Showing papers by "Philips published in 1970"

Small-polaron versus band conduction in some transition-metal oxides

Abstract: In this paper an attempt is made to establish the nature of free charge carriers and of charge carriers bound to centres in p-type NiO, CoO and MnO and in n-type MnO and α-Fe2O3. For free charge carriers, d.c. conductivity, Seebeck coefficient and Hall effect are considered. Effects arising from inhomogeneous conduction and impurity conduction are discussed. Impurity conduction appears to have a strong influence on transport properties in the case of α-Fe2O3, less so in NiO, whereas no influence of this effect has been found in CoO and MnO. It is shown that NiO and CoO do not exhibit the features characteristic of small-polaron conductors but rather can be consistently conceived of as large-polaron band semiconductors. It is suggested that magnetic resistance due to exchange coupling between charge-carrier spin and cation spins plays an important role. The anomalous behaviour of the Hall effect in NiO and α-Fe2O3 is extensively discussed. In contradistinction to NiO, CoO and n-type MnO, free char...

Martensitic transformations in gold-titanium, palladium-titanium and platinum-titanium alloys near the equiatomic composition

Abstract: Alloys of compositions near AuTi, PdTi, and PtTi are B19-type orthorhombic at room temperature and, at higher temperatures, have an ordered CsCl-type structure (B2-type). The martensitic transformations involved were studied by X-ray diffraction. The composition dependence of the martensitic-transformation characteristics, such as Ms, Mf, As and Af-temperatures, were determined. Lattice constants of the high-temperature phases are given.

The crystal structure of rare-earth nickel compounds of the type R2Ni7

Abstract: Various rare-earth nickel alloys with 70–80 at.% Ni have been studied by X-ray diffraction and metallography. The lattice parameters of compounds of the type RNi3 and R2Ni7 have been determined for R = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Y. A structure determination is given for La2Ni7 and Sm2Ni7. Some of the compounds R2Ni7 have been observed to have two modifications. Indications have been obtained that the transformation between these two modifications is of the martensitic type. It is shown that the crystal structure of the R2Ni7 compounds is size-dependent.

The dysprosium-iron system: Structural and magnetic properties of dysprosium-iron compounds

Abstract: The DyFe system has been investigated over the whole concentration range by means of X-ray diffraction, thermoanalysis, and metallography. The constitutional diagram is given. Four intermetallic compounds have been observed: DyFe 2 , DyFe 3 , Dy 6 Fe 23 and Dy 2 Fe 17 ; the structure type and the lattice parameters are given. Measurements of the bulk magnetization have been performed on all DyFe compounds between 4.2 ° and 1200 °K. Their Curie points decrease with increasing iron concentration. The compounds DyFe 3 and Dy 6 Fe 23 show a compensation point.

The distribution of vacancies in lanthana‐doped lead titanate

Abstract: The incorporation of lanthanum sesquioxide in lead titanate has been investigated at constant temperature and at constant partial pressures of oxygen and of lead monoxide in respect of lanthanum contents in the range 0.5 ≦ y ≦ 50 mol%. The gravimetric method has been used to determine the amount of lead monoxide liberated by the incorporation of the lanthana and volatilized at high temperatures. In all probability the lanthanum ions occupy the lead sites in lead titanate. In the case of lanthanum contents y ≧ 5 mol% vacancies occur exclusively at lead sites, while in the case of lanthanum contents y < 5 mol% vacancies are formed also at titanium sites. Der Lanthanoxideinbau in PbTiO3 wird bei konstanter Temperatur und unter konstantem Sauerstoff- und Bleioxid-Partialdruck fur Lanthangehalte im Bereich 0,5 Mol% ≦ y ≦ 50 Mol% untersucht. Dabei wird auf gravimetrischem Wege die infolge des Lanthanoxideinbaus freiwerdende und bei hohen Temperaturen fluchtige PbO-Menge bestimmt. Die Lanthanionen besetzen im PbTiO3 mit aller Wahrscheinlichkeit Pb-Platze. Bei Lanthan-gehalten y < 5 Mol% entstehen ausschlieslich Leerstellen auf Pb-Platzen, wahrend bei La-Gehalten y ≧ 5 Mol% auch Leerstellen auf Ti-Platzen gebildet werden.

