Optical properties of selenium: Difference between revisions

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*#REDIRECT [[Selenium]]

{{too technical|date=November 2017}}

[[File:SeBlackRed.jpg|thumb|right|Black, glassy amorphous, and red amorphous selenium]]

'''[[Selenium]]''' powder is an [[amorphous]], brick-red powder that may become black upon exposure to air,<ref>{{Cite web|url=https://cameochemicals.noaa.gov/chemical/4427|title=SELENIUM POWDER {{!}} CAMEO Chemicals {{!}} NOAA|last=GOV|first=NOAA Office of Response and Restoration, US|website=cameochemicals.noaa.gov|access-date=2017-11-06}}</ref> while vitreous ingots and films/crystals are black,<ref>{{Cite book|url=https://doi.org/10.1007/978-1-4613-2655-7|title=Dictionary of Ceramic Science and Engineering {{!}} SpringerLink|last=O’Bannon|first=Loran S.|language=en-gb|doi=10.1007/978-1-4613-2655-7}}</ref> with physical properties divided into structural, [[Optics|optical]], [[Electricity|electrical]], and [[dielectric]]. Its behavior to various external agents are of importance from basic research and technical points of view.

==Optical properties==

There are several approaches to analyze transmittance data of selenium films, from which one can extract their optical constants and other related topics.<ref>{{Cite journal|last=Jafar|first=Mousa M. Abdul-Gader|last2=Saleh|first2=Mahmoud H.|last3=Ahmad|first3=Mais Jamil A.|last4=Bulos|first4=Basim N.|last5=Al-Daraghmeh|first5=Tariq M.|date=2016-04-01|title=Retrieval of optical constants of undoped amorphous selenium films from an analysis of their normal-incidence transmittance spectra using numeric PUMA method|url=https://link.springer.com/article/10.1007/s10854-015-4156-z|journal=Journal of Materials Science: Materials in Electronics|language=en|volume=27|issue=4|pages=3281–3291|doi=10.1007/s10854-015-4156-z|issn=0957-4522}}</ref> However, the algebraic method of Swanepoel envelope method (EM) seems to be trustful and need no dispersion relations in prior, but is limited to transmittance spectra that display a number of peaks (maxima and minima).<ref>{{Cite journal|last=Saleh|first=Mahmoud H.|last2=Ershaidat|first2=Nidal M.|last3=Ahmad|first3=Mais Jamil A.|last4=Bulos|first4=Basim N.|last5=Jafar|first5=Mousa M. Abdul-Gader|date=2017-06-01|title=Evaluation of spectral dispersion of optical constants of a-Se films from their normal-incidence transmittance spectra using Swanepoel algebraic envelope approach|url=https://link.springer.com/article/10.1007/s10043-017-0311-5|journal=Optical Review|language=en|volume=24|issue=3|pages=260–277|doi=10.1007/s10043-017-0311-5|issn=1340-6000}}</ref> However, EM method has a further limitation that is only of good validity in a wide spectral region in the quasi-transparency <ref>{{Cite web|url=https://www.researchgate.net/publication/272292433_Comprehensive_formulations_forthe_total_normal-incidence_optical_reflectance_and_transmittance_of_thin_films_laid_on_thick_substrates|title=Comprehensive formulations forthe total normal-incidence optical reflectance and transmittance of thin films laid on thick substrates|website=ResearchGate|language=en|access-date=2017-11-06}}</ref><ref>{{Cite journal|last=Minkov|first=D.A.|last2=Gavrilov|first2=G.M.|last3=Angelov|first3=G.V.|last4=Moreno|first4=J.M.D.|last5=Vazquez|first5=C.G.|last6=Ruano|first6=S.M.F.|last7=Marquez|first7=E.|title=Optimisation of the envelope method for characterisation of optical thin film on substrate specimens from their normal incidence transmittance spectrum|url=https://doi.org/10.1016/j.tsf.2017.11.003|journal=Thin Solid Films|doi=10.1016/j.tsf.2017.11.003}}</ref> Conventional curve-fitting of the transmittance data, an approach that depends on the availability of proper dispersion formulas to be inserted in the program, usually yield multi-solutions of the problem (that is, local solutions, from which different, sometimes unrealistic, fitting parameters and care should be taken to choose the correct results, and only a global solution of the problem gives physically-meaningful results.<ref>{{Cite journal|last=Saleh|first=Mahmoud H.|last2=Jafar|first2=Mousa M. Abdul-Gader|last3=Bulos|first3=Basim N.|last4=Al-Daraghmeh|first4=Tariq M. F.|date=2014-10-21|title=Determination of Optical Properties of Undoped Amorphous Selenium (a-Se) Films by Dielectric Modeling of Their Normal-Incidence Transmittance Spectra|url=http://www.ccsenet.org/journal/index.php/apr/article/view/40452|journal=Applied Physics Research|language=en|volume=6|issue=6|pages=10|doi=10.5539/apr.v6n6p10|issn=1916-9647}}</ref>

