o:38593 Sinteza i karakterizacija polifosfatnih stakala sa dodatkom stroncijuma i lantana doktorska disertacija Synthesis and characterization of polyphosphate glasses with addition of strontium and lanthanum : doctoral dissertation sr Predmet rada ove doktorske disertacije bio je dobijanje i karakterizacijapolifosfatnih stakala sa dodatkom stroncijuma i lantana.U ispitivanjima su korišćene metode: atomska apsorpciona spektroskopija (AAS),spektrofotometrija (SF), rendgenska difrakcija (XRD), metoda piknometra(određivanje gustine), infracrvena spektroskopija (FTIR), diferencijalnaskenirajuća kalorimetrija (DSC), skenirajuća elektronska mikroskopija (SEM) itermomikroskopija (HSM).Prva faza istraživanja obuhvatala je sintezu i karakterizaciju četiri fosfatna stakla.Dva stakla su dobijena uvođenjem SrO u sistem, a dva uvođenjem La2O3.Karakterizacija stakala obuhvatala je ispitivanje fizičkih i strukturnihkarakteristika stakala, kristalizacionih karakteristika i sinterabilnosti. Zaodređivanje strukturnih karakteristika stakala- korišćena je metoda infracrvenespektroskopske analize. Kristalizacione karakteristike stakala ispitivane su priizotermskim i neizotermskim uslovima. Vrednosti energija aktivacijekristalizacije, Ea, rastu sa povećanjem količine stroncijuma i lantana u staklima.Ponašanje prahova stakala pri sinterovanju je ispitivano pomoćutermomikroskopa. Dodatkom stroncijum- i lantan-oksida povećava se stabilnoststakla, a relativno visoke vrednosti parametara stabilnosti ukazuju na većuotpornost stakla procesu kristalizacije. Vrednosti energija aktivacije viskoznogtoka, ΔGη, rastu sa povećanjem količine stroncijuma i lantana u staklima.Druga faza istraživanja obuhvatila je sinterovanje prahova fosfatnih stakala iispitivanje uticaja temperature sinterovanja na strukturne karakteristike, faznisastav, poroznost i tvrdoću. Temperature sinterovanja prahova stakala određenesu primenom termomikroskopske i DSC analize. Kristalne faze su identifikovaneXRD analizom termički obrađenih uzoraka. Utvrđeno je prisustvo bioaktivnih fazaβ-CaP2O6, α-Ca3(PO4)2 i β-Ca3(PO4)2. Svi uzorci sinterovani na Tp imaju većuporoznost od uzoraka sinterovanih na Tms, što ukazuje da je ova poroznostuslovljena kristalizacijom. Tvrdoća sinterovanih uzoraka određena je metodom poVikersu i pokazano je da sa porastom poroznosti tvrdoća uzoraka opada.Treća faza istraživanja obuhvatala je analizu hemijske postojanosti uzoraka urastvoru simulirane telesne tečnosti. Masa uzoraka je merena na analitičkoj vagipre i posle eksperimenta, pH vrednost rastvora određivana je pH metrom, akoncentracije elemenata u rastvoru određivane su metodama AAS i SF. Saporastom sadržaja SrO rastvorljivost stakla u SBF-u se povećava, dok se kodstakala sa lantanom rastvorljivost smanjuje sa povećanjem sadržaja La2O3. Uzorcistakala sa stroncijumom sinterovani na Tms i Tp pokazuju slabu rastvorljivost uSBF-u, čak i za najduže eksperimentalno vreme. Najveću rastvorljivost pokazujeuzorak sa nižim sadržajem lantana, sinterovan na Tms.Rezultati ovog istraživanja omogućavaju određivanje uticaja toplotne obrade namikrostrukturu staklo-keramike dobijene kontrolisanom kristalizacijomfosfatnih stakala i uticaj uslova sinterovanja na mikrostrukturu staklo-keramikedobijene sinter-kristalizacijom.Ključne reči: polifosfatno staklo, stroncijum-oksid, lantan-oksid, karakterizacijastakla, sinter-kristalizacija, staklo-keramika, hemijska postojanost The subject of this doctoral dissertation was the preparation and characterizationof polyphosphate glasses with the addition of strontium and lanthanum.The following methods were used in the tests: atomic absorption spectroscopy(AAS), spectrophotometry (SF), X-ray diffraction (XRD), pycnometer method(density determination), infrared spectroscopy (FTIR), differential scanningcalorimetry (DSC), scanning electron microscopy (SEM), and thermomicroscopy(HSM).The first phase of the research