Glass-ceramic Samples Research Articles

Morphological, optical, structural, mechanical, and radiation-shielding properties of borosilicate glass–ceramic system

This study explores the morphological, optical, structural, mechanical, and radiation-shielding properties of borosilicate glass–ceramic samples modified with titanium oxide and various ratios of barium oxide. The morphology of the glass–ceramic system was investigated using scanning electron microscopy (SEM). The mechanical properties, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) were used to identify the fabricated sample structures. The optical properties were calculated to define the refractive index and band gap (Eg). The shielding properties were obtained by Monte Carlo simulation (MC) and compared with XCOM software data. Glass samples were converted to glass–ceramic samples at 800 °C for 6 h, and the GC25 and GC30 samples were converted to completely crystalline phases as illustrated by the XRD, FTIR, and Raman results, unlike the GC15 and GC20 samples. The XRD results showed the trigonal structure of BaB2TiO6 with the R-3 space group for the GC25 and GC30 samples and the tetragonal phase of TiO2 with the P42/mnm space group for the GC15 and GC20 samples. The sharp FTIR and Raman spectrum peaks affirm the crystal phase for G25 and G30 samples. The parent glass of the GC20 sample showed the highest mechanical moduli (Young's, bulk, shear, and longitudinal) and Poisson ratio. Concurrently, the addition of BaO instead of B2O3 caused a gradual reduction in the packing factor, dissociation energy, and microhardness. The Phy-X program was used to theoretically assess the shielding properties. The obtained results showed the highest compatibility between the Monte Carlo N-particle (MCNP) and XCOM software results, and the GC30 sample displayed the highest shielding properties due to adding BaO instead of B2O3. The crystalline phase and shielding features of the samples were improved by increasing the BaO ratio, indicating that the current samples are suitable for radiation-shielding applications.

Original KGd2F7 nanocrystals in fluoro-oxide glass ceramics by Dy3+/Sm3+ co-doped for white light emission

Serial fluoro-oxide glass ceramics (GCs) containing 0.6 mol% Dy 3+ and various Sm 3+ from 0 mol% to 1.5 mol% co-doped novel KGd 2 F 7 nanocrystals were firstly fabricated through high temperature melt-quenching method. Then the microscopic structure of the GCs was revealed by transmission electron microscopy (TEM). And the rare-earth ions (RE 3+ ) of Dy 3+ and Sm 3+ were successfully doped in monoclinic-phase KGd 2 F 7 nanocrystals, which can be verified by energy-dispersive X-ray spectroscopy (EDX) mappings. The photoluminescence spectra of the GCs were probed systematically utilizing 365 nm excitation light. The yellow (573 nm), green (486 nm), and red (648 nm) multiple emissions were observed in the co-doped GCs, and the intensity of red became stronger because of the higher Sm 3+ doping concentrations. This contribution of multiple emissions is due to the co-absorption of both Dy 3+ and Sm 3+ for 365 nm and the presence of energy transfer (ET). Moreover, the ET between Dy 3+ and Sm 3+ was confirmed from the variations of emission spectra and measured decay curves of emissions. Furthermore, the maximum energy transfer efficiency (ETE) from Dy 3+ to Sm 3+ can reach ~60.34% and the internal quantum yield (QY) is computed to be around 31.82% upon excitation of 365 nm. The chromaticity coordinates (CIE (Commission Internationale de L′Eclairage)− 1931) of the GCs can be tuned effectively through changing activator concentrations. Ideal white light emission is at the CIE (0.3357, 0.3342), which was achieved for 0.6 mol% Dy 3+ /0.9 mol% Sm 3+ doped GCs sample. The results indicated that Dy 3+ /Sm 3+ co-doped GCs with both high thermal and chemical-physical stabilities have strong potential application in white light-emitting diodes and fluorescent display devices. • The Dy 3+ /Sm 3+ co-doped fluoro-oxide glass ceramics containing novel KGd 2 F 7 nanocrystals were firstly fabricated. • The Dy 3+ and Sm 3+ ions were successfully doped in monoclinic-phase KGd 2 F 7 nanocrystals. • The standard white light emission was obtained by changing the concentration of Sm 3+ . • The energy transfer process from the Dy 3+ to Sm 3+ has been verified to dipole-dipole interaction mechanism. • The fluoro-oxide glass ceramics containing KGd 2 F 7 nanocrystals exhibit high thermal stability.

