This paper explores the potential application of titanium dioxide ( TiO_2 ) nanoparticles (NPs) to enhance the performance of Schottky barrier diode (SBD) made from vanadyl 2, 9, 16, 23-tetraphenoxy-29H, 31H-Phthalocyanine (VOPcPhO), a small-molecule organic semiconductor. The SBD is fabricated using a facile spin coating technique at ambient conditions by casting a 1:1 vol TiO_2 NPs in chloroform on pre-deposited Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on an indium tin oxide (ITO) substrate. To analyze the electronic properties of the fabricated device, current–voltage ( I-V ) measurements are performed at 25 ^∘ C in dark conditions. The I-V characteristics of SBD displayed asymmetrical behavior with rectification ratio (RR) of 261 at ± 2.1 V for ITO/PEDOT:PSS/VOPcPhO– TiO_2 /Ag device which indicates the formation of a depletion region. Key electronic parameters such as charge carrier mobility ( μ ), barrier height ( ϕ _b ), series resistance ( R_s ), and ideality factor (n) are derived from the I-V curves. Norde’s and Cheung’s methods are also used to verify the consistency of these parameters. Significant improvements in the values of R_s , n and RR are observed in ITO/PEDOT:PSS/VOPcPhO– TiO_2 /Ag device compared to many other Schottky barrier diodes (SBDs). This enhancement is attributed to the incorporation of TiO_2 nanoparticles which provide high surface-to-volume ratio. Additionally, the conduction mechanism in the fabricated device is analyzed by focusing on Poole–Frenkel and Richardson Schottky effects. The paper also reports Ultraviolet–Visible spectroscopy (UV–Vis) to obtain optical bandgaps (1.9 and 3.4 eV), morphology such as atomic force microscopy (AFM) and scanning electron microscopy (SEM) for high-resolution surface investigation, X-ray diffraction (XRD) for the determination of material’s crystallinity and Fourier transformed infrared (FTIR) for functional group analysis of VOPcPhO– TiO_2 nanoparticles.

Aramid fiber–reinforced polymer composite (AFRPC) is popular in aerospace and defense industries owing to its superior thermal and mechanical properties. However, its intricate hexagonal cellular structure and the material’s heterogeneous, soft, and brittle characteristics lead to significant surface defects, such as burr formation, wall tearing, roughness, dimensional inaccuracies, and uncut fibers during traditional machining. Such poor machining quality issues notably affect the operational lifespan and functional performance of its sandwich structural components. To address these issues, the rotary ultrasonic assisted machining (RUSAM) process has been introduced. To thoroughly investigate the RUSAM of AFRPC using various cutting tools, a 3D finite element model was developed and validated. This paper mainly investigates the effect of various machining parameters such as vibration amplitude (VA), cutting width (CW), feed rate (FR), and spindle speed (SS) on the cutting force, surface morphology, burr formation, and burr height during RUSAM of AFRPC structure by plane and toothed disc cutters. The burr height was found to decrease with the increase of spindle speed (60.82 149.81% and 321.16 L_16 ( 4^4 ) experiments revealed the cutting width to be the most influential parameter on the burr height and cutting force followed by the spindle speed, feed rate, and vibration amplitude during RUSAM of the AFRPC core by the disc cutters. Up to 62.54% reduction in burr height was realized by rotary ultrasonic assisted machining compared to the conventional machining. Under specified operating conditions, the disc cutter generates a higher but less number of burr as compared to the toothed disc cutter without any tearing defects. 3–10

