L. Ben-Dor
Hebrew University of Jerusalem
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Featured researches published by L. Ben-Dor.
Materials Research Bulletin | 1981
G. Dishon; M. Schieber; L. Ben-Dor; L. Halitz
The occurrence of deviations from stoichiometry of the semi-insulator compound HgI2 has been established using a very elaborate chemical analytical procedure. It was found that the molar ratio of I2Hg varies from 1.993 to 2.015 (±0.002). The deviations from stoichiometry have been corroborated by studying the red to yellow solid state phase transformation temperature. It was found that the compounds, whether rich or poor in iodine, have lower Ttr than those closest to stoichiometry, i.e., where the I2Hg ratio is 2.000.
Materials Research Bulletin | 1974
L. Ben-Dor; Y. Shimony
Abstract Single crystals of MoO 2 and WO 2 , pure and doped with NiO, were grown by chemical transport in Vycor ampoules using iodine as the transporting agent. From X-ray diffraction analyses it was found that all the crystals were monoclinic, and that doping up to 5% does not change the unit cell constants. The pure dioxide crystals are weakly paramagnetic χ M −6 emu, but doping raises the magnetic susceptibility markedly: ∼ 2500×10 −6 emu. Resistance studies show that these materials are metallic conductors, the room temperature specific resistivity being of the order of 10 −4 – 10 −3 Ωcm, decreasing by one order of magnitude at liquid nitrogen temperature. Doping also substantially lowers the conductivity.
Journal of Crystal Growth | 1983
A. Horowitz; D. Gazit; J. Makovsky; L. Ben-Dor
The Accelerated Crucible Rotation Technique (ACRT) was applied to the Bridgman growth of (incongruently melting) Rb2MnCl4 from non-stroichiometric melts. ACRT mixing allowed us to increase the crystal growth rates by at least a factor of four compared to the maximum growth rate, in order to obtain inclusion-free crystals, without stirring. The existing analytical data do not allow a prediction of the optimum ACRT parameters and it is possible that even higher growth rates could still be achieved. The ACRT-induced changes of the fluid flow velocity past the growing face and of the thickness of the diffusion boundary layer were calculated.
Thermochimica Acta | 1975
L. Ben-Dor; Dror Perez
Abstract A thermal analysis study of the effect of CaCl 2 , CdI 2 and CrCl3 on the hydration reaction of 3CaO·SiO 2 (C 3 S) was performed. The model suggested is derived from both the thermoanalytical studies and the infrared spectra.
Journal of Materials Science | 1976
L. Ben-Dor; Dror Perez
The influence of various inorganic salts, used as additives to Portland cement paste, on strength development was studied. The salts used were: CaCl2, CrCl3, Cdl2. It was found that CaCl2 and CrCl3 accelerate the rate of strength development, while Cdl2 retards it compared to Portland cement without admixtures. No influence by CdCl2 was observed. The effect of the same admixtures on the microstructure of hydrated tricalcium silicate was examined by a scanning electron microscope, and correlation between the morphology of the simple system and the mechanical behaviour of the complex cement system is discussed.
Physica C-superconductivity and Its Applications | 1992
L. Ben-Dor; M.Y. Szerer; G. Blumberg; A. Givan; Lars Börjesson; L.V. Hong
Abstract Samples of bismuth cuprate with and without lead substitution were prepared by the sol-gel method. The general formula was Bi 2− x Pb x Sr 2 CaCu 2 O 8+δ , where 0≤ x ≤0.6. The samples were characterized by X-ray diffraction (XRD), electron probe microanalysis (EPMA), magnetic susceptibility, Raman spectroscopy and IR reflectance. Regarding homogeneity, density, purity and superconductivity, optimal behavior was found x = 0.2-0.4. An increase of hole concentration in the CuO 2 -planes with Pb 2+ /Bi 3+ ratio was observed from the optical data. The Raman spectra modifications with lead substitution are discussed. Evidence of the interaction between CuO 2 -plane hole continuum and 150 cm −1 IR active modes was found.
Journal of Solid State Chemistry | 1990
L. Ben-Dor; Hussam Diab; I. Felner
Abstract The high-temperature superconducting phase of the Bi-2223 system, with and without Pb, was prepared by the sol-gel method. The material was characterized by X-ray powder diffraction and by magnetization. An almost pure phase was obtained on the addition of Pb(NO 3 ) 2 (0.2 m ) in substitution for the Bi and less time for sintering was needed.
Journal of Solid State Chemistry | 1980
L. Ben-Dor; I. Shilo
Abstract CdRE2S4 (RE = Gd, Tb, Dy, Ho, Er, Tm, and Yb) and Mg(GdxYb1−x)2S4 were prepared by solid-state reactions. All the cadmium-containing compounds are cubic, i.e., the Th3P4 structure for Gd, Tb, and Dy and the spinel type for all the others. The first three compounds were deficient in CdS. In the case of the Mg system, for x = 1 the system is cubic Th3P4, for x = 0 cubic spinel, and for 0
Journal of Crystal Growth | 1974
L. Ben-Dor; Y. Shimony
Abstract Thin films of CrO 2 on single crystal plates of Al 2 O 3 were grown by a vapor deposition process in sealed silica tubes. CrO 2 Cl 2 was formed from CrCl 3 . 6H 2 O and CrO 3 in one zone at 250 °C and decomposed to yield CrO 2 in a second zone at 380 °C. The overall pressure was less than 3 atm. The films were characterized by optical and electron microscopy, by X-ray analysis, by magnetic behavior and optical absorption.
Journal of Crystal Growth | 1985
L. Ben-Dor; N. Yellin
Abstract Single crystals of Cd 0.95 Zn 0.05 Te were grown by the vertical unseeded vapor growth. Large (1–2 cm 3 , homogeneous crystals with high purity and perfection were obtained. The system shows similarity to CdTe in its dependence of growth rate on time and on nonstoichiometry of the growth charges. The crystal resistivity was found to be strongly dependent on charge composition, being different from that observed for CdTe. Maximum resistivity of ∼ 10 7 Ω cm and a value of ∼ 10 2 Ω cm for Te-saturated Cd 0.95 Zn 0.05 Te were obtained.