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In the frame of the CNES R and T activity related to laser metrology, SAGEIS-CSO is actually developing a new smart interferometric sensor, last to arrive in the “MOUSE” family. In this article, we give at first a brief oversight of the MOUSE interferometric concept as well as its performances for two kinds of applications. Secondly, some interesting other set-ups for space applications are mentioned and finally we present modifications that the system will undergo in order to be compliant with long distance measurements. These different developments point out the ability of the MOUSE/IASI interferometric system to be a powerful metrological instrument for space environment.

In the context of formation flying projects, one of the major points is the required precision on the intersatellites distance and/or relative displacement. According to the mission, these needs are more or less restrictive, leading to the use of fine laser metrology. Thus, for the needs of PEGASE mission – a possible DARWIN in flight demonstration- SAGEIS-CSO has been asked by CNES to design a fine longitudinal sensor able to work at 120 K while performing displacement measurements at a working distance range of 25 to 250 m. Its required performances are a resolution and a precision of 25 nm. This activity succeeds to the MOUSE II system development, which has demonstrated the ability to obtain the required laser metrology using a frequency stabilised laser, a compact and totally passive Michelson type sensor head plus a detection unit for data processing. Optical signals are routed using fibres, allowing the sensor head to be alone in a cryogenic environment. Now, the goal is to obtain a validated prototype at a MQ level by the end of 2007. For that, the laser source will be an update of the flight models made for IASI, using a more powerful DFB diode, pin-to-pin compatible with the previous design, and then giving minor changes. The current regulation was optimized in order not to degrade the narrow diode spectral width. The opto-thermo-mechanical design of the sensor head, in collaboration with AAS, is also under progress, and constitutes the major evolution of the MOUSE II.

This project, realized as part of a CNES/CSO Mesure contract, concerns the study and the industrial realization of a sensor aimed at the relative position control of space telescope mirrors.

Magnetic properties of bulk SrTi 1− x Co x O 3− δ solid solutions (for x from 0 to 0.05), prepared in air as those partially reduced, were studied by following the influence of the dopant concentration and valence. A strong paramagnetic and/or diamagnetic contribution and an extremely weak ferromagnetic contribution maintained up to room temperature is observed for all the studied compositions, including the undoped samples. While the paramagnetic contribution shows a classical evolution with cobalt concentration and valence, the ferromagnetic part of the magnetization seems to be independent of the doping process. While some of the observations can support the assumption of an intrinsic property of the SrTiO 3 matrix, the hypothesis of a ferromagnetism associated to some contamination with external magnetic impurities cannot be completely discarded and will be retained here.

The influence of successive sintering treatments on the structural, magnetic and electric properties of high ordered Sr2FeMoO6 (SFMO) samples belonging to the same starting batch was investigated. The solid-state synthesis conditions influence the microstructure of the samples and the Fe/Mo order. Successive sintering treatments with intermediate grindings improve the saturation magnetization (3.8μB) which became close to the ideal value (4μB) and the low field magnetoresistance (LFMR) as a consequence of microstructural changes. Above the Curie temperature the evolution of effective magnetic moment values depicts the presence of mixed valency states: FeII/MoVI and FeIII/MoV where the contribution of FeII/MoVI configuration is favoured by the enhancement of Fe/Mo order during successive sintering treatments.

This article presents a reliability assessment of aeronautic electronic board using the accelerated test approach. The mission profile used is one defined in FIDES for electronic equipment in aircraft. The reliability function is defined taking into account the different phases of product life (Ground, Taxiing, Flying, Dormant). FIDES describes the environment (thermal and humidity, thermal cycling, mechanical, …) for each phase. The paper presents the different accelerated life models used to take into account all environment. A test plan is proposed to estimate the unknown parameters of accelerated life models. The thermal and humidity and thermal cycling tests have been performed and the data are analyzed. Finally, the reliability function is evaluated.

