تحت اشراف قسم الفيزياء و بالتعاون مع مركز البحوث اقيم يوم الاثنين الموافق 18- 11- 2019 سيمنار بعنوان:

Synthesis and characterization of Mn+2-doped zinc silicate as potential

green nanophosphor materials

قدمته الدكتورة/ نجلاء عبد العال و ذلك في تمام الساعة 11 في قاعة الاجتماعات بقسم الفيزياء.

Abstract:

 Pure and Mn?2-doped Zn2SiO4 nanocomposite materials were synthesized using a sol–gel method. The structural, optical, dielectric and magnetic properties of prepared samples were studied using different techniques. X-ray diffraction results show that the dominant phase is willemite (a-Zn2SiO4) with rhombohedral structure and average crystallite size varied from 70 to 90 nm. Photoluminescence spectra, PL of Zn2SiO4, have two broadband emissions centered at 375 nm and 760 nm. PL spectra of Zn2SiO4/Mn is characterized by one dominant peak at 525 and attributed to 4T1–6A1 transitions of Mn2? ions. Photoluminescence excitation, PLE of Zn2SiO4/Mn at 78 K, has strong excitation band from 240 to 300 nm with maximum at about 255 nm (4.9 eV) compared to the bands in UV–Vis range. Dielectric constant, dielectric loss tangent and electrical conductivity of prepared samples are studied as a function of electric field frequency and indicated a strong dependent on Mn?2 ions. Zn2SiO4 and Zn2SiO4/Mn?2 have diamagnetic properties at room temperature at 300 K, while Zn2SiO4/Mn?2 has a ferromagnetic behavior at 5 K.