Struktura fazowa oraz tekstura osadzonych elektrolitycznie stopów InSn na podłożu miedzianym

Stopy In-Sn są interesujące jako materiały dla technologii połączeń bezołowiowych oraz jako materiały zastępujące toksyczne warstwy kadmowe. W pracy badano warstwy indowo-cynowe osadzone z kompleksowych roztworów cytrynianowych. Kąpiele cytrynianowe są szczególnie atrakcyjne jako nietoksyczne kąpiele dla elektrolitycznego osadzania stopów. Osadzanie prowadzono w różnych warunkach hydrodynamicznych przy zastosowaniu wirującej elektrody dyskowej (WED). Stosowany potencjał, warunki hydrodynamiczne, pH, skład roztworu i dodatki składników organicznych miały silny wpływ na skład chemiczny, strukturę fazową i teksturę osadzonych warstw. Obliczono równowagi fazowe w układzie Cu-In-Sn i przedstawiono izoplety diagramu fazowego. W zakresie 25 do 400° C przeprowadzono badania termicznej stabilności osadów na podkładzie miedzianym przy zastosowaniu strukturalnej analizy rentgenowskiej.The In-Sn alloys are interesting as the materials used in the lead-free interconnection technology and as the replacement materials for toxic cadmium layers. This work investigated the indium-tin layers electrodeposited from the complex citrate solutions. The citrate electrolytic baths are especially attractive as the non-toxic baths for the electrodeposition of alloys. The depositions were conducted in various hydrodynamic conditions by means of the rotating disc electrode technique (RDE). It was observed that the applied potential, hydrodynamic conditions, pH, composition of solution and additional organic compounds have a strong effect on the chemical composition, the phase structure and the texture of the electrodeposited layers. The phase equilibria in the Cu-In-Sn ternary system were calculated and the isopleths of the phase diagram were presented. The X-ray structural investigations of the thermal stability of the deposits on the copper substrate were carried out in the temperature range from 25 to 400° C

Structural and Microstructural Analysis of Zn–Mo Alloy Layers Electrodeposited from Aqueous Citrate Solution

The paper presents results of the phase-composition and microstructure studies of the Zn–Mo alloy electrodeposited layers. The Zn–Mo coatings are electrodeposited from sulphate-citrate electrolytes on a steel substrate. As revealed in SEM, TEM and x-ray diffraction studies, the coatings consist of the phase crystallized in hexagonal system and contain less than 0.8% wt. Mo built-in the Zn-crystal structure. The presence of Mo atoms causes fragmentation of the crystallites.В статье представлены результаты исследований фазового состава и микроструктуры, электролитически осаждённых слоёв сплавов Zn–Mo. Покрытия Zn–Mo были получены на стальной подложке электролитическим осаждением из сульфат-цитратных электролитов. Исследования методами СЭМ, TEM и рентгеновской дифракции показали, что покрытия состоят из кристаллизованной в гексагональной системе фазы и содержат менее 0,8% масс. Мо, встроенного в кристаллическую решётку цинка. Наличие атомов Мо вызывает фрагментацию кристаллитов.У статті представлено результати досліджень фазового складу та мікроструктури електролітично осаджених шарів стопів Zn–Mo. Покриття Zn–Mo було одержано на сталевому підложжі електролітичним осадженням з сульфат-цитратних електролітів. Дослідження методами СЕМ, TEM і рентґенівської дифракції показали, що покриття складаються з кристалізованої в гексагональній системі фази та містять менше 0,8% мас. Мо, вбудованого у кристалічну ґратницю цинку. Наявність атомів Мо викликає фраґментацію кристалітів

Ovaries of Tubificinae (Clitellata, Naididae) resemble ovary cords found in Hirudinea (Clitellata)

The ultrastructure of the ovaries and oogenesis was studied in three species of three genera of Tubificinae. The paired ovaries are small, conically shaped structures, connected to the intersegmental septum between segments X and XI by their narrow end. The ovaries are composed of syncytial cysts of germ cells interconnected by stable cytoplasmic bridges (ring canals) and surrounded by follicular cells. The architecture of the germ-line cysts is exactly the same as in all clitellate annelids studied to date, i.e. each cell in a cyst has only one ring canal connecting it to the central, anuclear cytoplasmic mass, the cytophore. The ovaries found in all of the species studied seem to be meroistic, i.e. the ultimate fate of germ cells within a cyst is different, and the majority of cells withdraw from meiosis and become nurse cells; the rest continue meiosis, gather macromolecules, cell organelles and storage material, and become oocytes. The ovaries are polarized; their narrow end contains mitotically dividing oogonia and germ cells entering the meiosis prophase; whereas within the middle and basal parts, nurse cells, a prominent cytophore and growing oocytes occur. During late previtellogenesis/early vitellogenesis, the oocytes detach from the cytophore and float in the coelom; they are usually enveloped by the peritoneal epithelium and associated with blood vessels. Generally, the organization of ovaries in all of the Tubificinae species studied resembles the polarized ovary cords found within the ovisacs of some Euhirudinea. The organization of ovaries and the course of oogenesis between the genera studied and other clitellate annelids are compared. Finally, it is suggested that germ-line cysts formation and the meroistic mode of oogenesis may be a primary character for all Clitellata

