Ionic to covalent glass network transition: Effects on elastic and vibrational properties according to ultrasonic echography and Raman spectroscopy

Mpourazanis, Pantelis; Stogiannidis, G.; Tsigoias, S.; Papatheodorou, George; Kalampounias, Angelos G.

doi:10.1016/j.jpcs.2018.10.010

Cited by 24 publications

(19 citation statements)

References 32 publications

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“…51 Values for the Poisson ratio between 0.1 and 0. namely, low cross-linking density. 51 Here, the reported values for the CA glasses under investigation show a variation between 0.27 and 0.34. This can be considered indicative of a small cross-linkage transformation occurring in these glasses and thus the corresponding glass networks are characterized from low cross-linking density, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The Poisson's ratio seems to be following a somewhat increasing trend with increasing CaO content, whereas the Debye temperature was found to decrease with increasing CaO content. It has been shown that the Debye temperature and the Poisson's ration can be proven very useful tools in order to estimate the cross‐linking density of the glass network 51 . Values for the Poisson ratio between 0.1 and 0.2 are indicative of high cross‐linking, whereas values between 0.3 and 0.5 are indicative of the opposite, namely, low cross‐linking density 51 .…”

Section: Resultsmentioning

confidence: 99%

“…It has been shown that the Debye temperature and the Poisson's ration can be proven very useful tools in order to estimate the cross‐linking density of the glass network 51 . Values for the Poisson ratio between 0.1 and 0.2 are indicative of high cross‐linking, whereas values between 0.3 and 0.5 are indicative of the opposite, namely, low cross‐linking density 51 . Here, the reported values for the CA glasses under investigation show a variation between 0.27 and 0.34.…”

Section: Resultsmentioning

confidence: 99%

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Deconvoluting interrelationships between low‐energy vibrational modes and elastic properties in CaO–Al₂O₃ glasses

Nasikas

Kalampounias

2022

J Am Ceram Soc.

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By employing a nonconventional melting technique, namely, the aerodynamic levitation combined with CO 2 laser melting, we have been able to synthesize a series of glasses in the binary system xCaO − (1 − x)Al 2 O 3 , (x = 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, and 0.80). Utilizing Raman spectroscopy, we have systematically followed the compositionally induced spectral changes in the low-frequency regime of the spectra, the so-called Boson Peak (BP) region, and unraveled interesting interrelationships between the low-energy vibrational modes and the elastic properties of calcium aluminate (CA) glasses. It was found that the BP frequency is not only systematically dependent on altering CaO content by exhibiting a minimum close to the eutectic composition. Interestingly, the above-mentioned compositional dependence of the BP, which is exhibited in the shift of the BP frequency versus the altering CaO content, is also strongly correlated with its elastic properties and seems to follow similar patterns for the binary CA glassy system. The above observations point toward the estimation that the eutectic point can serve as a strong indicator for various physicochemical phenomena taking place in the solid-liquid transition and thus provide new insights in an effort to deconvolute the ambiguous interrelationships occurring in the low vibrational frequency regime of these glasses.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Deconvoluting interrelationships between low‐energy vibrational modes and elastic properties in CaO–Al₂O₃ glasses

Nasikas

Kalampounias

2022

J Am Ceram Soc.

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“…The measurement setup utilized for the simultaneous detection of sound absorption and velocity has been described in (Mpourazanis et al 2019 ; Kalampounias 2020 ; Stogiannidis et al 2020 ). The apparatus consists of two identical broad band piezoelectric transducers (Olympus, nominal center frequency 10 MHz) and a cylindrical thermostated acoustic cell with parallel phases.…”

Section: Methodsmentioning

confidence: 99%

“…The sound velocity is estimated for all concentrations studied by determining the time required for the ultrasound to travel the fixed path length (Mpourazanis et al 2019 ; Kouderis et al 2021 ). The experimental error in velocity measurements is ± 0.01%.…”

Section: Methodsmentioning

confidence: 99%

Molecular relaxation dynamics and self-association of dexamethasone sodium phosphate solutions