included the synthesis and characterization of fourphosphate glasses. Two glasses were obtained by introducing SrO into the system,and two by introducing La2O3. The characterization of the glasses includedexamination of the physical and structural characteristics of the glasses,crystallization characteristics and sinterability. The method of infraredspectroscopic analysis was used to determine the structural characteristics ofglasses. The crystallization characteristics of the glasses were examined underisothermal and non-isothermal conditions. The values of crystallizationactivation energies, Ea, increase with increasing amounts of strontium andlanthanum in the glasses. The behavior of glass powders during sintering wasinvestigated using a thermomicroscope. The addition of strontium and lanthanumoxide increases the stability of the glass, and the relatively high values of thestability parameters indicate a greater resistance of the glass to the crystallizationprocess. The values of the viscous flow activation energies, ΔGη, increase withincreasing amounts of strontium and lanthanum in the glasses.The second phase of the research included sintering of phosphate glass powdersand examination of the influence of sintering temperature on structuralcharacteristics, phase composition, porosity and hardness. The sinteringtemperatures of glass powders were determined using thermomicroscopic andDSC analysis. The crystalline phases were identified by XRD analysis of heattreatedsamples. The presence of bioactive phases β-CaP2O6, α-Ca3(PO4)2 and β-Ca3(PO4)2 was determined. All samples sintered at Tp have higher porosity thansamples sintered at Tms, which indicates that this porosity is due to crystallization.The hardness of the sintered samples was determined by the Vickers method andit was shown that the hardness of the samples decreases with the increase inporosity.The third phase of the research included the analysis of the chemical stability ofthe samples in a simulated body fluid solution. The samples were measured on ananalytical balance before and after the experiment, the pH value of the solutionwas determined with a pH meter, and the concentrations of elements in thesolution were determined by the AAS and SF methods. As the SrO contentincreases, the solubility of the glass in SBF increases, while the solubility of thelanthanum glasses decreases with the increase in the La2O3 content. Samples ofstrontium glasses sintered at Tms and Tp show poor solubility in SBF, even for thelongest experimental time. The highest solubility is shown by the sample withlower lanthanum content, sintered at Tms.The results of this research allow determining the influence of heat treatment onthe microstructure of glass-ceramics obtained by controlled crystallization ofphosphate glasses and the influence of sintering conditions on the microstructureof glass-ceramics obtained by sinter-crystallization. Tehnološko inženjerstvo - Hemijsko inženjerstvo / Technological engineering - Chemical engineering Datum odbrane: 27.09.2024. polifosfatno staklo, stroncijum-oksid, lantan-oksid, karakterizacija stakla, sinter-kristalizacija, staklo-keramika, hemijska postojanost polyphosphate glass, strontium-oxide, lanthanum-oxide, glass characterization, sinter-crystallization, glass-ceramics, chemical stability 91552100 178566409 91552101 10283 2026-04-06T14:40:16.053Z 45 no 46 Vladimir, Topalović 84517129 2024 63 mentor Snežana, 1964- Grujić 12657767 2024 63 mentor Jelena, 1972- Nikolić 7035495 2024 63 član komisije Jelena, 1964- Miladinović 35957863 2024 63 član komisije Rada, 1965- Petrović 12699495 2024 63 član komisije Srđan, 1970- Matijašević 5917031 2024 63 član komisije Jovica, 1974- Stojanović 24060007 2024 63 član komisije Sonja Smiljanić 84520457 2024 122 str. 6784325 http://phaidrabg.bg.ac.rs/o:38593 no yes 12 2026-04-06T14:40:16.320Z 70 11 1067197 1067378 1067403 1738 11A41 2024