C. Bootjomchai

Influence of CeO2 on structural properties of glasses by using ultrasonic technique: comparison between the local sand and SiO2.

Comparison between the local sand and SiO2 with different compositions of CeO2 on the structural properties of glasses was carried out by using ultrasonic technique. The ultrasonic velocities were measured by the pulse echo technique with a frequency of 4 MHz and at room temperature. From these obtained velocities and densities, various elastic moduli, micro-hardness and Poissons ratio were calculated. The interesting point of the bulk modulus (SiO2 glass system) decreases at x = 1.25 mol.% initially before it turns to increase between x = 3.75 and x = 5.00 mol.%. While the bulk modulus of the local sand glass system is near constant. FTIR spectra were used to study the structural properties of the prepared glass system. The results supported our discussion of the formation of non-bridging oxygens (NBO) and bridging oxygens (BO).

Structural investigation of glasses with doped some transition metal oxides under the influence of gamma irradiation

The ultrasonic velocity of the alkali-borosilicate with different transition metal oxides (TMO) has been studied using the pulse echo technique. The elastic moduli such as elastic constant and bulk modulus have been obtained from the experimental data. Changes in the structure with different gamma irradiation doses have been investigated by using FTIR spectroscopy and ultrasonic studies. The results show that structural changes in the BO3 to BO4 due to TMO and irradiation are obtained.

Comparative studies of glow peaks and kinetic trapping parameters of LiF(Mg,Cu), LiF(Mg,Cu,P), LiF(Mg,Cu,Si) and LiF(Mg,Cu,Na,Si) single crystals

Glow curve structure and kinetic trapping parameter of the thermoluminescent (TL) phosphors based on LiF(Mg,Cu) LiF(Mg,Cu,P) LiF(Mg,Cu,Si) and LiF(Mg,Cu,Na,Si) single crystals were investigated (denoted as SMC, SMCP, SMCS and SMCNS, respectively). Wet mixing and drying before TL phosphors production in single-crystal form were achieved by the Bridgeman method. The transparent solid single crystals were cut to the size of 5.0×5.0×0.6 mm3 for use as thermoluminescence dosimeters (TLD). Four different types of TLD were irradiated with X-ray photon energy 128 keV in the dose of 3 mGy after dual step pre-irradiation annealing. From the glow curve structure, the geometrical factors (μ) were calculated. The graph created by Chen confirms the first-order kinetics. Moreover, the glow curve shape results in more fading of the TLD 100 sample than the SMCS and SMCNS samples. It is evident that the kinetic trapping parameters depend on the type of dopant. The frequency factors of all TLD single crystals are higher than TLD100 (poly-crystal). These results are useful to provide the TL trapping and recombination centers for these materials.

Structural investigations of bismuth lead borosilicate glasses under the influence of gamma irradiation through ultrasonic studies

The ultrasonic velocity measurements for different compositions of irradiated bismuth lead borosilicate glasses xBi2O3–(50–x)PbO–20B2O3–30SiO2 (x=2, 4, 6, 8, and 10 mol.%) were performed at room temperature using pulse-echo technique. Densities of glass samples were measured by Archimedes’ principle using n-hexane as the immersion liquid. The results from the studies show that ultrasonic velocity, elastic moduli, Poissons ratio, microhardness, and the Debye temperature increase with increasing bismuth oxide content and increasing gamma-radiation dose (3–12 Gy).

Characterization of elastic and structural properties of alkali-borosilicate glasses doped with vanadium oxide using ultrasonic technique

Longitudinal and shear wave velocities were measured in borosilicate glasses containing V2O5 using the pulse echo technique. Measurements were carried out at 4 MHz frequency and at room temperature. The density was measured by the conventional Archimedes method. Elastic moduli and some other physical parameters such as Debye temperature and softening temperature were calculated. Results indicated that these parameters depend upon the V2O5 content in glass composition.