Search

The effect of various binding agents based on aqueous solutions of nitric acid, yttrium nitrate and orthophosphoric acid and yttrium hydroxide gel on the physical and mechanical properties of casting molds based on Y2O3 has been studied. It is shown that the most promising binding agent for yttrium oxide casting molds is a phosphate bond. The data describing the curing mechanism of phosphate-bonded molding mass is presented. The influence of the concentration of binding agent solutions on the strength characteristics of molding materials after curing and heat treatment is shown. Information about the interaction of yttrium oxide powder molds with phosphate-binding with titanium melt of VT1-0 and VT6 grades is presented. The obtained data allowed us to describe the advantages and disadvantages of the developed molding compound. A method for producing casting molds based on yttrium oxide powder with a yttrium phosphate-binding agent was developed based on this research.

The simulation-based artificial neural networks (ANN) program is one of the suitable candidates from artificial intelligence simulation which can work to predict important ultrasonic and mechanical parameters in the glass field. This research is focused on exploring the validity of this system by comparing the prediction values from ANN with the experimental measurements and other theoretical models. The ANN simulation was effectively applied to a binary zinc-borate glass system with the composition of zZnO−(100-z)B2O3 where z = 0, 40, 45, 50, 55, and 60 mol%, which was fabricated by using the melt-quenching techniques. The increase of ZnO content caused the ultrasonic velocity and elastic moduli of the glasses to exhibit a decreasing trend. The bond compression theoretical calculation compared with the experimental measurement was considered to be satisfactory with the value of the coefficient R2 being around 0.92452 to 0.98492. The Makishima-Mackenzie calculation model concerning the experimental measurement of the elastic moduli and Poisson's ratio were between 0.86628 to 0.99786. The coefficient R2 value from the ANN simulation displayed on the density, ultrasonic velocity, and elastic moduli graph is around 0.9999 to 1.0000, which is considered to be very reasonable. The values predicted by this remarkable model proved that ANN simulation is suitable for use in glass research.

In this research, the study of two dopants, strontium oxide and manganese oxide were thoroughly investigated based on the elastic properties for the purpose of high strength glass application. The melt quenching technique method was used to synthesize two series of borotellurite glass systems doped with manganese and strontium. Elastic measurement, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the prepared glass samples. The increment of molar volume confirmed the theory that molar volume is inversely proportional to the density parameters. A broad hump was observed during XRD as the samples shows pure amorphous nature. In FTIR, the vibrations of the functional group of the tellurite network were recorded such as TeO4 trigonal bipyramids and TeO3 trigonal pyramids, by addition of both dopants. On the other hand, ultrasonic velocity was used to determine the elastic moduli of the glass such as bulk modulus, shear modulus, longitudinal modulus, Young’s Modulus, microhardness and Poisson’s ratio which showed decreasing and increasing trends with the increased concentration of MnO2 and SrO respectively. It is also inferred that strontium oxide has better elastic properties than manganese oxide.

Kaolinite clays can serve as an additional source of alumina in the Republic of Kazakhstan. The most promising is the Alekseevsky kaolinite deposit. To obtain high-quality kaolinite and quartzite products, it is necessary to develop special enrichment techniques, since no satisfactory results were achieved when using standard methods of gravitational enrichment of kaolinites. The paper presents the results of studies of the effect of preliminary chemical activation during the processing of kaolinite clays of the Alekseevsky deposit. Previously, the method of preliminary chemical activation of raw materials in a solution of sodium bicarbonate has proven itself well in the processing of various mineral raw materials. It was determined that during the preliminary chemical activation in a solution of sodium bicarbonate, changes occurred in the phase composition of the kaolinite fraction: the content of muscovite decreased almost twice; the phase of sodium aluminosilicate was formed. The dependence of the yield of Al2O3 in the kaolinite fraction on the temperature of chemical activation, duration, and the ratio of L:S and the concentration of the sodium bicarbonate solution during chemical activation. The optimal mode of preliminary chemical activation of kaolinite clay of the Alekseevsky deposit has been established: the temperature is 150 oC, the duration is 120 minutes and the concentration of sodium bicarbonate solution is 120 g/dm3. A basic technological scheme is proposed for the processing of kaolinite clays.

This work presents the effect of erbium oxide in tellurite glass on the intensity parameters, emission and upconversion to be used as laser glass. We select 0.04 mol fraction of erbium oxide in tellurite glass as it gives the optimum results for glass stability, luminescence and intensity parameters. The structural arrangement of glass matrices was revealed by XRD analysis. The amorphous structural arrangement was found and there was no crystalline structure existed in the glass matrix. The FTIR analysis revealed the existence of TeO3 non-bridging oxygen which has important role in the shifting of the optical parameters. The Judd–Ofelt analysis (intensity parameters, Ωλ = 2, 4, 6) were studied by applying nine transition states obtained from UV–Vis-NIR absorption spectrum which were 4G11/2 + 2H9/2 + 4F5/2 + 4F7/2 + 2H11/2 + 4S3/2 + 4F9/2 + 4I9/2 + 4I11/2. The obtained results for the intensity parameters were in accordance by the following trends Ω2 > Ω4 > Ω6. A broad red emission at 648 nm was found with excitation state of 380 nm. Four emission peaks were found from upconversion emission spectrum as follows; 381 nm, 420 nm, 466 nm and 560 nm which correspond to 4G11/2 → 4I15/2, 4F3/2 → 4I15/2, 4F7/2 → 4I15/2 and 4S3/2 → 4I15/2. The prominent emission for upconversion was 560 nm which produce yellow emission. Based on these results, erbium doped boro-tellurite glass is capable to be utilized as red, blue and green glass lasers. The absorption and emission cross sections and optical gain factor have been carried out by using Mc-Cumber theory.