Magnetite synthesized via three different synthesis routes (coprecipitation process in aqueous media, electrochemical synthesis in presence of complexing agents and solid state reaction at high temperature) has been characterized by X-Ray diffraction, scanning electron microscopy, thermal analysis (TGA), FT-IR and Mossbauer spectroscopies. Although each procedure gave homogeneous magnetite powders, many differences could be seen in the physico-chemical properties of the samples mostly depending on the synthesis conditions. For instance, at least two factors seem to have a huge impact onto the Fe3O4 behaviour: the presence of hydration water molecules and the particle size of the powders since a superparamagnetic behaviour was observed with the thinnest particles, at room temperature, on the Mossbauer spectra via the appearance of line broadening and a pronounced central doublet.

Ultrafine magnetite particles are prepared through an electrochemical process, at room temperature, from an iron-based electrode immersed in an alkaline aqueous medium containing complexing compounds. XRD and chemical analysis indicate that the product is pure magnetite, Fe3O4. The size and morphology of the particles are studied by SEM. The magnetite nanoparticles present a magnetoresistance of almost 3%, at 300 K, under a magnetic field of 1 T. A reactive mechanism for the electrochemical process is proposed.

Single crystal neutron diffraction was used to characterize the structural evolution of electrochemically oxidized La2NiO4+δ crystals as a function of temperature. In order to better describe the disorder of the apical and interstitial oxygen atoms we used the maximum entropy method. There is structural evidence not to attribute a peroxide character between the apical and interstitial oxygen atoms situated in exactly ( 1 4 1 4 1 4 ) of the F4/mmm unit cell. We have also reinvestigated the structural phase transition of stoichiometric La2NiO4 crystals at 74 K. The symmetry changes from Bmab to Pccn and remains orthorhombic down to 5 K.

Studies aimed at the nature of magnetic interactions in Fe and Cr substituted lanthanum deficient manganites, La 0.88 Mn 1− x Fe x O 3 ( x =0–0.15) and La 0.88 Mn 1− y Cr y O 3 ( y =0–0.175) are reported. The oxides order ferromagnetically for the entire range of x - and y -values. A decrease in the Curie temperature T c with increasing substitution is observed for both compounds, but the decrease in T c is large for Fe substitution. A large decrease was also seen in the low-temperature magnetic moment of Fe substituted samples. The data indicate possible ferromagnetic ordering of Cr and antiferromagnetic ordering of Fe moments in the oxides. Ferromagnetic resonance studies indicate (i) strong spin–lattice effects in the paramagnetic state, (ii) valence–exchange effects in the ferromagnetic state, and (iii) possible microscopic inhomogeneities in Cr-substituted samples

High-quality centimetric size single crystals of Sr 14− x Ca x Cu 24 O 41 (0⩽ x ⩽12) have been successfully grown using the travelling solvent floating zone (TSFZ) method associated with an image furnace. We present the growth conditions together with a characterization of the single crystals by means of optical and electron microscopy, EDX, X-ray powder diffraction, Laue X-ray back-reflection and neutron diffraction.

Magnetization, thermoelectric power (TEP), specific heat (Cp), and magnetoresistance (MR) of the as prepared (AP) and oxidized (OX) polycrystalline La0.85MnO3 are reported. Both the samples have rhombohedral symmetry. The magnetization of the OX sample showed a sharper rise as a function of temperature with a Tc∼270 K and a well defined peak of Cp close to Tc. The TEP of the AP sample was positive between 10

We report on the preparation, X-ray diffraction and a.c. susceptibility of Tm0.4Pr0.6Ba2−kSrkCu3O6+z. An orthorhombic to tetragonal transition was observed for k = 0.8. When the samples (for 0 ≤ k

We have compared for the first time the structural and superconducting properties of (A) NdBa2−xPrxCu3O7 and (B) Nd1−uPruBa2Cu3O7. An orthorhombic to tetragonal transition was found in A for x > 0.2 whereas for B no such transition has been reproted. In both cases superconductivity was destroyed for x = 0.3 and u = 0.3 and could be restored by isovalent Sr substitution. However, Ca substitution at the Nd site restored superconductivity only in the case of A. Our results indicate that different mechanisms have to be invoked to account for the suppression of superconductivity in compounds A and B.

