Caracterización estructural y espectroscópica de fibras cristalinas de Ce_0.4Zr_0.6O₂ crecidas mediante el método de fusión zonal asistida por láser

Abstract

A structural and spectroscopic characterization of crystalline rods of Ce 0.4 Zr 0.6 O 2 grown by the laser floating zone (LFZ) method is presented. A precursor rod of Ce 0.4 Zr 0.6 O 2 composition was sintered at 1500 ºC in air atmosphere and then processed by the LFZ technique with a CO 2 laser. The processed material was characterized by XRD, SEM and Raman spectroscopy. In the as-grown, dark-color processed rod, the Raman spectrum evolves radially from a t'-like one, corresponding to Ce 0.37 Zr 0.63 O 2 composition, at the edge of the rod, to a very broad and weak, cubic-like one, at the center. The degree of cerium reduction and oxygen non-stoichiometry were determined through measurements of the electronic Raman spectrum of Ce 3+. A strong Ce 3+ signal was found at the core of the rod, indicating strong reduction, whereas no Ce 3+ signal was detected at the edge. To restore oxygen and Ce 4+ content a section of the fiber was reoxidized at 620 ºC for 24 h. A very homogeneous spectrum was found in the reoxidized sample, that was assigned to a t'-phase of composition Ce 0.42 Zr 0.58 O 2 .