Loss Of Te Research Articles

Ion channeling and Auger electron spectroscopy study of Sb-diffused Pb1−xSnxTe crystals

An experimental study has been made of the effect of Sb diffusion on the crystalline quality and surface composition of Pb1−xSnxTe single crystals (x≊0.13) used in fabricating homojunction diode lasers. Both ion backscattering-channeling and Auger electron spectroscopy have been employed. It is found that the crystalline quality in the bulk improves on diffusion, due to a decrease in dislocation density associated with the diffusion temperature. In the near-surface region the quality deteriorates, due to the production of defects which are probably small clusters associated with Sb. The most pronounced effect is a partial or total loss of Te (and probably Sn) from the native oxide, accompanied by other changes in the oxide composition. A long term growth of a very thick oxide also occurs following diffusion. The changes in the oxide can be related to the formation of a p-type surface layer on diffused crystals exposed to air, through oxygen adsorption.

The effect of radiation-chemical crosslinking of polyethylene on its capacity to form autohesion bonds during seam welding

TH~ erossl inking p roduced in po lymers b y ionizing rad ia t ion [1, 2] has a s t rong influence on the i r capac i ty to fo rm au tohes ion bonds dur ing seam welding. The comple te loss of weldabi l i ty of po lye thy lene (PE) films subjec ted to ~-radiat ion in air a t doses of 6-12 Mrad had been no ted [3]. The de te r io ra t ion of the au toand adhes ion capac i ty was also observed on sys t ems sub jec ted to vulcaniza t ion [4, 5]. The c rys ta l l in i ty of a p o l y m e r was also found to h inder the au tohes ion bond forming dur ing welding; this appea r s to be due to a lack of macroand v e r y res t r i c ted mic ro -Brownian m o v e m e n t of the molecules. Al though the influence of s t ruc tu re or c rys ta l l in i ty on the au tohes ion of po lymer s is of considerable impor tance , the quest ion has not been ful ly clarified. The s i tua t ion is made still more difficult b y the s t ruc tu ra l changes which occur dur ing welding itself, these being in addi t ion to the molecular crossl inking by i r rad ia t ion or vulcaniza t ion . The work r epo r t ed here deals wi th the effect of the e n u m e r a t e d fac tors on au tohes ion a n d the s t r eng th of the welding joint.

Crystal growth and orientation in sputtered films of bismuth telluride

Abstract Films in the thickness range from 300 A to 3 μ have been prepared by sputtering from a cathode of composition Bi2Te3 in an atmosphere of pure argon. At low substrate temperatures the stoichiometric Bi2Te3 composition is retained in the sputtered deposits, but with increasing temperature, above 250°c, progressive loss of Te occurs, until at 420°c the film composition corresponds approximately to BiTe. The Te-deficient film structures are identified as metastable β-type phases which are of the same structure type as Bi2Te3. On amorphous substrates fibre textures are developed which change from a {1015} to a {0001} type as the temperature is raised. The corresponding single-crystal orientations are obtained by epitaxy on the (100) and (111) planes respectively of NaCl crystals. The texture changes are accompanied by striking changes in the crystal habit. Hexagonal platelets appear at low temperatures and very high temperatures, while well-developed octahedra are observed at intermediate temperatures...

A simple calculation of dielectric loss from dielectric dispersion for polar polymers

For polar polymers undergoing orientation polarization it is possible to calcula te dielectric losses from dielectric constant data by use of a single approximation already familiar from its application to mechanical properties, if t his approximation is applied to t he real part of t he dielectric constant only and if data over a sufficiently wide frequency range are available. Data obtained at frequen cies from 102 to 108 cycles per second for Butvar and for a copolymer of styrene and methyl methacrylate are analyzed and it is fou nd that observed and calculated values of t he dielectric losses agree wi thin 10 percent or better .