A system of bio-silica borotellurite glasses was fabricated based on the chemical formula [(TeO2)0.7 (B2O3)0.3]1-x (SiO2)x with x = 0.1, 0.2, 0.3, and 0.4 using the melt-quenching technique using silica (98.548% SiO2, from rice husk), TeO2 (Alfar Aeser, 99.9%) and B2O3 (Alfar Aeser, 99.9%). Measurements and characterizations such as density and molar volume measurements, XRD analysis, FTIR, and UV–Vis spectroscopes were performed on the studied glasses. The objective was to determine the glasses’ applicability in optoelectronics, non-linear optics, and laser technologies through polarizability, linear electric susceptibility, and optical basicity study. Apart from confirming the amorphous nature of the glasses, the XRD analysis identified the presence of a crystalline phase of tellurium oxide (α-TeO2) formed. The FTIR spectral study revealed the presence of TeO3, BO3, and SiO4 structural units in the studied glasses. The refractive index (2.3026 – 2.2651), molar polarizability (8.0696 – 9.4334 A3), oxide ion polarizability (3.2970 – 3.6202 A3), electronic polarizability (0.2296 – 0.2335 A3), dielectric constant (5.1307 – 5.3019), optical basicity (0.6719 – 0.7998), metallization criterion (0.410853 – 0.420714) and electric susceptibility (0.3286 – 0.3422 esu) of the glasses were presented. With the high refractive index and favourable electronic/oxide ion polarizability as well as good electric susceptibility, the glasses have shown great potential for optical fibre and laser applications. Metallization criterion value falls in the range of glasses with great potentials for non-linear optical application. The dielectric value suggests the glasses represent wideband semiconducting glasses believed to be good for application in microelectronic substrates fabrication.

Carbon-based materials such as graphene oxide are known as attractive candidate to improve the current optoelectronic and laser devices. In this work, neodymium nanoparticles doped zinc-tellurite glass coated with graphene oxide (GO) denoted as ZBTNd (NPs)-GO was prepared via low-cost melt-quenching method and simple spray coating method. The structural properties of the glass system had been carried out by using X-ray diffraction (XRD) and confirmed its amorphous structural arrangement with non-existence of crystalline structure. The TeO3 and BO3 structural units were found dominant in tellurite glass network as determined by Fourier transforms infrared spectrometer (FTIR). High number of oxygen functional groups and stacked of graphene layers on the glass surface were revealed by field scanning electron microscopy (FESEM) and Raman spectroscopy. The optical band gap energy values were found to decrease in the range of 2.665–2.405 eV along with dopant concentration. In the meantime, the refractive index values were found more than n > 2.00 and fall in the range of 2.12 to 2.20. The electronic polarization was calculated by using Lorentz-Lorentz equation and found in the range of 6.516 to 7.211 A 3. Based on these results, the improvements on optical properties of tellurite glass have been made to be used in laser application.

Rare-earth oxides microparticles doped tellurite-based glass have been studied extensively to improve the capability of optoelectronic devices. We report a detailed comparison between two sets of glass series containing samarium microparticles and nanoparticles denoted as ZBTSm-MPs and ZBTSm-NPs respectively. The two sets of glass have been successfully fabricated via melt-quenching technique with chemical formula {[(TeO2)0.70 (B2O3)0.30]0.7 (ZnO)0.3}1-y (Sm2O3 (MPs/NPs)) y with y = 0.005, 0.01, 0.02, 0.03, 0.04 and 0.05 mol fraction. The TEM analysis confirmed the existence and formation of nanoparticles in ZBTSm-NPs glasses. The density of ZBTSm-NPs glasses was found higher than ZBTSm-MPs glasses due to the distributions of nano-scale particles in tellurite glass network. There was a linear trend of increment in the refractive index in both sets of glass series along with the concentrations of dopants. The refractive index of ZBTSm-NPs glasses was found higher than ZBTSm-MPs glasses due to the shift in compactness of glass structure with nano-scale particles. In comparison, the absorption peaks of ZBTSm-MPs glasses were greater than ZBTSm-NPs glasses which were mainly due to the restriction of electrons mobility in glass network with nano-scale particles. The optical band gap energy in ZBTSm-NPs glasses was found greater than ZBTSm-MPs glasses which correspond to the widening of forbidden gap with nano-scale particles. The polarizability of ZBTSm-NPs and ZBTSm-MPs was found in non-linear trend along with dopant concentrations. Based on these findings, the improvement of optical properties have been made by introducing samarium oxide nanoparticles in tellurite glass which is beneficial for optoelectronic devices.

The process experts are concerned in tellurium due to its various physical and chemical properties. The copper anode slime is the main industrial source of tellurium, after processing of that tellurium becomes marketable product and can be sold both in elemental form and tellurium-containing middling. Physical and chemical properties of the tellurium-containing middling of Kazakhmys Smelting LLP produced in 2018 have been studied in this paper. The following methods have been applied during the study: particle size distribution, X-ray phase, X-ray fluorescence and scanning electron probe microscopy. It was found that material is mainly represented by the large pieces of 0.2 mm in size, with moisture content of 15.57 %, bulk density of 0.8 g/cm3 without tapping and 0.88 g/cm3 with tapping, the angle friction - 33°. The elemental composition of the material was determined by X-ray fluorescence method as follows, wt. %: Cu – 33.327; Te – 21.863; Se – 0.766, O – 35.116; S – 5.045. X-ray phase analysis showed that material is mainly in the amorphous state, the following phases had been identified: Cu2.5SO4(OH)3·2H2O, Cu3(SO4)(OH)4, CuSO4(H2O)3. Tellurium-containing phases could not be detected due to strong amorphism. Hydrosulfate forms of copper in the form of flakes have been found on the surface of the middlings by electron probe microscopy. EDS analysis of individual areas showed that patina also contains small amounts of chlorine, selenium and up to 25 % tellurium, in addition to such elements as copper, sulfur and oxygen. Small amounts of sulfur, chromium, selenium and up to 45 % of oxygen has been found in the open area of material, that is specific for its oxidation.

