Crystallization effect on Tm3+–Yb3+ codoped SBN glass ceramics (original) (raw)
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Synthesis and characterization of strontium and barium bismuth borate glass-ceramics
Journal of Non-crystalline Solids, 2014
Glass ceramics in the 20MO.55Bi 2 O 3 .25B 2 O 3 (M = Sr, Ba) system were prepared by conventional melt quenching method, followed by heat treatment. XRD patterns show that the crystalline phase boron sillenite (Bi 24 B 2 O 39) was formed on thermal treatment. The variation in the microstructure of the sample as a function of crystallization temperature was studied using scanning electron microscopy. The structural changes due to heat-treatment of the glasses have been explained on the basis of the changes in FT-IR and FT-Raman spectra. The glass ceramics in the present study have relatively high dielectric constant and low dielectric loss.
Formation of Nd(3+) doped Strontium Barium Niobate nanocrystals by two different methods
The study of two different methods to obtain Strontium Barium Niobate nanocrystals has been carried out. Previously, Nd 2 O 3 doped SrO-BaO-Nb 2 O 5 -B 2 O 3 glasses were fabricated using the melt quenching process. In the first method, a thermal treatment in an electrical furnace at 620°C was used to obtain glass ceramic samples. In the second one, the nanocrystals were obtained under continuous Ar laser irradiation in a localized zone in the glass sample. The X-ray diffraction patterns confirmed the formation of SBN nanocrystals in both cases. The optical measurements indicate the incorporation of Nd 3+ ions into the nanocrystals which produces an increment of the luminescence intensity. Moreover, a calibration with the temperature has been carried out for the ratio of the Nd 3+ emissions. This result could let to control the temperature of the laser irradiated zone.
Structure and nonisothermal crystallisation of glasses in the BaO–B2O3–TiO2 system
The structure and devitrification behaviour of barium borotitanate glasses, examined by Fourier transform infrared spectroscopy, differential thermal analysis and x-ray diffraction, are reported. Glass compositions are expressed by the formula: (50-x/2)BaO.(50-x/2)B 2 O 3 .xTiO 2 with x=4, 8 and 16. Titanium acting as glassformer gives a more polymerised structure increasing the glass stability with respect to devitrification. The nonisothermal devitrification of the studied glasses occurs in one or two steps depending on the TiO 2 content in the glass composition and the specific surface area of the sample. The surface crystallisation was found to be dominant for all glasses. The investigated glasses devitrify forming b-BaB 2 O 4 microcrystals as the main crystalline phase.
Journal of Asian Ceramic Societies, 2017
Two series of glasses were synthesized by conventional rapid melt-quench method for different glass systems 55[(Pb x Bi 1-x).TiO 3 ]-44[2SiO 2 B 2 O 3 ] and 65[(Pb x Bi 1-x).TiO 3 ]-34[2SiO 2 B 2 O 3 ] doped with 1 mole percent of La 2 O 3. X-ray diffraction study of synthesized glass sample shows amorphous nature while the glass ceramic sample revealed a cubic crystal structure due to devitrification of the glass as major crystalline phase of bismuth titanium oxide. X-ray absorption spectroscopy measurements in transmission mode were carried out and confirm the maximum value of absorption coefficient, 3.05 at energy 13450 eV for lead free glass ceramic sample. Scanning electron microscopy and contact angle measurements were also performed to explain the surface morphology. Energy dispersive X-ray analysis confirmed the presence of grains of bismuth titanium oxide and its elemental analysis with O, Ti, Si, Bi nanoparticles. The inclusions of La 2 O 3 results in development of well interconnected crystallites were formed as major phase of bismuth titanium oxide.
Journal of Non-crystalline Solids, 2008
Structural and optical properties of stable glasses in the Y 2 O 3 -CaO-B 2 O 3 system, containing the same Y/Ca ratio as the YCa 4 O͑BO 3 ͒ 3 ͑YCOB͒ crystal, were determined from Raman and reflectance infrared spectroscopy. Changes in optical functions with composition are associated with an increase in the number of non-bridging oxygen and to calcium/yttrium oxides content. Refractive indexes values ͑from 1.597 to 1.627 at =2 m͒ are in good agreement with those of the YCOB crystal, an indication that these glasses are potential candidates for optical applications due to their ease of shaping as large bulk samples or fibers.
