摘要:

Numerous materials have been deposited as amorphous films but our understanding of this phase is lacking. Since opinions regarding short-range order diverge, the similarities and differences between the liquid and amorphous phases are discussed first. It is then concluded from experimental data that the atomic arrangement in “ordered agglomerates with spherical close packing” differs from that in small crystallites. A review of experimental results for alloys, for elements with homopolar binding, and for semimetals and metals indicates that the metastable disorder in these groups of materials displays different characteristics. Interpretations for the varying degree of thermal stability, for size-dependent transitions, and for the kinetics of the transformation are given. Based on these considerations, a concept for the formation and crystallization of amorphous films is developed which shows the progressive change of the characteristics among the groups of materials.

ISSN:0022-5355    

DOI:10.1116/1.1492879

出版商:American Vacuum Society    

年代:1970

数据来源: AIP

摘要:

Deposits of 304L stainless steel from 0.002–0.064 in. thick were produced at rates from 0.002–0.00075 in./h by triode sputtering techniques. Substrates were maintained at temperatures from 1 °–800 °C. The 304L, alloy was found to be removed by krypton atoms at a rate of 4.6 g/A-h (22 atoms/ion) with the target at 1509 V. The 0.064-in-thick sample produced on a substrate held at 1 °C showed a variation in columnar grain microstructure through the deposit thickness. Chemical analysis showed that the alloy composition of the deposits was nearly the same as the target. The data indicated that the deposits had slightly more chromium, but less nitrogen and carbon than the target. Electron microprobe data indicated the deposits were uniform in chromium and nickel concentrations. The deposit appearance, microstructure, and crystal structure were strongly dependent on substrate temperature. The deposits had dull surfaces, columnar grain microstructures, and body-centered cubic (bcc) crystal structure for substrate temperatures below about 360 °C. Between 360 ° and 500 °C the surfaces had mirror finishes, the grains were equiaxed, and the deposits consisted of a mixture of face-centered cubic (fcc) and bcc phases; at 500 °C the deposit was essentially all fcc. At 800 °C the deposit had a mirror finish, the grains were columnar, and the crystal structure was fcc.

ISSN:0022-5355    

DOI:10.1116/1.1492880

出版商:American Vacuum Society    

年代:1970

数据来源: AIP

摘要:

A new method of measuring sticking coefficients using multiple surface collisions of vapor is presented. Metal vapors pass from a cup into a long, hollow, right cylindrical tube where they come to rest after one or more strikes on the inner surface of the tube. Analysis of the data are made by Monte Carlo statistical calculations of the behavior of atoms in a similar (though hypothetical) tube and using various assumptions regarding sticking coefficients and types of reflections. The sticking coefficient for silver on Pyrex in a residual vacuum of approximately10−5Torr and 20 °C is0.68±0.02. Reflections from Pyrex surfaces are shown, within experimental uncertainty, to be satisfactorily diffuse.

ISSN:0022-5355    

DOI:10.1116/1.1492882

出版商:American Vacuum Society    

年代:1970

数据来源: AIP

摘要:

A cylindrical magnetic spectrometer for the study of the electron impact desorption of ions and neutrals from solid surfaces is described. The instrument has an energy resolution of approximately 4% and sufficient sensitivity to allow the measurement of the ion energy distributions for systems in which the ion yield is10−9ions per electron or greater. In addition, the apparatus allows the determination of the mass-to-charge ratio of the emitted ions. The design of the apparatus and experimental procedures are discussed. Examples of typical measurements are reported.

ISSN:0022-5355    

DOI:10.1116/1.1492884

出版商:American Vacuum Society    

年代:1970

数据来源: AIP

摘要:

A cylindrical magnetic spectrometer has been constructed to study electron impact desorption of ions and neutrals from solid surfaces. The apparatus has been applied to the study of polycrystalline tungsten withO2, CO,CO2,N2,H2, andH2Oadsorbed. This paper reports the results of the measurements of the kinetics of the adsorption and desorption processes, the states of adsorption which are observed, the total desorption cross sections for these states, and electronic and thermal conversion between states.

