共查询到20条相似文献,搜索用时 15 毫秒
1.
Muneyasu Suzuki Yuji Noguchi Tetsuo Uchikoshi Masaru Miyayama 《Journal of Electroceramics》2010,24(2):91-96
Magnetic-field-assisted electrophoretic deposition method has been employed for synthesizing a(b)-axis-oriented Bi5FeTi3O15 ceramics, and the effects of grain orientation and microstructure on the polarization and piezoelectric properties have been
investigated. Grain-oriented Bi5FeTi3O15 ceramics with a high relative sintered density of 98% is shown to exhibit enhanced polarization and piezoelectric properties
with a remanent polarization (P
r) of 19 μC/cm2 and a piezoelectric strain constant (d
33) of 23 pm/V, which are much superior to those of randomly-oriented ceramics (P
r of 7 μC/cm2 and d
33 of 5 pm/V). 相似文献
2.
Bi9Fe5Ti3O27 is an eight-layered material belonging to the family of bismuth layered structured ferroelectromagnets. The polycrystalline sample of this compound was prepared by a standard solid-state reaction technique. The formation of the compound in an orthorhombic crystal structure was confirmed by an X-ray diffraction (XRD) technique (lattice parameters: a?=?5.5045[27] Å, b?=?5.6104[27] Å, c?=?76.3727[27] Å). Detailed studies of surface morphology of the compound using scanning electron microscopy (SEM) exhibit that the compound has domains of plate shaped grains. Studies of dielectric and electric properties in a wide temperature range (30–500 °C) at different frequencies (100 Hz–1 MHz) exhibit an anomaly at 291?±?2 °C, which is related to ferroelectric to paraelectric phase transition as suggested by hysteresis loop at room temperature. The values and nature of temperature variation of dc conductivity exhibit the NTCR behavior of the compound. 相似文献
3.
Niobium-doped strontium titanate synthesized via conventional solid-state reaction has been studied. Influence of niobium
content on the lattice parameters and electrical conductivity has been reported. Various reduction conditions have been investigated.
For samples reduced in hydrogen at 1400°C, a transition from thermally activated to metallic behavior has been observed. Maximum
electrical conductivity (ca. 55 Scm−1 at 650°C) has been observed for the SrTi0.98Nb0.02O3-δ sample. The relation of electrical conductivity with the porosity of the samples has been shown. 相似文献
4.
Preparation and electrical properties of sintered bodies consisting of monophase cubic spinel oxides, CrXMn1.5Co(1.0-X)Ni0.5O4 (0 ≦ X ≦ 0.42), were investigated. Specimens with compositions within X = 0.42 were prepared as starting materials. The element of Cr was used to exchange Co3+ in octahedral sites (B sites) with Cr3+ so that the hopping mechanism can be discussed. The sintered bodies with mono cubic spinel structure were confirmed to be prepared by heat-treatment for 48 h in air at 1000 °C to convert them into a cubic spinel structure after sintering at 1400 °C. The semiconductive characteristics of the sintered bodies were determined as p-type because the Seebeck coefficients were all positive. The electrical conduction of the sintered bodies was concluded to be controlled by the small polaron hopping mechanism. In the region 0.1 ≦ X ≦ 0.42, the lattice constant increases and electrical conduction (σ) decreases linearly with increasing Cr concentration. The decrease in σ and the increase in the lattice constant corresponded to the increase in Cr concentration by which the jumping distance of electrons between Mn3+ and Mn4+ is lengthened. 相似文献
5.
