共查询到20条相似文献,搜索用时 15 毫秒
1.
Grégory Houzet Thierry Lacrevaz Cédric Bermond Bernard Fléchet Arnaud Le Febvrier Stéphanie Députier 《组合铁电体》2014,158(1):52-61
A (100) oriented KTa0.65Nb0.35O3 400 nm-thin film has been deposited by Pulsed Laser Deposition on MgO substrate. Microwave measurements, performed on InterDigitated Capacitors, show a paraelectric phase at room temperature with a tunability for the devices of 64% under an electric field of 400 kV/cm. Then, using a specific de-embedding method, the complex permittivity of the KTN thin film has been extracted from 40 MHz up to 67 GHz on coplanar waveguides. As promising applications are pointed out at 60 GHz, such as indoor communications, material characterizations are expected in this spectrum. 相似文献
2.
A. A. Savvinov I. G. Siny R. S. Katiyar M. Pumarol H. A. Mourad F. E. Fernandez 《组合铁电体》2013,141(1-2):13-20
Abstract The renewed interest in KTa1?xNbxO (KTN) mixed perovskite materials, especially in thin films of a high quality, is connected with their remarkable dielectric properties in the dilute compositions. Off-center Nb ions in the highly polarizable KTaO3 lattice provide a drastic increase in the dielectric peak up to 20 times in comparison with pure KTaO3 and KNbO3. This paper reports a continuation of KTN thin films studies with several Nb concentrations in the range of 0 ≤ x ≤ 1 prepared by pulsed laser deposition from segmented KTaO3, KNbO3 and KNO3 targets. The effect of the substrate and symmetry-breaking defects was studied by micro-Raman spectroscopy. An anomalous residual intensity of the forbidden first-order scattering modes in the cubic paraelectric phase of the KTN films was connected with the formation of polar microregions even far above the bulk Tc value. On the whole, the KTN film behavior shows the existence of specific defects enlarging the perovskite unit cell in the film so that the activity of off-center Nb ions increases in producing larger electric dipoles and extending the precursor phase above Tc. 相似文献
3.
H.-M. Christen K.S. Harshavardhan M.F. Chisholm E.D. Specht J.D. Budai D.P. norton L.A. Boatner I.J. Pickering 《Journal of Electroceramics》2000,4(2-3):279-287
Epitaxial, uniformly strained superlattices of ferroelectric KNbO3 and paraelectric KTaO3 are studied with respect to their structural and dielectric properties. For dielectric measurements, perfectly lattice-matched conducting KNbO3Sr(Ru0.5Sn0.5)O3 electrodes are used, and a broad, frequency-dependent maximum is observed in the capacitance-vs-temperature curves. Niobium K-edge glancing-angle EXAFS provides information regarding the crystal structure of KNbO3 films as thin as two unit cells in superlattices with equal KTaO3 and KNbO3 layer thicknesses, showing a clear difference between these thinnest-layer superlattices and films of the KNbO3K(Ta0.5Nb0.5O3 solid-solution. X-ray diffraction measurements, on the other hand, indicate that these samples exhibit the same transition temperature KNbO3Tc, indicating the importance of long-range electrostatic interactions. Analysis of the transition temperature for various structures leads to a clear identification of the effect of size and strain on KNbO3Tc. 相似文献
4.
Youngsoo Park June Key Lee Yong Kyun Lee Ilsub Chung Jung Soo Yong Young Ho Park 《Integrated ferroelectrics》2013,141(1-4):231-238
Abstract Pb(ZrxTi1?x)O3 (PZT) ferroelectric thin films were prepared by metalorganic chemical vapor deposition (MOCVD) on Pt/Ti/SiO2/Si substrate. Very thin PZT films, which were deposited at a lower temperature and post-annealed at higher temperature for crystallization, were used as a seed layer. PZT films grown on the seed layer exhibited superior characteristics in the crystalline structure and electrical properties, compared to those deposited without seed layer. Depending on the deposition conditions of PZT seed layer, a wide variation of surface morphology and stoichiometry was found between samples, whereas chemical composition was found to be very similar. 相似文献
5.
