J. D. Fast

1965, No. 3

Nitrogen

81

.In silicon iron

546.17 :621.318.13

Professor Fast has been afrequent contributor to our journal. The article below is a chapterfrom part Iof his recently published book "Interaction of metals and gases" [*l. This chapterdeals with methods of bringing about in silicon iron a special crystal orientation which givesthe material favourable magnetic properties. New insight was obtained from experimentscarried out by the author - about ten years ago - in which he added for the above men-tioned purpose small quantities of a second phase to the metal. His experiments gavethe impetus to "extenstve investigations in various countries, which have led among otherthings to better control of the production of grain-oriented silicon steel, used for makingtransformer cores.

Introduetion

Nitrogen can play an important part in silicon steelthat is used as the "iron" core of transformers, electricmotors and electric generators. The steel which is usedin transformers generally contains about 3% silicon.In the earliest transformers the core was made from

unalloyed steel which was soft-annealed to make it asfar as possible free of internal stresses. The coercivityand hysteresis losses in this material were relativelylarge as a result of the many inclusions it contained,especially inclu~ions of iron carbide. Also the eddycurrent losses were relatively high due to the smallelectrical resistivity. It was especially unfortunate thatthe coercivity and hysteresis losses spontaneously in-creased with the course oftime. This "magnetic ageing"was caused by the slow precipitation of nitrogen in theform of iron nitride [ll.

The silicon steel used in transformers suffers smallereddy current losses than unalloyed steel due to itsgreater resistivity. Also the hysteresis losses are smallerbecause silicon encourages the formation of graphitewhich is magnetically less harmful than iron carbide,since for the same number of carbon atoms the totalvolume of inclusions is much smaller. It is also of im-portance that silicon steel exhibits no ageing phenom-ena because the nitrogen which is present as an im-purity occurs, after a suitable annealing treatment, in theform of a very stable silicon nitride [2l. The compositionofthis nitride is SiaN4 [3l. However, this precipitate toomust be considered undesirable since, like all other pre-

Prof. Dr. J. D. Fast is a research worker at Philips ResearchLaboratories, Eindhoven, and a Professor Extraordinary ofPhysical Chemistry at the Technical University, Eindhoven.On 9th January 1965 Prof. Fast received from the TechnicalUniversity of Delft the degree of Doctor honoris causa "for hisoutstanding services in the field of scientific and technical researchon metals".

cipitates, it has an unfavourable effect on the coercivityand the hysteresis losses. In the following, however,we shall see that by the deliberate addition of nitrogento silicon steel one can profit from the presence of thiselement to obtain a magnetically favourable crystal ori-entation.

The role of Si3N4 in making grain-oriented silicon steelsheet

.Until comparatively recently virtuallyall the siliconiron sheet for transformers was obtained by hot -rollingThe directions of easy magnetization, <100>, of theseparate crystals in the sheet are then almost randomlydistributed over the various directions in space (fig. 1),so that the hysteresis losses are relatively large. Inprinciple it would be most desirable to make the cores

Fig. 1. The figure shows schematically that in hot-rolled siliconsteel sheet the crystals show no preferential orientation with res-pect to the plane and direction of rolling.

[*J J. D. Fast, Interaction of metals and gases I, published byPhilips Technical Library, Eindhoven, and Academic Press,New York, 1965. '[IJ J. D. Fast, Philips tech. Rev. 13, 165, 1951/52; J. D. Fast andL. J. Dijkstra, Philips tech. Rev.13, 172, 1951/52.[2J J. D. Fast, Philips tech. Rev. 16, 341, 1954/55.[3J W. C. Leslie, K. G. Carroll and R. M. Fisher, Trans. AIME194,204, 1952; H. A. Sloman, J. Iron Steel Inst. 182, 307, 1956.

82 PHILlPS TECHNICAL REVIEW VOLUME 26

from large laminar single crystals (bounded by cubefaces) in such a way that the magnetic flux always fol-lows a direction of easy magnetization (fig. 2).

