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1.
Haowei Lu Lizhu Liu Jiaqi Lin Wenlong Yang Ling Weng Xiaorui Zhang 《Ceramics International》2018,44(6):6514-6519
The ceramic thin films of 47(Ba0.7Ca0.3)TiO3–0.53Ba(Zr0.2Ti0.8)O3 (BCZT) + x (x = 0.2, 0.3, 0.4 and 0.5) mol% Tb were grown on Pt(111)/Si substrates with various annealing temperature by pulsed laser deposition. The XRD spectra confirm that Tb element can enhance the (l10) and (111) orientations in ceramic films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images show that Tb-doping can increase particle size effectively. The surface of Tb-doped film annealed at 800 ℃ is uniform and crack-free, and the average particle size and mean square roughness (RMS) are about 280 nm and 4.4 nm, respectively. Comparing with pure BCZT, the residual polarization (Pr) of 0.4 mol% Tb-doped film annealed at 800 ℃ increase from 3.6 to 9.8 μC/cm2. Moreover, the leakage current density value of Tb doped films are one order of magnitude (5.33 × 10?9?1.97 × 10?8 A/cm2 under 100 kV/cm) smaller than those of pure BCZT films (1.02 × 10?7 A/cm2). 相似文献
2.
Hongyu Yang Enzhu Li Yingfeng Yang Yan Shi Hongcai He Shuren Zhang 《Ceramics International》2018,44(5):5010-5016
Low-firing (Zn0.9Mg0.1)1?xCoxTiO3 (x = 0.02–0.10) (ZMCxT) microwave dielectric ceramics with high temperature stability were synthesized via conventional solid-state reaction. The influences of Co2O3 substitution on the phase composition, microstructure and microwave dielectric properties of ZMCxT ceramics were discussed. Rietveld refinement results show the coexistence of ZnTiO3 and ZnB2O4 phases at x = 0.02–0.10. (Zn0.9Mg0.1)1?xCoxTiO3 ceramic with x = 0.06 (ZMC0.06T) obtains the best combination microwave dielectric properties of: εr = 21.58, Q × f = 53,948 GHz, τf = ? 54.38 ppm/°C. For expanding its application in LTCC field, 3 wt% ZnO-B2O3-SiO2 (ZBS) and 9 wt% TiO2 was added into ZMC0.06T ceramic, great microwave dielectric properties were achieved at 900 °C for 4 h: εr = 26.03, Q × f = 34,830 GHz, τf = ? 4 ppm/°C, making the composite ceramic a promising candidate for LTCC industry. 相似文献
3.
Xiao Wu Cengceng Fang Jinfeng Lin Chunwen Liu Laihui Luo Mei Lin Xinghua Zheng Cong Lin 《Ceramics International》2018,44(5):4908-4914
The lead-free Er3+-doped (K0.48Na0.48Li0.04)(Nb0.96Bi0.04)O3 (KNLNB-Er-x) ceramics were fabricated by conventional pressureless sintering. They possess a tetragonal perovskite phase with dense microstructure. High transmittances of the ceramics are obtained both in the visible and infrared regions. The optical band gap energies of them are 3.07–3.11 eV, close to other KNN-based materials. The relaxor-like characteristics, good dielectric, ferroelectric and piezoelectric properties of the ceramics have been obtained. The up-conversion photoluminescence spectra have been studied and obvious color-tunable emissions have been observed by modulating temperature. The fluorescence intensity ratio (FIR) value based on green emissions at 533 and 555 nm in the temperature ranging from 300 to 750 K have been investigated, giving the maximum sensitivity of ~ 0.0038 K?1. Furthermore, the FIR technique opens up a method to detect the Curie temperature of the ceramics. Owing to both optical and electrical properties, the KNLNB-Er-x transparent ceramics could be a promising candidate in the application of color-tunable solid-state lightings, optical temperature sensors, and electrical-optical coupling devices. 相似文献
4.
