Glasses In Li2O Research Articles

Lithium ion conducting glasses in the system LiClLi 2OP 2O 5SiO 2

Glasses with good ionic conductivity of lithium ions have been prepared in the LiClLi 2OSiO 2P 2O 5 system. The SiO 2/P 2O 5 ratio was kept at 1 5 and it was found that below 1200°C, this leads to a Li 2O/P 2O 5 ratio of about two for the glasses formed. The structure of the glasses appears to be composed of linear chains of phosphate polymers. The highest ionic conductivity is observed in the composition 0.25LiCl0.48Li 2O0.03SiO 20.24P 2O 5 with σ = 2.5 × 10 −3 (Ω-cm) −1 and E a = 0.54 eV (52 kJ/mol) at 235°C. The conductivity increases, the activation energy and the glass transition temperature decrease with increasing LiCl content. Results of the ionic conductivity, FTIR, and DSC measurements are discussed in terms of composition and structural properties of the chloride glasses, and are compared with those of the corresponding oxide glasses.

RAMAN SPECTRA OF GLASSES IN THE Li2O-(LiCl)2-B2O3-Al2O3 SYSTEM

In this paper, the structure of glasses in Li2O(LiCl)2B2O3-Al2O3 system, particularly the influence of Al2O3, is investigated by Raman spectra. For Li2O-B2O3 glasses, with increasing Li2O content, triangular BO3 units change into BO4 tetrahedra and borate groups containing more BO4 are formed. When Li2O content is greater than 35 mol% the metaborate groups begin to form. By replacing B2O3 with Al2O3, the Al3+ ions introduced in glasses take the four-coordination, and AlO4 tetrahedra replace BO4 tetrahedra under the condition of existing sufficient Li2O. However, when Al2O3/Li2O ratio is close to or even greater than unity, part of Al3+ ions are no more in the four-coordination. The experiment also indicates that Raman spectra only depends upon the O/B/Al ratio, showing that the LiCI molecules introduced into the glass are dissociated by glass network. These results can be used to interprete the variations of ionic conductivity with composition.

ACOUSTIC PROPERTIES OF GLASSES IN Li2O-(LiCl)2-B2O3-A12O3 SYSTEM

The densities and supersonic velocities were measured and the adiabatic compressibilities were calculated for several series of glasses in Li2O-(LiCl)2-B2O3-Al2O3 system. The changes of structures of glass networks with compositions were analyzed according to their acoustic properties. These provided a method and basis of analysis for our study of the ionic conduction of glasses.

X-ray diffraction study of glasses in the system Li2O–SiO2

X-ray diffraction patterns have been obtained from Li2O·xSiO2 glasses (x=2, 3, 4). By the Fourier analysis the radial distribution function was evaluated, from which interatomic distance and coordination number were obtained. Their values were compared with those of silica glass and of Li2O·2SiO2 crystal. In Li2O·2SiO2 glass (one phase), the distance of Si–O, O–O and Si–Si was 1.62, 2.65 and 3. 07A, respectively. That is, the structure of short range order of Li2O·2SiO2 glass was almost similar to that of Li2O·2SiO2 crystal. In Li2O·4SiO2 glass, which undergoes phase separation and is composed of SiO2-rich phase and Li2O·2SiO2-rich phase, the fifth peaks in the radial distribution curve were found at about 4.8A and 5.1A. And the radial distribution curve of Li2O·3SiO2, which undergoes slight phase separation, indicated the intermediate value between Li2O·2SiO2 glass and Li2O·4SiO2 glass.