排序方式: 共有74条查询结果,搜索用时 325 毫秒
21.
E. S. Gagarina E. I. Éknadiosyants L. A. Reznichenko L. A. Shilkina I. P. Raevskii V. P. Sakhnenko V. G. Smotrakov V. V. Eremkin 《Crystallography Reports》2002,47(6):979-990
The domain structure of single-crystal and ceramic samples of Na1 ? x LixNbO3 solid solutions (at x ≤ 0.14) in the orthorhombic ferroelectric and antiferroelectric phases at room temperature is investigated by optical and electron microscopies and X-ray diffraction. The characteristic feature of the domain structure is the formation of 90° complexes consisting of laminar domains with a specific orientation relative to the lattice of the initial cubic phase. Consideration is given to the specific features in packing of these complexes and typical configurations of domains in the crystals. Observations revealed that the domain structure can involve 90°, 60°, 120°, and 180° boundaries, as well as (hhl) boundaries of the S type whose orientation depends on the cell distortion and changes with a variation in x. The indices of these boundaries are determined. The density of 180° boundaries in the ferroelectric phase is very low compared to that of non-90° boundaries. 相似文献
22.
S. G. Karpova A. A. Ol’khov N. G. Shilkina A. A. Popov A. G. Filatova E. L. Kucherenko A. L. Iordanskii 《Polymer Science Series A》2017,59(1):58-66
Ultrafine fibers of biodegradable natural polyester such as poly(3-hydroxybutyrate) containing dipyridamole at various concentrations as a drug are prepared by the electrospinning method. It is shown by scanning electron microscopy that the absence of dipyridamole or its low concentrations (from 0 to 1%) provide the complex morphology of fibers composed of cylindrical regions 1–3 μm in diameter and thickened spindle-like ones 5–7 μm in average diameter. An increase in the concentration of dipyridamole in fibers leads to disappearance of the latter regions, with the morphology being cylindrical. The features of the crystalline and amorphous structures of poly(3-hydroxybutyrate) and its mixtures with dipyridamole are examined via DSC and EPR probe techniques. It is shown that the addition of dipyridamole to the poly(3- hydroxybutyrate) polymer matrix results in a sharp increase in the crystallinity and a slowdown of the molecular mobility in amorphous regions of ultrafine fibers. The heat treatment (annealing) of fibers leads to a sharp increase in the polymer crystallinity and a reduction of the segmental mobility in intercrystalline regions of the initial poly(3-hydroxybutyrate) fibers and those containing 1% of dipyridamole. All results including the influence of the drug concentration on the shape of fibers and their dynamic characteristics agree well with the thermal and physical parameters and should be used in the design of therapeutic systems for targeted and sustained delivery of bioactive compounds. 相似文献
23.
A. I. Miller A. A. Gusev I. A. Verbenko L. A. Shilkina L. A. Reznichenko 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(7):798-800
Methods of mechanochemical treatment applied to eliminate the disadvantages of BiFeO3 that impede its practical use are described. It is shown that the use of certain techniques for the mechanical activation of precursors allows us to enhance the structural and thermal stability of bismuth ferrite, to reduce its electric conductivity, and to improve its electrophysical properties. 相似文献
24.
25.
N. A. Boldyrev A. V. Pavlenko L. A. Shilkina A. V. Nazarenko L. A. Reznichenko A. I. Miller 《Bulletin of the Russian Academy of Sciences: Physics》2016,80(11):1303-1305
The structure, microstructure, and dielectric responses of (1–х)BiFeO3–xBaTiO3 (0.0 < x ≤ 0.5) solid solutions prepared as ceramics are studied. Patterns in their dielectric parameters and the formation of their crystal and grain structures are investigated in a wide range of temperatures and frequencies. 相似文献
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27.
I. N. Andryushina K. P. Andryushin O. N. Razumovskaya L. A. Shilkina L. A. Reznichenko Yu. I. Yurasov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(8):1127-1129
The behavior of the relative permittivity ɛ/ɛ0 of PbZr1 − x
Ti
x
O3 (PZT) solid solutions (0.495 ≤ x ≤ 0.51) in the temperature range of 100–300 K at frequencies from 1 × 10−2 to 2 × 107 Hz was investigated. Diffuse, strongly relaxing maxima at T = 230−260 K (x = 0.495−0.505) and 150–160 K (x = 0.510) were observed in the PZT studied. The relaxation processes are well described by the Vogel-Fulcher law, and the
dielectric spectra are approximated by the Cole-Cole formula. 相似文献
28.
A. A. Amirov A. B. Batdalov S. N. Kallaev Z. M. Omarov I. A. Verbenko O. N. Razumovskaya L. A. Reznichenko L. A. Shilkina 《Physics of the Solid State》2009,51(6):1189-1192
Thermophysical, magnetic, and dielectric properties of multiferroic BiFeO3 and Bi0.95La0.05FeO3 ceramic compounds were comprehensively studied. Anomalies of the permittivity near an antiferromagnetic phase transition related to the structural variations were detected. The temperature T N was determined from the temperature dependences of the thermal expansion coefficient, heat capacity, and differential susceptibility. It is shown that the transition point is shifted to higher temperatures as the rare-earth La ion substitutes for Bi. It is established that an insignificant substitution of lanthanum for bismuth enhances the magnetic properties of bismuth ferrite and the magnetodielectric effect. 相似文献
29.
V.?V.?AkhnazarovaEmail author L.?A.?Shilkina L.?A.?Reznichenko O.?N.?Razumovskaya S.?I.?Dudkina 《Crystallography Reports》2009,54(1):131-136
The effect of closed porosity p (from 1.0 to 13.6%) of sodium niobate ceramics on its phase state and structural characteristics has been investigated. It is shown that, with an increase in the porosity in the range 1.0 ≤ p ≤ 6.2%, the behavior of the structural parameters is determined by a gradual decrease in the content of the ferroelectric Q phase. At p ≥ 6.2%, their change is determined only by the porosity. The observed effects are interpreted within the model of deformed cation-anion bonds. 相似文献
30.
A. Ya. Dantsiger V. Z. Borodin L. A. Reznitchenko S. I. Dudkina V. A. Servuli S. V. Gavrilyatchenko L. A. Shilkina V. A. Borodina 《Technical Physics》2000,45(5):563-565
The effect is treated of the space charge field and of the crystallite size on the properties of ferroceramics of different
compositions. The established qualitative correlation between the structure and electrophysical parameters, the crystallite
size, and the space charge field may be useful in designing ferropiezoceramic materials for different applications and devices
involving such materials. 相似文献