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The crystal growth rate of LiGe2(PO4)3 phase from lithium germanium-phosphate glass was studied. The glass have been homogenized using the previously established temperature-time conditions, which make it possible to remove volatile substances from the glass melt. The atomic absorption spectrophotometry (AAS) was used to determine the chemical content of the obtained glass and scanning electron microscope (SEM) were used to reveal the isothermal process of crystal growth. The crystal growth rates were determined experimentally and theoretically.

The crystal growth rate of La(2)SrB(10)O(19)in an undercooled melt of stoichiometric composition was studied. The crystallization of the bulk samples was performed in a single-stage regime under isothermal conditions at the selected temperatures for the different time periods. The surface crystallization was observed and in all crystallized samples, the La(2)SrB(10)O(19)crystalline phase was identified. Based on the dependence of the crystalline layer thickness on treatment time at selected temperature, crystal growth rate was obtained. The crystal growth rates were from 1.65 x 10(-8)to 2.77 x 10(-7)m s(-1)in the temperature interval (700-780 degrees C). The experimental values were compared to the calculated values using theoretical model of the crystal growth. The experimental growth rate followed the same trend as the calculated growth rate, but the experimental values were higher than the calculated.

Due to the dissolution properties the phosphate glasses can be promising materials for the development of new ecologically safe fertilizers. The complex polyphosphate glass with a molar ratio (M2O + MO)/P2O5 gt 1 and addition of microelements Zn2+, Mn2+, Fe3+ and Cu2+ were used in substrate for production of flower and vegetables seedlings. Dissolution tests were conducted in deionized water and 2% citric acid. The effects of the reaction time on the normalized glass mass loss (fm) and the normalized concentrations of the ions (fi) at 20, 30, 37 and 50°C were determined. Dissolution rate constants (kw - deionized water, kc -2% citric acid) were also determined (kw-0.0028-0.0094 gm-2, kc-0.029-0.011 gm-2). Values of kc were higher than those of kw, which confirms a significant effect of solvent type and temperature on the dissolution kinetics of glass. The experiments with plants (one vegetable and one flower) showed that the addition of phosphate glass caused an increase in yield and quality of plants. The applied dose of polyphosphate glass of 1gl-1 showed the best effect on the growth of the examined plant seedlings., Polifosfatno staklo, u kome je molski odnos (M2O + MO)/P2O5 gt 1, koje sadrži i mikroelemente Zn2+, Mn2+, Fe3+ i Cu2+, korišćeno je u supstratu za proizvodnju rasada cveća i povrća. Eksperimenti su izvedeni u stakleniku na Poljoprivrednom fakultetu u Beogradu i u laboratorijama ITNMS. Ispitivano je ponašanje polifosfatnog stakla prilikom rastvaranja u dejonizovanoj vodi i 2% rastvoru limunske kiseline na temperaturama od 20, 30, 37 i 50 °C. Ispitan je uticaj vremena rastvaranja na normalizovani gubitak mase (fm) i normalizovane koncentracije jona (fi). Određene su i konstante brzina rastvaranja(kw-dejonizovana voda, kc -2% rastvor limunske kiseline). Vrednosti kc su veće od vrednosti za kw, što potvrđuje uticaj rastvarača i temperature na proces rastvaranja. Rezultati su pokazali pozitivan efekat polifosfatnog stakla na rast i kvalitet ispitivanih biljaka. Primenjena doza polifosfatnog stakla od 1 gl-1 pokazala je najbolji efekat na rast ispitivanih biljaka-rasada.

The crystal structure of new lanthanum strontium borate glass-ceramics was refined by the Rietveld method. The results showed that La2SrB10O19 has the monoclinic crystal structure, space group C2 (No. 5) with a = 11.1170(6), b = 6.5667(3), c = 9.2363(3) angstrom,beta = 91.481 degrees, V = 674.04(7) angstrom(3), two formula units per unit-cell, and density 3.830 g cm(-3). The main building units of the crystal structure are BO4 tetrahedra and BO3 triangles. Clusters composed of [B5O12] form an infinite double layer running perpendicular to the c-axis. Lanthanum atoms, situated in [B5O12](n) layers, are coordinated with 10 oxygen atom in a form of LaO10 polyhedra, while Sr atoms, located between [B5O12](n) layers, are coordinated with 8 oxygen atoms in a form of SrO8 polyhedra. Microstructural measurements contain both crystallite domain sizes and microstrain calculations obtained by the Warren Averbach and the simplified integral-breadth methods.

