9.02 μB as the nickel doping level changed from x = 0 to x = 0.15 in Er2−xNixO3 samples. Curie paramagnetic temperature (θ) for all samples has been observed to rise from −10.6 to −19.34. The theoretical gamma-ray attenuation parameters for nano Er2−xNixO3 samples were acquired through the Phy-X/PSD software. The nano Er2−xNixO3 samples have been proven to possess remarkable magnetic and neutron shielding applications.

Boosting CO2 electrolysis via synergy between active heterogeneous interface and oxygen defects

The commercial viability of solid oxide electrolysis cells (SOECs) for the electrochemical reduction of CO2 to CO is hampered by the sluggish electrocatalytic activity of the electrode materials. In this study, a series of perovskites, Pr0.5Sr0.5Cr0.1Fe0.9-xNixO3-δ (x = 0.1, 0.2, PSCFNx) with different Ni doping levels were synthesized. The results showed that increasing Ni doping led to the creation of more oxygen vacancies. Furthermore, treatment of PSCFNx in a reducing atmosphere resulted in a structural transformation into a composite with a heterogeneous interface between the Ruddlesden-Popper perovskite (RP-PSCFNx) and an exsolved Ni-Fe metal alloy. The re-PSCFN0.2-based cell showed a current density of 2.40 A cm−2 and a Faraday efficiency (FE%) of almost 100 % at 850 °C and 1.6 V, an improvement of 18 % in comparison to the re-PSCFN0.1-based cell. This study provides a strategy to synergistically improve the electrochemical reduction of CO2 activity of SOECs by constructing an active heterogeneous interface and increasing the oxygen vacancy content.

Ni-modified BaTiO3 film prepared by sol-gel with high energy storage performance

The development of lead-free dielectric capacitors with high recoverable energy storage density and high energy storage efficiency is important for improving the overall performance of electronic and power systems. BaTiO3 (BTO) is one of the most common ferroelectric materials and has attracted much attention for energy storage applications in the past decades due to its excellent dielectric and ferroelectric properties. However, high remnant polarization and low electrical breakdown strength of BTO limit its development in energy storage applications. Many efforts (e.g., elements doping, interface/heterostructure, etc.) have been made to improve the energy storage density of BTO thin films. In this paper, Ba1-xNixTiO3 thin films (x = 0, 0.02, 0.04, 0.06, 0.08; abbreviated as BNxT) were synthesized via sol-gel and spin-coated method. The effect of Ni doping on the structural, dielectric, ferroelectric and energy storage properties of BTO thin films has been studied. The results confirmed that with the increase of Ni doping, a second phase arises and the dielectric constant decreases. While appropriate Ni doping led to the improvement of the breakdown strength, further increase of Ni deteriorated the energy storage because of the high oxygen vacancy. Finally, optimized energy storage performance was obtained for BN0.04T thin film: dielectric constant of 401, dielectric loss of 0.002, recoverable energy density of 20.2 J/cm3 and energy storage efficiency of 83.6% at 965 kV/cm. Meanwhile, the remnant and maximum polarization of the films were 0.06 μC/cm2 and 50 μC/cm2, respectively. BN0.04T thin film has an excellent application prospect and is expected to appear as a component in the future composite energy storage film system.

Sol–Gel Synthesized Nickel‐Doped Ruthenium Oxide Aerogel for Highly Efficient Acidic Hydrogen Evolution Reaction

Solar and wind energy for water electrolysis are gaining interest in contemporary times. In this context, platinum catalysts are commonly recognized as the standard for the hydrogen evolution reaction (HER), yet their effectiveness is constrained by their high cost and inadequate stability. Combining Ru and Ni lowers the material expense and greatly improves the electrocatalytic performance. Therefore, in the present study, a 3D nanostructured amorphous RuO2 aerogel is doped with various concentrations of Ni for enhanced HER activity. The results indicate that the 4% Ni‐RuO2 aerogel exhibits a 0D colloidal network featuring interconnected mesopores, with a high specific surface area of 241.5 m2·g−1. In addition, the 4% Ni‐RuO2 aerogel catalyst exhibits the lowest overpotentials of 63 and 122 mV at current densities of 10 and 50 mA·cm−2, respectively, along with enhanced hydrogen adsorption activity for the HER due to the 3D porous structure of the aerogel. However, a further increase in Ni doping leads to a decrease in HER activity due to a reduction in the number of catalytic Ru sites. The study found that doping with the optimum amount of Ni causes a redistribution of charges on the sample surface, thereby uncovering more reaction sites and enhancing the electrocatalytic performance.

