Temperature Coefficient Of Resistance Behavior Research Articles

Structural, microstructural, dielectric, electrical, and magnetic properties of a scandium-modified bismuth ferrite

ABSTRACT This paper reports on the synthesis method and characterisation of a binary polycrystalline material (Pb0.6Bi0.2Sc0.2)(Fe0.4Ti0.6)O3 ceramic. The room temperature XRD pattern confirms an orthorhombic crystal structure with average crystallite size of 25.3 nm. Study on SEM micrograph reveals the homogeneous dispersal of grains and well-defined grain boundaries and also the compactness of the grains implies the development of a highly dense material. The purity and composition of this material are verified using EDX, and confirms presence of all the constituent elements (Pb, Bi, Sc, Fe, Ti, and O) both in weight and atomic percentage. According to research on dielectric spectra as a function of temperature range of 25°C to 500°C and frequency range of 1 kHz to 1 MHz, there may be Maxwell–Wagner-type dispersion at low frequencies, which considerably decreases towards higher frequencies because of decreasing space charge polarisation. The negative temperature coefficient of resistance behaviour is observed from impedance spectroscopy. The research of modulus spectroscopy demonstrates the existence of a non-Debye type of relaxation. The thermally activated charge carriers regulate the study of the conduction mechanism. The semicircular arcs found both in Nyquist and Cole–Cole plots provide an evidence for the semiconducting nature. The magnetic study reveals the superparamagnetic nature of the sample.

Electrical Transport Properties and Hopping Mechanism of ZrCuSiAs Type Compound GdFeAsO

Abstract Iron-based ceramic GdFeAsO has been prepared using the solid-state reaction method. This material exhibits unique properties, showing superconductivity at extremely low temperatures and behaving as a semiconductor at high temperatures. Raman spectroscopy revealed various Raman active modes in the sample. UV-visible spectroscopy was employed to study the optical properties of the material in the wavelength range of 200-800 nm. Using Tauc's plot, the optical band energy values of the sample were estimated to be approximately 2.78 eV. The electrical characterizations have been performed through an impedance analyzer. Additionally, the sample displayed negative temperature coefficient of resistance behavior and positive temperature coefficient resistance. The thermistor parameters are evaluated using the bulk resistance at various temperatures. This opens up potential uses for thermistors in devices like fuses and temperature sensors. The ac conductivity spectrum of the sample followed both Jonscher's universal power law and the Arrhenius equation. The activation energy was calculated for different temperature regions. The correlated barrier hopping model is used to analyze the electrical conduction mechanism in the sample. This study provides insights into the unique electrical and optical properties of the GdFeAsO ceramic and sheds light on its potential applications in various fields.

Structural, dielectric and electrical transport properties of thermal stable (1-x)K0.5Bi0.5TiO3-xBaTiO3 ceramics

Polycrystalline samples of (1-x)K0.5Bi0.5TiO3 - xBaTiO3 [(1-x)KBT - xBT] were synthesized using a solid-state reaction pathway. X-ray diffraction analysis confirmed the presence of a single-phase perovskite structure. To explore relaxation and conduction mechanisms, complex impedance spectroscopy was employed. Reduction in Curie temperature was observed as BT content increased. The grain and grain boundary contributions to relaxation was examined through complex impedance and modulus plots and quantified via fitting experimental data to an equivalent circuit model. Examination of the Complex impedance spectra uncovered the existence of dielectric relaxation characteristic of a non-Debye nature. Furthermore, the activation energy determined suggests commonalities in governing the conduction and relaxation processes in relation to temperature-dependent conductivity and relaxation time. A negative temperature coefficient of resistance behaviour was obtained from the temperature-dependent conductive study. Dielectric spectra revealed that these ceramic capacitors are useful in reduction of signal interference, signal attenuation and impedance matching circuits applications.

