Indra Gunawan
Center for Technology of Nuclear Industry Materials-National Nuclear Energy Agency Kawasan Puspiptek Serpong 15314, Tangerang, Indonesia
Indonesia

Hildayati Hildayati
Dept. of Physics, Fac. of Math. and Natural Sciences-Sepuluh November Institute of Tech. Surabaya Kampus ITS Sukolilo, Surabaya 60111, Indonesia

Sudirman Sudirman
Center for Technology of Nuclear Industry Materials-National Nuclear Energy Agency Kawasan Puspiptek Serpong 15314, Tangerang, Indonesia

Emil Budianto
Dept. of Chemistry, Fac. of Math. and Natural Sciences-University of Indonesia Kampus Baru UI, Depok 16424, Indonesia
Indonesia