[010]-~F:::. v-r::: v

b --fao] r.:: '-~ [100b v-v-r.::b /<,

- -- "t---..--[010]

Fig. 2. Symbolic representation of a transformer, the core ofwhich is built up of single crystal sheets in such a way that the'magnetic flux can everywhere follow a direction of easy magneti-zation, a <100> direction.

Technically it is impossible to make single crystalsheet in large quantities. But it has been found possibleto make on a large scale (in quantities of thousands oftons each month) polycrystaIIine silicon iron sheet, inwhich all the crystals have nearly the same orientation(fig. 3). This orientation is such that the crystals liewith a (110) plane approximately parallel to the surfaceof the sheet and with a [001] direction, a direction of

Fig. 3. Schematic representation of the crystals of cold-rolled3% silicon iron sheet in which all the crystals have about thesame orientation, viz. the orientation (110)[001] (cf. fig. 4).

easy magnetization, approximately parallel to the direc-tion of roIling (fig. 4). This texture is often referredto as Goss texture after its inventor, Goss, but alsoas (110)[001] or cube-on-edge texture [4]. The lattername is illustrated by fig. 5, in which the orientationunder discussion is demonstrated with the help of anumber of cubes, which symbolize the unit cells. TheGoss texture is obtained by cold-rolling silicon ironfrom a certain thickness and by subjecting it to certainheat-treatments.For many years the way in which the crystal orienta-

tion in the Goss sheet is brought about was not under-

stood and the production of the sheet did not alwaysgive the desired results. Our own experiments showed

. that it is impossible to obtain the Goss texture in siliconiron sheet made from pure iron and transistor-qualitysilicon. From this we concluded that the presence of im-purities in the material is of essential importance [5].

In further experiments we added measured quantities,in each case of one element, to pure silicon iron alloys.

[001]

Fig. 4. In silicon iron sheet having Goss texture the crystals areoriented in such a way that they lie with a (110) plane approxi-mately parallel to the rolling plane and with a [001] axis (cubeaxis) approximately parallel to the direction of rolling (cf. fig. 5).

It was found that the desired texture is readily ob-tained by introducing nitrogen (in quantities of a fewhundredths of a percent) and heat-treating the metalbefore cold-rolling in such a way that it contains afinely divided precipitate of SÏ3N4, which is mainlypresent at the grain boundaries [61. Fig.6 shows anelectron microscopie photograph of 3% silicon iron,in which a precipitate of this type is present.After cold-rolling and after primary recrystaIlization

at 6000 to 800oe, both the pure silicon iron sheet and

Fig. 5. Schematic representation of the crystal orientation inmagnetic steel with Goss texture (cube-on-edge texture). Thearrow indicates the direction of rolling.

1965, No. 3 NITROGEN IN SiLiCON IRON 83

the sheet containing Si3N4 contain only very few crys-tals with the orientation (110)[001]. In the pure alloythe primary recrystallization is followed at high tem-perature (e.g. 900 "C) by normal grain growth whichexhibits no preference for a particular orientation. Tnsilicon iron containing nitrogen the normal grain growthis inhibited by the Si3N4 precipitate. If the metal isheated in the appropriate ternperature range in pure

As soon as the (110)[001] crystals have a sufficientstart in size on the other crystals, the temperature canbe raised to accelerate further growth.

The Si3N4 particles, which are so useful for produc-ing the Goss texture, are unfavourable for the finalmagnetic characteristics of the material. They musttherefore be removed from the silicon iron after theyhave accomplished their grain-growth function.

Fig. 6. Electron micrograph of 3% silicon iron in which a precipitate of Si3N4 is presentalong the grain boundaries. The micrograph corresponds to an area of 17 x 19 microns.

hydrogen these inhibiting inclusions slowly coagulateand go into solution, and at a certain point the fewfavourably oriented crystals begin to grow but not, asyet, the others. ln order words secondary recrystalliza-tion (exaggerated grain growth) occurs, by means ofwhich a few primary crystals with orientation (110)[001]grow at the cost of the other crystals to many timesthe sheet thickness. The driving force for growth ofof these grains is the low gas-metal interfacial energyof the (110) surfaces in an atmosphere of pure hydro-gen [71. This surface energy is less than that of any (hkl)plane different from (lI0).The selective grain growth under discussion occurs

in a particular temperature range. If the nitrogen-bear-ing silicon iron is heated immediately before or afterthe primary recrystallization at too high a tempera-ture (e.g. 1250 dc), then the active inclusions dissolvevery rapidly, so that one obtains mainly normal graingrowth, which results in a poor texture. Therefore onemust first heat at a lower temperature (900 0-1000 "C).

