2p 312-3d emission and absorption spectra of nickel and cobalt in amorphous metallic Ni-P and Co-P have been studied. No modification of the emission spectrum with respect to the pure crystallised metal is observed. As a consequence, it may be deduced that the 3d filled distribution of both materials is similar. But, differencies appear in the absorption spectrum ; by comparison with an APW calculation of density of states, we can identify the part of the Ni distribution which is involved in this modification. By combinating X-ray and ESCA measurements, we may conclude that there is no shift observed in the position of the Fermi level, when the nickel is amorphised by the presence of about 15 % phosphorus atoms. From our experiments, similar results seem to be observed for the amorphous metallic Co-P. In this paper, w e present a study range explored. The emission spectra are by X-ray spectroscopy of two amorpFous alobtained by electron bombardment of solid loys of a transition metal with a metalloid. target wlth a 45O take off angle and analyX-ray spectroscopy allows the invessed in a direction perpendicular to that of tigation of both filled and empty states the incident electrons : for the absorption with a given angular momentum for each elethe bremsstrahlung of a W target goes ment present in any material. We have apthrough the very thin absorbing sample,then plied it to a study of the density of 3d it is analysd. The s~ectra ilre recorded bv states of N1 and Co in amorphous Ni-P and means of a thin window 3-CH, gss flow proporCo-P, comparatively to those of pure N1 and tional counter placed behind an adjustable Co. For that purpose, we have undertaken sllt. The spectra are scanned by successive the analysis of both emission and absorpsteps along the Rowland circle. The instrution 3 ~ 1 2 ~ ~ ' ~ spectra. In the emission,bemental resolution is about 0,13 eV for nitcause of the transition probabilities, the kel and 0,17 eV for cobalt. 2p3/2 hole 1s preferentially filled by an The Ni-P samples have been chemielectron originating from a 3d level, and cally deposited by means of an oxydo reducin absorption, a 2p3'2 electron is promoted tion in the liquid phase (1). The CO-p Ones up to an empty 3d or 4s level. have been prepared by flash evaporation The experiments have been carried out from a wire onto which an ~lectrol~tic by means of a 500 mm radlus bent crystal deposition of Co-P has been made as descrivacuum high resolution spectrometer. The bed in ref.2 . The depositiowwere made crystals, used in first order reflection onto a copper plate for the emissions or a are a beryl (1070) for nickel and mica 0,5 pm thick aluminum screen for the ab(002) for cobalt : they show no anomaly of sorption. In both cases, their thickness the reflected i-ntensjty in the spectral was between 50 and 100 nm. The concentraArticle published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19808106 C8-428 JOURNAL DE PHYSIQUE tion of P in h7i-P and Co-P are near the eutectic: that is abcut 15 and 19 aton-ic mercent res~ectivel.~. Tui-D most of tho P atom are the centre OF icosahe3ral Ni clusters an3 only a few ?ercent of the ?toms are randovlv 6istributed. In Co-P, the structure seems to be constituted by clusters of 9 atoms of Co surrounding one P, 3 or 4 atoms being closer to the P atom (3). In pure cobalt samples prepared by evaporation, two allotropies forms are present : malnly with hcp and a few percent of FCC structures. XPS experiments Pave been performed on the same samples in order to determrne the bindinq energy of the inner 2p3/21evel. The apparatus we used is an > E L 200 R Instrument wbose resolution was about 1,2 eV in our experiments. The results we have obtaine2 by X-ray spectroscopy for Ni-P Pave been partly described elsewhere ( V . Let us notice that we have observed no shape modificatlon and no shift of the emission curve between tb.e nickel in amorphcuc Nip and the pure metal. On the contrary, sone changes appear in the absorption snectrun . The N1 absorption curve consists principally of a line A and an absorption jump followed by a feature B at about 6eV towards higher energies relative to A. From an APW calculation performed for fcc paramagnetic hli ~ p ~ / ~ absorption taprng into account tbe broadening due to the inner level ( 5 ) , it 1s possible to attribute A and B respectively to transitions towards pure 3d and d-s bands. For Ni-P, the principal line A is shifted towards higher energies and the feature B is considerably srroothed out. Foreover, we have measured by XPS the energy of the Ni 2p 3/2 level in both metallic and amorphous Ni 7 within + the precision of tke experiment ( 0,ZeV) no shift was observed. So we assume that in Ni-P the shift of the principal maximum of A 1s attribuable to a shift of nickel pure 3d unoccuoied statesat the threshold, and the modification in B, to a modification of d and also s states at about 6 eV above

