References of "Houssa, M"
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See detailAging process of electrical contacts in granular matter
Dorbolo, Stéphane ULg; Ausloos, Marcel ULg; Vandewalle, Nicolas ULg et al

in Journal of Applied Physics (2003), 94(12), 7835-7838

The electrical resistance decay of a metallic granular packing has been measured as a function of time. This measurement gives information about the size of the conducting cluster formed by the well ... [more ▼]

The electrical resistance decay of a metallic granular packing has been measured as a function of time. This measurement gives information about the size of the conducting cluster formed by the well connected grains. Several regimes have been encountered. Chronologically, the first one concerns the growth of the conducting cluster and is identified to belong to diffusion processes through a stretched exponential behavior. The relaxation time is found to be simply related to the initial injected power. This regime is followed by a reorganization process due to thermal dilatation. For the long-term behavior of the decay, an aging process occurs and enhances the electrical contacts between grains through microsoldering. (C) 2003 American Institute of Physics. [less ▲]

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See detailNon-Gaussian behavior and anticorrelations in ultrathin gate oxides after soft breakdown
Vandewalle, Nicolas ULg; Ausloos, Marcel ULg; Houssa, M. et al

in Applied Physics Letters (1999), 74(11), 1579-1581

The time dependence of the gate voltage V-G(t) after soft breakdown of metal-oxide-semiconductor capacitors with a 2.4 nm SiO2 layer has been measured. It is found that the V-G(t) fluctuation ... [more ▼]

The time dependence of the gate voltage V-G(t) after soft breakdown of metal-oxide-semiconductor capacitors with a 2.4 nm SiO2 layer has been measured. It is found that the V-G(t) fluctuation distributions are non-Gaussian, but can be described by a Levy stable distribution. The long-range correlations in V-G(t) are investigated within the detrended fluctuations analysis. The Hurst exponent is found to be H = 0.25 +/- 0.04 independent of the value of the stress current density J. It is argued that these are universal features of soft breakdown and are due to trapping-detrapping of electrons in and away from the primary percolation path. [less ▲]

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See detailComment on "Observation of vortex-lattice melting in YBa2Cu3O7-delta by Seebeck-effect measurements"
Ausloos, Marcel ULg; Bougrine, Hassan ULg; Houssa, M. et al

in Physical Review. B : Condensed Matter (1999), 59(1), 671-673

The findings of Ghamlouch et al. [Phys. Rev. B 54, 9070 (1996)] on the jump in the thermoelectric power of high-T-c superconductors below the critical temperature in the presence of large magnetic fields ... [more ▼]

The findings of Ghamlouch et al. [Phys. Rev. B 54, 9070 (1996)] on the jump in the thermoelectric power of high-T-c superconductors below the critical temperature in the presence of large magnetic fields are discussed. The complicated interplay between the vortex lattice thermodynamic transitions and the transport property percolation transitions raises questions on their similarities, differences, and relationships with respect to the (B,T) phase diagram features and the classical Kosterlitz-Thouless transition. A few comments pertain to the experimental details and others on the relevant role of thermomagnetic transport properties. [S0163-1829(99)04102-8]. [less ▲]

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See detailTransport properties of HgBaCaCuO(1223) polycrystalline superconductors
Bougrine, Hassan ULg; Houssa, M.; Cloots, Rudi ULg et al

in Superconductor Science & Technology (1998), 11(1), 128-132

We report on the temperature (20-300 K) dependence of the resistivity, thermopower and thermal conductivity measurements of HgBaCaCuO(1223) polycrystalline superconductors with nominal composition Hg1 ... [more ▼]

We report on the temperature (20-300 K) dependence of the resistivity, thermopower and thermal conductivity measurements of HgBaCaCuO(1223) polycrystalline superconductors with nominal composition Hg1.4Ba2Ca2CU3O8+delta. We present some discussion of the precision and the originality of the measurement methods which are especially used to measure the electrical resistivity and simultaneously the thermopower and the thermal conductivity as a function of temperature. The superconductivity fluctuation contributions to the transport properties of the materials are calculated and compared. The results are related to the 2D anisotropy of the crystallographic structure. [less ▲]

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See detailSuperconductivity fluctuation effects on the thermal conductivity of Bi2Sr2CaCu2O8
Houssa, M.; Bougrine, Hassan ULg; Stassen, S. et al

in Physical Review. B : Condensed Matter (1996), 54(10), 6885-6888

The superconductivity fluctuation contribution kappa(B) to the thermal conductivity of a Bi2Sr1.8Ca1.2Cu2O8+y polycrystal is extracted from precise experimental data. The crossover from two-dimensional ... [more ▼]

The superconductivity fluctuation contribution kappa(B) to the thermal conductivity of a Bi2Sr1.8Ca1.2Cu2O8+y polycrystal is extracted from precise experimental data. The crossover from two-dimensional (2D) to 3D behavior theoretically predicted by Varlamov and Livanov is well marked. The crossover temperature T-VL and the amplitude of the fluctuation contribution lead to realistic values for the interlayer coupling energy J(C) and the transport relaxation time tau near T-c. [less ▲]

