Abstract
To understand the origin of the spin-glass state in molybdate pyrochlores, the structure of
Tb2Mo2O7 is investigated using two techniques: the long-range lattice structure was measured using
neutron powder diffraction (NPD), and the local structure information was obtained from extended
x-ray absorption fine structure (EXAFS) measurements. While the long-range structure appears
well ordered, apart from some enhanced mean-squared site displacements, the local structure
measurements indicate nearest-neighbor disorder exists, similar to that found in the related spinglass
pyrochlore, Y2Mo2O7. Although the freezing temperature in Tb2Mo2O7, 25 K, is slightly
higher than in Y2Mo2O7, 22 K, the degree of local bond disorder is actually less in Tb2Mo2O7.
This apparaent contradiction is considered in light of the interactions involved in the freezing
process.