In order to reduce residual differences between measured values of the direct beam and values estimated from the coefficients sigma and K-t when a single annual correlation expression is used, we have divided the year into three periods according to the sunset hour angle, omega(s) at our site : winter; spring/autumn; and summer. Expressions of correlation have been derived for each of these three periods. Use of three seasonal expressions gives a more accurate estimate than does a single annual expression.

The crystallization properties of electrodeposited amorphous alloys Co1-xPx (enthalpy of crystallization, shape of the DSC thermopower signal. X-ray diffraction, resistivity) show that a local chemical order exists in these phases. This local chemical order at the eutectic composition implies the existence of a double miscibility gap in the metastable liquid equilibrium diagram. This work shows the relaxation effect in the amorphous state for all concentrations other than the eutectic composition. This relaxation effect should be interpreted as the recovery of the system, which tends to return to the demixed metastable liquid phase.

The effects of thermal treatment on the conductivity and the temperature coefficient of resistivity of thin amorphous layers of Ni-B metallic glasses (66% Ni, 34% B) are analysed in terms of the dependence on thickness and ageing temperature. The layer exhibits a macroscopical structure consisting of clusters in an amorphous medium; it is assumed that the cluster resistivity is temperature independent up to 350° C and that the amorphous medium is altered markedly by the ageing processes. These consequences are deduced which are in agreement with a previously proposed model for a layer structure.

The preparation by oxide-reduction in liquid phase and electrolysis of amorphous alloys of nickel-phosphorous is examined. They take the form of films deposited on glass, powder and thick layers formed on copper foils. Their composition and some of their characteristics such as local order, crystallization, electrical and magnetic properties are measured.

The influence of various annealings on the magnetization of a partially disordered Ni 91 P 9 alloy has been investigated. The magnetic moment σ* 0,0 and the Curie temperature T c are found to vary linearly with the annealing temperature T a up to T a =523 K and the alloy behaves like a weak ferromagnet. With T a >573 K, the (200) reflexion of the f.c.c. nickel appears in the X-ray patterns and a sharp increase in T c and σ* 0,0 is observed. These results agree with previous thermomagnetic data which showed the alloy to be completely crystallized in a mixture of pure nickel and Ni 3 P alloy after heating to T a =773 K. Anomalous thermal variation of the magnetization is observed below 50 K, as previously observed by other researchers Influence de differents recuits sur l'aimantation d'un alliage partiellement desordonne Ni 91 P 9 . Le moment magnetique et la temperature de Curie T c varient lineairement avec la temperature de recuit T a , jusqu'a T a =523 K et le comportement reste celui d'un ferromagnetique faible. Lorsque T a devient egale ou superieure a 573 K on observe sur les diagrammes de rayons X la raie (200) du nickel ainsi qu'une brusque augmentation du moment magnetique et de T c

Afin d'utiliser dans les meilleures conditions le couple chlorure de calcium-ammoniac en vue de la réfrigération solaire ou du stockage d'énergie, nous examinons l'effet néfaste de l'eau sur ce binaire.La loi donnant la variation du gonflement que subit le sel en absorbant l'ammoniac jusqu'à saturation complète est indiquée.Nous en déduisons qu'il faut prévoir pour le générateur en volume libre de 4 litres environ pour chaque kilogramme de sel pur.Enfin, nous précisons les vitesses d'absorption et de désorption de NH3.Cette étude montre que plus on se rapproche de l'octoammoniacate, plus la vitesse de formation des complexes est faible.Abstract.2014 In order to use the couple calcium chloride-ammonia in the best conditions for the solar refrigeration or energy stockage, we show the bad effect of the water on the binary.The law giving the variation of the swelling of the salt absorbing ammonia till complete saturation is indicated.We deduce from this that we have to foresee for the generator a free volume of about 4 liters per kilo of pure salt.Finally we specify the absorption and desorption rates of ammonia.This study shows that the closer we are to the neighbourhood of the octoammoniacate, the lower is the complex formation rate.

