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The A-site rare earth-doped Bi₄Ti₃O${}_{12}$ (BTO) has been highly interested in nonvolatile ferroelectric random memory devices, piezoelectric devices, electro-optical devices, capacitors, sensors, transducers, etc., due to its low coercive field and superior fatigue resistance properties. However, single B-site doping has not received corresponding attention. In this work, BTO and Bi₄Ti${}_{3.9}$Sn${}_{0.1}$O${}_{12}$ (BTS) thin films were prepared by sol–gel method, in which the doping of Sn effectively restrained the grain growth and decreased the grain size, as well as diminished the formation of oxygen vacancies and enhanced the breakdown field. This leads to a significant enhancement of the ferroelectric properties of the BTO films. The final BTS films exhibit excellent saturation P–E loops with a remnant polarization (2$P_r$) of 94.4$\mu$C/cm² and a coercive field (2$E_c$) of 0.69MV/cm at a maximum electric field of 2.8MV/cm. The ferroelectric fatigue and dielectric properties of BTS film were also characterized. The results suggest that doping of Sn at B-site can effectively improve the breakdown strength and enhance the ferroelectric properties of the BTO film.

Using effective-field theory with correlations, we investigate the effects of interfacial pseudo-spin coupling fluctuations on the susceptibility and polarization of ferroelectric superlattices within the framework of transverse Ising model. It is found that the interfacial coupling fluctuations increase the susceptibility in the low temperature region. For a strong interfacial coupling, the phase transition temperature decreases with the strength of fluctuations of the interfacial coupling. The dependence of the susceptibility on the superlattice period of BaTiO₃/SrTiO₃ are plotted for different interfacial coupling fluctuations strength. At room temperature, when the interfacial coupling fluctuation increases, the peak position of the susceptibility will shift to a large superlattice period.

In the work nano silica has been irradiated by 2×10¹³ cm^-2s^-1 neutron flux at different times up to 20 h. The temperature and frequency dependencies of real and imaginary parts of dielectric constant of the nanomaterial exposed to neutron flux influence and initial state has been comparatively analyzed. From analysis results it has been revealed that the permittivity of nano SiO₂ increases in general tendency with influence of neutron flux. The mutual dependence of the real and imaginary parts of dielectric constant of nano SiO₂ particles has been reviewed. From the cases similar to Cole–Cole diagrams existing in the dependencies it has been revealed that the value of the relaxation period is compatible with polarization of the nano particles. It has been observed an increase in polarization with increase of influence period of neutron flux. Mechanisms of all effects observed in the experiments have been given.

The heterolayered BT/BNT thick films were fabricated by screen printing techniques on alumina substrates electrodes with Pt. Their structure and ferroelectric properties were investigated with the heterolayered tetragonal/rhombohedral structure composed of the BT and the BNT thick films. The structural and electrical properties of the heterolayered BT/BNT thick films were studied. The dielectric properties such as dielectric constant, loss and remanent polarization of the heterolayered BT/BNT thick films were superior to those of single composition BNT, and those values for the heterolayered BT/BNT thick films were 1455, 0.025 and 12.63 µC/cm².

Pt/Ba${}_{0.6}$Sr${}_{0.4}$TiO${}_3$ (BST)/MgO interdigital capacitor (IDC) was patterned from a Pt/BST/MgO heterostructure, in which Pt film was prepared by sputtering and epitaxial BST film by pulsed laser deposition (PLD). Post-annealings at 200${}^{\circ }$C and 750${}^{\circ }$C were successively applied to the sample in order to investigate the impacts of post-annealing on the structural and dielectric properties of the IDC. The dielectric constants of the sample for as-grown and annealed at 200${}^{\circ }$C and 750${}^{\circ }$C were 1529, 1717 and 1800 and the corresponding dielectric losses were 0.073, 0.062 and 0.059, respectively. This is attributed to the fact that 200${}^{\circ }$C annealing can improve the quality of Pt/BST interface and 750${}^{\circ }$C annealing can reduce the oxygen vacancies in BST film. Our results provide the evidences that both the interface and oxygen vacancy play very important roles in dielectric properties of BST-based IDCs.