Nomex honeycomb composite (NHC) has been increasingly used in the automotive, aerospace and defence applications due to its excellent thermal and mechanical properties. Its complex cellular hexagonal thin-walled configuration along with heterogeneous, soft and brittle nature pose substantial processing defects such as burr formation, tearing of walls, surface roughness, dimensional inaccuracy and low machining quality during conventional machining (CM). These surface defects have a substantial influence on the operating life and functional performance of its sandwiched structural members. Hybrid ultrasonic vibration assisted machining (HUSVAM) technology has been introduced to overcome such limitations. For an in depth research on HUSVAM of NHC using ultrasonic toothed disc cutter (UTDC), three dimensional finite element model was developed and experimental validation was carried out. The numerical simulation and experimental results were found to be in good agreement with one another. The influence of various machining parameters including the ultrasonic tool vibration amplitude (UTVA), feed rate (FR), depth of cut (DoC) and spindle angular speed (SAS) on NHC cutting forces, chip formation and surface quality was investigated using both HUSVAM and CM techniques. Furthermore, stresses, deformation and forces near tool-workpiece interaction along with the surface topography and morphologies were also analysed and compared for various operating conditions. A reduction in the cutting forces was found with the increase of SAS and UTVA (up to 65.47 % and 65.74 %, respectively). Although, the cutting forces were observed to increase by increasing the DoC and FR (up to 159.45 % and 126.33 %, respectively). DoC has a greater impact on the cutting forces among all machining parameters according to 4 levels, 4 factors (L-16) orthogonal experiments based on Taguchi method. The results show that the chip formation and machining quality of NHC core can be improved with HUSVAM technique using UTDC. HUSVAM also reduced the cutting forces (up to 73 %) compared to CM. The ultrasonic toothed disc cutter generated large number of burr with very short length, no tearing defects and no uncut fibers as observed from scanning electron microscopy of NHC hexagonal cell structure, walls and triple points. A burr formation of less than 10 % was realized during HUSVAM of NHC cores for F-x <= 3N, while it was found up to 20 % if F-x > 3N, compared to at least 40 % during CM. The finite element model developed can be used to investigate the influence of HUSVAM on modern difficult to machine materials for enhanced surface quality.

High entropy alloys possess excellent properties and a great deal of research is being carried out on them. AlCrCo(1-x)Fe(1+x)Ni2 (x= 0, 0.5, 1) alloys were arc melted and suction cast in strip form in a controlled atmosphere. The alloys were characterized for crystal structure, phases and Vickers hardness. A two phase vermicular structure was observed for alloys with x = 0 – 0.5 consisting of Ni rich BCC and Cr rich FCC phases while a widmanstatten structure formed in alloy with x = 1 (without Co). An increase in the amount of BCC phase and hardness was noted with the replacement of Co with Fe caused mainly due to increase in Al and decrease of Cr in composition obtained through EDS. Vickers hardness of 251 HV was measured in alloy without Co.

Ultrasonic horn plays a vital role in achieving vibration amplitude at tool end (VATE) by enhancing output displacement of piezoelectric ultrasonic transducer suitable for efficient machining of advanced composites. Higher vibration amplitude enhances ultrasonic machining quality, surface integrity and dimensional accuracy of Nomex honeycomb composite (NHC) while reducing cutting forces. Furthermore, low stress concentrations allow ultrasonic tool to have more safety factor and longevity. Ultrasonic horn is designed to enhance displacement amplitude of piezoelectric ultrasonic transducer and get optimum VATE while keeping stresses in acceptable limits to avoid failure at very high operating frequency of ultrasonic machining system. In this research, variety of standard ultrasonic horns (SUH) were designed with same length and end diameters; and were tested under similar operating conditions, using finite element method. The ultrasonic actuation of the horn exploits the first axial mode of horn vibration. Harmonic response analysis was carried out to determine axial modal frequencies (AMF), VATE, stresses, and factor of safety for performance evaluation. VATE attained by step horn was found to be greatest among all other SUHs for frequency ratio greater than one, but may be prone to early failure due to high stress concentrations. VATE achieved by third order Bezier, Gaussian, exponential, catenoidal, conical and second order Bezier horns were found less than that of step horn by 11.7 %, 16.6 %, 16.7 %, 17 %, 16.73 % and 18 % respectively. However, 44.2 %, 43.43 %, 42.5 %, 43.5 %, 42.8 % and 37.67 % reduction of stresses was achieved by Gaussian, exponential, catenoidal, conical, second and third order Bezier horns respectively. Outcomes of present work would be beneficial for designers, researchers, scientists, and manufacturers of ultrasonic machine tool to select appropriate SUH designs according to requirements.

