Effect of heat treatment on physical properties of rare earth doped glasses
Naglaa fathy Osman Mansour;
Abstract
The transparent glasses of composition 40P2O5-20ZnO-(40-x)Na2O-xLi2O (where 0 ≤ x ≤ 25 Li2O mol. %) and the glass samples doped with Nd3+ were prepared using the conventional melt quenching technique. The physical, optical, and electrical properties of the prepared glass samples were characterized by x-ray diffraction (XRD), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), and UV-VIS optical absorption.
The amorphous nature of the prepared glass samples is confirmed by (XRD). The differential thermal analysis (DTA) studies showed that the glass transition temperature (Tg) decreased as the content of Li2O increased till 25 mol. % Li2O and it was found that the glass samples with 15 mol. % Li2O has the highest thermal stability. For Nd2O3 doped glasses, (Tg) increased with Nd2O3 content. The density and oxygen packing density measurements are found to be increase while the molar volume decreases with increasing of Li2O content which indicates that the structure is more compact. The FTIR studies revealed that these glasses consist of Q3, Q2, Q1 and Q0 structural units.
Absorbance of investigated glasses was measured and used to estimate their optical absorption coefficient and optical energy gap. The optical studies revealed that the indirect optical band gap (Eg) decreases from 3.33 to 2.64 eV and Urbach energy increases from 0.46 to 2.4eV with increasing of Li2O content from zero to 25 mol. % Li2O. The effect of annealing on the absorption coefficient spectra of the samples in the UV-VIS range were studied and It is found that the optical band gap (Eg) decreases from 3.217 to 2.66 eV before annealing and decreases from 2.72 to 2.33 eV after annealing with increasing Nd2O3 content.
The dc, ac electrical conductivity (σdc and σac) and dielectric constants (ε' and ε'') of all the samples have been investigated. It is found that the dc conductivity increases with the concentration of Li2O mol. % and the temperature dependence of the dc conductivity at low temperature (303 – 383 K) and at high temperature (403 – 473 K) obey the Arrhenius law. The activation energies ΔEdc1 (at high temperatures) and ΔEdc2 (at low temperatures) were determined. With increasing Nd2O3 content σdc increase while the values of the activation energies ΔE1 and ΔE2 decrease. dc conductivity (σdc) and activation energies (ΔE1, ΔE2) found to be affected by annealing. The values of σdc can be obtained also from the impedance study at different temperatures and different concentrations using Cole-Cole plot.
The amorphous nature of the prepared glass samples is confirmed by (XRD). The differential thermal analysis (DTA) studies showed that the glass transition temperature (Tg) decreased as the content of Li2O increased till 25 mol. % Li2O and it was found that the glass samples with 15 mol. % Li2O has the highest thermal stability. For Nd2O3 doped glasses, (Tg) increased with Nd2O3 content. The density and oxygen packing density measurements are found to be increase while the molar volume decreases with increasing of Li2O content which indicates that the structure is more compact. The FTIR studies revealed that these glasses consist of Q3, Q2, Q1 and Q0 structural units.
Absorbance of investigated glasses was measured and used to estimate their optical absorption coefficient and optical energy gap. The optical studies revealed that the indirect optical band gap (Eg) decreases from 3.33 to 2.64 eV and Urbach energy increases from 0.46 to 2.4eV with increasing of Li2O content from zero to 25 mol. % Li2O. The effect of annealing on the absorption coefficient spectra of the samples in the UV-VIS range were studied and It is found that the optical band gap (Eg) decreases from 3.217 to 2.66 eV before annealing and decreases from 2.72 to 2.33 eV after annealing with increasing Nd2O3 content.
The dc, ac electrical conductivity (σdc and σac) and dielectric constants (ε' and ε'') of all the samples have been investigated. It is found that the dc conductivity increases with the concentration of Li2O mol. % and the temperature dependence of the dc conductivity at low temperature (303 – 383 K) and at high temperature (403 – 473 K) obey the Arrhenius law. The activation energies ΔEdc1 (at high temperatures) and ΔEdc2 (at low temperatures) were determined. With increasing Nd2O3 content σdc increase while the values of the activation energies ΔE1 and ΔE2 decrease. dc conductivity (σdc) and activation energies (ΔE1, ΔE2) found to be affected by annealing. The values of σdc can be obtained also from the impedance study at different temperatures and different concentrations using Cole-Cole plot.
Other data
| Title | Effect of heat treatment on physical properties of rare earth doped glasses | Other Titles | تأثير المعالجة الحرارية على الخواص الفيزيائية للزجاجيات المطعمة بالعناصر النادرة | Authors | Naglaa fathy Osman Mansour | Issue Date | 2020 |
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