Showing papers by "Philips published in 1968"

Internal Reflection Spectroscopy

Abstract: Reflection of light is a surface phenomenon—it is strongly dependent on the nature of the surface and can therefore be used to study surfaces. If the surface is flat and smooth, the nature of the reflection is called specular, i.e., mirrorlike, and obeys the simple law that the angle of incidence equals the angle of reflection.

Spin-Disorder Scattering and Magnetoresistance of Magnetic Semiconductors

Abstract: The consequences of a simple type of exchange interaction between free charge carriers in a broad energy band and localized magnetic moments are discussed. The interaction causes a splitting of the energy bands into bands for the two spin directions. It also leads to spin-disorder scattering of the charge carriers. The temperature dependence of the mobility is calculated for ferromagnetic and antiferromagnetic semiconductors. Expressions are given for the magnetoresistance of ferromagnetic semiconductors.

Piezoelectricity in iii-v compounds with a phenomenological analysis of the piezoelectric effect

Abstract: The piezoelectric stress constants e14 of InSb, InAs, GaSb, GaAs, and AlSb have been measured at room temperature and found to be 0.071; 0.045; 0.13; 0.16, and 0.068 C/m2 respectively. If the III-V compound crystals are expanded in the direction, the A-faces (metal atoms) become negatively charged, in contrast to II-VI compounds, in which the equivalent faces become positively charged. Using a model of a layered lattice, we show that three different mechanisms may contribute to the piezoelectric effect. These mechanisms are 1. the internal displacement of the ionic charge, 2. the internal displacement of the electronic charge. 3. the change in ionicity due to strain. Die piezoelektrischen Konstanten e14 von InSb, InAs, GaSb, GaAs und AlSb wurden bei Raumtemperatur bestimmt. Sie sind in der gleichen Reihenfolge 0,071; 0,045; 0,13; 0,16 und 0,068 C/m2. Dehnt man eine III-V Verbindung in Richtung, so laden sich die A-Flachen (begrenzt durch Metallatome) negativ auf, im Gegensatz zu II-VI Verbindungen, in denen aquivalente Flachen positiv werden. An einem linearen Gittermodell wird demonstriert, das drei verschiedene Mechanismen zum piezoelektrischen Effekt beitragen konnen: innere Verruckung von Ionen, Innere Verruckung von Elektronen und Anderung der Ionizitat.

Intermetallic compounds in the system samarium-cobalt

Abstract: The system samarium-cobalt has been studied over the whole concentration range. The following compounds were observed: Sm 3 Co, Sm 9 Co 4 , SmCo 2 , SmCo 3 , Sm 2 Co 7 , SmCo 5 , α-Sm 2 Co 17 and β-Sm 2 Co 17 . The lattice parameters for these compounds have been determined, and, with the exception of Sm 9 o 4 , the structure type is given. Large homogeneity regions have been observed at higher temperatures for the compounds SmCo 5 and Sm 2 Co 17 . From the results of X-ray diffraction, thermo-analysis and metallography a tentative phase diagram has been constructed.

Rapid growth inhibition of gherkin hypocotyls in blue light1

Abstract: SUMMARY The elongation of dark-grown gherkin hypocotyls has been recorded continuously in darkness and on exposure to blue, red or far-red light. Evidence was obtained that the inhibition of elongation in blue light is not mediated by the phytochrome and “high energy reactions” but that a specific blue-light absorbing pigment is involved.

Hot-gas engine

Abstract: Apparatus for converting heat energy into mechanical energy, particularly a hot-gas engine, in which a working medium performs a cycle between an expansion space of higher temperature and a compression space of lower temperature, there being provided a heating system for supplying heat to the expansion space and a cooler for conducting away heat form the compression space. The heating system includes a reaction vessel containing a metal mixture heatable to a liquid phase and an oxydizing agent reservoir containing the oxydizing agent in the liquid phase, the oxydizing agent being supplied in a dosed gaseous form to the reaction vessel for exothermic reaction with the metal. The cooling water is passed from the cooler to the reservoir to provide heat from partially evaporating the liquid oxydizing agent therein.

