Synthesis and Characterization of Eu3+ Doped CaO-Nb2O5-SiO2 Glass-Ceramics

2014 ◽  
Vol 1030-1032 ◽  
pp. 185-188
Author(s):  
Qiong Song ◽  
Hong Bo Zhang ◽  
Xiao Wei Zhu ◽  
Chun Hui Su
Keyword(s):  
Heat Treatment ◽  
Glass Ceramic ◽  
Treatment Time ◽  
Glass Ceramics ◽  
Emission Peak ◽  
Infrared Light ◽  
Luminescence Spectra ◽  
Excitation Wavelength ◽  
Two Stage ◽  
Ceramic Phase

The glass-ceramics containing nanocrystalline CaNb2O6phase in the 35%SiO2-25%Nb2O5-20%CaO-15BaO-5%Eu2O3(wt%) glass system were prepared by the melt-quench technique followed by a two-stage controlled heat treatment. Samples were characterized by differential thermal analysis, X-ray diffraction, scanning electron microscope, spectrophotometer and fluorescence spectrophotometer. The results shown that glass ceramic phase is CaNb2O6, grain size is about 30 nm, The two-stage controlled heat treatment is beneficial to control of the number and size of grains, thus affecting the transparency of glass ceramic and luminescence properties. The transmittance of the glass ceramics can be up to 80% in the near-infrared light area. The luminescence spectra of Eu3+-doped glass and glass–ceramics were recorded at 394 nm excitation wavelength and the luminescence intensity is found to be increased with heat-treatment time due to increase in crystallinity. Fluorescence spectrum showed 4 emission peak, which located in the 578 nm (5D0-7F0), 592 nm (5D0-7F1), 615 nm (5D0-7F2) and 654 nm (5D0-7F3), Eu3 +emission peak intensity in the glass ceramic sample were greater than the substrate glass.

Investigations of lithium-chloro-borate glass-ceramic and its elastic properties

2010 ◽  
Vol 88 (8) ◽  
pp. 569-574 ◽  
Author(s):  
Y. Shivaprakash ◽  
R. V. Anavekar
Keyword(s):  
Heat Treatment ◽  
Elastic Properties ◽  
Glass Ceramic ◽  
Treatment Time ◽  
Poisson Ratio ◽  
Glass Ceramics ◽  
Heat Treatment Time ◽  
Shear Moduli ◽  
Ir Studies ◽  
Precursor Glass

Elastic properties and microstructural studies of 0.3Li2O-0.2LiCl-0.5B2O3 glass-ceramics have been carried out for a precursor glass prepared using the rapid melt quenching technique. Quenched glasses were heat treated (by three step process) at 150 °C for 2, 4, 6, and 8 h. Scanning electron microscopy and X-ray diffraction studies clearly indicate gradual growth of different phases in the glass matrix with increasing time of heat-treatment. IR studies reveal the structural modification in the network as the precursor glass transformed into glass-ceramic. Elastic properties have been measured by performing ultrasonic wave velocity measurements at a frequency of 10 MHz. Longitudinal and shear moduli of the samples tend to increase with heat-treatment time. However, the bulk modulus is almost insensitive to heat treatment. The Debye temperature was found to increase, and the Poisson ratio lies in the range 0.2–0.3 (typical for covalently bonded networks) with an increase in heat-treatment time.

Synthesis and Characterization of Eu3+-Doped Transparent Glass-Ceramics Containing Nanocrystalline AlNbO4

2014 ◽  
Vol 1004-1005 ◽  
pp. 73-76
Author(s):  
Qiong Song ◽  
Chun Hui Su ◽  
Hong Bo Zhang ◽  
Jing Shao ◽  
Xiang Yu Zou ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Crystalline Phase ◽  
Treatment Time ◽  
Red Light ◽  
Glass Ceramics ◽  
Luminescence Spectra ◽  
X Ray Diffraction ◽  
Transparent Glass ◽  
Doped Glass

The transparent glass-ceramics containing nanocrystalline AlNbO4 phase in the 25Al2O3-27Nb2O5-40SiO2-7Na2O-2Eu2O3(wt%) glass were prepared by the melt-quench technique followed by a two-stage controlled heat treatment. Crystalline phase were indentified using X-ray diffraction (XRD) which AlNbO4 phase was found. Scanning electron microscopy (SEM) was used to image the crystalline phase morphologies. The luminescence spectra of Eu3+-doped glass and glass-ceramics were recorded at 393 nm exciation wavelength and the luminescence intensity is found to be increase with heat-treatment time due to increase in crystallinity. The high intensity ratio of 5D0-7F2 to 5D0-7F1 indicates that the Eu3+-doped nanocrystalline AlNbO4 glass-ceramics are promising candidate materials as red-light source.

