Ordering processes in Ln2TiO5 (Ln=Dy–Lu): The role of thermal history

Study of bulk and grain-boundary conductivity of Ln2+xHf2−xO7−δ (Ln = Sm-Gd; x = 0, 0.096) pyrochlores

“…The coordination number of the Gd cations near the anti-phase boundaries was assumed to be below 8, in contrast to the octahedral coordination of lanthanides in the pyrochlore structure [13]. Last investigations of titanates Ln 2 TiO 5 (pyrochlore structure) show that the low intensity of the pyrochlore superstructure reflections is due to the small size of pyrochlore microdomains embedded in fluorite matrix [14]. The possibility of the observation of that microdomain stucture by electron microscopy often has limited by technical level of the electron microscope type.…”

“…6 4+ = 0.72Å; R Hf c.n. 6 4+ = 0.71Å), Hf-O bonds are more covalent than Zr-O because Hf has a filled 4f 14 shell, which ensures a more significant overlap of electron orbitals by virtue of its structure. As a result, the hafnates are less prone to defect formation and have significantly lower oxygen ion conductivity than do the zirconates [5].…”

Crystal structure and partial Ising-like magnetic ordering of orthorhombicDy2TiO5

“…where (2) and √ (3) in which K represents a scale factor, m the multiplicity of reflection, F hk 2 the magnetic structure factor, the spin-spin correlation length, and the centroid of the diffuse peak. The integral in F(a) was evaluated numerically and agrees with values reported in ref.…”

“…Insulators of general formula A 2 TiO 5 have attracted significant attention in recent years due to their structural and chemical diversity. Depending on the A-site cation size and/or sample synthesis method, these complex oxides can form cubic, orthorhombic, hexagonal, and monoclinic polymorphs without altering the stoichiometry [1][2][3][4][5]. As a result, these materials are suitable for a wide array of technological applications including potential actinide hosts for longterm storage in a geological repository [6][7][8], ion conductors for fuel cells and oxygen sensors [2], and nanoparticles in oxide dispersion strengthened (ODS) steels [9].…”

Structure and emission properties of glass‐ceramics containing (Eu,Yb)2TiO5 nanocrystals

“…Low phonon energies, large solubility of rare‐earth ions, large refractive indices, along with the thermal stability and robust mechanical properties, make these crystals very promising for optical applications. In addition, optical properties of rare‐earth ions can be further tuned through structural modulation of crystals since their structures can be changed from pyrochlore to disordered pyrochlore and defect‐fluorite structure depending on the relative size of lanthanide ions and titanium ions, concentration, and thermal history . These particular properties have triggered intense research on the nanocrystals or powders through sol‐gel routes and molten salt route, and efficient visible and near‐infrared emission have been reported .…”