Journal of Electroceramics最新文献

Multiferroic ceramics (1-x)BaTiO₃-xNi_0.7Zn_0.3Fe₂O₄ exhibit strong correlations between structural distortion, vibrational dynamics, and magnetic behavior. X-ray diffraction, Raman, and FTIR analyses reveal a slight contraction of the BaTiO₃ lattice and a blue shift in the Ti–O stretching mode, indicating increased bond energy due to spinel phase incorporation. Zn²⁺ substitution in the ferrite phase optimizes cation distribution, enhancing Fe³⁺–Fe³⁺ superexchange interactions and increasing saturation magnetization from 0.182 emu/g (x = 0) to 12.84 emu/g (x = 0.3) while reducing coercivity from 0.25 kOe to 0.082 kOe. Maximum polarization peaks at 57.08 µC/cm² for x = 0.2, attributed to strong internal fields and efficient domain switching. These results demonstrate tunable ferroelectric and magnetic responses in BTO–NZFO composites, highlighting their potential for magnetoelectric sensors and multifunctional electronic devices.

Graphical Abstract

Barium strontium titanate (Ba_0.6Sr_0.4TiO₃, BST) is a material with excellent dielectric properties in the ferroelectric material system. Bismuth magnesium niobate (Bi_1.5MgNb_1.5O₇, BMN) is a non-ferroelectric material. It was doped into BST, and four groups of samples BST-xBMN(x = 0-0.3) were prepared to discuss the influence of BMN on BST. BMN exists in an amorphous state between BST grains. Therefore, BST-xBMN still has a perovskite structure. Excessive doping is observed to cause pore formation within the BST. The doping of BMN reduces the dielectric constant of BST from 4500 to 1500 (at room temperature). However, it also reduces the dielectric loss of BST from 0.02 to 0.005. BMN improves the performance stability of BST. The dielectric properties of BST-xBMN are more stable than those of BST with the change of temperature or frequency.

The development of high-performance solid-state ionic conductors requires structurally stable and lithium-rich oxide materials with efficient Li⁺ transport characteristics. In this context, the present study aims to synthesize and evaluate the structural, microstructural, and relaxation properties of nanocrystalline Li₂NiZrO₄ for potential solid-state electroceramic applications. Lithium-rich Li₂NiZrO₄ was prepared via a glycine-assisted solution combustion route using a stoichiometric (1:1) oxidizer–fuel ratio, enabling the formation of a phase-pure nanocrystalline compound. Structural analysis using X-ray diffraction confirmed a single-phase cubic lattice with an average crystallite size of ~ 51 nm, while TG–DTA verified its thermal stability. SEM imaging revealed a uniform surface morphology, and EDS confirmed the expected elemental composition. TEM and HRTEM further validated the nanocrystalline nature, showing monodisperse domains with an average size of 47.9 ± 0.02 nm. Impedance spectroscopy was employed to probe relaxation dynamics over a wide temperature range. The frequency-dependent electric modulus, M″(ω), exhibited well-defined relaxation peaks, and the corresponding relaxation time (τ = 1/ωₚ) followed Arrhenius behaviour with an activation energy of 0.39 ± 0.02 eV, indicating facile Li⁺ ion migration or dipolar reorientation. The temperature-invariant scaling of modulus spectra suggests a common relaxation mechanism governing charge transport. Overall, the study demonstrates that nanocrystalline Li₂NiZrO₄ possesses favourable structural stability, nanoscale coherence, and low activation energy for ionic motion. These attributes underline its promise as a solid-state ionic conductor suitable for advanced energy storage and electroceramic applications.

