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The influence of inclusions on phase transformations of framework aluminosilucates

dc.contributor.advisorDondur, Vera
dc.contributor.otherDamjanović, Ljiljana
dc.contributor.otherĆirić-Marjanović, Gordana
dc.contributor.otherVulić, Pedrag
dc.creatorRadulović, Aleksandra M.
dc.date.accessioned2016-01-05T12:46:12Z
dc.date.available2016-01-05T12:46:12Z
dc.date.available2020-07-03T09:34:34Z
dc.date.issued2013-06-24
dc.identifier.urihttp://eteze.bg.ac.rs/application/showtheses?thesesId=909
dc.identifier.urihttp://nardus.mpn.gov.rs/handle/123456789/3017
dc.identifier.urihttps://fedorabg.bg.ac.rs/fedora/get/o:7427/bdef:Content/download
dc.identifier.urihttp://vbs.rs/scripts/cobiss?command=DISPLAY&base=70036&RID=44742671
dc.description.abstractIako termalno indukovane transformacije mrežnih alumosilikata daju jedinstven metod za formiranje novih faza sa poboljšanim osobinama, zbog kompleksnosti samog procesa, mehanizam konverzije još uvek nije u potpunosti razjašnjen. Usled male jedinične ćelije (Na12Si12Al12O4827H2O) i dobro proučene mrežne strukture i raspodele van-mrežnih katjona, zeolit Na-LTA predstavlja model supstancu za ispitivanje promena u uređenju na kratkom, srednjem i dugom dometu u procesu termalnih transformacija zeolita u popunjene derivate SiO2 polimorfa. Iako su još prva istraživanja pokazala da svaki sintetisan Na-LTA zeolit nije čist u kristalografskom smislu i u zavisnosti od uslova sinteze sadrži različite količine Na, Al i Si inkluzija unutar  i  kaveza, u literaturi ne postoje podaci o katalitičkom uticaju ovih vrsta na mehanizam termalne konverzije Na-LTA zeolita. Prezentovana teza sumira rezultate istraživanja uticaja Na, Al i Si inkluzija na mehanizam termalno indukovanih transformacija Na-LTA zeolita u karnegitske i nefelinske polimorfe. U prvom delu teze opisan je potupak sinteze Na-LTA zeolita sa različitim sadržajem Na, Al i Si inkluzija. Ispitan je uticaj variranja Na2O : Al2O3 : SiO2 odnosa u polaznoj reakcionoj smeši na stehiometriju sintetisanih Na-LTA zeolita i morfologiju kristalnih zrna. Kao postupak uklanjanja inkluzija zaostalih u Na-LTA zeolitima nakon sinteze, predložen je tretman refluksovanja Na-LTA zeolita na 100 ºC, koji ne izaziva amorfizaciju i dodatne strukturne promene u Na-LTA zeolitima. Drugi deo teze fokusiran je na ispitivanje uticaja Na, Al i Si inkluzija na termalnu stabilnost Na-LTA zeolita i njegovu konverziju u karnegitske i nefelinske polimorfe. Posebna pažnja je posvećena ispitivanju mehanizma fazne transformacije Na-LTA zeolita u nisko-temperaturni karnegit koji je u literaturi prezentovan dvema različitim šemama: kao direktna topotaktička transformacija Na-LTA → nisko-temperaturni karnegit i kao dvostepeni mehanizam Na-LTA → Amorfna faza → nisko-temperaturni karnegit. Metodama XRPD, DTA i IR spektroskopije je utvrđeno da Na i Al inkluzije podstiču fazni prelaz Na-LTA zeolita u nisko-temperaturni karnegit uz nemogućnost detekcije kolapsa LTA mreže u amorfnu strukturu, izazivajući brzo raskidanje i formiranje novih veza, pri čemu brzina termalne transformacije raste sa povećanjem sadržaja Al. Sa druge strane, u slučaju faznog prelaza refluksom tretiranih Na-LTA zeolita idealne stehiometrije u niskotemperaturni karnegit, utvrđen je kolaps LTA mreže u stabilnu amorfnu strukturu iz koje je zatim kristalisala faza nisko-temperaturnog karnegita. Karakterizacijom amorfne NaAlSiO4 faze infracrvenom i ramanskom spektroskopijom, utvrđeno je prisustvo četvoročlanih i šestočlanih tetraedarskih prstenova čime je zaključeno da su kolapsom zeolita u amorfnu fazu zadržani fragmenti LTA mreže, što može biti polazna osnova u sintezi „perfektnih“ stakala. Na višim temperaturama, ispitani su uslovi formiranja nefelinskih