摘要:

Tin monocrystals have been bombarded with large doses([inverted lazy s]5×1017 particles/cm2)of 1.5–4‐MeV ions of H and He. Proton irradiations above 225 °C produce neither visible surface damage nor degradation of the ability of a crystal to channel the incident particles. Room‐temperature irradiations by H or He ions produce little observable damage near the crystal surfaces unless followed by post‐irradiation anneals to 220 °C or above. After such anneals, however, channeling measurements show permanent deterioration and the surfaces may show deformations such as swelling, blistering, and effervescence.

ISSN:0021-8979    

DOI:10.1063/1.1662375

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Antiphase boundaries (APB's) in ferroelastic‐ferroelectric Gd2(MoO4)3have been observed by etching single‐ and multiple‐domain crystals. These boundaries form closed loops, or terminate on dislocations, external surfaces, or on domain walls. They can be generated and annihilated by moving domain walls. Space‐group symmetry arguments show that APB's can exist in Gd2(MoO4)3. The crystals structure of ferroelastic‐ferroelectric Gd2(MoO4)3is discussed to describe the atomic distortions within domain walls and APB's. This qualitative analysis suggests that the free energy of an APB is of the order of the free energy of the domain wall.

ISSN:0021-8979    

DOI:10.1063/1.1662376

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Gallium was deposited on a tip specimen of a field ion microscope by making contact in vacuum. Gallium deposited on a tip area and diffused from the tip shank at 350 to 500 °K was crystallized in the pseudomorphic structure on tungsten. The number of atomic layers of the pseudomorphic gallium was 2 to 3. The sharp helium image of the pseudomorphic gallium appeared at a voltage considerably lower than the helium best‐image voltage for tungsten. The observed high evaporation field of the pseudomorphic gallium, 3.0–4.5 V/Å, may indicate that the gallium atoms in the pseudomorphic state are anomalously strongly bound to the substrate tungsten or are field evaporated as the doubly‐ionized ions. Various superstructures were observed on the {112} areas after heating above 900 °K, but their detailed structures did not depend upon temperature or heating time. An unidentified underlayer may play a dominant role in determining the structure of the superstructures. No clear evidence of alloy formation was noticed in the temperature range 21 to 1500 °K.

ISSN:0021-8979    

DOI:10.1063/1.1662377

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Gallium was deposited on a molybdenum tip by making contact between the tip and liquid gallium in vacuum. Pseudomorphic gallium could not be observed clearly. The product of the Mo&sngbnd;Ga reaction above 600 °C was found to be the ordered alloy, Mo3Ga, with the &bgr;‐W structure and no other structure was observed. The difference between the crystal structure and the observed image of the (001), (130), (120), and (110) planes of the alloy are explained by the unobservability of the gallium atom and by the variation of the stability of the molybdenum surface atoms. The observed differences in the stability of the surface atoms on these planes are interpreted in terms of anisotropic binding forces in the &bgr;‐W structure of the alloy.

ISSN:0021-8979    

DOI:10.1063/1.1662378

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The principal aim of this paper is to develop the theoretical and computational procedures used in the following paper. The Eikonal theory of crystal diffraction is summarized, and the computational procedures for obtaining the ray trajectory and the phase change along the ray in distorted crystals are described. Specifically, the x‐ray diffraction theory is applied to the analysis of dynamical diffraction effects observed by x‐ray topography at the edge of a thin oxide film superposed on a silicon host crystal. The critical importance of symmetry properties of topographs in evaluating the computational procedures is emphasized. The present computational procedures are quite general and can be used with appropriate modifications for a quantitative understanding of diffraction effects, due to any general distortion in crystals observed in topographs of the section type.

ISSN:0021-8979    

DOI:10.1063/1.1662379

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The computational and theoretical procedures developed in the preceding paper are applied to the problem of x‐ray dynamical diffraction effects observed at the edges of a thin oxide film thermally grown on highly perfect silicon. The experimental observations have mainly been of the section type which reveal the fine details of the diffraction phenomena as extra hook‐shaped ``Pendello¨sung'' fringes in the silicon crystal. The observed position of the fringes and their phases agree reasonably well with theoretical calculations. Measurements have been made for a number of thicknesses of oxide film grown under different conditions. From the analysis it is possible to evaluate the stress in the film. The results indicate that for oxides grown at different temperatures and under different conditions, the stress in the film is constant. Possible implications of this result with regard to the thermal history of the oxide are discussed.

ISSN:0021-8979    

DOI:10.1063/1.1662380

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The structural, chemical, and photoelectronic properties are compared for three types of chemically deposited lead sulfide film. The film types differ in the use of an oxidant during the deposition. The films are grainy in structure and show a decrease in grain compaction as the concentration of the oxidant is increased. Nominal chemical composition, including the concentration of oxygen, is not significantly dependent on the use of the oxidant. Photosensitive films may be described in terms of sensitizing centers which are present only when an oxidant is used but which are not dependent solely on the presence of oxygen. The physical identification of the sensitizing centers has not been determined but may be associated with film structure.

ISSN:0021-8979    

DOI:10.1063/1.1662381

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

An explicit expression is derived for the indentation hardness numbers of alkali halide crystals in terms of ionic binding, combined with the theory of plastic indentation. The resistance to indentation is caused by the electrostatic faults that exist at the cores of {100} ⟨1¯10⟩ dislocations. The theoretical hardness is given by (cgs units)H0=0.096(e2/&egr;b4)= 1.2×10−2C44, whereeis the electron charge, &egr; is the static dielectric constant,bis the Burgers displacement, andc44is the elastic shear stiffness. The theoretical hardness for NaCl is 17 kg/mm2compared with the observed value of 16.7 kg/mm2.

ISSN:0021-8979    

DOI:10.1063/1.1662382

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The thermoelectret and photoelectret studies have been performed in detail in a natural plant product, Boswellia Glabra [BG(Y)] and its mixture with ZnO. Thermoelectret effect in this material is comparable with any other material. The permanent homocharge formation in the higher fields restricts the upper limit to which the photosensitive paper, with BG(Y) binders, can be charged. The photoelectret studies of this material show that it possesses a slow dark decay and a fast light decay when it is mixed with ZnO, which are the essential requirements for photosensitive mixtures. The ZnO‐BG(Y) combination does not deteriorate the charge acceptance property of ZnO. Mixed with proper sensitizers for visible light, the ZnO‐BG(Y) mixture is found to be suitable for photosensitive coating for direct electrophotographic‐image processing systems.

ISSN:0021-8979    

DOI:10.1063/1.1662383

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Investigations of the reaction kinetics of the deposition of silica and phosphosilicate glasses were made to determine the parameters governing the rates of reactions. Dependence of deposition rates on substrate temperature shows that the reactions obey the absolute rate theory of heterogeneous reactions at a solid surface. The silane oxidation reaction is of half‐order with respect to oxygen, of half‐order with respect to silane, and of first‐order over‐all. The phosphine oxidation reaction is of second‐order over‐all. The unusual decrease in deposition rate with increasing oxygen concentrations, during the oxidation of silane, has been shown to originate from the adsorption of oxygen on the silicon substrates, retarding the reaction.

ISSN:0021-8979    

DOI:10.1063/1.1662384

出版商:AIP    

年代:1973

数据来源: AIP