The effect of borate bioactive glass ceramics containing silver nanoparticles on removal physiognomies of methylene blue

Several studies have been carried out with several materials on the removal of methylene blue from water. Well-known bioactive glass 46S5.2 was prepared by complete replacement of the silicate partner with boron oxide via a two-step crystallization process, in particular its glass-ceramic derivative. The characterization techniques for ceramic sample were performed such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX). Transmission electron microscope (TEM) was employed to ensure that silver addition reaches to the nanoscale. UV/Vis. optical absorption spectroscopy was utilized in the retracing process of methylene blue adsorption from its contaminated water. The antimicrobial activity of the prepared sample was also studied extensively. Also for the prepared glass-ceramic samples, the reusability test was carried out to ensure that they could be used more than once in water treatment applications.

Glass-Ceramics from Trachyte Rock- Limestone or Magnesite

Inexpensive sintered glass-ceramic glaze was prepared from a mixture of Egyptian trachyte with either limestone or magnesite. A represented trachyte rock was pulverized to powder (<0.083 mm) and also both limestone and magnesite. The well mixed batches were melted near 1450 °C/3 h temperature then the glass melt was quenched in water, dried, pulverized to powder and finally shaped in moulds. The sintering process of the pre-shaped glasses, within 1000-1100 °C range, gave augite and olivine in case of trachyte-magnesite whereas wollastonite and Ca-olivine in case of trachyte-limestone. However, cristobalite was developed in both cases. The microstructures in both cases showed glassy matrix scattered with submicron and nano-size crystals either in irregular shape in case of trachyte-limestone or clear crystals in case of trachyte-magnesite. The densities of the sintered samples were in the range of 2.36 and 2.57 g/cm3 in case of the trachyte-limestone and 2.36 and 2.64 g/cm3 in case of the trachyte-magnesite. The coefficient of thermal expansion (CTE) and the hardness of the sintered glass-ceramic were in the range of 6.2-8.5 × 10−6 °C−1 and 440-563 GPa respectively. However, the CTE values decreased in case of trachyte-limestone whereas the hardness values were high in case of trachyte-magnesite. The present glass-ceramic samples had porcelain nature and could be used in cladding of wall and floor.

Crystallization temperature dependence of structure, electrical and energy storage properties in BaO–Na2O–Nb2O5–Al2O3–B2O3 glass ceramics

For dielectric capacitors, high energy density and discharge power density are crucial for utilisation in pulsed power devices. In this paper, BaO–Na2O–Nb2O5–Al2O3–B2O3 (BNN-AB) glass ceramics were successfully fabricated by melt quenching and heat treatment techniques. With increasing crystallization temperature, both the dielectric permittivity and breakdown strength (BDS) first increased and then decreased. When the crystallization temperature was lower than 800 °C, the principal crystalline phase was Ba2NaNb5O15 and the secondary phase was NaNbO3. When crystallization temperature was increased from 800 °C to 830 °C, a small amount of a third phase (Al4B2O9) appeared. At the crystallization temperature of 770 °C, the compact glass ceramics with a fine grain structure had the highest permittivity (∼216 @ 25 °C) and high BDS (∼1170 kV/cm). A single-layer capacitor made of glass ceramics had a high power density (∼414 MW/cm3) and discharge energy density (∼1.93 J/cm3), measured by the charge-discharge test platform under the applied field strength of 500 kV/cm. The discharge energy density of glass ceramics sample was as much as 7.7 times that of the mother glass. The above evidences indicate that BNN-AB glass ceramic materials have broad application prospects in the field of dielectric energy storage.