Yuan Yao Yong Li Ningning Sun Jinhua Du Xiaowei Li Liwen Zhang Qiwei Zhang Xihong Hao 《Ceramics International》2018,44(6):5961-5966
[0.9(0.94Na0.5Bi0.5TiO3?0.06BaTiO3)?0.1NaNbO3]-xZnO (NBT-BT-NN-xZnO, x=0, 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt%) ferroelectric ceramics were fabricated using a conventional solid-state reaction method. The effects of ZnO content on dielectric, energy-storage and discharge properties were systematically investigated. Dielectric constant and difference between maximum and remanent polarization were significantly improved by ZnO doping. Dielectric constant of NBT-BT-NN-1.0-wt% ZnO was 3218 at 1 kHz and room temperature, i.e. one time bigger than that of pure NBT-BT-NN ceramic. As a consequence, a maximum energy-storage density of 1.27 J/cm3 with a corresponding efficiency of 67% was obtained in NBT-BT-NN-1.0-wt% ZnO ceramic. Moreover, its pulsed discharge energy density was 1.17 J/cm3, and 90% of which could be released in less than 300 ns. Therefore, ZnO doped NBT-BT-NN ceramic with a large energy-storage density and short release time could be a potential candidate for applications in high energy-storage capacitors. 相似文献
5.
《Journal of the European Ceramic Society》2014,34(5):1439-1444
(Ba0.85Ca0.15)1−xPrx(Zr0.1Ti0.9)O3 (where 0 < x < 0.01, abbreviated as BCZT:xPr) ceramics were fabricated by conventional solid-state reaction method. The influence of dopant concentration and microstructure on photoluminescence, ferroelectric, and piezoelectric properties was systematically investigated. The results showed that the photoluminescence spectra of the samples exhibited strong green (530 nm) and red (602 nm) emissions upon excitation of the 430 nm to 500 nm light, which couples well with to the emission band of the commercial blue light-emitting diodes chips. The emission intensities were strongly dependent on the dopant concentration and crystallite size, which reached the optimal value when the crystallite size and dopant concentration were 8 μm and 0.002 mol, respectively. Meanwhile, a large piezoelectric response with d33 = 325 pC/N was obtained for BCZT:0.002Pr near the morphotropic phase boundary. Therefore, the Pr-doped BCZT materials, simultaneously exhibiting excellent luminescent properties and high piezoelectric properties, may have significant technological promise in novel multifunctional devices. 相似文献
6.
Li2CO3 has been used as a sintering aid for fabricating lead-free ferroelectric ceramic 0.93(Bi0.5Na0.5TiO3)-0.07BaTiO3. A small amount (0.5 wt%) of it can effectively lower the sintering temperature of the ceramic from 1200 °C to 980 °C. Unlike other low temperature-sintered ferroelectric ceramics, the ceramic retains its good dielectric and piezoelectric properties, giving a high dielectric constant (1570), low dielectric loss (4.8%) and large piezoelectric coefficient (180 pC/N). The “depolarization” temperature is also increased to 100 °C and the thermal stability of piezoelectricity is improved. Our results reveal that oxygen vacancies generated from the diffusion of the sintering aid into the lattices are crucial for realizing the low temperature sintering. Owing to the low sintering temperature and good dielectric and piezoelectric properties, the ceramics, especially of multilayered structure, should have great potential for practical applications. 相似文献
7.
Nianshun Zhao Huiqing Fan Xiaohu Ren Shang Gao Jiangwei Ma Yungui Shi 《Ceramics International》2018,44(1):571-579
Novel ((Bi0.5Na0.5)0.94Ba0.06)1-x(K0.5Nd0.5)xTiO3(x = 0.0, 0.02, 0.04, 0.06) lead-free ceramics (BNBT–xKN) were prepared by the solid-state reaction method. The effects of A-site (K0.5Nd0.5)2+ complex-ion substitution on their phase structure, dielectric, piezoelectric, and electromechanical properties were studied. The X-ray diffraction results indicate that all compositions are located in the morphotropic phase boundary (MPB) region where the tetragonal phase coexists with the rhombohedral phase. In addition, as the KN content increases, the ferroelectric order transform to relaxor order, which is characterized by a degeneration of maximum polarization, remnant polarization and correspondingly adjusts the ferroelectric-relaxor transformation temperature (TF-R) to room temperature. Interestingly, the disruption of ferroelectric phase caused a significant improvement of strains. A maximum strain of ~ 0.52% corresponding to normalized strain of ~ 612 pm/V appeared at 85 kv/cm for the x = 0.04 composition. Particularly, the composition of x = 0.04 exhibited high electrostrains of temperature insensitivity, which remained above 0.4% and kept within 10% from ambient temperature up to 110 °C. It can be ascribed to the coexistence of non-ergodic and ergodic states in the relaxor region. As a result, the systematic investigations on the BNBT–xKN ceramics can benefit the developments of temperature-insensitive “on-off” actuators. 相似文献
8.
