Highly-ordered nanoporous anodic aluminum oxide films

The samples of the nanostructured aluminum oxide films were obtained by anodic oxidation method (thickness is near 100 μm and dpores = 42+4 nm). Two stage aluminum oxidation was carried out in a two electrode electrochemical cell at 0°C and the voltage value of 40 V. Oxalic acid solution was used as an electrolyte. The optimal heat treatment conditions, of the weak luminescent films without destruction of the order structure have been proposed.Зразки плівок наноструктурованого окису алюмінію товщиною 100 мкм та розміром пор dпор = 42±4 нм отримано за допомогою методу анодного окиснсння. Двостадійне окиснсння алюмінію проводилося у двоелектродній комірці при 0°С при напрузі 40 В, у якості електроліту використано розчин щавлевої кислоти. Обрано оптимальні умови термообробки для одержання нелюмінeсцeнтних плівок без порушення високовпорядкованої структури.Образцы пленок наноструктурированного оксида алюминия толщиной 100 мкм и размером пор dпор = 42±4 нм получены при помощи метода анодного окисления. Двух стадийное окисление алюминия проводилось в двухэлектродной электрохимической ячейке при 0°С и напряжении 40 В, в качестве электролита использован раствор щавелевой кислоты. Выбраны оптимальные условия термообработки для получения оптически прозрачных образцов без нарушения высокоупорядоченной структуры

Luminescent ceramics based on polycrystalline calcium fluoroapatite Ca₁₀(P0₄)₆F₂:Eu³⁺

The FAP and FAP:Eu³⁺ powders have been prepared using precipitation from aqueous solution. The as-prepared powders were compacted into tablets at 660 MPa and sintered in oxygen atmosphere at 600-1200°C. XRD analysis has shown that within the whole range of sintering temperature, the samples contain crystalline fluorapatite along with a small amount of amorphous phase, which decreases as the sintering temperature rises. The sintering temperature elevation results in extension of the coherent scattering area size (L = 42 to 54 nm). The FAP:Eu³⁺ ceramics density attains 84.67 % at Tsint = 1100°C and decreases above that value. As the temperature increases, the average grain size grows from 5 to 15 μm and the porosity decreases. The photoluminescence efficiency of Eu³⁺ in the FAP structure is maximum for ceramics sintered at 1100°C.Порошки фторапатиту кальцію (ФАП) та ФАП:Eu³⁺ отримано методом осадження з водних розчинів. Свіжоприготовлені порошки компактувались у таблетки при 660 МПа та спікалися у атмосфері кисню у діапазоні температур Tsint = 600-1200°С. 3а даними XRD, у всьому діапазоні температур спікання поряд з кристалічною фазою ФАП присутня невелика кількість аморфної фази, яка з ростом температури спікання зменшується. 3 ростом температури спікання збільшується розмір областей когерентного розсіювання (L = 42-54 нм). Густина кераміки ФАП:Eu³⁺ досягає 84.67 % при Tsint = 1100°С і вище цього значення знижується. 3і збільшенням Tsint середній розмір зерен зростає від 5 до 15 мкм та пористість знижується. Вихід фотолюмінесценції Eu³⁺ у структурі ФАП є максимальним для кераміки, спеченої при 1100°С.Порошки фторапатита кальция (ФАП) и ФАП:Eu³⁺ получены методом осаждения из водных растворов. Свежеприготовленные порошки компактировались в таблетки при 660 МПа и спекались в атмосфере кислорода в диапазоне температур Tsint = 600-12000С. По данным XRD, во всем диапазоне температуры спекания наряду с кристаллической фазой ФАП, присутствует небольшое количество аморфной фазы, которое с ростом температуры спекания уменьшается. С ростом температуры увеличивается размер областей когерентного рассеяния (L = 42-54 нм). Плотность керамики ФАП:Eu³⁺ достигает 84.67 % при Tsint = 1100°С и выше этого значения снижается. С увеличением Tstnt средmrй размер зерен растет от 5 до 15 мкм и сmrжается пористость. Выход фотолюминесценции Eu³⁺ в структуре ФАП максимален для керамики, спеченной при 1100°С

Strong thermostable interference coatings for IR optical elements

Interference ZnO coatings for IR optical elements are obtained by the method of photothermal oxidation on the surface of crystalline ZnSe. Investigated are their mechanical and optical properties. The obtained oxide coatings possess high adhesion, homogeneity, withstand repeated thermocycling and irradiation with high-intensity CO₂-laser radiation. Revealed is the formation of islets of oxide films with elevated mechanical strength

Physical properties of ZnSe-MgSe, ZnSe-CdS solid solutions and possibilities of their application in IR engineering

