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1.
The barium strontium titanate ceramics Ba1 − x
Sr
x
TiO3 with a spatially variable composition has been prepared according to the thick film technology (tape casting). The strontium
content over the film thickness is varied from 0 to 30 mol %. The structure and polarization characteristics of the samples
prepared have been investigated. It has been found that the polarization characteristics of multilayer structures are determined
by the ratio between the thicknesses of layers with different compositions and by their properties. No shift of the hysteresis
loops in the graded thick Ba1 − x
Sr
x
TiO3 (
x
= 0–0.3) films has been revealed. The results obtained have been analyzed in the framework of modern theoretical approaches. 相似文献
2.
The temperature dependences of permittivity and of hysteresis loops in the range of 4.2 K to 600 K were measured on mixed Ba1-xSrxTiO3 single crystals, grown in the whole concentration region 0≦x≦1 from a KF flux. It is shown that a solid solution with dielectric properties compatible with existing theories is formed by isovalent substitution of Ba by Sr only for x=0?0.4 and 0.8?1. A comparison between our results on single crystals and previous measurements on mixed ceramic materials is carried out. 相似文献
3.
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
4.
L. Zhang W. L. Zhong C. L. Wang Y. P. Peng Y. G. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,11(4):565-573
The size effect of the dielectric properties and the barrier height was investigated in the ferroelectric solid solution BaxSr1-xTiO3 system. The decrease of the grain size causes the suppression of the ferroelectricity, and the increase of the relaxation
frequency. Barrier heights increase with increasing grain size. The result is analogous to magnetic phase transitions in nanocrystals
and other solid-solid phase transitions in nanocrystals. It suggests a general rule that may be of use in the discovery of
new metastable phases. An explanation of this phenomenon was given by an electric potential model that agrees well with the
experimental results. For BaxSr1-xTiO3 system, the decrease of xcauses the decrease of the barrier height.
Received 3 August 1998 and Received in final form 22 November 1998 相似文献
5.
S.U. Adikary A.L. Ding H.L.W. Chan 《Applied Physics A: Materials Science & Processing》2002,75(5):597-600
BaxSr1-xTiO3 thin films with a compositional gradient of x=0.3 to 1 (in 0.1 mole fraction increments) were fabricated on Pt/Ti/SiO2/Si substrates using a modified sol–gel technique. The graded film crystallised in a perovskite structure and consists of
a uniform microstructure with comparatively larger grains. The room-temperature relative dielectric constant (εr) and dielectric loss (cosδ) at 100 kHz were found to be 305 and 0.03 respectively. Dielectric peaks were not observed in
the temperature range from -20 °C to 120 °C. The dielectric constant and dielectric loss were almost independent of temperature.
Polarisation–electric field measurements at room temperature revealed a saturated but slim hysteresis loop with a remanent
polarisation (Pr) of 0.6 μC/cm2 and a coercive field (Ec) of 2.4 kV/mm. The graded film behaves as a stack of BaxSr1-xTiO3 capacitors connected in series and hence the dielectric Curie peaks are removed.
Received: 4 October 2001 / Accepted: 17 October 2001 / Published online: 23 January 2002 相似文献
6.
Improvement of dielectric tunability and loss tangent of (Ba,Sr)TiO3 thin films with K doping 下载免费PDF全文
Zhang Wei-Jie Dai Jian-Ming Zhu Xue-Bin Chang Qing Liu Qiang-Chun Sun Yu-Ping 《中国物理 B》2012,21(9):97702-097702
Ba0.6Sr0.4TiO3 thin films doped with K were deposited on Pt/Ti/SiO2/Si substrates by chemical solution deposition method. The structure, surface morphology, and dielectric and tunable properties of Ba0.6Sr0.4TiO3 thin films have been studied in detail. The K content in Ba0.6Sr0.4TiO3 thin films has a strong influence on the material's properties including surface morphology, dielectric and tunable properties. It is found that the Curie temperature of K-doped Ba0.6Sr0.4TiO3 films shifts to higher values compared with that of undoped Ba0.6Sr0.4TiO3 thin films, which leads to a dielectric enhancement of K-doped Ba0.6Sr0.4TiO3 films at room temperature. At the optimized content of 0.02 mol, the dielectric loss tangent is reduced significantly from 0.057 to 0.020. Meanwhile, the tunability is enhanced obviously from 26% to 48% at the measured frequency of 1 MHz and the maximum value of the figure of merit is 23.8. This suggests that such films have potential applications for tunable devices. 相似文献
7.
