Structural and spectroscopic study of a single crystal of lanthanum aluminogallate, doped with neodymium

Journal Article · Thu Sep 01 00:00:00 EDT 1988 · J. Solid State Chem.; (United States)

DOI:https://doi.org/10.1016/0022-4596(88)90207-1· OSTI ID:6810484

Kahn, A; LeComte, J; Thery, J; Vivien, D

The structure and optical properties of a neodymium activated lanthanum aluminogallate are described. This compound exhibits a promising laser behavior (5% Nd content, 1.059 and 1.08 ..mu..m fluorescence radiations, average lifetime of the Nd/sup 3 +/ ion excited state about 330 ..mu..s). The Czochralski grown single crystals have a hexagonal magnetoplumbite-like structure with space group P6/sub 3//mmc, Z = 2, a = 5.673(2) A, c = 22.32(1) A and are shown to be nonstoichiometric (final R factor = 0.033, R/sub w/ = 0.038). The composition deduced from the structure refinement of the studied crystal is La/sub 0.84/Nd/sub 0.04/Mg/sub 0.64/Al/sub 5.27/Ga/sub 6.13/O/sub 19/. Aluminum and gallium are not randomly distributed on the available sites of the structure; Gas is rather found on tetrahedral or pseudo-tetrahedral sites, whereas Al is mainly sixfold coordinated. This has an effect on Nd/sup 3 +/ crystal field by increasing the Ln-Ln distances. The Ln deficiency (approx. 0.9 instead of 1) is balanced by excess Al. Ln(La + Nd) is split on two sites with different local symmetry. This is suggested by the X-ray structural investigation and confirmed by V-UV absorption and ESR spectroscopy, which reveal the occupation of both an axial 2d site (D/sub 3h/, about 80%) and a nonaxial satellite 6h position (C/sub 2v/, about 10%). This is consistent with previous results obtained for hexaaluminates and hexagallates.

• Research Organization: CNRS, Paris (France)
• OSTI ID: 6810484
• Journal Information: J. Solid State Chem.; (United States), Vol. 76:1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM COMPOUNDS
CRYSTAL STRUCTURE
GALLIUM OXIDES
LANTHANUM COMPOUNDS
NEODYMIUM COMPOUNDS
CATIONS
CRYSTAL GROWTH
ELECTRON SPIN RESONANCE
EXPERIMENTAL DATA
HEXAGONAL LATTICES
MONOCRYSTALS
NEODYMIUM ADDITIONS
NMR SPECTRA
SPACE GROUPS
ALLOYS
CHALCOGENIDES
CHARGED PARTICLES
CRYSTAL LATTICES
CRYSTALS
DATA
GALLIUM COMPOUNDS
INFORMATION
IONS
MAGNETIC RESONANCE
NEODYMIUM ALLOYS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
RARE EARTH ADDITIONS
RARE EARTH ALLOYS
RARE EARTH COMPOUNDS
RESONANCE
SPECTRA
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies
360204 - Ceramics
Cermets
& Refractories- Physical Properties