Karakterizacija termoindukovanih procesa i strukturne jedinice u nekim halkogenidnim staklima

Abstract

<p>Predmet istraživanja u okviru doktorske teze je uticaj prisustva metala ili&nbsp;metaloida u amorfnim sistemima As-S(Se)-I na termoindukovane procese i&nbsp;strukturne jedinice u njihovoj mreži. Pokazano je da, u zavisnosti od&nbsp;halkogenidnog sistema, različiti primesni atomi različito reaguju i ugrađuju se&nbsp;u matricu stakla formiranjem različitih strukturnih jedinica. U tom smislu,&nbsp;izabrani su binarni i kvazibinarni preseci klasičnih halkogenidnih sastava i&nbsp;ispitivan je, s jedne strane, uticaj izmene srodnih hemijskih elemenata (As-Sb), a s druge, uvođenje Cu i Fe u amorfnu matricu na ispitivana svojstva.&nbsp;Zamena As i Sb vr&scaron;ena je u okviru sistema Sb_xAs_37-xS₄₈I₁₅. Bakar je uvođen u&nbsp;amorfnu matricu As₂Se₃, tako da su analizirane promene ispitivanih osobina&nbsp;sa promenom sastava stakla iz sistema Cu_x(As₂Se₃)_100-x. Pona&scaron;anje atoma Fe&nbsp;ispitivano je u okviru sistema Fe_x[(Sb₂S₃)_0.75(SbI₃)_0.25]_100-x. DSC merenjima&nbsp;pri različitim brzinama zagrevanja izvr&scaron;ena&nbsp; je kvalitativna i kvantitativna&nbsp;karakterizacija termoindukovanih procesa u smislu određivanja temperatura&nbsp;na kojima se ovi procesi odvijaju, odgovarajućih promena specifičnog&nbsp;toplotnog kapaciteta pri razmek&scaron;avanju, mehanizama kristalizacije i kristalnog&nbsp;rasta, vrednosti Avramijevog parametra, vrednosti parametara termičke&nbsp;stabilnosti i energetski efekti svih procesa, detekcija prisutnih strukturnih&nbsp;jedinica. Ramanova spektroskopija potvrdila je prisustvo detektovanih&nbsp;<span style="font-size: 12px;">strukturnih jedinica i promene u strukturi i na taj način dopunila rezultate&nbsp;</span>termičkih merenja. U krajnjoj istanci određeno je kako uvođenje prelaznog metala ili metaloida utiče na tok i vrstu faznih transformacija u staklu, kakvi mehanizmi ugrađivanja primesnih atoma u amorfnu matricu postoje i kako je taj mehanizam uslovljen prirodom primesnih atoma i same matrice.</p>

<p>Subject of research in the doctoral thesis is the effect of the metal or&nbsp;metalloid in As-S (Se)-I amorphous systems onto thermally induced&nbsp;processes and the structural units intheir network. It is shown that,&nbsp;depending on the chalcogenide system, different admixtures atoms react&nbsp;differently and are embedded in a glass matrix by formation of different&nbsp;structural units. In this regard, binary and quasi-binary sections of&nbsp;classical chalcogenide compositions are chosen and investigated, on the&nbsp;one hand, the impact of substitution of similar chemical elements (As-Sb), and on the other hand, the introduction of Cu and Fe in the&nbsp;amorphous matrix of the investigated properties. As and Sb substitution is&nbsp;performed within the Sb_xAs_{37- x}S₄₈I₁₅system. Copper is introduced into an&nbsp;As₂Se_3&nbsp;amorphous matrix, so that the investigated properties are analyzed&nbsp;depending on the composition changes in the system Cu_x(As₂Se₃)_100-x.&nbsp;The behavior of Fe atoms is studied in the Fe_x[(Sb₂S₃)_0.75(SbI₃)_0.25]_100-x&nbsp;system. DSC measurements at different heating rates &nbsp;are used to&nbsp;performed qualitative and quantitative characterization of thermally&nbsp;induced process in terms of determining the temperatures at which these&nbsp;processes take place, corresponding changes of the specific heat capacity&nbsp;at the glass transition, crystallization mechanism and crystal growth,&nbsp;value of the Avrami parameter, the values of thermal stability parameter and energy effects of all &nbsp;processes, the detection of structural units present. Raman spectroscopy confirmed the presence of detected structural units and changes in the structure and thus complemented the results of thermal measurements. Finally, it is determined that the introduction of transition metals or metalloids influence the course of the phase transformation in the glass, the mechanisms of incorporation of doping atoms in the amorphous matrix and that there is a mechanism that depends on the nature of the doping atoms and the matrix.&nbsp;</p>