Nainjeet Singh Negi Kanchan Bala Jyoti Shah Ravinder K. Kotnala 《Journal of Electroceramics》2017,38(1):51-62
We prepared NiFe2O4/(Pb, Sr)TiO3 (NFO/PST) bilayer films by the chemical solution method and investigated their multiferroic, magnetoelectric and magneto-impedance properties. Multiferroic properties have been observed at room temperature. The bilayer films exhibit saturation polarization P s ? 26.6 μC/cm2 and saturation magnetization M s ? 134 emu/cm3. With increasing Sr content, M s. and P s values of the NFO/PST bilayer films decrease. The variation may be ascribed to the influence of interfacial strain and decrease in tetragonality. High magnetoelectric coupling effect has been observed in the NFO/PST bilayer films with maximum value of α E = 6.35 Vcm?1 Oe?1 measured at H DC ~ 1 kOe and f ~ 10 kHz for Sr ~ 10% (NFO/PST10). The magneto-impedance measurements establish a strong dependence on magnetic field, further confirming magnetoelectric response in NFO/PST bilayer films. An alternative approach for impedance analysis of NFO/PST10 bilayer film provides direct evidence of strain mediated magnetoelectric coupling at room temperature. The results indicate that NFO/PST bilayer films can be considered as a potential multiferroic magnetoelectric material. 相似文献
6.
In this article, (Na0.5Bi0.5)1-xBaxTiO3 lead-free piezoelectric ceramics were prepared by solid-state reaction. The influence of Ba contents on phase structures, compositional distribution and electrical properties of (Na0.5Bi0.5)1-xBaxTiO3 ceramics were systematically investigated to further understand the nature of phase transition. It was found that the phase structure of (Na0.5Bi0.5)1-xBaxTiO3 transforms from rhombohedral to tetragonal symmetry at x = 0.06 ~ 0.07 and Ba2+ segregation forms the coexistence of Ba-rich tetragonal and Ba-deficient rhombohedral phases close to MPB. The electrical properties of prepared samples regularly changed with Ba content, which is closely related to the distribution of rhombohedral and tetragonal phases. The prepared sample near MPB exhibited the largest dielectric constant and the excellent piezoelectric properties (the maximal measuring field reached 78 kV/cm and the piezoelectric constant d 33 = 151pC/N). 相似文献
7.
Calcium cobaltite is one of the most promising oxide p-type thermoelectric materials. The solid-state reaction (or calcination, respectively), which is well known for large-scale powder synthesis of functional materials, can also be used for the synthesis of thermoelectric oxides. There are various calcination routines in literature for Ca3Co4O9 powder synthesis, but no systematic study has been done on the influence of calcination procedure on thermoelectric properties. Therefore, the influence of calcination conditions on the Seebeck coefficient and the electrical conductivity was studied by modifying calcination temperature, dwell time, particle size of raw materials and number of calcination cycles. This study shows that elevated temperatures, longer dwell times, or repeated calcinations during powder synthesis do not improve but deteriorate the thermoelectric properties of calcium cobaltite. Diffusion during calcination leads to idiomorphic grain growth, which lowers the driving force for sintering of the calcined powder. A lower driving force for sintering reduces the densification. The electrical conductivity increases linearly with densification. The calcination procedure barely influences the Seebeck coefficient. The calcination procedure has no influence on the phase formation of the sintered specimens. 相似文献
8.
The stoichiometric CaCu3Ti4O12 pellets were prepared by the solid state synthesis. X-ray diffraction data revealed the tenorite CuO and cuprite Cu2O secondary phases on the unpolished CaCu3Ti4O12 samples regardless of the heating rates. Also, the dielectric constant marked the highest for the CaCu3Ti4O12 sample sintered at the lowest heating rate (1°C/min), which was explained by the increased grain conductivity due to the
cation reactions. On the other hand, Cu2O phase was found only on the unpolished CaCu3Ti4O12 sample sintered over 1100°C and those are considered as the remains reduced from the CuO phase. The higher sintering temperature
showed the increased dielectric constant and the loss tangent of the CaCu3Ti4O12 samples, and this result could be interpreted by the impedance measurement data. The relationship between the processing
condition and the dielectric properties was discussed in terms of the cation non-stoichiometry and the defect chemistry in
CaCu3Ti4O12. 相似文献
9.