A New Class of Microstrip Directional Couplers

Abstract: By using Cohn's slotline in combination with a microstrip, simple 90/spl deg/ as well as 180/spl deg/ directional couplers of any coupling value can be made. As examples an ultra flat 10 db coupler for 1 - 12 GHz, an octave wide (2 - 4 GHz) magic tee and an almost lumped proximity coupler for 2 - 8 GHz (all on alumina substrate) have been made.

Crystal structure and magnetic properties of cerium‐iron compounds

Abstract: The crystal structure, the magnetic properties, and the phase relations of cerium-iron compounds have been investigated. A phase diagram is presented. Lattice constants are given for CeFe2, α-Ce2Fe17, and β-Ce2Fe17. The compound CeFe2 is ferromagnetic with Tc = 230° K. Investigations by means of the Mossbauer effect and bulk magnetization indicate an antiferromagnetic–ferromagnetic transition near 70° K and an antiferromagnetic-paramagnetic transition close to 270° K for the compound β-Ce2Fe17. The ordering temperatures and saturation moments for the CeFe compounds are compared with magnetic data presented for the isostructural YFe compounds. Die Kristallstruktur, die magnetischen Eigenschaften und die Phasenbeziehungen von Cerium–Eisen-Legierungen wurden untersucht. Ein Phasendiagramm wird angegeben. Die Gitterkonstanten werden fur CeFe2, α-Ce2Fe17 und β-Ce2Fe17 mitgeteilt. Die Verbindung CeFe2 ist ferromagnetisch mit Tc = 230° K. Untersuchungen mittels Mosbauereffekt und Volumenmagnetisierung zeigen einen antiferromagnetischen–ferromagnetischen Ubergang bei 70° K und einen antiferromagnetischen–paramagnetischen Ubergang bei 270° K fur die Verbindung β-Ce2Fe17. Die Ordnungstemperaturen und Sattigungsmomente fur die CeFe-Verbindungen werden mit magnetischen Daten verglichen, die fur die isostrukturellen YFe-Verbindungen angegeben werden.

Transport Numbers and the Structure of Porous Anodic Films on Aluminum

Abstract: Experiments are described in which aluminum samples, covered with a porous oxide layer by anodization in oxalic acid, are subsequently re‐anodized in boric acid ("forming"). The experimental techniques employed combine standard voltage and current measurements with gravimetric and optical methods for film thickness determination and measurements of the rate of film dissolution. The results show that for a given anodizing electrolyte the porosity depends only on the anodizing voltage and that it decreases with increasing voltage. The growth of the porous films is determined solely by the formation of oxide at the oxide/metal interface. This can be used to define a transport number for the positive ions during anodization, which was found to be . During forming in boric acid of a sample already covered with a porous oxide layer some of the oxide is formed in the pores and some at the metal/oxide interface. For this process a transport number was obtained. The average pore diameter, cell diameter, and barrier layer thickness vary linearly with the anodizing voltage, the cell wall thickness being somewhat thinner than the barrier layer.

Methods of manufacturing semiconductor devices

Abstract: A method of manufacturing a semiconductor device in which a process is effected at a semiconductor surface with the aid of an electron beam. A reference marker of a metal or metal based layer is provided at the semiconductor surface, the secondary electron emission pattern of the marker being used for registration purposes. The reference marker remains substantially inert and adheres to the surface during the process. Where two or more processes are effected at the semiconductor surface, each with the aid of an electron beam, the metal or metal based layer reference marker provides for accurate alignment at each process. The electron beam may be used for the selective exposure of an electron sensitive resist layer or for the selective electron bombardment of a layer of an organic silicon compound which yields an adherent oxide layer pattern on the semiconductor surface and may be used as a mask against impurity diffusion.

