Title page for ETD etd-02062013-040123


Type of Document Dissertation
Author Affholter, Kathleen
URN etd-02062013-040123
Title Synthesis and crystal chemistry of lanthanide allanites
Degree PhD
Department Geological Sciences
Advisory Committee
Advisor Name Title
Hewitt, David A. Committee Chair
Bloss, F. Donald Committee Member
Gibbs, Gerald V. Committee Member
Ribbe, Paul H. Committee Member
Speer, J. Alex Committee Member
Keywords
  • Allanite
Date of Defense 1987-12-15
Availability restricted
Abstract

Metamictization and complex chemistry are major obstacles to the crystal chemical characterization of natural allanites. To overcome these problems, allanites, Ca(REE)Fe2+AlzSi3O12(OH), where REE = La, La-Ce, Ce, Nd, Sm, Eu, Gd, Er, Dy, Yb and Y have been synthesized hydrothermally from unbuffered and buffered oxide mixes at 500 to 650°C, 5.5 kbar (550 MPa), and 700 to 725°C, 4 kbar (400 MPa). Although allanite is readily synthesized, high yields are obtained only for allanite-(LREE) compositions, and end—member composition is obtained only for allanite-(La). Er and Yb ions are too small to substitute at the A(2) site in allanite, but a small amount can substitute at the VI~coordinated M(3) site. Fe2+ in the M(3) site favors LREE substitution, which supports the contention that allanite is Ce—selective.

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