(Ba1?xRx)(Ti1?xHox)O3 (R = La, Pr, Nd, Sm; x ≥ 0.04) (BRTH) ceramics were prepared using a mixed oxides method. The solubility limits in BRTH with R = La, Pr, Nd, Sm were determined by XRD to be x = 0.11, 0.12, 0.06, and 0.14, respectively. The ionic radius of R at Ti-site plays a decisive role in the solubility limit in BRTH. Only BRTH with R = La satisfied Vegard's law. The multiplicity of photoluminescence (PL) signals of Nd3+/Ho3+ and Sm3+/Ho3+ in Raman scattering under 532-nm excitation laser and the high-permittivity abnormality for the denser BRTH with R = Sm and at x = 0.07 were reported. The PL provided the evidence of a small number of Ho3+ at Ba-site in BRTH and it was determined that the number of Ba-site Ho3+ ions increased from 0.05 at% at R = La to 0.19 at% at R = Sm with increasing atomic number of light rare earth. BRTH exhibited a much broadened dielectric-temperature characteristics, marked by ×5 T, ×6 T, ×7 T, and ×8 S dielectric specifications for BRTH with R = La, Pr, Nd, Sm and at x = 0.06, respectively, and they exhibited lower dielectric loss (tan δ < 0.015) at room temperature. The dielectric-peak temperature (Tm) of BRTH decreased linearly at a rate of less than ?21 °C/%(R/Ho). The defect chemistry, solubility limit, lower dielectric loss, and dielectric abnormality are discussed. 相似文献
9.
The influence of CuO and B2O3 addition on the sintering behavior, microstructure and microwave dielectric properties of Ti1?xCux/3Nb2x/3O2 (TCN, x = 0.23) ceramic have been investigated. It was found that the addition of CuO and B2O3 successfully reduced the sintering temperature of TCN ceramics from 950 to 875 °C. X-ray diffraction studies showed that addition of CuO-B2O3 has no effect on the phase composition. The TCN ceramics with 0.5 wt% CuO-B2O3 addition showed a high dielectric constant of 95.63, τf value of + 329 ppm/°C and a good Q × f value of 8700 GHz after sintered at 875 °C for 5 h, cofirable with silver electrode. 相似文献
10.
S. Abou Dargham F. Ponchel N. Abboud M. Soueidan A. Ferri R. Desfeux J. Assaad D. Remiens D. Zaouk 《Journal of the European Ceramic Society》2018,38(4):1450-1455
Lead-free Bi0.5Na0.5TiO3 (BNT) piezoelectric thin films were deposited on Pt/TiOx/SiO2/Si substrates by Sol-Gel method. A dense and well crystallized thin film with a perovskite phase was obtained by annealing the film at 700 °C in a rapid thermal processing system. The relative dielectric constant and loss tangent at 12 kHz, of BNT thin film with 350 nm thickness, were 425 and 0.07, respectively. Ferroelectric hysteresis measurements indicated a remnant polarization value of 9 μC/cm2 and a coercive field of 90 kV/cm. Piezoelectric measurements at the macroscopic level were also performed: a piezoelectric coefficient (d33effmax) of 47 pm/V at E = 190 kV/cm was obtained. The piezoresponse force microscopy data confirmed that BNT thin films present ferroelectric and piezoelectric behavior at the nanoscale level. 相似文献
11.