Studies of structural, dielectric, electrical, and optical properties of a multi-doped novel complex perovskite (Bi1/2Na1/2)(Fe1/3Mn1/3W1/3)O3 ceramic for opto-electronic application

(Bi1/2Na1/2)(Fe1/3Mn1/3W1/3)O3 is a new complex perovskite compound synthesized by a solid-state method. A preliminary structural study using the X-ray diffraction (XRD) pattern shows the monoclinic symmetry of the material. The scanning electron microscope (SEM) micrograph shows the dense microstructure or morphology of rectangular shape grains of different dimensions. The purity and elemental composition of the compound were obtained by energy dispersive X-ray (EDX and EDS) spectrum. The analysis of frequency and temperature-dependent relative dielectric constant (εr) impedance and ac conductivity (σac) predict the presence of Maxwell-Wagner type of dielectric dispersion and thermally activated relaxation mechanism. In-depth analysis of impedance and associated factors reveals that they are substantially dependent on temperature and have a significant link with their microstructures. Similar to semiconductors, the nature of impedance spectra displays a negative temperature coefficient of resistance behavior. The electric polarization hysteresis loop shows the ferroelectric behavior and explores the possible applications. The band gap (Eg) is found to be 2.40 eV using the UV-visible spectrum, appropriate for solar and optoelectronic applications. The value of super-capacitance is 58.96 F/g, applicable for an electrode material supercapacitor application. The behavior of leakage currents has also been investigated and found that conduction has been identified as a space-charge conduction mechanism. We are very interested in designing and manufacturing novel dielectric ceramics because of the rising need for the miniaturization of electronic components and the flexibility of applications. Sensors, actuators, transducers, and capacitors are among the most prevalent applications of such types of materials.

Electrical conductivity study of BaSb4Ti4O15 compound

The lead-free compound of antimony-based new layered structure BaSb4Ti4O15 compound is synthesised by high-temperature conventional technique with a calcination temperature of 830 °C. The analysis of X-ray diffraction data shows that the compound had a single-phase orthorhombic crystal system. The scanning electron microscopic analysis of the samples shows a uniform distribution of grains with a smaller number of voids on the surface of the pellet. Generally, different computerized software are used for structural analysis taking powder XRD data. In the process we have attempted to use Jana2006, Qualx, Profex, POWDMULT, FullProf Suit, MAUD and EXPO etc. softwares. It has been found that different softwares give different results. The analysis of structural parameters looks more reliable and consistent with other physical parameters. However, the other possibilities of the structure with large number of experimental data cannot be ruled out. The electrical conductivity of the compound is studied with the help of complex impedance spectroscopy in the frequency range of 1 kHz–103 kHz and temperature range from 30 °C to 500 °C. The conduction process is a thermally activated phenomenon, which is confirmed by AC conductivity versus absolute temperature graphs. The process of conduction in the studied compound is electronic in lower temperatures and conductivity is due to the hoping of the ions at higher temperatures. The conduction process is due to the hopping and non-Debye type which is confirmed by Jonscher’s universal power law. A study of both AC and DC conductivity study informs the negative temperature coefficient of resistance behaviour. The finding here broadens the family of Sb-modified layered structured material which was a class of ferroelectric with good conductivity values with possible application in the field of optoelectronics as well as in perovskite solar cell.

Negative temperature co-efficient of resistance behaviour of Cr doped ZnO nanoceramics

Here, High Energy Ball Milling (HEBM) is used to prepare Cr doped ZnO (Zn1-xCrxO, x = 0–0.04) nanoceramics and their electrical behaviour is studied in detail. The X-ray diffraction suggests a hexagonal wurtzite structure. The Rietveld refinement XRD pattern of the sample calcined at 900 °C suggests that up to 4 at% of Cr can be doped into the ZnO structure. After sintering, the growth in the particle size was observed for Cr doped ZnO samples. The complex impedance behaviour of samples suggests a decrease in resistance with temperature. This shows the Negative Temperature Coefficient of Resistance (NTCR) characteristic of the Cr doped ZnO sample in the studied temperature range (300–500 °C). At higher temperature, the electrical relaxation behaviour is of the non-Debye type as observed from the relaxation time distribution. The equivalent electrical circuit of ZnO and Cr doped ZnO ceramic samples are a parallel arrangement of bulk capacitance (Cb) and bulk resistance (Rb).

Structural and Electrical Transport Features of Bi4Ti2.9Zr0.1O12

This paper reports the structural, dielectric, and electrical properties of Zr (10%) substituted bismuth titanate with the chemical formula Bi4Ti2.9Zr0.1O12. The material possesses a distorted orthorhombic structure and space group of B2cb at room temperature. The Zr-substituted bismuth titanate has a high Curie temperature and good dielectric constant. In any case, the dielectric constant of the Zr doped ceramic is higher than that of pure bismuth titanate. The study of impedance properties revealed the relaxation process, negative temperature coefficient of resistance behavior, grain and grain boundary formation, and the space charge effect in the high-frequency region of the material. The AC conductivity study explained the activation of charge carriers and the associated hopping mechanisms. A smaller activation energy (Ea) is observed at the low temperatures than in the high-temperature range. The ferroelectric property is confirmed through the P ∼ E hysteresis loop of the material at room temperature.