This study explores the analysis of the phase, microstructure, electromagnetic interference (EMI) shielding, and microwave absorption properties of the prepared sample of (1-y) [(0.94) BaTiO₃-0.06(BaZrO₃)]-y[Na₂O] ceramics with y = 0, 0.02, 0.04, 0.06, synthesized by high energy planetary ball milling technique. The material was synthesized using solid-state reaction route, followed by calcinations at a temperature of 1100 °C for 2 h and the powder was uniaxially pressed into rectangular plates and circular pellets using a hydraulic press and sintered at 1300 °C for 2 h. XRD, Raman spectroscopy, and FESEM have been used to examine the structural, vibrational, and surface morphology of the ceramics respectively. The synthesized ceramics have shown pure perovskite rhombohedral phase with space group R3c and was well matched with the standard (JCPDS file number COD 47-901-4756. The crystallite size was calculated to be 10.5 nm for y = 0 and was increased from 15.7 nm to 19.6 nm with increasing of Na⁺ doing from y = 0.02 to y = 0.06. The FESEM micrographs reveal a well dense material with a little porosity with average grain sizes of 175 nm, 389.4 nm, 577.6 nm, and 631.2 nm for Na doped BZT ceramics with concentrations of y = 0.00, 0.02, 0.04, and 0.06. Vector Network Analyzer (VNA) measurements demonstrate that the sample with y = 0.02 exhibits the total shielding effectiveness (SE_T) of 36.2 dB and a reflection loss of -89.1 dB at ∼13.5 GHz with 1.5 mm thickness sample. The value of ε′ was measured to be 44.6 at 15.9 GHz for y = 0.02 ceramic. These results suggest that Na doped BZT possesses the potential to efficiently absorb up to 99.99% of electromagnetic interference (EMI) radiation and viable for electromagnetic shielding, IOT, Sensing, Stealth technology, Microwave imaging, 5G mobile applications in high-frequency domains.

In this work, the influence of Cu doping (0, 0.5, and 1.0 mol% Cu) on the structural, ferroelectric, dielectric, and optical properties of the K0.5Na0.5NbO3 (KNN) electroceramic system was investigated. Bulk samples were synthesized via the conventional ceramic method, calcined at 900 °C for 4 h, pressed uniaxially at 385 MPa, and sintered at 1100 °C for two different time intervals:1 and 3 h. The XRD patterns of the calcined powders confirmed the formation of the perovskite structure, and the SEM micrographs of the sintered samples revealed grain sizes between 1 and 2 μm. Hysteresis loops (polarization vs. applied electric field) revealed ferroelectric behavior in the pure KNN and KNN1%Cu samples; in contrast, KNN0.5%Cu showed a pinched hysteresis loop, characteristic of antiferroelectric or aging behavior. Dielectric function as a function of temperature allows identifying the reported temperatures of the crystalline phase transitions of KNN, orthorhombic–tetragonal, and tetragonal–cubic, which occur at approximately 200 °C and 420 °C respectively; the highest temperature corresponds to the Curie temperature, where a transition to the paraelectric phase occurs. First-principles calculations were realized to determine the band structure and density of states for pristine and Cu-doped KNN. The calculated energy gap, E_g, was compared with that measured experimentally, where we found an appreciable reduction in E_g, with Cu doping from 3.13 eV for pure KNN to 1.75 eV for KNN with 1% Cu.

The effect of thermal cycling on certain dielectric, piezoelectric and mechanical properties of 1–3 piezocomposites is studied. In each cycle, the samples are heated to 100° C for 6 h and allowed to cool naturally to room temperature. Electrical admittance spectra are recorded after each cycle and the material parameters are estimated by non-linear regression analysis. The material parameters of the 1–3 piezocomposite, ({K}_{33}^{S}), ({k}_{t}), ({c}_{33}^{D}), tan δ, e₃₃, d₃₃ and ({c}_{33}^{E}) are found to vary initially for low number of thermal cycles and tend towards constant values as the number of cycles is increased. This suggests that the piezocomposite materials undergo de-ageing with thermal cycling. Prolonged heating of 1–3 piezocomposites at 70 °C severely affect the resonance characteristics and further heating to 100 °C results in serious degradation leading to catastrophic failure. During the process of encapsulation, curing of Polyurethane at temperature of about 70 °C for extended periods is found to adversely affect the characteristics of 1–3 piezocomposite transducers. These studies give insight into the limiting factors and help us to prevent degradation in performance of 1–3 piezocomposite transducers under certain situations where they are subjected to thermal cycling and prolonged exposure to high temperatures during operation.