The study of optical and thermal properties of gadolinium oxide-doped tellurite glass was studied for the first time to the best of our knowledge. Gadolinium oxide-doped tellurite glass system with chemical formula (1 − x)[(TeO2)70(B2O3)30]-x(Gd2O3) with x = 0.2, 0.4, 0.6, 0.8 and 1.0 mol% was prepared by the melt-quenching technique. X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, UV–Vis spectroscopy and EL X-02 high-precision ellipsometer have been carried out. The thermal diffusivity of the amorphous material was studied using laser flash method. The microanalysis of major elements in the glass was examined by employing energy-dispersive X-ray spectrometry. The IR of the glass matrix denotes three obvious absorption bands which are assigned to TeO4, BO3 and BO4 vibrational groups. The addition of Gd ions enhances the refractive index of the tellurite glass. The optical band gap and Urbach energy were determined based on the absorption spectra. It is found that the Gd ions reduce the optical band gap energy. The thermal diffusivity of the glass samples follows nonlinear trend with the concentration of Gd ions. Electronic polarizability, optical basicity and metallization criterion have been calculated for every glass composition. Based on these results, the proposed materials have high potential to be applied in photonic materials.

The melt-quenching method was used to synthesize a series of neodymium-doped zinc tellurite glass systems. The ultrasonic velocities, elastic moduli and other elastic parameters of the prepared glasses showed non-linear variations with an increase of Nd2O3 in the glass system. The non-linear variation is associated with the presence of non-bridging and bridging oxygen caused by the network modifier of Nd2O3. Theoretical data sets for the elastic properties of the glass systems were obtained by using the Makishima and Mackenzie theory and the Rocherulle, bond compression and ring deformation models. The values retrieved for the elastic moduli by using the Makishima and Mackenzie, and Rocherulle models are in great agreement with the corresponding experimental data. The recorded bond compression model data for the glass has much higher values for elastic moduli when compared to the corresponding experimental values. Therefore, in this glass system, only the bond compression model is not favoured.

Copper oxide doped TeO2 – B2O3 glass system with empirical formula; [(B2O3)0.3(TeO2)0.7]1-x(CuO)x using the melt quenching method, where x = 0.0, 0.01, 0.015, 0.02, and 0.025 was combined. The glass samples’ density and molar volume were measured, followed by characterizations using the UV-Vis, Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectroscopes. The amorphous or glassy nature of glass samples was proven by the XRD spectra except for the pure borotellurite sample which showed a peak around 2θ = 20o, indicating α-TeO2 crystalline phase presence. The FTIR spectral analysis suggested the presence of BO3, TeO3 and TeO4 as the structural functional units in the glass samples. The UV-Vis spectra showed no presence of any sharply defined edges, affirming the amorphous or glassy nature of the glass materials. Physical parameters e.g. molar volume, density, oxygen packing density (OPD), inter ionic distance of Cu2+ ions, concentration of copper ion per unit volume (N), as well as the polaron radius data were presented and discussed. Also, the direct bandgap (3.8900 to 3.5900 eV) , indirect bandgap (3.3200 to 3.0800 eV), refractive index (2.318 to 2.378), dielectric constant (5.3731 to 5.6549), optical dielectric constant (4.3731 to 4.6549), refractive index based metallization criterion (0.406885 to 0.391916) and the band gap based metallization criterion (0.407431 to 0.392428) were analysed and discussed. Based on the metallization criterion and values of refractive index, the glasses are good candidates for optoelectronic and laser applications. Meanwhile, the dielectric constants’ values of the present glasses indicate their suitability bandpass filters and microelectronic substrates applications.

The method of preliminary chemical activation of mineral raw materials was used in the conducted studies for the complex processing of pyritic slags. The influence of preliminary chemical activation of kaolinite clays of Alexeevsky deposit in the solution of sodium hydrogen carbonate on the separation of kaolinite and quartz fractions was studied. The temperature of 150 oC, the duration of 120 minutes, and the concentration of sodium bicarbonate solution of 120 g/dm3 should be considered the optimum mode of activation. As a result of activation, the phase composition of the kaolinite fraction changed: the percentage of kaolinite fraction decreased; new phases of muscovite and sodium aluminosilicate appeared; the amount of quartz increased.

New glass samples with composition (1 – x)[(TeO2)70(B2O3)30] – x(Gd2O3) with x = 0.2, 0.4, 0.6, 0.8 and 1.0 in mol% have been synthesized by conventional melt-quenching techniques. X-ray diffraction (XRD) studies were performed in order to confirm the amorphous nature of the samples. The density of the samples has been found to vary with the Gd2O3 content, whereas an opposite trend has been observed in the molar volume. The analysis of Fourier Transform Infrared (FT-IR) spectroscopy of the samples showed that the glass network is mainly built of TeO3, TeO4, BO3 and BO4 units. The addition of Gd2O3 changed the refractive index, optical band gap and Urbach energy of the glass samples. The thermal properties of the studied glasses were investigated by measuring the thermal diffusivity of the samples by using photoflash method at room temperature.