Crystallization kinetics of 22.5Li(2)O center dot 10Al(2)O(3)center dot 30GeO(2)center dot 37.5P(2)O(5) (mol%) glass was studied under non-isothermal condition using the differential thermal analysis (DTA). The study was performed by using the first crystallization peak temperature (T-p1) which belongs to the precipitation of LiGe2(PO4)(3) phase in the glass. The activation energy of glass crystallization (E-a) was determined using different isokinetic methods. The dependence of E-a on the degree of glass-crystal transformation (alpha) was studied using model-free isoconversional linear integral KAS (Kissinger-Akahira-Sunose) and FWO (Flynn-Wall-Ozawa) methods. It was shown that the E-a varies with a and hence with temperature and consequently the glass/crystal transformation can be described as a complex process involving different mechanisms of nucleation and growth.

The subject of this doctoral thesis is the study of the crystallization behavior and the sinterability of the borate glasses system La2O3-B2O3-SrO. In literature there are limited data from the crystallization characteristics and sinterability of these glasses. Preliminary goal of this study was to investigate 4 different composition of the system, in which the content lanthanum of was increased at the expense of the strontium, while the boron content remained unchanged: 5,7La2O3·22,9SrO·71,4B2O3; 9,5La2O3·19,1SrO·71,4B2O3; 14,3La2O3·14,3SrO·71,4B2O3 and 19,1La2O3·9,5SrO·71,4B2O3. Physical and the structural properties as well as the crystallization characteristics and sinterability of glasses were investigated. Crystallization behavior was studied by the differentially thermal analysis (DTA), X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM), while the sinterability by the hot stage microscopy (HSM) and DTA. For the identification of the crystalline phases after thermal treatment (after the crystallization) XRD was used. Mechanism of the crystallization and the resulting phase microstructure were observed by SEM. The results of the preliminary investigations revealed that the glass 14,3La2O3·14,3SrO·71,4B2O3 shows the specific crystallization and sinterabilty characteristics. Based on XRD, TEM and SEM results the surface crystallization mechanisam was detected, where the obtained crystalline phase was of the same composition as the initial glass (polymorphic crystallization). In the literature there are no data for this crystalline phase, so XRD and TEM were used for the determination of the unit cell parameters. In order to obtain the best possible sintering results, the glass powder of extremely small particles (nanoparticles) was prepared. The sintering process was followed by the DTA, HSM and the contactless optical dilatometer. The effects of the sintering temperature, as well as the heating rate up to sintering temperatures, Predmet ove doktorske disertacije je ispitvanje kristalizacionog ponašanja i sinterabilnosti boratnih stakala iz sistema La2O3-SrO-B2O3, o čemu postoji ograničen broj podataka u literaturi. Preliminarna ispitivanja su obuhvatala dobijanje 4 različita sastava ovog sistema, tako što se sadržaj lantana povećavao na račun stroncijuma, dok je sadržaj bora bio konstantan: 5,7La2O3·22,9SrO·71,4B2O3; 9,5La2O3·19,1SrO·71,4B2O3; 14,3La2O3·14,3SrO·71,4B2O3 i 19,1La2O3·9,5SrO·71,4B2O3. Isptivana su fizička i strukturna svojstva kao i kristalizacione karakteristike i sinterabilnost. Kristalizaciono ponašanje stakala praćeno je diferencijalnom termijskom analizom (DTA), rendgenskom difrakcijom praha (XRD), transmisionim i skenirajućim elektronskim mikroskopima (TEM i SEM), dok je sinterabilnost prahova praćena primenom termomikroskopa (TM) i DTA. Rendgenskom difrakcijom praha identifikovane su faze nastale tokom toplotne obrade, odnosno nakon kristalizacije, dok je mehanizam kristalizacije, kao i mikrostruktura stakla nakon toplotne obrade ispitivana SEM-om. Rezultati početnih ispitivanja ukazali su da staklo 14,3La2O3·14,3SrO·71,4B2O3 pokazuje niz specifičnosti u pogledu kristalizacionih karakteristika, kao i sinterabilnosti. Na osnovu rezultata XRD, TEM i SEM analize utvrđen je površinski mehanizam rasta kristalne faze koja je istog sastava kao i staklo (polimorfna kristalizacija). Za ovu fazu u literaturi ne postoje podaci, tako da su na osnovu TEM i XRD analize dobijeni podaci za jediničnu ćeliju. U cilju dobijanja što boljih rezultata sinterovanja pripremljen je prah stakla izuzetno malih veličina čestica. Proces sinterovanja, odnosno, sinter-kristalizacije praćen je korišćenjem DTA, TM i optičkog dilatometra. Ispitivan je uticaj temperature sinterovanja, kao i brzine zagrevanja do izabrane temperature sinterovanja na efikasnost sinterovanja. Stepen denzifikacije, uzoraka je određen merenjem poroznosti nakon toplotne obrade. Za identifikaciju faza koje su nastale u sinterova