This takes place automatically in the final heat-treat-ment in an atmosphere of pure hydrogen, since virtu-ally all the nitrogen then leaves the metal [5][81.

In the commercial 3% Si-Fe alloys, MnS is the mostimportant impurity inhibiting normal grain growth afterprimary recrystallization [91. Various other inclusionscan also perform this task [lOl. Here again it is of pri-mary importance that they be present in the metal in

14] N. P. Goss, Trans. Amer. Soc. Met. 23, 511, 1935; R. M.Bozorth, Trans. Amer. Soc. Met. 23,1107, 1935; C. G. Dunn,Cold working of metals, Amer. Soc. for Metals, Cleveland 1949,pp. 113-120.15J J. D. Fast, Philips Res. Repts. 11, 490, 1956.[6J See also: J. D. Fast and J. J. de Jong, J. Phys. Radium 20,371,1959.L7J J. E. May and D. Turnbull, Trans. AIME 212, 769, 1958;J. L. Waiter and C. G. Dunn, Trans. AI ME 215,465, 1959 and218, 1033, 1960.[8J J. D. Fast and H. A. C. M. Bruning, Z. Elektrochemie 63,765, 1959.[9J See the first article mentioned in note [7J.

[tOj H. C. Fiedler, Trans. Al ME 221, 1201,1961; M. J. Markusze-wicz, J. Tron Steel Inst. 200, 223, 1962.

84 PHILIPS TECHNICAL REVIEW VOLUME 26

the desired size and distribution. For inclusions ofMnS this has been shown most convincingly [11] byFiedler. He experimented with a 3.3% silicon ironalloy which contained a little less than 0.1% MnS. Thiscompound could be completely dissolved by heatingthe metal at 1325°C. The most effective degree of dis-persion could then be obtained in two ways: (a) bycorrect choice ofthe cooling rate, (b)by drastic quench-ing followed by precipitation heating at a lower tem-perature (1000 0C)., An advantage of SiaN4 over other grain-growth in-'hibitors is that after the final heat-treatment no im-purities remain behind in the metal, so that the mag-netic properties are particularly good.The characteristics of silicon iron sheet with Goss

texture deviate in some respects very little from thoseof single crystals. A disadvantage, however, is that theunfavourable [110] directions of the crystals lie in adirection perpendicular to the direction of rolling(cf. fig. 4). One can therefore only take full advantage ofthis material if the magnetic flux is everywhere parallelto the direction of rolling, i.e. ifit is used in the formof ring cores wound from sheet and not, for example,in the form of E sheets.For many applications it would be very desirable to

have available silicon iron sheet with cube texture [12],

i.e. sheet in which the crystals are so oriented that notonly the direction of rolling, but also the direction pe~-pendicular to it is a direction of easy magnetization«100)[001] texture,jig. 7). In Germany and the U.S.A.research workers have already succeeded in makingthis material with (100)[001] texture on a small scale.In the production, the interaction between the metalsurface and the surrounding gas atmosphere plays avery important part. If the oxygen activity of the gasexceeds a particular value, then it is no longer the (110)planes but the (100) planes which have a smaller sur-face energy than all other (hkl) planes, in other words,the driving force for growth of (100) grains is thengreater than that of (110) grains.A convincing demonstràtion of the above is given by

expériments of WaIter and Dunn [13] 'on the migrationof (100)/(110) boundaries, i.e. boundaries between twograins, one ofwhich has a (100) plane and the other a(110) plane parallel to the surface of the 3% siliconiron sheet. At 1200oe the (100)/(110) boundaries ad-vance into (100) grains in a good vaèuum, then reverse

