The compound described by Er2TiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(3), two equivalent O(1), and three equivalent O(4) atoms to form distorted ErO6 octahedra that share corners with two equivalent Er(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, edges with two equivalent Er(2)O6 octahedra, and edges with four equivalent Er(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-65°. In the second Er site, Er(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form ErO6 octahedra that share corners with two equivalent Er(1)O6 octahedra, corners with two equivalent Er(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, edges with two equivalent Er(1)O6 octahedra, and edges with two equivalent Er(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-64°. Ti(1) is bonded to one O(3), one O(4), one O(5), and three equivalent O(2) atoms to form distorted TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Er(1)O6 octahedra, corners with four equivalent Er(2)O6 octahedra, and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-65°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Er(1) and two equivalent Er(2) atoms to form OEr4 tetrahedra that share corners with two equivalent O(3)Er3Ti tetrahedra, corners with four equivalent O(4)Er3Ti tetrahedra, corners with four equivalent O(1)Er4 tetrahedra,  an edgeedge with one O(4)Er3Ti tetrahedra, and edges with two equivalent O(3)Er3Ti tetrahedra. In the second O site, O(2) is bonded in a 3-coordinate geometry to three equivalent Ti(1) atoms. In the third O site, O(3) is bonded to one Er(1), two equivalent Er(2), and one Ti(1) atom to form OEr3Ti tetrahedra that share corners with two equivalent O(3)Er3Ti tetrahedra, corners with two equivalent O(1)Er4 tetrahedra, corners with four equivalent O(4)Er3Ti tetrahedra, and edges with two equivalent O(1)Er4 tetrahedra. In the fourth O site, O(4) is bonded to three equivalent Er(1) and one Ti(1) atom to form OEr3Ti tetrahedra that share corners with two equivalent O(4)Er3Ti tetrahedra, corners with four equivalent O(3)Er3Ti tetrahedra, corners with four equivalent O(1)Er4 tetrahedra,  an edgeedge with one O(1)Er4 tetrahedra, and edges with two equivalent O(4)Er3Ti tetrahedra. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Er(2) and one Ti(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Er2TiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.608
_cell_length_b   7.450
_cell_length_c   15.438
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   414.942
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Er  Er0  1  0.250  0.101  0.084  1.0
  Er  Er1  1  0.250  0.162  0.737  1.0
  Er  Er2  1  0.750  0.338  0.237  1.0
  Er  Er3  1  0.750  0.399  0.584  1.0
  Er  Er4  1  0.250  0.601  0.416  1.0
  Er  Er5  1  0.250  0.662  0.763  1.0
  Er  Er6  1  0.750  0.838  0.263  1.0
  Er  Er7  1  0.750  0.899  0.916  1.0
  Ti  Ti8  1  0.250  0.114  0.423  1.0
  Ti  Ti9  1  0.750  0.386  0.923  1.0
  Ti  Ti10  1  0.250  0.614  0.077  1.0
  Ti  Ti11  1  0.750  0.886  0.577  1.0
  O  O12  1  0.750  0.069  0.174  1.0
  O  O13  1  0.750  0.074  0.453  1.0
  O  O14  1  0.750  0.122  0.648  1.0
  O  O15  1  0.750  0.157  0.995  1.0
  O  O16  1  0.250  0.246  0.322  1.0
  O  O17  1  0.750  0.254  0.822  1.0
  O  O18  1  0.250  0.343  0.495  1.0
  O  O19  1  0.250  0.378  0.148  1.0
  O  O20  1  0.250  0.426  0.953  1.0
  O  O21  1  0.250  0.431  0.674  1.0
  O  O22  1  0.750  0.569  0.326  1.0
  O  O23  1  0.750  0.574  0.047  1.0
  O  O24  1  0.750  0.622  0.852  1.0
  O  O25  1  0.750  0.657  0.505  1.0
  O  O26  1  0.250  0.746  0.178  1.0
  O  O27  1  0.750  0.754  0.678  1.0
  O  O28  1  0.250  0.843  0.005  1.0
  O  O29  1  0.250  0.878  0.352  1.0
  O  O30  1  0.250  0.926  0.547  1.0
  O  O31  1  0.250  0.931  0.826  1.0
[/CIF]
.
