title: Elasticity of agr-Cristobalite: A Silicon Dioxide with a Negative Poisson's Ratio.
abstract: Laser Brillouin spectroscopy was used to determine the adiabatic single-crystal elastic stiffness coefficients of silicon dioxide (SiO(2)) in the alpha-cristobalite structure. This SiO(2) polymorph, unlike other silicas and silicates, exhibits a negative Poisson's ratio; alpha-cristobalite 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 single-phased aggregate yield a Poisson's ratio of -0.16.
authors.forename: A
authors.initials: A
authors.lastname: Yeganeh-Haeri
authors.forename: D J
authors.initials: DJ
authors.lastname: Weidner
authors.forename: J B
authors.initials: JB
authors.lastname: Parise