Dielectric characteristics of Ba(Fe1∕2Nb1∕2)O3 ceramics were investigated over a broad temperature and frequency range. Two dielectric relaxations following Arrhenius law observed at 150–400 406–650K. An extremely high relaxorlike peak (202 270 5Hz, 91 930 1kHz, 37 030 100kHz) with very strong dispersion was 406–650K, it not relaxor ferroelectric but an oxygen defect induced abnormity. The significant drop constant 146–400K also dependent, nearly Debye relaxation. Between these two...

Abstract CaTiO 3 is a typical linear dielectric material with high constant, low loss, and resistivity, which expected as promising candidate for the energy storage density applications. In previous work, an of 1.5 J/cm was obtained in ceramics, where strength only 435 kV/cm. fact, intrinsic predicted 4.2 MV/cm. Therefore, it should be challenge issue to enhance ceramics by optimizing microstructures. present dense fine uniform microstructures are prepared spark plasma sintering, greatly...

BiFeO 3 multiferroic ceramics were modified by introducing CaTiO . The stability of perovskite was increased the present modification, and single‐phase ( Bi 1 − x Ca )( Fe Ti ) O solid solutions obtained when ≥ 0.15, where symmetry changed from R c ≤ 0.2) to Pbnm 0.3). ferroelectric property enhanced because reduction leakage current increase resistivity. dielectric constant, decreased loss, remnant magnetization M r also obtained. best combination characteristics achieved at = 0.2.

Improvement of electrocaloric effect was investigated in the lead‐free undoped and Mn ‐doped Ba 0.65 Sr 0.35 TiO 3 ceramics prepared by spark plasma sintering process. Owing to merit process, a fully dense with fine grain sizes could be obtained. The ( EC ) can significantly enhanced from 0.83 K for conventional sintered 3.08 plasma‐sintered since dielectric strength dramatically increased. This work indicated an effective way achieve system at room temperature.

The structure and microwave dielectric properties of SrLaAl_1−x(Zn_0.5Ti_0.5)_xO₄ceramics were determined in the composition range of<italic>x</italic>= 0–0.9.

The hybrid improper ferroelectricity (HIF) has been proposed as a promising way to create multiferroic materials with strong magnetoelectric coupling by the first-principle calculation, and experimental evidences of HIF in Ruddlesden-Poper Ca3(Ti1−xMnx)2O7 (x = 0, 0.05, 0.1, 0.15) ceramics have shown present work. room temperature ferroelectric hysteresis loops are observed these ceramics, polar orthorhombic structure two oxygen tilting modes confirmed X-ray powder diffraction. A first-order...

After decades of study, BiFeO 3 is still the most promising single‐phase multiferroic material due to its large polarization and high operating temperature, drawing much attention. As a typical type‐I material, magnetoelectric coupling in deemed be weak different origins ferroelectricity magnetism. Here, effect bulk readdressed both theoretically experimentally. Based on Dzyaloshinsky–Moriya interaction scenario, actually strong, with energy about 1.25 meV magnetism‐coupled parasitic...

Dielectric spectra of Sr(Fe1∕2Nb1∕2)O3 ceramics were characterized in wide temperature (123–623K) and frequency (100Hz–1MHz) ranges. Two dielectric relaxations with strong dispersion following the Arrhenius law detected low high ranges, respectively, between them there was a giant constant step. The relaxorlike peak could be almost completely removed by annealing O2, it should assigned to defect ordering induced relaxor behavior, while relaxation proposed stem from electronic...

Dielectric relaxations of Ba(Fe1∕2Ta1∕2)O3 ceramics were investigated and discussed over a broad temperature frequency range. Two dielectric following Arrhenius law observed at 153–382 440–623K, where there was giant constant step between them. The dependent rapid drop 153–382K nearly Debye relaxation with the intrinsic nature, while high an extremely peak very strong dispersion attributed to defect ordering but not typical relaxor ferroelectric behavior. O2 annealing almost completely...

The crystal structure refinement and infrared reflectivity study were carried out for SrRAlO4 (R = Sm, Nd, La) ceramics with K2NiF4 to investigate the correlations between structure, polar-phonon mode parameters, microwave dielectric properties. Fourier transform spectra in range of 50−4000 cm−1 measured evaluated by means classical oscillator fit. data extrapolated below frequency estimate intrinsic losses. Heavy distortions (Sr,R)O9 dodecahedra AlO6 octahedra are observed they should...

A new<italic>n</italic>= 2 type Ruddlesden–Popper compound Sr₂LaAlTiO₇was synthesized and characterized, the microwave dielectric properties were investigated together with their microstructures.