Woong-Hee Lee Young-Jin Ko Mir Im Sang-Hyo Kweon Sung-Hoon Cho HaiBo Xu Chong-Yun Kang Sahn Nahm 《Journal of Electroceramics》2018,41(1-4):37-42
A K2-mNb2O6-m/2 single crystal with a pyrochlore phase formed when the Nb2O5?+?x mol% KOH specimens with 0.6?≤?x?≤?1.2 were solvothermally heated at 230 °C for 24 h. They have an octahedral shape with a size of 100 μm, and the composition of this single crystal is close to K1.3Nb2O5.65. The single-crystal KNbO3 formed when the single-crystal K2-mNb2O6-m/2 was annealed at a temperature between 600 °C and 800 °C with K2CO3 powders. When annealing was conducted at 600 °C (or with a small amount of K2CO3), the KNbO3 single crystal has a rhombohedral structure that is stable at low temperatures (< ? 10 °C). The formation of the rhombohedral KNbO3 structure can be explained by the presence of the K+ vacancies in the specimen. The KNbO3 single crystal with an orthorhombic structure formed when the K2-mNb2O6-m/2 single crystal was annealed at 800 °C with 20 wt% of K2CO3. 相似文献
6.
《Integrated ferroelectrics》2013,141(1):475-487
(1 ? x)PbMg1/3Nb2/3O3-(x)PbSc1/2Nb1/2O3 (PMN-PSN) solid solution crystals have been grown by the flux method in the whole concentration range. X-ray supercell reflections due to B-cation ordering were observed for as-grown crystals from the 0.1 ≤ x ≤ 0.65 compositional range. Though the ordered domains are rather large (~50 nm) the relaxor-like dielectric behavior is observed for compositions with x < 0.6. The diffusion of the dielectric permittivity maximum in as-grown crystals is the lowest at x = 0.6 and increases towards the end members of solid solution. Such behavior is explained within a Bragg-Williams approach by employing the random layer model. At x ~ 0.6 the excitation energy determined from the Vogel-Fulcher relation exhibits a jump which we regard to changing the kind of the polar regions from PbMg1/3Nb2/3O3 to PbSc1/2Nb1/2O3 related type. 相似文献
7.
Dan Lavric Rajesh A. Rao Qing Gan J. J. Krajewski Chang-Beom Eom 《Integrated ferroelectrics》2013,141(1-4):499-509
Abstract We have grown stoichiometric pure perovskite phase Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) thin films and PMN-PT/SrRuO3 heterostructures on miscut (100) SrTiO3 substrates by pulsed laser deposition. X-ray diffraction θ–2θ scans show that the PMN-PT films are purely c-axis oriented. The off-axis Φ scans show that the heterostructures grow “cube-on-cube” with an in-plane epitaxial arrangement of PMN-PT[100], [010] // SrRuO3[001] // SrTiO3[100] and PMN-PT[010], [100] // SrRuO3[110] // SrTiO3[010]. The crystalline quality of the films found to be comparable to that of bulk single crystals. The AFM images show that the SrRuO3 and PMN-PT layers have smooth surfaces with root mean square roughness of 9Å. These epitaxial heterostructures can be used for the fabrication of piezoelectric devices. 相似文献
8.
Carlos Ziebert Andris Sternberg Heinz Schmitt Karl-Heinz Ehses Jan K. Krüger 《Integrated ferroelectrics》2013,141(1-4):183-193
Abstract Nanocrystalline thin films of different relaxor materials, namely Pb(Sc0.5Ta0.5)O3 (PST), Pb(Sc0.5Nb0.5)O3(PSN), Pb(Mg1/3Nb2/3)O3(PMN) have been produced by RF-sputtering to investigate whether it will affect their dielectric properties if their grain size is reduced to the dimensions known from their nanodomains. The XRD shows that the amorphous film crystallizes in pyrochlore structure at lower temperatures and short times. Annealing at higher temperatures and far longer time intervals leads to an increasing amount of perovskite phase with a grain size in the nanometer range. These results including dielectric measurements will be presented and discussed. 相似文献
9.
