共查询到20条相似文献,搜索用时 15 毫秒
1.
Bo Wu Jian Ma Wenjuan Wu Min Chen 《Journal of Materials Science: Materials in Electronics》2017,28(3):2358-2365
In this work, (Ba0.96Ca0.04)(Ti0.92Sn0.08)O3–xmol MnO (BCTS–xMn) lead-free piezoelectric ceramics were fabricated by the conventional solid-state technique. The composition dependence (0 ≤ x ≤ 3.0 %) of the microstructure, phase structure, and electrical properties was systematically investigated. An O–T phase structure was obtained in all ceramics, and the sintering behavior of the BCTS ceramics was gradually improved by doping MnO content. In addition, the relationship between poling temperature and piezoelectric activity was discussed. The ceramics with x = 1.5 % sintering at temperature of 1330 °C demonstrated an optimum electrical behavior: d 33 ~ 475 pC/N, k p ~ 50 %, ε r ~ 4060, tanδ ~ 0.4 %, P r ~ 10.3 μC/cm2, E c ~ 1.35 kV/mm, T C ~ 82 °C, strain ~0.114 % and \(d_{33}^{*}\) ~ 525 pm/V. As a result, we achieved a preferable electric performance in BaTiO3-based ceramics with lower sintering temperature, suggesting that the BCTS–xMn material system is a promising candidate for lead-free piezoelectric ceramics. 相似文献
2.
S. G. Pawar S. L. Patil M. A. Chougule D. M. Jundale V. B. Patil 《Journal of Materials Science: Materials in Electronics》2011,22(3):260-264
Nanocrystalline thin films of TiO2 have been synthesized by sol gel spin coating technique Thin films of TiO2 annealed at 700 °C were characterized by X-ray diffraction(XRD), Atomic Force Microscopy, High resolution TEM and Scanning Electron Microscopy (SEM), The XRD shows formation of tetragonal anatase and rutile phases with lattice parameters a = 3.7837 Å and c = 9.5087 Å. The surface morphology of the TiO2 films showed that the nanoparticles are fine with an average grain size of about 60 nm. Optical studies revealed a high absorption coefficient (104 cm?1) with a direct band gap of 3.24 eV. The films are of the n type conduction with room temperature electrical conductivity of 10?6 (Ω cm)?1. 相似文献
3.
Muhammad Qadeer Awan Javed Ahmad Lasse Norén Teng Lu Yun Liu 《Journal of Materials Science: Materials in Electronics》2018,29(9):7142-7151
The effect of BiErO3 (BE) as a doping material on the structural, dielectric and ferroelectric properties of (KNa)NbO3 ceramics was explored in this research. Co-existence of two phase regions was confirmed in the composition range at x?=?0.5% and x?=?1.0%. The addition of BE content led to a decrease of the grain size and the ceramics became denser. Bulk P–E hysteresis loops were obtained with a maximum polarization of P max = 30.56 µC/cm2 and a remnant polarization of P r = 25.10 µC/cm2, along with a coercive field of E c ~ 11.26 kV/cm. The results revealed that a field strain value of ~?0.26 for x?=?0.5% of BE substitution was attained. This presents outstanding piezoelectric and dielectric properties. 相似文献
4.
Moti Ram 《Journal of Materials Science: Materials in Electronics》2011,22(4):426-429
Solution-based chemical method has been used to produce LiCo3/5Mn1/5Cu1/5VO4 ceramics. The formation of the compound is checked by X-ray diffraction analysis and it reveals an orthorhombic unit cell structure with lattice parameters of a = 9.8262 Å, b = 3.0706 Å, c = 14.0789 Å. Field emission scanning electron micrograph indicates a polycrystalline texture of the material with grains of unequal sizes (~0.2 to 3 μm). Complex impedance spectroscopy technique is used to study the dielectric properties. Temperature dependence of dielectric constant (ε r) at various frequencies exhibits the dielectric anomalies in ε r at T c (transition temperature) = 245, 255, 260 and 265 °C with (εr)max. ~458, 311, 214 and 139 for 50, 100, 200 and 500 kHz, respectively. Frequency dependence of tangent loss at various temperatures shows the presence of dielectric relaxation in the material. 相似文献
5.
