Індекс рубрикатора НБУВ: В379.273

Рубрики:

Магнітні властивості напівпровідників

Шифр НБУВ: Ж26988 Пошук видання у каталогах НБУВ 

Масиви нанодротів ZnO вирощено за механізмом пара - рідина - кристал на кремнієвих підкладках і досліджено за допомогою методів рентгенівської дифрактометрії, сканувальної електронної мікроскопії та атомно-силової мікроскопії. Результати цих досліджень свідчать про те, що діаметри нанодротів варіюються в межах 50 - 300 нм, а їх довжина сягає 40 мкм. Для вирощених нанодротів є характерною інтенсивна фотолюмінесценція, в спектрі якої домінують близькокрайова смуга та одна чи дві (залежно від умов вирощування) дефектні смуги. Співвідношення інтенсивностей цих смуг відображає нестехіометричність матеріалу і залежить від температури випаровування цинку та температури в зоні росту нанодротів.

Індекс рубрикатора НБУВ: Ж619 + В379.2

Рубрики:

Одержання плівок

Фізика напівпровідників

Шифр НБУВ: Ж16425 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В379.2

Рубрики:

Фізика напівпровідників

Шифр НБУВ: Ж16425 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В374

Рубрики:

Оптичні властивості твердих тіл. Оптичні властивості кристалів (кристалооптика)

Шифр НБУВ: Ж16425 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В345.4 + В379.24

Рубрики:

Електролюмінесценція

Оптичні властивості напівпровідників

Шифр НБУВ: Ж16425 Пошук видання у каталогах НБУВ 

Colloidal CdS:Mn nanoparticles were synthesized in water solutions of the polymer polyvinyl-pyrrolidone (PVP), the surfactant cetyl-trimethyl-ammonium bromide (CTAB) and the mixture of PVP and CTAB. The sizes of nanoparticles were determined by electron microscopy and optical absorption methods. The growth media influence on photoluminescence of nanoparticles has been studied. It has been shown that the chemical composition and structure of the adsorptive layer on the surface of nanoparticles can be used as a technological tool to control their light emission. The possibility to use CdS:Mn NPs grown in PVP as light-emitting labels in biological media has been demonstrated.

Досліджено кінетику синтезу колоїдних наночастинок (КНЧ) CdS:Mn у розчинах полівінілпіролідону та суміші полівінілпіролідону і полівінілового спирту за допомогою методів оптичного поглинання. Визначено залежності розміру, показника полідисперсності та концентрації наночастинок від концентрації прекурсорів у розчині. Проаналізовано фактори, які впливають на характеристики КНЧ. Виявлено, що використання суміші макромолекул полімерів впливає на кінетику синтезу та забезпечує стабілізацію середнього розміру наночастинок у ширшому діапазоні концентрацій прекурсорів у порівнянні з розчином одного полімеру. Продемонстровано можливість використання наночастинок, синтезованих у розчині полівінілпіролідону, як люмінесцентних міток для досліджень цільної крові.

Індекс рубрикатора НБУВ: Г612.1 + Г713.6

Рубрики:

Молекулярно-кінетичні та термодинамічні властивості дисперсних систем

Властивості розчинів полімерів

Шифр НБУВ: Ж16425 Пошук видання у каталогах НБУВ 

The nanocomposite - nanoporous silica (SBA-16) containing ZnO quantum dots - was fabricated by the sublimation method. This novel route of synthesizing ZnO nanoparticles implies physical sorption of zinc acetylacetonate precursor into the matrix pores from the gaseous phase, hydrolysis of the precursor, and thermal decomposition of the product with formation of ZnO nanoclusters directly inside the pores. The nanocomposite was characterized by XRD, nitrogen adsorption-desorption isotherms, and photoluminescence spectroscopy methods. We observed the blue shift of the ultraviolet luminescence of nanocomposite as compared to the luminescence of ZnO nanopowder as well as the decrease of the linewidth of the ultraviolet luminescence line, which points to the encapsulation of ZnO nanoparticles in the silica pores and narrowing of their size distribution.

The detailed analysis of the synthesis of CdS:Mn nanoparticles in polyvinyl alcohol polymeric matrix is presented and the ranges of optimal growth parameters are determined. The estimated values of parameters were used to produce solutions of CdS:Mn nanoparticles and corresponding solid composites. The sizes of nanoparticles and structure of composite films were characterized by electron microscopy methods, optical properties were probed using photoluminescence methods.

