共查询到20条相似文献,搜索用时 31 毫秒
1.
F.V. Motta A.T. de Figueiredo V.R. Mastelaro L. Gomes E. Longo 《Journal of luminescence》2009,129(7):686-306
The photoluminescence (PL) emission in structurally disordered Ba0.8Ca0.2TiO3 (BCT20) powders was observed at room temperature with laser excitation at lines 355 and 460 nm. The structural evolution perovskite-like titanate BCT20 powders prepared by a soft chemical processing at different annealing temperatures were accompanied by X-ray diffraction (XRD) and X-ray absorption near-edge structure (XANES). Intermediate oxycarbonate phase was identified and your influence with PL emission was discarding. BCT20 annealed at 500 °C displays intense PL emission. The results indicate relationship between broad PL band and order-disorder degree. 相似文献
2.
C.-W. Cho M.R. Cha J.Y. Jang S.H. Lee D.J. Kim S. Park J.S. Bae S.D. Bu S. Lee J. Huh 《Current Applied Physics》2012,12(5):1266-1271
The Ba0.5Ca0.5TiO3 (BCT) composition dependent dielectric and structural properties of (1?x)K0.5Na0.5NbO3–xBa0.5Ca0.5TiO3 powders were investigated. Room temperature x-ray diffraction revealed the powder structure to transform from orthorhombic to cubic with increasing BCT composition. The frequency dependent dielectric constant measurements revealed a shift in the temperature of the maximum dielectric constant for at frequencies, suggesting that the system exhibits ferroelectric relaxor behavior. The system containing 15% BCT showed the closest calculated Curie–Weiss exponent to 2, which the exponent for a relaxor ferroelectric. 相似文献
3.
Jyoti Rani K. L. Yadav Satya Prakash 《Applied Physics A: Materials Science & Processing》2014,117(3):1131-1137
Lead-free polycrystalline ceramic 0.55Ba(Zr0.2Ti0.8)O3–0.45(Ba0.7Ca0.3)TiO3 (0.55BZT–0.45BCT) was synthesized by sol–gel method and the dielectric, impedance and optical properties of this ceramic were studied. X-ray diffraction analysis revealed the formation of pure perovskite phase with the coexistence of tetragonal and rhombohedral structures. The high value of dielectric constant (~6,985) with low dielectric loss (~0.013) was obtained at room temperature. Bulk and grain boundary resistances were measured by impedance analysis, which revealed negative temperature coefficient of resistance behaviour in this ceramic. The estimated value of optical band gap was found to be ~3.16 eV, which is related to the presence of intermediate energy levels. Two emission bands one at ~365 nm (UV region) and another at ~465 nm (blue region) were observed in photoluminescence spectrum at room temperature. 相似文献
4.
Mihail Secu Marin Cernea Corina Elisabeta Secu Bogdan S. Vasile 《Journal of nanoparticle research》2011,13(8):3123-3128
Nanocrystalline Ho-doped BaTiO3, with average nanocrystals size of 20 nm, have been prepared using a sol–gel combustion technique. The structural and morphological
properties of the powders have been investigated by X-ray powder diffraction and high resolution transmission electron microscopy.
Chemical states of the holmium on the Ba0.97Ho0.03TiO3 ceramic surface were analyzed using X-ray photoelectron spectroscopy. Furthermore, their photoluminescence properties were
analyzed. 相似文献
5.
采用改进的溶胶-凝胶方法在LaNiO3/Si(100)衬底上制备了MgO/(Ba0.8Sr0.2)TiO3多层薄膜.实验结果表明,MgO层的引入改变了(Ba0.8Sr0.2)TiO3的介电特性和漏电流行为,使薄膜的漏电 流降低了3个数量级,但介电常数也有相应降低.漏电流的显著降低是由MgO子层的高阻特性 以及微量Mg向(Ba0.8关键词:
0.8Sr0.2)TiO3多层薄膜')" href="#">MgO/(Ba0.8Sr0.2)TiO3多层薄膜
漏电流
介电常 数 相似文献
6.
Xiaorong Cheng 《Solid State Communications》2007,141(11):587-590
The dielectric and ferroelectric properties of (BaxSr1−x)0.77Ca0.23TiO3 ceramics with x=1 to 0.7 were studied and compared with those of BaxSr1−xTiO3 and Ba0.77Ca0.23TiO3 ceramics. It has been found that Sr doping of the Ba0.77Ca0.23TiO3 ceramics causes a drastic decrease of the Curie temperature, just like Sr doping of pure BaTiO3 ceramics, demonstrating a cell volume effect. However, the (BaxSr1−x)0.77Ca0.23TiO3 ceramics with x=0.9 and 0.8 have larger spontaneous polarization than those of the corresponding BaxSr1−xTiO3 and Ba0.77Ca0.23TiO3 ceramics, along with sufficient insulating properties. The enhancement of their polarization was explained by the increase of the lattice parameter c/a ratio due to the lattice distortion and strain developed in the ceramics. 相似文献
7.