[11] H. C. Fiedler, Trans. ArME 230,95,1964 (No. I).,[12] F. Assmus, R. Boil, D. Ganz and F. Pfeifer, Z. MetalIk. 48,341, 1957; F. Assmus, K. Detert and G. Ibe, Z. MetalIk. 48, 344,1957; J. L.Waiter, W. R. Hibbard, H. C. Fiedler, H. E. Grenob-le, R. H. Pry and P. G. Frischmann, J. appl. Phys. 29, 363,1958; G. Wiener, P. A. Albert, R. H. Trapp and M. F. Littmann,J. appl. Phys, 29, 366, 1958.[13] J. L. Waiter and C. G. Dunn, Acta metallurgica 8, 497,1960.

their direction and migrate into (110) grains in an. at-mosphere of impure argon. The direction of migrationreverses once again with (110) grains growing at theexpense of (100) grains in a second vacuum anneal.These results are explained by the authors in terms of achange in concentration of oxygen atoms at the gas-

Fig. 7. Schematic representation of the cube texture (cf. fig. 5).The arrow indicates the direction of rolling.

metal interface during the anneals. The addition of oxy-gen atoms to the surface during the anneals in impureargon results in a decrease of the specific surface energyof the (100) oriented grains to a value lower than thatof the (110) oriented grains. In a good vacuum or inpure hydrogen, however, the 'oxygen concentration atthe surface is lowered to the point where the surfaceenergy of the (110) grains has the lowest value.The development of the cube tex ture in 3% silicon

iron is, however, much more difficult and complicatedthan would be supposed from the foregoing. Controlof the gas atmosphere in the final heat treatment is anecessary, but not sufficient condition for success. Upto now it has not been found possible to produce sili-con iron sheet with cube texture economically in largequantities. The main difficulty seems to be getting thealloy into such a condition that, after primary recrystal-lization of the sheet, there is a sufficient number ofcrystals present with the required (100)[001] orientation.According to patents of the General Electric Company(U.S.A.) this aim can be achieved by starting with in-gots having favourably oriented columnar crystals ob-tained by controlled directional solidification.

Summary. The article is a chapter from part! ofthe author's recent-ly published book "Interaction ofmetals and gases". The chapterdeals with the influence of nitrogen on crystal orientation and theassociated magnetic properties of cold-rolled and recrystallizedsilicon iron, which is generally used for transformer cores. Giventhe right conditions, Si3N4 precipitates as a finely divided secondphase which promotes the growth of crystals with a (110)[001]orientation ("cube-on-edge texture"). The MnS present in com-mercial types of silicon steel fulfils a function similar to that ofSiaN4. Mention is also made of experiments aimed at producingsilicon iron with a (100)[001] orientation ("cube texture"), whichwould be even better suited for the same purpose.

1965, No. 3 85

Glass fracture surface

Fracture surface of a fragment of glass from atelevision picture tube, taken with the electron mi-croscope a few hours after fracture. Magnificationapprox. 20000 x. Within about an hour of fracture,

traces of chemical attack are visible: they are prob-ably local swellings caused by the action of water(layers of silica gel). After a few hours a kind of frost-work tracery as seen in the photograph often appears.

86 PHILIPS TECHNICAL REVIEW VOLUME26

Recent scientific publications by the staff ofthe Philips laboratories and factories

Reprints of those papers not marked with an asterisk * can be obtained free of charge fromthe Philips Research Laboratories, Eindhoven, Netherlands, where a limited number of re-prints are available for distribution. Requests need only quote the reprint number given initalics at the end of each entry.

P. Beekenkamp.and J. M. Stevels: The structure ofsome glasses of the composition MIIIMv04.Phys. Chem. Glasses 4, 229-233, 1963 (No. 6). 3319

H. Bienfait: Externe en interne communicatie bij hetonderzoek. (External and internal communication inresearch; in Dutch.)Meded. Dir. Tuinb. 26, 542-551, 1963 (No. 10). 3322

G. Blasse: New types of cation-order in the rocksaltlattice: the structure of Li3Sb04 and LhNb04.Z. anorg. allgem. Chemie 326, 44-46, 1963 (No. 1/2).