The lead magnesium niobate [Pb(Mg1/3Nb2/3)O3 or PMN], and its solid solutions with lead titanate (PbTiO3 or PT), are of great interest because of their high electromechanical properties. At large PMN content, these materials exhibit relaxor characteristics with large electrostrictive strains and a large permittivity, while compositions near the morphotropic phase boundary present very interesting piezoelectric properties. So far, properties of these materials in ceramic, thin film and single-crystal form have been investigated. In this paper, we report on preparation and properties of pyrochlore free PMN and 0.65PMN-0.35PT thick films (thickness = 10 to 20 m). The films were prepared from ethyl cellulose ink by screen printing on alumina substrate. The influence of various parameters, such as powder characteristics, inks formulation and films sintering conditions, on films densification are discussed. The dielectric and electromechanical properties of the films were examined. Relaxor-like behaviour was clearly demonstrated in PMN films. The maximum relative permittivity for PMN film was 10000 (at 0.1 kHz), which is lower than in bulk ceramics (17800 at 0.1 kHz) prepared under the same conditions. For 0.65PMN-0.35PT, the maximum relative permittivity was around 15500 against 24000 in the bulk. Several parameters, which might be responsible for the lower permittivity, are discussed. Poled 0.65PMN-0.35PT thick films exhibit relatively large piezoelectric response (d
33 up to 200 pm/V) and unipolar strains approaching 0.1%, making these films of interest for various actuator and transducer applications. 相似文献
10.
Chul-Young Jang Joon-Hyung Lee Jeong-Joo Kim Sang-Hee Cho Hee Young Lee 《Journal of Electroceramics》2004,13(1-3):847-850
The effect of excess Nb2O5 on the phase stability of tungsten-bronze-structured K3Li2Nb5O15 (KLN) ceramics was studied. Stoichiometric KLN ceramics are not obtained as a single phase and second phases of KNbO3 and Li3NbO4 were observed. Additionally, stoichiometric KLN is difficult to sinter. In Nb-rich compositions, the second phase disappeared and a single KLN phase was obtained. This phase development behavior, that is, the phase stability of the KLN, was analyzed from the viewpoint of the electrostatic potentials of ions. The calculated Madelung energy of the completely filled stoichiometric KLN was unstable, while Nb-rich compositions showed much reduced Madelung energy, indicating that the ions were stabilized electrostatically. Enhanced sinterability in Nb-rich compositions is also discussed. 相似文献
11.
Kazumi Kato 《Integrated ferroelectrics》2013,141(1-4):93-100
Abstract The crystallographic orientation, microstructure and electrical properties of Sr2(Ta, Nb)2O7 thin films strongly depended on the composition (Ta:Nb). Post-annealing at 850°C was effective for the improvement of some properties. The thin films with relatively Nb-rich compositions, such as Sr2(Ta0.6Nb0.4)2O7 and Sr2(Ta0.5Nb0.5)2O7, showed the (0k0) preferred orientation. The Sr2(Ta0.5Nb0.5)2O7 thin film had a lamination layer structure after the post-annealing at 850°C for 6 min in oxygen. The characteristic microstructure originated in the crystallographic orientation of (0k0), which is the cleavage plane, and influenced electrical properties. The dielectric constant little change with the composition, however, the P-E hysteresis properties improved with the Nb content. 相似文献
12.
Abstract Highly oriented (Ba,La)Nb2O6 thin films have been synthesized by a chemical solution deposition method. A homogeneous and stable (Ba0.75La0.167)Nb2O6 (BLN) precursor solution was prepared by controlling the reaction of metal alkoxides. BLN precursor films crystallized in the tetragonal tungsten bronze phase at 700°C. BLN thin films on MgO(100) and Pt(100)/MgO(100) substrates showed the prominent c-axis preferred orientation. BLN thin films on Pt(100)/MgO(100) exhibited the diffuse phase transition depending upon the frequency. 相似文献
13.