Qing Ma Bingbing Wan Lijin Cheng Shaojun Liu Fusheng Liu 《Journal of Electroceramics》2016,36(1-4):30-39
The dependence of structure and piezoelectric response d33 on individual excess A-site K or Na in K0.5Na0.5NbO3 based lead-free piezoceramics is reported. The coexistence of orthorhombic, tetragonal, and monoclinic phases at room temperature is observed in the investigated 0.94K0.5+xNa0.5NbO3–0.06LiNbO3 and 0.94K0.5Na0.5+yNbO3–0.06LiNbO3 ceramics (x, y = 0–0.025). The weight ratio of three phases, orthorhombic-tetragonal phase transition temperature, and d33 value are highly sensitive to A-site K or Na nonstoichiometry. A-site Na nonstiochiometry plays a dominant role in enhancing the electrical properties of KNN by significantly reducing the weight ratio percentage of monoclinic phase and shifting the orthorhombic-tetragonal phase transition temperature to lower temperatures. 相似文献
10.
This paper reports re-crystallization behaviour of 60ZnO-30B2O3-10SiO2 pure glass. Influence of different fillers on the re-crystallization is also highlighted. Irrespective of the nature of the filler, glass transition temperature (Tg) remains the same as that of the pure glass at 570 °C. The onset crystallization temperature is enhanced by 15 to 25 °C owing to filler addition. The peak crystallization temperature corresponding to Zn3B2O6, ZnB2O4 and willemite occurs at 735, 810 and 851 °C for the pure glass. In the presence of alumina, gahnite emerges first at 700 °C followed by ZnB2O4 phase. With mullite as filler, initially ZnB2O4 and willemite formed at 700 °C and gahnite phase emerged only at 750 °C and peaks at 787 °C. In the presence of fused silica only ZnB2O4 and willemite phases were observed. The dielectric properties of the pure glass and that of the glass + fillers are also reported. Re-crystallization of various low K phases ensures good dielectric porpertis with reduced glass content after sintenring. 相似文献
11.
In this letter, MnO2-doped (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT-6) lead-free piezoelectric ceramics were synthesized by solid state reaction, and the microstructure and electrical
properties of the ceramics were investigated. X-ray diffraction (XRD) reveals that all specimens take on single perovskite
type structure, and the diffraction peaks shift to a large angle as the MnO2 addition increases. Scanning electron microscopy shows that the grain sizes increases, and then decreases with increasing
the MnO2 content. The experiment results indicate that the electrical properties of ceramics are significantly influenced by the MnO2 content, and the ceramics with homogeneous microstructure and excellent electrical properties are obtained with addition
of 0.3 wt% MnO2 and sintered at 1160°C. The piezoelectric constant (d33), the electromechanical coupling factor (k
p
), the dissipation factor (tan δ) and the dielectric constant (ɛ
r
) reach 160 pC/N, 0.29, 0.026 and 879, respectively. These excellent properties indicate that the MnO2-doped BNBT-6 ceramics can be used for actuators. 相似文献
12.
Bo Li Zhenjun Qing Yingxiang Li Hao Li Shuren Zhang 《Journal of Electroceramics》2016,37(1-4):145-150
CaO-Al2O3-SiO2 glass-ceramic were prepared by melt quenching technique. The crystallization behavior and properties were studied by means of a non-isothermal, thermal analysis technique, X-ray diffraction and scanning electron microscopy. The influence of sintering temperature on phase formation, microstructure, bending strength, dielectric and thermal properties were determined. The activation energy of crystallization and the Avrami parameter were also discussed. The X-ray diffraction results show that SiO2 phase could be found in all samples and CaSiO3 and anorthite phases could only be observed in the samples sintered at above 875°C. The densification of glass-ceramic starts at 730°C after the liquid glass is formed and stops at 803°C. Complete densification was achieved at 875°C and the highest mechanical strength was obtained at 850°C, but density significantly decreased at higher temperatures. The coefficient of thermal expansion and the dielectric constant increase with the increasing sintering temperature. The value of the Avrami parameter (n) is ~1.6 and the apparent activation energy (E) is 298 kJ/mol. 相似文献
13.
