Elastic, Electrical and Thermal Properties of Tellurite Glass Systems

Three series of tellurite glass were synthesized by melt quenching technique. The binary tellurite was (TeO2)x (B2O3)1-x with x = 60, 63, 65, 70,73, 75, 78, 80 mol%, the ternary tellurite [(TeO2)x (B2O3)1-x]1-y [Ag2O]y consists of three series that is x = 60, 65 and 70 mol% with y = 10, 15, 20, 25 and 30 mol% and quaternary tellurite glass {[(TeO2)x (B2O3)1-x]1-y [Ag2O]y}1-z {AgI}z with z = 5, 8, 10, 13, 15 mol%. The experimental investigation was divided into two categories. The minor experimental work, which provides supportive evidence to elastic and electrical properties, consists of work on x-ray diffraction, thermal expansion coefficient and optical absorption spectra. The main experiments consist of work on ultrasonic and electrical measurements. The electrical measurements consist of dielectric and ac conductivity properties were measured at low frequencies from 10-2 to 106 Hz while ultrasonic properties were determined with MATEC 8000 at 5MHz resonating frequency and at room temperature. The amorphous structures of the glass samples were evident by the XRD spectrum. Thermal expansion measurement showed that thermal expansion coefficient was composition dependence. The optical absorption spectra of these glasses were measured, the Urbach rule has been applied to evaluate the fundamental absorption edges for all the glasses from the obtained spectrum. The optical band gaps were calculated from the absorption edge and it was found that the optical band gap energy, Eopt depended on the glass composition. The optical band gaps energy showed a decreasing pattern with composition for binary and ternary tellurite glass however it behaves otherwise for quaternary tellurite glasses. Elastic moduli were found dependent on compositions; for binary tellurite system the elastic moduli increased with the increase of TeO2 and for ternary and the quaternary system elastic moduli decreased with Ag2O and AgI respectively. The increase of elastic moduli for binary system was due to the mix former effect and the decreased elastic moduli for ternary was due to Ag2O breaking the bonds of the borotellurite glass system while AgI iodide caused network expansion of the glass structure and weakened the glass structure of this quaternary tellurite system. The Debye temperature and mirohardness had the same trend as the elastic moduli but the Poisson’s ratio always the inverse of the elastic moduli. The results of dielectric response measurements and the results of the equivalent circuit analysis show that electrode polarization at low frequency, orientation polarization at intermediate frequency and polarization of defect glass structure at high frequency are the most probable process responsible for the observed dielectric behaviour of the studied glass samples. The dependence of the alternating current conductivity with frequency at various fixed temperature revealed three distinguishable regions; high frequency dispersion, low frequency dispersion and electrode polarization. The electrical conductivity of tellurite based glass was found to obey the exponential double power law

Ciri Kenyal dan Rawat Haba Bagi Kaca Argentum Borat dan Fosfat

Kaca boleh dihasilkan dalam pelbagai komposisi pada julat yang luas untuk penggunaan tertentu. Dalam kajian ini, kaca argentum dengan pembentuk kaca borat dan fosfat telah dikaji. Empat siri kaca telah berjaya disintisiskan iaitu argentum borat (Ag20)x (B203)J-x (x = 0.2 hingga 0.4), argentum iodida (P205)I-x (x = 0.2 hingga 0.5) dan argentum iodida fosfat (AgI)x [Ag20 2 P205]I-X (x = 0.035 hingga 0.6). Pengukuran halaju ultrasonik telah dijalankan menggunakan sistem pemperolehan data ultrasonik MBS 8000. Ketumpatan kaca tersebut diukur dengan menggunakan prinsip Archimedes. Daripada halaju dan ketumpatan, ciri-ciri kenyal kaca boleh didapafi. Modulus Young, modulus pukal dan suhu Debye didapati meningkat dengan kandungan Ag20 dan mula berkurangan setelah komposisi pecahan mol Ag20 melebihi 0.35 bagi argentum borat . Modulus Young dan modulus pukal bagi argentum iodida borat didapati meningkat dengan penambahan AgI tetapi corak suhu Debye yang berkurangan dengan meningkatnya AgI. Bagi kaca argentum fosfat, modulus Young dan modulus pukal meningkat dengan kandungan Ag20 dan suhu Debye dengan corak berkurangan. Modulus Young didapati meningkat dengan AgI tetapi corak yang berkurangan bagi modulus pukal dan suhu Debye diperhatikan dalam kes argentum iodida fosfat. Ciri-ciri kenyal kaca didapati berkait rapat dengan kekuatan rangkaian dan struktur kaca. Kedua-dua siri kaca didapati mempunyai modulus kenyal semakin meningkat terhadap suhu. Setelah mendapat rawatan haba, diperhatikan bahawa kaca semakin tegar dan struktur kaca semakin kuat

