Crystallization Process Of Glass Research Articles

Wide-Field Polarimetric Second-Harmonic Imaging for Rapid and Nondestructive Investigation of Laser-Induced Crystallization Phenomena.

The selective and controlled formation of nanocrystals in glass is emerging as a versatile method to achieve functional photonics, optoelectronics, and quantum devices, such as single-photon emitters. Here, we investigate the use of wide-field polarimetric second-harmonic (SH) microscopy as a method to rapidly and nondestructively examine nanoscale crystal arrangements in laser-processed glass. As a case study, we investigate tellurite glass, where the formation of a trigonal tellurium (t-Te) nanocrystalline phase after femtosecond laser exposure was recently demonstrated. Combined with theoretical models, we show that wide-field polarimetric SH microscopy offers comprehensive information on the nanocrystals' orientation, distribution, and chirality. With its high imaging throughput and spatial resolution, this method has the potential not only to significantly accelerate investigations on laser-induced glass crystallization processes but also to provide a valuable tool for in situ process monitoring.

Effect of Zn/B molar ratio on the structure, crystallization mechanism and properties of ZnO-B2O3-SiO2 glasses for LTCC applications

ZnO-B2O3-SiO2 glass-ceramics, with the same Si/B molar ratio (0.7) and different Zn/B molar ratios (1.6–2.1) have been prepared by quenching glass melt and heat treatment between 680 °C and 720 °C. DSC analysis has demonstrated that the crystallization activation energy (Ea) of the Zn2SiO4 phase increased with increasing Zn/B ratio, and the glass crystallization process was transformed from a two-dimensional to a one-dimensional growth. DSC curves are consistent with the deformation and viscosity curves and can be attributed to the crystallization behavior of glass. The glass-ceramic with Zn/B = 1.7 sintered at 700 °C for 30 min exhibited the best properties: εr = 6.35; tanδ = 4.3 × 10−3 (11.39 GHz); CTE = 3.8 × 10−6 /K.

Glass-Ceramic Capacitors with Simultaneously High Power and Energy Densities under Practical Charge-Discharge Conditions.

Developing dielectric capacitors with both a high power density and a high energy density for application in power electronics has been a long-standing challenge. Glass-ceramics offer the potential of retaining the high relative permittivity of ceramics and at the same time of exhibiting the high dielectric breakdown strength and fast charge/discharge rate of glasses, thus producing concurrently high power and energy densities in a single material. In this work, glass-ceramics are fabricated to achieve simultaneously high power and energy densities, high efficiency, and thermal stability by tuning the glass crystallization process via a suitable nucleating agent and a high oxygen partial pressure. Under the same practical charge-discharge test conditions, the as-prepared glass-ceramics combine the high energy density of ceramics and ultrafast discharge rate of glasses, producing the highest power density among glass- and ceramic-based dielectric materials. This work demonstrates the significant potential of achieving both high power and energy densities in glass-ceramics by optimizing the glass crystallization process.

Study on Crystallization Process of Li2O-Al2O3-SiO2 Glass-Ceramics Based on In Situ Analysis.

In this paper, we used differential scanning calorimetry (DSC), high-temperature X-ray diffraction (HT-XRD), and confocal scanning laser microscopy (CSLM) to investigate the Li2O-Al2O3-SiO2 glass crystallization process. At 943 K, lithium disilicate (Li2Si2O5) phase crystals began to precipitate in the Li2O-Al2O3-SiO2 glass with a crystal size of 50-70 nm. At the temperature of 1009 K, petalite (LiAlSi4O10) crystals began to precipitate in the vitreous phase, forming composite spherical crystals of LiAlSi4O10 and Li2Si2O5 with size in the range of 90-130 nm. Furthermore, the Kissinger method and KAS method of the JMAK model were used to calculate the crystallization activation energy and the Avrami index "n". It was found that the precipitation mechanism of the two kinds of crystals is whole crystallization; accordingly, the selection of crystallization heat treatment system was guided to determine the nucleation and crystallization temperature.