Novel transparent Tb3+-activated Na2GdF7 glass ceramics for low-lying state thermal coupling principle

Oxy-fluoride glass ceramics (GC), which are composed of glass phase and equally distributed fluoride nano-crystals, are regarded as promising host materials employed to optical thermometer. Herein, novel Na2GdF7:xTb3+ (x = 0.02, 0.03, 0.04, 0.05, and 0.06) GC with high transparency were well fabricated and applied to low-lying state thermal coupling principle. The structural, micro-topography and fluorescence spectra properties of these samples were completely researched via XRD, TEM, HRTEM, SAED and photoluminescence. When excited by 378 nm laser, the luminescence of Na2GdF7:0.3Tb3+ GC was increased 1.5 times compared with precursor glass. More importantly, the Na2GdF7:0.3Tb3+ GC sample (λex = 541.8 nm) was devoted to low-lying state thermal coupling principle. The strategy endows excellent relative sensitivity and superior temperature resolution which are 2.33% K−1 at 310 K and 0.06 K at 670 K, respectively. These findings suggest potential optical materials and a strategy for optical fiber temperature sensing.

Investigation into the viability of the properties of porous glass-ceramics produced from granite dust and maize cob for use in thermal insulation of external walls of residential buildings

Given the enormous need for cost-effective wall insulation materials in the developing countries and Nigeria specifically, this study, explores the viability of porous glass-ceramics production from granite dust and maize cob using one-step sintering technology. The chemical compositions of the locally sourced materials used including granite dust, ball clay and maize cob were obtained using XRF. 300µm of granite dust and ball clay as well as 425µm of maize cob powder were used. Different amount of granite dust and maize cob powder were mixed with constant amount of a mixture of NaOH and Na2SiO3 in three different groupings to formulate the porous glass-ceramics samples. The formulated samples were uniaxially pressed at 10MPa and sintered in a gas kiln at 850oC for 3 hours. The sintered samples were subjected to experimental tests. The results showed water absorption, apparent porosity, bulk density, compressive strength and thermal conductivity of 25.6%–46.7%, 43.5%–75%, 1.45g/cm3 –1.9g/cm3, 0.7MPa–9.7MPa and 0.11W/m.K–0.53W/m.K respectively. The mineralogical properties of the sintered samples were obtained using XRD. The results indicated a viable material for use in thermal insulation of residential buildings.

Development of cordierite-based glass-ceramics by slip casting through selecting the appropriate sintering conditions

The present work aims to prepare a dense cordierite-based glass-ceramic through slip casting and consequent heat treatment procedures. In this regard, sintering conditions were considered as the key variables to improve the properties of the glass-ceramic. For this purpose, glass frit powder was prepared through melting oxide powders (in the system of SiO2-Al2O3-TiO2-K2O-CaO-MgO). The mixed powders were then heat treated at 1450 °C for 1 hour and quenched in water. The glass frit powder was slip cast using the appropriate dispersant. Sintering was carried out by one-step, two-step, and three-step procedures. Specimens were characterized in terms of various analysis techniques including dilatometry, X-ray diffractometry, scanning electron microscopy, and mechanical strength measurement. Among the examined specimens, the sample sintered by a three-step approach was considered the optimized one which attained zero porosity. According to the obtained results, cordierite crystals were observable in this glass-ceramic matrix. A low coefficient of thermal expansion and a low dielectric constant were observed for the optimized glass-ceramic sample. The obtained results confirmed that the homogenous distributions of crystalline phases are responsible for the appropriate and desirable properties of the prepared glass-ceramic.

Microstructure, cytocompatibility, and chemical durability of chemically strengthened LAS (Li2O-Al2O3-SiO2) glass-ceramic materials

The K+-Na+ ion exchange was used to strengthen LAS glass-ceramic materials prepared by hot-pressing sintering. The microstructure, cytocompatibility, and chemical durability of the chemically strengthened LAS glass-ceramics were characterized. The XRD results showed that the K+-Na+ ion exchange mainly occurred between the glass phase of the LAS glass-ceramics and molten salt baths. The ion-exchange process was mainly responsible for the improved chemical durability of the LAS glass-ceramics. The dissolution in acetic acid was significantly reduced from 72 to 15 μg·cm−2 after the ion-exchange treatment, which was attributed to residual compressive stress and increased contents of Q3 and Q4 structural units in the surface region of the LAS glass-ceramics. In addition, the chemically strengthened LAS glass-ceramic samples exhibited good biocompatibility determined by the CCK-8 process using the L929 cell line, having a promising potential as dental restorative materials.