In this work, polypyrrole (PPy) is synthesized, characterized, and employed as an active sensing material for the fabrication of humidity sensors. An 80 nm thick layer of PPy is spin coated on the pre-patterned thermally deposited silver (Ag) electrodes spaced 50 µm apart to fabricate Ag/PPy/Ag surface-type sensor. Atomic force microscopy analysis revealed granular microstructure morphology in the thin films of PPy. Additionally, X-ray diffraction (XRD), ultraviolet–visible (UV-Vis) and Fourier transformed infrared (FTIR) spectra of PPy are analyzed to study its crystallinity, optical bandgap and bond dynamics to confirm the molecular composition of PPy. The fabricated Ag/PPy/Ag sensor is characterized by varying the humidity levels between a broad range [0–95

Ultrasonic horn (USH) is a key component in high intensity power ultrasonic systems to enhance vibration amplitude at tool end (VATE). Due to high intensity ultrasonic operating frequency of at least, horn may be exposed to high stress levels leading to failure. The primary objective of USH design is to achieve high vibration amplification with good strength. In present research, the effect of fillet radius / roundness on ultrasonic composite horn (USCH) performance was investigated for various materials: stainless steel, aluminum, titanium, and steel, respectively, using finite element analysis (FEA). USCH was developed for ultrasonic machining of soft and brittle composites, especially Nomex honeycomb composite. The important performance parameters considered were longitudinal modal frequency (LMF), Von Mises (VM) stresses, magnification factor (MF), VATE and factor of safety (FS). LMF was found to increase, with decrease in VATE and VM stresses by increasing the roundness at the transition section. Titanium was observed to be highly appropriate material for USCH, because it delivered at least 81.6 % to 142.62 % more vibration amplification and up to 4 times higher factor of safety, consequently, operating life in comparison to other USCH materials.

Utilization of advanced hard and brittle materials in engineering applications has led to the need of non-conventional machining techniques such as rotary ultrasonic machining (RUM) to achieve high dimensional accuracy and low machining defects (delamination, burr and cracks formation, etc.). RUM performance greatly depends on vibration amplitude at tool end which is achieved through appropriate ultrasonic horn design. Longitudinal–torsional coupled (LTC) vibrations, generated by incorporating helical slots in horn design, improve ultrasonic machining quality of hard and brittle materials. In present investigative work, modified ultrasonic horns were designed and analyzed for RUM by producing helical slots in quadratic and cubic Bezier horn profiles to achieve high amplitude ratio ( T_ A/L_ A ) within safe stress limits. Modal and harmonic analyses were performed to investigate the influence of depth ( D_ s ), width ( W_ s ), angle ( θ_ s ) and location ( L_sp ) of helical slots on the modal frequencies, vibration amplitudes, torsional to longitudinal amplitude ratio and stresses in ultrasonic LTC Bezier horns using FEM. Modified ultrasonic horns were tested for three different materials: steel, aluminum, and titanium after validation with available literature. Presently designed horns were found to attain high amplitude ratio and low stresses as compared to the commercial step LTC horn for same end diameters and length. Different stresses (shear, von Mises, radial, tangential and axial) were also computed and plotted along horn axial length for optimum designs and were found well below the endurance limit. For the same end conditions and length, cubic Bezier LTC ultrasonic horn is preferable to its quadratic counterpart due to 19.91% higher amplitude ratio. However, stresses are 24.78% less in quadratic Bezier LTC ultrasonic horn. The amplitude ratio attained by both types of LTC Bezier horns was found to be significantly greater than that in the commercial LTC step horn, with additional advantage of low stresses. Achievement of high amplitude ratio will help in reduced cutting force and improved surface quality of advanced hard and brittle materials as compared to standard LTC horn design.

The applications of Nomex honeycomb composite (NHC) structures in aerospace, automotive and defence sectors have been significantly increasing due to their high compressive strength, hexagonal thin-walled structure, ultra-light weight and excellent thermal resistance. Specific applications include composite sandwich structures in helicopter propellers, satellite cabins, aeroplane floors, engine cowls, wings and nacelles. Accuracy of the machined surface of NHC structures is required for adhesive bonding with face-sheets. Conventional machining processes generate machining defects in terms of tearing, damaged cell walls, burr formation, delamination and poor surface quality that result in reduction of strengths of the core structure and its bond with face sheet. Ultrasonic machining is a proven technique to overcome such machining defects and improve the surface quality of NHC structures. Novelty of this research includes the development of a three-dimensional (3D) finite element model to analyse cutting forces, chip formation and machining quality of NHC structures using disc cutter through both ultrasonic and conventional machining processes by providing feed to the workpiece instead of the cutting tool. The significant influence of machining parameters such as depth of cut, feed rate, ultrasonic amplitude and spindle speed on cutting forces was investigated numerically followed by experimental validation. Numerical model in support with experimental results show that cutting forces decrease by increasing ultrasonic amplitude and spindle speed (up to 54.74 F_y≤ 3 N , while it was found up to 10 F_y>3 N , compared to at least 30

