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1.
The structure and dielectric characteristics of strontium barium niobate thin films deposited on single-crystalline silicon substrates without buffer layers are studied. It is found that the c axis in these heterostructures runs largely normally to the substrate surface and the a and b axes are randomly oriented in the plane of the substrate. The polarization relaxation in such heterostructures is investigated. It is shown that the film–substrate interface in the heterostructures grown by rf cathode sputtering may contain a low amount of long-lived charged defects. 相似文献
2.
I.?A.?Santos R.?G.?Mendes J.?A.?Eiras J.?de?Los?S.?Guerra E.?B.?Araújo 《Applied Physics A: Materials Science & Processing》2009,95(3):757-760
The dielectric properties of Sr0.75Ba0.25Nb2O6 relaxor ferroelectric thin films were carefully analyzed. In contrast to bulk samples which present three distinct dielectric
relaxation phenomena Sr0.75Ba0.25Nb2O6 thin films present only two of them. The suppression of the third anomaly can be mainly attributed to the narrow grain size
distribution of nanograins and weak tensile strains imposed to the film from the substrate. The whole set of results point
to the interpretation of a dielectric response characteristic of mesoscopic structure, which is composed of clusters and nanodomains. 相似文献
3.
V. V. Gladkii V. A. Kirikov T. R. Volk D. V. Isakov E. S. Ivanova 《Physics of the Solid State》2003,45(11):2171-2177
The dielectric properties of strontium-barium niobate crystals with a strontium concentration of 0.75, which corresponds to the most smeared ferroelectric phase transition, were measured. The dielectric hysteresis loops and the polarization relaxation are shown to exhibit clearly pronounced features characteristic of crystals with structural disorder and a broad distribution of a random internal electric field. The measurements were performed in dc, slowly varying (quasi-static), and pulsed electric fields. The experimental data obtained are used to construct the distribution function for the coercive field in the crystal bulk. 相似文献
4.
V. Ya. Shur V. A. Shikhova D. V. Pelegov A. V. Ievlev L. I. Ivleva 《Physics of the Solid State》2011,53(11):2311-2315
The results of the study of nano- and microdomain structure evolution in single crystals of relaxor ferroelectric strontium
barium niobate Sr0.61Ba0.39Nb2O6 doped by cerium are presented. It was shown that the initial nanodomain structure represents a self-similar three-dimensional
maze. The fractal dimension and average period were revealed. It was demonstrated that application of series of alternating
electric field pulses makes it possible to produce a single-domain state in the surface layer. The features of the growth
and “merging,” as well as the shape of ensembles of isolated nanodomains formed during switching from the single-domain state,
were investigated. The formation of the nanodomain ensembles was considered as a result of the self-organized discrete switching
controlled by determined nucleation. 相似文献
5.
X.T. Li P.Y. Du H. Ye C.L. Mak K.H. Wong 《Applied Physics A: Materials Science & Processing》2008,92(2):397-400
Textured LixNi2-xO (LNO) thin films have been fabricated on (001)MgO substrates by pulsed laser deposition technique. The as-deposited LNO
films shows a conductivity of 2.5×10-3 Ω m and possess a transmittance of about 35% in the visible region. Subsequent deposition of Sr0.6Ba0.4Nb2O6 (SBN60) thin film on these LNO-coated MgO substrates resulted in a textured SBN layer with a 〈001〉 orientation perpendicular
to the substrate plane. Phi scans on the (221) plane of the SBN layer indicated that the films have two in-plane orientations
with respect to the substrate. The SBN unit cells were rotated in the plane of the film by ± 8.2° as well as ± 45° with respect
to the LNO/MgO substrate. Besides the highly (00l)-orientation, the SBN films also exhibited a dense microstructure as shown
by scanning electron microscopy. The electro-optic coefficient (r33) of the SBN film was measured to be 186 pm/V. On the basis of our results, we have demonstrated that the LNO film can be
used as a buffer layer as well as a transparent bottom electrode for waveguide applications. The SBN/LNO heterostructure is
also a suitable candidate for integrated electro-optics devices.
