Semiconductor Quantum Dots as Materials for Lasers Based on Them

Quantum dots (QDs) today belong to the central research objects of many scientific groups. The study of theproperties of structures of small size is important both for the further development of electronics, and for theimprovement of existing semiconductor devices. At present, there are many methods of obtaining QDsobtainingunder the laboratory conditions: the method of ultrasonic grinding, molecular beam epitaxy, pulsed laser ablation,as well as using such methods of chemical synthesis as organometall synthesis, synthesis in reverse micelles,electrothermal synthesis, sol-gel synthesis, synthesis using thiol stabilizers, synthesis in a non-aqueous medium.Nowadays, the most promising methods are based on the use of the phenomenon of self-organization. These aremolecular-beam epitaxy and colloidal chemistry methods, and the latter are used for synthesisof nanosizedcrystals.The band gap width and the energy of luminescence peak are determined by the size of the particles.Keywords: quantum dots; hydrothermal synthesis, solvothermal synthesis; semiconductor quantum dots;quantum-dimensional effects.</p

THE STRUCTURE OF THE ELECTRODE MATERIAL BASED ON Ni(OH)2/C COMPOSITE FOR ENERGY STORAGE DEVICES

The paper presents the results of studies of the structure β-Ni(OH)2/C composite. It is shown that the XRD-pattern of heated composite β-Ni(OH)2 /C has a broad diffraction peak at 23°, which can be attributed to the activated carbon in addition to peaks characteristic for NiO

THERMODYNAMIC PARAMETERS OF THE INTERCALATION REACTION IN THERMAL AND LASER MODIFIED NANODISPERSED ANATASE

It is modified matrix of anatase in turn of the thermal and laser treatments. The dependence of Gibbs energy change of the intercalation reaction of lithium with the guest load degree change was analyzed. Laser irradiation turned out to increase twice the value of maximum lithium “guest” loading, constricting heterophase area and changing contrarily concentration genesis of temperature dependence of entropy of lithium dilution. The optimal conditions of laser irradiation nanodispersive anatase (pulse energy E = 0,02 J, pulse duration τ = 15 ns repetition frequency f = 28 Hz, duration of exposure to 5 min.), at which specific energy characteristics of LPS, formed on its basis, increased by 55% is set

Effect of laser irradiation on Electrochemical Properties of composite MoS₂/C

The paper presents the results of studies of electrochemical properties of composite MoS&lt;sub&gt;2&lt;/sub&gt;/C. It is shown that the contribution to the conductivity of composites makes a charge accumulation capacitive nature inherent in high-conductive carbon, which is situated between the layers of MoS&lt;sub&gt;2&lt;/sub&gt;, improved charge transfer processes during charge / discharge, and quick turnaround faradeyivski processes inherent molybdenum disulphide. Found that the highest discharge specific capacity has laser irradiated composite MoS&lt;sub&gt;2&lt;/sub&gt;/C with a carbon content of 70% (209 F/g), due to the best combination of two mechanisms of charge accumulation and activation of charge carriers under the influence of laser. Keywords: molybdenum disulfide, activated carbon, composite, galvanostatic and potentsiodynamic methods, the accumulation of charge.</p

Electroinduced Diffusion of Lithium Ions into the Structure of Magnesium Fluoride

It has been established that in the process of intercalation/deintercalation of lithium ions into the MgF&lt;sub&gt;2&lt;/sub&gt;-based cathode material, thediffusion coefficient is (1-3)·10&lt;sup&gt;-12&lt;/sup&gt;сm&lt;sup&gt;2&lt;/sup&gt; /s during intercalation and(0,6-3)·10&lt;sup&gt;-11&lt;/sup&gt;сm&lt;sup&gt;2&lt;/sup&gt; /s during the inverse process. It shows the possibility of using MgF&lt;sub&gt;2&lt;/sub&gt; as a cathode material for a lithium element

The Composite Nickel Hydroxide / Activated Carbon as Electrode Material in the Battery Storage Devices

The paper presents theresults of studies of the structure and electrochemical properties of composite β-Ni(OH)2/C. It is shown that the diffractograms composites intered β-Ni(OH)2/C in addition tope aks characteristic NiO,there is a broad diffraction peak at23°, which can be attributed to the activated carbon. Found that the composite electrode based onβ-Ni(OH)2/C has a specific capacity, which is almost 25 times higher than the capacity for the output of nickel hydroxide at a current of 1m A. Keywords: nickel hydroxide, activated carbon,thermogravimetry, X-ray analysis, galvanostatic and potentsio-dynamic methods, the accumulation of charge.</p

Електричні властивості композитів на основі нанопористого вуглецевого матеріалу

In this work, the morphological and electrical properties of the composite nanoporous carbon material/thermally expanded graphite or acetylene black have been investigated. Nanoporous carbon material was obtained from plant materials by its thermochemical activation based on potassium hydroxide. The dependence of the specific capacity of the nanoporous carbon/electrolyte electrochemical system on the applied potential was determined by the impedance spectroscopy method. Furthermore, the concentration of charge transfer and the density of states, as well as the flat-band potential of the system under research, were determined based on the Mott-Schottky model.У роботі досліджено морфологічні та електричні властивості композиту нанопористий вуглецевий матеріал/терморозширений графіт або ацетиленова сажа. Нанопористий вуглецевий матеріал отриманий із рослинної сировини шляхом її термохімічної активації з використанням гідроксиду Калію. Методом імпедансної спектроскопії визначено залежність питомої ємності електрохімічної системи нанопористий вуглець/електроліт від прикладеного потенціалу. Використовуючи модель Mott-Schottky визначено концентрацію носіїв заряду, густину станів та потенціал плоских зон досліджуваної системи