Infrared absorption spectra of gamma irradiated glasses of the system Li20-B2o3-Al2o3

Spectroscopic studies on alkali metal borate glasses have revealed that the structure of alkali metal borate glasses is dependent not only upon the content of the alkali metal ion but also upon the difference in the alkali metal ion [1] Basic characteristics of borate glass structures are generally agreed upon. The fundamental building block in vitreous B[2]O[3]- is the BO[3] groups either as a random network of boroxol rings beside some fraction of BO[3] triangles [2] connected by B-O-B linkages [bridging atoms][2] The boroxol group is composed of three corner-sharing BO[3] triangles which form a very highly planar ring. Recent studies concluded that any model which attempts to give a full description of the structure of B[2]O[3] must include a high concentration of boroxol group. The addition of alkali oxides modifies the boroxol rings; complex borate groups with one or two four-coordinated boron atoms are formed[4]. Alkali oxide is usually incorporated into B[2]O[3] glass ionically. The initial effect upon the introduction of alkali oxide into B[2]O[3] is the conversion of Sp [2] planar BO[3] units into more stable Sp3 tetrahedral BO[4]. units thereby preserving the B-O bonding without the creation of non bridging oxygen [NBO] ions. Early NMR studies [5] indicated that the conversion of 3-to-4 coordinated boron extends for levels of alkali oxide up to about 30 mol percent and that the NBO ions should be created in large numbers at alkali oxide concentrations above the 30 mol percent level The alkali borate glasses will be composed of structural groupings [boroxol, tetraborate, diborate, metaborate, pyroborate, and orthoborate] present in the various crystal structures of the alkali borate compounds. The abundance and type of structural units present depend upon the amount of alkali oxide incorporated into the glass. Detailed recent investigations of the infrared spectra of borate glasses and their corresponding crystalline derivatives have been carried by Kamitsos et al[6]'. The interpretation of the results is believed to be tough task, due to the complexity originating from the glassy nature of the materials and to the large number of possible structural groups found in borate glasses. In a previous investigation [7] the effect of progressive increasing gamma rays dose on the infrared spectra of ternary borosilicate glasses of the system BaO-B[2]O[3]-SiO[2] was studied Experimental results indicate that the intensities of the characteristic absorption bands generally decrease with radiation, the frequencies of all the observed bands remain unchanged, and new bands are formed. In this paper, the work is continued to make a vibrational analysis by comparing the spectra obtained before and after gamma-ray irradiation to search for a further support to the previous published work and emphasizing to the role of changing glass composition on the infrared spectra of the. ternary Li[2]O-B[2]O[3]-Al[2]O[3] glasses

Behaviour of ultrasonic in chromium doped xpb0- [100-x] b2o3 glasses

Glasses containing lead oxide are extensively used for various purposes. In addition to the conventional industrial applications, such as crystal glass and optical glasses, low-melting glasses and glass-ceramics have been widely used in the field of electronic technology. Lead-borate glasses doped with transition metal ions have gained greater importance in various fields [1,2] The potential applications are attributed to their conductivity, thermal stability, chemical durability etc. of the glass system. The added alkali oxide is usually incorporated into borate glass ionically, resulting in the change of boron coordination from three to four and after certain limit leads to the formation of non-bridging oxygen [NBO]. The compositional dependence of lead-borate glasses doped with transitional metal oxides have been studied [3-5] through electrical, optical and physical properties. Recently, Bishnol et al [6] studied the electrical and optical properties of Cr [3+] doped chlorophosphate and phosphate glasses. However, acoustical measurement, which is an important tool to study the structure and properties of glass network, has been found to be scanty in the present high lead glass system. The study of acoustical properties with the addition of chromium on lead-borate glasses is significant not only due to their technical importance, but also for better understanding of the glass network. The composition dependence of elastic constant, various acoustic and the derived parameters have been made on silicate glass systems [7-10]. In our laboratory recently we have reported the effect of the influence of acoustical parameters on chromium doped sodium-silicate glasses [11] in continuation, in the present investigation an attempt has been made to analyse the influence of various acoustical parameters, on the structure and properties of chromium doped lead-borate XPbO-[100-X] B[2]O[3] + 0.05 Cr[2]O[3] glasses with different composition of X and chromium. Further, the effect of replacement of lead oxide [PbO] by a monovalent ion, namely Na[+], in the chromium doped lead-borate glasses have also been studied from the measured ultrasonic velocity, attenuation, density and the derived parameters. The following parameters namely longitudinal modulus [L], acoustic impedance [Z] and Internal friction [Q[-1]] have been calculated from the measured data. The composition dependence of these parameters has been discussed with effect of change in structure of glass network with change in composition of alkali oxide, Chromium and the introduction of a monovalent ion in the place of PbO

Chemical durability of some glasses in hydrochloric acid solution

Chemical durability of some sodium silicate and sodium boro-silicate glasses in 0.1 M hydrochloric acid solution was studied. The raw materials used were all of chemically pure grade and were finely pulverized. All melts were made in Pt-2% Rh crucibles in electric furnaces. The temperature of melting ranged from 1400 to 1500 degree for 4 hours. After complete melting, the molten glass was annealed at the appropriate temperature, and then the glass was crushed using an agate mortar. All the measurements of the chemical durability of the glass grains [0.3-0.6 mm] for each glass sample, was carried out by the grain method using 0.1 M HCl solution as the immersion solution. The experimental results obtained revealed that the change in the weight loss with the gradual increase of the soda content was attributed to the accepted ionic diffusion mechanism for acidic solution in such glasses. Also, the mixed alkali effect on such behavior was discussed