Meng Shen Shenglin Jiang Mingyu Li Yang Liu Huan Liu Pin Liu Baoyan Fan Shiyong Qiu Guangzu Zhang Qing Wang 《Ceramics International》2018,44(1):193-200
Free-standing Pb0.85La0.1(Zr0.65Ti0.35)O3 (PLZT) ceramic thick films have been prepared via a facile and low-cost self-separating screen printing method for electrocaloric cooling, and the relation among the fabrication processes, phase composition, microstructure, dielectric characteristics, ferroelectric properties and electrocaloric effect (ECE) has been systematically investigated. Compared to the conventional ceramic thick films supported by substrates, the free-standing feature enables the EC cooling of the free-standing PLZT thick films to be fully used for cooling down different thermal loads rather than be futilely absorbed by the substrates. Furthermore, without the mechanical restriction of the substrates, the free-standing PLZT thick films can freely shrink during the high-temperature densification process, leading to their high density and favorable microstructures. Additionally, by introducing an adequate amount of excess PbO, the pyrochlore phase can be removed from the samples to yield high-purity perovskite PLZTs. With the comprehensive improvement in phase composition, microstructure and the elimination of mechanical strain between the active materials and substrates, the free-standing PLZT thick films exhibited an optimized ECE including changes of temperature and entropy of 1.95 °C and 2.09 J kg?1 K?1, which are almost 3 times that of the samples deposited on the Al2O3 substrates without excess PbO. This work would contribute to the development of ferroelectric ceramics, especially thick films, for practical EC cooling. 相似文献
12.
Xiaoguo Song Yixuan Zhao Shengpeng Hu Jian Cao Wei Fu Jicai Feng 《Ceramics International》2018,44(5):4622-4629
The effect of Ti content on the wettability of AgCu-Ti filler on porous Si3N4 ceramic was studied by the sessile drop method. AgCu-2 wt% Ti filler alloy showed a minimum contact angle of 14.6° on porous Si3N4 ceramic during the isothermal wetting process. The mechanism of AgCu-Ti filler wetting on porous Si3N4 ceramic is clarified in this paper. Porous Si3N4 ceramic was brazed to TiAl alloy using AgCu-xTi (x = 0, 2 wt%, 4 wt%, 6 wt%, 8 wt%) filler alloy at 880 °C for 10 min. The effect of Ti content on the interfacial microstructure and mechanical properties of porous-Si3N4/AgCu-xTi/TiAl joints are studied. The typical interfacial microstructure of p-Si3N4/AgCu-Ti/TiAl joint is p-Si3N4/penetration layer (Ag(s,s)+Si3N4+TiN+Ti5Si3)/Ag(s,s)+Cu(s,s)+TiCu/AlCu2Ti/TiAl. The maximum shearing strength of the brazed joint was 14.17 MPa and fracture that occurred during the shearing test propagated in the porous Si3N4 ceramic substrate for the formation of the penetration layer. 相似文献
13.
Recently, lanthanide niobates have attracted significant attentions in multi-functional materials. Herein a series of fergusonite structure-related (1-x)NdNbO4-xLnNbO4 (Ln = Yb, Er, Ho, Dy, Gd and Ce; 0.02 ≤ x ≤ 0.08) ceramics were prepared via conventional solid-state reaction method and the microwave dielectric properties were systematically discussed. The X-ray diffraction, Raman spectra were employed to investigate the crystal structure. Obtained results indicate that the ceramic samples present single monoclinic phase belong to the space group of I2/a. Microwave dielectric behaviors shown that the permittivity (εr) and the quality factor (Q × f) were influenced by the relative density, and the temperature coefficients of resonant frequency (τ?) value kept the same variation tendency with the Nb-site bond valence. Furthermore, Far-IR and bond energy study evidenced the Ln-O oscillations dominated the main dielectric polarization and system stability. Good microwave dielectric properties, with εr ~ 20.88, Q × f ~ 66,510 GHz (at 8.60 GHz) and τf ~ ? 36.59 ppm/°C, were obtained in 0.94NdNbO4–0.06YbNbO4 ceramics when sintered at 1250 °C for 4 h. The (Nd0.94Yb0.06)NbO4 might be potential candidate for the applications of modern microwave devices. 相似文献
14.
