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Sintering,crystallization and dielectric properties of CaO-B_2O_3-SiO_2 system glass ceramics

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Journal of Central South University 2012年第8期19卷 2101-2106页

作者：戴斌朱海奎周洪庆许贵军岳振星 State Key Laboratory of Materials-Oriented Chemical Engineering(Nanjing University of Technology) College of Materials Science and Engineering Nanjing University of Technology State Key Laboratory of New Ceramic and Fine Processing(Tsinghua University)

CaO-B203-SiO2 （CBS） glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is found that there are SiO2 and some unknown phases in CBS glass melting liquid from 1 300 ℃ to 1 500 ℃ and the amount of these phases decreases with the increase of the melting temperature. The CBS glass melted at 1 450 ℃ could be sintered from 830 ℃ to 930 ℃ and the bulk densities of the samples are all higher than 2.4 g/cm^3. From the points of the properties and energy conservation, the melting temperature of 1 450 ℃ is the optimal melting temperature. The glass ceramic sintered at 850 ℃ exhibits better dielectric properties： er=6.33, tan6=2.2×10^-3 at 10 GHz, and the major phases of the samples are CaSiO3, CaB2O4 and SiO2.

关键词： glass ceramics CaO-B2O3-SiO2 sintering dielectric properties microstructure

Concentration quenching in transparent glass ceramics containing Er^(3+):NaYF_4 nanocrystals

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Science China(Physics,Mechanics & Astronomy) 2012年第7期55卷 1148-1151页

作者： HUANG XingYong CHEN DaQin LIN Lin WANG ZheZhe WANG YuanSheng FENG ZhuoHong ZHENG ZhiQiang College of Physies and Energy Fujian Normal UniversityFuzhou 350007China Fujian Institute of Research on the Structure of Matter Chinese Aeademy of SciencesFuzhou 350002China

In this work, we have studied the concentration quenching in transparent glass ceramics containing Er^3＋：NaYF4 nanocrystals. For different concentrations, the emission spectra and decay curves of the ^4I/3/2 → ^4I15/2 emission were measured. The Er-concentration dependence of integrated intensity and lifetime of ^4I13/2→^4I15/2 emission are showed. With the increase of the Er^3＋ doping concentration, the 1.5 μm fluorescence emission first increases, then decreases, and the lifetime falls gradually. With 980 nm excitation, the efficiency of the energy transfer from Er^3＋ to quenching centers reaches 73.73% for the sample with 4 mol% Er^3＋. Meanwhile, owing to the relation of fluorescence integrated intensity and Er-concentration, a dipole-dipole quenching mechanism in the framework of a limited diffusion regime has been proved. Using the limited diffusion case, the critical concentration for quenching has been determined from a fitting equation of the lifetime and Er-concentration. The fit- ting result shows the critical concentration for quenching is higher than the values obtained in Er-doped different glass by an order of magnitude.

关键词： concentration quenching glass ceramics Er^3+ nanocrystals critical concentration

Photoluminescence enhancement induced from silver nanoparticles in Tb^(3+) -doped glass ceramics

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Chinese Optics Letters 2012年第9期10卷 89-91页

作者：毕岗王丽熊巍 Kosi Ueno Hiroaki Misawa 邱建荣 School of Information and Electrical Zhejiang University City College State Key Laboratory of Silicon Materials Zhejiang University Research Institute for Electronic Science Hokkaido University PRESTO Japan Science and Technology Agency

We experimentally verify that surface plasmon （SP） enhances the photoluminescence （PL） of visible light from Tb3＋-doped 60SiO2-20Al2O3-20CaF2：0.3Tb3＋, 20Yb3＋ glass ceramics by using electron beam lithog- raphy to fabricate silver nanoparticles on the surface of the glass ceramics. Numerical calculation for the SP enhancement spectroscopy is achieved by using the finite-difference time-domain algorithm. A PL enhancement of Tb3＋ by as much as 1.6 times is observed. The PL enhancement is mainly due to the coupling of excitation from 7F6 to 5D4 transition dipole of Tb3＋ ion with SP mode induced from the silver nanoparticles.