PACS 42.79.Gn; 42.82.Et; 78.20.Ci 相似文献
6.
A. I. Burkhanov S. V. Kravchenko A. V. Shil’nikov I. P. Raevskii V. P. Sakhnenko 《Physics of the Solid State》2005,47(12):2299-2303
Long-time polarization relaxation in the temperature range where PBSN-6 single crystals reside in the relaxor state was studied. An analysis of the time dependence of the permittivity ε′(t) performed at measuring frequencies from 1 Hz to 1 kHz in weak electric fields E0 showed that the relaxation (or freezing) times derived by extrapolating relations of the type ε′(t) ~ log(t/t0) and ε′(t) ~ exp{?[ln(t/t0)]β} range from 108 to 1011 min and depend substantially on the bias voltage applied to the sample. A study of the pattern of the dielectric response in moderate and strong infralow-frequency fields revealed that, after a sample was maintained under a bias lower than the coercive force, it no longer exhibited the additional anomalies in the amplitude dependences of the effective loss tangent taneff(E0) than were observed in a thermally recuperated sample. 相似文献
7.
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
8.
We have investigated the relations between microstructure and dielectric properties in order to fabricate sol-gel-derived highly (100) oriented Ba0.5Sr0.5TiO3 (BST 50/50) thin films with properties comparable to those of the bulk material. For the first time, we were able to fabricate BST thin films which exhibited the orthorhombic-to-tetragonal transition in addition to the commonly observed tetragonal-to-cubic transition. We were successful in explaining the commonly observed degradation of the dielectric behavior of BST thin films, when compared to that of the bulk material, in terms of grain size, compositional inhomogeneity (measured in terms of Sr/Ba ratio) between the grain bulk and grain boundary, and mechanical stresses. PACS 77.55.+f; 77.22Gm; 77.80.Bh; 77.80.Dj 相似文献
9.
The temperature dependences of the permittivity, birefringence, optical transmittance, and small-angle light scattering and their variations with time are studied for single crystals of the Pb0.94Ba0.06Sc0.5Nb0.5O3 relaxor (PBSN-6) in the heterophase region of coexistence of different phases. It is shown that an electric field induces a phase transition to the ferroelectric state, which manifests itself within some time (delay time τ) after application of the electric field to the crystal. The observed dependence of the temperature of this transition on the heating rate of the sample and the changes in the birefringence and small-angle light scattering intensity with time confirm the kinetic character of the induced transition. Temperature dependences of the delay time τ for different electric fields are constructed. It is revealed that, at low temperatures, the delay time τ decreases with increasing temperature. This agrees with the behavior of τ in classical relaxors. At the Vogel-Fulcher temperature, however, one observes that dτ/dT reverses sign and τ increasing as the temperature continues to increase. This anomalous behavior of τ in the heterophase region is accounted for by the coexistence of the cubic relaxor and rhombohedral macrodomain phases. 相似文献
10.
E. N. Ubushaeva K. G. Abdulvakhidov I. V. Mardasova B. K. Abdulvakhidov M. A. Vitchenko A. A. Amirov A. B. Batdalov A. G. Gamzatov 《Technical Physics》2010,55(11):1596-1599
Polycrystalline multiferroic PbFe0.5Nb0.5O3 (PFN) fabricated by a solid-phase method is studied. Before sintering, a synthesized PFN powder is processed in Bridgman
anvils via a force action in combination with shear deformation (FASD) at room temperature. The electrophysical properties
and structural parameters of processed samples and a reference sample are compared. Point defects are shown to play a key
role in the formation of the physical properties beginning from an FASD of 200 MPa. 相似文献
11.