Erbium nano particles (NPs) doped tellurite glasses were prepared via melt-quenched technique and their chemical composition are as follows; {[(TeO2) 0.70 ( B 2 O3) 0.30 ] 0.7 (ZnO) 0.3 } y (Er2O 3 NPs) 1−y , y = 0.005, 0.01, 0.02, 0.03, 0.04 and 0.05. The amorphous state of the glass system was revealed and the structural parameters indicating the formation of non-bridging oxygen was shown. The current work underlines the spectral parameters from Judd–Ofelt (JO) studies, and upconversion spectra. The existence of erbium NPs was found experimentally using transmission electron microscopy (TEM). The Judd–Ofelt analysis suggests that the radiative probability, A rad is strong at 2H 11∕2 —> 4I 15∕2 and a longer lifetime at 4I 11∕2 —> 4I 15∕2 . The Argon laser beam was used to determine the upconversion emission peaks. The upconversion radiation emission excited at 800 nm was found in the range 390 nm.

A system of erbium oxide nanoparticles doped rice-husk-silicate borotellurite glasses with compositional formula, {[(TeO2)0.7 (B2O3)0.3]0.8 (SiO2)0.2}1−y (Er2O3 NPs)y with y = 0.01, 0.02, 0.03, 0.04 and 0.05 was fabricated using the method of melt-quenching. Various characterizations and measurement techniques such as density and molar volume, X-ray diffraction, Fourier transform infrared, transmission electron microscopy and UV–Vis spectroscopy were carried out to study the structural, morphological and optical properties of the fabricated glasses. The density values for the glasses increased from 4.1900 to 4.6003 g cm−3 with the addition of 1% to 5% of Er2O3 NPs in the glass structure. The increase can be ascribed to increase in the overall molar weight of the glass caused by the higher molecular weight of erbium. The microstructural nature revealed in the glass morphological evidence of nanoparticle agglomerations in the glasses. From the UV–Vis spectra both direct and indirect energy band gap decreased with Er2O3 NPs increased 0.01 to 0.02 mol and then increased thereafter up to 0.05 mol%. The refractive index was found to be high, in the range of 2.6050 to 2.6794, metallization criterion ranged from 0.3268 to 0.3414 which according to Berwal et al. (J Mol Struct 1127:636–644, 2017), is an indication that the glass has good optical non-linearity and also suggests the glass has good potential for non-linear optical application. The molar polarizability ranged from 7.7041 to 7.4515 A3 while the optical transmission coefficient values ranged from 0.6551 to 0.6691. The high refractive index, good metallization criterion, polarizability and transmission coefficient values suggest that the erbium oxide nanoparticles doped Rice husk silicate borotellurite glasses studied has some good potential for optical fibre amplifier application.

The use of erbium ions, Er3+ to enhance the dielectric properties is investigated in tellurite glass system for the first time, to the best of our knowledge. A glass series of tellurite glass with chemical composition, {[(TeO2)70(B2O3)30]70(ZnO)30}100−y(Er2O3)y (y = 0, 0.005, 0.01, 0.02, 0.03, 0.04 and 0.05) was fabricated via melt-quenched technique. The X-ray diffraction and Fourier transform infrared spectroscopy analysis proved the amorphous structure and the formation of nonbridging oxygen in the glass system. The Er3+ ions affect greatly to the dielectric constant, e′ in which the dielectric constant, e′ show high value at a lower frequency and higher temperature (above 110 °C). The reduction of dielectric constant, e′ is found with the increment value of frequency, which corresponds to the formation of the hindrance effect on heavy dipoles caused by the mixed transition-ion effect. Meanwhile, the dielectric constant, e′ is enhanced with the increase of temperature. The activation energy of the glass system is found to decrease, which is due to the high polarizability of Er3+ ions in the glass system. Based on these results, the erbium-doped tellurite glass is a potential kind of high-energy capacitor.

This paper presents a study on the structural, morphological and elastic properties of erbium oxide nanoparticles doped bio-silicate borotellurite glass system fabricated using the technique of melt-quenching with chemical compositional formula {[(TeO2)0.7 (B2O3)0.3]0.8 (SiO2)0.2}1−y (Er2O3 NPs)y where 0.01 ≤ y ≤ 0.05. The objective of the work was to study the some elastic and thermal parameters associated with non-destructive ultrasonic technique, with the aim of utilizing the glasses for erbium doped fiber amplifier application. Various measurements and Characterizations techniques which includes density and molar volume measurements, energy dispersive X-ray fluorescence, X-ray diffraction (XRD), Fourier transform infrared (FTIR), Transmission electron microscopy and Pulse-echo technique were carried out in this study. The density values for the glasses increased from 4.1900 to 4.6003 gcm−3 with the addition of 1–5% of Er2O3 NPs in the glass structure. The increase can be ascribed to increase in the overall molar weight of the glass due to incorporation of heavy Er3+ ions. The XRD patterns revealed no presence of sharp peaks with the observed broad hump around 2θ = 20–30° indicating the glassy and amorphous nature of the studied glasses. The FTIR spectra showed absorption with peaks around 1362–1385 cm−1, 1221–1250 cm−1, 655–689 cm−1 and 602–630 cm−1 wave number ranges, indicating the presences of H3BO3, SiO4, BO3, TeO3 and TeO4 structural units in the glass system. The microstructural nature observed in the glass morphology showed nanoparticle agglomerations in the glasses. The ultrasonic velocities, elastic moduli, microhardness, Poisson ratio, softening and Debye’s temperatures, thermal expansion coefficient as well as other important parameters were calculated from the density and ultrasonic data. The values of the ultrasonic velocities, elastic moduli, Debye’s temperature, softening temperature, thermal expansion coefficient and the acoustic impedance increased with increase in the Er2O3 NPs concentration.