Ionic Conductivity and Microstructure of Li<sub>4</sub>GeO<sub>4</sub>-Based Solid Electrolytes

Li4GeO4-based solid electrolytes can be synthesized at low temperatures, and their formability is improved by adding Li2SO4. Glass–ceramic Li4GeO4 exhibits a relatively high ionic conductivity of approximately 10−6 S cm−1 at room temperature, which is higher than that of glass Li4GeO4. Thus, Li4GeO4 has promising applications in all-solid-state lithium ion batteries. To understand the correlation between the ionic conductivity, formability, and microstructure of the synthesized materials, the microstructures and crystallization process of glass and glass–ceramic Li4GeO4 and 80Li4GeO4·20Li2SO4 (Li3.6Ge0.8S0.2O4) were observed by transmission electron microscopy (TEM). Since Li3.6Ge0.8S0.2O4 glass exhibits a halo diffraction pattern, the addition of Li2SO4 to Li4GeO4 stabilizes its amorphous phase. In addition, glass–ceramic samples were found to be characterized by an amorphous state containing nanocrystallites with a crystallinity degree of approximately 40%, which improves the ionic conductivity of the material.

Crystallization of Lanthanide-Ho3+ and Tm3+ Ions Doped Tellurite Glasses.

In the presented work, the tellurite glasses TeO2-WO3-ZnO doped with Tm3+ and Ho3+ ions were prepared by the same glass forming method. X-ray diffraction (XRD) and differential thermal analysis (DTA) techniques were used to study the effects of the forming technology on the thermal and structural properties of the fabricated glasses. After controlled crystallization of investigated glasses, the emission in the VIS- and NIR range was determined. The effect of silver doping on emission intensity was investigated. The value of the activation energy of the glass crystallization process was determined, while the Ea value for pure TeO2 glass was much lower than for tellurite glasses TeO2-WO3-ZnO.

Physico-chemical properties and structural transformations in the synthesis of boroalumosilicate glass-crystal materials

The aim of this work is to study the areas of glass formation and metastable liquation of the pseudo-ternary system (MgO·Al2O3)-B2O3-SiO2, and study of the crystallization process of glasses of cordierite composition. The crystallization process of glasses of cordierite composition containing B2O3 by a single-stage heat treatment at 1000 oC and 1200 oC, the nature of crystallization, the thermal properties of glasses and glass crystalline materials of the system (MgO·Al2O3)-B2O3-SiO2 were studied. It revealed that during the isolation of a boron-containing solid solution, the residual glassy phase enriched with oxides of MgO and Al2O3, which lead to an increase in the thermal expansion coefficient of the glass phase. The research results provide possibility to synthesize glass-ceramics with certain thermophysical parameters by stopping further glass crystallization at the stage of formation of a certain amount and ratio of the required crystalline and glassy phases.

In situ observation of Li2O-Al2O3-SiO2 glass crystallization process and kinetics analysis

In this work, we have observed the crystallization process of Li2O-Al2O3-SiO2 glass using a high-temperature confocal laser scanning microscope and studied its crystallization kinetics with differential thermal analysis. The value of activation energy has been calculated out using Kissinger and Flynn–Wall–Ozawa methods. The results show that LiAlSi3O8 crystal particles precipitate at 850 °C, and then gradually grow to 75 um with the irregular hexagonal structure until 980 °C. The activation energy of two exothermal peaks through Kissinger method is 121.78 ± 13.42 and 189.74 ± 7.76 kJ/mol. Glass transition and crystallization both have remarkable kinetics effects, and kinetic crystallization parameter, Avrami index (n), indicates that crystallization mechanism of two exothermal peaks corresponds to one-dimensional and surface crystallization, respectively.

Synthesis and characterization of Na+ conducting glass-ceramic Na5FeSi4O12 doped with boron, aluminum, and gallium oxides

Sodium-ion conductive glass-ceramics of Na5FeSi4O12 were successfully synthesized through the crystallization of glasses with the composition Na5FeSi4O12. The optimum crystallization conditions and the kinetics of the glasses were examined by differential thermal analysis. The characterization of crystallization and conduction properties were performed on thus obtained glass-ceramic Na5FeSi4O12 by a non-isothermal modified Kissinger and complex impedance methods, respectively. The activation energy for crystallization was 279 kJ mol−1 and the sodium-ion conductivity was obtained as 1.33 × 10−3 S cm−1 at 300 °C. To improve the conductivity with a small amount of Si-substitutes, Na5FeSi4O12-isostructural derivatives containing such as B, Al, and Ga were also prepared according to the same crystallization process of glasses with the composition Na5.1FeM0.1Si3.9O12 (M = B, Al, Ga). Without phase separation, the ionic conductivities of glass-ceramics were enhanced up to 1.69 × 10−3 at 300 °C on Na5.1FeB0.1Si3.9O12, whereas decreased down to 1.30 × 10−3 and 1.12 × 10−3 S cm−1 at 300 °C on Na5.1FeAl0.1Si3.9O12, and Na5.1FeGa0.1Si3.9O12, respectively.