struktura, rekonstruktivnom faznom transformacijom nisko-temperaturnog karnegita, što je usled velikog broja nefelinskih polimorfa različite simetrije, veoma aktuelna problematika. Rezultati ispitivanja su pokazali da Na, Al i Si inkluzije u Na-LTA zeolitu uslovljavaju transformaciju nisko-temperaturnog karnegita u smešu monokliničnog trinefelina i osnovnog heksagonalnog nefelina, dok se u procesu termalno indukovanih transformacija refluksom tretiranih zeolita idealne LTA stehiometrije, formira faza čistog osnovnog heksagonalnog nefelina. Takođe, ispitani su uslovi termalne konverzije monokliničnog trinefelina u osnovni heksagonalni nefelin. U prisustvu Na i Si inkluzija sintetisana je intermedijerna faza nefelinskog („ABABAB...“) strukturnog tipa koja nije mogla biti identifikovana na osnovu poznatih nefelinskih struktura. Razlike u uređenju na kratkom i srednjem dometu visokotemperaturnih NaAlSiO4 polimorfa dobijenih termalnom konverzijom Na-LTA zeolita različite stehiometrije, pripisane su uticaju Na, Al i Si inkluzija u kavezima zeolita. Ovim istraživanjem predloženo je da Na-LTA zeolit predstavlja primer mnogo šireg problema uticaja nestehiometrije na tok i mehanizam termalno indukovanih transformacija zeolita, kao i da se isti zaključci mogu primeniti i na druge tipove zeolita koji sadrže različite van-mrežne katjone.sr
dc.description.abstractAlthough thermally induced transformations of framework aluminosilicates provide unique method for synthesis of materials with advanced properties, conversion mechanism is not explained yet because of the complexity of the process. Because of the small unit cell (Na12Si12Al12O4827H2O) and well known framework structure and extra-framework cation distribution, zeolite Na-LTA represents ideal model for investigation of changes in the short, middle and long range order, in the processes of zeolite thermal transformation into stuffed derivatives of SiO2 polymorphs. Even though investigations showed that Na-LTA zeolite is not pure from crystallographic point of view and, depending on synthesis procedure, contains different amounts of Na, Al and Si inclusions inside α and β cages, there are no data regarding catalytic influence of these species on the mechanism of thermal conversions. Presented thesis surmises results of investigations of the influence of Na, Al and Si inclusion species on the mechanism of Na-LTA thermally induced transformations into carnegieite and nepheline polymorphs. The first chapter of thesis deals with Na-LTA synthesis procedure with different amounts of Na, Al and Si inclusions. The influence of small variations of Na2O:Al2O3:SiO2 ratio in initial reaction mixture on stoichiometry of synthesized Na-LTA zeolites and crystal grain morphology is described. Refluxing treatment at 100 ºC is suggested as method for removing extra-framework species remained after synthesis process, which does not induce amorphization or other structural changes of zeolite. The second chapter of the thesis is focused on the investigation of the influence of Na, Al and Si inclusions on zeolite Na-LTA thermal stability and conversion into carnegieite and nepheline polymorphs. Special attention is dedicated to the investigation of the mechanism of zeolite Na-LTA transformation into low-temperature carnegieite, which is presented with different conversion routes in the literature. In one aspect Na-LTA zeolite transforms directly into low-temperature carnegieite: Na-LTA → low-temperature carnegieite, while in the other, unfolds through amorphous phase: Na- LTA →Amorphous phase → low-temperature carnegieite. XRPD, DTA and IR investigations showed that Na, Al and Si inclusions catalyze zeolite Na-LTA transformation into low-temperature carnegieite, without the possibility of detection