Qianyu Guo Lingxia Li Shihui Yu Zheng Sun Haoran Zheng Jiangteng Li Weijia Luo 《Ceramics International》2018,44(1):333-338
Temperature–stable dielectrics based on Cu–doped Bi2Mg2/3Nb4/3O7 pyrochlore ceramics were prepared by conventional solid–state reaction. Microstructure analysis indicates that all of the specimen maintain the cubic pyrochlore phase, a fluorite–like phase of Bi3NbO7 and a Bi5Nb3O15 formed for Cu doping. The dielectric constant is dominated by densification of samples and secondary phases, while the dielectric loss is related by the secondary phases, grain boundaries, and leakage current characteristics. The (1-x)BMN - xCuO(x = 0.1 mol%) ceramic sintered at 925 °C shows excellent dielectric properties with dielectric constant of ~184.06, dielectric loss of ~0.0017 and near zero τε (?20 ppm/°C) is obtained at sintering temperature of 925 °C, which could be a promising candidate for LTCC. 相似文献
15.
Shilpi Chandel Preeti Thakur Shyam Singh Thakur Vivek Kanwar Monika Tomar Vinay Gupta Atul Thakur 《Ceramics International》2018,44(5):4711-4718
Pure BiFeO3 (BFO) and Al doped BFO samples were synthesized via citrate precursor method and sintered at 500 °C for two hours. Effect of Al doping on the structural, optical, electrical, dielectric and magnetic properties were investigated. X-ray diffraction (XRD) confirmed the distorted rhombohedral structure without any merging of peaks which indicates no structural transformation. Average crystallite size was found to be in the range 28–39 nm. Field emission scanning electron microscopy (FESEM) images illustrated the dense, agglomerated, spherically shaped with reduced grain size nanoparticles. Increased value of dielectric constant with low dielectric tangent loss was observed for the Al doped BFO samples. The value of dielectric constant was found to be 51 at 100 kHz for x = 0.1 sample. Temperature dependent dielectric constant showed a dielectric anomaly, indicating the antiferromagnetic transition. The remanent polarization and the corresponding coercive field for x = 0.1 was found to be 0.0625 µC/cm2 and 56.154 kV/cm at an operating voltage of 1000 V. The improved electrical properties with low leakage current density were ascribed to the stabilization of the pervoskite structure and reduced oxygen vacancies. 相似文献
16.
BaZr0.2Ti0.8O3 (BZT) relaxor ferroelectric (FE) films with tetragonal structure were deposited on Pt/TiO2/SiO2/Si(100) substrates via a sol-gel technique. A giant electrocaloric effect (ECE) was observed in the compact films with ΔT = 43.6 K and ΔS = 61.9 J/K kg at near room temperature of 366.5 K, which was attributed to the high breakdown electric field of E = 1010 kV/cm. Meanwhile, large negative ECE (ΔT = ? 5.2 K and ΔS = ? 8.8 J/K kg at room temperature of 305 K, ΔT = ? 5.1 K and ΔS = ? 7.2 J/K kg at near room temperature of 375 K) were achieved. The abnormal negative ECE is originated from structural transformation in relaxor ferroelectrics. The coexisting of giant negative and positive electrocaloric effects makes it more effective to realize the refrigeration during the application or removal of an electric field. The maximum electrocaloric coefficient (ζmax = 0.043 K cm/kV) and refrigeration efficiency (COP = 35.18) of the films were obtained at near room temperature of 366.5 K. The giant electroelectric effect makes BZT films promising as lead-free materials for application in environment-friendly refrigeration equipment at near room temperature. 相似文献
17.
Ke Yang Jingran Liu Bo Shen Jiwei Zhai Shujian Wang Jia Tian 《Ceramics International》2018,44(6):6181-6185
In this work, 25.6BaO-6.4K2O-32Nb2O5-36SiO2-xTiO2 (0 ≤ x ≤10 mol%) (BKNST) glass ceramics were synthesized by conventional melts and controllable crystallization method. The effects of different TiO2 addition on the phase composition, dielectric and energy storage properties of BKNS glass ceramics were systematically evaluated. With the TiO2 concentration increasing, a growing content of Ba2TiO4 phase was observed in the glass ceramics. The microstructures appeared to be homogenous and uniform with very low porosity through the addition of TiO2, for which the maximal breakdown strength of 2112 kV/cm and the corresponding energy storage density of 9.48 J/cm3 were obtained with x = 7.5. The extremely low dielectric loss of less than 1‰ (25 °C, 100 kHz) and the obviously improved microstructure contributed to the increased breakdown strength. In addition, the discharge power density of the glass-ceramic capacitor (x = 7.5) was investigated using the RLC charge-discharge circuit and a relatively high value of 16 MW/cm3 at 300 kV/cm was obtained. 相似文献
18.