Ultrasonic Welding has emerged as a sustainable, green, and efficient manufacturing technology. This technique joins unique and advanced materials quickly, with good welding quality through high-intensity vibrations. Ultrasonic welding uses relatively low energy and incurs lower costs compared to various conventional welding systems. One of the key aspects to ensure high welding quality and strength, along with the transmission of high forces, is the design of an efficient ultrasonic sonotrode. This research study is aimed at proposing, evaluating, and testing the design of a tubular cubic polynomial sonotrode using finite element analysis. This novel ultrasonic welding sonotrode operates with low stresses and high displacement amplification. The performance of the proposed ultrasonic welding sonotrode design was compared with the commercially popular sonotrode, as well as cubic Bezier, exponential, and conical designs. This comparison was done in terms of harmonic excitation response, stresses, axial stiffness, displacement amplification, and factor of safety. The performance characteristics were also evaluated along the sonotrode length. The proposed sonotrode was found to be superior in terms of high vibration amplification and axial stiffness within safe stress limits. The benefits of the flexible design as per requirement to attain a higher displacement amplitude at the output end; consequently, lower welding forces were also realized. The proposed design is an improvement towards an efficient and green manufacturing technology involving reduced cost, energy consumption, use of consumables, effort, waste generation, and harm to the environment.

Ultrasonic horn is utilized in order to enhance the amplitude of vibration transmitted by the transducer in an ultrasonic machining system. It plays a vital role in vibration amplification to a magnitude suitable for efficient machining of materials. Ultrasonic machining system has to operate at a frequency of at least. Therefore, horn may be subjected to high magnitude of stresses leading to failure. Mechanical horn is designed to get optimum vibration amplification while keeping stresses in acceptable limits. In this research an ultrasonic compound horn was designed with through cutout of uniform diameter. The performance of ultrasonic horn was observed by varying the cutout diameter by modelling horns of four different materials: titanium, aluminum, steel and stainless steel respectively. Modal analysis was performed for computing modal frequencies in the axial direction, whereas harmonic analysis was carried out in order to determine vibration amplitude, stresses and factor of safety. The effect of varying frequency ratio on vibration magnification, stresses, and factor of safety were also investigated. The axial modal frequency was observed to increase, whereas amplitude of vibration and stresses were observed to decrease by increasing the cutout size. Titanium was found to be the most suitable material for ultrasonic horns, because it provided up to 159.4 % more amplitude of vibration and 3 times higher safety factor thus operating life as compared to other materials.

Ultrasonic horn is utilized to enhance vibration amplitude transmitted by the transducer in an ultrasonic machining system. It plays a vital role in vibration amplification to a magnitude suitable for efficient machining of materials. Ultrasonic machining system has to operate at a frequency of at least 20kHz. Therefore, ultrasonic horn might be exposed to great magnitude of stresses causing early failure. Ultrasonic horn is usually developed to achieve high magnification factor and displacement amplitude with acceptable stress concentrations. In this research an ultrasonic horn was designed with Bezier profile having through hole of uniform diameter. Modal analysis was carried out to determine resonant frequencies in the axial direction, while stresses, displacement amplitude and safety factor were computed through harmonic analysis. The effect of varying hole length on modal frequency, vibration magnification, stresses, and factor of safety were also investigated. Axial modal frequency, vibration amplitude and Von Mises stresses were found to increase, whereas factor of safety was observed to decrease by increasing the hole length. Newly designed ultrasonic horns were able to provide larger magnification factor, high operating life and low stress concentrations in comparison to standard ultrasonic horns.

Ultrasonic horn plays vital role in achieving vibration amplitude suitable for efficient machining of advanced composites. Due to very high operating frequency of at least of ultrasonic machining system, horn may be subjected to high stresses leading to failure. Mechanical horn is designed to get optimum vibration amplification while keeping stresses in acceptable limits. In this research, state of the art ultrasonic horns were designed with same length and diameters at the transducer side and tool ends under similar operating conditions. All standard and hybrid ultrasonic horns, including some new designs, suitable for machining applications were evaluated through finite element analysis. Modal analysis was performed for computing axial modal frequencies, whereas harmonic analysis was carried out to determine vibration amplitude, stresses and factor of safety. The performance of state of the art ultrasonic horn designs were later compared in terms of vibration amplification, stresses and operating life. The axial modal frequency and amplitude of vibration achieved by barrel, cylindrical-double conical and hollow exponential horns were observed to be greater as compared to the step horn, however the former were prone to greater stress concentrations and low operating life. Reasonably higher vibration amplification, factor of safety and low stresses were achieved by Bezier, cylindrical-catenoidal, cylindrical-Bezier, step-conical, step-catenoidal, step-Bezier, double conical, multistep and multistep-conical horn designs. Remarkably, circular hollow exponential and multistep-conical ultrasonic horns were observed to achieve vibration amplification, factor of safety and operating life higher than that of commercially available step horn.