Inflatable cushion and apparatus for making same

Abstract: AN INFLATABLE CUSHION OF DOUBLE-WALLEED CONSTRUCTION, THE INNER WALL BEING A BLADDER OF FLEXIBLE, IMPERFORATE AND HEAT-SEALABLE MATERIAL, SUCH AS POLYETHYLENE, AND THE OUTER WALL, IN PREFERRED MODE, BEING A NON-WOVEN PAPER FABRIC BONDED TO THE BLADDER ONLY ABOUT THE SELVEDGE OR THE BLADDER. THE BLADDER IS FORMED WITH AT LEAST TWO INTERCONNECTING CELLS BY MEANS OF TRANSVERSE SPOT SEALS. THE BLADDER IS PLEATED PARALLEL TO THE CELL LENGTHS TO SHORTEN THE LENGTH OF THE BLADDER IN A DIRECTION PERPENDICULAR TO THE SPOT SEAL INE. THE OUTER SKIN IS DIMENSIONED TO FIT OVER THE SHORTENED BLADDER WHEREBY, WHEN THE BLADDER IS INFLATED, THE OUTER SKIN FITS SNUGLY OVER THE BLADDER IN ALL DIRECTIONS. THE TWO WALLS PROVIDE COUNTER FORCES OF COMPRESSION AND TENSION WHEN WEIGHT IS APPLIED TO THE CUSHION. BY EMPLOYING LOW-COST POLYETHYLENE FOR THE BLADDER AND A NON-WOVEN PAPER FABRIC ON THE OUTER LAYER A VERY INEXPENSIVE CUSHION IS PROVIDED WHICH MAY BE DISCARDED AFTER A SHORT PERIOD OF USE. AN APPARATUS FOR MANUFACTURING THE CHSHION INCLUDES A PAIR OF ROLLS OF HEAT SEALABLE MATERIAL, SUCH AS POLYETHYLENE, A NOZZLE APPLYING STATION ADAPTED TO ATTACH AIR NOZZLES AT SELECTED POSITIONS ALONG THE WEB WHICH IS INDEXED HORIZONTALLY, HEAT SEALING ROLL TO JOIN THE TWO SUPERIMPOSED WEBS ALONG HEAT SEAL LINS, PLEATING GUIDES TO GATHER THE WEB AND A PAIR OF OPPOSITELY MOUNTED ROLLS OF NON-WOVEN FABRIC TO APPLY THE OUTER SKIN. ANOTHER HEAT SEAL ROLLER IS PROVIDED FOR MARGINALLY BONDING THE FABRIC TO THE BLADDER AND A CUT OFF STATION SEPARATES THE COMPLETED UNITS FROM THE WEB.

Experimental evidence for interband mixing in rare-earth intermetallic compounds.

Abstract: Measurements of the Knight shifts and susceptibilities of rare-earth intermetallic compounds have been extended to YCu, GdCu, TbCu, DyCu, HoCu, and ErCu. The phenomenological exchange constants sf between 4f-electron spins and conduction-electron spins are derived to be −0.21 eV. Also the paramagnetic Curie temperatures of the compounds GdCu1−xGax have been measured. The Knight shifts and Curie temperatures are discussed in terms of the Ruderman-Kittel-Kasuya-Yosida theory. For the various series of rare-earth intermetallic compounds the s-f exchange integral Γ = 2 J(0) and the Fermi wave vector kF have been determined. Γ is found to be a continuous function of kF, with a sign reversal at kF ≈ 1.4 A−1. This observed behavior is consistent with the calculations of Watson, Koide, Peter, and Freeman on the effect of interband mixing on the exchange interactions. Messungen der Knight-shifts und der Suszeptibilitaten der intermetallischen Verbindungen der Seltenen Erden wurden auf YCu, GdCu, TbCu, DyCu, HoCu und ErCu ausgedehnt. Die phanomenologischen Austauschkonstanten sf zwischen den Spins der 4f-Elektronen und den Spins der Leitungselektronen wurden zu −0,21 eV bestimmt. Die paramagnetischen Curietemperaturen der Verbindungen GdCu1−xGax wurden ebenfalls gemessen. Die Knight-shifts und die Curie-Temperaturen werden mit der Ruderman-Kittel-Kasuya-Yosida-Theorie diskutiert. Fur die verschiedenen Serien der intermetallischen Verbindungen der Seltenen Erden wurden das s–f-Austauschintegral Γ = 2 J(0) und der Fermi-Wellenvektor kF bestimmt. Es wurde gefunden, das Γ eine stetige Funktion von kF ist, mit einem Vorzeichenwechsel bei kF ≈ 1,4 A−1. Dieses Verhalten stimmt mit den Berechnungen der Wirkung der Interbandmischung auf die Austauschwechselwirkung von Watson, Koide, Peter und Freeman uberein.

