Crystal Structure of TbTa3O9and EuTa3O9and Their Continuous Solid Solution Characterization

Crystal Structures and Phase Transitions in A-Site Deficient Perovskites Ln1/3TaO3

“…For example, Yamnova et al 5 reported that Nd 1/3 TaO 3 was tetragonal in P4/mmm with a ) 3.920 and c ) 7.791 Å in contrast to the orthorhombic structure proposed in refs 2-4. Ibarra Polas et al 6 reported the existence of a continuous solid solution in the series Tb 1/3-x Eu x TaO 3 and concluded that the structure evolves from tetragonal in P4/mmm for Tb 1/3 TaO 3 with a ) 3.860 and c ) 7.780 Å to orthorhombic in Pmmm for Eu 1/3 TaO 3 with a ) 3.869, b ) 3.884, and c ) 7.797 Å. Although these authors did not explicitly comment on the nature of the transition between these two structures their published results are suggestive of a first-order transition.…”

Magnetically Controllable Two‐Dimensional Spin Transport in a 3D Crystal

“…The crystal structure of Eu x TaO 3 (shown in Figure 1b) is similar to that of a double perovskite, [ 31–33 ] which has a unit cell composed of two formula units of ABO 3 along the crystalline c ‐axis. However, Eu x TaO 3 alternates between an unoccupied A site and an Eu A site with partial occupancy 2 x , [ 32,34,35 ] hence we name this structure a fractional perovskite.…”

“…The crystal structure of Eu x TaO 3 (shown in Figure 1b) is similar to that of a double perovskite, [ 31–33 ] which has a unit cell composed of two formula units of ABO 3 along the crystalline c ‐axis. However, Eu x TaO 3 alternates between an unoccupied A site and an Eu A site with partial occupancy 2 x , [ 32,34,35 ] hence we name this structure a fractional perovskite. The partial Eu site occupancy results in slight distortions of the two TaO 3 octahedra along the a and b axes, causing oxygen ions at $$(0,b/2,c/2\pm c/4)$$ to shift more significantly along c compared to those at $$(a/2,0,c/2\pm c/4)$$.…”

“…This anisotropic distortion lowers the symmetry of each octahedron to $${D}_{2h}$$, giving rise to an orthorhombic crystal structure with a Pmmm point group symmetry. [ 32,34,35 ] While these orthorhombic distortions are small enough that the system can be well approximated by an idealized tetragonal structure (as discussed later in our toy‐model analysis), we have fully considered them in our ab initio calculations, employing the orthorhombic structural parameters reported by Sirotinkin et al. [ 35 ] with lattice parameters, $$a=b=3.8771\,\hbox{\AA}$$, $$c=7.7960\,\hbox{\AA}$$.…”

“…This anisotropic distortion lowers the symmetry of each octahedron to D 2h , giving rise to an orthorhombic crystal structure with a Pmmm point group symmetry. [32,34,35] While these orthorhombic distortions are small enough that the system can be well approximated by an idealized tetragonal structure (as discussed later in our toy-model analysis), we have fully considered them in our ab initio calculations, employing the orthorhombic structural parameters reported by Sirotinkin et al [35] with lattice parameters, a = b = 3.8771 Å, c = 7.7960 Å. It should be noted that some other X-ray diffraction measurements [32] have reported minor mismatches in lattice parameters a and b but these have little effect on the key features of the system (see Section I, Supporting Information for a comparison between electron structure calculations with and without a ≠ b distortion).…”