M. E. Guzhva V. V. Lemanov P. A. Markovin W. Kleemann 《Physics of the Solid State》1997,39(4):618-624
Temperature-induced variations of light refraction and dielectric permittivity in single-crystal Sr1−x
BaxTiO3 (x=0.02, 0.05, 0.07, and 0.14), Sr1−x
CaxTiO3 (x=0.014), and in nominally pure strontium titanate have been studied within the 17–300 K temperature range. The spontaneous
polar contribution to the refractive index has been isolated. It was used to calculate the temperature and concentration dependences
of the polarization autocorrelation function 〈P
s
2〉
in the Sr1−x
BaxTiO3 system. For x⩽0.07, the polarization P
s=〈P
s
2
〉1/2 varies proportional to (x−x
g)1/2, where x
g=0.0027 is the new critical concentration in Sr1−x
BaxTiO3, below which short-range polar order vanishes.
Fiz. Tverd. Tela (St. Petersburg) 39, 704–710 (April 1997) 相似文献
8.
Microstructure and electrical properties of Mn-doped barium strontium titanate thin films prepared on copper foils 总被引:3,自引:0,他引:3
Ba0.7−xSr0.3MnxTiO3 (x = 0, 0.025, 0.05) thin films have been prepared on copper foils using sol-gel method. The films were processed in an atmosphere with low oxygen pressure so that the substrate oxidation is avoided and the formation of the perovskite phase is allowed. XRD and SEM results showed that Mn doping enhanced the crystallization of the perovskite phase in the films. The Mn substitution prevents the reduction of Ti4+ to Ti3+, which is supported by XPS analysis. The Ba0.7−xSr0.3MnxTiO3 film with x = 0.025 (BSMT25) exhibits preferred dielectric behavior and a lower leakage current density among the three thin films. The dielectric constant and loss of the BSMT25 film are 1213.5 and 0.065 at 1 MHz and around zero field, which are mostly desired for embedded capacitor applications. The mechanism of Mn doping on improving the electrical properties of barium strontium titanate (BST) thin films was investigated. 相似文献
9.
Based on Landau-Devonshire (LD)-type phenomenological
thermodynamic theory, the electric field dependence of the
dielectric properties of tetragonal single-domain barium strontium
titanate(Ba1-xSrxTiO3) films on cubic substrates is
theoretically investigated by taking into account the high order
terms of the polarization. At room temperature, the nonlinear
dielectric responses of epitaxial Ba0.6Sr0.4TiO3
films are provided by adjusting the film thickness and growth
temperature. The strong nonlinearity of relative dielectric
constant and pyroelectric coefficient are attained around critical
film thickness on MgO (69 nm) and LaAlO3 (132 nm) substrates or
critical growth temperature on MgO (337 °C) substrate with
respect to epitaxy-induced lattice misfit and thermal stresses
during deposition. This can be explained that small compressive
stresses are effective to support high nonlinearity of dielectric
constant and pyroelectric coefficient for
Ba0.6Sr0.4TiO3 films irrespective of whether they are
on compressive substrate or tensile substrate. It is also
predicted that a large tunability may be achieved by altering
processing conditions, such as the film thickness and growth
temperature for different substrates.
Our theoretical results are in good agreement with the experimental data reported in literature. 相似文献
10.