The ternary lead-free piezoelectric ceramics system of (1 – x) [0.88Na0.5Bi0.5TiO3-0.12K0.5Bi0.5TiO3] – xNaNbO3(x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by conventional solid state reaction method. The crystal structure, dielectric, piezoelectric properties and P-E hysteresis loops were investigated. The crystalline structure of all compositions is mono-perovskite phase ascertained by XRD, and the lattice constant was calculated from the XRD data. Temperature dependence of dielectric constant r and dissipation factor tan measurement revealed that all compositions experienced two phase transitions: from ferroelectric to anti-ferroelectric and from anti-ferroelectric to paraelectric, and these two phase transitions have relaxor characteristics. Both transition temperatures Td and Tm are lowered due to introduction of NaNbO3. P-E hysteresis loops show that 0.88Na0.5Bi0.5TiO3-0.12K0.5Bi0.5TiO3 ceramics has the maximum Pr and Ec corresponding to the maximum values of electromechanical coupling factor Kp and piezoelectric constant d33. The piezoelectric constant d33 and electromechanical coupling factor Kp decrease a little, while the dielectric constant 33T/0 improves much more when the concentration of NaNbO3 is 8 mol%. 相似文献
14.
0.62Bi(Mg1/2Ti1/2)O3-0.38PbTiO3-xwt%Bi2O3 (BMT-0.38PT-xBi2O3) ceramics were prepared by conventional powder-processing method. It indicated that the morphotropic phase boundary (MPB) region located in 0.0?≤?x?≤?0.3. For x?=?0.3, it exhibited good piezoelectric properties, d33 ~245pC/N and kp ~40 %. With the increase of Bi2O3 content, the Curie temperature (Tc) was found to increase, and the dielectric loss was found to decrease above 200 °C compared with BMT-0.38PT sample. Finally, it can be found that depolarization temperature was around 350 °C by thermal depoling method. 相似文献
15.
Gunnar Suchaneck Vinay S. Vidyarthi Marianne Reibold Alexander Deyneka Lubomir Jastrabik Gerald Gerlach Johannes Hartung 《Journal of Electroceramics》2008,20(1):17-20
Pb(Zr,Ti)O3 (PZT) thin films deposited on insulating ZrO2 buffered silicon wafer are intended to be employed for in-plane polarized piezoelectric MEMS devices. Multi-target reactive
sputtering system for large area deposition of in-situ crystallized PZT thin films and the ZrO2 buffer layer has been employed. The interface analysis of multilayer structures by high resolution transmission microscope,
X-ray diffraction, optical refraction, and absorption spectra studies has been presented. At a substrate temperature of 520°C
and excess lead deposition condition, the formation of a PZT superstructure has been revealed. The substrate temperature of
580°C leads to the crystallization of PZT directly into a single phase perovskite crystal structure. A pronounced Urbach behavior
in our PZT thin films has been observed by optical absorption studies. The surface roughness of PZT films deposited on a ZrO2 buffer layer is much higher than that on conducting platinized silicon wafer. 相似文献
16.
Guo-Zhong Zang Xiu-Jie Yi Zhi-Jun Xu Xi-Peng Pu Peng Fu Li-Min Zhao 《Journal of Electroceramics》2010,25(1):85-88
Lead-free (1-x)(K0.5Na0.5)0.95(LiSb)0.05Nb0.95O3-xBaTiO3 (abbreviated as (1-x)KNNLS-xBT) piezoceramics were synthesized by conventional solid state sintering and the effect of BaTiO3 on the microstructure, dielectric and piezoelectric properties was investigated. It was found that both orthorhombic-tetragonal
(T
O-T) and tetragonal-cubic (T
C) phase transition temperatures decreased obviously with increasing BaTiO3 content. Although proper amount of BaTiO3 facilitated the sintering of (1-x)KNNLS-xBT ceramics, the addition of BaTiO3 affected the relaxor behavior slightly and it was not beneficial to improve piezoelectric strain coefficient d
33, remnant polarization P
r and piezoelectric coupling constant k
p. 相似文献
17.