Effect of Er:YAG laser pretreatment on glass-ceramic surface in vitro.

This study investigated the feasibility of using an Er:YAG laser to pretreat glass-ceramic surface and evaluate the effect of the treatment on the bonding strength and marginal adaptation between glass-ceramic and dentin. Glass-ceramic samples (CEREC Blocs) and third molars were cut into 6mm × 6mm × 2mm plates. Thirty ceramic plates were randomly divided into 5 groups: group A (control), group B (pretreated with 9.6% hydrofluoric acid [HF]), group C (pretreated with the Er:YAG laser at 300mJ and 15Hz), group D (pretreated with the Er:YAG laser at 400mJ and 15Hz), and group E (pretreated with the Er:YAG laser at 500mJ and 15Hz). The surface morphologies of the samples in each group were studied under a scanning electron microscope, and the sample displaying optimal etching parameters was selected for subsequent experiments. Based on the surface treatments, 30 ceramic and dentin plates were randomly allocated into 3 groups: the control, laser, and acid-etching groups. After bonding a ceramic plate to a dentin plate, the microleakage and bonding strength were measured, and the pretreatment effects of the Er:YAG laser and 9.6% HF were compared. Group E exhibited an etching effect that was more pronounced and uniform than that in groups C and D. Microleakage and bonding strength analyses revealed that the laser and acid-etching groups differed significantly from the control group in dye penetration depth and shear strength (P < 0.05), although the laser and acid-etching groups did not differ from each other. Both 9.6% hydrofluoric acid and Er:YAG laser pretreatments can coarsen glass-ceramic surfaces, improve the marginal adaptation and bonding strength between the glass-ceramic and dentin, and decrease microleakage of the materials. The two treatments showed no apparent differences in pretreatment outcomes.

Influence of combining Al2O3, La2O3, Gd2O3, and Dy2O3 with barium borosilicate glass-ceramics: a case study of gamma radiation interaction parameters

The goal of this investigation is to test the barium boro-silicate glass-ceramics with different additives against gamma radiation using the FLUKA Monte Carlo code. On four different glass-ceramics samples, the effect of an equal quantity of Al2O3, La2O3, Gd2O3, and Dy2O3 with barium borosilicate glass-ceramics on the radiation shielding capabilities of the glass-ceramics was investigated. In the examined glass ceramics, densities were obtained to investigate glass samples. The densities obtained were 3.92, 4.432, 4.52, and 4.88 g/cm3, respectively. BBSDy sample has the highest density which indicates that it is more effective for radiation shielding. The shielding parameters have been calculated at 0.356, 0.662, 1.173, and 1.333 MeV. The obtained results have been compared with the NistXCOM web page and Phy-X/PSD platform. The results showed a good agreement between FLUKA code, NistXCOM, and Phy-X/PSD. The calculated shielding parameters increase with additive (Al2O3, La2O3, Gd2O3, and Dy2O3). Moreover, the 50BaO–15SiO2–30B2O3–5Al2O3-5Dy2O3 specimen has the best radiation shielding features among the other glass-ceramics. In conclusion, the BBSDY sample containing 5 mol per cent 5 mol% Dy–III–Oxide would be the most effective in terms of radiation shielding, based on the results obtained in this study. When Dy-III Oxide concentrations were increased, linear and mass attenuation coefficient values were significantly increased, which contributed directly to the development of radiation shielding characteristics in the glass-ceramic.

Mechanical properties and machinability of lithium silicate glass-ceramics with varying MgO content