3313G. Blasse and D. J. Schipper: Antiferromagnetism ofCoRh204 and NiRh204.Physics Letters 5, 300, 1963 (No. 5). 3293

P. B. Braun and J. A. Goedkoop: An X-ray andneutron-diffraction investigation of the magnetic phaseAlo.89Mnl.n.Acta crystall. 16, 737-740, 1963 (No. 8). 3285

H. Breimer: The influence of main- and vestigial-side-band widths on picture quality.LE.E. Conf. Rep. Series No. 5 (Television Engineer-ing), 1962, pp. 5-11, published 1963. 3279

H. Bremmer: Scattering by a perturbed continuum.Symp. on electromagnetic theory and antennas, Copen-hagen 1962, pp. 665-699, Pergamon Press, Oxford 1963.

3298A. Bril and W. van Meurs-Hoekstra: Verwendung vonBeugungsgittern in kleinen Spiegelmonochromatoren.Z. Instrumentenk. 71, 232-234, 1963 (No. 8). 3297

C. M. van der Burgt and H. S. J. PijIs: Motional posi-tive feedback systems for ultrasonic power generators.IEEE Trans. on Ultrasonics Engng. UE-10, 2-19, 1963(No. I). 3291

C. M. van der Burgt and A. L. Stuijts: Developments in .ferrite ceramics with strong piezomagnetic coupling.Ultrasonics 1, 199-210, Oct./Dec. 1963. 3303

H. B. G. Casimir: Reciprocity theorems and irreversi-ble processes.Proc. IEEE 51, 1570-1573, 1963 (No. 11). .3317

E."H. P. Cordfunke and A. A. van der Giessen: Pseudo-morphic decomposition of uranium peroxide into U03.J. inorg. nucl. Chem. 25, 553-555, 1963 (No. 5). 3283

J. Dieleman: Paramagnetic resonance of a photosensi-tive centre in CdS :Cu,Ga.Magnetic and electric resonance and relaxation, Proc.XIth ColI. Ampère, Eindhoven 1962, pp. 409-413,North-Holland Publ. Co., Amsterdam 1963. 3289

G. Diemer and B. Bölger: Proposal for reduction ofdiffraction losses in P-N lasers.Physica 29,600-601, 1963 (No. 6). 3287J. van Dijk, V. G. Keizer and H. D. Moed: Synthesis of,B-phenylethylamine derivatives, VIII. Four diastereo-isomers of 1-(4' -hydroxyphenyl)-2-(1 "-methyl-3" -phe-nylpropylamino )propanol.Rec. Trav. chim. Pays-Bas 82, 189-201, 1963 (No. 2).

3284S. Duinker: Basic network elements for the synthesisof non-linear systems.Monograph on radio waves and circuits, ed. S. Silver,pp. 320-329, Elsevier, Amsterdam 1963. 3290P. Eckerlin, J. Maak and A. Rabenau: Über Mischkri-stallbildung in den Systemen (NH4)3AIF6-(NH4)3GaF6und LiAI-LiGa.Z. anorg. allgem. Chemie 327, 143-146, 1964 (No. 3/4).

A93C. FengIer : The reflection of a pulse at an Epstein pro-file.Proc. int. Conf. on the ionosphere, London 1962, pp.400-405, publ. Inst. Phys./Phys. Soc., London 1963.

H30S. Garbe: Desorptionsvorgänge in Ionisationsmano-metern bei Beschuss von ölbedeckten Oberflächen mitlangsamen Elektronen.Vakuum-Technik 12,201-205, 1963 (No. 7). A 83S. Garbe: Desorption experiments in an ultra high vac-uum system, pumped by molecular sieve trapped oildiffusion pumps. .Physik und Technik von Sorptions- und Desorptions-vorgängen bei niederen Drücken, Vorträge 2. Europ.Symp. "Vakuum", Frankfurt/M, 1963, pp. 295-304,publ. 'R. A. Lang, Esch (Taunus). Ä 86S. Garbe: The influence of the gas ambient on theemission properties of oxide-coated cathodes in re-ceiving valves.Suppl. Nuovo Cim. 1, 810-824, 1963 (No. 2). A 94J. A. Geurst: The reciprocity principle in the theory ofmagnetic recording.Proc. IEEE 51,1573-1577,1963 (No. 11). 3316W. van GooI: Vapour pressure measurements of Cdand Cd-Ag alloys at 950°C.Proc. Kon. Ned. Akad. Wet. B 66, 209-215, 1963(No. 4). 3299W. van GooI: Theoretical considerations about thedetermination of the structure of lattice defects byphase equilibria. .Proc. Kon. Ned. Akad. Wet. B 66, 311-331, 1963(No. 5). 3306

