of;
Physics;
Hanoi;
Pedagogical;
University;
No.2;
Xuan;
Hoa;
Phuc;
Yen;
Vinh;
Phue;
Vietnam;
Engineering;
&;
Nanotechnology;
and;
Technology;
National;
144;
Thuy;
str.;
Cau;
-Giay;
Dist.;
1000;
Materials;
Science;
Academy;
18;
Hoang-Quoc-Viet;