摘要:

The angular distribution of material sputtered under normal Hg+‐ion incidence from flat, polycrystalline targets at 100 to 1000 ev was measured and plotted in polar diagrams. The distribution is ``under cosine,'' approaching a cosine distribution, at higher ion energies. Mo and Fe show a more pronounced tendency to eject to the sides than Ni or Pt. Under oblique ion incidence atoms are sputtered preferentially in the forward direction.

ISSN:0021-8979    

DOI:10.1063/1.1735395

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The characteristic properties of the displacement current transients obtained from ferroelectric colemanite crystals during polarization reversal are presented in detail. A phenomenological and semiempirical model of the switching mechanism is proposed. The model yields good agreement with the switching current dependence upon time, field amplitude and ambient temperature. It is based upon random nucleation followed by extensive sidewise displacement of the nucleated 180° domains. A model based upon three dimensional growth of nucleated domains is shown to be in poor agreement with experiment.

ISSN:0021-8979    

DOI:10.1063/1.1735396

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Lead zirconate titanate ceramics with certain 3‐ or 5‐valent additions (lanthanum, neodynium, tantalum, and niobium) are found to be characterized by low aging of electrical and mechanical properties, a well‐defined hysteresis loop, and by high electrical and mechanical losses. Experimental investigations are reported on plain lead zirconate titanate and on a low‐aging niobium modification.The experiments included an electron microscope study of the ceramics and a number of electrical measurements. As a result of the study, the changed properties of the substituted material have been explained as being due to domain wall motion under low electric field. The results of electrical measurements supporting this conclusion, and a hypothesis accounting for the effects in terms of lattice vacancies, are presented.The 3‐ or 5‐valent additives described in the foregoing also cause greatly increased volume resistivity in the ceramic. This has not been satisfactorily explained.

ISSN:0021-8979    

DOI:10.1063/1.1735397

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Details of dislocation structure have been determined for a variety of NaCl whiskers and microcrystals grown from porous substrates moistened with supersaturated aqueous solution. Some of the smaller needle‐like crystals have the single dislocation with an axial screw component usually assumed for whiskers. Larger whiskers and platelets often have much more complicated dislocation structures and may have higher dislocation densities than normal bulk crystals. Strengths were compared with dislocation structures and it was found that the nearly theoretical strengths observed in some of these whiskers are not due to merely a size effect but are directly related to the dislocation structure. Even crystals with high dislocation densities exhibited high strength in bending provided that all of the dislocations were so arrayed that they were not influenced by the applied stress. Regular dislocation arrays often occur naturally with this growth mechanism. However, irregular dislocation structures often associated with growth irregularities invariably resulted in low strength. Techniques for application of x‐ray diffraction microscopy to determination of the dislocation structure of microcrystals are described.

ISSN:0021-8979    

DOI:10.1063/1.1735398

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Capillary rise of a saturated solution within a hollow whisker has been found to provide a mechanism yielding growth at the tips of cesium chloride whiskers on a moist substrate in air at room temperature. The driving force for crystal growth is local supersaturation due to evaporation of water from solution at the tip of the capillary pore in each whisker. Screw dislocations provide the lattice steps on the whisker tips.

ISSN:0021-8979    

DOI:10.1063/1.1735399

出版商:AIP    

年代:1960

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1735400

出版商:AIP    

年代:1960

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1735402

出版商:AIP    

年代:1960

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1735403

出版商:AIP    

年代:1960

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1735404

出版商:AIP    

年代:1960

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1735406

出版商:AIP    

年代:1960

数据来源: AIP