In this work, the dissolution behavior of a polyphosphate glass, with the composition 45P(2)O(5) center dot 3SiO(2) center dot 25K(2)O center dot 15CaO center dot 10MgO center dot ZnO center dot MnO (mol %), in simulated body fluid (SBF) at a temperature of 37 degrees C for different times was studied. Two powder sizes of the glass (granulation: 0.1-0.3 and 0.3-0.65 mm) and the bulk glass were investigated. The dissolution experiments were conducted under stationary conditions. Changes in the normalized mass release, normalized concentration of ions, pH values, and surface morphology were determined as a function of the dissolution time. The initial rates of glass powder dissolution and leaching of ions, as well as the diffusion coefficient of cations and the releasing rate of ions, during the hydrolysis process of glass were determined. It was shown that the investigated phosphate glass dissolves in SBF incongruently, with neither precipitation nor the formation of newly potentially toxic compounds, in a dissolution period 720 h.

Melt-quenching method was employed for obtaining a glass-ceramic with the following composition 42P(2)O(5). 40CaO.5SrO.10Na(2)O.3TiO(2) (mol%) glass. The crystallization and sintering behavior of glass have been studied by using DTA, HSM, XRD, FTIR and SEM methods. It was determined that the surface and volume crystallization mechanisms act simultaneously in bulk glass samples. The comparison of DTA and HSM data revealed that the sintering and crystallization processes are independent. The sintered calcium phosphate glass ceramic which contained bioactive beta-Ca-3(PO4)(2) and beta-Ca2P2O7 phases was successfully prepared. It was determined that during crystallization the primary phase in the precipitate was beta-Ca(PO3)(2). Other phases appearing in the resulting glass-ceramic were: alpha-Ca2P2O7, gamma-Ca2PO7, Ca4P6O19 and CaHPO4(H2O)(2). Crystalline phases containing Sr and Ti were not detected. SEM analysis of the glass-ceramic microstructure revealed surface crystallization of glass particles and plate-like morphology of crystal growth. The result of the in vitro bioactivity showed that no apatite layer was formed on the surface of the as-prepared glass-ceramic samples after immersion in the simulated body fluid (SBF).