Methods of manufacturing a semiconductor device

Abstract: A method of making a semiconductor device is described which combines ion implantation with another process of forming an impurity-containing semiconductor region. In particular, a surface-adjoining region of a semiconductor is formed in such manner that the portion of that region adjacent the surface is formed by a process other than ion implantation, whereas a surface remote or buried portion of that region which defines a P-N junction is formed by ion implantation. This combination of steps yields improved semiconductor devices.

Thermal expansion, free volume, and molecular mobility in a carbon black-filled elastomer

Abstract: The thermal expansion of a butadiene–styrene copolymer filled with carbon blacks differing tenfold in mean particle size (HAF and MT) was investigated. The glass transition was unaffected by MT and was raised only 0.2°C for every 10 parts per hundred by weight of polymer of HAF black added. The coefficient of expansion of the polymer component of the composite in the rubbery region was substantially unaffected by either carbon black, but decreased markedly with increasing black loading in the glassy state. These results suggest that free volume is not altered appreciably by the presence of the filler in the rubbery state, but expands with decreasing temperature below Tg. The latter effect is explained by dilatation due to stresses set up around filler particles, arising from differences in the expansion coefficients of filler and polymer, which are not relieved in the glassy state. The near invariability of Tg and of the rubbery fected by adsorption of polymer segments on the carbon black surface. A conservative rough estimate indicates that restriction of segmental motion is confined to a 30 A layer around the particles in which Tg is elevated by only 10°C.

Hypodermic syringe with radially movable blocking elements

Abstract: A hypodermic syringe comprising a liquid container and a needle connected thereto at one end, which assembly is incorporated in a housing, the liquid container being bounded at the other end by a piston, and an operating mechanism being present to exert a force on the piston, one or more blocking elements being present for locking the operating mechanism or the piston against movement relative to the liquid container, the housing showing a diameter transition such that when the blocking elements pass along it, they are moved radially so that the blocking is removed and the piston penetrates into the liquid container so that the liquid flows out through the needle.

Coercivity and wall motion

Abstract: The process of magnetization reversal in ferromagnets with uniaxial crystal anisotropy is discussed. It is shown that the "critical-size concept" has no relevance to coercivity. Critical fields are distinguished as nucleation fields and propagation, or pinning, fields. The pinning of walls is discussed and illustrated by experiments on various substances. Intrinsic pinning in highly anisotropic materials is predicted.

Analytically Solvable Problems in Radiative Transfer. III

Abstract: The density of excited atoms and the diffusely reemitted radiation is calculated for a homogeneous radiation field incident on a slab. The solutions of the Biberman-Holstein integral equation are used in the calculations. The optical thickness is assumed to be large. The line shapes of both the absorption line and the incident radiation are arbitrary.

Energy Band Structures of Four Polytypes of Silicon Carbide Calculated with the Empirical Pseudopotential Method

Abstract: The electronic band structures of four polytypes of silicon carbide (3C, 2H, 4H, 6H) are calculated with the aid of local atomic pseudopotentials for carbon and silicon. The same pseudopotentials are used in all four polytypes. A description is given of the basic assumptions in the empirical pseudopotential method. A computer program is used which is able for symmetric k-values to reduce the dimensionality of matrices. The calculated energy band structures are in satisfactory agreement with well-established experimental data. D ie elektronischen Bandstrukturen von vier Polytypen des Siliziumkarbids(3C, 2H, 4H, 6H) werden mit lokalen atomaren Pseudopotentialen fur Kohlenstoff und Silizium berechnet, die in allen vier Polytypen gleich gewahlt werden. Die Grundlagen und die Anwendungsmoglichkeiten der empirischen Pseudopotentialmethode werden beschrieben. Ein Computerprogramm wird benutzt, in das eine Symmetrisierungsprozedur zur Verringerung der Dimensionalitat der Matrizen bei symmetrischen k-Punkten eingearbeitet ist. Die berechneten Bandstrukturen stimmen mit wohlbekannten experimentellen Daten gut uberein.