Yih-Chien Chen Yen-Nien Wang Ruei-Yang Syu 《Journal of Materials Science: Materials in Electronics》2016,27(5):4259-4264
The microwave dielectric properties of Ba2MgWO6 ceramics were investigated with a view to the use of such ceramics in mobile communication. Ba2MgWO6 ceramics were prepared using the conventional solid-state method with various sintering temperatures. Dielectric constants (? r ) of 16.8–18.2 and unloaded quality factor (Q u × f) of 7000–118,200 GHz were obtained at sintering temperatures in the range 1450–1650 °C for 2 h. A maximum apparent density of 6.76 g/cm3 was obtained for Ba2MgWO6 ceramic, sintered at 1650 °C for 2 h. A dielectric constant (? r ) of 18.4, an unloaded quality factor (Q u × f) of 118,200 GHz, and a temperature coefficient of resonant frequency (τ f ) of ?34 ppm/°C were obtained when Ba2MgWO6 ceramics were sintered at 1650 °C for 2 h. 相似文献
6.
Konapala Sambasiva Rao Prayaga Murali Krishna Dasari Madhava Prasad D. Gangadharudu 《Journal of Materials Science》2007,42(13):4801-4809
The modulus Spectroscopy of Lead Potassium Titanium Niobate (Pb0.95K0.1Ti0.25Nb1.8O6, PKTN) Ceramics was investigated in the frequency range from 45 Hz to 5 MHz and the temperature, from 30 to 600 °C. XRD analysis in PKTN indicated a orthorhombic structure with lattice parameters a = 18.0809 Å, b = 18.1909 Å and c = 3.6002 Å. The dielectric anomaly with a peak was observed at 510 °C. Variation of εI and εII with frequency at different temperatures exhibit high values, which reflects the effect of space charge polarization and/or conduction ion motion. The electrical relaxation in ionically conducting PKTN ceramic analyzed in terms of Impedance and Modulus formalism. The Cole–Cole plots of impedance were drawn at different temperatures. The dielectric modulus, which describes the dielectric relaxation behaviour is fitted to the Kohlrausch exponential function. Near the phase transition temperature, a stretched exponential parameter β indicating the degree of distribution of the relaxation time has a small value. From the AC conductivity measurements the activation energy near phase transition temperature (T C°C) has been found to different from that of the above and below T C. The temperature dependence of electrical modulus has been studied and results are discussed. 相似文献
7.
Lei Yu Jigong Hao Zhijun Xu Wei Li Ruiqing Chu 《Journal of Materials Science: Materials in Electronics》2017,28(8):5840-5845
Novel green-emitting piezoelectric ceramics of SrBi4?x Er x Ti4O15 (SBT-xEr) were prepared. Strong up-conversion with bright green (524 and 548 nm) and a relatively weak red (660 nm) emission bands were obtained under 980 nm excitation at room temperature, which is attributed to the intra 4f–4f electronic transition of (2H11/2, 4S3/2)–4I15/2 and the transition from 4F9/2 to 4I15/2 of Er3+ ions, respectively. Simultaneously, Er3+ doping promotes the electrical properties. At 0.8 mol%Er, the optimal electric properties with high Curie temperature of T c?~527?°C, large remanent polarization of 2P r?~14.92 μC/cm2 and piezoelectric constant of d 33?~17 pC/N was achieved. As a multifunctional material, Er3+ doped SBT showed a great potential to be used in 3D-display, bio-imaging, solid state laser and optical temperature sensor. 相似文献
8.
