Defects crystallographic

Intrinsic failures are inherent in the design and materials used rather than being caused by an interaction of a stress with some defect. Intrinsic failures are typically wear-out failures, and hence these define the design life. Extrinsic failures are due to process defects, e.g., electrical and environmental stresses. Product reliability may be determined by the extrinsic failure rate. Production defects crystallographic defects, photolithography, surface contamination, oxide defects, packaging defects. 

Structure and spectroscopy. The structure of a high-surface area oxide is traditionally described on the basis of spectroscopic information and by the application of models derived from structures of perfect or defective crystallographic planes. Vibrational and optical spectroscopies are employed to detect hydroxyl groups and low coordination oxide ions, respectively, on pure oxide surfaces. VJhen... 

When plastic deformation occurs, crystallographic planes sHp past each other. SHp is fackitated by the unique atomic stmcture of metals, which consists of an electron cloud surrounding positive nuclei. This stmcture permits shifting of atomic position without separation of atomic planes and resultant fracture. The stress requked to sHp an atomic plane past an adjacent plane is extremely high if the entire plane moves at the same time. Therefore, the plane moves locally, which gives rise to line defects called dislocations. These dislocations explain strain hardening and many other phenomena. 

The piopeities of a ceramic material that make it suitable for a given electronic appHcation are intimately related to such physical properties as crystal stmcture, crystallographic defects, grain boundaries, domain stmcture, microstmcture, and macrostmcture. The development of ceramics that possess desirable electronic properties requires an understanding of the relationship between material stmctural characteristics and electronic properties and how processing conditions maybe manipulated to control stmctural features. 

A pecuhar sohd phase, which has been discovered not too long ago [172], is the quasi-crystalline phase. Quasi-crystals are characterized by a fivefold or icosahedral symmetry which is not of crystallographic type and therefore was assumed to be forbidden. In addition to dislocations which also exist in normal crystals, quasi-crystals show new types of defects called phasons. Computer simulations of the growth of quasicrystals [173] are still somewhat scarce, but an increasing number of quasi-crystalline details are studied by simulations, including dislocations and phasons, anomalous self-diffusion, and crack propagation [174,175]. 

For pc-Au/electrolyte interfaces, Clavilier and Nguyen Van Huong256 also concluded that the crystallographic inhomogeneity factor depends on ce. Later, the influence of the crystallographic inhomogeneity of pc and monocrystalline electrodes (with various surface defects) was discussed in many papers.75,152,154 156 247-259 It has been shown that the potential of the diffuse-layer capacitance minimum for a polycrystalline electrode does not correspond to Ea=Q of the whole surface, i.e., 2J 0,< 0 at E n. 

Cul) is not due to point defects but to partial occupation of crystallographic sites. The defective structure is sometimes called structural disorder to distinguish it from point defects. There are a large number of vacant sites for the cations to move into. Thus, ionic conductivity is enabled without use of aliovalent dopants. A common feature of both compounds is that they are composed of extremely polarizable ions. This means that the electron cloud surrounding the ions is easily distorted. This makes the passage of a cation past an anion easier. Due to their high ionic conductivity, silver and copper ion conductors can be used as solid electrolytes in solid-state batteries. 

At smooth metal electrodes that have been subjected to annealing, the number of different crystallographic defects (dislocations, kinks, etc.) emerging at the surface is between 10 and lO cm. This number is small relative to the total number of surface atoms (which is on the order of 10 cm ). In the literature, attempts have been described to determine the catalytic activity of electrodes having an artihcially boosted number of surface defects. These experiments gave no unambiguous results in some cases some increase, in other cases some decrease in activity was observed. 

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