Structural birefringence in glass in the system Li2O ? Al2O3 ? SiO2

1966 ◽  
Vol 22 (7) ◽  
pp. 435-436 ◽  
Author(s):  
N. I. Ananich ◽  
O. K. Botvinkin ◽  
L. V. Dyatlova
Keyword(s):  
Structural Birefringence

hcp-Argoneinkristalle: Zucht und Messung der Doppelbrechung

1971 ◽  
Vol 26 (3) ◽  
pp. 419-422 ◽  
Author(s):  
W. Hagele ◽  
W. Probst ◽  
K. Dellian ◽  
J. Hingsammer ◽  
E. Lüscher
Keyword(s):  
Crystal Structure ◽  
Neutron Scattering ◽  
Single Crystal ◽  
Single Crystals ◽  
X Ray ◽  
Hcp Structure ◽  
Structural Birefringence ◽  
The Ideal

Abstract A procedure for growing hcp argon single crystals doped with oxygen is described. The hcp crystal structure is confirmed by birefingence and neutron scattering experiments. The birefringence at 77 °K of a hcp argon single crystal doped with 2% oxygen is determined to be ne-n0 = + (2.11 ± 0.63) · 10-6. From this result one can calculate the Lorentz field factors, obtaining fo = (333 328.6 ± 1.4) · 10-6 and fe = (333 342.7 ± 2.8) · 10-8. Using Ewald's theory of structural birefringence to determine σ = c/a from the measured birefringence yields σ = (163 451 ± 3) · 10-5. This value definitely excludes the ideal hcp structure (σ = 1.63299), in contrast with the results of X-ray measurements.

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