Індекс рубрикатора НБУВ: В371.236 + В371.7

Шифр НБУВ: Ж100357 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В371.236 + Л719.943

Рубрики:

Пластмаси з металевими наповнювачами

Шифр НБУВ: Ж100357 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В371.236 + Л719.943

Рубрики:

Пластмаси з металевими наповнювачами

Шифр НБУВ: Ж100357 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В371.236 + Л719.943

Рубрики:

Пластмаси з металевими наповнювачами

Шифр НБУВ: Ж100357 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В375.147 + В376.1

Рубрики:

Вирощування кристалів. Вирощування монокристалів

Твердість. Пружність. Поширення звуку (пружних коливань) в монокристалах

Шифр НБУВ: Ж100357 Пошук видання у каталогах НБУВ 

The influence of ultrasound introduced into the melt during the growth of single crystals of gallium arsenide. Ultrasonic vibrations had a frequency of 820 kHz and amplitude of 0,1 - 0,2 micrometer. Found an increase in the homogeneity of impurity distribution of the bands growth without change of the dislocation structure of single crystals. In the simulation result of the ultrasonic wave interaction with the melt in the crucible on the basis of the theory of formation of phases is established that nucleation rate associated with the frequency and amplitude of the ultrasonic vibration acting on the melt.

It was found experimentally that on the initial part of crystal the fluctuations with amplitude more than 1 mm leads to break of the capillary column melt and close of growth. The physical significance of this functional relationship for this probably lies in the different orientation of surface tension forces. Regardless of the direction of stretching and an amplitude-frequency characteristics of development process of the power of the octahedral facets increased with increasing growth rate. Accidents on existing ideas are the result of periodic growth, due, for example, the rotation of the crystal in an asymmetric thermal field. When carrying out the method of crystal growth with perturbations at the interface it to a solid phase, the lateral surface is also composed of corrugations distinguishable to the naked eye.In general, the study of structural defects in the crystals obtained in exacting heat conditions, showed that in this case, lowfrequency disturbance of the melt at the interface reduces the average density of dislocations due to the periodic melting of crystallization and partially "heal" the defective portions of the crystals.

The method of effective surface impedance is proposed and applied for in situ characterisation of magnetic structures. For any ellipsometry investigations a proper choice of a physical model is important for solving the inverse problem. Reasonable approximations used for in situ ellipsometry monitoring are assumptions of a constant rate of layer growth and stable optical parameters. Standard ellipsometry analysis requires the model response to be calculated from every layer in the structure. Errors from underlying layers propagate through the entire structure and accumulate. In this case a method of a pseudosubstrate is used which approximates the underlying structure as a single interface (so called virtual interface), rather than tracking the entire sample history. The virtual interface is placed at some level and growth is modelled on this interface with no knowledge retained for the underlying structure. There are various methods for describing the virtual interface. In this paper, the concept of the effective impedance is used which requires only three measurement data points and is convenient for combined investigation of optical and magneto-optical properties. The algorithm is based on the calculation of the characteristic matrix of the layer (Abeles matrix) and surface impedance of the virtual interface using two ellipsometric experimental data points. The method is successfully used to analyse Co/SiCo films.

Metalcarbon nanocomposites based on polyacrylonitrile and nickel chloride are synthesized under the influence of infrared heat. The resulting materials represent a system of carbon matrix formed during the carbonization of PAN, and distributed in it nickel nanoparticles. The average size of the nanoparticles in the nanocomposite was 15 - 25 nm. It was found that the distribution of nickel nanoparticles sizes is determined by temperature synthesis nanocomposite. Thus with increasing temperature, the predominant average particle size of the metal increases, and the distribution is spread and shifted toward larger sizes.

It is found that the chemical composition of the metal component of nanocomposites satisfies the Fe:Co ratio, that was set on at the stage of preparation of the precursor, wherein there is a slight deviation from the initial metal concentration, due, apparently, to removing metal from the nanocomposite by the formation of volatile carbonyls of iron and cobalt in IR heating.

Індекс рубрикатора НБУВ: Г721.72-1 + Л712.72-101

Рубрики:

Полімери нітрилів: поліакрилонітріл, поліметакрилонітріл та ін.