Theoretical and experimental studies on electronic structure and optical properties of NixTi1-xO2

The effects of Ni-doping on the electronic structure and optical properties of TiO2 were studied. Ni-doping can promote the transformation of rutile to anatase. With the increase of Ni-doping, the band gap gradually decreases and the absorption band edge gradually shifts to the long-wave direction. The energy band structure, electronic density of states and optical properties of Ni-doped TiO2 were investigated using a first-principles plane-wave pseudopotential method based on the framework of density-functional theory (DFT). With the increase of Ni-doping, the band gap of TiO2 gradually decreases. The results of optical properties study is consistent with the experimental results.

Structural, magnetic and optical properties of nickel doped iron oxide nanoparticles based on Logas natural sand for environmental application

The iron oxide nanoparticles have been prepared by mechanical milling method using Logas natural sand as a raw material. The products of ball milling were doped with Ni nanoparticles at different doping concentrations (0, 1, 2, 3, and 4 wt.%). The effect of doping concentration on the structural, magnetic, and optical properties was studied. The structural, magnetic, and optical properties of the prepared samples were studied using an X-ray diffractometer (XRD), vibration sample magnetometer (VSM), and UV-Vis spectroscopy, respectively. The X-ray diffraction pattern shows that the ball milling product is hematite (α-Fe2O3) nanoparticles and highly crystalline with a rhombohedral structure. It is very interesting to find that Ni doping nanoparticles cannot change the structure of iron oxide nanoparticles however, the average crystallite size decreases from 39.43 to 32.64 nm with increasing Ni doping concentration from 0 to 4 wt. %, respectively. The crystallite size based on the dominant peak (104) varies as Ni doping concentration increases. The magnetic properties of the samples show the ferromagnetic nature of the prepared nanoparticles. The saturation, remanence magnetization, and coercivity increase with increasing Ni concentration. The optical band gaps calculated through UV-Vis absorption measurements confirm that the decrease in crystallite size is accompanied by a decrease in the band gap value from 2.03 to 1.92 eV as the doping concentration increases from 0 to 4 wt. %.This study demonstrates the simple way of preparing Ni-doped iron oxide nanoparticles for environmental application.

Influence of Ni over magnetically benign Co ferrite system and study of its structural, optical, and magnetic behaviour

Nickel-substituted cobalt ferrite nanoparticles (NixCo1-xFe2O4, where x = 0.0 to 1.0 with a step size of 0.2) were synthesized using a citrate precursor process and characterized using Scanning Electron Microscopy (SEM), Raman spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-Ray diffraction (XRD) and vibrating sample magnetometry (VSM). XRD confirmed the formation of cubic spinel ferrite nanoparticles for all the samples without any impurity phase. The crystallite size is observed to vary between 39.78 nm and 41.11 nm, whereas the lattice parameters are observed to decrease from 8.369 Å to 8.333 Å with the increase in Ni doping. In the FTIR spectra, two characteristic bands were observed at the octa and tetrahedral sublattices. From the Raman spectra, five Raman active modes (2A1g + Eg + 2T2g) were observed and an inverse (cubic) spinel structure of Ni-Co ferrite nanoparticles was established. The hysteresis curve of NixCo1-xFe2O4 shows the extremely magnetic nature of the nanoparticles whose saturation magnetization, remanence magnetization, and coercivity decrease with nickel doping. The saturation magnetization value (σs) is observed to decrease from 70.18 emu/g to 43.16 emu/g, whereas, the value of coercivity decreases from 2.27 kOe to 0.51 kOe with the increase in Ni doping concentration. The magnetic properties indicate that the prepared nanoparticles can be used for data storage device applications.

Low content Ni-doped BiFeO3 with efficient photo-Fenton degradation of tetracycline

In the present study, Ni-doped BiFeO3 (BiFe1-xNixO3, marked as BFNO, x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) visible light photocatalytic materials were prepared by sol-gel method. It is found that Ni doping could make the BiFeO3 absorption band red-shifted, enhance the absorption of visible light and reduce the bandgap. The photogenerated electron-hole complex of the material was effectively suppressed after Ni doping. Meanwhile, the magnetic measurements indicated that Ni doping could significantly enhance the saturation magnetization of BiFeO3, and the saturation magnetization of the materials increased exponentially with the increase of Ni doping. The photo-Fenton degradation performance of BFNO on tetracycline (TC) was investigated under visible light exposure. It was found that BFNO-8 (BiFe1-xNixO3, x = 0.08) was an effective catalyst for the degradation of TC, and the addition of 4 mmol/L H2O2 and 0.7 g/L of BFNO-8 could improve the degradation rate of TC to 96% within 120 min. The photocatalytic performance of BFNO-8 was so stable that it maintained a high degradation rate of TC even after 4 reuse times. Based on the radical capture experiments and electron paramagnetic resonance (EPR) results, the possible reaction mechanism of TC degradation by BFNO-8 was speculated to be that photocatalysis accelerated the Fe2+/Fe3+ recycling, formed the electron capture center, and accelerated the effective decomposition of H2O2.