关键词： Electron beam lithography Finite difference time domain method glass ceramics Nanoparticles Photoluminescence Silver Time domain analysis Ytterbium

An investigation on crystallization property, thermodynamics and kinetics of wollastonite glass ceramics

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Journal of Central South University 2018年第8期25卷 1888-1894页

作者： SI Wei DING Chao School of Materials Science and Engineering Dalian Jiaotong UniversityDalian 116028China Dalian Environmental Monitoring Center Dalian 116023China

Wollastonite glass ceramics were prepared using the reactive crystallization sintering method by mixing waste glass powders with *** crystallization property,thermodynamics,and kinetics of the prepared wollastonite glass ceramics were determined by X-ray diffraction analysis,scanning electron microscopy,energy-dispersive spectroscopy,high-resolution transmission electron microscopy,and differential thermal *** showed that crystals of wollastonite and alumina could be found in the gehlenite through its reaction with silicon *** wollastonite crystals showed a lath shape with a certain length-to-diameter *** crystals exhibited excellent bridging and reinforcing *** the crystallization process,the aluminum ions in gehlenite diffused into the glass and the silicon ions in the glass diffused into ***,the three-dimensional frame structure of gehlenite was partially damaged to form a chain-like *** results of crystallization thermodynamics and kinetics indicated that crystallization reaction could occur spontaneously under a low temperature(1173 K),with 20 wt%gehlenite added as the reactive crystallization *** crystallization activation energy was evaluated as 261.99 kJ/mol by using the Kissinger *** compression strength of the wollastonite glass ceramic samples(7.5 cm×7.5 cm)reached 251 MPa.

关键词： glass ceramics crystallization thermodynamics crystallization kinetics

Nanocrystal formation and structure in oxyfluoride glass ceramics

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Chinese Physics B 2005年第9期14卷 1799-1802页

作者：余华赵丽娟孟婕梁沁禹宣伊唐柏权许京军 Photonics Research Center College of Physical Science Nankai University Tianjin 300071 China The MOE Key Laboratory of Advanced Technique & Fabrication for Weak-Light Nonlinear Photonics Materials and Tianjin Key Laboratory of Photonics Materials & Technology for Information Science Nankai UniversityTianjin 300457 China

The up-conversion luminescent property of the oxyfluoride glass ceramics 30SiO2·15Al2O3· （50-x）PbF2·xCdF2 doped with 4ErF3·1YbF3 has been investigated. Up-conversion luminescent intensity of Er^3＋ ions increased obviously after heat-treatment due to co-doping with CdF2. The structure model of nanocrystals PbxCdl-xF2 was determined and the effect of CdF2 in oxyfluoride glass ceramics was explained by the analysis of x-ray diffraction data. Different nucleation temperatures of samples with different compositions were obtained by differential thermal analysis curves and the results showed the growth process of different nanocrystals in glass ceramics.

关键词： up-conversion glass ceramics structure

Effect of glass network modifier R_2O(R=Li, Na and K) on upconversion luminescence in Er^(3+)/Yb^(3+) co-doped NaYF_4 oxyfluoride glass-ceramics

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Journal of Rare Earths 2015年第8期33卷 830-836页

作者：高源胡曰博任鹏周大成邱建备 Faculty of Material Science and Engineering Kunming University of Science and Technology Faculty of Mechanical and Electrical Engineering Kunming University of Science and Technology Key Laboratory of Advanced Materials of Yunnan Province

The effect of glass network modifier R2O （R=Li, Na, K） on upconversion luminescence in Er3＋/yb3＋ co-doped NaYF4 oxyfluoride glass-ceramics was investigated. NaYF4 nanocrystals with different sizes were studied under glass network modifier alkali mental oxide. The nanocrystals size in NaYF4 of Li2O modified samples was 11 nm, whereas in the Na20 and K2O modified sample, the crystal size was 25 and 43 nm, respectively. It was found that red, yellow and green upconversions were observed in SAL, SAN, SAK glass ceramics. The reported results would deepen the understanding of size effects on the lanthanide upcon- version in nanocrystals.