ZnO/porous silica nanocomposites were successfully fabricated by three different types of synthesis techniques. In all cases, the molecular sieve SBA-16 was used as a porous matrix. The in situ growth the nanoparticles of zinc oxide within the matrix pores was done using either gaseous or liquid precursors. The ex-situ method implied growing of nanoparticles in a colloidal solution with further penetration of the ripened ZnO nanoparticles into the pores of the matrix. Physico-chemical studies of the synthesized ZnO/porous silica nanocomposites showed that the introduction of zinc oxide by any of the methods did not lead to destruction of the structure of the molecular matrix SBA-16. The structure of ZnO nanoparticles, on the contrary, was strongly dependent on the growing method. The best defectless ZnO nanoparticles were obtained by in situ growing using gaseous precursors.

The novel ideas of negative refraction index (n) optics suitable for teaching special courses in universities at master's level are systematized and analyzed. The most important innovative ideas in this field are recounted in the logical order necessary for achieving the best understanding of the material. They are: the opposite signs of phase and group velocities of light; the change of the ordered right-hand triad of vectors E, B and V from the right-handed to the left-handed one; the change of the sign of the Doppler effect; the bent of the incident light, when entering the negative n material, in the "wrong" direction; the emergence of new class of materials - artificial metamaterials that have negative n; current state of the search for possibilities to achieve invisibility.

ZnO nanoparticles embedded in polyvinylpyrrolidone matrix were fabricated in situ by colloidal method with environmentally friendly reaction conditions. The colloid was used to form solid nanocomposite polyvinylpyrrolidone/ZnO, and optical properties of the material were studied. Two types of emission were identified in the nanocomposite: one originates from the polymeric matrix another is related the defect states in ZnO nanoparticles. Specific way of light emission excitation via energy transfer from the polymeric matrix to nanoparticles was observed.

Two nanocomposites containing CdS nanoparticles in polymeric matrices were studied using the photoluminescence (PL) and optically detected magnetic resonance (ODMR) methods. Due to equal sizes of NPs in the composites (~ 5 nm) but different matrices - the oxygen-containing polymer PVA (polyvinyl alcohol) and oxygen-free polymer PEI (polyethyleneimine) - differences of nanocomposites properties are predominantly caused by different interfacial conditions. ODMR spectra have revealed five types of centers related to the PL emission - four centers involved in radiative recombination and one center related to non-radiative recombination processes. The oxygen-related interfacial center in CdS/PVA (LK1-center) and sulfur vacancy center in CdS/PEI (Vs-center) were identified.

Purpose. Substantiation of an economically feasible method for developing the Kusmuryn deposit. Methodology. Analysis of literature and stock materials; studying physical and mechanical properties of rocks and ores. Findings. To improve economic performance and to reduce the cost of concentrate at the Kusmuryn deposit, the mining system is being changed. To replace the chamber-and-pillar development system, which allows extracting all the available reserves, a more effective model was introduced: development of inter-chamber pillars with a high metal content. The authors proved the expediency of development by the open method using the development system with horizontal layers with the goaf stowing. Originality. Calculating the technical and economic indicators of the three mining options allowed selecting the most effective mining method at the Kusmuryn deposit. In order to prevent underground fires, a layer caving system with siltation of crushed rocks is recommended. For disseminated ores, the usual method with collapsing overlying rocks is applicable. Practical value. Based on the studies, recommendations were developed for the Kazakhmys Corporation. They are referred to reducing the open pit mining at the Kusmuryn field in 2019. This stabilizes the achieved production level and compensates for retiring functioning facilities associated with the field. The introduction of underground mining is recommended from 2021.

Light-emitting properties of boron nitride powders of different morphology grown using various techniques have been studied. All samples were hexagonal BN (h-BN), while the content of impurity phases varied considerably. The wide photoluminescence band in the visible range has been observed. h-BN synthesized using carbothermal reduction method exhibited the highest efficiency of the photoluminescence emission. The intensity of BN emission has been interpreted in terms of interplay between the emission of intrinsic defects stabilized by carbon, carbon-related recombination centers and the centers of non-radiative recombination caused by the presence of sassolite phases in the samples.