of amorphous phase, inducing rapid breaking and formations of bonds, whereby the rate of transformation increases with increasing Al content. On the other hand, in the case of reflux treated Na-LTA zeolite with ideal stoichiometry, thermal transformation into low-temperature carnegieite is preceded by collapse of LTA framework and formation of stable amorphous phase, which subsequently crystallized into low-temperature carnegieite. Characterization of amorphous NaAlSiO4 phase by IR and Raman spectroscopy showed the presence of four- and six-membered tetrahedral rings, which lead to conclusion that by the collapse of zeolite into amorphous phase, relicts of LTA frameworka are retained. This can can be used as a starting point in synthesis of perfect glasses. On higher temperatures, formation conditions of nepheline structures by reconstructive phase transformations of low-temperature carnegieite were investigated. Because of the various nepheline polymorphs with diverse symmetry, formation conditions of different nepheline structures are current problem in mineralogy. Investigation showed that Na, Al and Si inclusion species in Na-LTA zeolite, induce transformation of low-temperature carnegieite into mixture of monoclinic trinepheline and basic hexagonal nepheline, while in the process of thermally induced transformation of reflux treated samples with ideal stoichiometry, pure basic hexagonal nepheline was formed. Also, conditions of thermal conversion of monoclinic trinepheline into basic hexagonal nepheline were investigated. Intermediate phase of nepheline (“ABABAB…”) structure type, which could not be identified according to known nepheline phases, was synthesized in the presence of Na and Si inclusion species. Differences in the short and middle range order between hightemperature NaAlSiO4 polymorphs, formed by thermal conversion of Na-LTA with different stoichiometry, were ascribed to the influence of Na, Al and Si inclusions in zeolite cages.By this investigation we propose that Na-LTA is the example of much wider problem of non-stoichiometry influencing the course of zeolite thermal transformation route and can be extended to other zeolite types containing various extra-framework cations.en
dc.formatapplication/pdf
dc.languagesr
dc.publisherУниверзитет у Београду, Факултет за физичку хемијуsr
dc.relationinfo:eu-repo/grantAgreement/MESTD/Basic Research (BR or ON)/172018/RS//
dc.rightsopenAccessen
dc.sourceУниверзитет у Београдуsr
dc.subjectNa-LTA zeolitsr
dc.subjectNa-LTA zeoliteen
dc.subjectkarnegitsr
dc.subjectnefelinsr
dc.subjecttermalno indukovane fazne transformacijesr
dc.subjectpoliamorfizamsr
dc.subjectrendgenska difraktometrija prahasr
dc.subjectdiferencijalna skenirajuća kalorimetrijasr
dc.subjectskenirajuća elektronska mikroskopijasr
dc.subjectvibraciona spektroskopijasr
dc.subjectNMR spektroskopijasr
dc.subjectcarnegieiteen
dc.subjectnephelineen
dc.subjectthermally induced phase transformationsen
dc.subjectpolyamorphismen
dc.subjectX-ray powder diffractometryen
dc.subjectdifferential scanning calorimetryen
dc.subjectscanning electronic microscopyen
dc.subjectvibrational spectroscopyen
dc.subjectNMR spectroscopyen
dc.titleUticaj inkluzija na fazne transformacije mrežnih alumosilikatasr
dc.titleThe influence of inclusions on phase transformations of framework aluminosilucatesen
dc.typedoctoralThesis
dc.rights.licenseBY-NC-ND
dcterms.abstractДондур, Вера; Вулић, Педраг; Ћирић-Марјановић, Гордана; Дамјановић, Љиљана; Радуловић, Aлександра М.; Утицај инклузија на фазне трансформације мрежних алумосиликата; Утицај инклузија на фазне трансформације мрежних алумосиликата;
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/21071/Disertacija.pdf


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