La0.85Sr0.15MnO3 single crystals were grown by the floating zone method. They can be reversibly reduced under controlled oxygen partial pressure. Their defect chemistry is investigated together with the evolution of their cell parameters and that of their electric conductivity which is very sensitive to their oxygen content. On the other hand, stoichiometric crystals can be oxidized with a slow kinetics making possible the preparation of diphasic materials.

Single crystals of ${\mathrm{La}}_{0.85}{\mathrm{Sr}}_{0.15}{\mathrm{MnO}}_{3\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ were prepared with various oxygen vacancies from \ensuremath{\delta}=0 to \ensuremath{\delta}=0.055. The $b$ and $c$ lattice parameters were found to increase with \ensuremath{\delta} whereas the $a$ parameter remains practically constant. The oxygen vacancies are expected to reduce the hole concentration, and therefore the Curie temperature and the electrical conductivity. However, these effects are somewhat different from those observed in the hole-doped ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ systems, owing to different lattice distortion. The lattice change of the sample is illustrated by a strong shift in the hyperfine field of ${\mathrm{Mn}}^{4+}$ ions, detected with the NMR method. The oxygen deficiency and all the above properties resulting from it were shown to be reversible.

The authors report on the preparation, X-ray diffraction, ac susceptibility, dc magnetization and thermoelectric power (TEP) of La{sub 1.5}Ca{sub 1.5}Mn{sub 2}O{sub 7}. The compound has a tetragonal structure with lattice parameters a = 3.886(1) {angstrom} and c = 19.34(1) {angstrom}. Magnetic measurements reveal a ferromagnetic transition at around {Tc} = 215 K. TEP measurements indicate hole conductivity and has a maximum at {Tc} indicating an insulator to metal transition. Some possible reasons for the recently reported observation of {Tc} being far above the maximum of resistivity are pointed out.

The structure of glasses prepared in the Na2OGa2O3P2O5 system was investigated by vibrational (IR, Raman) and X-ray absorption spectroscopies. For the orthophosphate compositions, gallium is found in four-fold coordination, whereas it is found in six-fold coordination in a metaphosphate glass. For pyro-, tri and tetraphosphate glasses, gallium atoms are distributed on tetrahedral and octahedral sites. Gallium atoms found on octahedral sites are likely chelated by pyrophosphate groups. The ionic conductivity of the glasses depends mainly on their sodium content.

X-ray absorption measurements in the low (pseudo-rutile) and high (rutile) temperature phases of VO 2 are described. Investigations are made versus temperature and polarization. The analysis of the results leads to conclusions concerning the scattering mechanisms at the origin of the pre-edge, the edge, and the first peak of the edge. Specifically, the angular dependence of the pre-edge of the monoclinic form is different from the rutile form. A new peak on the edge appears for e∥c r at low temperature and the pre-edge and the first peak appears to be sensitive to the asymmetry of the local environment

Coatings have been obtained by deposition of colloidal solutions of VOPO 4 and V 2 O 5 onto a flat substrate. The strong pre-edge anisotropy of these materials reveals a good texturation and organization of these gels even at the molecular scale. Using EXAFS on V 2 O 5 single crystal and VOPO 4 layers, we deduce first that the short axial bond lengths are the same in both compounds, and second that pre-edge can be used even on powders to track any change in axial bonds. Comparing polarized XANES and crystallographic structures, we show that it is a sensitive probe, allowing one to detect weak asymmetries in the ligand coordination sphere. However, the lack of theoretical basis of this effect prevents any quantitative estimate.

The metastable compound SrFe2O4 was prepared by crystallization at 630°C of a glass prepared by melt-spinning. It decomposes above 900°C. It has an orthorhombic unit cell at room temperature with a = 8.031(10) A , b = 18.208(18) A , c = 5.454(6) A , Z = 8, space group Pbc21.

We show unusual dependence of the total electron yield on the illuminated surface orientation of TiO2. This requires care in recording angular dependencies and forces one to use always the same surface orientation. This in fact led us to publish wrong results in the past which we correct here.