1965, No. 3 RECENT SCIENTIFIC PUBLICATIONS 87

W. J. A. Goossens and H. J. G. Meyer: Enkele basis-begrippen uit de fysica van halfgeleiders, I1, lIl.(Some basic concepts of semiconductor physics; inDutch.)Ned. T. Natuurk. 29, 387-399 and 409-418, 1963 (Nos.10 and 11). 3309 and 3315(Sequel to 3025.)

D. Gossel: Multivibratorschaltungen mit Transistorenfür extrem grosse kontinuierlich steuerbareFrequenz-

. variation. .Nachrichtentechn. Z. 15, 5n-525, 1962 (No. 10).

H28

H. G. Grimmeiss and H. Scholz: Efficiency ofrecombi-nation radiation in GaP.Physics Letters 8, 233-235, 1964 (No. 4). A 88

R. Groth and E. Kauer: Lichterzeugung mittels ther-miseher Selektivstrahler.Z. angew. Phys. 16, 130-143, 1963 (No. 2). A 78See also Philips tech. Rev. 26, 33-47, 1965 (No. 2).

J. Haantjes: Pick-up and display tubes for colour tele-vision.I.E.E. Conf. Rep. Series No. 5 (Television Engineer-ing), 1962, pp. 55-58, published 1963. 3280

N. Hansen: Gettereigenschaften von nichtverdampftenGettern mit Porendiffusion und Chemisorption.Vakuum-Technik 12,167-173,1963 (No. 6). A 79

N. Hansen: Non-evaporating getters with surface ad-sorption and pore diffusion.Suppl. Nuovo Cim. 1, 627-640, 1963 (No. 2). A 92,N. Hansen and W. Littmann: Änderung des Hall-effekts bei der ChemisorptionanaufgedampftenMetall-filmen.Ber. Bunsenges. phys. Chemie 67, 970-975, 1963 (No.9/10). A 90

G. E. G. Hardeman: Electron and nuclear spin reso-nance in n-type silicon carbide.J. Phys. Chem. Solids 24, 1223-1231, 1963 (No. 10).

3296

P. A. H. Hart: Interception, scattering and multi-velocityeffects in a transverse-wave electron beam.Microwaves, Proc. 4th int. congress on microwavetubes, Scheveningen 1962, pp. 222-227, publ. Centrex,Eindhoven 1963. 3327

H. U. Harten and R. Memming: Potential distributionat the germanium electrolyte interface.Physics Letters 3, 95-96, 1962 (No. 2). H 25

J. Hornstra: Dislocations in spinels and related struc-tures.Materials Sci. Res. 1, 88-97, 1963. 3300

B. B. van Jperen: Experimental CW klystron for multi-plication from 30 to 2.5 millimeters.Proc. IEEE 51,935-937, 1963 (No. 6). 3286

M. H. Jergensen, N. J. Meyer and K. J. Schmidt-Tiede-mann: Conductivity anisotropy of warm and hot elec-trons in silicon and germanium.Solid State Comm. 1,226-233, 1963 (No. 7). H 33

E. Kauer: Optical and electrical properties of LaBo.Physics Letters 7,171-173, 1963 (No. 3). A 82

A. Klopfer: Effect of an electric discharge on the ratesof adsorption on titanium of nitrogen and carbonmonoxide.Vorträge 2. Europ. Symp. "Vakuum" (see S. GarbeA 86), pp. 271-277. A 91

M. Koedam, A. A. Kruithof and J. Riemens: Energybalance of the low-pressure mercury-argon positivecolumn.Physica 29, 565-584, 1963 (No. 5). 3281