Полімери нітрилів

Шифр НБУВ: Ж100357 Пошук видання у каталогах НБУВ 

It was found that the temperature fluctuations at the interface crystal-melt are the main reason for the formation of single crystals inhomogeneity grown by the Czochralski method. To reduce the heterogeneity of the layered method is proposed to reduce temperature fluctuations in the melt through the creation of artificial heat wave formed by the modulation of the heater temperature setting of growing single crystals. This paper describes the experimental technique to measure the temperature directly in the field of crystal growth of gallium arsenide from the melt. We investigated the possibility of special control actions for decreasing the temperature fluctuations at the crystallization front. These actions relate to the modification of the thermal and kinetic control parameters normally used in the Czochralski method of crystal growth, such as heater temperature, as well as crystal and crucible rotation rates. Unsteady low energetic thermal control actions (thermal waves, induced by periodic changes of the heater temperature) are able to eliminate temperature fluctuations near the crystal/melt interface and may be a potential tool for the growth of striation-free gallium arsenide single crystals.

Індекс рубрикатора НБУВ: К391.91-1 + В371.211 + В379.273

Рубрики:

Виробництво композитних металокерамічних матеріалів і виробів

Консолідовані наноструктури <Тіла тверді >

Магнітні властивості напівпровідників

Шифр НБУВ: Ж100357 Пошук видання у каталогах НБУВ 

The study of the peculiarities of the formation of the nanoparticles FeCo-alloy in the composition of metal-carbon nanocomposites FeCo/C. Structure, phase composition and kinetic processes of synthesis of nanocomposites FeCo/C by methods of Mossbauer spectroscopy were studied. This allowed us to establish the peculiarities of formation of nanoparticles FeCo alloy in the composition of the nanocomposites. The nanocomposites were synthesized by the IR-pyrolysis at temperatures of precursors of 300 - 800 °C on the basis of polyacrylonitrile (PAN), iron acetylacetonate and cobalt acetate. Also it is established that an increase in the average size of nanoparticles FeCo with increasing temperature synthesis is occurred. In the temperature range of synthesis of 600 - 800 °C the size varies from 9 - 10 to 16 - 18 nm, respectively. The features the phase transitions and phase composition of the metal-carbon nanocomposites FeCo/C were studied by Mossbauer spectroscopy. Nanocomposites were synthesized in the temperature range of T = 300 - 800 °C. It was shown that the samples synthesized at T = 300 °C contains of superparamagnetic nanoparticles of magnetite and amorphous oxide of iron only. The process of forming nanoparticles of alloy FeCo occurs within the temperature range 500 - 600 °C due to the recovery of amorphous iron oxide and magnetite as well as them dissolving in a phase of cobalt. The growth of size of nanoparticles of alloy by agglomeration and dissolution of iron in the alloy nanoparticles occurs only at the temperature range of synthesis 600 - 800 °C. This is confirmed by a decrease of the content of Fe, which associated with carbon and it is consistent with the results of phase and structural studies, carried out in previous works.

Індекс рубрикатора НБУВ: В379.273.4 + Л428.7

Рубрики:

Феримагнетизм. Ферити

Напівпровідникова і магнітна кераміка (магнетокераміка). Оксидна кераміка (кераміка чистих окислів)

Шифр НБУВ: Ж100357 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В379.273.4

Рубрики:

Феримагнетизм. Ферити

Шифр НБУВ: Ж100357 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: К390.1-1 + К391.91

Рубрики:

Виробництво металевих порошків

Виробництво композитних металокерамічних матеріалів і виробів

Шифр НБУВ: Ж100357 Пошук видання у каталогах НБУВ 

The main idea was to determine the conditions of macro- and micro-defects formation in single crystals of large diameter grown by the Czochralski method. It was found that the value of the average density of dislocations in the crystal cannot be regarded as a definite criterion of ongin or absence of the substructure. It was consider that the small-angle boundaries are the result polygonisation occurring mechanism slip or climb of dislocations in the crystal growth zone, closely related to the crystallization front. These boundaries can reach the solidification front, after which they inherited a growing crystal, forming macroblocks oriented along the growth axis.

Індекс рубрикатора НБУВ: Л420.7

Рубрики:

Випалювання керамічних виробів

Шифр НБУВ: Ж24320 Пошук видання у каталогах НБУВ