Liquid Nitrogen Temperature Range Research Articles

High Tc Superconductivity in Metallic Oxide Compounds

Different preparation techniques were elaborated for obtaining La–Ba–Cu–O, La–Sr–Cu–O, Y–Ba–Cu–O, Y–Sr–Cu–O, Y–La–Ba–Cu–O and Y–La–Ba–Sr–Cu–O metallic oxide superconductors. Physical and chemical properties of them were analysed by thermogravimetry, powder X-ray, SEM, electron microprobe and SIMS which hint at a multiple-phase structure of the compounds in question. Tc for one part of samples is higher than 50 K and for the other part falls into liquid nitrogen temperature range above 90 K. Superconductivity was confirmed by magnetic measurements too. A change in Fermi-surface topology due to the increasing additive material content and a supplementary percolation process can be treated as the main effects for high-Tc superconductivity.

Extrinsic silicon detectors for 3–5 and 8–14 μm

In support of system applications which operate in the 3–5 and 8–14 μm spectral ranges, high performance doped silicon detectors are desired to allow for the integration of detectors and silicon electronics on the same substrate. For the 8–14 μm range, detectors were prepared using aluminum, gallium, bismuth and magnesium as dopants which operate in the liquid neon temperature (27°K) range. For the 3–5μm range, detectors were prepared using indium, sulphur and thallium as dopants which operate in the liquid nitrogen temperature (78° K) range. The spectral and temperature characteristics of these detectors are presented. Background limited performance (∼30° FOV) is demonstrated for Si:Al. Si:Ga. and Si:Bi up to temperatures of about 30°K. Background limited performance (∼30° FOV) is demonstrated for Si:In and Si:S up to temperatures of approximately 60 and 75°K respectively. The data gives a good fit with theory based on background and temperature limitations. The performance of the Si:Mg detector is limited by a shallow unidentified energy level while that of the Si:TI detector is limited, at present, by low responsivity.

ChemInform Abstract: A TETRAMERIC COBALT(II) CLUSTER OF 7-AZAINDOLE

Der durch Zugabe einer methanolischen KOH-Lösung zu einem Gemisch von Co(II)- acetat und 7-Azaindol in Methanol gebildeten, antiferromagnetischen Verbindung wird anhand von elektronen-, IR- und massenspektroskopischen sowie magnetischen Untersuchungen eine tetramere Cluster-Struktur zuerkannt.

A magnetic study of a series of dihydroxy-bridged copper compounds of 2,2'-bipyridyl and 1,10-phenanthroline

The magnetic susceptibility of the compounds [(amine)Cu(OH)]2X2,nH2O, where amine = 2,2'-bipyridyl or 1,l0-phenanthroline; X = Cl, I, NCS, NCSe, or �SO4; and n varies from 5 to 1 depending on the complex, has been measured in the liquid nitrogen temperature range. The magnetic data are consistent with a triplet ground state for the sulphate and iodide salts.

The magnetic susceptibility of CsTi(SO4)2∙12H2O

The magnetic susceptibility of CsTi(SO4)2∙12H2O (CsTi alum) was measured with a Foner magnetometer in the temperature range 4.2 to 300 °K. Emphasis was placed on the liquid-helium to liquid-nitrogen temperature range, since complete measurements for this temperature region have not been reported previously.The experimental results were interpreted with an expression derived by Kamimura for the effective moment of Ti3+ ions as a function of temperature in a crystalline electric field of trigonal or tetragonal symmetry. A best fit to the experimental data was obtained with values of [Formula: see text] and λ = 25.2 ± 5.0 cm−1. These values indicate the presence of an excited energy state approximately 30 cm−1 above the ground state; in addition there is a substantial reduction in the spin–orbit coupling factor from the free-ion value.

Shubnikov-De Haas effect in the temperature range between T = 2°K and T = 77.4°K

SdH oscillations are shown to occur up to the liquid Nitrogen temperature range. This behaviour, observed in highly doped Bi 95Sb 5 ( n = 1.45 × 10 19 cm −3), is explained by the theory of ionized impurity scattering. Heavy mass electrons, located in a subsidiary conduction band minimum, give rise to a screening effect, drastically reducing the impurity scattering of the light electrons.

Injection and Field‐Induced Excitation of charge Carriers in CdS single Crystals

AbstractThe current‐voltage characteristics of CdS single crystals were investigated in the temperature range of liquid nitrogen up to fields of the order 105 V/cm. At low electrode separations double injection predominates. At larger distances, however, impact ionization of a shallow trapping state, positioned in the range of 0.1 to 0.2 eV below the conduction band is found. An investigation of the characteristics at different electrode separations and temperatures as well as different directions of the electric field intensity with respect to the c‐axis supports the statements.