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. A preliminary thermoanalytical study on Bi-Se composites were conducted via [[Thermogravimetric analysis|thermogravimetry]] (TG) and differential thermogravimetry (DTG) experiments using 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, 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.<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>

== 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]]