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See detailTHERMAL-CONDUCTIVITY OF PURE OR IRON-DOPED YBA2CU3O7-DELTA WITH OR WITHOUT AN EXCESS OF CUO
Houssa, M.; Bougrine, Hassan ULg; Ausloos, Marcel ULg et al

in Journal of Physics : Condensed Matter (1994), 6(31), 6305-6316

The thermal conductivities of YBa2(Cu1-xFex)3O7-delta + y% CuO ceramics for 0 < x < 0.03 and 0 < y < 5 have been measured. The thermal conductivities of all samples exhibit a minimum in the vicinity of ... [more ▼]

The thermal conductivities of YBa2(Cu1-xFex)3O7-delta + y% CuO ceramics for 0 < x < 0.03 and 0 < y < 5 have been measured. The thermal conductivities of all samples exhibit a minimum in the vicinity of the critical temperature T(c) and a maximum near T(c)/2. These results are interpreted with the help of an electronic model, i.e. supposing that the main contribution to the thermal conductivity below T(c) is due to electron scattering in the CuO2 planes. Within a simple two-fluid model derived from kinetic theory, taking into account the temperature dependence of the electronic relaxation time and the normal charge carrier concentration, we obtain theoretical curves which reproduce the experimental results quite well. We also take into account the porosity of the samples (in term of an intergrain contribution) to derive the electronic thermal conductivity. The parameter values of the model and the observed minimum are explained in terms of physical properties. In particular, the contribution of superconductivity fluctuations to the thermal conductivity is shown to be negligible with respect to other mechanisms. [less ▲]

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See detailBI-BASED 2223 SUPERCONDUCTING POLYCRYSTALLINE MATERIALS PREPARED BY EITHER A SOLID-STATE ROUTE OR A GLASSY MATRIX PRECURSOR METHOD - CHEMICAL-ANALYSIS AS WELL AS ELECTRICAL AND THERMAL TRANSPORT-PROPERTIES
Cloots, Rudi ULg; Bougrine, Hassan ULg; HOUSSA, M. et al

in Physica C (1994), 231(3-4), 259-270

Two routes have been followed in order to prepare Bi1.7Pb0.3Sr2Ca2Cu3O(y) superconducting materials. Bi1.7Pb0.3CuO4 is always used as one of the starting basic materials. The first route involves a new ... [more ▼]

Two routes have been followed in order to prepare Bi1.7Pb0.3Sr2Ca2Cu3O(y) superconducting materials. Bi1.7Pb0.3CuO4 is always used as one of the starting basic materials. The first route involves a new experimental procedure based on the solid state synthesis of separate intermediate phases, mixed together in a two (Bi1.7Pb0.3CuO4 + 2SrCaCuO3), three (Bi1.7Pb0.3CuO4+2SrCuO2+2CaCO3) or four (Bi1.7Pb0.3CuO4+(1/12)Sr8Ca6Cu24O41 + (3/2)CaCO3 + (4/3)SrCO3) powder process. Electric resistivity versus temperature measurements are presented. Even though the T(c)(0) of each sample is above 100 K, X-ray diffraction shows that the main phase is the 2212 phase in each case. Relatively pure 2223 materials have, however, successfully been produced by the second method, which starts from a glassy intermediate phase and involves a so-called 'matrix' method. The glass precursor phase is composed of one (Bi1.7Pb0.3CuO4), two (Bi1.7Pb0.3CuO4 + 2CaCO3), and three (Bi1.7Pb0.3CuO4 + (3/2)CaCO3 + (4/3)SrCO3) components as for the solid state routes. The role of both the added alkaline earth crystalline compounds and the glass matrix precursors in this second method turns out to be very important. We propose a schematic structural model in order to explain the selectivity of the starting materials. SrCaCuO3 is found to be a good precursor of the 2212 phase, while SrCuO2 gives rise to the 2223 phase. It seems that the presence of CaCO3 in the glassy intermediate phase, thus acting as a cation reservoir, is very useful for the production of the 2223 phase. Electric resistivity, thermal conductivity and thermopower versus temperature measurements are also presented and discussed in terms of intergrowths and variations of cationic compositions in the Bi-based layers. [less ▲]

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See detailTHERMOELECTRIC-POWER AND THERMAL-CONDUCTIVITY IN YBA2(CU1-XFEX)(3)O-7-DELTA WITH OR WITHOUT EXCESS OF COPPER-OXIDE
Bougrine, Hassan ULg; Ausloos, Marcel ULg; HOUSSA, M. et al

in Physica C (1994), 235(Part 2), 1465-1466

Thermoelectric power and thermal conductivity of YBa2(Cu1-xFex)(3)O-7-delta polycrystals for 0<x<0.03 and with y% CuO (y equals 0 and 5) extrinsic impurity were simultaneously measured as a function of ... [more ▼]

Thermoelectric power and thermal conductivity of YBa2(Cu1-xFex)(3)O-7-delta polycrystals for 0<x<0.03 and with y% CuO (y equals 0 and 5) extrinsic impurity were simultaneously measured as a function of temperature. Samples were prepared following the same synthesis runs, and characterized by X-ray, EDX, and magnetic susceptibility techniques. When increasing copper oxide concentration, the transition is unaffected with respect to the pure sample, and the thermal transport coefficients correspond to very well oxygenated systems. Fe doped samples showed a lower transition temperature and features corresponding to low oxygenation systems. Fe doped sample with CuO revealed also the partial absorption of Fe by the ''extra CuO phase'' due to the 'dilution' of iron in the excess of CuO al grain boundaries. Fe-doping and excess CuO markedly reduce the thermal conductivity. [less ▲]

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