Evolution of nanocrystalline BaBi2Nb2O9 in Li2B4O7 BaO Bi2O3 Nb2O5 glass system
Journal of Non-crystalline Solids, 2007
Transparent glasses and glass nano crystal composites (GNCs) of various compositions in the system (100 À x)Li 2 B 4 O 7 -x(BaO-Bi 2 O 3 -Nb 2 O 5 ) (where x = 10, 20, and 30 in molar ratio) were fabricated via splat-quenching technique. The glassy nature of the asquenched samples was established by differential thermal analyses. X-ray powder diffraction and transmission electron microscopic (TEM) studies confirmed the formation of layered perovskite BBN via a fluorite like phase. TEM studies revealed the presence of 10 nm sized spherical crystallites of fluorite like BaBi 2 Nb 2 O 9 phase in the glassy matrix of Li 2 B 4 O 7 (LBO). The influence of composition on the dielectric and the optical properties (transmission, optical band gap) of these samples has been investigated.
New Transparent Nano-Glass-Ceramics of SiO 2 and CaF 2 doped SrO-B 2 O 3 Glass
Silicon, 2015
Glasses from the strontium borate system of the basic composition 45 % SrO-55 % B 2 O 3 together with samples doped with 2 or 5 % of either SiO 2 or CaF 2 , were prepared using the melt annealing technique. The prepared samples were characterized by means of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). XRD has indicated the amorphous nature of all glasses within the studied compositional range. Differential thermal analysis (DTA) studies were undertaken to measure the glass transition and crystallization temperatures and to identify the detailed thermal properties of the prepared glasses. A thermal heat treatment regime was conducted for all the samples. The base strontium borate glass is observed to be transformed to a distinct glass-ceramic derivative containing a crystalline strontium borate (SrO. B 2 O 3) phase. The other heat treated samples containing either 2, 5 % SiO 2 or 2 & 5 % CaF 2 show nano-behavior or transformation to nano-glass-ceramic formation on examination by x-ray diffraction. FTIR spectra have indicated that the introduction of either SiO 2 or CaF 2 with the levels of 2 % or 5 % causes no changes in the main IR vibrational bands in their number or position which contain vibrational modes due to tetrahedral and triangular borate groups. Glass samples were subjected to successive gamma irradiation to doses of 2, 6
Materials Letters, 2002
Nanocrystalline powders of strontium–barium–niobate (SBN) with the composition SrxBa1−xNb2O6 (with x=0.4, 0.5 and 0.6) have been prepared using a single step chemical synthesis process starting from a precursor solution constituting of triethanolamine (TEA), niobium–tartarate and EDTA complexes of strontium and barium ions. The complete dehydration of the TEA-soluble metal ion complex precursor solution through heating yield in a fluffy, carbonaceous
Crystallization behavior of new transparent glass-ceramics based on barium borate glasses
Journal of the Ceramic Society of Japan, 2008
This paper describes the preparation of several new transparent and very fine crystal glass-ceramics from the BaO-B2O3 system utilizing an appropriate additive of fluorides, partial replacement of B2O3 by SiO2, and introducing nucleating agents, such as TiO2. The physical properties of the prepared materials and the changes with varying base glass compositions and heat treatment programs were investigated. The thermal behavior and microstructure of the developed phases were characterized using DTA, XRD, and SEM. Glass-ceramics with marked transparency were prepared. These transparent derivatives owe their transparency to the distinctive properties of the nano-crystalline samples. The dielectric constant of transparent glassceramics samples at 100 kHZ were between 14-20, which is very suitable for a wide range of applications, such as the highspeed switching of large-scale integrators. It was found that the addition of Fand SiO2 greatly influenced the transparency of the produced glass-ceramics. Also, the addition of TiO2 greatly enhanced transparency, in spite of increasing cutoff in the UV region to a higher wavelength.
Transfer and back transfer processes in Yb3+–Er3+ codoped Strontium Barium Niobate glass-ceramics
The forward and backward energy transfer processes in Strontium Barium Niobate glass-ceramics double doped with Yb 3 þ and Er 3 þ ions have been studied. In these samples the rare earth ions are incorporated into the nanocrystals with an average size of 50 nm. Using laser excitation at 950 nm is possible to excite selectively the Yb 3 þ ions and detect emission due to these ions (at 1040 nm) or combined with the Er 3 þ ions (at 980 nm). In previous works, the energy transfer processes between these ions in different matrices have been analyzed in order to improve the emission at 1550 nm, but these analyses are restricted to fast migration processes among ions. In this fast migration regimen the results are valid only for larger concentrations. However, in this work the dynamics of these transfer processes has been carried out using a general method called ''transfer function model''. The parameters which characterize these processes have been obtained and it has been possible to explain the important increase of the emission at 1550 nm due to the co-doping with Yb 3 þ ions. This analysis is valid for any range of doping concentrations.