These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Pressure-induced changes in the compression mechanism of aluminous perovskite in the Earth's mantle.
    Author: Brodholt JP.
    Journal: Nature; 2000 Oct 05; 407(6804):620-2. PubMed ID: 11034208.
    Abstract:
    Although aluminium is the fifth most abundant element in the Earth's mantle, its effect on the physical properties of perovskite, the main mineral phase in the lower mantle, has largely been ignored. It is becoming clear, however, that many properties of MgSiO3 perovskites are remarkably sensitive to small amounts of aluminium. In particular, perovskite with only 5 wt% Al2O3 has a bulk modulus 10% lower than that of the pure magnesian end-member. The increased compressibility may be due to the high concentrations of oxygen vacancies required to balance the charge of the aluminium; if so, this would have important consequences for the mantle, as aluminous perovskites could be weaker, have lower seismic velocities and be hosts for water. To test whether oxygen vacancies exist in aluminous perovskites, I have calculated the compressibility of end-member defect-bearing perovskites using ab initio methods. The results show that perovskites with oxygen vacancies do have significantly greater compressibilities than those without such vacancies. But the results also suggest that oxygen vacancies become unfavourable at high pressures, in which case only the physical properties of the shallow lower mantle would be affected by aluminium-with the deeper mantle retaining properties similar to those of aluminium-free perovskite.
    [Abstract] [Full Text] [Related] [New Search]