Jan Suchanicz Irena Jankowska-Sumara Tatiana V. Kruzina 《Journal of Electroceramics》2011,27(2):45-50
Lead-free Na0.5Bi0.5TiO3 -BaTiO3 ceramics have been prepared in the whole range of concentrations and studied at room-temperature by means of X-ray, Raman
scattering and infrared techniques. X-ray measurements revealed rhombohedral, rhombohedral-tetragonal boundaries and tetragonal
modifacations depending on the contents of BaTiO3. The distinct changes of the Raman and infrared spectra with increasing of BaTiO3 content, which were correlated with X-ray results, were observed. The broad phonon spectra indicated the disorder in the
A site of Na0.5Bi0.5TiO3 -BaTiO3 system. 相似文献
18.
MgTiO3/CaTiO3 layered ceramics with differently stacking were fabricated and the microwave dielectric properties were evaluated with TE011 mode. With increasing CaTiO3 thickness fraction, the resonant frequency decreased and the dielectric constant increased with a near-linear relation for
the bi-layer ceramics, while the values of the tri-layer MgTiO3/CaTiO3/MgTiO3 ceramics with thickness ratio of 1:1:1 derived much from the curves of the bi-layer ceramics. The finite element method was
used to give an explanation for the differences between the bi-layer and tri-layer ceramics. 相似文献
19.
(Ca1-xFex)3Co4O9 polycrystalline samples (x?=?0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.1 and 0.2) have been prepared by solid state reaction and sintered by spark plasma sintering. Their thermoelectric properties have been studied between 323 and 1000 K. The substitution limit is low (< 3%). For higher iron contents, formation of Co3O4, Ca2FeCoO5 and a calcium ferrite compound occurs. Concerning electrical conductivity and power factor, an optimum value exists for x?=?0.03 substitution. This optimum power factor is circa 10% higher than the one of the unsubstituted sample. The optimum thermal diffusivity is measured for the sample with x?=?0.02 and is circa 9% lower than the one of the unsubstituted sample. Therefore, the dimensionless figure of merit ZT is finally increased by 14% for the (Ca0.98Fe0.02)3Co4O9 and (Ca0.97Fe0.03)3Co4O9 compositions. 相似文献
20.
Particulate composites of (1-x) BaTi0.85Sn0.15O3 – x NiFe2O4 (with x?=?5, 10,15 and 20 wt%) were synthesized using the solid-state reaction method by sintering at 1350 °C for 4 h. Formation of the diphase composites was confirmed by X-ray diffraction (XRD) and Fourier Transform Infra-red (FTIR) techniques. Temperature (RT-200 °C) and frequency (20 Hz- 1 MHz) dependent of AC conductivity, dielectric constant and dissipation have been studied. The dielectric constant exhibits strong frequency dispersion in the range 20 Hz-1 kHz which is attributed to Maxwell-Wagner interfacial polarization occurring at grain-grain-boundaries interface/interface of grains of BTS-NF. The M-H curve of all the composites exhibited a hysteresis loops typical charcateistic of a ferromagnetic material. The ferromagnetic ordering in the composites on account of NiFe2O4 as a constituent is explained using bound magnetic polarons (BMPs) model. The experimental magnetic data have been fitted to BMP model. Value of Ms is smaller, whereas of Hc and Mr are higher of the composites compared to value for NiFe2O4. The temperature at which divergence in the M vs. T plot in ZFC and FC starts is higher for the composites than for NiFe2O4. 相似文献