Elasticity of αCristobalite: A Silicon Dioxide with a Negative Poisson's Ratio
Abstract
Laser Brillouin spectroscopy was used to determine the adiabatic singlecrystal elastic stiffness coefficients of silicon dioxide (SiO_2) in the αcristobalite structure. This SiO_2 polymorph, unlike other silicas and silicates, exhibits a negative Poisson's ratio; αcristobalite contracts laterally when compressed and expands laterally when stretched. Tensorial analysis of the elastic coefficients shows that Poisson's ratio reaches a maximum value of 0.5 in some directions, whereas averaged values for the singlephased aggregate yield a Poisson's ratio of 0.16.
 Publication:

Science
 Pub Date:
 July 1992
 DOI:
 10.1126/science.257.5070.650
 Bibcode:
 1992Sci...257..650Y