National Institute Of Materials Physics - Romania

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5840 articles found

5361. MOSSBAUER AND MAGNETIC STUDIES OF AMORPHOUS (FE1-XYX)84B16 ALLOYS

Authors: ZHANG, PQ; ZHAO, JG; LI, S; GABURICI, D; NISTER, CI; FILOTI, G

Published: 1991, HYPERFINE INTERACTIONS, 69, 708, DOI:

Amorphous ribbons of (Fe1-xYx)84B16 with 0 < x < 0.21 were studied using Mossbauer and magnetic measurements. The results proved a short-range order interaction in the prepared samples and nonhomogeneous regions induced by yttrium presence.

5362. CRYSTALLINE PHASES IN SUPERCONDUCTING BI-SR-CA-CU2-O-X CERAMIC

Authors: POPESCU, M; ALDICA, G; SARBU, C; PAUSESCU, P; CRUCEANU, E; VASILIU, F; APOSTOL, M

Published: DEC 16 1990, PHYSICA STATUS SOLIDI A-APPLIED RESEARCH, 122, 643, DOI: 10.1002/pssa.2211220225

The crystalline phases in the superconducting ceramic Bi:Sr:Ca:Cu2:O(x) exhibiting either low superconducting transition (almost-equal-to 80 K) or both, low and high superconducting transitions (almost-equal-to 110 K) are identified by X-ray and electron diffraction. Two types of modulated structures are observed and their relation to T(c) is discussed within the frame of the oxygen-displacive mode theory.

5363. ON THE RELATIONSHIP BETWEEN THE STATIC RESPONSE AND CORRELATION-FUNCTIONS OF THE SPIN MAGNETIC-MOMENTS

Authors: MANOLESCU, A; MEZINCESCU, GA

Published: DEC 1 1990, PHYSICA A, 169, 429, DOI: 10.1016/0378-4371(90)90112-6

We consider homogeneous states of quantum multicomponent plasmas described by a spin-independent Hamiltonian. Using generalized-moment inequalities we show that the relation between the response and the correlation functions of the spin magnetic moments approaches the classical one in the infinite-wavelength limit (k-->0). For small k, the first correction is of order k2 and is bounded by the semiclassical correction.

5364. ON THE LIMITING FACTORS OF THE CRITICAL CURRENT-DENSITY IN HIGH-TC SUPERCONDUCTING CERAMICS

Authors: MIU, L; CRISAN, A; POPA, S; SANDU, V; NISTOR, L

Published: DEC 1990, JOURNAL OF SUPERCONDUCTIVITY, 3, 394, DOI: 10.1007/BF00617464

The temperature dependence of the critical current density at high temperatures and in weak applied magnetic field for YBa2Cu3O7-y ceramic samples with a pronounced granular character is analyzed. The experimental results can be explained in terms of thermally activated motion of the intergrain Josephson vortices at grain boundaries, which may be an indication that the actual limiting factor for the critical current density in ceramic samples results from a weak pinning force density for the intergrain vortices rather than from the weak-link quenching.

5365. HOPPING CONDUCTIVITY OF THE EXTENDED-HARD-CORE CUBIC LATTICE GAS

Authors: PITIS, R

Published: NOV 1 1990, PHYSICAL REVIEW B, 42, 8381, DOI: 10.1103/PhysRevB.42.8375

5366. MAGNETIC-PROPERTIES AND STRUCTURE OF RARE-EARTH TRANSITION-METAL THIN-FILMS IMPLANTED WITH AR+ IONS

Authors: FLORESCU, V; SERBANESCU, MD; MANAILA, R; GRANT, WA

Published: NOV 1990, JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 92, 142, DOI: 10.1016/0304-8853(90)90690-R

5367. DISTRIBUTION FUNCTION OF PRECIPITATED TIO2 PARTICLE VOLUMES

Authors: MANOLESCU, A; MANAILA, R; MEZINCESCU, GA; NISTOR, L; TEODORESCU, V; SERBAN, S; IOVITA, V

Published: OCT 1990, REVISTA DE CHIMIE, 41, 815, DOI:

The distribution function of precipitated particles in relation to their volume is modelled by a function reproducing the three moments of the real function. The time evolution of the distribution is simulated by the numerical solving of a non-linear differential equation system for the moments, resulting from the rate equation which describes the growth of the particles.

5368. UTILIZATION OF NMR-SPECTROSCOPY FOR THE DETERMINATION OF POLYACRYLAMIDE SOLUTIONS CONCENTRATION

Authors: CONTINEANU, M; CONSTANTINESCU, O

Published: SEP 1990, REVISTA DE CHIMIE, 41, 730, DOI:

A method of the determination of the concentration of the Medasol type hydrolized and non-hydrolized polyacrylamide in aqueous solution by higy resolution MNR is presented. The method may be applied to dilute solutions under the conditions presented in this paper.

5369. ON THE BOND ORIENTATIONAL ORDER IN ICOSAHEDRAL PHASES

Authors: RADULESCU, O; MANAILA, R

Published: SEP 1990, PHYSICA STATUS SOLIDI B-BASIC RESEARCH, 161, 73, DOI: 10.1002/pssb.2221610105

5370. INFLUENCE OF PHOSPHORIC-ACID AND OF PERCHLORIC-ACID ON ELECTROFORMATION OF ELECTRODES OF LEAD-SULFURIC ACID BATTERIES

Authors: MATEESCU, AG; MATEESCU, D

Published: SEP 1990, REVISTA DE CHIMIE, 41, 723, DOI:

The microstructure modifications have been studied during the electroformation of positive and negative plates which give information regarding the optimal conditions for the obtaining of plates for lead batteries. The microstructure proved to depend on the conditions under which the electroformation takes place and on the nature of the electrolyte additions. The SEM studies showed that in the positive active mass, the particles are heterogeneously scattered and that they consist of amorphous and crystalline areas.