ISSN:0022-5355    

DOI:10.1116/1.1492886

出版商:American Vacuum Society    

年代:1970

数据来源: AIP

摘要:

Physisorption isotherms have been measured for nitrogen on 304 stainless steel in the temperature range 77–90 K and in the pressure range10−9−10−4Torr. A static technique was used to obtain the isotherms whereby the pressure change of nitrogen in a constant volume system was measured on immersion of the test surface in different cryogenic baths. The Dubinin-Radushkevich equation provided a good correlation of the data and the extrapolated value for monolayer coverage of6.6×1014molecules/cm2indicated a roughness factor near unity for stainless steel. The isosteric heat of adsorption of nitrogen on stainless steel remained constant at about 4.4 kcal/mole in the range of surface coverages from 0.02–0.08.

ISSN:0022-5355    

DOI:10.1116/1.1492888

出版商:American Vacuum Society    

年代:1970

数据来源: AIP

摘要:

A series of temperature and pressure measurements are described which were made on a low pressure system in which water vapor leaves ice samples and passes through air to a vacuum pump in a cylindrical geometry. Evidence of a Gaede-type pumping of the air is noted. Saturation vapor pressures associated with the steady-state ice temperatures are found to have a linear relationship with the air pressures maintained by the pump, allowing the use of ice as a pressure “gauge.” A heat flow balance equation is used to confirm the applicability of diffusion theory to the water vapor flow (at a sufficient distance from the ice), and arguments based on this equation are used to explain the linearity described above. A kinetic theory treatment by Takaishi is compared with the present measurements, and the possibility of a more complete description of the system is discussed.

ISSN:0022-5355    

DOI:10.1116/1.1492890

出版商:American Vacuum Society    

年代:1970

数据来源: AIP

摘要:

A frequently observed characteristic of quadrupole mass filters is the appearance, at high resolution, of a separate “precursor” peak on the low mass side of each mass peak. The present report shows that such false precursor peaks can result from the use of round rods (rather than hyperbolic rods) that are common in all commercial instruments. Round rods introdnce sixth- and tenth-order terms to the ideal quadrupole field. We have computed the amount of sixth-order distortion introduced by the use of circular rods. The equipotential line produced at the surface of a round rod can be represented quite well by a quadrupole field with a large amount of sixth-order distortion. This distortion introduces a resonance line in the Mathieu stability diagram that at high resolution is near the edge of the peak on the low mass side. The resonance line can distort the peak to produce an apparent precursor peak.

ISSN:0022-5355    

DOI:10.1116/1.1492892

出版商:American Vacuum Society    

年代:1970

数据来源: AIP

摘要:

Single crystals of ferroelectricBi4Ti3O12are known to possess novel optical properties with potential use in optical memory or display applications. There is interest in duplicating these properties in thin films. Suitability of reactive and rf sputtering for preparation of stoichiometric films has been investigated. Films from stoichiometric targets were Bi deficient. Using Bi-rich targets stoichiometric films were obtained by depositing at substrate temperatures (typically in the range of 500 °–700 °C) high enough to prevent inclusion of the more volatile bismuth oxide in excess of theBi4Ti3O12composition. Good quality epitaxial growth has been achieved on MgO and epitaxial Pt substrates.

ISSN:0022-5355    

DOI:10.1116/1.1492894

出版商:American Vacuum Society    

年代:1970

数据来源: AIP

摘要:

Ultrahigh-vacuum systems are commonly provided with flanged openings that are sealed with copper gaskets. These systems must be baked to at least 250 °C in order to achieve ultrahigh vacuum. This paper presents an investigation of bakeable organic coatings that can be applied to copper gaskets to facilitate sealing conflat flanges on an ultrahigh-vacuum system. The coated gaskets have the advantage over uncoated gaskets in that they require fewer flange bolts and lower bolt torques to provide a leak-free seal. The coatings include polyimide and three silicones. Coating techniques, sealing parameters, and vacuum performance of the coated gasket seals are described. The sealing performance of the coating is characterized in terms of pumpdown performance and residual gas analyses. The results of this investigation show that these organic materials can be used for ultra-high-vacuum gasket coatings. They also show that little variation in the partial pressures of the residual gases (after bakeout) occurs when either uncoated or coated copper gaskets are used.

ISSN:0022-5355    

DOI:10.1116/1.1492896

出版商:American Vacuum Society    

年代:1970

数据来源: AIP