Evolution from helical to collinear ferromagnetic order of theEu2+spins inRbEu(Fe1−xNix)4As4

The ground-state magnetic structures of the ${\mathrm{Eu}}^{2+}$ spins in recently discovered $\mathrm{RbEu}{({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Ni}}_{x})}_{4}{\mathrm{As}}_{4}$ superconductors have been investigated by neutron powder diffraction measurements. It is found that as the superconductivity gets suppressed with the increase in Ni doping, the magnetic propagation vector of the Eu sublattice diminishes, corresponding to the decrease in the rotation angle between the moments in neighboring Eu layers. The ferromagnetic Eu layers are helically modulated along the $\mathit{c}$ axis with an incommensurate magnetic propagation vector in both the ferromagnetic superconductor $\mathrm{RbEu}{({\mathrm{Fe}}_{0.95}{\mathrm{Ni}}_{0.05})}_{4}{\mathrm{As}}_{4}$ and the superconducting ferromagnet $\mathrm{RbEu}{({\mathrm{Fe}}_{0.93}{\mathrm{Ni}}_{0.07})}_{4}{\mathrm{As}}_{4}$. Such a helical structure transforms into a purely collinear ferromagnetic structure for nonsuperconducting $\mathrm{RbEu}{({\mathrm{Fe}}_{0.91}{\mathrm{Ni}}_{0.09})}_{4}{\mathrm{As}}_{4}$, with all the ${\mathrm{Eu}}^{2+}$ spins lying along the tetragonal (1 1 0) direction. The evolution from helical to collinear ferromagnetic order of the ${\mathrm{Eu}}^{2+}$ spins with increasing Ni doping is supported by first-principles calculations. The variation of the rotation angle between adjacent ${\mathrm{Eu}}^{2+}$ layers can be well explained by considering the change of magnetic exchange couplings mediated by the indirect Ruderman-Kittel-Kasuya-Yosida interaction.

Synthesis and Characterization of Ni-Doped ZnO Nanoparticles for CO2 Gas Sensing

In this research, we synthesised nickel (Ni)-doped zinc oxide (ZnO) nanoparticles (NZ) with various atomic ratios of [Ni]/[Zn], i.e., 0.02, 0.04 and 0.06 using a simple sol–gel method. The synthesized materials were examined by different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) attached with energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The observed XRD results confirmed that all the prepared samples exhibited a hexagonal wurtzite structure with no additional secondary phases, confirming that Ni ions were successfully incorporated into the lattices of ZnO crystals. The average size of the synthesized nanoparticles is in the range of 30–80 nm, as was confirmed from the TEM observations. The synthesized Ni-doped ZnO nanoparticles were used as functional material to fabricate efficient CO2 gas sensors. The gas detection results demonstrated an improvement in the response of the Ni-doped ZnO sensor towards CO2 gas. The data obtained at 350 ˚C working temperature reveal that this sensor has a modest reaction to CO2. With increasing Ni doping, we noticed that the baseline and the dynamic responses rises. Based on the obtained results, a plausible sensing mechanism towards CO2 gas sensor based on Ni-doped ZnO nanoparticles is also proposed and presented in this paper.

Preparation and Characterization of Nickel Doped Cadmium Sulfide Nanostructure Thin Films via Spray Pyrolysis Method

Pure and nickel-doped cadmium sulphide (NixCd1-xS where x= 2.5%, 5%, 7.5%) nanostructure thin films were successfully prepared by spray pyrolysis method on glass substrate at 350 °C. The films characterized using X-ray crystallography diffractmeter, Scanning Electron Microscope, Atomic Force Microscope and Uv-visible analysis in order to explore the properties of thin film. Structural studies revealed that the deposited films exhibit hexagonal structure with strong intensity at (002) plane. Structural parameters such as crystallite size, strain and dislocation density were calculated for films with different doping concentration. AFM measurements showed that the average diameter increased with increasing Ni doping, where surface roughness and root mean sequre decreased with increasing Ni doping, SEM images show that thin film have been grown and converted into nanowire with increasing of Ni content.Finally, Uv-visible analysis show that the optical band gap of CdS decreased from 2.44 to 2.38 eV with increasing of Ni doping concentrations.

