Influence of solvents and irradiation time on structural and optical properties of cubic PbS nanoparticles

In the present paper, different particle sizes of lead sulfide (PbS) nanoparticles with a cubic structure were successfully prepared using a microwave irradiation method from lead acetate [(CH₃COO)₂Pb.3H₂O] and thioacetamide (CH₃CSNH₂) as the starting materials. Ethylene glycol (C₂H₆O₂), distilled water (H₂O), ethylene alcohol (C₂H₅OH) and isopropanol (C₃H₈O) were used as solvents and a 650W oven operating at 20% of the nominal power in the period of 10 min was employed. The effect of the microwave irradiation time was investigated by varying the irradiation time from 10 to 50 minutes respectively. The resulting nanoparticles in different sizes were characterized using X–ray diffraction, Transmission electron microscopy (TEM) and UV–Vis absorption spectroscopy. The crystallite sizes were calculated from the broadening of the XRD peak using Scherrer’s equation. The results showed that the increased intensity of the XRD peak and the dipole moment of the solvents being decreased corresponded with the reduction in particle sizes. The TEM results indicated that the samples consisted of separated, well–defined spherical particles and showed a small distribution size. As can be seen from the UV–vis spectrum, the band gap energy of each sample had increased and showed a characteristic blue shift due to the quantum confinement in their optical absorption. The mechanism that influenced the solvents and irradiation time for the formation of the PbS nanoparticles were discussed

Preparation and Elastic Moduli of Germanate Glass Containing Lead and Bismuth

This paper reports the rapid melt quenching technique preparation for the new family of bismuth-lead germanate glass (BPG) systems in the form of (GeO2)60–(PbO)40−x–(½Bi2O3)x where x = 0 to 40 mol%. Their densities with respect of Bi2O3 concentration were determined using Archimedes’ method with acetone as a floatation medium. The current experimental data are compared with those of bismuth lead borate (B2O3)20–(PbO)80−x–(Bi2O3)x. The elastic properties of BPG were studied using the ultrasonic pulse-echo technique where both longitudinal and transverse sound wave velocities have been measured in each glass samples at a frequency of 15 MHz and at room temperature. Experimental data shows that all the physical parameters of BPG including density and molar volume, both longitudinal and transverse velocities increase linearly with increasing of Bi2O3 content in the germanate glass network. Their elastic moduli such as longitudinal, shear and Young’s also increase linearly with addition of Bi2O3 but the bulk modulus did not. The Poisson’s ratio and fractal dimensionality are also found to vary linearly with the Bi2O3 concentration

Perbedaan Tingkat Depresi Antara Guru Yang Mengajar Di Slb Negeri Surakarta Dengan Guru Yang Mengajar Di SMP Negeri 1 Surakarta

Background: Demands work experience on the Extraordinary School’s teachers, of course different with the problem on the Junior High School’s teachers. Teacher is one profession jobs have a level of depression most of all in the aspects of physical, psychology and job satisfaction. Depression is a disturbance in the mood of the most common happen characterized by a state of stress, loss of pleasure or interest, there's feeling of guilty or self-esteem is low, less until loss of appetite, having sleep disorder, lack of energy, and difficulty concentrating. Objective: this study aims to analyze the existence of difference levels of depression among teachers who teach at SLB Negeri Surakarta with teachers who teach in SMP Negeri 1 Surakarta and frequency distribution of difference levels of depression among teachers who teach at SLB Negeri Surakarta with teachers who teach in SMP Negeri 1 Surakarta. Methods: this research is a study of analytical observational, with the use of cross sectional. Results: based on data of questionnaire BDI on teachers who teach at SLB Negeri Surakarta and teachers who teach in SMP Negeri 1 Surakarta tested using Mann-Whithney, no different at trial was obtained by teachers who teach at SLB Negeri Surakarta with teachers who teach in SMP Negeri 1 Surakarta has the value p = 0,040 (p < 0,05) which means that is a meaningful statistic. Conclusion: there is a difference in the level of depression among teachers that taught at the SLB Negeri of Surakarta with teachers who teach in SMP Negeri 1 Surakarta. The level of depression, owned a teacher who teaches at SLB Negeri Surakarta is higher compared with teachers who teach in SMP Negeri 1 Surakarta. Keywords: Extraordinary School’s Teacher, Junior High School’s Teacher, Depressio

THE ROLE OF Er2O3 IN THE TeO2-ZnO GLASS SYSTEM: MECHANICAL AND GAMMA-RAY SHIELDING CHARACTERISTICS

Mechanical and shielding properties are affected by the addition erbium oxide in the Zinc-tellurite glasses

