Electrical conductivity relaxation in PVOH-LiClO4-Al2O3

We report on electrical conductivity relaxation measurements of solid polymer electrolytes (SPE) based on poly(vinyl alcohol) (PVOH) and LiClO₄ in which nanoporous Al₂O₃ particles with average pore diameter of 58 Å were dispersed. A power law frequency dependence of the real part of the electrical conductivity is observed as a function of temperature and composition. This behaviour is typical of systems in which correlated ionic motions in the SPE bulk material are responsible for ionic conductivity. This variation is well fitted to a Jonscher expression σ′(ω) = σ₀[1 + (ω/ω₀)^p] where σ₀ is the dc conductivity, ω₀ the characteristic angular frequency relaxation and p is the fractional exponent between 0 and 1. For a prototype membrane with composition 0.9PVOH − 0.1LiClO₄ + 7 wt.%Al₂O₃, it was found that the temperature dependence of σ₀ and ω₀, may be described by the VTF relationship, ? = ?₀ exp[−B/(T − T₀)], with approximately the same constant B and reference temperature T₀, indicating that ion mobility is coupled to the motions of the polymer chains. Moreover, p decreased with increasing temperature, from 0.68 at T = 319 K, to 0.4 at T = 437 K, indicating weaker correlation effects among mobile ions when the temperature is increased.     

Low temperature sintering and microwave dielectric properties of Ce2(WO4)3 ceramics

Ce₂(WO₄)₃ ceramics have been synthesized by the conventional solid-state ceramic route. Ce₂(WO₄)₃ ceramics sintered at 1000 °C exhibited ?_r = 12.4, Qxf = 10,500 GHz (at 4.8 GHz) and τ_f = −39 ppm/°C. The effects of B₂O₃, ZnO–B₂O₃, BaO–B₂O₃–SiO₂, ZnO–B₂O₃–SiO₂ and PbO–B₂O₃–SiO₂ glasses on the sintering temperature and microwave dielectric properties of Ce₂(WO₄)₃ were investigated. The Ce₂(WO₄)₃ + 0.2 wt% ZBS sintered at 900 °C/4 h has ?_r = 13.7, Qxf = 20,200 GHz and τ_f = −25 ppm/°C.     

More studies on the PVOH-LiH2PO4 polymer system

Polymer electrolytes based on poly(vinyl alcohol) (PVOH) and lithium dihydrogen-phosphate (LiH₂PO₄) with molar ratio of x = 0.07, 0.10 and 0.14 were prepared in order to investigate the mechanism of ionic motion. Admittance spectroscopy measurements were used to study electrical conductivity relaxation on both anhydrous and hydrated samples in the 5 Hz to 13 MHz frequency range and temperatures ranging from 25 to 150 °C. The conductance, G, shows dispersion above a crossover frequency, f_p. This behavior is typical of systems in which correlated ionic motions in the bulk material are responsible for ionic conductivity. For hydrated samples, results reveal that the temperature dependence of the dc-conductivity, σ₀ and the characteristic frequency, f_p, shows Arrhenius-type behavior with the same energy, E_σ. However, for anhydrous conductivity, a Vogel-Tamman-Fulcher (VTF) behavior is shown for both σ₀(T) and f_p(T), with the same pseudo activation energy, B and B_σ, respectively, thus indicating that they are correlated with chain mobility.     

Physical properties of new,lead free (Na0.5Bi0.5)(1−x)BaxTi(1−x)(Fe0.5Nb0.5)xO3 ceramics

This study reports on the synthesis of polycrystalline samples of (Na_0.5Bi_0.5)_(1−x)Ba_xTi_(1−x)(Fe_0.5Nb_0.5)_xO₃ with x=0, 0.025, 0.05, 0.075, and 0.1, using the solid-state reaction technique. It investigates the effects of the substitution of sodium and bismuth by barium in the A site and of titanium by iron and niobium in the B site with regard to the free NBT symmetry and dielectric properties were investigated. The crystallographic and dielectric properties were also investigated. The diffractograms showed that all the samples had a single phase character. The increase of ceramic lattice parameters induced an increase in the size of the perovskite lattice. This increase was caused by the increase of the radii of the A and B sites. Room temperature X-ray data revealed that the ceramic structures underwent a gradual distortion with the increase in the composition fraction. Dielectric permittivity was measured in the temperature range of 120–780 K with frequencies ranging from 1 to 10³ KHz. Three anomalies, namely T_d, T₁ and T_m, were detected and noted to coexist at lower T_d and T_m as the rate of substitutions increased. All the samples exhibited a diffuse phase transition and implied better dielectric permittivity maxima values at temperatures approaching room temperature, since the substitution rate values increased more than that of pure NBT. A relaxor behavior with ΔT_m=14 K and ε'_rmax=3876 at 1 kHz was observed for (Na_0.5Bi_0.5)_0.9Ba_0.1Ti_0.9(Fe_0.5Nb_0.5)_0.1O₃ ceramic.     