Effect of sintering temperature on dielectric and electrical properties of bio-waste derived beta-dicalcium silicate

Beta-dicalcium silicate ceramics were synthesized by mechanochemical-assisted solid-state reaction route using rice husks and chicken eggshells as silica and calcium oxide sources. The ceramics were sintered at 900, 1000, and 1100 °C for 2 h in air. The effect of sintering temperature on these ceramics' morphological, breakdown strength, dielectric, and electrical properties was investigated. It was found that the ceramic sintered at the optimized temperature of 1100 °C formed the pure β-dicalcium silicate (β-Ca2SiO4). Scanning electron micrographs showed that with the increase in sintering temperature, the average grain size and pore size of the sintered ceramics increased while the grain boundary density decreased, which promoted the breakdown path and resulted in a decrease in breakdown strength. The dielectric behavior examined from 25 to 300 °C and in a frequency range of 4–5 MHz found that the dielectric constant and loss tangent decreased with increasing frequency. Nyquist plot of impedance confirmed a non-Debye type relaxation, and grain and grain boundary contributions were revealed from equivalent circuit fitting. Variations of impedance spectroscopy reflect the positive and negative temperature coefficient of resistance behavior for these ceramics. Electric modulus spectra revealed that with the sintering temperature increase, the samples' conductivity activation energies increased from 0.35 to 0.46 eV. All the sintered samples attained low dielectric loss (0.004 < tanδ < 0.1) above 103 Hz, which makes them suitable materials for capacitor application.

High-Temperature Dielectric Relaxation and Electric Conduction Mechanisms in a LaCoO3-Modified Na0.5Bi0.5TiO3 System.

This research study examines the high-temperature dielectric relaxation and electric conduction mechanisms in (x)LaCoO3-(1 - x)Na0.5Bi0.5TiO3 samples, where x is 0.05, 0.10, and 0.15. The findings demonstrate that all the samples exhibit two dielectric transitions: first, a frequency-dispersive shoulder at a lower temperature (Ts) around 425-450 K, which is associated with polar nanoregions (PNRs), and second, from ferroelectric to paraelectric transition at the Curie temperature (Tc) approximately between 580 and 650 K. The impedance analysis reveals the negative temperature coefficient of resistance behavior of the specimens. The broad and asymmetric relaxation peaks obtained from modulus spectroscopy demonstrate a wide range of relaxations, suggesting non-Debye-type behavior. Furthermore, the conductivity studies provide insights into understanding the transport phenomena in the samples. The oxygen vacancies resulting from the addition of LaCoO3 into the Na0.5Bi0.5TiO3 ceramics are responsible for the relaxation and conduction processes, and the charge carrier is doubly ionized oxygen ion vacancies. All samples except for LCNBT10 at 1 kHz exhibit a negative magnetodielectric response.

Synthesis and analysis of structural, dielectric, and thermistor behaviour of zinc ferrite

This paper discusses the synthesis, dielectric properties, and applications of ZnFe2O4 for the thermistor. A high-temperature solid-state reaction method is used to create the polycrystalline ZnFe2O4 sample. The X-ray diffraction study identified the single spinel Cubic phase formation at room temperature without any impurities. The broadening of the XRD peaks determined structural parameters including crystallite size, microstrain, dislocation density, and percentage crystallinity which confirms the lower number of lattice defects in the ferrite. The dielectric properties of the sample are investigated as a function of temperature over selected frequencies. The high dielectric constant and low dielectric loss of the material suggest that it can be used in advanced energy storage systems. The minimal activation energies in the high-temperature region determined from the slope of the linear fit of the temperature-dependent curve indicate the enhancement of electrical conductivity. Looking into the strong dependence of resistivity on temperature, the thermistor parameters are evaluated using the resistance at different temperatures, which suggests its possible application for a thermistor as well as a temperature sensor. The calculation of different thermistor parameters such as thermistor constant, sensitivity factor, and activation energy confirms a negative temperature coefficient of resistance behavior of the ferrites at different temperatures and frequencies.