Anomalous elastic and optical behaviours of mixed electronic-ionic of xAg2O-(35-x)[0.5MoO3-0.5V2O5]-65TeO2 conductor glasses

Ag2O addition to quaternary xAg2O-(35-x)[0.5MoO3-0.5V2O5]-65TeO2 (x = 0-25 mol%) glasses resulted in nonlinear behaviours with maxima at x = 10 mol% for ultrasonic velocities, independent elastic moduli and transition glass temperature (Tg). These results coincided with the electronic-to-ionic transition region as previously reported. A large decrease in elastic moduli beyond x ≤ 10 mol% indicated a decrease in stiffness, thereby enabling ionic conductivity. Although Ag2O addition weakened the glass network, the presence of MoO3 played an important role as an additional glass former at x = 10 mol% apart from V2O5. Analysis of bulk compression and ring deformation models showed a large decrease in the ratio of theoretical to experimental bulk moduli (Kbc/Ke) at x ≤ 10 mol% followed by near constancy with increased Ag2O content. These results showed that ring deformation was reduced in the electronic region, but limited ring deformation took place in the ionic region, and that the main compression mechanism was mainly isotropic ring compression. Meanwhile, the optical energy gap (Eopt) and refractive index (n) showed a slope change at x = 10 mol% which confirmed the effect of mixed electronicionic conductivity on optical properties. © 2016, National Institute R and D of Materials Physics

Optical properties of zinc borotellurite glass doped with trivalent dysprosium ion

The zinc borotellurite doped with dysprosium oxide glass samples with chemical formula {[(TeO ) (B O ) ] (ZnO) } (Dy O ) 2 0.7 2 3 0.3 0.7 0.3 1−x 2 3 x (where x=0.01, 0.02, 0.03, 0.04 and 0.05 M fraction) were prepared by using conventional melt quenching technique. The structural and optical properties of the proposed glass systems were characterized by using X-ray diffraction (XRD) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and UV–VIS spectroscopy. The amorphous nature of the glass systems is confirmed by using XRD technique. The infrared spectra of the glass systems indicate three obvious absorption bands which are assigned to BO3 and TeO4 vibrational groups. Based on the absorption spectra obtained, the direct and indirect optical band gaps, as well as the Urbach energy were calculated. It is observed that both the direct and indirect optical band gaps increase with the concentration of Dy3+ ions. On the other hand, the Urbach energy is observed to decrease as the concentration of Dy3+ ions increases

Determinants of UK students' financial anxiety amidst COVID‐19: Financial literacy and attitudes towards debt

Due to the increased financial pressure—exacerbated by the COVID-19 pandemic—that students in higher education need to endure, considerable attention is being drawn towards the determinants of student financial anxiety. A conflicting picture has been captured about financial literacy, which has been shown to either be associated with better financial well-being or to be unrelated to financial stress. While discerning between financial knowledge (‘objective’ financial literacy) and perceived ability to manage personal finances (‘subjective’ financial literacy), this study also explores the impact that students' attitudes towards debt may exert on their financial anxiety. In a sample of 174 university students from the UK, we measured students' financial anxiety, objective and subjective financial literacy, attitudes towards debt and perceived impact of COVID-19 on financial behaviour. Bayesian analyses revealed that only attitudes towards debt and perception of the impact of the pandemic predicted students' financial anxiety. While the evidence in regard to financial literacy was inconclusive, mediation analyses showed that objective financial literacy indirectly impacted financial anxiety by increasing fear of debt. The findings suggest that students' financial anxiety may be reduced by adopting strategies that focus on the subjective perception of debt and of economic circumstances

Structural and optical properties of Tm2O3-doped zinc borotellurite glass system

Thulium doped zinc borotellurite glasses with composition {[(TeO2)0.7(B2O3)0.3]0.7[ZnO]0.3}1-x{Tm2O3}x were synthesized using melt-quenching technique. The values of x varied from 0.01 to 0.05 mol. The density and molar volume of the glass samples were found to increase with increased concentration of thulium oxide. FTIR analysis showed the existence of TeO4, BO3 and BO4 structural units in the glass network as well as the formation of bridging oxygens. XRD patterns confirmed the amorphous nature of the glass and were supported by the absence of sharp edges in the absorption spectra. All the optical data was found to vary with the concentration of Tm2O3. The direct and indirect optical band gap was in the range of 4.19 to 4.38 eV and 3.62 to 3.79 eV respectively. The trend for refractive index, molar refraction and molar polarizability was in opposite trend to the optical band gap and Urbach energy due to the variation of non-bridging oxygens (NBOs), increment of cross-link density, and also the existence of free electrons in the glass system