The perovskite oxide has high performance in energy storage and conversion devices. In general perovskite family has great compatibility for renewable energy and optoelectronics devices in modern era. In this research, the compounds (B/Al/Ga)SbO₃ have been explored for their mechanical, structural, electronic, optical and thermoelectric properties. These attributes computed with WEIN2K which is based on density functional theory (DFT). The structural parameters that are derived through energy optimization are calculated using GGA. The structures are proven to be structurally, thermodynamically and mechanically stable. BSbO₃ have ductile behavior, whereas AlSbO₃, and GaSbO₃ exhibits brittle characteristics. The calculated band gaps with TB-mBJ are 2.4 eV, 2.1 eV, and 1.98 eV for BSbO₃, AlSbO₃ and GaSbO₃, respectively. Several optical parameters suggest the highest absorption for all structures in the UV region. The transport characteristics also exhibit good response for all materials suggesting their useful insight for renewable energies.

Manganese oxide (Mn₃O₄) nanoparticles were synthesized via a modified acetate precursor-based sol-gel technique. X-ray Diffraction confirmed the formation of single phase a spinel-type tetragonal hausmannite phase with nanocrystalline features .The average crystallite size 14.80 nm was estimated using the Debye-Scherrer equation. High-Resolution Transmission Electron Microscopy revealed nearly spherical nanoparticles with distinct lattice fringes and polycrystalline nature was further corroborated by selected area diffraction pattern. The dielectric, AC conductivity, impedance and electrical modulus properties were systematically investigated over a broad frequency and temperature range .the observed dielectric response at ( 10 kHz – 2 MHz, 25–300 C ) was strongly governed by interfacial polarization, grain and grain boundary contributions and structural defects .AC conductivity followed Jonhscer’s power law (n < 1 ) indicating a correlated barrier hopping mechanism for charge transport .impedance analysis demonstrated negative temperature coefficient of resistance behavior, consistent with semiconducting characteristics, while modulus studied confirmed non-debye type relaxation dynamics .the enhanced dielectric response, thermally activated conductivity and stable relaxation properties make these for use in high performance capacitors and energy storage devices their semiconducting nature and tunable transport characteristics further open the prospects for nanoelectronics components, sensors and next generation multifunctional dielectric material.

Hydroxyapatites are important and major component of the body and play a vital role in the development of bones and teeth. Although bone regeneration involves various complex biological processes, calcium silicates and phosphates have been proven as important components for bone regenerative properties. The aim of the present study is to study the effect of manganese and gallium doping on the electrical properties in the silicate and phosphate bone materials which can affect the regenerative properties. Source materials were compacted in the form of pellets and processed at 600 °C for sintering and grain growth with and without selenium flux. Processing at 600 °C produced metastable grains transitioning from crystalline to glassy phase and hence and hence easier to merge in existing grains in presence of selenium. Silica rich material showed crystalline bones, and phosphorous rich phases facilitated the glassy behavior. Thermogravimetric analysis (TGA) showed stability up to 350 °C and continuous decomposition at high temperature. We observed that dielectric constant and resistivity for the frequency range of 100 Hz to 100,000 Hz at bias voltage 50 mV to 1000mV did not change, which indicates that breakdown of the ceramic material did not occur despite lower resistivity.

The remarkable properties and wide variety of uses of carbon nanotubes (CNTs) and metal sulfides, like electrical energy storage and energy exchange, have attracted a lot of attention. The creation of a rough-surfaced, highly effective electrode nanomaterial is essential for more advanced high-energy storage technologies. In current research, the well-established cost effective solvothermal approach is used to synthesize the NiS microstructure with a rough surface. The specific capacitance of the NiS-CNT material was 1735 F/g at 1 A/g, which is higher than the natural NiS material alone. Asymmetric supercapacitors have an amazing power density of 4500 W/kg and an energy density of 42.5 Wh/kg when the current density is 1 A/g. An 89% capacitance retention rate after 10,000 cycles shows that the cycling reliability is also very good. The NiS-CNT//AC electrode has better ion and electron transfer capacity, a bigger surface area, and a higher rate capability, which highlights its potential use in electrochemical energy storage.