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.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access  LD5655.V856_1987.A335.pdf 11.71 Mb 00:54:12 00:27:52 00:24:23 00:12:11 00:01:02 next to an author's name indicates that all files or directories associated with their ETD are accessible from the Virginia Tech campus network only.

If you have questions or technical problems, please Contact DLA.