Xiuming Li Quan Xu Guangtao Wu Baozhi Cheng Yonghao Liu Rui Yang 《Integrated ferroelectrics》2017,183(1):36-42
Surface acoustic wave propagation in a 0.955Pb (Zn1/3Nb2/3)O3-0.045PbTiO3 multidomain single crystal poled along [001]c has been analyzed theoretically using Christoffel wave equations. From the measured experimental data, the orientational dependence of surface acoustic wave phase velocities, electromechanical coupling coefficients and power flow angles was calculated. The results showed that surface acoustic wave propagations of 0.955Pb (Zn1/3Nb2/3)O3-0.045PbTiO3 are poor than 0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3 crystal slightly. However, the 0.955Pb (Zn1/3Nb2/3)O3-0.045PbTiO3 single crystals have higher rhombohedral-tetragonal phase transition temperature and much stabler electromechanical properties. This may expand applications range of SAW devices. 相似文献
14.
《Integrated ferroelectrics》2013,141(1):631-640
Highly crystalline Na0.5K0.5NbO3 (NKN) thin films of 1–2 μm thickness were deposited by rf-magnetron sputtering of a stoichiometric, ceramic target on single crystal LaAlO3(001) and Al2O3(0112) substrates. X-ray diffraction measurements revealed epitaxial quality of NKN/LaAlO3 film structures, whereas NKN films on sapphire substrates were found to be preferentially c-axis oriented. A prism-coupling technique was used to characterize optical and waveguiding properties. A bright-line spectrum at λ = 632.8 nm, revealed sharp peaks, corresponding to transverse magnetic (TM) and electric (TE) waveguide propagation modes in NKN/LaAlO3 and NKN/Al2O3 thin films. Using a least mean square fit the refractive index for the films and film thickness were calculated. The extraordinary and ordinary refractive indices were determined to n e = 2.207 ± 0.002 and n o = 2.261 ± 0.002, and n e = 2.216 ± 0.002 and n o = 2.247 ± 0.002 at λ = 632.8 nm for 2.0 μm thick NKN films on LaAlO3 and Al2O3, respectively. This corresponds to a birefringence Δn = n e ? n o = ?0.054 ± 0.003 and Δn = ?0.031 ± 0.003 in the films, where the larger Δn for the NKN/LaAlO3 structure can be explained by the superior crystalline quality compared to NKN/Al2O3. Atomic force microscopy images of the film surfaces revealed rms roughnesses of 2.5 nm and 8.0 nm for 1.0-μm thick NKN/LaAlO3 and NKN/Al2O3 films, respectively. We believe surface scattering is one of the main sources of waveguide losses in the thin films. 相似文献
15.
Abstract MgTiO3 thin films have been grown on various substrates by pulsed laser deposition (PLD) to investigate the application for microwave dielectrics and optical devices. Highly oriented MgTiO3 thin films were obtained on sapphire (c-plane Al2O3). MgTiO3 thin films deposited on SiO2/Si and platinized silicon (Pt/Ti/SiO2/Si) substrates were polycrystalline nature. MgTiO3thin films grown on sapphire were transparent in the visible and had a sharp absorption edge at 280 nm. These MgTiO3 thin films had extremely fine feature of surface morphology, i.e., rms roughness of 0.87 nm. Dielectric constant and loss of MgTiO3 thin films deposited by PLD were about 24 and 1.5% at 1MHz, respectively. These MgTiO3 thin films also exhibited little dielectric dispersion. 相似文献
16.
Abstract Methoxyethoxide complexes in 2-methoxyethanol were used to produce epitaxial thin films of SrBi2Nb2O9, SrBi2Ta2O9, BaBi2Nb2O9, and BaBi2Ta2O9 on [100] oriented single-crystals of SrTiO3 and LaAlO3. Films were prepared by spin coating substrates with alkoxide solutions and firing in air at 850 °C for 20 minutes. With the exception of BaBi2Ta2O9 on LaAlO3, all of the films were the desired c-axis oriented Aurivillius phase. Out-of-plane orientation was confirmed by θ-2θ scans which showed only [002/] reflections, and in-plane orientation was determined by phi-scans about the [105] plane. Lattice constants and full-width at half-maximum (fwhm) values for both in-plane and out-of-plane reflections are reported. 相似文献
17.