Ascertaining plasmonic interaction induced by silver (Ag) and gold (Au) nanoparticles (NPs) in the amorphous system can open a new direction in photonics. In this outlook, various contents of Ag and Au NPs were incorporated into neodymium ions (Nd3+)-doped zinc-sulfate-magnesium-phosphate glasses via the melt-quenching method. The impact of Ag–Au plasmonic coupling on the structures and spectroscopic traits of the prepared glasses were evaluated. As-quenched samples were analyzed using XRD, HRTEM, Raman, absorption and photoluminescence (PL) spectrometer. The Judd-Ofelt (JO) theory was used to evaluate the spectroscopic quality and stimulated emission cross-section of the glasses. HRTEM micrographs verified the existence of Au and Ag NPs in the glass matrix with a mean size ranged 4.47–7.03 nm. The observed thirteen absorption bands centered around 326, 352, 430, 459, 473, 512, 52, 581, 627, 681, 744, 801, and 875 nm were corresponding to electronic transitions from the ground state (4I9/2) to the excited states of 4D7/2, 2D1/2+4D3/2+4D5/2, 2P1/2, 4G11/2, 2D3/2+2P3/2+2G9/2, 4G9/2+2K13/2, 4G7/2, 4G5/2+2G7/2, 2H11/2, 4F9/2, 4F7/2+4S3/2, 4F5/2+2H9/2 and 4F3/2 in Nd3+. Two surface plasmon resonance (SPR) bands assigned to Ag and Au NPs were probed at 442 nm and 503 nm. The addition of Au NPs causes the SPR band of Ag NPs to be red-shifted. The NIR PL bands at 878 nm, 1050 nm and 1322 nm were due to the 4F3/2 → 4I9/2, 4F3/2 → 4I11/2 and 4F3/2 → 4I13/2 transitions, respectively. The PMZ1.5Nd0.5Ag0·1Au glass disclosed the highest bandwidth gain of 6.92, 17.05 and 9.10 ( × 10−23 cm3) corresponding to the 4F3/2 → 4I9/2, 4F3/2 → 4I11/2 and 4F3/2 → 4I13/2 transitions. It was shown that the PL intensity of the studied glasses could be modified by varying Ag and Au NPs contents. The Ag–Au NPs plasmonic coupling inclusion inside the glass can be beneficial to develop versatile optical materials.

In this study, the effect of biscyclopentadienyl magnesium flow rate for the growth of p-type gallium nitride thin films was varied from 20 to 40 standard cubic centimeter per minute to acquire the optimum doping concentration level. The growth of semi-polar (11–22) p-type gallium nitride thin films on m-plane sapphire was accomplished via metal organic chemical vapor deposition. Atomic force microscopy reveals the occurrence of dissimilar grain size distributions upon the utilization of different dopant flow rates. Statistical data shows that the utilization of optimized biscyclopentadienyl magnesium flux of 30 standard cubic centimeter per minute would significantly reduce the grain size to as low as ∼ 550 nm (±1 nm), yielding a root mean square roughness of 6.00 nm. X-ray rocking curve analysis observed that a moderate biscyclopentadienyl magnesium flow rate of 30 standard cubic centimeter per minute leads to narrowing in full width at half maximum, indicating an enhanced crystallinity with a reduction of the basal stacking fault density of 8.18 × 104 cm−1 with the use of 30 standard cubic centimeter per minute of biscyclopentadienyl magnesium. Moreover, the mobilities and carrier concentrations were improved to as high as 1.8 cm2.V − 1.s − 1 and 5.5 × 1017 cm−3 with a moderate biscyclopentadienyl magnesium flow rate of 30 standard cubic centimeter per minute. The analysis suggests that with the optimum biscyclopentadienyl magnesium flow rate (30 standard cubic centimeter per minute), preferential sites for magnesium incorporation can be enhanced.

Novel zinc alumina bismuth borate glass system was fabricated according to the empirical formula x(ZnO)–5(Al2O3)–30(BiO3)–65-x(B2O3) with x = 0, 5, 10, 15, 20, 25 and 30 mol% using conventional glass melt-quenching technique. The structural, elastic and shielding properties of the ZnO–Al2O3–BiO3–B2O3 glasses were examined by X-ray diffraction (XRD), density, molar volume, ultrasonic velocities, and EPICS2017 simulation. The glass structure's amorphous phase was confirmed by XRD measurement. From the density measurement, the addition of ZnO will increase the density from 4.275 to 5.018 g/cm3 and the molar volume decreased from 44.479 to 38.595 cm3/mol. In addition, the OPD is decreased from 67.45 to 62.19 mol/cm3. The elastic properties approximated from measured shear (VS) and longitudinal (VL) ultrasonic velocities indicated that the decrease of B2O3 in glass network cause the rigidity of glasses increased from 2300 to 2621 m/s and 4082–4540 m/s when the ZnO content increased. Meanwhile, the longitudinal (L), shear (G), bulk (K) and Young's (E) modulus increased from 71.23 to 103.43 GPa, 22.61–34.47 GPa, 41.08–57.47 GPa and 57.29 and 86.18 GPa. Besides, Poisson's ratio decreased from 0.267 to 0.250 and micro hardness increased from 3.51 to 5.75 GPa. The EPICS2017 simulation program is used to determine the radiation shielding of the glasses. The results show a very interesting results where the replacement of B2O3 by ZnO causes an improvement of the attenuation competence for the glasses.