关键词： upconversion luminescence glass network modifier glass ceramics crystallization activation energy rare earths

Effect of Fe_2O_3 on the crystallization behavior of glass-ceramics produced from naturally cooled yellow phosphorus furnace slag

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International Journal of Minerals,Metallurgy and Materials 2017年第3期24卷 316-323页

作者： Hong-pan Liu Xiao-feng Huang Li-ping Ma Dan-li Chen Zhi-biao Shang Ming Jiang Faculty of Environmental Science and Engineering Kunming University of Science and Technology College of Resources and Environment Yunnan Agricultural University

CaO–Al2O3–SiO2(CAS) glass-ceramics were prepared via a melting method using naturally cooled yellow phosphorus furnace slag as the main raw material. The effects of the addition of Fe2O3on the crystallization behavior and properties of the prepared glass-ceramics were studied by differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The crystallization activation energy was calculated using the modified Johnson–Mehl–Avrami equation. The results show that the intrinsic nucleating agent in the yellow phosphorus furnace slag could effectively promote the crystallization of CAS. The crystallization activation energy first increased and then decreased with increasing amount of added Fe2O3. At 4wt% of added Fe2O3, the crystallization activation energy reached a maximum of 676.374 kJ·mol−1. The type of the main crystalline phase did not change with the amount of added Fe2O3. The primary and secondary crystalline phases were identified as wollastonite (CaSiO3) and hedenbergite (CaFe(Si2O6)), respectively. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

关键词： Ceramic materials Chemical activation Crystalline materials Crystallization Differential thermal analysis Furnaces glass ceramics Iron oxides Nucleation Phosphorus Scanning electron microscopy Silicate minerals Slags Thermoanalysis X ray diffraction

Multi-ratio optical thermometry and energy storage characteristics of Yb^(3+)/Er^(3+)/Tm^(3+)doped BaNb_(2)O_(6)transparent glass-ceramics

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Journal of Materials Science & Technology 2023年第7期138卷 138-148页

作者： Junhao Xing Feng Luo Yaoyi Qin Xiaolu Chen Yingying Liang Zhixin Gao Fei Shang Huarui Xu Guohua Chen School of Material Science and Engineering Guangxi Key Laboratory of Information MaterialsGuilin University of Electronic TechnologyGuilin 541004China

In order to meet the needs of new materials gradually developing towards miniaturization,integration,and light weight,multifunctional BaNb_(2)O_(6):Yb^(3+)/Er^(3+)/Tm^(3+)transparent glass-ceramics were success-fully prepared by melt quenching and controllable *** structure,luminescence,and en-ergy transmission were *** the opposite temperature dependence of the Tm^(3+)emission band and the corresponding large energy level gap,a maximum relative sensitivity of 2.3%K^(-1)based on thermal coupling levels(TCLs)is obtained in a wide temperature range(298-673 K).The multi-ratio optical thermometry based on TCLs and non-TCLs is successfully realized by using the different emission bands of double emission centers,which makes it possible for self-reference optical temperature measurement *** addition,the transparent glass-ceramic exhibits excellent electrical properties under 700 kV cm^(-1)electric field:high discharge energy density(W_(d)=0.99 J cm^(-3)),huge instantaneous power density(225.3 MW cm^(-3)),and ultra-fast discharge rate(T_(0.9)≤15.8 ns).The prepared glass-ceramic is expected to be a new type of lead-free multifunctional photoelectric material for temperature sensors and transparent electronic devices.

关键词： glass ceramics Luminescence Optical thermometry Energy storage

Magnetic glass-ceramics

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Journal of Advanced ceramics 2012年第2期1卷 138-143页

作者： Viorel SANDU Mirela Sidonia NICOLESCU Victor KUNCSER Raluca DAMIAN Elena SANDU National Institute of Materials Physics Magurele 077125Romania “Horia Hulubei”National Institute of Nuclear Physics and Engineering Magurele 077125Romania

We present the magnetic properties of magnetic glass ceramics obtained by crystallization of Fe containing borosilicate *** types of nucleators have been used:Cr2O3 and *** role of the nucleators proved to be crucial in the size and morphology of the crystallites developed within glassy matrix as well in the magnetic *** former stimulates the growth of regular single crystals uniformly dispersed within the matrix whereas the latter leads to the formation of grains made of tiny(30 nm),*** magnetic response depends on the amount of Fe ions left dispersed within glassy matrix as paramagnetic *** P2O5 leads to the best structural magnetite,almost 42%of Fe ions are left dispersed in the matrix without magnetic *** the case of Cr2O3,the paramagnetic Fe is decreased to 12%but structural deficiency in the occupancy of the Fe sites of magnetite is revealed by Mössbauer spectroscopy.

关键词： glass ceramics Fe3O4 Mössbauer spectroscopy grain growth