Eg[formula omitted]t2g Sub band splitting via crystal field and band anticrossing interaction in NixCd1-xO thin films

In the present work, full composition range of NixCd1-xO thin films, from Cadmium oxide to Nickel oxide are prepared with sol-gel chemical synthesis route on corning glass substrates. The Fourier transform infrared spectra provide a direct indication of compositional dependence for different vibrational modes with increasing Ni doping. The microscopy images reflect the reduced crystallinity and closely packed morphology with increasing Ni doping which endorses the changes reflected in electronic structure. The O K edge, soft X-ray absorption spectra (XAS) for thin films indicate a clear evidence of eg and t2g sub band splitting and has been explained via crystal field splitting and three level band anti-crossing (BAC) interaction phenomena. At higher doping fraction, the inhomogeneous electric field of neighboring ions surrounding the unfilled Ni 3d level results in rupturing of L−S coupling and further crystal field splitting. The BAC interaction brings about partially unoccupied localized Ni 3d and empty d acceptor levels above conduction band minima (CBM). As saturated Fermi level goes below CBM with increasing Ni doping, transitions to antibonding orbital [eg(π*) and t2g(σ*)] with finite energy difference, is reflected as separated eg-t2g peaks in XAS spectra. On the other hand, extended X-ray absorption fine structure for Ni K edge fitting provides a complete information for nearest (Ni-O) and next nearest (Ni-Ni) neighbor bond length.

Electrochromic Properties of the Vanadium Pentoxide Doped with Nickel as an Ionic Storage Layer

The electrochromic property of nickel doped vanadium pentoxide (V2O5) deposited by a co-sputtering system is investigated. The structural analysis of the thin film was done by an X-ray diffraction (XRD) analyzer. The surface morphology of the film was studied by a field emission scanning electron microscopy (FE-SEM). The composition of the film was detected by an Auger analysis. The electrochromic properties of the device were measured by cyclic voltammetry. For the undoped V2O5 thin film, the charge storage capacity increases with the thickness and is 42.58 mC/cm2 at the thickness of 192.4 nm after 2 h deposition. For the Ni-doped V2O5, the Ni-V-O film shows V2O5 structural dominate with cathode coloration in the lower Ni deposition power region and the charge storage capacity decreases with the increases of the power, while the Ni-V-O film transfers to NiO structural dominate with anodic coloration at the realm of higher Ni doping. The charge storage capacity increases with the increase of Ni doping. It can reach to 101.35 mC/cm2. The Ni-V-O electrochromic film shows improvement of transmittance difference between colored and bleached values and improvement of charge store capacity as it is compared to pure V2O5 films.

Tuning PL emission energy and bandgap with Ni dopant of MgO thin films

In this study, for the first time, the effect of Nickel (Ni) additive on Magnesium oxide (MgO) thin films produced by using successive ionic layer adsorption and reaction technique (SILAR) was investigated. Absorption, photoluminescence (PL), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) measurements were executed to examine how the optical, structural and morphological properties of the samples were affected by the addition of Ni. In the absorption analysis, it was noted that the band gaps of the MgO samples decreased from 4 eV to 3.5 eV with the increase of Ni dopant concentrations. Also, the transmittance values of MgO nanostructures decreases with the increase of Ni contribution, and in the same way, the reflection measurements show that the reflection of MgO decreases with the increase of Ni doping. PL measurements revealed that the fabricated structures radiate around 410 nm and 730 nm. According to XRD measurements, besides the cubic structure of the samples, NiO formations were detected inside the MgO thin film samples due to the increase in Ni dopant. XPS measurements have proven the presence of Ni doping in MgO. SEM measurements showed that all samples exhibited nanowall structure. All these results demonstrate that Ni doping on MgO thin films can be achieved by using SILAR deposition technique.

Optical and room-temperature ferromagnetic properties of Ni-doped CuO nanocrystals prepared via auto-combustion method

The pure and Ni-doped CuO nanocrystals were prepared via auto-combustion method and characterized by X-ray diffraction, scanning electron microscope, UV spectroscopy, and vibrating sample magnetometer method. The X-ray diffraction patterns of all samples revealed the monoclinic CuO nanocrystals with the nanocrystalline phase. XRD data revealed that the lattice constants of CuO nanocrystals were decreased with increasing Ni concentration which indicate that Ni2+ ions incorporated in CuO lattice. The average crystallite size of nanocrystals is intended by Scherer’s formula and found in the range of 21–24 nm. The variation of microstrain was investigated for pure and Ni-doped CuO samples. The SEM images exhibited that the prepared particles have spherical-like structure. The optical absorption spectra of the nanoparticles obtained using UV–Vis spectrophotometer show the blue-shift with increasing Ni doping. The optical band-gap energy increased with increasing Ni doping concentration due to the sp-d exchange interaction between d localized electrons of Ni. Magnetic measurement showed a ferromagnetic behavior at room temperature. Structural and magnetic properties are also discussed in detail.