This study focused on the role of lithium metasilicate crystalline phase and microstructural evolution on altering the mechanical properties and machinability of two glass-ceramic system, (Li2O–K2O–Na2O–CaO–MgO–ZrO2–Al2O3–P2O5–SiO2), previously developed by our research group. Our previous study showed that increasing MgO content introduced phase separation and thus controlling the crystallization and microstructure of the glass-ceramics. For this study we chose the glass ceramic system with 1.5 and 4.5 mol% MgO. The glass-ceramics were prepared by melt cast method followed by heat treatment at 650 °C to induce partial crystallization. The crystalline phase in the glass-ceramics was identified by x-ray diffraction and the quantification of crystalline and amorphous phase content was done using Rietveld refinement. The hardness and elastic moduli were measured by nanoindentation. Vickers hardness and fracture toughness were determined by micro indentation. Nano scratch test was performed and scratch morphology was characterized using AFM and FEG-SEM. In order to compare the machinability of the prepared glass-ceramic samples, milling experiments were carried out using CNC milling machine, and machining characteristics were compared by analysing machining force, surface roughness and microstructure of the machined surface. Presence of higher amount of lithium metasilicate (LS) crystals in higher magnesia containing glass-ceramic (G2) resulted in lower average force (Fyrms) as compared to lower MgO containing glass-ceramic. However, due to a wide range of variation in crystal size (150 nm - 2 μm) in higher MgO containing glass-ceramic, the force fluctuation was more than lower MgO containing glass-ceramics.

Synthesise and Characterization of Cordierite and Wollastonite Glass-Ceramics Derived from Industrial Wastes and Natural Raw Materials.

Industrial waste is one of the primary sources that harm the environment, and this topic has occupied many scientists on how to take advantage of these wastes or dispose of them and create a clean environment. By-pass cement dust is considered one of the most dangerous industrial wastes due to its fine granular size and its volatilization in the air, which causes severe environmental damage to human and animal health, and this is the reason for choosing the current research point. In this article, eight samples of glass–ceramics were prepared using by-pass cement dust and natural raw materials known as silica sand, magnesite, and kaolin. Then melted by using an electric furnace which was adjusted at a range of temperatures from 1550 to 1600 °C for 2 to 3 h; the samples were cast and were subjected to heat treatment at 1000 °C for 2 h based on the DTA results in order to produce crystalline materials. Various techniques were used to study the synthesized glass–ceramic samples, including differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscope (SEM), and thermal expansion coefficient (CTE). X-ray analysis showed that the phases formed through investigated glass–ceramic samples consisted mainly of β- wollastonite, parawollastonite, diopside, anorthite, and cordierite. It was noticed that β- the wollastonite phase was formed first and then turned into parawollastonite, and also, the anorthite mineral was formed at low temperatures before the formation of the diopside mineral. SEM showed that the formed microstructure turned from a coarse grain texture to a fine-grained texture, by increasing the percentage of cordierite. It also showed that the increase in time at the endothermic temperature significantly affected the crystalline texture by giving a fine-grained crystalline texture. The linear thermal expansion measurements technique used for the studied glass–ceramic samples gives thermal expansion coefficients ranging from 6.2161 × 10−6 to 2.6181 × 10−6 C−1 (in the range of 20–700 °C), and it decreased by increasing cordierite percent.

Influence of graphene nanopowder impurities on the structural and optical properties of sodium borate copper-based glass: Towards UV/NIR shielding materials

Graphene nanopowder was used as an unconventional additive to the studied oxide glasses, where it was added to the raw components of the copper-sodium borate glass by weight% according to the chemical formula :[(B2O3)0.6mol%(Na2O)0.3mol%(Cu2O3)0.2mol%]+(Graphene)x, where x = 0, 0.2, 0.4, 0.6 and 1 g. Then, the traditional melt quenching method was considered for the glass preparation process. X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Ultraviolet–Visible spectra UV–Vis, and the electron spin resonance (ESR) were used for the characterization processes. According to the XRD patterns, the prepared samples have been divided into two categories, pure glassy samples (x < 0.6 g), and glass-ceramic samples (x ≥ 0.6 g). The FTIR showed the presence of the structural groups BO3 and BO4 as well CO. Also, FTIR showed a conversion from BO3 to BO4 when the content of graphene increased, which means a decrease in the number of nonbridging oxygen atoms NBOs. The deconvolution parameters showed an increase in the relative area of the band assigned to the OH and CH2 groups. According to ESR spectral analysis, Cu2+ ions should occupy octahedral sites with tetragonal distortion as the ground state, where the effective g values and the peak-to-peak width were computed and linked with the structural variation of the prepared samples. The UV–Vis optical measurements showed that the as-prepared glasses/glass-ceramics could act as an optical pass filter in the region of the visible light, as well as good candidates for UV- and NIR shielding applications.