Role of Nd3+ nanoparticles on enhanced optical efficiency in borotellurite glass for optical fiber

The main problem of commercial silicate glass fiber is its high-loss and weak optical efficiency. It is very important to produce non-silicate glass fiber with low-loss and high optical efficiency. In this work, low-loss and high optical efficiency of Nd3+ nanoparticles doped borotellurite glass had been produced. The analysis of FTIR spectra shows the presence of functional vibration of tellurite network. The refractive index of borotellurite glass was enhanced in between 1.947 and 2.045 with the increment of Nd3+ nanoparticles. Several excitation bands within UV–Vis range due to the effect of Nd3+ nanoparticles was perceived originating from the ground state 4I9/2 to the excited states 2P3/2, 4G7/2, 4G5/2, 4F9/2, 4F7/2, 4F5/2 and 4F3/2. The glass system shows tendency towards semiconducting behavior as the value of Fermi energy, EF decreases. The high intensity of red emission was found from Nd3+ nanoparticles doped borotellurite glass. Hence, this Nd3+ nanoparticles doped borotellurite glass has immense potential for the development of fiber amplifiers and lasers

Effects of additives and sintering time on the microstructure of Ni-Zn ferrite and its electrical and magnetic properties

This work aims to investigate the relationship between the microstructure of Ni-Zn ferrite and its electrical and magnetic properties in the presence and absence of as small amounts as 0.12% of 0.4CaO + 0.8SiO2 over different sintering times. The X-ray diffraction pattern showed a single spinel phase formation in all the samples. The results indicate that grain growth occurred by increasing sintering time from 15 to 270 min in the two types of samples prepared in this study although it was greatly impeded by the additive oxides. Moreover, the oxides increase the resistivity of the ferrite and decrease its zinc loss. Magnetic properties such as induction magnetization (BS) and saturation magnetization (MS) decreased in the presence of the additives while its coercivity (HC) increased. Finally, the density of the samples was observed to increase with increasing sintering time in both types of the samples but with a higher value in the samples with no additives

Dielectric and electrical characteristics of mechanically synthesized Ni-Zn ferrite nanoparticles

Ni-Zn ferrite nanoparticles were synthesized via mechanical activation of Zn, NiO and Fe2O3 powders in a high energy planetary ball mill. The 30 h-milled samples in argon, oxygen and air atmospheres were pressed in pellet and toroid shape form and were sintered from 500 °C to 900 °C with 100 °C increments. The X-ray diffraction patterns results indicated a single phase Ni-Zn ferrite formation with a cubic-spinel structure in all the samples sintered at 500 °C. The milling atmosphere had a key role in the synthesis, microstructure and properties of the samples in such a way that this effect sustained even after the completion of sintering process. Thus, the main goal of this study is to scrutinize the effect of sintering temperature in the 30-h-milled samples in different atmospheres on DC electrical resistivity and dielectric behavior of Ni-Zn ferrite samples. The results indicated that although electrical resistivity decreased, dielectric behaviors, i.e. constant, loss and tan increased with increase in sintering temperature. The milled samples in argon had the highest resistivity of 1.2 106 Ωcm at 500 °C, and lowest dielectric constant and loss (4.67 102 and 1.7 at 300 K and frequency 106 MHz, respectively) compared to other samples owing to more homogeneity and smaller average crystallite size, making them a good candidate for high frequency applications. X-ray photoelectron spectroscopy (XPS) revealed the presence of metal ions in their proper valence in the Ni-Zn ferrite crystal structure. Noticeably, a variation in the binding energy for the milled samples in different atmospheres is attributed to the changes in surroundings of Fe3+ and Zn2+/or Ni2+, due to non-equilibrium distribution of cations in tetrahedral and octahedral sites, which is further confirmed by the XRD patterns