Magnetic order and fluctuations in the quasi-two-dimensional planar magnet .

We use neutron scattering to investigate spin excitations in , which has a -axis incommensurate helical structure of the two-dimensional (2D) in-plane ferromagnetic (FM) ordered layers for . By comparing the wave vector and energy dependent spin excitations in helical ordered and paramagnetic , we find that Ni doping, while increasing lattice disorder in , enhances quasi-2D FM spin fluctuations. However, our band structure calculations within the combined density functional theory and dynamic mean field theory (DFT+DMFT) failed to generate a correct incommensurate wave vector for the observed helical order from nested Fermi surfaces. Since transport measurements reveal increased in-plane and -axis electrical resistivity with increasing Ni doping and associated lattice disorder, we conclude that the helical magnetic order in may arise from a quantum order-by-disorder mechanism through the itinerant electron mediated Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions.

Characteristics of Ni-doped TiO2 nanorod array films

In this work, un-doped and Ni-doped titanium dioxide nanorod (TiO2 NR) arrays were synthesized by using a hydrothermal method in a Teflon-lined autoclave, on a fluorine tin oxide (FTO) substrate, at different Ni content (XNi = 0, 0.025, 0.05, 0.075, and 0.1). The grown nanorod array samples were studied by XRD, FESEM, DC conductivity, Hall effect measurements, ultraviolet-visible (UV-Vis) spectroscopy, and vibrating-sample magnetometer (VSM) measurements. Pure rutile phase with preferred orientation along (002) was noticed, indicating that the vertical growth of nanorods for the un-doped sample converts to the (101) direction with increasing doping content. The sharp (002) peaks compared with the broad behavior for other peaks indicate the longitudinal growth along this direction. The lattice constant (a), for tetragonal structure, increased with increasing Ni content, while small increment showed along the (c) direction. Uniformly distributed nanorod arrays with 2000-nm length and 200-nm diameter for the un-doped sample. The nanorod length decreases and their diameters increase with increasing Ni doping content. All the prepared samples showed that they behave like n-type semiconductors with a high carrier concentration and this can be attributed to the present of oxygen vacancies. DC conductivity increases due to increasing carrier concentration, while the charge carriers’ mobility decreases with increasing doping content from 0 to 0.1. Increasing Ni content enhances the TiO2 NR magnetic properties, where the residual magnetization increased from 0.0001 to 0.0058 emu/g, while the saturation magnetization increased from 0.0304 to 0.2652 emu/g with increasing Ni content from 0 to 0.1.

Correlation between structure, dielectric and multiferroic properties of lead free Ni modified BaTiO3 solid solution

Present study highlights the influence of Ni doping on the structural, optical, dielectric, ferroelectric and magnetic properties of nanocrystalline BaTi1-xNixO3 (0 ≤ x ≤ 0.06) ceramics synthesized by sol-gel auto combustion process. Phase identification and crystal structure are examined through Rietveld refinement analysis that ensures mono-phase nature with tetragonal crystal structure in P4mm space group. The observed variation in the structural parameters viz. lattice constants, unit cell volume, bond lengths (Ti-O) and bond angles (Ti-O-Ti) are the direct evidence of distortion produce in the unit cell under the effect of Ni doping. The FTIR studies confirm perovskite structure and presence of stretching/bending vibrations of the various bands present in the samples. The optical properties divulge a minor alteration in optical bandgap under the influence of Ni content. Dielectric studies reveal higher value of the dielectric constant for pristine sample in the low frequency region, but its value decreases on Ni doping. The dielectric response, analyzed through UDR model, exhibits deviation from linear behavior at higher frequencies. Ferroelectric measurements demonstrate that the pristine sample has higher values of remnant polarization (Pr) and maximum polarization (Pm) which decrease linearly with the increase in Ni doping. Magnetic hysteresis loops at room temperature establish a weak ferromagnetic nature of the samples that arises due to the carrier-mediated exchange interactions with smaller values of magnetic parameters. These investigations ensure that the ferromagnetism can be induced in BaTiO3 by appropriate doping of Ni ions, which may find their potential use in the field of multiferroics.