The strontium-modified barium titanate $({\mathrm{\text{Ba}}}_{0.7}{\mathrm{\text{Sr}}}_{0.3}{\mathrm{\text{TiO}}}_3)$ ceramic was fabricated by high temperature compound reaction route. The pattern of X-ray diffraction confirms a single-phase compound with better crystallization. The dielectric properties (permittivity/loss) are investigated as a function of temperature and frequency. The relaxation mechanism and correlation with the physical properties are studied using complex impedance spectroscopy. The Nyquist plot shows the association of various effects (grain and grain boundary) by fitting electrical circuits at various temperature regions. This study tells the nature and conduction mechanism of the prepared sample. The Jonscher’s universal power law is being followed by the frequency-dependent ac conductivity.

With the miniaturization of electronic products, the portability and the critical need of clean energy for environment have led to the development of lead-free electroceramics. In this work, lead-free dielectric ceramics of 0.94Na${}_{0.5}$Bi${}_{0.5}$TiO₃–0.06BaTiO₃ (NBT–0.06BT) are synthesized by wet solid-phase method. The effects of calcination temperature on phase structure, morphology, densification behavior and dielectric properties are investigated. The XRD results indicate that all samples demonstrate typical diffraction peaks of perovskite structure. The SEM and dielectric analytical results show that high-performance dielectric property of NBT–0.06BT ceramic with dense microstructure and appropriate grain size can be achieved when the calcination temperature is appropriate.

Cu-doped SiC nanopowders have been prepared via combustion synthesis of the silicon and carbon system in a 0.1 MPa nitrogen atmosphere under different reaction time, using copper as the dopant and PTFE as the chemical activator, respectively. X-ray diffraction, scanning electronic microscope and Raman spectra have been used to characterize the phase and morphology of prepared nanopowders. Results indicate that the lattice constant of prepared Cu-doped SiC nanopowder decreases with extending reaction time. The prepared nanopowders have fine spherical particles and narrow particle size distribution and the particle size increases with increasing reaction time. The electric permittivities of prepared Cu-doped SiC nanopowders in the frequency range of 8.2–12.4 GHz have been determined. The real part ε′, imaginary part ε′′ and dielectric loss tgδ of complex permittivity decrease with increasing reaction time. All prepared Cu-doped SiC nanopowder exhibits good microwave absorption property in the frequency range of 8.2–12.4 GHz.

Barium dititanate (BaTi₂O₅) ceramics with high density and phase purity were fabricated by spark plasma sintering (SPS) from the sol–gel derived powders. The fine grained ceramics exhibited a diffuse phase transition which is qualitatively the same as the conventional defects induced relaxor behavior but different in high transition temperature and weak diffuseness. Furthermore the dielectric constant of the present BaTi₂O₅ ceramics showed an abnormal enhancement under the dc bias. The tunability can reach 58%. This can be explained by the favor of b-axis during the cooling process with the help of the dc bias.

${\mathrm{\text{BaTiO}}}_3$/${\mathrm{\text{SrTiO}}}_3$ (BTO/STO) multilayer films were successfully prepared on (La, Sr)${\mathrm{\text{CoO}}}_3$-coated (100) ${\mathrm{\text{SrTiO}}}_3$ substrates by using a radio-frequency (RF) magnetron sputtering process at $700^{\circ }$C. Benefiting from the flexible deposition configuration of a multi-target sputtering system, we were able to tune the dielectric properties of the multilayer film by varying the number of multilayer periods $N$ and the individual layer thickness $d$. It was found that, in a superlattice-like structure ($d_{\mathrm{\text{BTO}}}=d_{\mathrm{\text{STO}}}$=4 nm, $\sim$ 10 unit cells), the dielectric constant increased and the loss tangent decreased with an increasing $N$, especially in the high frequency range ($10^4–10^6$Hz). This can be attributed to a reduced volumetric contribution to the dielectric property from the leaky interface capacitor layer, which lies between the multilayer film and the (La, Sr)${\mathrm{\text{CoO}}}_3$ electrode. On the other hand, as the individual layer thickness $d$ exceeds the superlattice limit ($d_{\mathrm{\text{BTO}}}=d_{\mathrm{\text{STO}}}$=8 nm, $\sim$ 20 unit cells), the superlattice strain effect disappeared and the dielectric constant value dropped by $\sim$50%. However, owing to the reduced number of interfaces and associated defects, the dielectric loss of the multilayer film with a larger period was reduced significantly, as compared to its superlattice counterpart with the same thickness and more periods. The dielectric loss power density of the former was about one order of magnitude lower than that of the latter. These observations provide a solid foundation for using RF magnetron sputtering as an effective method to prepare various forms of multilayer film capacitors for integrated device applications.