Background: The development of new bioimplants with enhanced mechanical and biomedical properties have great impetus for researchers in the field of biomaterials. Metallic materials such as stainless steel 316L (SS316L), applied for bioimplants are compatible to the human osteoblast cells and bear good toughness. However, they suffer by corrosion and their elastic moduli are very high than the application where they need to be used. On the other hand, ceramics such as hydroxyapatite (HAP), is biocompatible as well as bioactive material and helps in bone grafting during the course of bone recovery, it has the inherent brittle nature and low fracture toughness. Therefore, to overcome these issues, a hybrid combination of HAP, SS316L and carbon nanotubes (CNTs) has been synthesized and characterized in the present investigation. Methods: CNTs were acid treated to functionalize their surface and cleaned prior their addition to the composites. The mixing of nano-hydroxyapatite (HAPn), SS316L and CNTs was carried out by nitrogen gas purging followed by the ball milling to insure the homogeneous mixing of the powders. In three compositions, monolithic HAPn, nanocomposites of CNTs reinforced HAPn, and hybrid nanocomposites of CNTs and SS316L reinforced HAPn has been fabricated by spark plasma sintering (SPS) technique. Results: SEM analysis of SPS samples showed enhanced sintering of HAP-CNT nanocomposites, which also showed significant sintering behavior when combined with SS316L. Good densification was achieved in the nanocomposites. No phase change was observed for HAP at relatively higher sintering temperatures (1100°C) of SPS and tricalcium phosphate phase was not detected by XRD analysis. This represents the characteristic advantage with enhanced sintering behavior by SPS technique. Fracture toughness was found to increase with the addition of CNTs and SS316L in HAPn, while hardness initially enhanced with the addition of nonreinforcement (CNTs) in HAPn and then decrease for HAPn-CNT-SS316L hybrid nanocomposites due to presence of SS316L. Conclusion: A homogeneous distribution of CNTs and SPS technique resulted in the improved mechanical properties for HAPn-CNT-SS316L hybrid nanocomposites than other composites and suggested their application as bioimplant materials.

Nickel titanium (NiTi) shape memory alloys have a vigorous prospective for biomedical solicitations. In this work, electrochemical behavior of hydroxyapatite (HA) coated and thermally oxidized near equiatomic NiTi shape memory alloys was efficaciously investigated for biomedical applications. NiTi samples were spin-coated with laboratory-synthesized HA followed by drying and calcination at 120 ± 5 °C and 450 ± 5 °C, respectively. Similarly, uncoated NiTi samples were thermally oxidized by heating at 450 ± 5 °C in air. The comparison was made among HA-coated, thermally oxidized and uncoated samples. Scanning electron microscope (SEM), atomic force microscope and X-ray diffraction confirm the presence of Titania and HA coating on the NiTi substrates. Electrochemical testing results showed the better resistance against corrosion for the HA-coated samples because of the protective coatings of HA and Titania, as compared to the rest. Moreover, Fourier transform infrared spectroscopy and SEM reveal that the HA-coated sample will provide bioactive cushion to the host structure for better adhesion during the implanted period, while the implant will do its job.

The effect of addition of gold (Au) on the structure and mechanical properties of (Fe0.5Co0.5)71Nb4Si5B20 BMG alloy was studied. Addition of Au formed crystals in the BMG alloy. Gradual increase in the amount of Au added to the BMG alloy resulted in an increase in the amount of crystallinity and hardness of the alloy. Hardness values in excess of 1100 HV were found in all the alloys with a maximum value of 1245 HV. The thermal transition temperatures were also found to increase with an increasing amount of Au. Corner cracks were produced in the alloy with 1.5 at.-% Au content showing a low indentation fracture toughness value of 2.98 MPa-m0.5.

