RT Journal Article
SR Electronic
T1 Phase Transformations and Metallization of Magnesium Oxide at High Pressure and Temperature
JF Science
JO Science
FD American Association for the Advancement of Science
SP 1330
OP 1333
DO 10.1126/science.1229450
VO 338
IS 6112
A1 McWilliams, R. Stewart
A1 Spaulding, Dylan K.
A1 Eggert, Jon H.
A1 Celliers, Peter M.
A1 Hicks, Damien G.
A1 Smith, Raymond F.
A1 Collins, Gilbert W.
A1 Jeanloz, Raymond
YR 2012
UL http://science.sciencemag.org/content/338/6112/1330.abstract
AB Magnesium oxide (MgO) is representative of the rocky materials comprising the mantles of terrestrial planets, such that its properties at high temperatures and pressures reflect the nature of planetary interiors. Shock-compression experiments on MgO to pressures of 1.4 terapascals (TPa) reveal a sequence of two phase transformations: from B1 (sodium chloride) to B2 (cesium chloride) crystal structures above 0.36 TPa, and from electrically insulating solid to metallic liquid above 0.60 TPa. The transitions exhibit large latent heats that are likely to affect the structure and evolution of super-Earths. Together with data on other oxide liquids, we conclude that magmas deep inside terrestrial planets can be electrically conductive, enabling magnetic field–producing dynamo action within oxide-rich regions and blurring the distinction between planetary mantles and cores.