The crystallization and sintering behaviors of polyphosphate glass doped with trace elements Zn and Mn were examined. The heating experiments on bulk and powder glass samples were performed. The parent glass revealed low crystallization ability and the glass crystallization carried out under simultaneous acting of the surface and volume mechanisms. The bulk glass sample isothermally heated at T

The selected lanthanum-strontium borate glasses were prepared by a conventional melt-quenching technique. The compositions of the investigated glasses were chosen to be: 5.7, 9.5, 14.3, 19.1 mol% for La2O3, 22.9, 19.1, 14.3, 9.5 mol% for SrO and 71.4 mol% for B2O3. The density, molar volume, oxygen molar volume, oxygen packing density, oxygen/boron ratios and structural transformations in the glass network were investigated according to the substitution of SrO by La2O3. The density and the molar volume increased in parallel with La2O3 content increase. Simultaneously, oxygen molar volume values increased while the oxygen packing density values decreased. A hot stage microscope (HSM) and a differential thermal analysis (DTA) were used to determine the characteristic temperatures. By increasing the content of lanthanum, the glass transition temperatures, changed with the same trend as the molar volume. Glass stability parameters were calculated from the temperatures obtained by DTA and HSM. The HSM results were used to obtain the viscosity curves by applying the Vogel-Fulcher-Tamman (VFT) equation.

In this study, the crystallization of 30Li(2)O center dot 15Nb(2)O(5)center dot 50SiO(2)center dot 5TiO(2) (mol%) glass was examined. The parent glass was prepared by the standard melt quenching method, and the investigations were performed under non-isothermal and isothermal conditions using the DTA, XRD, SEM and EDS methods. The results revealed primary crystallization of this glass and the dendritic morphology of crystal growth. Three crystalline phases were formed in the glass matrix during crystallization, whereby LiNbO3 was formed as the primary phase, followed by Li2Si2O5 and SiO2 as the secondary. The surface and volume mechanisms of crystallization occur. The condition that both the mechanisms were dominant was determined. In the case of volume crystallization, the characteristics of the nucleation process were examined. The kinetic parameters of crystallization under different mechanisms of crystallization were determined.

Glasses with a constant B2O3 and an increasing La2O3 content in the system La2O3-SrO-B2O3 were obtained by the usual melt quenching procedure. The crystallization and sinterability of the glasses were investigated by hot stage microscopy (HSM), differential thermal analysis (DTA), X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). XRD analysis of the bulk samples evidenced the formation of the crystalline phases: La2SrB10O19, SrB6O10 and SrLaBO4. XRD and TEM/SAED analyses showed a polymorphic crystallization of the glass sample containing 14.3 mol% La2O3 with precipitation of the La2SrB10O19 phase. SEM analysis confirmed the surface crystallization mechanism of this sample. The kinetics of crystallization of the same sample was examined by DTA and the activation energy of crystal growth was calculated by the Kissinger model to be E-a=458 +/- 63 kJ mol(-1).

The dissolution behavior of a polyphosphate glass with a molar ratio [M2O + MO]/P2O5 gt 1 in distilled water under static condition was studied. The leaching tests were performed with glass powder samples (0.1-0.65 mm) at T=15-50 degrees C for times up to 720 h. The mass loss of the samples, the changes of pH and the concentration of elements (P, K, Ca, Mg, Zn and Mn) in solution were determined. The effects of temperature, time and particle size were analyzed. The results of the tests showed a complex dissolution behavior of this glass. The selective dissolution of the glass components was determined. The mechanism of formation and the structure of dissolved glass layer were investigated. The effects of cations on the mechanisms and kinetics of dissolution of the polyphosphate glass are presented. The activation energy of dissolution, Ea, was determined to be 39 +/- 5 kJ/mol.

The results of preparation and structural characterization of glass-ceramics from the system Li2O-Al2O3-GeO2-P2O5 are shown in this paper. The crystallization behaviour of the selected glass was examined under non-isothermal and isothermal crystallization conditions. DTA, XRD and SEM methods were employed for analyses. It was confirmed that this glass crystallizes by the volume crystallization mechanism. The results also showed that the glass crystallize by primary crystallization. As a primary phase the LiGe2(PO4)3 is formed and the traces of GeO2 as a secondary one is present. The crystallization process occurred at a high homogeneous nucleation rate and the spherical morphology of crystal growth. By applying the Kissinger relation the activation energy of crystal growth Ea = 462 kJ/mol was determined.