Thermal deformations of Na6(UO2)2O(MoO4)4 were studied by high-temperature powder X-ray diffraction. The compound crystallizes in the triclinic system, space group Р\(\bar 1\), a = 7.636(7), b = 8.163(6), c = 8.746(4) Å, α = 72.32(9)°, β = 79.36(4)°, γ = 65.79(5)°, V = 472.74(4) Å3. It is stable in the temperature interval 20–700°С. The thermal expansion coefficients (TECs) are α11 = 25.5 × 10–6, α22 = 7.8 × 10–6, and α33 = 1.1 × 10–6 (°C)–1. The orientation of the TEC pattern relative to the crystallographic axes is a33^Z = 45°, a33^X = 122°, a22^Z = 59°, and a22^X = 66°. The anisotropy of the thermal expansion is due to specific features of the crystal structure of the compound. 相似文献
9.
Xiong Zhang Hongjia Song Congbing Tan Shengsheng Yang Yuxiong Xue Jinbin Wang Xiangli Zhong 《Journal of Materials Science》2017,52(24):13879-13885
In this paper, the epitaxial hexagonal LuFeO3 (h-LuFeO3) thin films with c-axis-oriented single phase, smooth surface were grown on YSZ (111) substrates by pulsed laser deposition method. Furthermore, a structural distortion of increased lattice constant of c is found in the epitaxial h-LuFeO3 thin films. Moreover, the epitaxial h-LuFeO3 thin films show room-temperature ferromagnetism. The coercive field and remnant magnetization of the epitaxial h-LuFeO3 thin film decrease with the increase in the test temperature from 50 to 300 K. The study would be of benefit to the room-temperature single-phase multiferroic materials. 相似文献
10.
We report the results of magnetic, magnetocaloric properties, and critical behavior investigation of the double-layered perovskite manganite La1.4(Sr0.95Ca0.05)1.6Mn2O7. The compounds exhibits a paramagnetic (PM) to ferromagnetic (FM) transition at the Curie temperature T C = 248 K, a Neel transition at T N = 180 K, and a spin glass behavior below 150 K. To probe the magnetic interactions responsible for the magnetic transitions, we performed a critical exponent analysis in the vicinity of the FM–PM transition range. Magnetic entropy change (??S M) was estimated from isothermal magnetization data. The critical exponents β and γ, determined by analyzing the Arrott plots, are found to be T C = 248 K, β = 0.594, γ = 1.048, and δ = 2.764. These values for the critical exponents are close to the mean-field values. In order to estimate the spontaneous magnetization M S(T) at a given temperature, we use a process based on the analysis, in the mean-field theory, of the magnetic entropy change (??S M) versus the magnetization data. An excellent agreement is found between the spontaneous magnetization determined from the entropy change [(??S M) vs. M 2] and the classical extrapolation from the Arrott curves (µ0H/M vs. M 2), thus confirming that the magnetic entropy is a valid approach to estimate the spontaneous magnetization in this system and in other compounds as well. 相似文献
11.
Biao Dong Hua Yang Yuming Cui Lianxiang Yu Shouhua Feng 《Journal of Materials Science》2007,42(9):3167-3171
BiY2Cr x Fe5?x O12 (x = 0, 0.05, 0.1, 0.2, 0.3) nanocrystals were synthesized by using a sol-gel method. Samples were characterized by the powder X-ray diffraction (XRD), the thermal gravity analysis (TGA) and the differential thermal analysis (DTA), the vibrating sample magnetometer(VSM) and Mössbauer spectrums. The average sizes of the particles were determined by the Scherrer’s formula. The special Ms and Mössbauer spectra of BiY2Cr x Fe5?x O12 nanocrystals are researched at room temperature. It is seen that the special Mss of samples are initially increased with increasing Cr3+ content (x < 0.1), and decreased with increasing content of Cr3+ ions (x > 0.1). 相似文献
12.