The ores of Big Karatau are a valuable, currently unused source of rare and rare earth elements (REEs). To develop an integrated technology for processing black shale ore, it was studied using chemical, X-ray phase, infrared, mineralogical, X-ray spectral, and electron microscopic analyses. Rare and particularly REEs in the ore are found in various minerals in the form of inclusions in the siliceouscarbonaceous matrix. This explains the failures of the previously proposed processing methods, which either resulted in the incomplete extraction of the valuable components or were not profitable. For more complete extraction, novel ore processing approaches are required. A method for the early development of the original black shale ore using sintering with (NH4)2SO4 in the presence of concentrated H2SO4, followed by leaching of the cake with a diluted H2SO4 solution, is proposed. The optimal conditions for each stage are determined. The kinetic dependencies of the extraction of rare and REEs from sulfated cake under the most suitable conditions yielded maximum extractions of 98% for U, 92% for V, 89% for Mo, and 78% for the REEs. The rate constant and effective activation energy of V leaching, as the most representative of the rare and rare earth metals, were calculated. The process was limited by diffusion. After the leaching of the valuable components, the cake may be used in froth flotation enrichment to recover the carbonaceous material, and then it may be used as part of the charge to obtain ferrosilicon. The solution obtained from the leaching of the initial cake may be used to recover U, Mo, V, and the REEs using sorption.

Neodymium oxide doped tellurite-based glass has been widely documented for potential uses in optoelectronics, but graphene oxide (GO)-coated tellurite-based glass has rarely been reported. In this work, we compare two sets of glass series which were GO-coated and uncoated tellurite-based glass series denoted as ZBTNd-GO and ZBTNd, respectively. The two sets of glasses were fabricated via melt-quenched process. A set of glass was coated with GO using low-cost spray coating method. The structural and morphological properties of the glass samples were investigated to confirm the type of structure in glass and formation of graphene oxide on glass surface. The X-ray diffraction (XRD) pattern confirmed the amorphous structural arrangement in both sets of glass series. The morphological study proved the existence of GO layers on top of the ZBTNd-GO surface. The optical bandgap energy of ZBTNd-GO glass was found in the range of 3.253 eV–3.381 eV which was higher than ZBTNd glass. Meanwhile, the refractive index of ZBTNd-GO glass varies from 2.301 to 2.332 which was higher than ZBTNd glass due to the presence of functionalized oxygenated groups in GO structure. The oxide ion polarizability of ZBTNd-GO glass was found decreased due to the shift of optical band gap when coated with GO. This work offers a new form of glass that could be used as a new strategy to upgrade the current photonic materials.

Judd–Ofelt (J–O) theory was used to analyze the optical properties of erbium (Er3+) ions doped zinc-sodium-tellurite glass system incorporated with titania (TiO2) nanoparticles (TNPs) for the realization of up-converted solid state lasers. Such glass systems were synthesized using melt quenching method to determine the influence of varying TNPs contents on the absorption and emission properties. J-O intensity parameters (Ω2, Ω4, Ω6), spectroscopic quality factor (χ = Ω4/Ω6), radiative transition probabilities, branching ratio, and radiative lifetime of various transitions involved in the Er3+ ions were calculated from the measured optical spectra. XRD pattern verified the amorphous nature of the prepared glass samples. TEM images manifested the growth of TNPs inside the glass matrix having mean size between 15 and 25 nm. UV–Vis–NIR spectra exhibited ten absorption bands centred at 407, 444, 452, 489, 522, 552, 653, 800, 976 and 1532 nm. Two surface plasmon resonance (SPR) bands of TNPs were evidenced at 552 nm and 580 nm. Luminescence spectra revealed three prominent peaks centred at 525, 545 and 660 nm, where the glass sample containing 0.2 mol% of TNPs displayed optimum intensity enhancement by a factor of 30.00, 28.57 and 19.60, respectively. This enhancement is primarily attributed to the TNPs surface plasmon enabled colossal localized electric field in the proximity of Er3+ ions and subsequent energy transfer to the Er3+ ions. Values of Ω2, Ω4, Ω6 and χ were ranged between (2.14−3.72)×10−20, (1.27−2.77)×10−20, (1.42−2.22)×10−20 cm2 and (0.58–1.94), respectively. Occurrence of higher values of Ω2 and Ω6 indicated the existence of lower symmetry and stronger covalency around the Er3+ ions. Furthermore, the decrease of χ values with increasing TNPs up to 0.2 mol% approved intensified lasing transition. Achieved higher values of Ω4 and Ω6 demonstrated that the present glass composition is a prospective lasing media.

The aim of this work is to determine the effect of Nd3+ ion concentration on the elastic properties of zinc-tellurite glass for the development of waveguide lasers. A series of Neodymium doped zinc-tellurite (NZT) glass system of composition [(TeO2) 0.70 (ZnO) 0.30] (1-x) Nd2O3 (x), x =0, 0.01, 0.02, 0.03, 0.04 and 0.05, were synthesized by using conventional melt-quenching method. XRD analysis confirmed the amorphous nature of the glass; the FTIR confirmed the presence of TeO3 and TeO4 in the glass network. The density of the glass system increases with increase in neodymium concentration. The longitudinal ultrasonic velocity decreases from 3737.01 to 3045.23 ± 10 ms−1, and the shear velocity decreases from 1959.31 to 1887.81 ± 10 ms−1. The experimental results have shown that the elastic properties depend on the composition of the glass systems and the effect of neodymium (Nd2O3) within the glass network.