Crystallization and dielectric properties of SrO–BaO–Nb2O5–GeO2 tungsten–bronze glass–ceramics

2001 ◽  
Vol 16 (7) ◽  
pp. 2057-2063 ◽  
Author(s):  
Jiin-Jyh Shyu ◽  
Hsin-Wei Peng
Keyword(s):  
Heat Treatment ◽  
Dielectric Properties ◽  
Tungsten Bronze ◽  
Glass Ceramics ◽  
Dielectric Behavior ◽  
Dendritic Morphology ◽  
Dielectric Constants ◽  
Two Stage ◽  
Tetragonal Tungsten Bronze ◽  
Stage Heat Treatment

The crystallization and dielectric properties of SrO–BaO–Nb2O5–GeO2 glass–ceramics were investigated. One- and two-stage heat-treatment methods were used to convert the parent glass to glass–ceramics. Strontium barium niobate (SBN) with a tetragonal tungsten-bronze structure formed as the major crystalline phase. When the crystallizing temperature/time was increased, the secondary crystalline BaGe2O5 phase coexisted with SBN. BaGe2O5 formed as a surface layer grown from the surface into the interior of the sample. The dendritic morphology of SBN crystals was examined. The glass–ceramics crystallized by two-stage heat treatment have higher dielectric constants than those crystallized by one-stage heat treatment. The highest dielectric constant that was obtained in the present glass–ceramics was 320. The glass–ceramics showed relaxor-type dielectric behavior.

scholarly journals Bone bonding ability of some borate bio-glasses and their corresponding glass-ceramic derivatives

2012 ◽  
Vol 6 (4) ◽  
pp. 183-192 ◽  
Author(s):  
Fatma Margha ◽  
Amr Abdelghany
Keyword(s):  
Heat Treatment ◽  
Fourier Transform ◽  
Glass Ceramic ◽  
Glass Composition ◽  
Glass Ceramics ◽  
Soda Lime ◽  
Phosphate Solution ◽  
Borate Glasses ◽  
X Ray Diffraction ◽  
X Ray

Ternary borate glasses from the system Na2O?CaO?B2O3 together with soda-lime-borate samples containing 5 wt.% of MgO, Al2O3, SiO2 or P2O5 were prepared. The obtained glasses were converted to their glass-ceramic derivatives by controlled heat treatment. X-ray diffraction was employed to investigate the separated crys?talline phases in glass-ceramics after heat treatment of the glassy samples. The glasses and corresponding glass-ceramics after immersion in water or diluted phosphate solution for extended times were characterized by the grain method (adopted by several authors and recommended by ASTM) and Fourier-transform infrared spectra to justify the formation of hydroxyapatite as an indication of the bone bonding ability. The influence of glass composition on bioactivity potential was discussed too.

scholarly journals Impact of Morphology and Microstructure on the Mechanical Properties of Ge-As-Pb-Se Glass Ceramics

2020 ◽  
Vol 10 (8) ◽  
pp. 2836 ◽  
Author(s):  
Rashi Sharma ◽  
Rebecca Welch ◽  
Myungkoo Kang ◽  
Claudia Goncalves ◽  
Cesar Blanco ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Vickers Hardness ◽  
Glass Ceramic ◽  
Volume Fraction ◽  
Glass Ceramics ◽  
Post Heat Treatment ◽  
Base Glass ◽  
Parent Glass ◽  
Crystal Phases