Dielectric properties of Bi-doped Ba0.8Sr0.2TiO3 ceramic solid solutions

Bismuth-doped barium–strontium–titanate ceramics of the formula (Ba_0.8Sr_0.2)_(1−1.5y)Bi_yTiO₃ were prepared using a conventional solid-state reaction method. The structure, dielectric properties, and ferroelectric relaxor behaviour of all compositions were thoroughly investigated. The findings revealed a broad dielectric anomaly and a shift in dielectric maxima towards higher temperatures with increasing frequency. The diffuseness degree indicator γ was about 1.68, and dielectric relaxation was noted to follow the Vogel–Fulcher relationship, with T_f=185 K, f₀=1.18×10¹⁰ Hz, and Ea=0.35 eV, which further supported the spin-glass-like properties of BBSTs. The latter were also noted to display significant ferroelectric relaxor behaviour that could be attributed to the presence of Bi³⁺ doping ions. The degree of relaxation behaviour was noted to increase with the increase in bismuth concentration. Raman spectra were investigated as a function of temperature, and the findings confirmed the results from X-ray and dielectric measurements. Among the compositions assayed in this solid solution, 10% Bi-doped Ba_0.8Sr_0.2TiO₃ yielded promising relaxor properties that make it a strong candidate for future industrial application in the production of efficient and eco-friendly relaxor ferroelectric materials.     

Synthesis and characterization of A2 + B3-type hyperbranched aromatic polyesters with phenolic end groups

Hyperbranched (hb) aromatic polyesters with phenolic end groups were synthesized according to the A₂ + B₃ approach both, by solution polymerization and by melt (bulk) polymerization with different monomer ratios (A₂:B₃). The hb polyesters produced from solution polymerization exhibited higher yields, molar masses and glass transition temperature (T_g) compared to the products prepared in the melt. The resulting hb aromatic polyesters from the A₂ + B₃ approach were also compared with their properties to hb aromatic polymers produced from the well known AB₂ monomer 3,5-bis(trimethylsiloxy)benzoyl chloride. Both types of hb aromatic polyesters possess high T_g, high thermal stability and good solubility in common organic solvents. A typical melt viscosity behavior with shear thinning effect was also observed for both. Thus similar polymer properties compared to melt-condensed products were obtained with the A₂ + B₃ approach by solution polycondensation possessing the advantage of easy monomer availability and much milder polymerization conditions (at room temperature in solution) compared to the AB₂ approach.     

The nucleation and crystallization of MgO-B2O3-SiO2 glass

The nucleation and crystallization of MgO-B₂O₃-SiO₂ (MBS) glass were studied by means of a non-isothermal, thermal analysis technique, X-ray diffraction and scanning electron microscopy. The temperature range of the nucleation and the temperature of the maximum nucleation rate for MBS glass were determined from the dependences of the inverse temperature at the DSC peak (1/T_p) and the maximum intensity of the exothermic DSC crystallization peak ((δT)_p) on the nucleation temperature (T_n). For MBS glass the nucleation occurred at 600-750 °C, with the maximum nucleation rate at 700 °C, whereas the nucleation and crystal growth processes overlapped at 700 °C < T ≤ 750 °C. The analyses of the non-isothermal data for the bulk MBS glass using the most common models (Ozawa, Kissinger, modified Kissinger, Ozawa-Chen, etc.) revealed that the crystallization of Mg₂B₂O₅ was three-dimensional bulk with a diffusion-controlled crystal growth rate, that n = m = 1.5 and that the activation energy for the crystallization was 410-440 kJ/mol.     