H. He W. Y. Zhang 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):457-463
The spin-states of cobalt based perovskite compounds depend sensitively
on the valence state and local crystal environment of Co ions and the
rich physical properties arise from strong coupling among charge, spin,
and orbital degrees of freedom. While extensive studies have been carried
out in the past, most of them concentrated on the isotropic compound
LaCoO3. In this paper, using the unrestricted Hartree-Fock approximation
and the real-space recursion method, we have investigated the competition
of various magnetically ordered spin-states of anisotropic double-layered
perovskite Sr2Y0.5Ca0.5Co2O7. The energy
comparison among these states shows that the nearest-neighbor
high-spin-intermediate-spin ferromagnetically ordered state is the relevant
magnetic ground state of the compound. The magnetic structure and sizes of
magnetic moments are consistent with the recent experimental observation. 相似文献
12.
Kai Jiang Jinzhong Zhang Wenlei Yu Zhigao Hu Junhao Chu 《Applied Physics A: Materials Science & Processing》2012,106(4):877-884
The Ba0.4Sr0.6−x
Mn
x
TiO3 (BSMT) ceramics with different Mn composition (from 1% to 10%) have been prepared via the conventional solid-state reaction
sintering. The X-ray diffraction analysis shows that the ceramics are polycrystalline with the single perovskite phase. The
lattice vibrations and optical properties have been investigated using Raman scattering, spectroscopic ellipsometry (SE),
and infrared reflectance spectra. It was found that the optical bandgap for the BSMT ceramics is varied between 3.40 and 3.65
eV. The three first-order Raman-active phonon modes can be observed, and the frequency of the A
1(LO3)/E(LO) mode shows a blue shift of 8 cm−1 with the Mn composition, which can be attributed to the distortion of the TiO6 octahedron. With increasing Mn composition, the frequency of the infrared-active TO4 mode decreases from 532 to 520 cm−1, owing to the local variation of the lattice constant induced by the Mn incorporation. Moreover, the optical functions of
the ceramics from the far-infrared to ultraviolet region are obtained based on the SE and reflectance spectra, which is useful
for the potential applications in ferroelectric-based optoelectronic devices. 相似文献
13.
L. S. Kamzina I. P. Raevskii V. V. Eremkin V. G. Smotrakov E. V. Sakhkar 《Physics of the Solid State》2003,45(6):1112-1117
The electric-field-induced variation of the optical properties (small-angle light scattering, birefringence) of PBSN-6 solid solutions was studied. It was found that in the absence of an electric field, the cubic nonpolar matrix contains, at temperatures below the dielectric permittivity maximum, spontaneously polarized regions of the ferroelectric phase not less than 104 Å in size. It was shown that a weak electric field (~0.4 kV/cm) is capable of inducing a kinetic phase transition to the ferroelectric state, with the temperature of this transformation depending on the sample heating rate. The destruction of the induced state was accompanied by a sharp peak in the temperature dependence of the small-angle light scattering intensity (indicating the percolation nature of the transition) and was independent of the sample heating rate. The boundaries of stability of the induced state in various modes of application of an external electric field were determined, and the E-T phase diagram was constructed. 相似文献
14.
V. B. Shirokov V. V. Kalinchuk R. A. Shakhovoi Yu. I. Yuzyuk 《Physics of the Solid State》2016,58(10):2035-2039
The behavior of material constants in ferroelectric Ba0.8Sr0.2TiO3 thin films is studied depending on the misfit strain at room temperature in the context of nonlinear thermodynamic potential of the phenomenological theory. Some constants are found to undergo drastic changes with the alternating strain at the interfaces. The gathered results allow one to evaluate the material constants for a specific film and to outline the direction in searching the ways to synthesize films with the needed properties. 相似文献
15.
The crystal structure and magnetic properties of the Bi1 ? x Ca x Fe1 ? x/2Nb x/2O3 system were studied. It is shown that, at x ≤ 0.15, the unit-cell symmetry of solid solutions is rhombohedral (space group R3c). Solid solutions with x ≥ 0.3 have an orthorhombic unit cell (space group Pbnm). The rhombohedral compositions are antiferromagnetic, while the orthorhombic compositions exhibit a small spontaneous magnetization due to Dzyaloshinski?-Moriya interaction. In CaFe0.5Nb0.5O3, the Fe3+ and Nb5+ ions are partially ordered and the unit cell is monoclinic (space group P21/n). In the concentration range 0.15 < x < 0.30, a two-phase state (R3c + Pbnm) is revealed. 相似文献
16.
