FERNÁNDEZ CARRIÓN , Alberto José

La familia de los disilicatos de tierras raras (de fórmula general RE2Si2O7) exhibe, a presión atmosférica, un elevado polimorfismo con la temperatura (hasta 7 formas diferentes), cuyas estructuras y campos de estabilidad fueron bien definidos por Felsche.[1] Es bien sabido que esta familia de compuestos pueden formar soluciones sólidas entre...

Phase transitions in LaYSi 2O 7 have been investigated as a function of temperature using XRD, NMR and TEM. Previously described empirical crystal structure guidelines based on average cation radius in rare-earth RE 2Si 2O 7-type disilicates predict a stable tetragonal A-LaYSi 2O 7 polymorph at temperatures below 1500°C. This study demonstrates...

Two new white-light (WL)-emitting phosphors (δ-Gd2Si 2O7:Dy and δ-Gd2Si2O 7:Eu,Tb) have been synthesized by the sol-gel method. The Gd-Ln 3+ (Ln3+= Dy3+, Tb3+, Eu 3+) energy-transfer band has been used to excite both phosphors, which provides an enhancement of the Ln3+ emissions. First, WL was generated from δ-Gd2Si2O7:xDy thanks to the...

Although the structures of pure Sc2Si2O7 and Β-Y 2Si 2O 7 have been described in the literature using the C2/m space group, 29Si magic angle spinning (MAS) NMR measurements of the intermediate members of the Sc 2Si 2O 7-Β- Y 2Si 2O 7 system indicate a lowering of the symmetry to the C2 space group. Indeed, these compositions exhibit a unique Si...