High electromechanical strain properties by the existence of nonergodicity in LiNbO3–modified Bi1/2Na1/2TiO3–SrTiO3 relaxor ceramics

This study investigated the effect of LiNbO₃ modification on the dielectric, ferroelectric and electromechanical strain properties of Bi_1/2Na_1/2TiO₃–SrTiO₃ (BNT–ST) lead–free relaxor ceramics. The sintering temperature for lead–free BNT–ST relaxor ceramics was slightly decreased from 1175?°C to 1050?°C by modifying with LiNbO₃. We found that the sintering temperature affects the dielectric behavior of 0.76BNT–(0.24?x)ST–xLiNbO₃ (BNST–100xLN) ceramics at high temperature (near dielectric maximum temperature, T_m). The T_m for the low–temperature sintered sample was shifted to relatively higher temperature by comparison with the high–temperature sintered samples. Furthermore, the degradation of dielectric behavior near T_m in low–temperature sintered BNST–2LN ceramics was revealed after poling treatment and seem to be related to the existence of a high temperature stabilized nonergodic relaxor phase. Accordingly, we assume that the stabilized nonergodic relaxor phase is responsible for the relatively late transition from ferroelectrics to the relaxor. Therefore, we obtained the improved d₃₃^* of 616?pm/V as the highest value in low–temperature sintered BNST–2LN ceramics.     

Preparation and microwave dielectric properties of 3ZnO·B2O3 ceramics with low sintering temperature

The preparation and dielectric properties of 3ZnO·B₂O₃ ceramics were investigated. Dense 3ZnO·B₂O₃ ceramics were obtained as sintered in the temperature range from 950 to 1000 °C for 3 h. The X-ray diffraction showed that the obtained ceramics were of a monoclinic 3ZnO·B₂O₃ structure. The ceramic specimens fired at 955 °C for 1 h exhibited excellent microwave dielectric properties: ?_r ∼ 6.9, Q × f ∼ 20,647 GHz (@6.35 GHz), and τ_f ∼ −80 ppm/°C. The dependences of relative density, ?_r, and Q × f of ceramics sintered at 955 °C on sintering soaking time showed that they all reached their plateaus as the soaking time was up to 60 min. Meanwhile, 3ZnO·B₂O₃ ceramics had no reaction with silver during cofiring, indicating it is a potential candidate for low-temperature cofired ceramic (LTCC) substrate.     

Free volume in poly(n-alkyl methacrylate)s from positron lifetime and PVT experiments and its relation to the structural relaxation

Free volume data from positron annihilation lifetime spectroscopy (PALS) experiments are combined with a Simha-Somcynsky (S-S) equation of state analysis of pressure-volume-temperature (PVT) data to model free volume contributions to structural mobility in a series of poly(n-alkyl methacrylate)s. From the PALS data the glass transition temperature, T_g, decreases (from 382 to 224 ± 5 K) and a given mean free volume is observed at lower temperatures as the side-chain length increases (going from methyl- to hexyl-). This is evidence of an internal plasticization whereby the side-chains reduce effective packing of molecules. By comparing PALS and PVT data, the hole number per mass unit, N_h′, is calculated using different methods; this varies between 0.54 and 0.86 × 10²¹ g⁻¹. It is found that the extrapolated free volume becomes zero at a temperature T₀′ that is smaller than the Vogel temperature T₀ of the α-relaxation. The α-relaxation frequencies can be fitted by the free volume theory of Cohen and Turnbull, but only when the free volume V_f is replaced by (V_f − ΔV) where ΔV( = E_f(T₀ − T₀′), E_f is the thermal expansivity of V_f) varies between 0.060 and 0.027 ± 0.003 cm³/g, decreasing with side-chain length, apart from poly(n-hexyl methacrylate) where ΔV increases to 0.043 ± 0.003 cm³/g. One possible interpretation of this is that the α-relaxation only occurs when, due to statistical reasons, a group of m or more unoccupied S-S cells are located adjacent to one another. m is found to vary between 8 and 2 for poly(methyl methacrylate) and poly(n-butyl methacrylate), respectively. We found that no specific feature in the free volume expansion was consistently in coincidence with the dynamic crossover.     

