Ferroelectrics semiconductor

PLD of crystalline and stoichiometric ferroelectric materials has been successful for a number of materials. For example, crystaUine PbTiOs thin films have been deposited at only 350 °C using a KrF excimer laser (A. = 248 mn). The low deposition temperature makes this a potentially attractive method for directly fabricating ferroelectric/semiconductor hybrid devices. A related solid that is more difficult to prepare in thin film form is PbZri- ThOs. To maintain the Pb stoichiometry and ensure random mixing of Ti and Zr requires careful control of film synthesis conditions. ... 

Fig. 3. An overview of atomistic mechanisms involved in electroceramic components and the corresponding uses (a) ferroelectric domains capacitors and piezoelectrics, PTC thermistors (b) electronic conduction NTC thermistor (c) insulators and substrates (d) surface conduction humidity sensors (e) ferrimagnetic domains ferrite hard and soft magnets, magnetic tape (f) metal—semiconductor transition critical temperature NTC thermistor (g) ionic conduction gas sensors and batteries and (h) grain boundary phenomena varistors, boundary layer capacitors, PTC thermistors.

The potassium salts are the most soluble and other salts usually are precipitated by addition of the appropriate metal chloride to a solution of the corresponding potassium salt. The metaniobates, MNbO, and orthoniobates, MNbO, generally are prepared by fusion of the anhydrous mixed oxides. The metaniobates crystallize with the perovskite stmeture and are ferroelectric (131) (see Ferroelectrics). The orthoniobates are narrow band-gap semiconductors (qv) (132). 

Nonoxide NLO ceramics include Si and compound semiconductors (qv) having the silicon stmcture, eg, GaAs, InP, and InSb, as weU as ferroelectrics such as SbSI. These materials tend to be more highly nonlinear than oxide ceramics, although lack of transparency at visible and uv wavelengths prevents them from competing with the oxides for the same appHcations. 

The term photovoltaic effect is further used to denote non-electrochemical photoprocesses in solid-state metal/semiconductor interfaces (Schottky barrier contacts) and semiconductor/semiconductor pin) junctions. Analogously, the term photogalvanic effect is used more generally to denote any photoexcitation of the d.c. current in a material (e.g. in solid ferroelectrics). Although confusion is not usual, electrochemical reactions initiated by light absorption in electrolyte solutions should be termed electrochemical photogalvanic effect , and reactions at photoexcited semiconductor electodes electrochemical photovoltaic effect . 

Bipolar plates, MCFC, 12 223 Bipolar transistors, silicon based semiconductors in, 22 246-249 Bipolymers, 20 533, 534 Bipropellants, 10 727 Bipyridines, uses for, 21 127 Bipyridinium herbicides, 13 315 Bipyridium, 24 51 Bipyridyl trimers, 24 50 Biquinolines, 21 200 Birefringence, 14 675, 680 19 745 in ferroelectric crystals, 11 94 polycarbonate, 19 822 of regenerated cellulose fibers,... 

A photomultiplier tube is a sensitive detector of visible and ultraviolet radiation photons cause electrons to be ejected from a metallic cathode. The signal is amplified at each successive dynode on which the photoelectrons impinge. Photodiode arrays and charge coupled devices are solid-state detectors in which photons create electrons and holes in semiconductor materials. Coupled to a polychromator, these devices can record all wavelengths of a spectrum simultaneously, with resolution limited by the number and spacing of detector elements. Common infrared detectors include thermocouples, ferroelectric materials, and photoconductive and photovoltaic devices. 

A general review of photorefractive materials was presented in 1988. 150) Also, two monographs in were published which detail theory, physical characterization and practice of the use of known photorefractives.(151) Three classes of inorganic materials dominate. Ferroelectric oxides, such as LiNbC>3 and BaTiC>3 mentioned above compound semiconductors such as GaAs and InP, and the sillenite family of oxides, exemplified by Bii2SiC>20 and Bii2TiC>20 The semiconductors are sensitive only in the infrared, while the other materials operate in the... 

The aforementioned frequency of the use of these nanomaterial shapes is best attributed to two factors (1) the ease with which these nanoparticle shapes can be synthesized in the laboratory and (2) the availability of these nanomaterials from commercial sources. It cannot be the aim of this review to cover all of the different nanomaterials used so far, but some of the most commonly investigated will be introduced in more detail. For zero-dimensional nanoparticles, emphasis will be put on metallic nanoparticles (mainly gold), semiconductor quantum dots, as well as magnetic (different iron oxides) and ferroelectric nanoparticles. In the area of onedimensional nanomaterials, metal and semiconductor nanorods and nano wires as well as carbon nanotubes will be briefly discussed, and for two-dimensional nanomaterials only nanoclay. Finally, researchers active in the field are advised to seek further information about these and other nanomaterials in the following, very insightful review articles [16, 36-45]. 

Fp, as observed. At lower T, non-linearity in the free energy functional is expected to favor sharp domain walls [21], The transition to the monodomain ferroelectric phase F1 has been predicted by treating the ferroelectric as a semiconductor, in which carriers can be created by the field effect [16]. This transition can be calculated to occur at Tc - T = 325 K for d = 10 nm [4], in qualitative agreement with our observations. The rich phase diagram we have observed in this simple system makes it an excellent test case for more quantitative development of these concepts. 

Later, the evolution of the electronic industry initiated the development of an immense variety of materials and devises based, essentially, on the properties of semiconductor, dielectric, ferromagnetic, superconductor, and ferroelectric materials. 

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