The effect of the chemical substitution of Ti, Zr, and Gd cations on the structure and properties of bismuth-based pyrochlores was investigated for (Bi1.5Zn1.0Nb1.5)O7 and Bi2(Zn2/3Nb4/3)O7. Broad ranges of solid solutions based on cubic (Bi1.5Zn1.0Nb1.5)O7 were observed for Ti and Zr cations: (Bi1.5Zn12(x/3)Nb1.52(2x/3)Zrx)O7 (0.0 < x < 1.5) and (Bi1.5Zn12(x/3)Nb1.52(2x/3)Tix)O7 (0.0 < x < 2.2...

A new class of materials termed topological insulators have been intensively investigated due to their unique Dirac surface state carrying dissipationless edge spin currents. Recently, it has been theoretically proposed that the three dimensional analogue of this type of band structure, the Weyl Semimetal phase, is materialized in pyrochlore oxides with strong spin-orbit coupling, accompanied b...

Thermodynamic quantities and correlation functions (CFs) of the classical antiferromagnet on the checkerboard lattice are studied for the exactly solvable infinite-component spin-vector model, D → ∞. In contrast to conventional two-dimensional magnets with continuous symmetry showing extended short-range order at distances smaller than the correlation length, r ∼ ξc ∝ exp(T /T ), correlations i...

Quantum mechanics states that hopping integral between local orbitals makes the energy band dispersive. However, in some special cases, there are bands with no dispersion due to quantum interference. These bands are called as flat band. Many models having flat band have been proposed, and many interesting physical properties are predicted. However, no real compound having flat band has been fou...

There is interest in identifying novel materials for use in radioactive waste applications and studying their behavior under high pressure conditions. The mineral zirconolite (CaZrTi(2)O(7)) exists naturally in trace amounts in diamond-bearing deep-seated metamorphic/igneous environments, and it is also identified as a potential ceramic phase for radionuclide sequestration. However, it has been...

In this paper, the properties of photonic band gaps (PBGs) for three-dimensional (3D) photonic crystals (PCs) composed of isotropic positive-index materials and epsilon-negative materials with pyrochlore lattices are theoretically investigated by a modified plane wave expansion method. The eigenvalue equations of calculating the band structures for such 3D PCs in the first irreducible Brillouin...

This article reviews recent achievements on the crystal growth of a new series of pyrochlore oxides—lanthanide zirconates, which are frustrated magnets with exotic magnetic properties. Oxides of the type A2B2O7 (where A “ Rare Earth, B “ Ti, Mo) have been successfully synthesised in single crystal form using the floating zone method. The main difficulty of employing this technique for the growt...