Lattice Vibrations in BiLiF₄ and YLiF₄

Abstract

Results of Raman studies of BiLiF, and YLiF, single crystals at 300, 77, and 4.2 K and powder pellets of these materials at 300 K are reported. The observed vibrations are assigned to the irreducible representations of the space group of the crystals. Es werden Ergebnisse von Rarnanuntersuchungen an BiLiF,-und YLiF,-Einkristallen bei 300, 77 und 4,2 K und an PulverpreBlingen dieser Materialien bei 300 K mitgeteilt. Die beobachteten Schwingnngen werden irreduziblen Darstellungen der Raumgruppe dieser Kristalle zngeordnet.1) Heinrich-Buff-Ring 16, D-6300 GieBen, FRG. 2) Part I of Thesis (D26).

Growth and characterization of LiYF4:Nd single crystal fibres for optical applications

“…The samples show similar Raman spectra, so their structural qualities are comparable. All peaks are assigned to the LiYF 4 structure symmetry [18,19]. Some peaks were not detected comparing with those identified in the literature due to the polarization lack and noise level.…”

LLE Review Quarterly Report (January-March 2002). Volume 90

“…Many models have been proposed, ranging from those involving specific defects and molecular compounds to those involving quantum confinement. [12][13][14][15][16]25 Of all these models, two have received strong experimental support. The "pure" quantum confinement originally proposed by Canham,8 which is consistent with many observations, has recently received support from resonant photoluminescence experiment^.^^,^^ In these experiments the low-temperature luminescence was not excited by a shortwavelength laser but by a laser tuned inside the broad PL spectrum to provide size-selective excitation.…”

“…It must be noted that neither Canham's model for the luminescence nor Lehmann and Gosele's model for pore formation is universally accepted, and other models have been proposed. [12][13][14][15][16] Note also that the nanostructure of porous silicon is quite complicated. Even though columnar crystalline structures are present in some samples, the shape, thickness, and orientation of these columns or wires are not uniform.…”

LLE Review Quarterly Report (January-March 2001). Volume 86

“…Many models have been proposed, ranging from those involving specific defects and molecular compounds to those involving quantum confinement. [12][13][14][15][16]25 Of all these models, two have received strong experimental support. The "pure" quantum confinement originally proposed by Canham,8 which is consistent with many observations, has recently received support from resonant photoluminescence experiment^.^^,^^ In these experiments the low-temperature luminescence was not excited by a shortwavelength laser but by a laser tuned inside the broad PL spectrum to provide size-selective excitation.…”