The impact of base glass morphology and post heat-treatment protocol on the mechanical properties (Vickers hardness and Young’s modulus) of a multi-component glass-ceramic was examined. Two parent chalcogenide glasses with identical composition but varying morphology (homogeneous and phase separated) were evaluated for their mechanical properties following identical thermal processing to induce crystallization. The nucleation and growth rates of the starting materials were compared for the two glasses, and the resulting crystal phases and phase fractions formed through heat treatment were quantified and related to measured mechanical properties of the glass ceramics. The presence of a Pb-rich amorphous phase with a higher crystal formation tendency in the phase-separated parent glass significantly impacted the volume fraction of the crystal phases formed after heat-treatment. Pb-rich cubic crystal phases were found to be dominant in the resulting glass ceramic, yielding a minor enhancement of the material’s mechanical properties. This was found to be less than a more moderate enhancement of mechanical properties due to the formation of the dominant needle-like As2Se3 crystallites resulting from heat treatment of the homogeneous, commercially melted parent glass. The greater enhancement of both Vickers hardness and modulus in this glass ceramic attributable to the high-volume fraction of anisotropic As2Se3 crystallites in the post heat-treated commercial melt highlights the important role base glass morphology can play on post heat-treatment microstructure.

In Vitro Bioactivity Characterization of Machinable Glass Ceramics Containing 85wt% Na-mica and 15wt% Fluorapatite

2006 ◽  
Vol 309-311 ◽  
pp. 325-328 ◽  
Author(s):  
Gültekin Göller ◽  
Ipek Akin ◽  
A. Kahraman ◽  
Erdem Demirkesen ◽  
M. Urgen
Keyword(s):  
Thin Film ◽  
Heat Treatment ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Xrd Analysis ◽  
Crystallization Time ◽  
In Vitro Bioactivity ◽  
Treatment Procedures

In this study; in-vitro bioactivity characterization of machinable glass-ceramics having 85 wt% sodium mica (NaMg3AlSi3O10F2) and 15 wt% fluoroapatite has been carried out. Two different heat treatment procedures are applied to the machinable glass-ceramics. The first one is nucleation at 610°C for 2 hours and crystallization at 1000°C for 3 hours and the second is nucleation at 610°C for 2 hours and crystallization at 1000°C for 4 hours. It is observed that increasing the crystallization time to 4 hours resulted in the increasing the formation of hydroxyapatite layer on surface. According to the microstructural investigations, the morphology of the precipitated crystals are different. In addition, the speed of the precipitation of hydroxyapatite is higher in glass-ceramic B than A. Thin film XRD analysis supports these results.

Formation of NaNbO3 Crystals in Dielectric Glass and Glass-Ceramics of a Na2O-Nb2O5-Al2O3-SiO2 System

2008 ◽  
Vol 55-57 ◽  
pp. 229-232 ◽  
Author(s):  
S. Thongsaeng ◽  
Anuson Niyompan ◽  
Rungnapa Tipakontitikul ◽  
Kamonpan Pengpat
Keyword(s):  
Heat Treatment ◽  
Treatment Time ◽  
Glass Ceramics ◽  
Glass Production ◽  
Nucleating Agent ◽  
Aluminum Silicate ◽  
Phase Identification ◽  
Dielectric Glass ◽  
Xrd Patterns ◽  
Glass Compositions

Dielectric glass and glass-ceramics were derived from Na2O-Nb2O5-Al2O3-SiO2 system. Small amount of TiO2 were also introduced into glass compositions to study crystallization behavior of the glass with present of this nucleating agent. Conventional melt-quenching technique was employed for a glass production and the selected bulk glass samples were subjected to the heat-treatment process at appropriate temperature. After six different glass compositions were produced, and by observation with necked eyes, all obtained glass samples are in light brown color and some samples were opaque due to crystallization took place during quenching. Phase identification through XRD patterns show that there were 3 phases, NaNbO3, NaNbO8 and a sodium aluminum silicate compound, found in those opaque glass samples. NaNbO3 is a predominant phase in all samples. Fortunately, clear transparent glass was obtained from the composition with no TiO2 addition. Heat treatment of this glass did not induce phase change, three aforementioned phases still present. Increasing heat treatment time promoted a higher of observed intensity of NaNbO3. But the NaNbO3 crystalline size was not significantly developed with time. The dielectric response of the NaNbO3 crystals in the glass-ceramics samples are influenced by presence of other crystalline phases.