Effect of Ce Doping on the Structural, Dielectric, Ferroelectric, and Optical Characteristics of Bi3LaTi3O12 Ceramic

Herein, cerium‐modified bismuth lanthanum titanate (Bi3LaTi3−xCexO12) with composition x = 0, 0.1, 0.2, and 0.3, prepared using solid‐state reaction route is reported. The initial phase from room temperature X‐ray diffraction and Rietveld refinement analysis confirms the orthorhombic symmetry of the compound. Scanning electron micrograph shows an increase in grain size of the compounds from 0.61 to 0.80 μm with cerium doping. Temperature‐dependent dielectric study reveals diffused type of phase transition (DPT) around 257 °C for Bi3LaTi3O12. DPT becomes more evident with cerium substitution, and is distinctly observed for Bi3LaTi2.8Ce0.2O12. Complex impedance spectroscopic analysis indicates negative temperature coefficient of resistance behavior and non‐Debye type of relaxation in the compound. The room temperature P–E hysteresis loop confirms the ferroelectric property in the studied compounds. Moreover, with cerium substitution, energy storage efficiency increases from 62.7% to 77.1%. UV–visible spectroscopic analysis of the compounds shows reduction in the energy bandgap from 3.02 to 2.87 eV (for direct transition) and from 2.88 to 1.37 eV (for indirect transition) with incorporation of cerium at Ti site. Consequently, high energy storage density and low optical bandgap energy observed indicate the material's amenity for energy harvesting and optoelectronic device applications.

STUDY OF STRUCTURAL AND TRANSPORT PROPERTIES OF CuFe2O4 SYNTHESISED VIA LOW COST SOLID STATE REACTION ROUTE

ABSTRACT The ceramic compound CuFe2O4 was synthesised via conventional high-temperature solid-state reaction route. The structural study of the compound was done using X-ray diffraction technique. The preliminary structural study was performed using POWD software and a tetragonal structure was suggested. The Rietveld refinement of XRD (X-ray Diffraction) data was carried out using FullProf software and the refined lattice parameters were obtained as a = 5.80030 Å and c = 8.69400 Å with high tetragonality ratio. The crystallite size and lattice strain were calculated using Williamson–Hall (W-H) plot. The temperature and frequency dependent electrical properties of this compound are analysed using complex impedance technique. The impedance and modulus study of the compound showed the contribution of intra-grain effect to the overall electrical response. The studied ceramic possessed a non-Debye-type relaxation mechanism. The bulk resistance decreased with the increase in temperature, thus showing negative temperature coefficient of resistance behaviour. Modulus and conductivity study showed the evidence of conduction via hopping mechanism inside the material. Frequency-dependent AC conductivity followed Jonscher’s universal power law. The Arrhenius equation was fitted with the temperature-dependent AC conductivity at different frequencies, and activation energies were determined to understand the charge species involved in the conduction mechanism.

Complex impedance, dielectric constant, electric modulus, and conductivity analysis of Cd doped ZnO nanostructures at high temperatures

Cd-doped zinc oxide (ZnO) nanostructures with a standard formulation Z n ( 1 − x ) C d x O (x = 0%, 3%, 6%, and 10%) were fabricated by a co-precipitation technique. The structural and morphological analyses were studied using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The Study of x-ray diffraction investigation indorses the existence of a wurtzite structure with a P 6 3 mc space group in all the samples. Impedance spectroscopy, dielectric measurements, and electrical conductivity at different temperatures of 300–460 K with a frequency range from 20 Hz to 2 MHz were performed using an impedance LCR meter. The complex impedance spectrum ( Z ´ ´ v s Z ´ ) for all samples were fitted with a parallel bulk resistance ( R b ) and capacitance ( C b ) combination circuit. The results of the dielectric measurements indicate that the parameters ε ´ , ε ´ ´ , and tanδ are reduced with the increasing frequency and increase with temperature. The complex electric modulus plots ( M ´ , M ´ ´ ) with frequency have explained the non-Debye type of relaxations mechanism due to interfacial and depolarization. The variation of ac ( σ a c ) conductivity with Cd concentration indicates a gradual increase because the impedance values with Cd-doped decrease. It is confirmed that the activation energies decrease with the doping of Cd concentration. Moreover, ac conductivity was then investigated by Jonscher's power law. Finally, the temperature-dependent exponent s fitted well with the correlated barrier hopping (CHB) conduction. • Cd-doped ZnO nanoparticles with different concentrations were fabricated by the co-precipitation method. • XRD studies revealed the incorporation of Cd into ZnO lattice. • Nyquist plots suggested the negative temperature coefficient of resistance behaviour. • The influence of Cd-doping on the electrical behaviour of ZnO was reported.