Ovary cord micromorphology in the blood-sucking haemadipsid leech Haemadipsa japonica (Hirudinida: Arhynchobdellida: Hirudiniformes)

This is the first report that describes histological and ultrastructural details of ovary organization in haemadipsid leeches. In Haemadipsa japonica, the female reproductive system is organized similar to that of other haemadipsids. Each of the paired and oval ovaries of H. japonica is comprised of the ovary wall (ovisac), which encloses two elongated, thread-like ovarian units termed ovary cords. Ovary cords are comprised of germ-line cells and associated somatic cells. Each cord is polarized and contains germ-line cells in the consecutive developmental stages that are sequentially located along the long cord axis. There were three zones in each cord: the club-shaped apical part, the thread-like middle part, and the basal-most end, which contains degenerating germ cells. Outside of the reproductive period, the middle part of the cord in leeches is smooth, and no growing oocytes are visible; alternatively, in mature specimens, several growing oocytes protrude from the cord, and several huge vitellogenic oocytes that are completely detached from the cord occur within the ovisac. Ovary cord organization and functioning in H. japonica are very similar to the ‘Hirudo’ type cords that were found in several hirudiniform leeches. This conclusion supports the view that all hirudiniform leeches have conservative ovary cord organization and a similar pattern of oogenesis. Germ-line cyst composition, architecture, and functioning were also found to be evolutionarily conservative characteristics when compared with all previously examined Clitellata. In the germ-line cysts found in H. japonica each cell is connected to the central and anuclear cytoplasmic mass (cytophore) via one intercellular bridge, and, as oogenesis progresses, the fate of interconnected cell diversifies: some of them (oocytes) grow and complete oogenesis, but the majority become nurse cells and finally degenerate. Thus, oogenesis in H. japonica, similar to other clitellates, can be considered meroistic

X-Ray Topography of the Subsurface Crystal Layers in the Skew Asymmetric Reflection Geometry

The technique of X ray topography with the asymmetric reflection geometry of X-ray diffraction presented in this paper as useful tool for structural characterization of materials, particularly, epitaxial thin films and semiconductor multi-layered crystal systems used for the optoelectronic devices. New possibilities of this technique for a layer-by-layer visualization of structural changes in the subsurface crystal layers are demonstrated for semiconductors after various types of surface treatment, such as chemical etching, laser irradiation and ion implantation

Conditions for safe operations of power converters exposed to lighting and in mains generated overvoltages

Praca jest poświecona zagadnieniom przepięciowym w układach przekształtnikowych. Dokonano przeglądu zjawisk powstawania przepięć pochodzenia zewnętrznego i klasyfikacji tych przepięć oraz podano sposoby umożliwiające ich utrzymanie na dopuszczalnym poziomie.The paper deals with problems of overvoltages in power converters. A review of overvoltage arising phenomena of external origin, their classification and the measures for their maintenance within a tolerable level have been presented. (Insulation co-ordination in power electronic devices at voltage stresses of external origin)

Spatial Correlation of Impurity Charges Induced by Coulomb Interactions - Application to DX Centers in GaAs

The electron mobility enhancement observed in heavily doped GaAs under hydrostatic pressure is interpreted in terms of spatial correlation between the donor charges within partially occupied system of impurities induced by strong inter-donor Coulomb interaction. A simple analytic theory is given for both DX$\text{}^{0}$ and DX$\text{}^{-}$ models of the impurity state. The mobility is shown to increase together with pressure in both models. Estimates of the energy of the DX level are strongly perturbed by the inter-donor Coulomb interactions

Recombination Processes for Deep Impurity States Degenerate with the Conduction Band

We report on the studies of autoionization efficiency and the relevant recombination mechanism for Eu$\text{}^{2+}$ in Ca$\text{}_{x}$Cd$\text{}_{1-x}$F$\text{}_{2}$ depending on the energy level position of Eu$\text{}^{2+}$ excited states in respect to the conduction band states