A glass series of erbium doped zinc borotellurite glass system was prepared by using the melt-quenching method. The absorption spectra revealed several bands at visible range which correspond to the following transitions (from the ground state); 4G11/2 + 2H9/2 + 4F5/2 + 4F7/2 + 2H11/2 + 4S3/2 + 4F9/2 + 4I9/2 + 4I11/2. From the Judd–Ofelt analysis, it is found that the trend of Ω2 values is a non-linear variation along with erbium concentrations. Meanwhile, the value of Ω6 decreases as the erbium concentration increases. The photoluminescence analysis shows green emission which are attributed to the 4S3/2 level to the ground state at 4I15/2. Meanwhile, the upconversion analysis revealed several emission bands at 376 nm, 424 nm, 470 nm and 558 nm which correspond to 4G11/2 → 4I15/2, 4F3/2 → 4I15/2, 4F7/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions respectively. The non-linear refractive index spectra show self-defocusing behavior and negative nonlinear refraction (ƞ2

Zinc borotellurite glasses doped with lanthanum oxide were successfully prepared through melt-quenching technique. The amorphous nature of the glass system was validated by the presence of a broad hump in the XRD result. The refractive index of the prepared glass samples was calculated by using the equation proposed by Dimitrov and Sakka. The theoretical value of molar refraction, electronic polarizability, oxide ion polarizability and metallization criterion were calculated by using Lorentz-Lorenz equation. Meanwhile, expression proposed by Duffy and Ingram for the theoretical value of optical basicity of multi-component glasses were applied to obtain energy band gap based optical basicity and refractive index based optical basicity. The optical basicity of prepared glasses decreased with the increasing concentration of lanthanum oxide. Metallization criterion on the basis of refractive index showed an increasing trend while energy band gap based metallization criterion showed a decreasing trend. The small metallization criterion values of the glass samples represent that the width of the conduction band becomes larger which increase the tendency for metallization of the glasses. The results obtained indicates that the fabricated glasses have high potential to be applied on optical limiting devices in photonic field. Keywords: Borotellurite glasses, Refractive index, Electronic polarizability, Oxide ion polarizability, Optical basicity, Metallization criterion

Comparative analysis on optical properties between two glass series (a—ordinary glass, b—glass with nanoparticles) have been estimated. The two glass series (a—ordinary glass, b—glass with nanoparticles) with compositions {[(TeO2)0.70 (B2O3)0.30]0.70 (ZnO)0.30}1−y (Er2O3/Er2O3 nanoparticles)y; y = 0.005, 0.01, 0.02, 0.03, 0.04, 0.05 mol% were successfully prepared by using melt-quenching method. The TEM, EDX and XRD have been used to confirm the existence of nanoparticles and all elements in the glass system. The density of b—glass with nanoparticles are found greater than a—ordinary glass. The optical properties of the glass series were characterized by using Ellipsometer and UV–Vis spectrophotometer. There is a linear increasing trend in refractive index of the glass series along with concentration of erbium and erbium nanoparticles oxide. The refractive index of b—glass with nanoparticles is greater than a—ordinary glass. Moreover, the absorption peaks of a—ordinary glass are more intense than b—glass with nanoparticles. The glass with nanoparticles will offer a potential materials for nanophotonic devices.

The glass series of samarium nanoparticles (NPs) doped zinc borotellurite glasses were successfully fabricated by using conventional melt-quenching technique. The structural properties of the prepared glasses were investigated by X-ray diffraction (XRD) analysis and FTIR analysis. It was confirmed that the prepared glasses are amorphous in nature. The bonding parameters of the glasses were analyzed by using FTIR analysis and were found the formation of non-bridging oxygen. The density of these glasses were measured and found to be increased with increasing samarium NPs content. The optical absorption spectra of these glasses were revealed that the fundamental absorption edge shifts to higher wavelengths as the content of Sm2O3 (NPs) increases. The optical energy band gap are found to be decreased linearly with an increasing samarium NPs concentration which is due to the formation of non-bridging oxygen in the glass system.KeywordsBorotellurite glass; optical band gap, Samarium nanoparticles.

Neodymium doped zinc borotellurite glass system were fabricated by using conventional melt-quenching method. The structural properties of the glass system were characterized by using X-ray Diffraction (XRD) method and Fourier Transform analysis (FTIR). The amorphous nature of the glass system was confirmed by using x-ray diffraction method. The transmission band of TeO3 structural units which indicate the existence of non-bridging oxygen was shown by FTIR analysis. The optical properties of the glass system were determined by using UV-Vis spectrophotometer. Several bands were shown in the absorption spectra which indicate the characteristic of neodymium ions. The obtained values of indirect optical band gap, Eopt lies in the range of 3.151 eV and 3.184 eV.