Investigation on low-temperature reactive viscous flow sintering behavior of lanthanum-borate glass-ceramic with BaTi4O9 ceramic filler

In this paper, the sintering behavior of the lanthanum-borate (B2O3-La2O3-MgO-TiO2,BLMT) glass-ceramic with BaTi4O9 filler composite was investigated in terms of the wetting behavior, interfacial reaction, sinter-shrinkage process, sintering activation energy, as well as phase and microstructure evolution with change in filler contents and sintering temperature. Our research suggested that the glass is unable to wet the filler material within a temperature up to 1000 °C, indicating that the densification process of composites is dominated by viscous flow of glass matrix. The increase in filler content that performs as a rigid particle in composite causes the rise in the sinter-shrinkage-onset and -end temperature, thereby proving that the viscous-flow densification of the composites with x≤ 30 wt% filler content is accomplished before the crystallization of BLMT glass, whereas the composites with x≥ 40 wt% cannot. After densification, a chemical reaction that almost synchronizes with the glass crystallization occurred between glass and ceramic, which not only imposes significant influence on the crystallization behavior, but eradicates the closed pore formed by the viscous flow and the induced crystallization porosity. The densification process of the BaTi4O9 filler-BLMT glass composite was referred to as two-stage reactive assisted viscous flow sintering process which consists of viscous flow of glass, of the crystallization process of glass, and/or of the chemical reaction between glass and filler.

Transparent Yb3+ doped phosphate glass-ceramics

Yb3+ doped oxyfluorophosphate glasses with the composition (98.75) [90NaPO3-(10-x) Na2O-xNaF] - 1.25Yb2O3 (in mol%) with x = 0, 2.5, 5, 7.5 and 10 were prepared using a standard melting process. The progressive replacement of Na2O by NaF leads to an increase in the number of Q2 units at the expense of the Q1 units. This increase in the polymerization of the glass network leads to a shift of the optical band gap to lower wavelength, to a slight increase in the intensity of the emission at 1000 nm and more importantly to a change in the glass crystallization process. Indeed, both surface and bulk crystallization were observed in the glass with x = 0 while surface crystallization only occurs when NaF is added in the phosphate network. The heat treatment leads to the precipitation of at least three crystalline phases: as x increases, the NaPO3 phase grows at the expense of Na5P3O10. All glasses precipitate the Yb containing crystal, NaYbP2O7 which leads to an increase in the intensity of the emission at 1000 nm compared to the emission at 975 nm. We show for the first time to the best of our knowledge that transparent Yb3+ doped phosphate glass-ceramics can be obtained within this glass system when free of NaF.

The role of glass crystallization processes in preparation of high Li-conductive NASICON-type ceramics

One of the approaches to tackle the problem of limited electrolyte electrochemical stability, which controls the development of novel electrochemical storage devices, is the use of solid electrolytes.

Glass-forming region and optical properties of the TeO2 – ZnO – NiO system

The glass-forming region of the ternary TeO2 – ZnO – NiO system has been determined using a conventional melt-quenching method under controlled condition. The stable samples containing up to 35mol% NiO were prepared by the rapid cooling technique while a low cooling rate was allowed to obtain glasses containing 15mol% NiO. The formation of tellurium, zinc and nickel complex oxides (e.g. NiTe2O5, Zn3Te2O8) crystalline phases in a powder batches during the glass synthesis at different temperatures were studied. Investigations of the crystallization processes in glasses showed the formation of the same complex oxides phases as in the batch. The basic thermal properties of ternary glasses were determined by DSC and an increase of glass temperature with increase in the concentration of NiO in the glass matrix was shown. The optical absorbance spectrum of the glasses exhibited three broad bands with four maxima located at about 430, 720, 810 and 1320nm corresponding to the d-d transitions of Ni2+ ion in octahedral coordination. The ligand field, splitting and Racah parameters were calculated and its dependence on the concentration of NiO was established.