== Thermoanalytical properties ==

[[Stoichiometry|Stoichiometric]] films of selenium-based alloys such as those of Bi-Se and Bi-Te composites are of technical importance for applications in [[memory switch devices]]. Thermoanalytical studies often give information about their stoichiometry, melting/boiling points and kinetic reactions responsible for their decomposition and crystallization. Thermoanalytical study on Bi-Se composites using [[Thermogravimetric analysis|thermogravimetry]] (TG) and differential thermogravimetry (DTG) experiments with a single heating rate and analyzing the measured non-isothermal TG and DTG curves via model-based [[Fictitious force|kinetic reaction]] formulas of original Coats-Redfern (CR) and Achar-Brindley-Sharp (ABS) equations yields promising results on the nature of kinetic reaction models operational in such systems.<ref>{{Cite journal|last=Ahmad|first=Mais Jamil A.|last2=Jafar|first2=Mousa M. Abdul-Gader|last3=Saleh|first3=Mahmoud H.|last4=Shehadeh|first4=Khawla M.|last5=Telfah|first5=Ahmad|last6=Ziq|first6=Khalil A.|date=2017-09-30|title=Evaluation of Kinetic Parameters and Thermal Stability of Melt-Quenched Bi_xSe_100−x Alloys (x ≤7.5 at%) by Non-Isothermal Thermogravimetric Analysis|url=http://www.appmicro.org/journal/view.html?uid=223&&vmd=Full|journal=Applied Microscopy|language=en|volume=47|issue=3|doi=10.9729/AM.2017.47.3.110|issn=2287-5123}}</ref> , though it is always preferable to analyze such TG and DTG data on the basis of model-free kinetic reaction formulations and several heating rates, in addition to performing differential scanning calorimetric (DSC) and differential temperature analysis (DTA) which usually give more information on crystallinity contents as well as important thermal properties

== Electric and dielectric properties ==

Electrical and dielectric behavior of undoped amorphous and crystalline selenium films, as well as Se-based composites often , in which their structure and electric/dielectric properties/data have been also investigated and analyzed.<ref>{{Cite journal|last=Abdul-Gader Jafar|first=M. M.|last2=Nigmatullin|first2=R. R.|date=2001-09-21|title=Identification of a new function model for the AC-impedance of thermally evaporated undoped selenium films using the Eigen-coordinates method|url=http://www.sciencedirect.com/science/article/pii/S004060900101166X|journal=Thin Solid Films|volume=396|issue=1|pages=282–296|doi=10.1016/S0040-6090(01)01166-X}}</ref> <ref>{{Cite journal|last=ABDUL-GADER|first=M. M.|last2=AL-BASHA|first2=MAHMOUD A.|last3=WISHAH|first3=K. A.|date=1998-07-01|title=Temperature dependence of DC conductivity of as-deposited and annealed selenium films|url=http://dx.doi.org/10.1080/002072198134328|journal=International Journal of Electronics|volume=85|issue=1|pages=21–41|doi=10.1080/002072198134328|issn=0020-7217}}</ref> <ref>{{Cite journal|last=I.F.|first=Al-Hamarneh,|last2=B.N.|first2=Bulos,|last3=Abdul-Gader|first3=Jafar, M.M.|title=Effect of isothermal annealing and visible-light illumination on the AC-impedance behavior of undoped selenium thin films|url=http://www.academia.edu/30276102/Effect_of_isothermal_annealing_and_visible-light_illumination_on_the_AC-impedance_behavior_of_undoped_selenium_thin_films|journal=Journal of Non-Crystalline Solids|language=en|volume=355|issue=4-5|issn=0022-3093}}</ref>

==See also==

*[[Selenium]]

*[[Selenium-79]]

*[[Isotopes of selenium]]

==References==

{{reflist}}

{{sci-stub}}

[[Category:Selenium]]