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Article Citation - WoS: 19Citation - Scopus: 19Poly(3,4-Alkylenedioxyselenophene)s: Past, Present, and Future(Georg Thieme verlag Kg, 2015) Cihaner, AtillaBecause of their optical and electronic properties, polythiophenes and their derivatives, especially poly(3,4-alkylenedioxythiophene)s, are among the most promising materials in the field of electrochromic polymers. The properties of these polymers can be tuned by replacing the sulfur atom of the thiophene moiety with a selenium atom, because selenium has a lower electronegativity, a higher metallic character, a larger atomic size, and greater polarizability than sulfur. This approach has opened the door to a new and vibrant class of conjugated polymers. Today 3,4-alkylenedioxyselenophenes are thought as powerful competitors to 3,4-alkylenedioxythiophenes. Here, an overview is presented of poly(3,4-alkylenedioxyselenophene)s, as one of the most attractive groups of conjugated polymers. The design, synthesis, and applications of poly(3,4-alkylenedioxyselenophene)s and their derivatives are discussed in detail and compared with the corresponding features of their thiophene analogues. The electrochemical and electrochromic properties and band gaps of poly(3,4-alkylenedioxyselenophene) s are also discussed in relation to their chemical structures. 1 Introduction 2 Polyselenophenes 3 Poly(3,4-ethylenedioxyselenophene)s 4 Poly(3,4-propylenedioxyselenophene)s 5 ConclusionsArticle Citation - WoS: 4Citation - Scopus: 5Electrical Characterization of Bi1.50-x< Varactors(World Scientific Publ Co Pte Ltd, 2014) Qasrawi, A. F.; Abu Muis, Khalil O.; Abu Al Rob, Osama H.; Mergen, A.The electrical properties of yttrium doped bismuth zinc niobium oxide (BZN) pyrochlore ceramics are explored by means of temperature dependent electrical conductivity dielectric constant and capacitance spectra in the frequency range of 0-3 GHz. It is observed that the doped BZN exhibit a conductivity type conversion from intrinsic to extrinsic as the doping content increased from 0.04 to 0.06. The thermal energy bandgap of the intrinsic type is 3.45 eV. The pyrochlore is observed to exhibit a dielectric breakdown at 395 K. In addition, a negative capacitance (NC) spectrum with main resonance peak position of 23.2 MHz is detected. The NC effect is ascribed to the increased polarization and the availability of more free carriers in the device. When the NC signal amplitude is attenuated in the range of 0-20 dBm at 50 MHz and 150 MHz, wide tunability is monitored. Such characteristics of the Y-doped BZN are attractive for using them to cancel the positive parasitic capacitance of electronic circuits. The canceling of parasitic capacitance improves the high frequency performance of filter inductors and reduces the common mode noise of the resonance signal.