Numerical method for computing Maass cusp forms on triply punctured two-sphere

A quantum mechanical system on a punctured surface modeled on hyperbolic space has always been an important subject of research in mathematics and physics. This corresponding quantum system is governed by the Schrödinger equation whose solutions are the Maass waveforms. Spectral studies on these Maass waveforms are known to contain both continuous and discrete eigenvalues. The discrete eigenfunctions are usually called the Maass Cusp Forms (MCF) where their discrete eigenvalues are not known analytically. We introduce a numerical method based on Hejhal and Then algorithm using GridMathematica for computing MCF on a punctured surface with three cusps namely the triply punctured two-sphere. We also report on a pullback algorithm for the punctured surface and a point locater algorithm to facilitate the complete pullback which are essential parts of the main algorithm

Comprehensive study on the effect of Gd2O3 NPs on elastic properties of zinc borotellurite glass system using non-destructive ultrasonic technique

Quaternary Gd2O3 NPs doped zinc borotellurite (TeO2-B2O3-ZnO-Gd2O3 NPs) glass system were fabricated using conventional melt-quenching method with composition {[(TeO2)70(B2O3)30]70(ZnO)30}1-x(Gd2O3 NPs)x (x = 1.0, 2.0, 3.0, 4.0 and 5.0 mol%). The physical, structural and elastic properties of the glass samples were investigated. X-ray diffraction (XRD) were used to confirm the amorphousity of the samples. Fourier Transform Infrared (FTIR) spectroscopy indicated the presence of TeO3, TeO4, BO3 and BO4 structural units within the glass matrix. The presence of Gd2O3 NPs was proven from Transmission Electron Microscopy (TEM). The density and molar volume showed anomalous behavior. The elastic properties of the glass system were characterized by using pulse-echo technique. The longitudinal and shear ultrasonic velocities vary from 3883 to 4042 m/s and 2265 to 2282 m/s, respectively. The observed change in the ultrasonic velocities imply that there are substantial change in the structure of the vitreous network. The experimental elastic moduli (longitudinal modulus (L), shear modulus (G), bulk modulus (K) and Young's modulus (E)) increases from 68.77 to 79.45 GPa, 23.40 to 26.68 GPa, 37.56 to 48.25 GPa and 58.13 to 66.55 GPa, respectively. The increase in elastic moduli of the glass system indicates that the strength and rigidity of the glass increase. The experimental elastic moduli were correlated and compared with the theoretically calculated elastic moduli using Makishima-Mackenzie and Bond Compression model

Optical properties of erbium doped borotellurite glass system

Erbium doped zinc borotellurite glasses were prepared by using melt-quenching method. The structural properties of the glass samples were determined by using x-ray diffraction (XRD) method and was confirmed its amorphous nature. The density and molar volume is shown to be increased with increasing content of erbium. The refractive index is found to be increased with increasing content of erbium

Effect of lanthanum oxide on optical properties of zinc borotellurite glass system

A series of zinc borotellurite glasses doped with lanthanum oxide with the chemical composition {[(TeO2)0.70(B2O3)0.30]0.7(ZnO)0.30}1-x (La2O3)x where x = 0.01, 0.02, 0.03, 0.04, and 0.05 molar fraction have been fabricated using conventional melt-quenching method. The structural properties of the fabricated glass samples were determined by X-ray diffraction (XRD) analysis and Fourier Transform Infrared (FTIR) analysis. XRD result confirmed that the fabricated glasses are amorphous. Density and molar volume of the prepared samples were measured and calculated. The optical properties of the prepared glasses were determined by UV-Vis analysis. The optical absorption spectra reported that the fundamental absorption edge shifts to lower wavelength as the amount of La2O3 increases. The refractive index, direct optical energy band gap, indirect optical energy band gap and Urbach energy had been calculated and analyzed

Determination of thermal diffusivity polypyrrole and polypyrrole/bismuth oxide conducting polymers using laser flash technique

The determination of conducting polymer’s thermal properties is essential in engineering processes and design. Thermal diffusivity is one of the important thermal properties in non-steady state situations. This fundamental knowledge is useful in the development of processes and control, selection of materials and prediction of end use properties in many engineering process and design. In this research, laser flash technique is employed to determine the thermal diffusivity of Polypyrrole and Polypyrrole/Bismuth Oxide conducting polymers. Measurements were carried out from room temperature up to 420 K. It was observed that the presence of secondary doping agent of bismuth oxide enhanced the thermal properties of polypyrrole conducting polymer