57 research outputs found
Effect of Ta 2 O 5 , Nb 2 O 5 , and HfO 2 Alloying on the Transformability of Y 2 O 3 -Stabilized Tetragonal ZrO 2
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65528/1/j.1151-2916.1990.tb05100.x.pd
X-ray Absorption Studies of Ceria with Trivalent Dopants
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65899/1/j.1151-2916.1991.tb04328.x.pd
Ab Initio Study of the Structural Phase Transition in Cubic Pb_3GeTe_4
In the substitutionally disordered narrow-gap semiconductor Pb_{1-x}Ge_xTe, a
finite-temperature cubic-rhombohedral transition appears above a critical
concentration . As a first step towards a first-principles
investigation of this transition in the disordered system, a (hypothetical)
ordered cubic Pb_3GeTe_4 supercell is studied. First principles
density-functional calculations of total energies and linear response functions
are performed using the conjugate-gradients method with ab initio
pseudopotentials and a plane-wave basis set. Unstable modes in Pb_3GeTe_4 are
found, dominated by off-centering of the Ge ions coupled with displacements of
their neighboring Te ions. A model Hamiltonian for this system is constructed
using the lattice Wannier function formalism. The parameters for this
Hamiltonian are determined from first principles. The equilibrium
thermodynamics of the model system is studied via Metropolis Monte Carlo
simulations. The calculated transition temperature, T_c, is approximately 620K
for the cubic Pb_3GeTe_4 model, compared to the experimental value of T_c
\approx 350K for disordered Pb_{0.75}Ge_{0.25}Te. Generalization of this
analysis to the disordered Pb_{1-x}Ge_xTe system is discussed.Comment: 38 pages, LaTeX, 11 PostScript figure
Solid-Liquid Reactions in the System Si 3 N 4 –Β-SiAlON–Y 3 Al 5 O 12
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65780/1/j.1151-2916.1994.tb04657.x.pd
Phase Relationships in the ZrO 2 -Sc 2 O 3 and ZrO 2 -In 2 O 3 Systems
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65734/1/j.1151-2916.1993.tb08328.x.pd
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