J. A. Kok, J. W. Poll and C. E. G. M. M. van Vroon-hoven: Breakdown tests carried out on liquefied gases.Appl. sci. Res. BlO, 257-268, 1963 (No. 3/4). 3305

H. de Lang and G. Bouwhuis: A gas laser with a non-degenerate configuration of three plane mirrors.Physics Letters 5, 48-50, 1963 (No. I). 3276

H. de Lang and G. Bouwhuis: Experimental analysis ofZeeman polarisation effects in the output of a He-Nelaser.Physics Letters 7, 29-30, 1963 (No. I). 3301

J. J. van Loef and P. J. M. Franssen: The Mössbauereffect in the hexagonal ferrite BaO.6Fe20a.Physics Letters 7, 225-226, 1963 (No. 4). 3304

B. Lopes Cardozo and F. F. Leopold: Human codetransmission. Letters and digits compared on thebasis of immediate memory error rates.Ergonomics 6, 133-141, 1963 (No. 2). 3278

J. L. Meijering: Usefulness of a lJy plot in the theoryof thermal etching.Acta metallurgica 11, 847-849, 1963 (No. 8). 3292

R. Memming: Surface recombination at higher injec-tion levels.Surface Sci. 1,88-101, 1964 (No. I). H 31

R. Memming: Formation of fast surface states by cu-pric ions at the germanium-electrolyte interface.Physics Letters 7, 89-90, 1963 (No. 2). H 38

L. Merten : Modell einer Schraubenversetzung inpiezoelektrischen Kristallen, I. Allgemeine Theorie -Elektrisches Feld bei Ladungsfreiheit - Ladungsver-teilung bei Feldfreiheit; II. Elektrisches Feld und La-dungsverteilung für eine Versetzung in einem Eigen-hal blei ter im thermischen Gleichgewicht.Physik kondens. Materie 2, 53-65 and 66-79, 1964(No. I). A 89

B. J. Mulder and J. de Jonge: On the sensitization ofthe photoconduction of anthracene by organic dyes.Proc. Kon. Ned. Akad. Wet. B 66, 303-310, 1963(No. 5). 3307

D. J. van Ooijen and W. F. Druyvesteyn: Analogon ofBarkhausen noise observed in a superconductor.Physics Letters 6, 30-31, 1963 (No. I). 3294

H. P. Peloschek: Square loop ferrites and their applica-tions.Progress in dielectrics 5,' 37-93, 1963. 3282

88 PHILIPS TECHNICAL REVIEW VOLUME26

G. H. Plantinga: Pulsed magnetrons for 4 and 2.5 mmwavelength.Proc. 4th int. congress .on microwave tubes (seeP. A. H. Hart 3327), pp. 202-205. 3326See also Philips tech. Rev. 25,217-226, 1963/64 (No. 9).G. Prast: A Philips gas refrigerating machine for 20 "K.Cryogenics 3, 156-160, 1963 (No. 3).· 3324See also Philips tech Rev. 26, 1-11, 1965 (No. I).

S. C. Rademaker and H. J. de Rouw: Quelques possi-biIités d'identification des cordes dans Ie verre.Silicates industr. 28, 541-544, 1963 (No. 12). 3311

H. G. Reik: Optical properties of small polarons in theinfrared.Solid State Comm. 1, 67-71, 1963(No. 3). A 80

H. G. Reik, E. Kauer and P. Gerthsen. Optical prop-erties of lanthanumcobaltite explained by small pola-ran theory.Physics Letters 8,29-30, 1964(No. I). A 85K. J. Schmidt-Tiedemann: Experimentelle Untersu-chungen zumProblem der heissen Elektronen in Halb-leitern.Festkörperprobleme I, pp. 122-174, Vieweg, Bruns-wick 1962. H 26K. J. Schmidt-Tiedemann: Birefringence by free car-riers in semiconductors.Rep. int. Conf. on the physics of semiconductors,Exeter 1962,pp. 191-196, publ. Inst. Phys./Phys. Soc.,London 1962.· H 27S. Scholz: The density-time relation in hot pressing.Planseeber. Pulvermetallurgie 11, 82-84, 1963 (No. 2).