2014 Nous avons effectué des mesures d'aimantation sur des alliages amorphes Co1 -x Bx préparés par voie chimique et électrolytique, de concentration 0,20 ~ x ~ 0,32, et avons examiné l'influence sur les mesures du mode de préparation, de la concentration en métalloïde, et de la température de recuit.Abstract.2014 We have measured the magnetization on amorphous alloys Co1 -xBx prepared by chemical and electro- lytical ways.Their concentrations in x are 0.20 ~ x ~ 0.32.We examine the influence of the preparation mode, the metalloid concentration and the annealing temperature on the data.

Experimental data related to the variations with temperature in the film resistivity of amorphous nickel-boron layers (electrochemically deposited) and its temperature coefficient are used for identifying the temperature for the phase transition. Suggestions are presented for interpreting the observed shifts in the resistivity and in the product of resistivity and its temperature coefficient.

Dans le but d'augmenter le rendement des capteurs plans à air, nous proposons l'emploi de surfaces absorbantes en forme de jalousie, composées de d

2014 Après un an d'essais systématiques au laboratoire, nous exposons les premiers résultats relatifs à la thermocinétique d'une installation frigorifique solaire à absorption solide utilisant le couple (CaCl2-NH3) utili- sable en zone tropicale.L'énergie solaire est simulée par un ensemble de spots lumineux très faiblement divergents et délivrant une puissance constante de 1 kW.m-2.Nous décrivons, durant le fonctionnement de l'appareil, l'évolution des paramètres physiques des trois organes principaux qui le composent : absorbeur + générateur, condenseur et évaporateur.Nous en déduisons que la température d'ébullition de l'ammoniac dans l'évaporateur suit une loi de la forme 03B8évap = 03B1e-t/03C4 + b.Abstract.2014 After one year of systematic tests in the laboratory, we present the first results relative to the thermo- kinetics of a solar frigorific installation with solid absorption using the couple (CaCl2, NH3) adapted to a tropical zone.The solar energy is simulated by one light spots battery very weakly divergent and giving a constant power of 1 kW.m-2.During the functionning of the apparatus, we observe the evolution of the physical parameters of the three principal organs which form it : generatar-absorber, condensor and evaporator.We deduce the ammonia boiling temperature in the evaporator follows a law of the form 03B8evap = 03B1 e-t/03C4 + b.

Après un an d'essais systématiques au laboratoire, nous exposons les premiers résultats relatifs à la thermocinétique d'une installation frig

We confirm the hypothesis of clustering and local chemical order in the amorphous metal-metalloid alloys prepared by oxido-reduction. We propose two types of structure in good agreement with respect to two types of amorphous—crystal transitions observed in the Ni77P23 and Ni66B34 alloys.

Amorphous alloys, generally obtained by splat cooling condensation on a cold support or sputtering, were prepared in our laboratory at ambient temperature by two other methods. The first one, the oxidoreduction in liquid phase, gives films, the thickness of which is 500 to 2000 A, deposited on an isolating support — glas, plastic or ceramic. The second one, electrolysis of adapted solutions, allows us to obtain some thick layers the thickness of which is in this case, 1 to 100 microns. The support is a conductor, for example, a copper leaf.

Experimental data related to the resistivity of chemically deposited silver films, and the TCR are interpreted from linearized equations in the framework of the three-dimensional conduction model. The electronic transmission coefficient at the grain boundary, t, and the electronic specular reflection coefficient at the film surface, p, are calculated from both resistivity and TCR measurements; no marked departure is observed. The high value of f agrees with crystallographic data.