Effect of Bi2O3 additives on sintering and microwave dielectric behavior of La(Mg0.5Ti0.5)O3 ceramics

Bi₂O₃ was selected as liquid phase sintering aid to lower the sintering temperature of La(Mg_0.5Ti_0.5)O₃ ceramics. The sintering temperature of La(Mg_0.5Ti_0.5)O₃ ceramics is generally high, about 1600 °C. However, the sintering temperature was significantly lowered about 275 °C from 1600 °C to 1325 °C by incorporating in 15 mol% Bi₂O₃ and revealed the optimum microwave dielectric properties of dielectric constant (?_r) value of 40.1, a quality factor (Q × f) value of 60,231 GHz, and the temperature coefficient (τ_f) value of 70.1 ppm/°C. During all addition ranges, the relative dielectric constants (?_r) were different and ranged from 32.0 to 41.9, the quality factors (Q × f) were distributed in the range of 928–60,231 GHz, and the temperature coefficient (τ_f) varies from 0.3 ppm/°C to 70.3 ppm/°C. Noticeably, a nearly zero τ_f can be found for doping 5 mol% Bi₂O₃ sintering at 1325 °C. It implies that nearly zero τ_f can be achieved by appropriately adjusting the amount of Bi₂O₃ additions and sintering temperature for La(Mg_0.5Ti_0.5)O₃ ceramics.     

Evolution of Relaxor Behavior in Multiferroic Pb(Fe2/3W1/3)O3-BiFeO3 Solid Solution of Complex Perovskite Structure

Mutiferroic materials like bismuth ferrite BiFeO₃ have attracted much interest in the last decade due to their promising potential for such applications as spintronics and magnetoelectric data storage devices. On the other hand, relaxor ferroelectrics have been intensively studied for their complex structures with quenched disorder and polar nanoregions which play an important role in their outstanding piezoelectric performance. Much less studied are the single-phase multiferroics that exhibit ferroelectric and/or magnetic relaxor behavior and the correlation between their structure and intricate magneto-electric interactions. In this work, we investigate the evolution of the structure and relaxor behavior in the solid solution between the complex perovskite multirelaxor Pb(Fe_2/3W_1/3)O₃ [PFW] and canonical multiferroic BiFeO₃ [BFO], (1-x)PFW-xBFO (with a solubility limit of x = 0.30). The temperature dependences of the dielectric permittivity and loss tangent measured in the frequency range from 100 Hz to 1 MHz indicate characteristic relaxor ferroelectric properties for compositions of x ≤ 0.15, with a frequency-dependent dielectric permittivity peak and its temperature, T_m, satisfying the Vogel-Fulcher law. Detailed studies of the evolution of the relaxor behavior with composition reveal that T_m decreases firstly with a small amount (x = 0.05) of BFO substitution and then increases with further increase of BFO concentration. The degree of relaxor character, as defined by ΔT_m [T_m (1 MHz) - T_m (100 Hz)], increases monotonously with increasing BFO content, signifying an enhancement of relaxor behavior with BFO substitution, which is confirmed by the Lorenz-type quadratic variation of the static permittivity. A temperature - composition phase diagram is constructed in terms of the characteristic Burns temperature (T_B) and freezing temperature (T_f), which delimits a paraelectric state (PE) above T_B, a non-ergotic relaxor state (NR) below T_f, and an ergotic relaxor state (ER) in between. The observed enhancement of relaxor behavior is explained by an increase in the number and size distribution of polar nanoregions in the ER phase, resulting from increased compositional and charge disorders as a result of BFO substitution. The evolution of relaxor behavior and its microscopic mechanisms studied in this work are insightful for a better understanding the multirelaxor properties in multiferroics. Moreover, further substitution of BFO (x ≥ 0.2) flattens the permittivity curves and leads to a temperature-stable variation of high dielectric constant (≈ 10³) in a wide temperature range, making the PFW-BFO solid solution attractive for such applications as high energy density capacitors.     

