- Compositional dependence of the boson peak and fractal dimensionality in Calcium Aluminate glasses prepared by aerodynamic levitation and CO2-laser melting
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A series of glasses have been prepared in the binary xCaO – (1 – x)Al2O3, (x = 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75 and 0.80) by the aerodynamic levitation technique combined with CO2-laser melting. By utilizing Raman spectroscopy, we systematically followed the compositional dependence of the observed low-frequency vibrations, namely the Boson Peak. It was found that the BP frequency is systematically dependent on altering CaO content, exhibiting a minimum close to the eutectic composition for the binary Calcium Aluminate glassy system. This characteristic was also observed in the elucidation of fractal dimensionality in Calcium Aluminate glasses. By utilizing the fracton model based on low-frequency vibrations, we found that the compositional dependence of the fractal dimension is similar to the one observed for the BP and that the eutectic point can serve as a point not only for investigating relevant structural changes occurring in glasses, but also for changes manifested in the low-frequency regime. The results are discussed in the context of relevant theories of the field.
- Kalampounias, Angelos G.,Nasikas, Nektarios K.
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- Selective self-redox and crystal field modulation for enhanced and tuned broadband emission in chromium-doped aluminate glasses
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The emerging era of big data has stimulated the development of optical materials with broad emission region to allow data transmission of higher capacity and speed. Here, broadband emission, almost covering the region of 650-1500 nm, was realized by doping transition metal ions into versatile aluminate glasses, in which abundant microstructures and certain oxidizing capacity could be guaranteed to enrich emissions. Furthermore, we aimed to improve spectroscopic properties via the simultaneous self-redox and crystal field modulation of Cr ions and matrixes, respectively. More emission ions and more efficient centers were created to enhance the emission intensity by more than one order of magnitude. In addition, proper crystal field was created to liberate a new emission band at ～708 nm. The results may allow the development of tunable fiber laser and amplifier using the materials and pave the way to precisely control the valence and crystal field to obtain efficient emission.
- Li, Xingyu,Luo, Haoyang,Wang, Yafei,Wang, Xiu,Cao, Jiangkun,Wang, Liping,Peng, Mingying
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p. 5401 - 5409
(2019/05/21)
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- A mass-spectrometric study of vapor composition and thermodynamic properties of CaO-Al2O3 melts
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The composition and partial pressures of molecular species in vapor over melts of CaO-Al2O3 at 1833-2033 K were determined by Knudsen effusion-mass spectrometry. Negative deviations from ideality were observed for the system. The thermodynamic properties of CaO-Al2O3 melts were expressed by analytical dependences as functions of the temperature and concentration of components of the system.
- Shornikov,Stolyarova,Shul'ts
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