X-ray diffraction data are presented for combustion products in the Al-W-N system. New, nonequilibrium intermetallic compounds have been identified, their diffraction patterns have been indexed, and their unit-cell parameters have been determined. The phases α-and β-WAl4 are shown to exist in three isomorphous forms, differing in unit-cell centering. The phases α′-, α″-, and α?-WAl4 are monoclinic, with a 0 = 5.272 Å, b 0 = 17.770 Å, c 0 = 5.218 Å, β = 100.10°; point groups C12/c1, A12/n1, I12/a1, respectively. The phases β′-, β″-, and β?-WAl4 are monoclinic, with a 0 = 5.465 Å, b 0 = 12.814 Å, c 0 = 5.428 Å, β = 105.92°; point groups A112/m, B112/m, I112/m, respectively. The compounds WAl2 and W3Al7, identified each in two isomorphous forms, differ in cell metrics (doubling) but possess the same point group: P222. WAl 2 ′ : orthorhombic, a 0 = 5.793 Å, b 0 = 3.740 Å, c 0 = 6.852 Å. WAl 2 ″ : orthorhombic, a 0 = 11.586 Å, b 0 = 3.740 Å, c 0 = 6.852 Å. W3Al 7 ′ : orthorhombic, Pmm2, a 0 = 6.225 Å, b 0 = 4.806 Å, c 0 = 4.437 Å. W3Al 7 ″ : orthorhombic, Pmm2, a 0 = 12.500 Å, b 0 = 4.806 Å, c 0 = 8.874 Å. The new phase WAl3: triclinic, P1, a 0 = 8.642 Å, b 0 = 10.872 Å, c 0 = 5.478 Å, α = 104.02°, β = 64.90°, γ = 107.15°. 相似文献
13.
Zi-de Yu Xiao-ming Chen Han-li Lian Qian Zhang Wen-xin Wu 《Journal of Materials Science: Materials in Electronics》2018,29(22):19043-19051
Pure K0.5Na0.5NbO3 lead-free piezoelectric ceramics without any dopants/additives were sintered at various temperatures (950–1125 °C) in low pO2 atmosphere (pO2?~?10?6 atm). All ceramics exhibit high relative densities (>?94%) and low weight loss (<?0.6%). Compared to the ceramics sintered in air, the ceramics sintered in low pO2 exhibit improved electrical properties. The piezoelectric constant d33 and converse piezoelectric constant d33* are 112 pC/N and 119 pm/V, respectively. The ceramics show typical ferroelectric behavior with the remnant polarization of 21.6 µC/cm2 and coercive field of 15.5 kV/cm under measurement electric field of 70 kV/cm. The good electrical properties of the present samples are related to the suppression of volatility of the alkali cations during the sintering process in low pO2 atmosphere. 相似文献
14.
Peng Zhou Zhiheng Mei Chao Yang Yajun Qi Kun Liang Zhijun Ma Tianjin Zhang 《Journal of Materials Science: Materials in Electronics》2016,27(8):7755-7759
The scaling behavior of dynamic hysteresis was investigated in Bi3.15Nd0.85Ti3O12 bulk ceramics at a frequency of 1–1000 Hz and an external electric field amplitude of 79–221 kV/cm. The scaling behavior at low amplitude (E 0 ≤ 114 kV/cm) takes the form of \(\langle A \rangle \propto f^{ - 0.013} E_{0}^{0.7}\) for low frequency (f ≤ 200 Hz) and \(\langle A \rangle \propto f^{ - 0.013} E_{0}^{0.22}\) for high frequency (f > 200 Hz), where \(\langle A \rangle\) is the area of hysteresis loop and f and E 0 are frequency and amplitude of external electric field, respectively. At high amplitude (E 0 > 114 kV/cm), we obtain \(\langle A \rangle \propto f^{0.011} E_{0}^{1.163}\) at low frequency and \(\langle A \rangle \propto f^{ - 0.015} E_{0}^{0.7}\) at high frequency. At low E 0, the contribution to the scaling relation mainly results from reversible domain switching, while at high E 0 reversible and irreversible domain switching concurrently contribute to the scaling relation. 相似文献
15.