Predmet ove doktorske disertacije je ispitivanje kristalizacionog ponašanja germanatnih i germanatnofosfatnih stakala iz sistema K2O-Nb2O5-GeO2 i Li2O-Al2O3- GeO2-P2O5. Na osnovu preliminarnih ispitivanja za proučavanje su izabrana stakla sastava: 30K2O·34Nb2O5·36GeO2 (mol%) i 22,5Li2O·10Al2O3·30GeO2·37,5P2O5 (mol%). Kristalizacione osobine ispitane su pri izotermskim i neizotermskim uslovima kristalizacije. Dobijeni rezultati pokazuju da trokomponentno germanatno staklo kristališe primarnom kristalizacijom, pri čemu fazni sastav kristalisanog uzorka kao i nastajanje pojedinih kristalnih faza zavise od temperature kristalizacije. Na temperaturama kristalizacije < 800 °C kao primarna faza javlja se K3.8Nb5Ge3O20.4, a kao sekundarne faze javljaju se K4Nb6O17 i K6Nb6Ge4O26. Na temperaturama kristalizacije > 800 °C kao primarna faza javlja se K6Nb6Ge4O26, a kao sekundarne faze javljaju se: K3.8Nb5Ge3O20.4, K10Nb22Ge4O68 i KNbO3 faza. Dimenzije kristalita su 20-100 nm. U slučaju četvorokomponentnog germanatnofosfatnog stakla utvrñena je primarna kristalizacija LiGe2[PO4]3 faze sa dimenzijama kristalita 30-500 nm. Odreñen je uticaj granulacije praha stakla na mehanizam kristalizacije i fazni sastav kristalisanih uzoraka. U slučaju kompaktnih uzoraka stakla konstatovan je zapremiski mehanizam kristalizacije sa sferulitskom morfologijom rasta kristala kod oba sastava. Ispitan je proces nukleacije i odreñena je temperaturna i vremenska zavisnost brzine nukleacije. Brzine nukleacije ovih stakala su u oblasti 1,77·1014 - 7,34·1016 m-3s-1 . Odreñena je temperaturna zavisnost brzina rasta kristala i energije aktivacije koje iznose od 294 kJ/mol do 1150 kJ/mol u zavisnosti od faze koja se formira. Odreñene su oblasti nukleacije i rasta kristala, temperature maksimalne brzine nukleacije i procenjene temperature maksimalne brzine rasta kristala. Konstatovano je preklapanje oblasti nukleacije i rasta kristala kod oba sastava. U ispitivanjima su korišćene metode atomske apsorpcione (, The subject of this thesis is the study of the crystallization behavior of germanate and germano-phosphate glasses from the systems K2O-Nb2O5-GeO2 and Li2O-Al2O3-GeO2- P2O5. Based on preliminary experiments the glasses of composition 30K2O·34Nb2O5·36GeO2 (mol%) and 22,5Li2O·10Al2O3·30GeO2·37,5P2O5 (mol%) were selected for examination. The crystallization properties were examined under isothermal and non-isothermal crystallization conditions. Three-component germanate glass crystallize by primary crystallization while the phase composition of crystallized sample and formation of the crystalline phases depends on temperature of crystallization. At crystallization temperatures < 800°C as the primary phase K3.8Nb5Ge3O20.4, appeared and as seconday ones are K4Nb6O17 and K6Nb6Ge4O26. For T > 800 °C, the K6Nb6Ge4O26 appeared as primary phase and as secondary ones are K3.8Nb5Ge3O20.4, K10Nb22Ge4O68 and KNbO3. In the case of four-component germano-phosphate glass the primary crystallization of LiGe2[PO4]3 phase with crystallites dimension of 30-500 nm was detected. The effect of the grain size of glass powders on crystallization mechanism and phase composition of the crystallized samples was determined. For both glass compositions the volume crystallization mechanism with a spherulitic growth morphology of crystals was determined on compact glass samples. The nucleation process was studied and the temperature and time dependencies of nucleation rate were defined. The nucleation rate of these glasses are in the range 1,77·1014 - 7,34×1016 m-3s-1 . Also, the temperature dependence of crystal growth rate was determined and the activation energies calculated are 294 - 1150 kJ/mol depending on the phase formed. The temperature ranges of nucleation and crystal growth and the temperature of maximal nucleation rate and the temperatures of maximal crystal growth rates were determined. For both glass compositions, an overlapping of nucleation and crystal growth range was noted. The me

