The structure and ion-conducting properties of the defect-fluorite ring structure formed around amorphous ion-tracks by swift heavy ion irradiation of Gd2Ti2O7 pyrochlore are investigated. High angle annular dark field imaging complemented with ion-track molecular dynamics simulations show that the atoms in the ring structure are disordered, and have relatively larger cation-cation interspacing...

We study the phase diagram of two models of spin-1 /2 antiferromagnets composed of corner-sharing tetrahedra, the basis of the pyrochlore structure. Primarily, we focus on the Heisenberg antiferromaget on the checkerboard lattice also called the planar pyrochlore and crossed-chain model . This model has an anisotropic limit, when the dimensionless ratio of two exchange constants J /J 1, in whic...

where t is the transfer integral for nearest-neighbor sites hiji on the pyrochlore lattice, JH represents the Hund’s-rule coupling between the itinerant electron spin ~si and the localized spin ~ Si, while JAF is the super-exchange antiferromagnetic interaction between the neighboring localized spins. The first two terms induce the double-exchange ferromagnetic interactions through the kinetic ...

Employing large-scale quantum Monte Carlo simulations, we reveal the full phase diagram of the extended Hubbard model of hard-core bosons on the pyrochlore lattice with partial fillings. When the intersite repulsion is dominant, the system is in a cluster Mott insulator phase with an integer number of bosons localized inside the tetrahedral units of the pyrochlore lattice. We show that the full...

The minerals of the pyrochlore group exhibit a large range of chemical composition. The general structural formula can be written as A2–mB2X6–wY1–n•pH2O. The occupancy of the eight-fold-coordinated A site can reflect the degree of alteration of the pyrochlore. In unaltered pyrochlore-group minerals, this site is completely filled by Na and Ca, whereas in the altered equivalents, the A site is o...

A facile and template-free reverse micelle-based method can be employed to synthesize highly crystalline and pure stoichiometric bismuth titanate (Bi(2)Ti(2)O(7)) pyrochlore nanorods 400-500 nm long and 40-50 nm in diameter which demonstrate promising photoactivity.

Understanding and predicting radiation damage evolution in complex materials is crucial for developing next-generation nuclear energy sources. Here, using a combination of ion beam irradiation, transmission electron microscopy and X-ray diffraction, we show that, contrary to the behaviour observed in pyrochlores, the amorphization resistance of spinel compounds correlates directly with the ener...

The photonic band diagrams of close-packed colloidal diamond and pyrochlore structures, have been studied using Korringa-Kohn-Rostoker (KKR) and plane-wave calculations. In addition, the occurrence of a band gap has been investigated for the binary Laves structures and their constituent large- and small-sphere substructures. It was recently shown that these Laves structures give the possibility...

We demonstrate the existence of an orbital Coulomb phase as the exact ground state of a p-orbital exchange Hamiltonian on the diamond lattice. The Coulomb phase is an emergent state characterized by algebraic dipolar correlations and a gauge structure resulting from local constraints (ice rules) of the underlying lattice models. For most ice models on the pyrochlore lattice, these local constra...

I consider the class of “depleted pyrochlore” lattices of corner-sharing triangles, made by removing spins from a pyrochlore lattice such that every tetrahedron loses exactly one. Previously known examples are the “hyperkagome” and “kagome staircase”. I give criteria in terms of loops for whether a given depleted lattice can order analogous to the kagome “ √ 3× √ 3” state, and also show how the...