Pr substituted at Sm site in SmBa2Cu3O7 did not induce any orthorhombic to tetragonal transition whereas 15% of Pr at Ba site did. Superconductivity was destroyed with 45% of Pr at Sm site or 15% of Pr at Ba site. However, Sr substitution at Ba site in both the cases restored it. Similar data were obtained in the case of Pr in NdBa2Cu3O7. Our data seem to suggest different mechanisms for hole delocalization operate depending on the site occupation of Pr.

We performed magnetisation (M) and transport measurements along the ab plane and the c direction in La2−2xSr1+2xMn2O7 single crystals for x=0.4. In addition to a sharp para-ferromagnetic transition at T c =125 K , a weak maximum in M was found around 265 K. A sharp drop of resistivity at Tc associated with a semi-conductor to metal transition was found for both current orientations. The colossal magnetoresistance of the compound CMR=−(ρH−ρ0)/ρ0 was found to be ∼100% in a field of 8 T near Tc. In contrast with the well-known La1−xSrxMnO3 type manganites, a CMR effect larger than 10% was present at all temperatures ranging between 5 and 300 K.

In La 1.5 Ca 1.5 Mn 2 O 7 , whereas a ferromagnetic transition was observed at T c ∼200 K, the resistivity data revealed a semiconductor–metal transition at 95 K, much lower compared to T c . However, thermoelectric power data indicated a strong decrease in carrier density around T c with no detectable anomaly at 95 K. Magneto resistance −( R H − R 0 / R 0 ) plots taken in H =5 T revealed two maxima one with a value of about 95% at 100 K and another of 30% at 200 K.

Conversely to previously reported data, EXAFS indicate that the AsO distances are similar in LiAsO3 and CaAs2O6. The main features of the XANES spectrum of LiAsO3, except the intense white line, come from single and multiple scatterings on atoms found in a small cluster surrounding the absorbing As atom ( R A ).

Elastic wave travel times have been determined as functions of hydrostatic pressure to 3 GPa for five modes of propagation in synthetic single-crystal wustite Feo.943O by ultrasonic phase comparison. The measured travel times, corrected for transducer-bond phase shifts, constrain very accurately the zero-pressure elastic moduli (GPa) and, for the first time, their first pressure derivatives (dimensionless) as follows: C11∶218.4, dC11/dP∶9.65, C12∶123.0, dC12/dP∶2.77, C44∶45.5, dC44/dP∶−1.03. The zero-pressure moduli are in good agreement with the results of previous determinations by ultrasonic wave propagation but not with all of the moduli determined by resonance techniques. The variation of bulk modulus with pressure calculated from the Cij (P) is extrapolated to much higher pressures via third-order Eulerian isotherms and isentropes based on K0S = 154.9 GPa and (dKs/dP)0T = 4.90. The resulting isothermal and shock compression curves satisfactorily reproduce the experimental data to ∼70 GPa, thereby providing a unified description of essentially all data bearing on the compressibility of wustite. At higher pressures, published shock compression studies provide clear evidence for the existence of a different phase of much greater density and incompressibility. Metallic values of electrical conductivity have been reported for pressures >70 GPa under conditions of shock and high-temperature static loading. Polyhedral face-sharing in either the B8(NiAs) or B2(CsCl) (or derivative) structures would result in shorter Fe-Fe distances, allowing greater 3d orbital overlap conducive to metallic conductivity. However, none of these possibilities satisfactorily accounts for the large inferred increase (14–20%) in zero-pressure density unless the Fe-O distance is also reduced by 3–5% by electron delocalization or spin-pairing. The marked violation of the Cauchy condition associated with the very low value of C44 and its unusual temperature and pressure derivatives are attributable mainly to exchange coupling between nearest and next-nearest neighbor spins.

In Fe3PO7 and FeAsO4-I, the iron (III) is five-fold coordinated with oxygen. The EXAFS spectra of both compounds were recorded at the iron K-edge and analyzed. The spectra of ZnFe2O4 (6-fold coordination), NiFe2O4 (4- and 6-fold coordination) and FePO4 (4-fold coordination) were also recorded for comparison. Parameters of the oxygen back-scattering amplitude and of the FeO phase shift, determined from FePO4, are given. EXAFS makes it possible to determine the Fe-O distances and the iron coordination. Nevertheless, a five-fold coordination cannot be distinguished from a combination of four and six-fold coordinations. Such a distinction can be achieved by XANES.