Sintering of glass-added BaZn1/3Nb2/3O3 ceramics

The complex perovskite oxide Ba(Zn_1/3Nb_2/3)O₃ (BZN) has been studied for its attractive dielectric properties which place this material interesting for applications as multilayer ceramics capacitors or hyperfrequency resonators. This material is sinterable at low temperature with combined glass phase–lithium salt additions, and exhibits, at 1 MHz very low dielectric losses combined with relatively high dielectric constant and a good stability of this later versus temperature. The 2 wt.% of ZnO–SiO₂–B₂O₃ glass phase and 1 wt.% of LiF-added BZN sample sintered at 900 °C exhibits a relative density higher than 95% and attractive dielectric properties: a dielectric constant ?_r of 39, low dielectrics losses (tan(δ) < 10⁻³) and a temperature coefficient of permittivity τ_? of 45 ppm/°C⁻¹. The 2 wt.% ZnO–SiO₂–B₂O₃ glass phase and 1 wt.% of B₂O₃-added BZN sintered at 930 °C exhibits also attractive dielectric properties (?_r = 38, tan(δ) < 10⁻³) and it is more interesting in terms of temperature coefficient of the permittivity (τ_? = −5 ppm/°C). Their good dielectric properties and their compatibility with Ag electrodes, make these ceramics suitable for L.T.C.C applications.     

Microwave dielectric properties and structure of ZnO-Nb2O5-TiO2 ceramics

Ceramic samples based on ZnO-Nb₂O₅-TiO₂ compositions have been prepared using solid state ceramic route. The work was carried out over a wide range of initial ZnNb₂O₆ and Zn_0.17Nb_0.33Ti_0.5O₂ compounds concentration. The crystal structure and microstructure developments were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was shown that the phase compositions of the samples present itself a columbite type and mixture of two phases—solid solutions of columbite and rutile types.The sintering behavior, permittivity, its temperature coefficients and quality factor had been characterized for ceramic samples in depending on compositions. The permittivity of the samples in this system is within the limits from 24 to 80, τ_? from 150 to −560 ppm/°C. For the samples with τ_? ∼ 0, ?_r ∼ 43.8 and Q·f = 35000 GHz at f = 9 GHz. The comparatively low sintering temperature (≤1080 °C) and high dielectric properties in microwave range make these ceramics promising for application in electronics.     

Phase diagram and properties of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 polycrystalline ceramics

yPb(In_1/2Nb_1/2)O₃-(1 − x − y)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ (yPIN-(1 − x − y)PMN-xPT) polycrystalline ceramics with morphotropic phase boundary (MPB) compositions were synthesized using columbite precursor method. X-ray diffraction results indicated that the MPB of PIN-PMN-PT was located around PT = 0.33-0.36, confirmed by their respective dielectric, piezoelectric and electromechanical properties. The optimum properties were found for the MPB composition 0.36PIN-0.30PMN-0.34PT, with dielectric permittivity ?_r of 2970, piezoelectric coefficient d₃₃ of 450 pC/N, planar electromechanical coupling k_p of 49%, remanent polarization P_r of 31.6 μC/cm² and T_C of 245 °C. According to the results of dielectric and pyroelectric measurements, the Curie temperature T_C and rhombohedral to tetragonal phase transition temperature T_R-T were obtained, and the “flat” MPB for PIN-PMN-PT was achieved, indicating that the strongly curved MPB in PMN-PT system was improved by adding PIN component, offering the possibility to grow single crystals with high electromechanical properties and expanded temperature usage range (limited by T_R-T).     

Structural anomaly and electrical relaxation in (Na2/3Pb1/3)(Mn1/2Nb1/2)O3 ceramics

The X-ray diffraction patterns of (Na_2/3Pb_1/3)(Mn_1/2Nb_1/2)O₃ ceramics were measured within 15–850 K temperature range. The anomaly in the thermal expansion temperature dependence occurred in 250–365 K range. The generalised Cole–Cole model was proposed to describe the measured effective electric permittivity influenced by high electric conduction and the coexistence of two contributions ?*(T,f) = ?*_lattice + ?*_carriers was considered. The analysis of the electric permittivity and conduction exhibited two relaxation processes. The electric conduction relaxation characteristic time values indicated the small polaron mechanism with τ₀ ≈ 10⁻¹³ s occurring in 240–345 K range and the ionic mechanism with τ₀ ≈ 10⁻¹¹ s involved in the other relaxation occurring in the 320–510 K range. The ionic relaxation process was ascribed to a subsystem of defects, which was weakly interrelated to the anomaly in thermal expansion of the (Na_2/3Pb_1/3)(Mn_1/2Nb_1/2)O₃ ceramics. The Gate model was proposed to describe the ionic relaxation mechanism.     

