Quantitative analysis of elastic moduli of tellurite glasses
- PDF / 351,590 Bytes
- 5 Pages / 593.28 x 841.68 pts Page_size
- 104 Downloads / 284 Views
I. INTRODUCTION Recently, much experimental and theoretical work has been performed on the elastic moduli of tellurite and phosphate glasses.1"6 Due to the limitation of phosphate glasses, tellurite glasses are of technical interest. The elastic moduli of tellurite glasses have been measured as a function of both temperature and pressure.1"3 The results indicated that these glasses were normal in their behavior, in contrast to silica-based glasses which have anomalous behavior. Because the coordination number seems to be the parameter which determines the elastic characteristics of glasses, the objective of the present work is to calculate and analyze the elastic moduli of our glasses according to the average crosslink density of each glass system. The important physical properties of each glass system and the method of measuring the elastic moduli by means of determining the ultrasonic wave velocity (longitudinal and shear) are in Ref. 1. The method of glass preparation, including melting and annealing points, and the notation for
every glass system is as used before in Ref. 1, as shown in Table I. II. ELASTIC MODULI OF THE POLYCOMPONENT OXIDE GLASS The bulk modulus of a polycomponent oxide glass of the formula xAmlOni - yBm2On2 - (1 - x - y)GnOm (where G is the glass-forming cation, A, B are the added cation and x, v are mole fractions) has been calculated from the formula suggested in Refs. 3-6. The bulk modulus on this bond compression model is given by — S
(1)
Kbc = nbr2f/9
(2)
nb = «/NAp/M
(3)
where Kbc is the calculated bulk modulus according to the bond compression model, S is the structure factor,
TABLE I. Glass composition and notation of binary, ternary, and quaternary systems.1 Glass
Glass formula
1 —Binary Lanthanum tellurite Cerium tellurite Samarium tellurite
Notation
(La203)o.i(Te02)o.9 (Ce02)o.i(Te02)o.9 (Sm203)o.i(Te02)0.9
A B C
(Er203)o.i(W03)o.3(Te02)o.6 (Y203)o.03(W03)o.2(Te02)o.77 (La203)o.o3(W03)0.2(Te02)0.77 (Sm203)o.o5(W03)o.2(Te02)0.75 (Ce02)o.o5(W03)o.2,(Te02)o.74
D E F G H
2—Ternary Erbium tungsten tellurite Yttrium tungsten tellurite Lanthanum tungsten tellurite Samarium tungsten tellurite Cerium tungsten tellurite 3 —Quaternary Erbium tungsten lead tellurite
2218
http://journals.cambridge.org
(Er203)o.02(W03)().29(PbO)o.2(Te02)o.«
J. Mater. Res., Vol. 5, No. 10, Oct 1990
Downloaded: 16 Feb 2015
© 1990 Materials Research Society
IP address: 130.179.16.201
R. El-Mallawany: Quantitative analysis of elastic moduli of tellurite glasses
Kd is the final estimated bulk modulus, nb is the number of network bonds per unit volume, r is the bond length, and/is the first order stretching force constant. Finally, nf is the number of network bonds per formula unit, NA is Avogadro's number, p is the density, and M is the molecular weight of the glass, respectively. The Poisson's ratio is calculated after obtaining the average crosslink density, which was suggested in Ref. 4, according to the formula dd = const.(nc)"1/4 (4) nc = [(/icMAkW'7 (5) where nc is the average crosslin
Data Loading...