Modification of the Ti40Cu36Zr10Pd14 BMG Crystallization Mechanism with Heating Rates 10-140 K/min

The article presents investigations of Ti40Cu36Zr10Pd14 bulk metallic glass crystallization process heated with the rates of 10, 60, 100 and 140 K/min. High heating rates experiments were performed in a new type of differential scanning calorimeter equipped with a fast responding thermal sensor. Phase composition and microstructure were studied with x-ray diffraction and transmission electron microscopy. The observed crystallization proceeded in two separate steps. Applied high rates of heating/cooling resulted in the crystallization of only one CuTi phase, replacing typical multi-phase crystallization. The microstructure after crystallization was polycrystalline with some amount of amorphous phase retained. Kinetic parameters were determined with the use of the Kissinger and Friedman iso-conversional analysis and Matusita–Sakka iso-kinetic model. The kinetic analysis supplies results concerning autocatalytically activated mechanism of primary crystallization with decreasing activation energy and small density of quenched-in nuclei, in good agreement with previous structural investigations. The mechanism of secondary crystallization required dense nuclei site, increasing activation energy and large nucleation frequency. The amorphous phase of Ti40Cu36Zr10Pd14 BMG revealed high thermal stability against crystallization. Application of high heating rates in DSC experiments might be useful for the determination of mechanism and kinetic parameters in investigations of metallic glasses crystallization, giving reasonable results.

Preparation of PbGeO3 by the oxidation of Pb–Ge melts and its properties

This paper presents experimental data on the oxidation kinetics of a liquid 65 at % Pb + 35 at % Ge alloy in air. Lead metagermanate, PbGeO3, in a glassy state has been prepared by high-temperature oxidation of the melt at 1273 K. Interaction of molten PbGeO3 with crucible materials (SnO2, Au, Pd, and Pt) has been studied by the sessile drop method. Liquid lead germanate has been shown to be highly reactive with substrates from these materials. The heat capacity of the glassy lead metagermanate obtained has been determined by differential scanning calorimetry in the temperature range 300–800 K. In the range 330–630 K, the C p (T) data for glassy PbGeO3 can be represented using the Maier–Kelley equation. Above 630 K, there is a characteristic peak due to glass crystallization processes.

A mathematical model for analysis of sequentially coupled crystallization–melting differential scanning calorimetry peaks and the use of the model for assessing the crystallization resistance of tellurite glasses

Differential scanning calorimetry (DSC) characterization of tellurite glasses doped with lanthanum oxide, which improves their crystallization resistance, has revealed a phase transformation specific to such glasses, in which partial crystallization of a sample is followed by melting of the crystals formed. The experimentally observed dependence of the decrease of crystallization–melting peaks across a series of disperse samples of (TeO2)0.72(WO3)0.24(La2O3)0.04 glass with increasing particle size upon extrapolation to the size of a bulk sample has been used to assess the crystallization resistance of tellurite glasses for optical applications. The assessment technique comprises DSC characterization of particle-size-classified glass samples and the use of a mathematical model for obtaining the degree of crystallization as a function of temperature and time, α(T, t) through analysis of nonisothermal DSC peaks representing a partial glass crystallization process passing into melting. The crystallization resistance of glass is estimated by extrapolating the maximum α values as a function of particle size to a preform size. Tested for (TeO2)0.72(WO3)0.24(La2O3)0.04 glass, the technique offers the possibility of selecting preforms for producing fibers from compositionally new, chemically pure tellurite glasses at a given phase purity level.

Effect of copper introduction into As2Se3 glass matrix on crystallization processes

Crystallization processes in glasses of the Cux(As2Se3)100−x system for x=0, 1, 5, 10 and 15at.% were analyzed by non-isothermal differential scanning calorimetry at different heating rates. Based on the obtained thermograms, the mechanism of incorporation of copper into amorphous As–Se matrix and changes in the structure of the investigated system were analyzed. It was shown that the crystallization process essentially depends on the composition. Depending on the glass composition and the applied heating rate, crystallization of three structural units occurred: As2Se3, CuAsSe2 and Cu2Se. Activation energies of the crystal growth of these structural units were determined. The parameters n and m, numerical factors which depend on the morphology of nucleation and growth, were determined. The analysis of the mechanism of crystallization has shown that the crystallization of As2Se3 is characterized by the value of the Avrami index n=4, which indicates that volume nucleation and three-dimensional growth with variable number of centers of nucleation is involved. Analogous, analysis of the crystallization of structural units Cu2Se and CuAsSe2 has shown that the Avrami index has a value of n=3 (m=3) that corresponds to the volume nucleation and three-dimensional growth, but the number of centers of nucleation does not change.