The effects of B2O3 on the microstructure and microwave dielectric properties of the 0.4Nd(Mg0.4Zn0.1Sn0.5)O3–0.6Ca0.8Sr0.2TiO3 ceramic system were investigated with a view to their use in microwave devices. A B2O3-doped 0.4Nd(Mg0.4Zn0.1Sn0.5)O3–0.6Ca0.8Sr0.2TiO3 ceramic system was prepared by the conventional solid-state method. The X-ray diffraction patterns of the B2O3-doped 0.4Nd(Mg0.4Zn0.1Sn0.5)O3–0.6Ca0.8Sr0.2TiO3 ceramic system did not significantly vary with sintering temperature. A 0.5 wt% B2O3-doped 0.4Nd(Mg0.4Zn0.1Sn0.5)O3–0.6Ca0.8Sr0.2TiO3 ceramic system that was sintered at 1350 °C for 4 h had a dielectric constant of 38.3, a quality factor Qf of 35,000 GHz, and a temperature coefficient of resonant frequency of ?4.8 ppm/°C. 相似文献
8.
J.-G. Cheng X.-J. Meng J. Tang S.-L. Guo J.-H. Chu 《Applied Physics A: Materials Science & Processing》2000,70(4):411-414
Barium strontium titanate (Ba0.8Sr0.2TiO3) films with good ferroelectricity have been obtained by a developed sol-gel processing, using a 0.05-M spin-on solution.
X-ray diffraction and Raman spectroscopy investigations showed that the Ba0.8Sr0.2TiO3 film exhibited a tetragonal structure at room temperature. Field-emission scanning electron microscopy measurements revealed
that large columnar grains with the size of 100 to 200 nm in the film were formed from the highly dilute spin-on solution
with layer-by-layer homoepitaxy. Electrical measurements for the prepared Ba0.8Sr0.2TiO3 film showed a remnant polarization of 3.5 μC/cm2, a coercive field of 53 kV/cm, two distinctive phase transitions, lower dissipation factor, and good insulating properties.
These results indicate the sol-gel-derived Ba0.8Sr0.2TiO3 film from a 0.05-M solution is suitable for uncooled infrared detector applications.
Received: 19 August 1999 / Accepted: 11 October 1999 / Published online: 1 March 2000 相似文献
9.
Raman scattering investigation of phase transition in the ferroelectric Ba0.95Ca0.05TiO3 is reported. The results suggest onset of significant dynamic disorder at 105°C. This corroborates findings of recent structural
study regarding large positional disorder associated with Ti and O1 atoms well below the tetragonal to cubic transition temperature
(∼150°C). 相似文献
10.
G.F. Teixeira G. Gasparotto E.C. Paris M.A. Zaghete E. Longo J.A. Varela 《Journal of luminescence》2012,132(1):46-50
Lead Titanate Zirconate (PZT) perovskite powders were synthesized by microwave hydrothermal method (M-H) at 180 °C for different time periods (2, 4, 8 and 12 h) with the presence of aqueous polyvinyl alcohol (PVA) solution 0.36 g L?1. The X-Ray diffraction (XRD), SE-FEG as well as the measurements of photoluminescence (PL) emission were used for monitoring the formation of a perovskite phase with random polycrystalline distortion in the structure. Emission spectra with fixed excitation wavelength of 350 nm showed higher value for the powder obtained after undergoing 8 h of treatment. A theoretical model derived from previous calculations allows us to discuss the origin of photoluminescence emission in the powders, which can be further related to the local disorder in the network of both ZrO6 and TiO6 octahedral, and dodecahedral PbO12. The new morphology initially observed from the PZT perovskite crystal growth bearing the shape of fine plates is found to be directly related to photoluminescence emission with energy lower than that present in the PZT with cube-like morphology that emits in 560 nm. 相似文献
11.
