Using the RF cathode sputtering method, ferroelectric films of barium-strontium niobate Sr0.5Ba0.5Nb2O6 were synthesized on a semiconductor substrate. Their phase composition, crystal structure, nanostructure, dielectric, and ferroelectric characteristics were studied. The temperature ranges of phase transformations, the characteristic values of spontaneous polarization and coercive fields, the magnitude and nature of the change in the imaginary and real parts of the complex permittivity in the temperature range -190 divided by 250 degrees C were established in the films. The reasons for the revealed regularities are discussed.

Представлены результаты исследования диэлектрических характеристик тонких пленок ниобата бария-стронция Ba0.5Sr0.5Nb2O6, осажденных на монокристаллические подложки кремния различного типа проводимости без каких-либо буферных слоев. Пленки были получены методов высокочастотного катодного распыления в атмосфере кислорода. Обсуждаются причины выявленных закономерностей формирования диэлектрических характеристик.

BiFeO3/MgO(001) and BiFeO3/Sr0.61Ba0.39Nb2O6/MgO(001) heterostructuresHeterostructure were deposited by a one-stage technique of RF-cathode sputtering of a stoichiometric composition ceramic target in an oxygen atmosphere. The films were studied by X-ray diffractionX-ray diffraction and scanning electron microscopyScanning Electron Microscopy (SEM) at room temperature. It is shown that the heterostructuresHeterostructure have high crystal perfection and a low number of structural defectsDefect. It was found that the bismuth ferriteBismuth ferrite unit cell has monoclinic symmetry in the BiFeO3/MgO(001) heterostructureHeterostructure. There is only a slight unit cell strain in both heterostructuresHeterostructure. The presence of the Sr0.61Ba0.39Nb2O6 between BiFeO3 and MgO does not break the parallel of their crystallographic axes.

— Barium strontium niobate films ~300 nm in thickness have been grown on MgO(001) substrates by rf sputtering of a ceramic target with the stoichiometric composition Sr 0.5 Ba 0.5 Nb 2 O 6 (SBN50) in an oxygen atmosphere. Composition–depth profiles across the films have been measured using secondary ion mass spectrometry, and we have determined their phase composition, structure, and c cell parameter in the temperature range 20–500°C. The results demonstrate that the SBN50 films are heteroepitaxial and have two crystallographic orientations with an angle of ~36.8° between them and identical tetragonal cell parameters ( а = 12.438 Å and с = 3.955 Å). Their chemical composition does not vary in the thickness direction and corresponds to the composition of the ceramic target. The SBN50 films have a higher temperature of the ferroelectric-to-paraelectric phase transition than do SBN50 single crystals and polycrystalline films, and their thermal expansion coefficient changes sign near 100°C.

It has been established that in plates made of hot-pressed ferroelectric ceramics PZT-19 ([Formula: see text]C), after metal electrodes from Ag are burned into opposite surfaces with different depths of mechanical damage, counter-directional stationary deformation gradients and, accordingly, internal electric displacement fields create a stationary flexoelectric effect. As a result, unpolarized ceramics below the Curie temperature become a pyroelectric, and above it become a pyroelectric bolometer. After polishing the less damaged surface and replacing the Ag (valency [Formula: see text]) electrode with Cr ([Formula: see text]) by thermal evaporation in vacuum from the intact surface, a new thermally stable polarization is created, directed from the damaged surface in the interelectrode volume. Such plates have an asymmetric dielectric hysteresis loop, retain the values of the pyroelectric effect and piezoelectric effect in the ferroelectric phase, as well as the bolometric effect in the paraelectric phase after repeated heating cycles to [Formula: see text]C and cooling to [Formula: see text].

It has been established that after burning, the metal electrodes made of Ag into opposite surfaces of plates made of hot-pressed ferroelectric ceramics PZT-19 (Tc = 300 °C) with different depth of mechanical damage counter-directed stationary deformation gradients and, accordingly, internal displacement electric fields, are created. After replacing the Ag electrode with a valence of V = 3 for Cr with V = 6 from the side of the undamaged surface, a new heat-resistant polarization is created, directed from the damaged surface into the interelectrode space. Such plates have an asymmetric dielectric hysteresis loop, retain the pyro- and piezoelectric effect in the ferroelectric phase, and also the bolometric effect in the paraelectric phase, after repeated heating cycles up to 350 °C and cooling down to Tnorm.

AbstractUsing rf cathode sputtering of a target in the oxygen atmosphere, Ba_0.6Sr_0.4TiO_3 solid solution thin films have been formed on the single-crystal Si(001) cut surface and their crystal structure, microstructure, and optical characteristics have been investigated. It is shown that the films are optically anisotropic, polycrystalline, and have a c axis preferred direction perpendicular to the substrate. The a and b axes in the substrate plane have no preferred direction. It has been established that, during the synthesis, a buffer layer with a thickness of about 20 nm forms between the film and substrate, which is optically equivalent to silicon oxide.

The manufacture of electrode materials by the methods of sintering and cathodic sputtering of metals with different coefficients of linear thermal expansion on opposite surfaces of unpolarizedUnpolarized ceramic ferroelectric ceramics plates creates stationary gradients of mechanical deformations and stresses in specimens’ volume. As a result, an electrical response to the three-point mechanical loading (flexural vibrations at the resonant frequency) and pyroelectric current in the dynamic mode of measurement were observed.

Using rf cathode sputtering of a target in the oxygen atmosphere, Ba0.6Sr0.4TiO3 solid solution thin films have been formed on the single-crystal Si(001) cut surface and their crystal structure, microstructure, and optical characteristics have been investigated. It is shown that the films are optically anisotropic, polycrystalline, and have a c axis preferred direction perpendicular to the substrate. The a and b axes in the substrate plane have no preferred direction. It has been established that, during the synthesis, a buffer layer with a thickness of about 20 nm forms between the film and substrate, which is optically equivalent to silicon oxide.

Solid solution Sr 0.5 Ba 0.5 Nb 2 O 6 films have been synthesized on a (111)Pt/(001)Si substrate by rf deposition in an oxygen atmosphere. The depolarized Raman spectra, the structure, and the dielectric characteristics of the films have been studied over a wide temperature range. It is found that the films were singlephase, had the tetragonal tungsten bronze structure, and had a pronounced axial texture with axis 001 directed perpendicular to the substrate surface. It is shown that the film material undergoes a diffuse phase transition to the state of a relaxor ferroelectric in the temperature range 300–425 K. Possible reasons of the regularities observed are discussed.

Методом высокочастотного напыления в атмосфере кислорода получены пленки твердого раствора Sr0.5Ba0.5Nb2O6 на подложке (111)Pt/(001)Si. Изучены их деполяризованные спектры комбинационного рассеяния света, структура и диэлектрические характеристики в широком диапазоне температур. Установлено, что пленки однофазны, обладают структурой тетрагональной вольфрамовой бронзы, имеют ярко выраженную аксиальную текстуру с осью 001, направленной перпендикулярно поверхности подложки. Показано, что в интервале температур 300-425 K в материале пленки происходит размытый фазовый переход в состояние сегнетоэлектрика-релаксора. Обсуждаются возможные причины выявленных закономерностей. Работа выполнена в рамках реализации государственного задания на 2016 г N 007-01114-16 ПР (проект N 0256-2014-0002) и гранта РФФИ N 16-32-60095 мол\_а\_дк. DOI: 10.21883/FTT.2017.05.44376.382