Ekaphan Swatsitang Krissana Prompa Thanin Putjuso 《Journal of Materials Science: Materials in Electronics》2018,29(15):12639-12651
In this work, the nominal CaCu3?xMgxTi4.2O12 (0.00, 0.05 and 0.10) ceramics were prepared by sintering pellets of their precursor powders obtained by a polymer pyrolysis solution method at 1100 °C for different sintering time of 8 and 12 h. Very low loss tangent (tanδ)?<?0.009–0.014 and giant dielectric constant (ε′) ~?1.1?×?104–1.8?×?104 with excellent temperature coefficient (Δε′) less than ±?15% in a temperature range of ??60 to 210 °C were achieved. These excellent performances suggested a potent application of the ceramics for high temperature X8R and X9R capacitors. It was found that tanδ values decreased with increasing Mg2+ dopants due to the increase of grain boundary resistance (Rgb) caused by the very high density of grain, resulting from the substitution of small ionic radius Mg2+ dopants in the structure. In addition, CaCu3?xMgxTi4.2O12 ceramics displayed non-linear characteristics with the significant enhancements of a non-linear coefficient (α) and a breakdown field (Eb) due to Mg2+doping. The high values of ε′ (14012), α (13.64) and Eb (5977.02 V/cm) with very low tanδ value (0.009) were obtained in a CaCu2.90Mg0.10Ti4.2O12 ceramic sintered at 1100 °C for 8 h. 相似文献
16.
The crystal structure of a previously unknown compound [CH3NH3][(UO2)(H2AsO4)3] was solved by direct methods and refined to R 1 = 0.038 for 3041 reflections with |F hkl | >-4σ |F hkl |. The compound crystallizes in the monoclinic system, space group P21/c, a = 8.980(1), b = 21.767(2), c = 7.867(1) Å, β = 115.919(5)°, V = 1383.1(3) Å3, Z = 4. In the structure of the compound, pentagonal bipyramids of uranyl ions, sharing bridging atoms with tetrahedral [H2AsO4]? anions, form strongly corrugated layered complexes [(UO2)(H2AsO4)3]? arranged parallel to the (100) plane. The protonated methylamine molecules [CH3NH3]+ form unidimensional tapelike packings parallel to the c axis and linked by hydrophilic-hydro-phobic interactions. The topology of the layered uranyl arsenate complex [(UO2)(H2AsO4)3]? is unusual for uranyl compounds and was not observed previously. A specific feature of this topology is the presence of monodentate arsenate “branches” arranged within the layer. 相似文献
17.
Huanfu Zhou Wendong Sun Jin Huang Kangguo Wang Xiuli Chen Xiaobin Liu Hong Ruan 《Journal of Materials Science: Materials in Electronics》2018,29(8):6232-6235
In the present work, a novel MgAl2Ti3O10 ceramic was obtained using a traditional solid-state reaction method. X-ray diffraction and energy dispersive spectrometer showed that the main MgAl2Ti3O10 phase was formed after sintered at 1300–1450 °C. With rising the sintering temperature from 1300 to 1450 °C, the bulk density (ρ), relative permittivity (ε r ) and Q?×?f value firstly increased, reached the maximum values (3.61 g/cm3, 14.9, and 26,450 GHz) and then decreased. The temperature coefficient of resonator frequency (τ f ) showed a slight change at a negative range of ??94.6 to ??83.7 ppm/°C. When the sintering temperature was 1400 °C, MgAl2Ti3O10 ceramics exhibited the best microwave dielectric properties with Q?×?f?=?26,450 GHz, ε r ?=?14.9 and τ f ?=???83.7 ppm/°C. 相似文献
18.