Formation of high conductivity glasses in the system AgIAg2OB2O3

Glass phases showing high ionic conductivity at room temperature were prepared through a rapid quenching of the molten mixtures of the system AgIAg₂OB₂O₃ (a fixed Ag₂O/B₂O₃ = 1 molar ratio was always considered): the obtained specimens were homogeneous and transparent cylindrical blocks.Disk shaped cells prepared with such specimens did not show any grain-grain effect as supported by the comparison between four electrodes dc and ac conductivity determinations.A less than 10^?9(ohm cm)^?1 electronic conductivity was found.According to X-rays diffraction and DTA investigations, X_AgI > 0.8 samples contained crystallized AgI, whereas 0.1 < X_AgI < 0.8 samples could be considered actual vitreous homogeneous phases.AgI contents lower than 10 mole% were not considered due to the observed presence of segregated metallic silver.Room temperature density and conductivity data showed a regular behaviour vs X_AgI in the vitreous phases range, whereas an evident discontinuity was observed about X_AgI = 0.8.Linear fits in the Arrhenius plots of the bulk conductivity were obtained in the 120 K?T_g (glass transition temperature) range: the corresponding activation energies, as well as the high room temperature conductivities, allowed to closely compare these vetrous phases with the so called “superionic” conductors.     

Microwave dielectric properties of Ba3Ti4−x(Zn1/3Nb2/3)xNb4O21 for low temperature co-fired ceramics

The effects of substitution of (Zn_1/3Nb_2/3) for Ti on the sintering behavior and microwave dielectric properties of Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ (0 ≤ x ≤ 4) ceramics have been investigated. The dielectric constant (?_r) and the temperature coefficient of the resonant frequency (τ_f) of Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ ceramics decreased with increasing x. However, the Q × f values enhanced with the substitution of (Zn_1/3Nb_2/3) for Ti. It was found that a small amount of MnCO₃-CuO (MC) and ZnO-B₂O₃-SiO₂ (ZBS) glass additives to Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ (x = 2) ceramics lowered the sintering temperature from 1250 to 900 °C. And Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ (x = 2) ceramics with 1 wt% MC and 1 wt% ZBS sintered at 900 °C for 2 h showed excellent dielectric properties: ?_r = 53, Q × f = 14,600 GHz, τ_f = 6 ppm/°C. Moreover, it has a chemical compatibility with silver, which made it as a promising material for low temperature co-fired ceramics technology application.     

Low temperature and microwave dielectric properties of TiO2/ZBS glass composites

TiO₂ based ceramic/glass composites were prepared by a non-reactive liquid phase sintering (NLPS) using zinc borosilicate (ZBS) glass having the deformation temperature of 588 °C. The compounds of Zn₂SiO₄ and Zn₄B₆O₁₃ were formed after the sintering process, indicating that the ZBS glass was a non-reactive one in this system. For TiO₂/50 vol% ZBS glass composite, the two-stage sintering behavior was conducted as the sintering temperature increased. The former might be correlated to the NLPS process and the latter appeared to be related to the crystallization. The dielectric constant (?_r) was mainly affected by the porosity and obeyed the logarithmic mixing rule. The quality factor (Q × f₀) showed an increase and then a steep decrease after the maximum at 850 °C. TiO₂/50 vol% ZBS glass composite sintered at 900 °C demonstrated 36 in the dielectric constant (?_r) and 7500 GHz in the quality factor (Q × f₀) for an application to LTCC filters.     

Structural and electrical properties of four-layers Aurivillius phase BaBi3.5Nd0.5Ti4O15 ceramics

A new compound of barium bismuth neodymium titanate BaBi_3.5Nd_0.5Ti₄O₁₅ was synthesized using the traditional solid-state reaction method. X-ray diffraction analysis confirmed the compound to be a layered tetragonal structure and Raman spectrum indicated that Nd ions occupy the A site. The plate-like morphology with average grain size about 2–4 μm was observed by a scanning electron microscope (SEM). A precision impedance analyzer was used to measure the dielectric properties and impedance spectroscopy of the ceramics. The results show that the temperature of dielectric constant maximum (T_m), the room temperature dielectric constant (ε_r) and loss (tan δ) at 100 kHz are 287° C, 326 and 0.017, respectively. The modified Curie–Weiss law was used to describe the relaxor behavior of the ceramics which was attributed to the A site cationic disorder. The remnant polarization (2P_r) of the sample was observed to be 1.27 μC/cm² at room temperature.