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1.
A new instrument has been set up to study magnetic materials. Curie points measured by means of this simple apparatus are in perfect agreement with those given by a conventional magnetic balance. The apparatus may be used alone, but also combined with an electronic thermodilatometer. Curie points are emphasized simultaneously by the thermodilatometric and impedance curves. It appears that the sensitivity and reliability of the apparatus demonstrate magnetic phenomena of very low intensity such as the order point of α-Fe2O3. 相似文献
2.
K. Ardhaoui J. Rogez A. Ben Chérifa M. Jemal P. Satre 《Journal of Thermal Analysis and Calorimetry》2006,86(2):553-559
Lanthanum-bearing silicate-oxyapatites or britholites, Ca10–xLax(PO4)6–x(SiO4)xO with 1≤x≤6, have been synthesized by solid state reaction
at high temperature. They were characterized by X-ray diffraction and IR spectroscopy.
Using two microcalorimeters, the heat of solution of these compounds have
been measured at 298 K in a solution of nitric and hydrofluoric acid. A strained
least squares method was applied to the experimental results to obtain the
solution enthalpies at infinite dilution, and the mixing enthalpy in two steps.
In the first step the mixing enthalpy obtained is referenced to the britholite
monosubstituted and to the oxysilicate. The mixing enthalpy referenced to
the oxyapatite and to the oxysilicate is then extrapolated. In order to determine
the enthalpies of formation of all the terms of the solution, thermochemical
cycles were proposed and complementary experiments were performed. The results
obtained show a decrease of the enthalpy of formation with the amount of Si
and La introduced in the lattice. This was explained by the difference in
the bond energies of (Ca–O, P–O) and (La–O, Si–O). 相似文献
3.
C. Marhag H. Said P. Satre C. Favotto J. Rogez 《Journal of Thermal Analysis and Calorimetry》2003,74(1):275-285
Study of solid-liquid phase diagram of LiPO3-Pb(PO3)2 binary system, in certain calcination conditions, shows the existence of several metastable phasis. When heated at a temperature
of 723 K the binary mixtures lead uncompletely to a defined compound Pb2Li(PO3). On heating these ternary solid mixtures, three eutectic reactions have been observed: LiPO3+Pb(PO3)2→Liquid at a temperature of 793 K(1) LiPO3+Pb2Li(PO3)5→Liquid at a temperature of 843 K (2) Pb2Li(PO3)5+Pb(PO3)2→Liquid at a temperature of 891 K (3) The metastable liquid phase appears in the system at temperature of 793 K. DTA experiments
performed on the binary LiPO3-Pb(PO3)2 mixtures, show a superposition of two diagrams. The first one is metastable and the second represents the stable equilibrium
phase diagram. Measurements of liquid enthalpy of binary LiPO3-Pb(PO3)2 system at temperature of 979.65 K were reported. The corresponding values were very small and so the binary system can be
considered as athermal. Assuming an ideal behaviour, the liquidus curves in the metastable diagram were calculated and the
eutectic reaction (LiPO3-Pb(PO3)2→Liquid) was confirmed at 793 K.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Aragon E. Jardet K. Satre P. Sebaoun A. 《Journal of Thermal Analysis and Calorimetry》1998,53(3):785-795
The first part of this paper presented five experimental isopletic cuts in the Al-Zn-Ga ternary phase diagram. On these cuts,
two isobaric ternary invariant reactions were determined and a significant retrograde miscibility of Ga in a α′SS solid solution was observed.
In the second part, the two isobaric invariant reactions are studied more precisely. In particular, the composition of the
invariant phases are given and the Ga miscibility in the αSS ternary solid solution is studied. Isothermal sections are established. The results confirm the existence of a vanishing
point in the liquidus area, conjugated with a ternary critical point at about 290°C. A general perspective shape of the equilibria
in the diagram is proposed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
Aragon E. Jardet K. Satre P. Sebaoun A. 《Journal of Thermal Analysis and Calorimetry》1998,53(3):769-784
The Al-Zn-Ga ternary phase diagram was earlier established by thermodynamic modellization [1], but no experimental study appears
to have been carried out on this system, except for measurements of mixing enthalpies in the liquid [2].
The present experimental study was carried out by thermal analysis and X-ray diffraction at various temperatures, using the
isopletic cuts method.
Four isopletic cuts were established and two others were partly studied in the Al-rich corner of the diagram. On these cuts,
two isobaric ternary invariant reactions were determined: a eutectic reaction at 23±1°C, and a metatectic reaction at 123±1°C.
Evidence was found for the existence of a retrograde miscibility of Ga in a solid solution α′SS which protrudes into the ternary system starting from the Al-Zn binary up to a Ga concentration of about 30%*.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Aragon E. Jardet K. Satre P. Sebaoun A. 《Journal of Thermal Analysis and Calorimetry》2000,62(1):211-225
The Al–Ga–Zn ternary phase diagram presents two isobaric invariant reactions: a eutectic at 23±1°C and a metatectic at 123±1°C
[1–3]. Calorimetric measurements on the two isobaric invariant reactions have been carried out. First the Tammann method has
enabled us to determine the composition of their limits on five isopletic cross sections. Then, the compositions of the invariant
phases have been determined.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
DTA-DTG systematic study of highT c superconducting phase (Bi,Pb)2Sr2CaCu2O8+x, with and without lead, shows a quantitatively opposite variation of oxygen stoechiometry on heating and cooling. Multiplate sample container, designed for the study, allowed to dissociated PbO loss from oxygen variations. Phases transformations have been studied under severalP O2 by scanning DTA and DTG. Oxygen variations evolution has been evaluated by isothermal TG. The results proved that phase diagram representation must take into consideration theP O2 coordinate. 相似文献
8.
M. Mansori C. Favotto K. Jardet M. Roubin A. Sebaoun P. Satre 《Journal of Thermal Analysis and Calorimetry》1997,50(3):401-407
The oxygen exchange between the condensed phase(s) and the gas phase was studied as a function of temperature for superconducting phases of the system (Bi,Pb)-Sr-Ca-Cu-O.An oxygen probe apparatus allowed confirmation that the variation in oxygen composition in the Pb2212 and Pb2223 superconducting phases is a reversible phenomenon on heating and cooling. It was demonstrated that the mass loss of both phases, for the 905 and 980°C isotherms, was due to the oxygen composition variation and to PbO loss (this latter phenomenon begin irreversible). 相似文献
9.
Simultaneous measurements of variations in magnetic and dilatometric properties were successfully used to detect the phase transition occurring during the thermal treatment of iron(III) oxide microcrystals. The increase of the compacting pressure, i.e. the increase of the interparticular number, favours the irreversibleγ→α transition. An unusual phase of iron(III) oxide, different from theγ-phase, has been unambiguously demonstrated. Its stability seems to be improved by the surface energy excess due to the highly-divided state. 相似文献
10.
The elaboration of Na+ super-ionic conductor (NaSICON) ceramics is studied in this work. These solid electrolytes can be used as sensor for detection
of polluted gases in air. Two sorts of ceramics with different chemical compositions are synthesised by soft chemistry route:
a zirconium-based NaSICON and a hafnium-based NaSICON. DTA-TG and temperature depending X-ray diffractometry were used to
follow the thermal decomposition of the precursor phases. The electrical properties of these ceramic sodium ionic conductors
are investigated by complex impedance spectroscopy (CIS). The substitution of the zirconium by the hafnium increases the ceramic
conductivity and decreases the activation energy E
a (from 0.29 to 0.12 eV).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献