2021

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Detailed concentration-dependent measurements of sound absorption and velocity have been performed in dexamethasone sodium phosphate (DSP) aqueous solutions in the MHz frequency range. A single well-resolved relaxation process dominates the experimental acoustic spectra following a Debye-type distribution function. The analysis of the temperature-dependent ultrasonic relaxation data also revealed analogous effect with concentration on the relaxation spectra. All acoustic parameters were estimated by means of a fitting procedure. The behavior of the relaxation frequency and amplitude with concentration allowed us to assign the observed process to self-association mechanism. Combining the ultrasonic and electric conductivity data, the self-association scheme has been established. The thermodynamic constants and the rate of the aggregation due to hydrophobic interactions have been estimated in view of the Eyring's theory. The concentration dependence of relaxation amplitude and characteristic frequency revealed that the presence of additional relaxation processes in the spectra related to additional mechanisms, such as conformational changes and proton-transfer reaction is excluded and the self-association process considered here was found to dominate in this frequency range. The results have been discussed in view of the fair ability of DSP for hydrophobic interactions and aggregate formation in aqueous environment.

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Bright Transparent Scintillators with High Fraction BaCl₂: Eu²⁺ Nanocrystals Precipitation: An Ionic‐Covalent Hybrid Network Strategy toward Superior X‐Ray Imaging Glass‐Ceramics

Liu,

Ran,

Chen

et al. 2023

Advanced Science

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Metal halide crystals are bright but hygroscopic scintillator materials that are widely used in X‐ray imaging and detectors. Precipitating them in situ in glass to form glass ceramics (GCs) scintillator offers an efficient avenue for large‐scale preparation, high spatial resolution, and excellent stability. However, precipitating a high fraction of metal halide nanocrystals in glass to maintain high light yield remains a challenge. Herein, an ionic‐covalent hybrid network strategy for constructing GCs scintillator with high crystallinity (up to ≈37%) of BaCl2: Eu2+ nanocrystals is presented. Experimental data and simulations of glass structure reveal that the Ba2+‐Cl− clustering promotes the high crystallization of BaCl2 nanocrystals. The ultralow phonon energy (≈200 cm−1) of BaCl2 nanocrystals and good Eu reduction effect enable high photoluminescence inter quantum efficiency (≈80.41%) in GC. GCs with varied crystallinity of BaCl2: Eu2+ nanocrystals demonstrate efficient radioluminescence and tunable scintillator performance. They either outperform Bi4Ge3O14 single crystal by over 132% steady‐state light yield or provide impressive X‐ray imaging resolutions of 20 lp mm−1. These findings provide a new design strategy for developing bright transparent GCs scintillators with a high fraction of metal halide nanocrystals for X‐ray high‐resolution imaging applications.

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Ionic to covalent glass network transition: Effects on elastic and vibrational properties according to ultrasonic echography and Raman spectroscopy

Cited by 24 publications

References 32 publications

Deconvoluting interrelationships between low‐energy vibrational modes and elastic properties in CaO–Al₂O₃ glasses

Deconvoluting interrelationships between low‐energy vibrational modes and elastic properties in CaO–Al₂O₃ glasses

Molecular relaxation dynamics and self-association of dexamethasone sodium phosphate solutions

Bright Transparent Scintillators with High Fraction BaCl₂: Eu²⁺ Nanocrystals Precipitation: An Ionic‐Covalent Hybrid Network Strategy toward Superior X‐Ray Imaging Glass‐Ceramics

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Ionic to covalent glass network transition: Effects on elastic and vibrational properties according to ultrasonic echography and Raman spectroscopy

Cited by 24 publications

References 32 publications

Deconvoluting interrelationships between low‐energy vibrational modes and elastic properties in CaO–Al2O3 glasses

Deconvoluting interrelationships between low‐energy vibrational modes and elastic properties in CaO–Al2O3 glasses

Molecular relaxation dynamics and self-association of dexamethasone sodium phosphate solutions

Bright Transparent Scintillators with High Fraction BaCl2: Eu2+ Nanocrystals Precipitation: An Ionic‐Covalent Hybrid Network Strategy toward Superior X‐Ray Imaging Glass‐Ceramics

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Product

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Deconvoluting interrelationships between low‐energy vibrational modes and elastic properties in CaO–Al₂O₃ glasses

Deconvoluting interrelationships between low‐energy vibrational modes and elastic properties in CaO–Al₂O₃ glasses

Bright Transparent Scintillators with High Fraction BaCl₂: Eu²⁺ Nanocrystals Precipitation: An Ionic‐Covalent Hybrid Network Strategy toward Superior X‐Ray Imaging Glass‐Ceramics