Photomagnetic Effect in a Chalcogenide Spinel

Abstract: Photomagnetic change in the initial permeability has been investigated in Ga-doped Cd${\mathrm{Cr}}_{2}$${\mathrm{Se}}_{4}$. A simple model is shown to account satisfactorily for the experimental data.

Photoinduction of phenylalanine deaminase in gherkin seedlings : III. Effects of excision and irradiation on enzyme development in hypocotyl segments.

Abstract: 1. If hypocotyl segments from gherkin seedlings are floated on water the level of the enzyme phenylalanine deaminase (PADAse) increases for about 30 hours (25°) and then remains constant. The pattern of these changes differs from that of the photoinduced changes in the PADAse level in intact seedlings, where an initial increase in enzyme level is followed by a decline that starts at 25° about 3 hours after the beginning of irradiation. 2. The development of PADAse in the segments is inhibited by cycloheximide and puromycin, inhibitors of protein synthesis, and by the end products of its reaction, namely, cinnamic acid and p-coumaric acid. Repression due to the accumulation of p-coumaric acid is the likely reason why the irradiation gradually loses its effect on the induction of PADAse in intact seedlings whereas the derepressing effect of excision could be explained by the disappearance of p-coumaric acid from the segments. 3. Application of cinnamic acid or p-coumaric acid to the segments 16 hours after excision results in a drop in the PADAse level. Cycloheximide prevents this decline. These findings indicate the induction of a PADAse inactivating system requiring de novo protein synthesis, probably the same system found to be responsible for the drop in enzyme level in intact seedlings. 4. Irradiation of the segments with blue light stimulates the PADAse synthesis, and so does the addition of glutathione to the incubation medium. These agents must have different sites of action, since irradiation antagonizes the repressing effect of cinnamic acid, whereas glutathione does not.

Evaluation of doping profiles from capacitance measurements

Abstract: Approximate CV curves are calculated for a number of typical doping profiles near a semiconductor p — n junction. These calculated curves can be used for the evaluation of doping profiles from experimentally determined CV curves. This evaluation of doping profiles from measured CV curves alone is never unambiguous. It is shown that it is often possible to reach a decision regarding the real profile, if additional information concerning the semiconductor material and the process of preparation of the junction is available.

Fracture phenomena and strength properties of chemically and physically strengthened glass: I. General survey of strength and fracture behaviour of strengthened glass

Abstract: One of the methods most frequently used for reinforcing glass objects is to introduce compressive stresses at the surface Such stresses can be produced physically, as in the thermal toughening process, or chemically, by applying a film of a lower coefficient of thermal expansion than the glass body itself, or by producing a compressive surface layer making use of the “ion stuffing” technique The advantages and disadvantages of the different strengthening methods are discussed with relation to the observed strength values (measured either by quasi-static loading or by impact loading) and the fracture behaviour of reinforced glass objects

Fluorescence of Niobium‐Activated Antimonates and an Empirical Criterion for the Occurrence of Luminescence

