1. Department of Materials Engineering, University of Concepción, Concepción, Chile%SR92-01.68
2. Materials and Minerals Division, National Institute for Interdisciplinary Science and Technology (NIIST),CSIR, Trivandrum, India%SR92-01.57
3. Department of Physics, University of Concepción, Chile%SR92-01.68
4. Department of Environmental Technology and Urban Planning, Nagoya Institute of Technology, Nagoya, Japan%SR92-01.51
5. Department of Nuclear Materials, Chilean Commission of Nuclear Energy, Santiago, Chile%SR92-01.68