We report a systematic study of the (1???x)Pb(Sc1/2Nb1/2)O3–xPbTiO3 (PSN–PT) solid solution in the form of ceramics with compositions at or near the morphotropic phase boundary (MPB) region (0.35?≤?x?≤?0.50). The PSN–PT ceramics have been synthesized by an improved two-step wolframite precursor method. The synthetic process has been optimized in terms of calcining and sintering conditions. Both dielectric permittivity measurements and differential scanning calorimetry (DSC) show a clear peak at T C, at which the transition from the paraelectric to ferroelectric phase takes place. Interestingly, the solid solution of the MPB compositions displays a T C?>?200 °C, i.e. higher than the T C of the Pb(Mg1/3Nb2/3)O3–PbTiO3 and Pb(Zn1/3Nb2/3)O3–PbTiO3 solid solutions, making the PSN–PT system very promising piezoelectric and ferroelectric materials for high-temperature applications. A dielectric maximum as high as 50,000 is obtained for the 0.65PSN–0.35PT ceramic with losses smaller than 0.05. The values of the remnant polarization and the strain level of the PSN–PT ceramics are comparable to those of the PZT ceramics. 相似文献
18.
S. Migita K. Sakamaki H. Ota S.-B. Xiong Y. Tarui S. Sakai 《Integrated ferroelectrics》2013,141(1-5):135-143
Abstract Epitaxial thin film growth of SrBi2Ta2O9/SrTiO3/Ce0.12Zr0.88O2 on Si was studied, and this epitaxial layer structure was applied to fabrication of ferroelectric-gate field effect transistors (FETs). The films were prepared by a pulsed laser deposition technique and epitaxial growth was identified by x-ray diffraction. The devices exhibited excellent electrical performances: Capacitance-voltage characteristic of a metal-ferroelectric-insulator-semiconductor (MFIS) diode showed a retention longer than 10 days and Id-Vg characteristic of an MFIS-FET showed 1 day retention. It is proved that the crystalline quality of ferroelectric thin films is of great importance to develop integrated devices with high performance. 相似文献
19.
N. Pellegri A. Frattini C. A. Steren M. E. Rapp R. Gil R. Trbojevich 《Integrated ferroelectrics》2013,141(1-4):111-119
Abstract PbZr0.65Ti0.35O3 and Pb0.91La0.09Zr0.65Ti0.35O3 thin films with thickness of around 100 nm were prepared by the chemical solution deposition technique on Si (100) substrate. Complex metal alkoxide precursors were synthesized by alcoholisis and alcohol exchange reactions starting from metallorganics compounds. NMR spectroscopic techniques, 1H and 13C, and FTIR analysis were used to study the arrangement of the metals and oxygen in the precursor molecules. The films were deposited on Si (100) by spin coating technique and thermal treated by Rapid Thermal Processing for film crystallization. The thermal evolution and structural characterization were performed by DTA-TG/FTIR and by glazing incidence XRD and XRD powder. A PLZT powder with a well-crystallized perovskite structure was obtained at 700°C free of pyrochlore phase whereas the PLZT film exhibits a distorted perovskite structure and residual pyrochlore. The PZT films were less crystallized. The silicon substrate affects the crystal structure of the film. The residual acetylacetonate groups in the precursor of PLZT, would reduce the clustering of Zirconium species. 相似文献
20.
Monolithic multimaterial monomorphs, comprised of varying ratios of piezoelectric 0.65Pb(Mg1/3 Nb2/3)O3-0.35PbTiO3 to electrostrictive 0.90Pb(Mg1/3Nb2/3)O3-0.10PbTiO3, have been co-fired at 1150∘C. The relative permittivity, displacement, and polarization hysteresis were investigated for varying ratios of piezoelectric to electrostrictive material. The permittivity of the 1:1 multimaterial monomorphs followed the dielectric mixing laws, showing a dielectric constant of 5,500 at room temperature. The P-E hysteresis loop of the 1:1 sample exhibited a maximum and remnant polarization slightly less than the piezoelectric PMN-PT 65/35, but higher than the electrostrictive PMN-PT 90/10. Displacement was found to be higher for the 3:1 monolithic monomorph actuators, reaching 76 μ m at 6 kV/cm. The results indicate that by minimizing the electrostrictive layer thickness the tip displacement can be substantially increased while maintaining a lower hysteresis than that of the purely piezoelectric counterpart. 相似文献