Laser and phosphor host La(1-x)MgAl(11+x)0(19)(x = 0.049): Crystal structure at 295K.

The laser and phosphor host material with nominal composition LaMgAl(11)0(19) is shown to be nonstoichiometric. Czochralski grown crystals are hexagonal, with space group P6(3)/mmc, and a = 5.58982(5), C = 21.9738(12)Angstroms at 295K. The thermal expansivity has been determined over the range 295 to 860K: at 295k, alpha(1) = 5.0x10(-6)K(-1) and alpha(3) = 8.1x10(- 6)k(-1). The integrated intensities of 20,487 reflections within a reciprocal sphere of radius (sin theta)/lambda = 1. 0Angstroms(-1) were measured on a CAD-4 diffractometer with MoKalpha radiation, resulting in 18,232 above background. Correction and averaging gave 864 independent structure factors with an internal agreement factor of 0.0145. The crystal structure was solved from the Patterson function and Fourier series and refined by the method of least squares.