TNE Effect of Heating Radiation on the Synthesis and Crystallization of Cordierite Composition Glasses

The results on crystallization of glasses of the cordierite composition, synthesized under the influence of concentrated radiant flux of different densities, are presented. Synthesis was carried out using a solar furnace or a solar simulator, wherein Xenon lamps of 10 kW power serve as a heat source. We studied glasses of the following stoichiometric composition 2MgO: 2Al2O3: 5SiO2 without a catalyst and with TiO2 as a catalyst. The initial raw materials were MgO, Al2O3 and quartz-kaolinite-pyrophyllite rock as a main source of SiO2. The natures of phase transitions in the samples obtained are studied using the X-ray analysis (DRON-UM-1) and the differential-thermal method (Derivatograph Q-1500 D). The absorption spectra are obtained on spectrophotometer SF-56. A comparison of the phase composition of the crystallized samples shows that the crystallization of μ-cordierite and the transition of μ-cordierite to α-cordierite in glasses, synthesized using a Xenon lamp, occurs at lower temperatures than those synthesized using solar radiation, provided the same conditions of synthesis and annealing. Besides of this, in glasses containing TiO2, the content of Ti3+ increases, and a decay of the concomitant phase, magnesium-aluminum-titanate, is activated at annealing temperatures above 1200°C. The differences in the character of the phase formation affect the activity of glass powders to sintering. It is found that peculiarities of the spectral composition of a Xenon lamp and the Sun affect the nature of the glass crystallization process. A presence of a significant proportion of extreme ultraviolet radiation initiates the crystallization process by the photo-activation mechanism and has the same effect as a rise of the glass crystallization temperature or an increase of the catalyst concentration.

Crystal formation from glass, crystal structure refinement and thermal behavior of K1−xRbxBSi2O6boroleucite solid solutions from X-ray powder diffraction data

The crystal chemistry of K 1―x Rb x BSi 2 O 6 mixed boroleucites has been studied by means of X-ray powder diffraction at room temperature. Boroleucites under study were prepared by crystallization from glass at 700-1000 °C for a few to 1000 hours time. First glass crystallization process starts from formation of two solid solutions: one of them is related to space group I43d, another to Ia3d. After heat-treatment at 950°C/51 h, K 1―x Rb x BSi 2 O 6 solid solutions crystallize in the cubic space group I43d, in a wide range of compositions as Rietveld refinement of the structures of solid solutions (nominal composition x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) demonstrated. Within a narrow range of x near 0.2 area of immiscibility was found. Under substitution of K by Rb structural parameters (cubic lattice parameter a, (K,Rb)—O bond lengths in (K,Rb)O 15 polyhedron, (K,Rb)-(K,Rb) bond lengths, (K,Rb)―O―(K,Rb) angles between (K,Rb)O 15 polyhedra, and T―O―T angles between tetrahedra) of the phase increased nonlinearly due to cationic size rising. Non-linear behavior of the composition dependence of structural parameters was observed near x = 0.2 ÷ 0.4. A comparative analysis has been made for the K-Rb-Cs substitution in the two sequential boroleucite series KBSi 2 O 6 ―RbBSi 2 O 6 and RbBSi 2 O 6 ―CsBSi 2 O 6 .

The role of strontium and potassium on crystallization and bioactivity of Na 2O–CaO–P 2O 5–SiO 2 glasses

The effect of SrO/CaO and K 2O/Na 2O replacements on the crystallization process of glasses based on Na 2O–CaO–P 2O 5–SiO 2 system was investigated. The glasses were thermally treated through controlled heat treatment regimes to obtain glass ceramic materials. Combeite Na 2Ca 2Si 3O 9, sodium calcium silicate Na 2Ca 3Si 6O 16, wollastonite solid solution, and whitlockite Ca 3(PO 4) 2 were identified as major crystalline phases in the prepared thermally treated glasses. No potassium and strontium-containing phases could be detected in the glass–ceramics; potassium seems to be accommodated in the wollastonite structure, while strontium might be incorporated in the sodium calcium silicate structure. The surface reactivity of the prepared glass–ceramic specimens was also studied in vitro in Kokobo's simulated body fluid (SBF). EDAX, SEM, inductively coupled plasma ICP, and FTIR were used to examine the formation of apatite layer's surface and characterize the glass ceramic surface and SBF compositional changes. A decrease in the bioactivity of the glass ceramic was observed as Na 2O was replaced by K 2O. Strontium together with calcium ions in the apatite layer formed was detected with SrO/CaO replacement. The role played by the glass oxide constituents in determining the crystallization and bioactivity behaviour of the prepared thermally treated glasses was discussed.