Structural characteristics, impedance spectroscopy, ac-conductivity and dielectric loss studies on RF-magnetron sputtered F doped ZnO (FZO) thin films

The manuscript demonstrates the structural characteristics, impedance spectroscopy, ac-conductivity and dielectric loss studies on F-doped ZnO films grown by RF-magnetron sputtering at TS ∼50 and 125 °C. The electrical impedance spectroscopy enables separately recognizing the contributions of grain and grain-boundary on the electronic properties. The relaxation time distribution on temperature results in the asymmetric and depressed nature of the semi-circular arcs in the Cole-Cole plot and endorses a non-Debye type response under changing electric fields. The negative temperature coefficient of resistance behaviour indicates the semiconducting characteristics. A parallel equivalent circuit model (R || CPE) is designed to fit the semi-circular arc. The grain boundary being more resistive than ZnO-grain, its activation energy appears more significant because of the dynamic disorder characteristics. The ac-conductivity obeys Jonscher power law, and frequency exponent n < 1 suggests hopping of charge carriers with translation motion under ac electric field. The temperature-dependent dc-conductivity follows the Arrhenius behaviour. Sample deposited at higher TS has a greater carrier lifetime due to the improved crystalline structure and lesser defects. Although, the dielectric loss in the form of conduction loss is higher for the low temperature grown sample owing to the relatively effortless movement of charge carriers and formation of dipoles due to its elevated dc conductivity consequent to increased doping.

Dielectric properties of alumino-silicate ceramics synthesized by plasma sintering

The polycrystalline ceramic specimens of three different alumino-silicate solid solutions (Al0.70Si0.30O, Al0.73Si0.27O and Al0.75Si0.25O) consisting of different alumina and silica concentrations have been synthesized by thermal plasma sintering technique. From structural analysis carried out by X-ray diffraction, the ceramics are mostly found to consist of two different phases of mullite and sillimanite. SEM images of these ceramics reveal a high dense and less porous microstructure with homogeneous distribution of grains throughout their surface. These materials exhibit high dielectric constant value (>103) with low dissipation factor. The AC conductivity analysis reveals that Al0.70Si0.30O and Al0.75Si0.25O ceramics possess room temperature conductivity values of the order of 10−5, whereas Al0.73Si0.27O has conductivity of 10−7 order that increases with rise in temperature. From the Nyquist plots, the grain and grain boundary conductivities are distinguished and negative temperature coefficient of resistance behavior is identified in these ceramics with small positive temperature coefficient of resistance effect.

Optical induction in K0.5Na0.5NbO3 ferroelectric ceramic at low calcination temperature by sol-gel route

K0.5Na0.5NbO3 ceramic was synthesized at low calcination temperature by sol-gel route. Structural properties of ceramic were investigated by X-ray diffractometer, FESEM and FTIR spectrometer. Electro-optical properties of ceramic were investigated by UV-Vis and PL spectrometer. Dielectric nature of ceramic was studied at different frequencies and temperatures which disclosed that ceramic has maximum dielectric permittivity at 500 KHz. AC conductivity analysis shows negative temperature coefficient of resistance behavior. Leakage current was studied up to 180 V which shows low value of leakage current at room temperature. Ferroelectric nature was analyzed at different electric fields (5–20 kVcm−1) at 50 Hz.

Dielectric behaviour of mechano-chemically synthesised [(CH3NH3)3Bi2Br9]: a lead free hybrid perovskite

ABSTRACT Lead-free hybrid halide perovskite (CH3NH3)3Bi2Br9 has been successfully synthesised by mechano-chemical method. The microstructure analysis by Rietveld’s refinement method revealed that the crystal belongs to trigonal system with space group P m1. The obtained microstructural parameters are well in agreement with the previously published data. Temperature-dependent AC conductivity, impedance spectroscopy and complex dielectric properties have been investigated in detail. The negative temperature coefficient of resistance behaviour reveals the semiconducting nature of the materials. The complex impedance spectroscopy also supports the semiconducting nature of the sample with activation energy for conduction ~0.38 eV.