The Ba1?xSrxTiO3 (BST) ceramics were prepared by conventional ceramic method. The crystalline structure and morphology were studied by X-ray diffraction and scanning electron microscopy, respectively. Experimental results show that increase of sintering temperature leads to an uncontrolled precipitating of the phase with a lower content of Ti. The dielectric constant and specific heat as a function of composition and temperature were investigated. The increasing concentration of Sr ions leads to a shift of the Curie point below room temperature. To determine the elastic constants (the Young's modulus E, the shear modulus G and the Poisson's ratio v) of BST, a method of measurement of the longitudinal (νL) and transverse (νT) ultrasonic wave velocities for this type of material was developed. The structural, dielectric and mechanical properties of BST ceramics were discussed in terms of microstructure and chemical composition 相似文献
11.
The dielectric and ferroelectric properties of Ba1−xSrxTiO3 (BST) (x=0.10,0.20,0.30,0.40 and 0.60) ceramics and Ba1−2xSrxCaxTiO3 (BSCT) (x=0.10,0.20,0.30) ceramics have been investigated. The low temperature phase transitions of BST ceramics vanish after Ca2+ substitution while the high temperature transition is diffused and relaxed, which becomes more obvious with increasing x. Ca2+ substitution obviously decreases the dielectric constant maximum, Km, of BST ceramics and changes the temperature of dielectric constant maximum, Tm, of BST ceramics. The shift of Tm in BST is attributed mainly to the Sr2+ and Ba2+ concentration. BST ceramics exhibit almost normal ferroelectric characteristics, while a typical relaxor behavior was observed in BSCT ceramics. The relaxor behavior observations may be understood by a random electric field induced domain state. 相似文献
12.
The microstrip-ring-resonance technique has been applied to determine the dielectric properties of high-permittivity barium strontium titanate (BaxSr1-xTiO3) ceramics at microwave frequencies. A microstrip ring resonator of diameter 5 mm has been fabricated on the ceramics by the standard photolithography process. The transmission coefficient S21 spectra for the resonators have been measured using a vector network analyzer and simulated using a commercial electromagnetic simulation package, IE3D. By fitting the observed spectra to the simulated spectra, and tan of the BaxSr1-xTiO3 ceramics have been determined. The results obtained by this technique are in agreement with those determined by other conventional methods. This technique is relatively simple, especially for high-permittivity materials, since there are less rigorous requirements on the sample and the test conditions. PACS 77.22.-d; 77.84.Dy; 84.40.Az 相似文献
13.
Ba0.96Sr0.04Zrx Y0.005Ti0.995–xO3–δ ceramics were prepared by conventional sintering. The dielectric properties and the Curie temperature of the ceramics were studied. The Ba0.96Sr0.04Zrx Y0.005Ti0.995–xO3–δ ceramics (x = 0.04) exhibit a giant dielectric constant (εr ~ 105). The peak value of dielectric constant is ~250,000 at 100 Hz and ~70,000 at 1 MHz for Ba0.96Sr0.04Zrx Y0.005Ti0.995–xO3–δ ceramics (x = 0.04). The results show that Ba0.96Sr0.04Zrx Y0.005Ti0.995–xO3–δ (x = 0.04) ceramics are a promising candidate material for microelectronic applications. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
14.
The reasons responsible for diffusion of a phase transition are studied and the importance of composition fluctuations in ferroelectric and ferroelectric semiconductor solid solutions shown. Reduced form of the behaviour of physical characteristics in the vicinity of the second-order phase transition point is obtained. Agreement between the suggested theory and the experiment is demonstrated by the behaviour of dielectric permeability in the case of (Ba1?xSrx)TiO3. 相似文献
15.
A. V. Tumarkin E. R. Tepina E. A. Nenasheva N. F. Kartenko A. B. Kozyrev 《Technical Physics》2012,57(6):787-791
The electrophysical properties of bulk ceramics based on Ba x Sr1 ? x TiO3 solid solutions with a Mg-containing additive and planar variconds based on ferroelectric films obtained by the ion-plasma sputtering of targets with different elemental compositions are studied. Controllability n(U) = C(0)/C(U) and the dielectric loss tangent (tan??) of ferroelectric variconds are measured as functions of the elemental composition of the ferroelectric. The figure of merit of the variconds is estimated, and the film composition providing the best electrophysical parameters is determined. 相似文献
16.