Synthesis and Characterization of Bismuth Borate-Barium Titanate Glass Ceramics

Objectives: In the present investigation, transparent novel glass embedded with ferroic matrix was prepared by melt-quenching method. Among all the glasses, selective glass ceramic is also prepared. Optical and electrical measurements were carried out on the samples. Methods: We have prepared the transparent glass composition of (100-x)[0.55Bi2O3-0.30B2O3-0.15TiO2] +xBaTiO3 ; with x=0, 10, 20, 30, 40, 50 wt.%. Appropriate amounts of reactant mixture were well mixed in agate mortar and melted in a porcelain crucible. The composition is quickly quenched by pouring on pre-heated stainless-steel plate and pressed with another plate. Differential Thermal Analysis was made on the glasses. Detailed optical absorption and impedance measurements were made on the said above glass matrix. Findings: From the XRD spectra, amorphous and crystalline nature was established on the glass and glass ceramic sample. Optical absorption spectra show that with increasing the BaTiO3 in the glass matrix, it results into structural compactness by means of non-bridging oxygen. The results are consistent with the oxygen packing density values. Impedance spectroscopic plots have shown broad peaks and therefore these materials are being considered as special type multicomponent glass ceramics. Disorder nature of the samples was also discussed with the help of dc-conductivity plots. Among all the samples, 60-BBT-40BT has shown broad spectroscopic peak. Therefore, this sample was annealed at 700oC, and the XRD pattern resembles with Bi4Ti3O12 Aurivillius phase, instead of BaTiO3 phase. Detailed impedance measurements were also made on the glass ceramic. Novelty: Dielectric ceramic-glass are being used to fabricate energy storage capacitors; however, further studies are needed in order to improve pore-free microstructures. In view of this, transparent glass matrices are embedded with ferroic materials namely BaTiO3 and the combined optical and electrical results would be useful for future promising optoelectronic materials by means of oneto- many applications. Keywords: Ferroelectric; glassceramics; optical absorption; impedance; dielectric; FTIR

Effect of Chlorides Content on the Structure and Properties of Porous Glass Ceramics Obtained from Siliceous Rock.

Porous glass-ceramic materials are used in the construction engineering and repair of various objects. The article investigates the method for obtaining porous glass ceramics from siliceous rock with a high calcite content. To obtain samples with an even fine porous structure, a small amount (≤0.386%) of chloride (NaCl, KCl, MgCl2·6H2O, CaCl2) was added to the charge mixture. At the first stage, mechanochemical activation of raw materials was carried out. Siliceous rock, Na2CO3 and additives (chlorides) were grinded together in a planetary ball mill. The resulting charge was annealed at a temperature of 850 °C. The influence of the type and amount of chloride on the properties of the charge mixture and glass ceramics has been defined by thermal analysis (TA), X-ray diffraction (XRD), scanning electron microscopy (SEM), etc. The chlorides in the charge mixture decreased the calcite’s decarbonization temperature and had an effect on the macro- and microstructure of the material. As a result, samples of glass ceramics with an even finely porous structure in the form of blocks were obtained. The samples consist of quartz, wollastonite, devitrite, anorthoclase and an amorphous phase. On average, 89–90% of the resulting material consists of with small pores. The apparent density of the samples is in the range of 245–267 kg/m3. Bending and compressive strength reaches 1.75 MPa and 3.8 MPa, respectively. The minimum thermal conductivity of the modified samples is 0.065 W/(m∙°C). The limiting operating temperature is 860 °C, and the minimum thermal shock resistance is 170 °C. The material has a high chemical stability. They can be used as thermal insulation for some types of industrial and civil facilities.