Efficient, inexpensive and eye−safe new host glass as up−conversion (UC) emission solid−state laser media became demanding. Nanoparticles (NPs) of various noble metals have been inserted into the phosphate−based amorphous host matrix to enhance the rare-earth ions (REIs) stimulated emission cross−section. Furthermore, only a few reports exist on the combined influences of neodymium ions (Nd3+) and pure silver (Ag) NPs on the structural and optical response of magnesium zinc sulfophosphate (MZSP) glasses. In this view, a series of MZSP glasses were doped by Nd3+ ions and pure Ag NPs (at different concentrations) to improve their structural and optical properties. Such melt−quench synthesized glasses were characterized at room temperature using diverse analytical measurement tools. The XRD pattern of as−quenched samples approved their amorphous nature. The FTIR and Raman spectra of glasses revealed the presence of characteristic bonding vibrations of different functional groups. The TEM images showed the existence of spherical Ag NPs (mean size of 8.34 nm) in the host glass matrix. The surface plasmon resonance (SPR) band of Ag NPs was detected around 451 nm. The UV–Vis–NIR absorption and PL emission spectra of glasses were utilized to evaluate the Judd−Ofelt (JO) intensity parameters ( Ω 2 , Ω 4 and Ω 6 ) and radiative properties. The observed fluctuation in the Ω 2 values with the increase in Ag NPs contents was attributed to the dynamic change of ligands symmetry around Nd3+ inside the glass network. Variations in the Ω 4 and Ω 6 values with the increase in Ag NPs contents indicated a considerable reduction in the glass rigidity. The PL spectra of glasses exhibited a prominent band around 576–584 nm corresponding to the 2G7/2 +4G5/2 → 4I9/2 transition in Nd3+. Glass prepared with 0.5 mol% of Ag NPs disclosed the highest PL enhancement (≈19 times) and largest emission cross−section (≈4.35 × 10−24 cm2) which was ascribed to the synergism between Ag NPs SPR mediated strong local field effect (LFE) and the subsequent energy transfer to Nd3+ appeared in the proximity of NPs. It was concluded that the proposed glass composition can lead to the development of UC solid−state laser compared to many other reported glass system.

In this work, we synthesize graphene oxide (GO)-coated tellurite glass for the improved optical performance of fiber optics. A series of tellurite glass system with composition of {[(TeO2)0.7 (B2O3)0.3]0.7 (ZnO) 0.3}1-y (Er2O3) y where y (mol%) = 0.005, 0.01, 0.02, 0.03, 0.04and 0.05 mol% was successfully fabricated and coated with GO by using melt-quenching and spray coating methods. The structural properties were characterized by using XRD analysis and FESEM. The XRD patterns indicated that the tellurite glass were amorphous. The FTIR transmissions images revealed the surface morphology of GO on the glass surface. The optical band gap energy was found enhanced from 3.392 to 3.495 eV. The refractive index was found improved from 2.275 to 2.299 with the existence of GO. Hence, these results were useful for the application of fiber optics.

A series of neodymium NPs doped tellurite glass with composition of (TeO2)0.7(B2O3)0.3]0.7 (ZnO)0.3}1- x (Nd2O3 NPs) x (x = 0.005, 0.01, 0.02, 0.03, 0.04 and 0.05 mol%) was fabricated via melt-quenching method. Density and molar volume were measured and analyzed for the glass series. The optical properties of neodymium NPs doped tellurite glass were measured by UV–Vis spectrometer, photoluminescence and Z-scan technique. The optical band gap energy of the glass network was in the range of 3.178–3.209 eV. The upconversion emission of the laser glass excited at 800 nm was found in the ultraviolet region. Electronic polarizability, oxide ion polarizability, optical basicity and metallization criterion were calculated. Moreover, linear absorption coefficient, α, nonlinear refractive index ƞ (cm2/W), nonlinear absorption, β (x 10−3) and third order susceptibilities, χ (x 10−6) were measured. The optical efficiency of neodymium NPs doped tellurite glass exhibited excellent properties for its application in laser glass.

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.

Successful extraction of high purity SiO2 (about 99%) from rice husk (waste) was achieved in this work using the cold acid leaching method. Glass series [(TeO2)0.7 (B2O3)0.3]1-x (SiO2)x were fabricated using the rice husk silicate (RHS) by melt-quenching method. The samples were subjected to X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) characterization to study the structural nature of the glass system. Density and ultrasonic velocities were measured to obtain the elastic constants for the various silicate proportions in the glass using ultrasonic data obtained from non-destructive ultrasonic probing technique. The elastic moduli calculated from the obtained data were found to have increased with the addition of more RHS in the glass. Other parameters studied include the microhardness (H), Poisson's ratio (σ), softening temperature (ϴD) and fractal bond connectivity (d) and the fluctuation free volume (fugacity, fg). A very unusual occurrence was observed as microhardness value decreases in the glass system as more RHS (SiO2) is introduced. The quality of the glass in terms of elastic behavior improved with addition of RHS in the borotellurite glass network.

The glass series with composition of {[(TeO 2 ) 0.70 (B 2 O 3 ) 0.30 ] 0.7 (ZnO) 0.3 } 1-y (Nd 2 O 3 ) y where, y = 0.005, 0.01, 0.02, 0.03, 0.04 and 0.05; was fabricated via melt-quenched technique. The third-order optical nonlinearity was observed by using Z-scan technique. Polarizability and third-order nonlinearity of borotellurite glass doped with neodymium (Nd 3+ ) will be reported. This work presents the effect of neodymium ions on the linear and nonlinear optical performance of borotellurite glass for potential photonics applications. The structure and optical performance of the resulting transparent neodymium doped borotellurite glass are characterized. The reduction of optical band gap energy, E g is observed which shows the alteration of tellurite structure by the Nd 3+ . The values of electronic polarizability are enhanced with an increase of Nd 3+ ions. The enhancement of electronic polarizability provides an excellent medium for nonlinear optical applications. The optical basicity of the investigated materials shows non-linear trend along with Nd 3+ ions concentration. The Z-scan data for third-order optical nonlinearities suggest that the glass materials are excellent to be used as a medium in nonlinear optical fiber. Therefore, the investigated glass materials may provide a good material for photonic applications.