National Institute Of Materials Physics - Romania

Publications

894 articles found

861. A NOTE ON OFF-CENTER DIFFUSION

Authors: DESPA, F; APOSTOL, M

Published: APR 1995, SOLID STATE COMMUNICATIONS, 94, 155, DOI: 10.1016/0038-1098(94)00855-8

Within a one-dimensional model of off-centre diffusion it is shown that the diffusion coefficient depends on the number of off-centre sites and on their orientation relative to the host lattice.

862. IR SPECTROSCOPIC MEASUREMENTS OF CRYSTALLINITY AND PHASE PURITY OF ZSM-5 SAMPLES

Authors: FRUNZA, L; DINCA, V; VAGAON, M; CRISAN, D; FLORESCU, I; MANOIU, D; CRISAN, M; RAGAN, N

Published: MAR 1993, REVUE ROUMAINE DE CHIMIE, 38, 246, DOI:

The use of IR spectroscopic method to choose the best batches of ZSM-5 zeolites. is discussed. The crystallinity and the particle size were estimated from IR spectra and by XRD and electron microscopy measurements.

863. HOPPING CONDUCTIVITY OF THE FIBONACCI-CHAIN QUASI-CRYSTAL - COMMENT

Authors: DULEA, M; ALDEA, A

Published: OCT 1 1992, PHYSICAL REVIEW B, 46, 8643, DOI: 10.1103/PhysRevB.46.8642

This Comment refers to a recent publication on the ac hopping conduction of the Fibonacci chain [Phys. Rev. B 43, 1183 (1991)]. The renormalization procedure proposed by its authors gives a correct formula for the conductivity [Eq. (15)]. Nevertheless, their conclusion regarding the vanishing of the dc conductivity disagrees with the low-frequency asymptotics previously derived by us for the same model, and also disagrees with the general result given by the resistance-network analogy of the Miller-Abrahams rate equations. Their result assumes the factorization of the frequency in Eq. (15), which we prove is not true. We show also that their numerical curves, which apparently support their conclusion, are strongly influenced by errors in the low-frequency range.

864. 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.

865. IR STUDY OF METAL-SUPPORT INTERACTIONS IN NI AL2O3 CATALYSTS FOR CO HYDROGENATION

Authors: FRUNZA, L; UDREA, M; UDREA, I; CAPAT, C; CRISAN, D; NICOLESCU, IV

Published: FEB 1990, REVUE ROUMAINE DE CHIMIE, 35, 227, DOI:

866. THE THERMOPOWER OF NON-LOCALIZED ELECTRONS IN AMORPHOUS-SEMICONDUCTORS

Authors: ALDEA, A

Published: DEC 1989, JOURNAL OF NON-CRYSTALLINE SOLIDS, 114, 377, DOI: 10.1016/0022-3093(89)90168-3

867. THE EFFECT OF THE TEMPERATURE SHIFT OF THE ENERGY-BANDS ON THE THERMOPOWER OF QUASI-FREE ELECTRONS IN SEMICONDUCTORS

Authors: ALDEA, A

Published: SEP 1989, PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL MECHANICS ELECTRONIC OPTICAL AND MAGNETIC PROPERTIES, 60, 398, DOI: 10.1080/13642818908205915

868. LONG-TIME ASYMPTOTICS IN THE ONE-DIMENSIONAL TRAPPING PROBLEM WITH LARGE BIAS

Authors: ALDEA, A; DULEA, M; GARTNER, P

Published: AUG 1988, JOURNAL OF STATISTICAL PHYSICS, 52, 1068, DOI: 10.1007/BF01019739

869. HOPPING CONDUCTION ON APERIODIC CHAINS

Authors: ALDEA, A; DULEA, M

Published: APR 18 1988, PHYSICAL REVIEW LETTERS, 60, 1675, DOI: 10.1103/PhysRevLett.60.1672

870. PHOTOLUMINESCENCE OF THE HOPPING DISORDERED-SYSTEMS WITH ELECTRICAL BIAS

Authors: DULEA, M; ALDEA, A

Published: FEB 1987, JOURNAL OF NON-CRYSTALLINE SOLIDS, 90, 464, DOI: 10.1016/S0022-3093(87)80464-7