Zaheer Abbas Gilani Muhammad Shahzad Shifa H.M. Noor ul Huda Khan Asghar Muhammad Azhar Khan Muhammad Naeem Anjum Muhammad Nauman Usmani Rajjab Ali Muhammad Farooq Warsi 《Ceramics International》2018,44(2):1881-1885
Praseodymium substituted nano crystalline LiCo spinel ferrites with different concentrations were fabricated by micro-emulsion route. TGA, X-ray diffraction and magnetic properties was employed to study the effect of substitution of the Pr on the structure and magnetic parameters. XRD confirmed the formation of the single phase spinel ferrites with minor coexistence of orthophase. The particle size from XRD data was calculated in range from 53 nm to 106 nm. The VSM was employed for magnetic studies between ? 10,000 Oe and 10,000 Oe range. Considerable high value of ‘Hc’ coercivity (1581 Oe) and an enhanced value of ‘Ms’ saturation magnetization (51 emu/g) have been obtained as result of substitution. The value of Hc is high enough value but in soft ferrite range. Hence synthesized LiCo0.5PrxFe2?xO4 ferrites are suitable for high density storage devices application. 相似文献
19.
Xiaokai Li Yangyang Xu Xiaojian Mao Qiangqiang Zhu Junxi Xie Minghui Feng Benxue Jiang Long Zhang 《Ceramics International》2018,44(2):1362-1369
Highly transparent ZrO2-doped Y2O3 ceramics were successfully synthesized using the hot isostatic pressing (HIP) process. The effects of the ZrO2 content on the sintering behaviors, optical transmission spectra, Vickers hardness, grain size, size distribution, and Raman spectra were determined. The results indicated that decreased ZrO2 content could promote increased transmittance, red-shifted infrared cutoff wavelength, increased thermal conductivity, decreased Vickers hardness, and increased lattice ordering. According to the optical transmission spectra, the optimized ZrO2 content was 0.50 at%, at which point the ceramic exhibited a larger pre-sintering temperature range of 1650–1750 °C and the average grain size of 3.35 µm at 1750 °C. The grain size was significantly decreased at lower pre-sintering temperatures. Furthermore, a moderate Vickers hardness of 8.42 GPa and high thermal conductivity of 10.85 W/m K at room temperature were obtained for the optimized ceramic. 相似文献
20.
Li3/8Sr7/16-3x/2LaxZr1/4Nb3/4O3 (x = 0, 0.05, 0.10, 0.15, 0.20) were synthesized using the conventional solid-state reaction method. In order to increase the vacancy concentration, La3+ was doped on the Sr2+ site. Crystal structures of doped samples were characterized by X-ray diffraction. Except, perovskite-type Li3/8Sr7/16-3x/2LaxZr1/4Nb3/4O3 (x = 0, 0.05, 0.10, 0.15) samples were fabricated by heat treatment at 1250 °C, 1275 °C, 1275 °C and 1275 °C, respectively, for 15 h. Lattice sizes decreased with the increase of doping amounts because of the smaller ion radius of La3+ compared to that of Sr2+. Ionic conductivities of the samples were measured by AC impedance spectroscopy. The results showed that the ionic conductivity increases at first and then decreases with raising doping amounts and sintering temperatures. So the optimized composition Li3/8Sr7/16-3x/2LaxZr1/4Nb3/4O3 (x = 0.05) sintered at 1275 °C was selected with the highest total conductivity of 3.33 × 10?5 S cm?1at 30 °C and an activation energy of 0.27 eV. Additionally, potentiostatic polarization test was used to evaluate the electronic conductivity. The optimal composition Li3/8Sr7/16-3x/2LaxZr1/4Nb3/4O3 (x = 0.05) as a possible Li-ion conducting solid electrolyte has an electronic conductivity of only 8.39 × 10?9 S cm?1. 相似文献