High dielectric-permittivity (Ca_0.5Cu_0.5)TiO₃-based ceramics have been prepared by a sol-gel method combined with a solid state sintering process. The results indicate that the additives of H₃BO₃ have a remarkable effect on the sintering temperature, microstructure and dielectric properties. High density (Ca_0.5Cu_0.5)TiO₃ bulk ceramics can be obtained after sintering at 900°C. The as-sintered ceramics show high dielectric constants (~1000), and low losses (~0.05). The dielectric properties are nearly independent of frequency and temperature in a wide range. The activation energy is calculated as about 0.50 eV by impedance spectrum method.

Effects of the Co₃O₄ nanoparticle on the phase formation, microstructure and dielectric properties of barium titanate ceramics are investigated in this study. Co₃O₄-doped BaTiO₃ ceramics were prepared by the conventional mixed oxide method followed by normal sintering in air. Systematic studies of X-ray diffraction (XRD), scanning electron microscopy and dielectric spectroscopy with varying doping levels were performed. The cell parameters, tetragonality and crystallite size of doped ceramics also were calculated from XRD data. Results showed that the single phase of BaTiO₃ gave no evidence of unwanted peak forms in any of the samples. Cubic phase occurred after adding Co₃O₄ at 0.25 mol%. Various grain sizes and shapes were found in this system. Finally, adding Co₃O₄ in BaTiO₃ ceramics resulted in shifting of the Curie point to a lower temperature. The composition, x = 0.25, showed different dielectric behavior, which related to appearance of the cubic phase and fine grain microstructure.

Composites have been extensively studied for dielectric and related applications. This is a review of polymer based 0–3 composites that exhibit a high dielectric constant. These composites are classified into two types: Dielectric–dielectric composite and conductor–dielectric composite. The physical principles and related models are presented with associated assumptions and approximations. In general, a dielectric–dielectric composite needs a higher concentration of the fillers to reach a high dielectric constant than a conductor–dielectric composite. The high dielectric constant observed in the conductor–dielectric composites is usually associated with a high dielectric loss and a low electric breakdown field. The experimental results are summarized to illustrate the principles for, and the achievements in, the development of these composites. The challenges facing the fundamental understanding and the further development of these composites for different applications are discussed.

The Ba_0.3Sr_0.6Ca_0.1TiO₃ (BSCT) powder was prepared through the solid-state reaction. And then preparing ceramic samples with quantitative doped-Bi₂O₃⋅3TiO₂ and different doped-MgO. X-ray diffractometer (XRD) and scanning electron microscopy (SEM) were used to investigate the phase compositions, distribution and morphology of the ceramic samples. SM–11J49 capacitance measurement instrument and CS2674A pressure tester were used to measure the dielectric properties of the samples. The results show that the compactness and the dielectric constant of the ceramics increases first and then decreases when the doped MgO content was changed from 1.5 to 4.5 wt.%. The trend of breakdown strength is characterized by M-shaped pattern with the increase of doped-MgO content. Calculation results demonstrate that when the doped-MgO content is 2.0%, the samples have the highest energy storage density.

In this work, crystal growth and characterization of PIN–PMN–PT (29–59% PIN and 28–35% PT) were conducted to understand how PIN ratio in the PIN–PMN–PT system impacts its phase stability during crystallization. High-quality PIN–PMN–PT crystals with 36% PIN were obtained using the self-seeded Bridgman process, even though the cubic phase In₂O₃ formed at the very beginning of solidification. The melt became more unstable when the PIN ratio in the PIN–PMN–PT system increased to 49% and above, which affected the composition and quality of the as-grown crystals significantly. By increasing the PIN to 36% in PIN–PMN–PT crystal, the rhombohedral-to-tetragonal phase transition temperatures and the coercive field reached 115–135°C and 4.5~5.6 kV/cm, respectively, that greatly expanded the operation domains compared to PMN–PT crystals.