具有准同型相界组分的0.5Ba(Ti0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-0.5BCT)陶瓷, 表现出优异的铁电、压电性能, 作为一种具有潜在应用前景的无铅压电材料得到广泛关注. 本文采用溶胶-凝胶方法在Si(100)基底上制备了BZT-0.5BCT压电薄膜. 使用原子力显微镜和扫描电子显微镜测量得到样品的形貌图, 形貌图表明该方法制备的无铅压电薄膜表面光滑, 晶粒大小均匀、呈半球形, 直径为80–100 nm, 厚度为1.7 μm, 膜的内部有气孔.摩擦力实验表明, 压电薄膜样品与硅针尖之间存在静电力的作用, 导致其摩擦力远大于硅针尖与SiO2之间的摩擦力, 但是两者的摩擦系数基本相同.划痕实验表明, BZT-0.5BC薄膜具有很强的法向承载能力, 但是切向抗磨损能力差, 样品的平均弹性模量为23.64 GPa± 5 GPa, 其硬度为2.7–4 GPa, 两者均略低于压电陶瓷Pb(Zr, Ti)O3材料的体态值.
关键词:
BZT-BCT薄膜
纳米摩擦力
纳米压痕
纳米划痕 相似文献
12.
C.B. SamantarayAnushree Roy M. RoyM.L. Mukherjee S.K. Ray 《Journal of Physics and Chemistry of Solids》2002,63(1):65-69
Thin films of Ba0.8Sr0.2TiO3 have been deposited on p-type Si substrate by radio frequency magnetron sputtering. Polycrystalline bulk Ba0.8Sr0.2TiO3 sample has also been studied for comparison. X-ray diffraction patterns reveal that both the bulk sample and thin films are polycrystalline without any preferential orientation and belong to paraelectric cubic phase. We have compared the room temperature Raman and IR spectra of powder and thin films (both annealed and as-deposited) of Ba0.8Sr0.2TiO3. The extra feature in the Raman spectrum for the annealed film has been explained as due to the presence of intergrain stresses from the submicron size grains in it. 相似文献
13.
V. M. Mukhortov Yu. I. Golovko A. V. Pavlenko D. V. Stryukov S. V. Biryukov A. P. Kovtun S. P. Zinchenko 《Physics of the Solid State》2018,60(9):1786-1792
The ability to grow the interfacial defect-poor Sr0.5Ba0.5Nb2O6 + Ba0.2Sr0.8TiO3 and Ba0.8Sr0.2TiO3 + Ba0.4Sr0.6TiO3 ferroelectric films onto the doped silicon substrates is discussed. A study of piezo-response via the quasi-static method (using the electrode area of 0.07 mm2) reveals that heterostructures possess an initial polarized ferroelectric state with a spontaneous polarization vector perpendicular to the substrate at any type of Si conductivity. The polarized state is established to refer to two-dimension stresses in the ferroelectric, which is tunable through a preprepared BaxSr1 – xTiO3 onto a sublayer substrate as well as to a thickness of this sublayer. Polarization switching in Sr0.5Ba0.5Nb2O6/Si and Ba0.8Sr0.2TiO3/Si heterostructures under the external field arises at only using the barium–strontium titanate sublayer predeposited onto silicon. A 15% decrease in switching polarization in Ba0.8Sr0.2TiO3/Ba0.4Sr0.6TiO3/Si structures is observed after 500 h. 相似文献
14.
Jiangying Wang Xiaoying Zhang Jingji Zhang Huiling Li Zhengfa Li 《Journal of Physics and Chemistry of Solids》2012,73(7):957-960
Dielectric and piezoelectric properties of (1?x)Ba0.7Sr0.3TiO3?xBa0.7Ca0.3TiO3 (BST?xBCT) (x=0.2–0.9) perovskite ceramics have been investigated. BCT has fully incorporated into BST lattice, forming a complete perovskite solid solution, whose lattice constant χ decreases almost linearly with increase in x from 0.2 to 0.4, while showing an anomalous expansion at 0.4<x≤0.6. This, together with the deviation of tetragonal–orthorhombic phase transition temperature (TO–T) from the linear relation TO–T (K)=?103.7x+239.3 at x=0.5, suggests that a small amount of Ca2+ has substituted for Ti4+. Curie temperature TC increases linearly with increase in x from 0.2 to 0.9, which is mainly contributed to the increase of the Ba/Sr ratio. The calculated degree of relaxation (γ) is in the range of 1.41–1.53, indicating that the BST–xBCT ceramics are ferroelectric materials with diffuse phase transition. Strain and piezoelectric constant (d33) decrease with increasing x, whereas planar electromechanical coefficient (kp) reaches a maximum (17.0%) at x=0.6. 相似文献
15.