17.
(001)La0.67Sr0.33MnO3/(001)(BaxSr1 ? x TiO3/(001)La0.67Sr0.33MnO3(x= 0–0.25) three-layer heterostructures are grown by laser evaporation on (001)La0.3Sr0.7Al0.65Ta0.35O3 single-crystalline substrates. In a wide temperature range (≈150 K), effective permittivity ? of (1000 nm)Ba0.25Sr0.75TiO3 and (1000 nm)SrTiO3 films grown obeys the relationship ? ~ (T ? T CW)?1, where T CW is the Curie-Weiss temperature for related bulk crystals. Using experimental dependences ?(T), the capacitance of the (001)La0.67Sr0.33MnO3/(001)BaxSr1?x TiO3 and (001)La0.67Sr0.33MnO3/(001)SrTiO3 interfaces, which is due to electric field penetration into the manganite electrode, is estimated (C int≈4μF/cm2). At bias voltages of ± 2.5 V, the change in the permittivity of the STO and BSTO films in the heterostructures studied reaches 25 and 45%, respectively. 相似文献
18.
Qing Xu Xiao-Fei Zhang Wen Chen Min Chen 《Journal of Physics and Chemistry of Solids》2010,71(11):1550-1556
Ba0.6Sr0.4TiO3 ceramics were prepared by a citrate precursor method. The structure and nonlinear dielectric properties of the resulting ceramics were investigated within the sintering temperature range 1200-1300 °C. Adopting fine Ba0.6Sr0.4TiO3 powder derived from the citrate method was confirmed to be effective in reducing the sintering temperatures required for densification. The ceramic specimens sintered at 1230-1280 °C presented relative densities of around 95%. A significant influence of sintering temperature on the microstructure and nonlinear dielectric properties was detected. The discrepancy in nonlinear dielectric behavior among the specimens sintered at different temperatures was qualitatively interpreted in terms of the dielectric response of polar micro-regions under bias electric field. The specimens sintered at 1230 and 1250 °C attained superior nonlinear dielectric properties, showing relatively low dielectric losses (tan δ) of 0.24% and 0.22% at 10 kHz together with comparatively large figure of merits (FOM) of 121 and 142 at 10 kHz and 20 kV/cm, respectively. 相似文献
19.
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
20.
X.-H. Zhu H.L.-W. Chan C.-L. Choy K.-H. Wong 《Applied Physics A: Materials Science & Processing》2005,80(3):591-595
Compositionally graded (Ba1-xSrx)TiO3 (BST) thin films, with x decreasing from 0.25 to 0.0, were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by pulsed-laser ablation at 600 °C and under ambient oxygen pressures ranging from 50 to 400 mTorr. The influence of the ambient gas pressure on the preferred orientation, microstructures, and dielectric properties of compositionally graded BST films was investigated by X-ray diffraction, scanning electron microscopy, and dielectric frequency spectra, respectively. As the ambient oxygen pressure was increased, the preferred orientation evolved in the order: (100)+(110)(110)+(111) random orientation, and the surface roughness of the graded BST films also increased. The graded BST films deposited at high ambient oxygen pressures (300400 mTorr) exhibited a grainy structure with polycrystalline grains throughout the film thickness, whereas the graded films deposited at low ambient oxygen pressures (50200 mTorr) possessed a columnar structure. The evolution of the microstructure was ascribed to the different physical and chemical properties of the species that were incident onto the substrates at the various oxygen pressures. The dielectric properties of the graded BST films were dependent upon the ambient oxygen pressures. The graded BST films deposited at 200 mTorr exhibited the highest dielectric constant. PACS 77.55.+f; 77.22.Ch; 81.15.Fg 相似文献