. A84S. Scholz and B. Lersmacher: Der Verdichtungsablaufbeim Drucksintern.Ber. Dtsch. Keram, Ges. 41,98-107, 1964 (No. 2). A 87

.J. A. Schulkes and G. Blasse: Crystallographic andmagnetic properties of the systems lithium ferrite-alu-minate and lithium ferrite-gallate.J. Phys. Chem. Solids 24, 1651-1655,1963 (No. 12).3312

H. Severin: Spinwellen und Spinresonanzen in ferri-magnetischen Oxyden.Festkörperprobleme I, pp. 260-273, Vieweg, Bruns-wick 1962. H 24.H. Severin: Ferrite," chemische Zusammensetzung,Kristallstruktur und Herstellungsverfahren.Sprechsaal für Keramik - Glas - Email 95, 683-688,1962 (No. 24). H 29A. Smit and P. Westerhof: Investigations on sterols,XXI. An alternative .route for the synthesis of some6-dehydro-9,B,lOa-steroid hormone analogues.Rec. Trav. chim.Pays-Bas 82,1107-1114,1963 (No. 11).

3310

Volume 26, 1965, No. 3 pages 61:'88

M. J. Sparnaay: The reaction between water vapor andthe germanium surface.Ann. New York Acad. Sci. 101,973-982, 1963. 3277

M. J. Sparnaay: The interaction between germaniumand cupric ions in an aqueous solution.Surface Sci. 1, 102-109, 1964 (No. I). 3308

A. Stegherr, P. Eckerlin and F. Wald: Untersuchungder Schnitte Ag2Te-Bi2Te3und Aglsi'I'eg-Pb'Te.Z. Metallk. 54, 598-600, 1963 (No. 10). A 81

J. M. Stevels and J. Volger: Impurity-induced imper-fections and the dielectric properties of quartz crystals.Phys. Chem. Glasses 4, 247-252, 1963(No. 6). 3318

W. A. J. J. Velge and K. J. de Vos: Influence ofmillingupon the magnetic properties of the intermetallic com-pound MnAIGe.J. appl. Phys. 34, 3568-3571, 1963 (No. 12). 3320

A. Venerna: The interaction of gases and solids in prac-tical devices.Vorträge 2. Europ. Symp. "Vakuum" (see S. GarbeA 86), pp. 42-53. 3323

M. T. Vlaardingerbroek and K. R. U. Weimer: Someaspects of the interaction of an electron beam and aplasma.Proc. 4th int. congress on microwave tubes (seeP. A. H. Hart 3327), pp. 322-326. . 3325

J. Volger and C. W. Berghout: Fysische eigenschappenen chemie van harde supergeleiders (supergeleiders vande tweede soort). (Physical properties and chemistryof hard superconductors (superconductors of the sec-ond kind); in Dutch.)Ned. T. Natuurk. 29, 322-330, 1963 (No. 9). 3302

J. H. N. van Vucht, H. A. C. M. Bruning and H. C.Donkersloot: New compounds related to the supercon-ductors V3Ga and Nb3Sn.Physics Letters 7, 297, 1963 (No. 5). 3321

J. S. van Wieringen, Y. Haven and A. Kats: Paramag-netic resonance of colour centres in alpha-quartz con-taining germanium. .Magnetic and electric resonance and relaxation, Proc.XIth ColI. Ampère, Eindhoven 1962, pp. 403-408,North-Holland Pub!. Co., Amsterdam 1963. 3288

J. S. van Wieringen and J. G. Rensen: Influence oflattice imperfections on the paramagnetic resonance ofV2+and Cr3+ in MgO.Paramagnetic resonance, Proc. 1st int. Conf., Jerusa-lem 1962, Part I, pp. 105-112, Academic Press, Ne\XYork 1963. . 3314

A. L. Zijlstra: The viscosity of some silicate glasses inconnection with thermal history.Phys. Chem. Glasses 4, 143-151, 1963 (No. 4). 3295

Published 15th October 1965