This study reports the effect of coronene (C24H12) addition on some superconducting properties such as critical temperature (Tc), critical current density (Jc), flux pinning force density (Fp), irreversibility field (Hirr), upper critical magnetic field (Hc2), and activation energy (U0), of bulk MgB2 superconductor by means of magnetisation and magnetoresistivity measurements. Disk-shaped polycrystalline MgB2 samples with varying C24H12 contents of 0, 2, 4, 6, 8, 10 wt%, were produced at 850 °C in Ar atmosphere. The obtained results show an increase in field-Jc values at 10 and 20 K resulting from the strengthened flux pinning, and a decrease in critical temperature (Tc) because of C substitution into MgB2 lattice, with increasing amount of C24H12 powder. The Hc2(0) and Hirr(0) values are respectively found as 144, 181, 172 kOe, and 128, 161, 145 kOe for pure, 4 wt% and 10 wt% C24H12 added samples. The U0 depending on the magnetic field curves were plotted using thermally activated flux flow model. The maximum U0 values are respectively obtained as 0.20, 0.23 and 0.12 eV at 30 kOe for pure, 4 wt% and 10 wt% C24H12 added samples. As a result, the superconducting properties of bulk MgB2 at high fields was improved using C24H12, active carbon source addition, because of the presence of uniformly dispersed C particles with nanometer order of magnitude, and acting as effective pinning centres in MgB2 structure. 相似文献
19.
D. C. Huang Q. L. Liu W. Zhang J. Ding J. J. Gu S. M. Zhu Q. X. Guo D. Zhang 《Journal of Materials Science》2011,46(15):5064-5070
An activated carbon (AC) with high-porosity was prepared from Zizania latifolia leaves by a one-step method combining chemical and physical activation. K2CO3 was employed as a chemical reagent, and air as a physical agent. During the activation, several key parameters were discussed, including the effects of activation temperature, K2CO3 impregnation ratio, amount of introduced air on the surface area and pore volumes evolution of the ACs derived from the Zizania latifolia leaves. The synergistic effect between the chemical agent and the physical agent was also investigated. Under optimal activation conditions, the as-synthesized AC attained a maximum surface area up to 2481 m2/g, with 1.21 cm3/g pore volume, and it had a micro/meso porosity developed by the combining activation. The crystal sizes of the as-synthesized AC along the a- and c-axes were about 5 nm and 1–2 nm, respectively. The average thickness of the crystallites is 3–4 layers with about 0.37 nm interlayer spacing. 相似文献
20.
Aysegul Kahraman 《Journal of Materials Science: Materials in Electronics》2018,29(10):7993-8001
The purpose of this study is to understand the effects of substrate temperature (ST) and post deposition annealing (PDA) on the structural-electrical properties of Gd2O3 film and to evaluate the electrical performances of the MOS based devices formed with this dielectric. The Gd2O3/Si structures were annealed at 500, 600, 700, and 800 °C under N2 ambient after the films were grown on heated p-Si substrate at various temperatures ranged from 20 to 300 °C by RF magnetron sputtering. For any given ST, the crystallization/grain size increased with increasing PDA temperature. The bump in the accumulation region or continuous decrease in the capacitance values of the inversion region of the C–V curves for 800 °C PDA was not observed. The lowest effective oxide charge density (Q eff ) value was obtained to be ??1.13?×?1011 cm?2 from the MOS capacitor with Gd2O3, which is grown on heated Si at 300 °C and annealed at 800 °C. The density of the interface states (D it ) was found to be in the range of 0.84?×?1011 to 1.50?×?1011 eV?1 cm?2. The highest dielectric constant (ε) and barrier height \(({\Phi _B})\) values were found to be 14.46 and 3.68, which are obtained for 20 °C ST and 800 °C PDA. The results show that the negative charge trapping in the oxide layer is generally more than that of the positive, but, it is reverse of this situation at the interface. The leakage current density decreased after 20 °C ST, but no significant change was observed for other ST values. 相似文献