Zn2+- Controlled Crystallization and Microstructure in K-Li-Mg-B-Si-Al-F Glass

MRS Advances ◽  
2018 ◽  
Vol 3 (60) ◽  
pp. 3525-3533 ◽  
Author(s):  
Mrinmoy Garai ◽  
Anoop K. Maurya ◽  
Shibayan Roy
Keyword(s):  
Heat Treatment ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Ceramic ◽  
Vickers Microhardness ◽  
Glass Ceramics ◽  
Network Modifier ◽  
Base Glass ◽  
Controlled Crystallization

Abstract Text:The crystallization of (9-X) K2O-1Li2O-12MgO-10B2O3-40SiO2-16Al2O3-12MgF2-X PbO/BaO/ZnO (X =0/5) composition (wt.%) were studied by means of dilatometry, DSC, XRD, SEM and microhardness analysis. Density of base K-Li-Mg-B-Si-Al-F glass (2.59 g.cm–3) is found to be increased on addition of the network modifier oxides PbO, BaO and ZnO content. Addition of Pb2+, Ba2+ and Zn2+ furthermore increased the glass transition temperature (Tg.). A characteristic exothermic hump is found to be appeared in DSC thermograph at the temperature range 800-950°C; and that is ascribed to the formation of crystalline phase fluorophlogopite mica, KMg3(AlSi3O10)F2. Opaque glass-ceramics were prepared from K-Li-Mg-B-Si-Al-F glasses (with and without containing PbO, BaO and ZnO content) by controlled heat-treatment at 1000°C. Interlocked type microstructure combined of flake like fluorophlogopite mica crystals is obtained in ZnO-containing K-Li-Mg-B-Si-Al-F glass-ceramic; and such microstructural pattern is ascribed to cause large thermal-expansion (>11.5×10-6/K, 50-800°C).Vickers Microhardness of base glass-ceramic (5.12 GPa) is increased when contains ZnO (5.26 GPa). ZnO-containing boroaluminosilicate glass-ceramic is, hence, considered with potential interest as they can exhibit the microcrack resistivity in high temperature recycling operation (like SOFC).

BISMUTH NIOBATE-BASED GLASS-CERAMICS FOR DIELECTRICALLY LOADED MICROWAVE ANTENNAS

2008 ◽  
Vol 01 (01) ◽  
pp. 25-30 ◽  
Author(s):  
MEHDI MIRSANEH ◽  
BEATA ZALINSKA ◽  
OLIVER P. LEISTEN ◽  
IAN M. REANEY
Keyword(s):  
Heat Treatment ◽  
Resonant Frequency ◽  
Glass Ceramic ◽  
Heat Treatment Temperature ◽  
Glass Ceramics ◽  
Treatment Temperature ◽  
Ceramic Processing ◽  
Ceramic System ◽  
Microwave Antennas ◽  
Microwave Applications

A castable, low melting temperature glass-ceramic system (30% Bi 2 O 3, 30% Nb 2 O 5, 30% B 2 O 3 and 10% SiO 2, in mol%) suitable for microwave applications is fabricated and characterized. Depending on heat treatment temperature, the glass ceramic exhibits permittivity, 15 ≤ ε r ≤ 41, temperature coefficient of resonant frequency of -160 ≤ τ f ≤ +100 MK -1 and microwave quality factor of 300 GHz ≤ Qf ≤ 15000 GHz . The highest Qf occurs at 960°C heat treatment with ε r = 15, τ f = -80 MK -1 and Qf = 15000 GHz . Applications are envisaged such as castable dielectrically-loaded antenna pucks, removing the need for complex ceramic processing.

Development of Machinable Glass-Ceramic without Nucleating Agents

2015 ◽  
Vol 830-831 ◽  
pp. 436-439
Author(s):  
C. Venkateswaran ◽  
Amarnath Padala ◽  
H. Sreemoolanadhan ◽  
M.R. Ajith ◽  
Mariamma Mathew ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Heat Treatment Condition ◽  
Aluminum Silicate ◽  
Nucleating Agents ◽  
Treatment Conditions ◽  
Magnesium Aluminum Silicate ◽  
Optimum Heat ◽  
Alumino Silicate

Mica containing glass-ceramic is prepared by crystallizing magnesium alumino silicate glass between 600°C and 1100°C without the use of any additives or nucleating agents. Effects of ceramization heat treatment conditions on phase constitution and microstructures are analyzed using XRD and HRSEM respectively. Developed glass-ceramics have been analyzed for its microhardness and machinability. Optimum heat treatment condition for achieving uniformly distributed fluorophlogopite phase essential for machinability, and at the same time, magnesium aluminum silicate phase for increasing the hardness, is presented.

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