Highly c-axis-oriented Sr3Bi4Ti6O21 (SBTi) thin films were fabricated on Pt-coated Si substrates by pulsed laser deposition (PLD). The structures were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). No peaks of SrTiO3 (STO) could be detected in the XRD pattern, indicating the existence of the SBTi single phase. Good ferroelectric hysteresis loops of the films with Pt electrodes were obtained. With an applied field of 400 kV/cm, the measured remanent polarization (Pr) and coercive field (Ec) values were 4.1 C/cm2 and 75 kV/cm respectively. The films showed little fatigue after 2.22×109 switching cycles: the nonvolatile polarizations decreased by less than 5% of the initial values. The dielectric constant and the loss tangent of the films were measured to be 363 and 0.04 at 100 kHz. These results might be advantageous for nonvolatile ferroelectric random access memory (NVFRAM) and dynamic random access memory (DRAM). PACS 77.84.Dy; 77.22.-d; 68.55.Jk 相似文献
17.
K. G. Abdulvakhidov M. A. Vitchenko I. V. Mardasova É. N. Oshaeva B. K. Abdulvakhidov 《Technical Physics》2007,52(11):1458-1461
PbIn0.5Nb0.5O3 (PIN) ferroelectric relaxer ceramics obtained by the solid-phase method is studied. Prior to sintering, the synthesized charge is subjected to mechanical action in Bridgman anvils at room temperature. The electrophysical properties of the reference sample and test samples are compared. It is concluded that mechanical treatment of the material at the stage of preparation allows one to control the physical properties of ferroelectric ceramics. Starting from a certain amount of the action, the electrophysical properties of PIN ceramics vary nonmonotonically. 相似文献
18.
Syed B. Qadri Anthony Garzarella Terrence Wieting Dong Ho Wu Nadeemullah A. Mahadik 《Applied Physics A: Materials Science & Processing》2009,94(4):1011-1013
Sr0.75Ba0.25NbO3 (SBN-75) has the tungsten-bronze structure with a tetragonal unit cell and exhibits electro-optic properties that are important
for sensors. Due to its quaternary nature, its structural uniformity, integrity, and homogeneity become important for these
applications. In this paper, we present high-resolution X-ray diffraction studies of the crystalline quality and lattice parameter
variation across the surface of single crystals of SBN-75. Using rocking curves, topographs, and point-wise measurements of
lattice parameters, we show that these crystals have a high degree of crystalline quality and microscopic homogeneity for
any electro-optic application. 相似文献
19.
The electronic structure of stoichiometric and oxygen-depleted Hf0.5Zr0.5O2 in the orthorhombic noncentrosymmetric phase has been studied by X-ray photoelectron spectroscopy and quantum-chemical simulation based on the density functional theory. It has been established that the ion-etching-induced peak in the photoelectron emission spectrum with the energy above the top of the o-Hf0.5Zr0.5O2 valence band is due to oxygen vacancies. A method of estimating the density of oxygen vacancies from the comparison of the experimental and theoretical photoelectron spectra of the valence band has been proposed. It has been established that oxygen polyvacancies in o-Hf0.5Zr0.5O2 are not formed: the energetically favorable spatial arrangement of oxygen vacancies in a crystal corresponds to noninteracting oxygen vacancies distant from each other. 相似文献
20.
Ba0.85Sr0.15TiO3 ferroelectric films on single-crystal silicon wafers were grown and studied. X-ray diffraction and electron microscopy studies showed that the films are characterized by a limited texture with a perovskite structure. It was shown that the grown films can be used as recording media for nonvolatile rerecorded data carriers in kinematic-type external memory devices. A possible mechanism of data recording and storage in the structures was considered. 相似文献