Structural, electrical, and dielectric properties of chemically derived Sm-Doped cubic lanthanum molybdate nanomaterials

In this study, we successfully synthesized single-phase cubic fluorite structure La6-xSmxMoO12 (x = 0.4, 0.6. 0.8, 1) materials using the solution combustion method and determined their structural and electrical properties. Rietveld refinement of the X-ray diffraction patterns provided detailed microstructural information for the prepared compositions. Field emission-scanning electron microscopy verified the uniform nature of the particles in all samples. The optical band gap obtained from the ultraviolet–visible spectra indicated a red shift up to a dopant concentration of x = 0.8 and a blue shift subsequently. Fourier transform-infrared spectroscopy confirmed the presence of different structural bonds in the compounds. The impedance spectra demonstrated the thermally activated non-Debye type nature of the compounds, and the electrical conductivity demonstrated their negative temperature coefficient of resistance behavior. The time–temperature superposition principle was verified based on the scaling of the impedance spectra. The dielectric constant was found to increase with the temperature and the dopant concentration.

Investigation on diffuse phase transition through Raman and dielectric properties of Pb(Fe0.5Nb0.5)O3 – Pb(Co0.33Nb0.67)O3 solid solutions

We report a series of Pb based multiferroic solid solutions (1-x) Pb(Fe0.5Nb0.5)O3 – (x) Pb(Co0.33Nb0.67)O3 (0.1 ≤ x ≤ 0.5) (shortened as PFCN), synthesized using a single-step solid-state reaction method. The structural, microstructural, Raman, and temperature (301–481 K) dependent dielectric (102–106 Hz) and conductivity properties were thoroughly investigated. The room temperature X-ray diffraction data reveals the monoclinic phase with the Cm space group for all the solid solutions. The atomic-level structural parameters were obtained for all the solid solutions from the Rietveld refinement technique, and it was observed that an increase in the unit cell volume with an increase of PCN content in PFN. The field emission scanning electron microscope images confirm the densely packed, uniform coarse arrangement in all the samples. In x = 0.4 and 0.5, a small amount of porous structure was noticed, indicates the reduction in the densities. Energy-dispersive X-ray spectroscopy reveals the existence of Pb, Fe, Co, Nb, and O elements according to stoichiometry. The temperature-dependent Raman spectra of all the solid solutions show a decrease in the intensity and changes in the spectral line shape of B-localized F1u (~250 cm−1) and BO6 octahedral rotation F1g (~260 cm−1) modes around the characteristic temperature, may be a structural transformation from monoclinic to cubic above Tm. The frequency-dependent ε′ and tanδ reveal the presence of Maxwell-Wagner polarization in the lower frequency. The temperature-dependent ε′ shows the ferroelectric relaxor type diffused phase transition Tm (TC) around ~360 K, ~340 K, ~330 K & ~320 K for x = 0.1, 0.2, 0.3 and 0.4, respectively. The reported Tm (TC) systematically decreases with increasing x due to the lower Tm (TC) of PCN compared to PFN. These results were consistent with the anomalies observed at the vicinity of Tm in the Raman spectra. The frequency-dependent ac-conductivity studies reveal the negative temperature coefficient of resistance behavior and obey Johnscher's power law. For x = 0.1 to 0.4, the hump-like behavior was found in both temperature-dependent tanδ and ac conductivity around the transition temperature related to the reorientation of domains, domain wall motion, dipolar contribution to the ferroelectric materials.

Evaluation of Structural and Electrical Properties of Ball-milled NaNbO3 Ceramic

This work reports the effect of milling on the structural, microstructural, electrical, and piezoelectric properties of NaNbO₃ (NN) ceramics synthesized using a solid-state reaction method. X-ray diffraction studies exhibited that the lattice structure of milled and un-milled NN samples is orthorhombic with a space group <em>Pmc</em>21. The average particle size and lattice strain were found to 203 nm and 0.05 un-milled samples whereas they were 37 nm and 0.2 for 10 h milled samples. FTIR spectra indicated a shift in peak position with milling time. SEM image showed the formation of small grains ~1.2 µm for 10 h milled NN samples which is advantageous for dielectric applications in high density integrated circuits. An increase in the values of dielectric constant from 377 to 698, <em>d33</em> from 29 to 37, and a drop in critical temperature from 426°C to 352°C at 1 kHz were registered for un-milled and milled samples. A negative temperature coefficient of resistance behaviour was noticed from the impedance and ac conductivity analyses. The correlated barrier hopping model successfully explains the charge transport mechanism in the present ceramic system and ac conductivity data obeyed Jonscher’s universal power law. A marked increment in <em>d33</em> with smaller particle size was observed with the increasing milling hour that could make NN a promising lead-free piezoelectric material for piezo-sensing/detection and energy harvesting applications.