KLaF4 nanocrystallisation in oxyfluoride glass-ceramics

Abstract

Nanocrystallisation of the cubic and hexagonal polymorphs of KLaF4 in a 70SiO(2)-7Al(2)O(3)-16K(2)O-7LaF(3) (mol%) glass has been achieved by heat treatment above the glass transition temperature. For treatment at 580 degrees C, only the cubic structure crystallises, with a maximum crystallite size of similar to 9 nm. At higher temperatures, crystallisation of the hexagonal structure also takes place. The crystallisation process has been analysed using several thermal and structural techniques and is revealed to occur from a constant number of nuclei. The formation of a viscous barrier which inhibits further crystal growth and limits the crystal size to the nanometric range is observed. The title materials doped with lanthanide ions may be good candidates for optical applications

Effect of lead fluoride incorporation on the structure and luminescence properties of tungsten sodium phosphate glasses

“…Luminescent properties are improved when heavy metal fluoride nanocrystallites are precipitated from the precursor glass matrix since rare earth ions usually migrate to the low phonon energy crystalline phase [15][16][17][18][19][20][21][22][23][24]. However, incorporation of large amounts of heavy metal fluorides is often difficult since its modifier behavior usually highly depolymerizes the glass network with an increasing tendency of the resulting melt to crystallize upon cooling.…”

Upconversion luminescence in erbium doped transparent oxyfluoride glass ceramics containing hexagonal NaYF4 nanocrystals

“…This phenomenon is observed in several oxyfluoride glass ceramics [25], [34][35][36]. However, in this glass system ␤-NaYF 4 is formed before ␣-NaYF 4 .…”

Enhanced emission and spectroscopic properties in oxyfluoride glass ceramics containing LaOF:Er^3+ nanocrystals

“…From the peak width of XRD pattern, the crystalline size of LaOF crystals in the GCs can be calculated on the basis of the Scherrer's equation [16]:…”