《Current Applied Physics》2010,10(4):1017-1021
ZnSe nanowires have been synthesized by thermal evaporation of ZnSe powders on gold-coated Al2O3(0 0 0 1) substrates and then sheathed with TiO2 by sputtering. Our results show that sheathing Zn nanowires with thin TiO2 layers can significantly enhance the photoluminescence (PL) emission intensity. XPS analysis results suggest that the PL enhancement is attributed to increases in the concentrations of deep levels such as oxygen and titanium interstitials as well as the density of interface states. The PL emission of ZnSe nanowires is also enhanced by thermal annealing. Annealing in an argon atmosphere is more efficient in enhancing the PL emission than annealing in an oxygen atmosphere. 相似文献
16.
The optical properties of Ba1.6Ca0.4P2O7 doped with Ce3+ and Tb3+ are investigated. Under excitation at 280 nm the emission spectrum of Ba1.6Ca0.4P2O7:Ce3+ consists of a peak at 370 nm and a shoulder at the longer wavelength side. The emission spectra of Ba1.6Ca0.4P2O7:Tb3+ shows the well-known emission lines due to 5D4-7FJ transitions of Tb3+. The green emissions of Tb3+ ions are enhanced upon UV excitation through energy transfer from Ce3+ to Tb3+ ions. The efficiency of such an energy transfer is estimated based on spectroscopic data. The dependence of photoluminescence (PL) intensities of Ce3+ and Tb3+ emissions on Ce3+ or Tb3+ concentrations in the systems (Ba1.6Ca0.4P2O7:0.04Ce3+,xTb3+ and Ba1.6Ca0.4P2O7:xCe3+,0.04Tb3+) and the temperature dependence of PL emission spectra of Ba1.6Ca0.4P2O7:0.06Ce3+,0.04Tb3+ is also investigated. 相似文献
17.
K. Buse 《Applied physics. B, Lasers and optics》1997,64(4):391-407
3 , LiTaO3, BaTiO3, Ba1-xSrxTiO3 (, BST), Ba1-xCaxTiO3 (, BCT), KNbO3, KTa1-xNbxO3 (, KTN), Sr1-xBaxNb2O6 (, SBN) and Bi12(Si,Ti,Ge)O20 (BSO, BTO, BGO) are discussed. Utilizing the knowledge on the charge transport processes, consequences for applications are
deduced; improved techniques for nondestructive readout of holograms with light of the recording wavelength are described.
Received: 14. October 1996 相似文献
18.
L.S. Cavalcante J.C. Sczancoski F.S. De Vicente A.T. de Figueiredo M. Siu Li E. Longo 《Optics Communications》2008,281(14):3715-3720
Intense violet-blue photoluminescence (PL) emission at room temperature was verified in BaZrO3 (BZO) powders with structural order-disorder. Ab-initio calculations, ultraviolet-visible absorption spectroscopy and PL were performed. Theoretical results showed that the local disorder in the network-formed Zr clusters present an important role in the formation of hole-electron pair. The experimental data and theoretical results are in agreement, indicating that the PL emission in BZO powders can be related to the structural order-disorder degree in the lattice. 相似文献
19.
V. B. Shirokov Yu. I. Golovko V. M. Mukhortov Yu. V. Revinskii 《Technical Physics》2014,59(4):571-575
A Ba0.8Sr0.2TiO3/(Bi0.82, Nd0.02)FeO3 multilayer heteroepitaxial structure is prepared by successively depositing 20 Ba0.8Sr0.2TiO3 and (Bi0.82, Nd0.02)FeO3 layers, each 4 nm thick, using the method of rf sputtering. The layers grow on a single-crystal MgO substrate following the layer-by-layer mechanism. The structural perfection of the layers is examined by X-ray diffraction. The optical transmission is studied in the wavelength interval 200–1100 nm. The spectra are processed using a dispersion formula for the permittivity represented as a superposition of two oscillators with regard to relaxation. Such an approach allows us to separate direct and indirect transitions. The absorption edge of the superlattice for direct transitions is 80 nm wide and is estimated to be 3.78 eV. 相似文献
20.
We report a comprehensive study on relaxor-like characteristics exhibited by (l00) oriented 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 thin film grown on LaNiO3 coated Si substrate by pulsed laser deposition. The diffuseness coefficient value close to 2 and excellent fit of Vogel–Fulcher curve to the experimental data, suggest its relaxor characteristics. The ‘butterfly’ shaped dc field dependence of permittivity and evolution of P–E hysteresis loop, at different temperatures, clearly indicate the occurrence of polar nanoregions in this material. The high tunability nr ~ 70 and low temperature coefficient TCC = 5.18 × 10?4 K?1 show that the BCZT50 ceramics could be a promising candidate for tunable capacitor applications. 相似文献