Currently, there is a rising demand to develop composite materials with outstanding tribological properties along with excellent thermal-mechanical properties for harsh tribological applications. In view of this demand, the tribological behaviour of spark plasma sintered (SPS) nano-alumina (similar to 150 nm)-based composites reinforced with 10, 20 and 30.wt.% uncoated and nickel-coated cubic boron nitride (cBN) particles was evaluated using a ball-on-disc configuration against three different counterface materials (WC, Si3N4 and Al2O3) under dry sliding conditions. A variety of techniques were used to evaluate the phase composition and to study the dispersion, wear behaviour and wear mechanisms. The nano-alumina composites exhibited improved wear resistance and coefficient of friction (COF). These results were attributed to the unique combination and uniform dispersion of the reinforcing particles within the composites. Moreover, Ni-coated cBN particles displayed high wear resistance, primarily due to the excellent interfacial bonding provided by the nickel coating. The wear resistance of the sample reinforced with 30% cBN-Ni was improved by at least 85%. The wear mechanisms involved during sliding wear were abrasion, matrix grain pullout (dislodgement of matrix material), microcracking, chipping, and tribolayer formation. (C) 2019 The Authors. Published by Elsevier B.V.

Heat treatment of ceramics is an important process to tailor the fine electromechanical properties. To explore the criteria for optimized heat treatment in a perovskite structure of (1– x )Bi 1.05 FeO 3 – x BaTiO 3 (BF–BT100 x ) system, the structural phase relation, ferroelectric and piezoelectric response of BF–BT36 and BF–BT40 ceramics prepared by furnace cooling (FC) and quenching process were investigated. The X-ray diffraction examination showed single pseudocubic perovskite structure for all the ceramics. The homogenous microstructure was obtained for all ceramics with relatively large grain size in the furnace cooled samples. Well saturated ferroelectric hysteresis loops and enhanced piezoelectric constant ( d 33 = 97 pC/N) were achieved by quenching process. Dielectric curve of BF–BT36 showed large dielectric constant at its Curie temperature, however, BF–BT40 showed diffused relaxor-like dielectric anomalies. Quenched BF–BT36 samples showed typical butterfly like field induced strain curves, however negative strain decreased in BF–BT40 ceramics. From these investigated study, it is observed that BF–BT ceramics are very sensitive to the heat treatment process (furnace cooling and quenching) on the dielectric, electromechanical properties.

Heat treatment of ceramics is an important process to tailor the fine electromechanical properties. To explore the criteria for optimized heat treatment in a perovskite structure of (1–x)Bi1.05FeO3–xBaTiO3 (BF–BT100x) system, the structural phase relation, ferroelectric and piezoelectric response of BF–BT36 and BF–BT40 ceramics prepared by furnace cooling (FC) and quenching process were investigated. The X-ray diffraction examination showed single pseudocubic perovskite structure for all the ceramics. The homogenous microstructure was obtained for all ceramics with relatively large grain size in the furnace cooled samples. Well saturated ferroelectric hysteresis loops and enhanced piezoelectric constant (d33 = 97 pC/N) were achieved by quenching process. Dielectric curve of BF–BT36 showed large dielectric constant at its Curie temperature, however, BF–BT40 showed diffused relaxor-like dielectric anomalies. Quenched BF–BT36 samples showed typical butterfly like field induced strain curves, however negative strain decreased in BF–BT40 ceramics. From these investigated study, it is observed that BF–BT ceramics are very sensitive to the heat treatment process (furnace cooling and quenching) on the dielectric, electromechanical properties.

M-type barium hexaferrite ceramics have emerged as important materials both for technological and commercial applications. However, limited work has been reported regarding the investigation of nanocrystalline Ni-doped barium hexaferrites. In this study, nanocrystalline barium hexaferrite ceramics with the composition BaFe12−xNi x O19 (where x = 0, 0.3 and 0.5) were synthesized by sol–gel method and characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, vibrating sample magnetometer and precision impedance analyzer. All the synthesized samples had single magnetoplumbite phase having space group P63/mmc showing the successful substitution of Ni in BaFe12O19 without the formation of any impurity phase. Average grain size of undoped samples was around 120 nm which increased slightly with the addition of Ni. Saturation magnetization (Ms) and remnant magnetization (Mr) increased with the addition of Ni, however, coercivity (Hc) decreased with the increase in Ni from x = 0 to x = 0.5. Real and imaginary parts of permittivity decreased with the increasing frequency and increased with Ni content. Dielectric loss and conductivity showed slight variation with the increase in Ni concentration.