This paper investigates the possibility and justification of controlled release glass application as a new ecological material in the production of plants-seedlings of French marigold (Tagetes patula L.). During the investigation its influence on the development of the produced plants-seedlings was monitored. The seedlings were produced in poly-propylene containers (speedling system) and poly-propylene pots (pot system). The trial was conducted in the greenhouse at the Faculty of Agriculture in Belgrade during 2011. In the course of seedling production the glass granulation of lt 0.5 mm was added in the following doses: 0, 1, 2, 3, and 4 g/l. The results of the research show a positive effect of controlled release glass application in the production of French marigold seedlings, since high quality seedlings were produced justifying its application. The best effect on the analyzed parameters of plant-seedling development was found when substrate was applied in the dose of 1 g/l., U radu je ispitivana mogućnost i opravdanost primene stakla sa kontrolisanim otpuštanjem hranljivih elemenata kao novog ekološkog materijala u proizvodnji biljaka-rasada kadifice (Tagetes patula L.). Tokom istraživanja praćen je njegov uticaj na razvijenost proizvedenih biljaka-rasada. Biljke-rasada proizvedene su u polistirenskim kontejnerima (speedling system) i polipropilenskim saksijama (pot system). Istraživanja su sprovedena u stakleniku Poljoprivrednog fakulteta u Beogradu tokom 2011. U toku proizvodnje rasada dodavano je ispitivano staklo granulacije lt 0,5 mm u dozama 0-4 g/l. Rezultati istraživanja ukazuju na pozitivan efekat primenjenog stakla sa kontrolisanim otpuštanjem jona u proizvodnji biljaka-rasada kadifice. Njegovom primenom dobija se rasad bolje razvijenosti, te je njegova upotreba opravdana. Najbolji efekat na ispitivane parametre razvijenosti biljaka-rasada imala je doza od 1 g/l supstrata.

In this paper the new methods for reduction of NOx emission from glass melting furnaces were presented. The secondary measures are focused on development of different methods for elimination of nitrogen oxide from the smoke gasses. The main characteristics of the selective catalytic reduction process (SCR), selective non catalytic reduction process (SNCR) and 3R process were presented and some advantages and limitations of these processes were analyzed., U ovom radu su prikazani novi postupci smanjenja emisije NOx iz peći za topljenje stakla. Zbog visokih temperatura do kojih se zagreva vazduh neophodan za sagorevanje dolazi do visoke emisije oksida NOx iz staklarskih peći. Sekundarne mere usmerene su na razvoj postupaka za uklanjanje azotnih oksida iz dimnih gasova. Dat je prikaz selektivno nekatalitičkog, selektivno katalitičkog redukcionog i 3R postupka kao i njihove prednosti i nedostaci.

This paper deals with the crystallization of glass 30Li2O·15Nb2O5·50SiO2·5TiO2 (mol%). The crystallization behavior was studied under isothermal and non-isothermal conditions. XRD and SEM methods were employed for determination of phase composition and microstructure of crystallized glass. It was detected that this glass crystallizes by the surface crystallization mechanism. SEM micrographs of the crystallized samples revealed that the crystals grow in the form of dendrites. The glass-ceramics with complex phase composition was obtained. Three crystalline phases were detected where LiNbO3 has grown as primary phase and a secondary ones Li2Si2O5 and SiO2 appeared. The calculated average crystallite sizes are: 27 nm for LiNbO3 , 115 nm for Li2Si2O5 and 45 nm for SiO2 . From the experimental data an activation energy of crystals growth, calculated using the Kissinger relation, is Ea = 275 ±10 KJ / mol.