The vertical Bridgman method is used to obtain crystals of Zn₁₋x Mgx Se and ZnSe-CdS solid solutions (with 0.03 Ј x Ј 0.55 and Cd concentrations varying from 0.3 to 35 at.%, respectively). The composition of the samples is determined by means of electron-probe microanalysis. The methods of optical microscopy and X-ray analysis are used to investigate the structure of the crystals and to determine their lattice parameters. Investigated are the micro-hardness and microbrittleness of the grown ZnMgSe crystals, as well as their polarizational, optical, photoelectric and dielectric properties depending on Mg concentration. The obtained crystals are found to possess anisotropy of physical properties. The largest anisotropy of their mechanical, polarizational and optical properties is observed in the crystals containing 5-6 at.% of Mg. The samples with such a concentration of Mg are applicable as a base for making thermostable multifunctional IR optical elements which can operate within a wide spectral region

Characteristics of the structure, composition and properties of electrodeposited zinc selenide films

The actuality of new processes for zinc selenide (ZnSe) films manufacture is explained by good prospects of their potential applications in optoelectronics. However, the films obtained on cathode by means of electrolysis in aqueous solutions have some distinctive properties and hence require a detailed study of structure, composition and properties thereof. Transmission electron microscopy examination of electrodeposited zinc selenide films has revealed that those are inhomogeneous in composition and structure: the fine-grained film body is formed by ZnSe nanocrystallites of cubic zinc blende structure and clusters of larger Zn(ОН)₂ microcrystals are included into the body. The film surfaces are coated by amorphous sublayer consisting of Se, Se0₂ and OSe(ОН)₂. According to electriсаl studies, such electrodeposited films are n-type semiconductors

Zn₁₋ₓMgₓSe single crystals as a functional material for optoelectronics

Structure, mechanical, optical, and electro-physical properties of single crystals of Zn₁₋ₓMgₓSe (0.03 0.12) have been found to be suitable as a functional material for manufacturing of thermally stable polarizing, electro-optical, and multifunctional devices intended to be operated under intense irradiation in near and medium IR range.Проведенi комплекснi дослiдження структурних, механiчних, оптичних та електрофiзичних властивостей монокристалiв твердого розчину Zn₁₋ₓMgₓSe (0,03 0,12) придатнi в якостi функцiонального материалу для виготовлення на їх основi термостабiльних поляризацiйних, електрооптичних та багатофункцiональних елементiв, призначених для роботи з iнтенсивним випромiнюванням ближнього та середнього IЧ дiапазонiв.Исследованы структурные, механические, оптические и электрофизические свойства монокристаллов твердых растворов Zn₁₋ₓMgₓSe (0,03 0,12) пригодны в качестве функционального материала для изготовления на их основе термостабильных поляризационных, электрооптических и многофункциональных элементов, предназначенных для работы с интенсивным излучением ближнего и среднего ИК диапазонов

Microhardness and brittle strength of ZnSe₍₁₋ₓ₎Teₓ crystals grown from melt

Mechanical properties of ZnSe₍₁₋ₓ₎Teₓ solid solutions (0 < CTe < 1.3 mass % ) have been studied using indentation method in two modes (indenting and scratching). The breaking limits for doped and undoped crystals have been measured by uniaxial compression. For the crystals where the dopant concentration CTe≈0.3 %, the microhardness anisotropy coefficient is equal to unity. This can be explained by disappearance of stacking defects in the crystals at the mentioned tellurium concentration due to favorable conditions for the sphalerite structure in the solid solution. As the Te concentration in the solid solution varies within the 0.2 to 1.3 % range, the crystal microhardness has been shown to increase linearly by 23 %. The fact has been confirmed by measuring the brittle fracture limit for Te doped and undoped ZnSe crystals. The fact can be explained by local distortions of ZnSe lattice due to Te atoms present and by the dislocation mobility decrease associated thereto, the combination of both factors results in the material strengthening. Effect of heat treatment and the block boundaries on the strength limit and cracking resistance of ZnSe₍₁₋ₓ₎Teₓ crystals has been established that is of importance when the material is subjected to machining

Study of deoxidization process of CsI melt by the action of "Zr-Pt" galvanic couple

The course of removal of oxide ion admixtures (deoxidization) from molten cesium iodide using galvanic couple zirconium-platinum at 973 K was studied by a potentiometric method using a membrane oxygen electrode Pt(O₂)⁄YSZ (YSZ - yttria stabilized zirconia) as an indicator one for the detection of current and equilibrium concentrations of O₂-. The running of the deoxidization in both cases is subjected to kinetics of 2nd order process with respect to O2- and the rate constant is as (3.07±0.31)·106 kg·mol⁻¹·min⁻¹·cm⁻² for the galvanic couple. Surface capacity of the galvanic couple with respect to oxide ions was estimated as 7.6·10-4 mol·cm⁻². The destruction and fixation of oxygen-containing admixtures in the case of the galvanic couple occur more intensively that in the case of pure zirconium and Zr-Pt combination is more promising agent for deep purification of growth halide melts