Özet:
This thesis comprehensively investigates the structural, thermal, mechanical, optical, elastic, and radiation shielding properties of boro-tellurite-based glasses doped with varying concentrations of hafnium oxide (HfO₂), targeting advanced applications in medical and nuclear radiation protection. The glass system, composed of TeO₂–B₂O₃–WO₃–HfO₂, was synthesized using the conventional meltquenching technique with HfO₂ content ranging from 0 to 10 mol%.
X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analyses confirmed the amorphous structure and the stability of the glass network. Raman spectroscopy further revealed a shift in the characteristic TeO₂ vibrational bands from 561 cm⁻¹ to 547 cm⁻¹, signifying structural reorganization through the formation of Hf–O bonds. The incorporation of HfO₂ induced a more compact structure, as evidenced by a reduction in molar volume from 33.20 cm³/mol to 31.85 cm³/mol and an increase in glass density from 4.48 g/cm³ to 4.83 g/cm³.Thermal properties were significantly improved with increasing HfO₂ concentration. The glass transition temperature (Tg) increased from 402 °C (T1) to 419 °C (T6), while the softening temperature rose from 773 K to 952 K. The Debye temperature also increased from 284 K to 314 K, indicating enhanced thermal stability. Mechanical performance was similarly enhanced, with microhardness rising from 3.74 GPa to 3.98 GPa and fracture toughness increasing from 0.26 MPa·m¹ᐟ², reflecting the strengthening of the glass matrix.Optical studies revealed a decline in the optical band gap from 2.99 eV to 1.95 eV with increasing HfO₂ content, indicating increased electronic polarizability and potential for optoelectronic use.
Radiation shielding characteristics demonstrated a remarkable improvement due to HfO₂ doping. Gamma-ray shielding efficiency increased with HfO₂ content, particularly at lower photon energies. At 80.99 keV, the mass attenuation coefficient (MAC) increased from 2.746 cm²/g (T1) to 3.246 cm²/g (T6), while the mean free path (MFP) at 0.356 MeV decreased from 1.6299 cm to 1.4510 cm, enhancing photon attenuation capability. Additionally, neutron shielding was significantly improved;the fast neutron removal cross-section (ƩR) reached its maximum in the T4 sample, resulting in a 30.68% increase in neutron dose absorption compared to the undoped glass.
In conclusion, the integration of HfO₂ into the TeO₂–B₂O₃–WO₃ glass matrix not only enhances structural compactness, thermal and mechanical resilience, and optical properties, but also markedly strengthens gamma and neutron radiation shielding efficiency. These results highlight the potential of HfO₂-doped boro-tellurite glasses as promising multifunctional materials for use in harsh environments requiring robust thermal, mechanical, and radiation resistance particularly in nuclear technology, radiation shielding systems, and biomedical applications.