Oriented lamellar eutectic composites of NiO and ZrO2(CaO) platelets were reduced in CO2/CO gaseous atmospheres to form metallic Ni between the zirconia plates. The relatively rapid longitudinal reduction of NiO is described by a local cell electrochemical model whereby oxide ions are conducted from the Ni/NiO internal reaction front to the external surface through the zirconia electrolyte, while electrons are passed through the Ni product. Both the product morphologies and the reaction kinetics are consistent with the model. Apparent “lateral’reduction of NiO platelets indeed corresponds to longitudinal reduction for a platelet inclined to the external surface. Some plastic deformation of the product zone permits partial accommodation of the volume change upon reduction of NiO to Ni.

Amorphous materials were prepared by the melt-spinning technique in the Fe 2 O 3 SrO system, for the composition 55 Fe 2 O 3 -45 SrO (mol%O) and 50 Fe 2 O 3 -50 SrO (mol%). The glasses were characterized by X-ray diffraction, DTA and magnetic measurements.

The compounds crystallize in cubic perovskite-type system. The space group is Fm 3 m and the cell is entirely ordered. 4 a positions (Wyckoff's notation) contain iron and uranium, 4 b positions, barium and iron, 8 c positions, barium and any holmium, which therefore fills coordinance-12 crystallographic sites. For iron-rich compounds (0 x ⩽ 0.8), interactions between Fe 3+ ions from two magnetic sublattices 4 a and 4 b are antiferromagnetic. The interactions between the third magnetic sublattice, which corresponds to Ho 3+ ions filling 8 c positions, and the resultant of the first two, are slightly ferromagnetic. Such data have been obtained with all the other compounds for which the formula is Ba 3 Fe 2− x Ln x UO 9 , where Ln is Yb, Tm, Er, Dy, Tb, and Gd.

Crystallographic study of compounds with the formula Ba/sub 3/Fe/sub 2 - x/Lu/sub x/UO/sub 9/ (0 less than or equal to x less than or equal to 1.2) shows that they are cubic ordered perovskite-type compounds with probable space group Fm3m. Lutetium is equally distributed between the site of coordination 12 (8c) and the site 4b. On the magnetic point of view, these compounds have the behavior of ferrimagnetic substances. The Neel theory is not applicable to these compounds. The model suggested by Geller et al. for the static magnetic behavior of substituted garnets is most likely to account for the results obtained for these compounds. 3 figures, 2 tables.

We report chemical diffusion coefficient D and effective charge number Z∗ measurements for various deviations from stoichiometry in Fei1−δO and at various temperatures. The results are compared with available data, and correlation factors ⨍ for Fe1−δO are deduced from the comparison of our D values with available self-diffusion coefficients of iron D∗Fe ⨍ is shown to be mostly invariant with temperature and nonstoichiometry. Its value lies in the range 0.54–0.62. The charge of the moving cations is Z ∗ = 2 . These two results indicate that iron diffusion in Fe1−δO is mediated by a vacancy mechanism from octahedral to octahedral positions within regions where the number of first Fe neighbours of a vacancy is much lower than 12.

Single crystals of wustite, Fe1−x o, with x varying between 0.92 and 0.95, have been grown in an arc furnace. The quality and stoichiometry of the crystals are reported.

The elastic constants of Fe 1−x O single crystals have been investigated near the antiferromagnetic phase transition (T N ∼ 198 K) as a function of temperature. The velocity of longitudinal and tranverse ultrasonic waves was measured by the pulse echo overlap method. A strong elastic anomaly occurs for C 44 whereas a small step only is observed for C 11 .

This paper describes the neutron radiography facility associated with the Orphee high flux reactor at the Saclay Nuclear Research Center.

Ultrasonic velocity measurements conducted on Fe1-xO single crystals grown along [100], [110], and [111] have led to the determination of the elastic constants C11 C12, and C44. These constants are in good agreement with values previously calculated from neutron scattering data. There does not seem to be any influence of nonstoichiometry on these constants.