Self‐reduction and enhanced luminescence in transparent Mn2+‐doped mullite glass‐ceramics derived from EMT‐type zeolite

AbstractMn2+ activated glass‐ceramic (GC) has received tremendous attention in the exploration of luminescent materials for solid‐state lighting due to the high stability, broad red emission, and low toxicity. However, the doped Mn2+ ions still suffer from the oxidation and uncontrollable ions migration during the melting process of conventional preparation techniques, which is detrimental to the luminescence performance. Herein, transparent Mn2+‐doped mullite GCs have been prepared at low temperature (∼850°C) via the spark plasma sintering of EMT‐type zeolite. The GC samples show typical red emission peaking at 620 nm that can be assigned to spin‐forbidden 4T1(G)→6A1(S) transition of Mn2+ located in the octahedral coordination site of the host. Owing to the charge compensation mechanism and produced oxygen vacancies, the self‐reduction of Mn3+ to Mn2+ ions is realized and the oxidization is inhibited. The mullite nanocrystals acted as additional scattering centers introduce Rayleigh scattering to enhance the emission intensity. Moreover, benefitted from the established mullite nanocrystals network, the Mn2+‐doped GCs exhibit improved thermal conductivity up to 1.79 W K−1 m−1 and more excellent mechanical properties than conventional GCs, simultaneously.

Effect of MgO/Al2O3 ratio on the crystallization behaviour of Li2O–MgO–Al2O3–SiO2 glass-ceramic and its wettability on Si3N4 ceramic

The composition governs the crystallization ability, the type and content of crystal phases of glass-ceramics. Glass-ceramic joining materials have generated more research interest in recent years. Here, we prepared a novel Li2O–MgO–Al2O3–SiO2 glass-ceramic for the application of joining Si3N4 ceramics. We investigated the influence of the MgO/Al2O3 composition ratio on microstructure and crystallization behaviour. The crystallization kinetics demonstrated that the glasses had excellent crystallization ability and high crystallinity. β-LiAlSi2O6 and Mg2SiO4 were precipitated from the glass-ceramics, and the increase of MgO concentration was conducive to the precipitation of Mg2SiO4. Among the glass-ceramic samples, the thermal expansion coefficient of LMAS2 glass-ceramic was 3.1 × 10−6/°C, which was very close to that of Si3N4 ceramics. The wetting test showed that the final contact angle of the glass droplet on the Si3N4 ceramic surface was 32° and the interface was well bonded.

Spatially Resolved Temperature Distribution in a Rare-Earth-Doped Transparent Glass-Ceramic.

Knowing the temperature distribution within the conducting walls of various multilayer-type materials is crucial for a better understanding of heat-transfer processes. This applies to many engineering fields, good examples being photovoltaics and microelectronics. In this work we present a novel fluorescence technique that makes possible the non-invasive imaging of local temperature distributions within a transparent, temperature-sensitive, co-doped Er:GPF1Yb0.5Er glass-ceramic with micrometer spatial resolution. The thermal imaging was performed with a high-resolution fluorescence microscopy system, measuring different focal planes along the z-axis. This ultimately enabled a precise axial reconstruction of the temperature distribution across a 500-µm-thick glass-ceramic sample. The experimental measurements showed good agreement with computer-modeled heat simulations and suggest that the technique could be adopted for the spatial analyses of local thermal processes within optically transparent materials. For instance, the technique could be used to measure the temperature distribution of intermediate, transparent layers of novel ultra-high-efficiency solar cells at the micron and sub-micron levels.

NaLaMo2O8:Yb3+, Er3+ transparent glass ceramics: Up-conversion luminescence and temperature sensitivity property

A novel transparent Yb3+/Er3+ co-doped NaLaMo2O8 glass ceramics (GCs) with borosilicate glass as the matrix were prepared via glass melting and subsequent controlled crystallization method, and the light transmission property, phase structure, microstructure and up-conversion (UC) performance were characterized by XRD, TEM, transmittance spectroscopy and photoluminescence spectrum. A decrease in the lattice parameter of NaLaMo2O8 in GC sample was verified by XRD Rietveld method, indicating the successful incorporation of Yb3+/Er3+ ions in the Na/La-site of NaLaMo2O8 phase. The UC emission intensity of transparent GCs was significantly enhanced compared to precursor glass. The green light emission in the UC is a three-photon absorption process. The 2.0Yb3+/0.1Er3+(mol%) co-doped GC sample shows the maximum absolute sensitivity of 1.406% K−1 at 473 K, which implies that the as-prepared GC exhibits potential application prospects in the field of optical temperature sensing.