Local Structure of Amorphous (PbO)_x[(B₂O₃)_1-z(Al₂O₃)_z]_y(SiO₂)_y Dielectric Materials by Multinuclear Solid State NMR

Abstract

Structural speciation of glasses in the systems PbO-B 2 O 3 -SiO 2 , PbO-B 2 O 3 -Al 2 O 3 -SiO 2 , and PbO-Al 2 O 3 -SiO 2 were studied using solid state 29 Si, 27 Al, 11 B, and 207 Pb nuclear magnetic resonance (NMR) and Raman spectroscopy. Application of these methods provided insight into the role of Al 2 O 3 incorporation in the lead borosilicate glass networks. The general composition range studied was (PbO) x [(B 2 O 3 ) 1-z (Al 2 O 3 ) z ] y (SiO 2 ) y where x ) 0.35, 0.5, and 0.65, y ) (1x)/2 and z ) 0.0, 0.5, and 1.0. Additional insight was obtained via 27 Al 2D-3QMAS experiments. The 207 Pb spin-echo mapping spectra showed a transition from ionic (Pb 2+ ) to covalently bound lead species with increased PbO contents in the borosilicate glasses. The addition of aluminum to the glass network further enhanced the lead species transition, resulting in a higher relative amount of covalent lead bonding in the high PbO content aluminoborosilicate glass. The number of BO 4 units present in the 11 B MAS NMR decreased with increasing PbO contents for both the borosilicate and the alumino-borosilicate glass systems, with the addition of aluminum further promoting the BO 3 species. A deshielding of the 11 B chemical shifts and the 27 Al chemical shifts with increased lead contents (independent of changes in the quadrupolar coupling) was also observed for both glass systems and was attributed to an increasingly homogeneous glass structure. The 29 Si spectra of the borosilicate and alumino-borosilicate glasses showed a downfield shift with increased PbO concentrations representing incorporation of Pb into the silicate and aluminosilicate networks. The Raman spectra were characterized by increased intensities of Si-O-Pb peaks and decreased intensities of Q 3 peaks with increased PbO contents and showed no evidence of BO 3 or BO 4 ring species. Both the NMR and the Raman data point toward systems where lead is increasingly incorporated into the B 2 O 3 -SiO 2 and the B 2 O 3 -SiO 2 -Al 2 O 3 networks at high PbO concentrations, with the addition of Al 2 O 3 enhancing the trend.

The effect of boron oxide on the crystallization behavior of MgAl2O4 spinel phase during the cooling of the CaO-SiO2-10 mass.% MgO-30 mass.%Al2O3 systems

“…3, the R C value decreases as the viscosity of the oxide melts increases. In the present systems, because the T L value continuously decreases with an increase in the boron oxide content, as shown in Figs [26][27][28], affecting the degree of (de)polymerization and the viscosity of the oxide melts. This can be revealed not only by measuring the viscosity of the oxide melts directly but employing a spectroscopic methodology such as Raman spectroscopy for glass systems when they are rapidly quenched.…”

Structural influence of PbO by means of FTIR and acoustics on calcium alumino-borosilicate glass system

“…It can be used as wall-covering panels, floors and roofs in building, interior facing of containers and as a road surfacing [9]. On the other hand, lead borosilicate glasses have some remarkable features such as its high chemically stability over a wide range of concentrations, possess low melting points, a desirable electrical resistivity, and are considered as a basis for the manufacture of various coatings, semiconductor microelectronics, optical lenses, enamels, solder glasses, glass-ceramic cements, and as hard nuclear waste materials [10][11][12][13].…”

Semi-quantitative analysis for FTIR spectra of Al2O3-PbO-B2O3-SiO2 glasses

“…This is observed by Sawvel et al [10], Petrovskaya et al [48] and earlier by Arora et al [9]. They reported that at low content of PbO (≤40 mol.%) it acts as a glass modifier and enters the glass as Pb 2 + ions as bonding of lead is strongly ionic, and the cation enter the network in an interstitial manner.…”

“…[4][5][6][7][8]. Lead borosilicate glasses have some remarkable features such as its high chemically stability over a wide range of concentrations, possess low melting points, a desirable electrical resistivity, and are considered as a basis for the manufacture of various coatings, semiconductor microelectronics, optical lenses, enamels, solder glasses, glass-ceramic cements, and as hard nuclear waste materials [1,4,9,10]. Glasses in the system PbO-Al 2 O 3 -B 2 O 3 -SiO 2 have various applications, such as thick film technology ink constituents, mixed oxide dielectrics and host for fluorescence centers in optical devices.…”