Abstract: The fluorescence of Nb5+‐activated antimonates is reported A relation has been found between the position of the maximum of the excitation (and absorption) band of the niobate octahedra and the quenching temperature of their fluorescence This result can be explained using a simple configuration‐coordinate diagram The displacement of the equilibrium distance of the excited state relative to the ground state can be estimated from the set of radii derived by Waber and Cromer for the principal maxima in the radial wavefunctions of the elements It is shown that the estimated displacement of the excited state should be 03 A or less to have efficient fluorescence from this state

Crystal structures, magnetic properties and phase relations of erbium-nickel intermetallic compounds

Abstract: The binary system erbium-nickel has been investigated by X-ray diffraction, thermoanalysis and metallography. A constitutional diagram has been constructed. Eleven intermetallic compounds have been identified: Er 3 Ni, Er 5 Ni 3 , ErNi, ErNi 2 , ErNi 3 , Er 2 Ni 7 , ErNi 4 , Er 4 Ni 17 , Er 5 Ni 22 , ErNi 5 and Er 2 Ni 17 . For all compounds the lattice constants have been determined. Crystal structures are given for all the compounds except Er 5 Ni 3 , ErNi 4 , Er 4 Ni 17 and Er 5 Ni 22 . A possible hexagonal structure for the last three compounds is indicated, in which the peculiar stacking along the c -direction leads to extremely large unit cells. The magnetic properties of most of the compounds have been investigated: Er 5 Ni 3 , ErNi, ErNi 2 , ErNi 3 , Er 2 Ni 7 , ErNi 5 and Er 2 Ni 17 are either ferro- or ferrimagnetic; Er 3 Ni is antiferromagnetic.

A general model for junction circulators; choice of magnetization and bias field

Abstract: The properties of nonreciprocal ferrite devices depend strongly on the ferrite properties. The dependence of several device specifications, such as insertion loss, power capability, etc., on, for instance, linewidth, dielectric loss tangent, critical field, etc., is similar for the three different groups of nonreciprocal devices. The dependence of bandwidth and insertion loss on ferrite magnetization and polarization field is specific for a special group. To investigate the latter dependence for junction circulators, a general model for that group of devices is introduced and discussed. Junction circulators consist of a number of identical resonators. These resonators, mutually coupled by means of the ferrite, are connected to the ports. The lumped element circulator is discussed qualitatively and the stripline circulator quantitatively. For the latter, ranges of magnetization and bias field are determined for operation both above and below resonance. Obtainable bandwidths are estimated.

Hall mobility of electrons in the space-charge layer of thin film CdSe transistors

Abstract: Field- and Hall-effect measurements were performed on CdSe polycrystalline films at temperatures between −150 and +90°C. The mobility increased with carrier concentration over two orders of magnitude. This can be explained by the polycrystalline film model. It will be shown that in such a model a relatively small number of traps in the barrier region can have a profound influence on the onset of the enhancement-type field-effect conduction and its temperature dependence.

Darstellung und Kristallstruktur der Phasen „Sn4P3” und „Sn4As3”

Abstract: Die Darstellung, Analyse und einige physikalische Eigenschaften der Phasen “Sn4As3” und “Sn4P3” werden beschrieben Die bereits bekannte Kristallstruktur wird bestatigt und verfeinert (s Tab 1) “Sn4As3” and “Sn4P3” were crystallized from the melt and isolated from the excess of Sn with Hg The soft, silvery and plate-like crystals showed a marked deviation from stoichiometry: Sn380As3 and Sn4P265; these formulae correspond to the content of the rhombohedral unit cell The structure proposed by Hagg and Hybinette was confirmed and refined (see Tab 1) The structure is similar to that of Bi2Te2S (C 33), consisting of packets of 7 layers (instead of 5 in Bi2Te2S) of cubic close packed atoms, layers of Sn and As resp P alternating As each packet begins and ends with Sn layers, the packets are bound by rather weak SnSn bonds, which account for the easy cleaving of the crystals, and which may be a situation analogous to that of (111) surfaces of crystals of the NaCl type covered by a weak adsorbent The distances of the layers are changing in an oscillatory manner from outwards to the middle of a packet (see Tab 3) The electric behaviour seems to be metal-like