A modified indirect algorithm for extracting real permittivities from measured resonant frequencies has been developed. It is based on the perturbation theory along with Newton iteration method, and improves speed of calculation a factor 2-4. superior, especially when system matrices under are large. Based complementary advantages direct algorithm, mixed high accuracy described. measurement incorporating linear fractional curve-fitting method built to measure complex high-Q materials.

The dielectric and ferroelectric characteristics of ( Sr x Ba 1− ) Nb 2 O 6 unfilled tungsten bronze ceramics have been investigated together with the structure. present vary significantly , A1/A2‐sites occupancy has determined as primary parameter governing this variation tendency. ions tend to occupy A2‐sites, A1‐sites, one A1‐site is empty. When ratio / close 1:4 (where four A2‐sites are just occupied by ions, ion while another empty), normal transition observed anomaly in tanδ– T curve =...

The evolution of structure, ferroelectric, and piezoelectric properties in Bi1−xSmxFe0.99Ti0.01O3 ceramics was extensively investigated within the entire morphotropic phase boundary region with 0 ≤ x 0.20. A sequential transition R3c-Pna21-Pbnm increasing Sm content revealed by Rietveld refinement X-ray diffraction data together macroscopic ferroelectric measurements. Both showed a great enhancement vicinity R3c/Pna21 (polar-to-polar) boundary, which should be caused field-induced between...

Abstract BiFeO 3 is recognized as the most important room temperature single phase multiferroic material. However, weak magnetoelectric (ME) coupling remains a key issue, which obstructs its applications. Since in essentially hindered by cycloidal spin structure, here efforts to improve destroying state and switching ferromagnetic through symmetry modulation are reported. The structure tuned from polar R3c Pna2 1 , finally nonpolar Pbnm forming Bi 1‐ x Nd FeO solid solutions, where two...

Two mononuclear octahedral Co(II) complexes, [Co(L)X2] (L = 1-(prop-2-en-1-yl)-1H-imidazole, X NCS− (1) and NCSe− (2)), have been synthesized characterized. The central ions in two complexes adopt an geometry, coordinated by four N atoms from the ligand anion. Direct-current magnetic data revealed large easy-plane anisotropy both 1 2. Dynamic measurements demonstrated that 2 display field-induced slow relaxation. For 2, Raman mechanism is found to dominant process whole temperature range....

This study investigated the inhibitory effect and mechanism of modified ultrafine ABC powder on explosion a methane (CH4)/coal dust mixed system. Through experiments, it was found that addition significantly weakened deflagration characteristics CH4/coal mixture During decomposition, heat absorbed to generate ammonia phosphoric acid. Inert gases such as CO2 water vapor produced during decomposition could dilute oxygen concentration. Phosphate ions ammonium phosphate would bind with free...

Dielectric relaxations of charge-ordered Ln1.5Sr0.5NiO4 (Ln=La and Nd) ceramics were investigated over a broad temperature range. The giant dielectric constant (over 70 000) with low loss ∼0.1 was determined at high frequencies (up to 5 MHz) There are two in the vicinity charge ordering temperatures. thermal activated small polaronic hopping between temperatures should contribute response present ceramics. Compared other materials, materials have notable advantage for frequency applications.

Ba[(Zn 1− x Mg ) 1/3 Nb 2/3 ]O 3 ceramics were synthesized by the solid‐state reaction process, and their microstructure microwave dielectric properties investigated. Surface secondary phase Ba 5 4 O 15 due to ZnO loss during sintering was detected for all compositions except =1.0. 2+ substitution increased order–disorder transition temperature ‐substituted well ordered at a rather high temperature. The constant τ f decreased approximately in same linear trend =0.6 0.8, while Q values...

Dielectric properties of La2CuTiO6 ceramics were investigated in a broad frequency and temperature range. There is only one dielectric relaxation the curve dependence for ceramics. This thermal activated process. The bulk grain boundary resistances can be obtained from results least-mean-square fitting on impedance spectra. conduction mechanism present also activation energy almost same as that electrical conductivity this indicates closely correlation between conductivity. should attributed...

In the present work, structure, magnetic, and dielectric characteristics of Nd2NiMnO6 Sm2NiMnO6 have been investigated with comparison to those for La2NiMnO6. The magnetic properties ceramics vary decreasing lanthanide ionic radius (RLn). Both are ferromagnetism monoclinic symmetry (space group P21/n). Curie temperature TC is 194 K 156 K, respectively, it decreases 〈Ni-O-Mn〉 bond angle which depends on RLn. Meanwhile, constant ε′ monotonically similar variation tendency RLn indicates that...