Ferrite ceramics, Ni${}_{0.88}$Zn${}_{0.07}$Co${}_{0.05}$Fe${}_{1.98}$O₄, with the addition of 4wt.% Bi₂O₃ as sintering aid, were fabricated by using a simple one-step processing without involving the step of calcination. X-ray diffraction (XRD) results indicated that single phase ferrite ceramics can be achieved after sintering at 1000${}^{\circ }$C for 2h. The samples demonstrated relative densities in the range of 97–99%. Desired magneto-dielectric properties have been approached by adjusting the sintering temperature and sintering time duration. This technique is believed to be applicable to other ceramic materials.

Bismuth ferrite (BFO) nanostructures and thin films have gained attraction as suitable candidates for energy storage and energy conversion due to their high energy storage efficiency, temperature stability and low dielectric loss. Electrical properties of such multiferroic materials are tailored by ferroelectric and ferromagnetic constituents and have opened up amazing avenues in electrochemical supercapacitor and photovoltaic applications. Dopants play a significant role in optimizing the magnetic and dielectric properties of such materials owing to suitable applications. This review highlights the scientific advancements reported in BFO nanostructures for energy applications by optimizing their magnetic and dielectric properties. This paper starts with a brief introduction of BFO and a discussion on the effects of various dopants by different synthesis techniques, and their effects on the magnetic and dielectric properties are also portrayed. Eventually, this review summarizes the various doping effects, which paves way for future research on this multiferroic material.

This study focuses on the properties of Vanadium and Copper co-doped Barium Zirconate Titanate (BZT) for potential technological applications. Various doping ratios of CuO:V₂O₅ were used to synthesize the materials, and X-ray diffraction (XRD) confirmed a tetragonal phase in all samples. The grain density and dimensions decreased with higher concentrations of V₂O₅ and CuO. FTIR spectra confirmed the compositional structure and bonding of the samples. The impedance analysis indicated that higher doping concentrations facilitated charge conduction at grain boundaries. Dielectric relaxation was studied using the Havriliak–Negami model and electrical modulus behavior was analyzed. Activation energy values from Arrhenius fitting matched those from impedance data, suggesting the same type of charge carriers. The study revealed that elevated levels of V concentration induced charge carriers to exhibit hopping behavior, thereby enhancing conductivity. Conversely, higher Cu concentration impeded hopping, leading to a swift rise in activation energy.

Via the method of cold sintering with post-annealing, the lead-free ceramics ${\text{K}}_{0.45}$${\text{Na}}_{0.45}$${\text{Li}}_{0.1}$NbO₃ were prepared. The cold sintered pellet without post-annealing shows a relative density (${\rho }_r)$ of 77.9%, which is larger than ${\rho }_r$ of the green pellet via the conventional solid-state sintering (SSS) method ($\sim 65.1\%$). The cold sintered pellets were post-annealed at temperatures between $975^{\circ }$C and $1075^{\circ }$C. The effect of post-annealing temperatures on microstructure, dielectric, ferroelectric and piezoelectric properties of the ceramics was studied in detail. After being post-annealed, the relative densities and grain sizes of the ceramics were increased. The ceramics post-annealed at $1050^{\circ }$C show excellent dielectric, ferroelectric and piezoelectric properties. Compared to the conventional SSS method, the method of cold sintering with post-annealing is successful in preparing dense ${\text{K}}_{0.45}$${\text{Na}}_{0.45}$${\text{Li}}_{0.1}$NbO₃ lead-free ceramics in a wide temperature range and at relatively low temperatures.

Dielectrics with high permittivity and temperature stability are important for the development of high-temperature multilayer ceramic capacitors (MLCCs). In this study, Ca${}_{1-x}$Na_xTi${}_{1-x}$Nb_xSiO₅ (abbreviated as CTS$-x$NN) ceramics were prepared by solid-phase reaction method. The introduction of NN weakens the long-range ordered displacement of Ti, leading to a significant increase in the dielectric temperature stability. The CTS−2%NN samples exhibit high permittivity (53) and TCC $\le \pm 170$ ppm/^∘C in the range of $-55^{\circ }$C to 300^∘C. The CTS-based ceramics behave high dielectric temperature stability. In addition, the bandgap of the CTS-based ceramics increased significantly, which is favorable for improving the breakdown strength of the material. For $x=4$% samples, the breakdown strength reaches 621kV/cm. Thus, the designed CTS-based dielectrics are promising for high-temperature capacitors.