The compound described by Er2TiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(3), two equivalent O(1), and three equivalent O(4) atoms to form distorted ErO6 octahedra that share corners with two equivalent Er(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, edges with two equivalent Er(2)O6 octahedra, and edges with four equivalent Er(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-65°. In the second Er site, Er(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form ErO6 octahedra that share corners with two equivalent Er(1)O6 octahedra, corners with two equivalent Er(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, edges with two equivalent Er(1)O6 octahedra, and edges with two equivalent Er(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-64°. Ti(1) is bonded to one O(3), one O(4), one O(5), and three equivalent O(2) atoms to form distorted TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Er(1)O6 octahedra, corners with four equivalent Er(2)O6 octahedra, and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-65°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Er(1) and two equivalent Er(2) atoms to form OEr4 tetrahedra that share corners with two equivalent O(3)Er3Ti tetrahedra, corners with four equivalent O(4)Er3Ti tetrahedra, corners with four equivalent O(1)Er4 tetrahedra,  an edgeedge with one O(4)Er3Ti tetrahedra, and edges with two equivalent O(3)Er3Ti tetrahedra. In the second O site, O(2) is bonded in a 3-coordinate geometry to three equivalent Ti(1) atoms. In the third O site, O(3) is bonded to one Er(1), two equivalent Er(2), and one Ti(1) atom to form OEr3Ti tetrahedra that share corners with two equivalent O(3)Er3Ti tetrahedra, corners with two equivalent O(1)Er4 tetrahedra, corners with four equivalent O(4)Er3Ti tetrahedra, and edges with two equivalent O(1)Er4 tetrahedra. In the fourth O site, O(4) is bonded to three equivalent Er(1) and one Ti(1) atom to form OEr3Ti tetrahedra that share corners with two equivalent O(4)Er3Ti tetrahedra, corners with four equivalent O(3)Er3Ti tetrahedra, corners with four equivalent O(1)Er4 tetrahedra,  an edgeedge with one O(1)Er4 tetrahedra, and edges with two equivalent O(4)Er3Ti tetrahedra. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Er(2) and one Ti(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Er2TiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.608
_cell_length_b   7.450
_cell_length_c   15.438
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   414.942
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Er  Er0  1  0.250  0.101  0.084  1.0
  Er  Er1  1  0.250  0.162  0.737  1.0
  Er  Er2  1  0.750  0.338  0.237  1.0
  Er  Er3  1  0.750  0.399  0.584  1.0
  Er  Er4  1  0.250  0.601  0.416  1.0
  Er  Er5  1  0.250  0.662  0.763  1.0
  Er  Er6  1  0.750  0.838  0.263  1.0
  Er  Er7  1  0.750  0.899  0.916  1.0
  Ti  Ti8  1  0.250  0.114  0.423  1.0
  Ti  Ti9  1  0.750  0.386  0.923  1.0
  Ti  Ti10  1  0.250  0.614  0.077  1.0
  Ti  Ti11  1  0.750  0.886  0.577  1.0
  O  O12  1  0.750  0.069  0.174  1.0
  O  O13  1  0.750  0.074  0.453  1.0
  O  O14  1  0.750  0.122  0.648  1.0
  O  O15  1  0.750  0.157  0.995  1.0
  O  O16  1  0.250  0.246  0.322  1.0
  O  O17  1  0.750  0.254  0.822  1.0
  O  O18  1  0.250  0.343  0.495  1.0
  O  O19  1  0.250  0.378  0.148  1.0
  O  O20  1  0.250  0.426  0.953  1.0
  O  O21  1  0.250  0.431  0.674  1.0
  O  O22  1  0.750  0.569  0.326  1.0
  O  O23  1  0.750  0.574  0.047  1.0
  O  O24  1  0.750  0.622  0.852  1.0
  O  O25  1  0.750  0.657  0.505  1.0
  O  O26  1  0.250  0.746  0.178  1.0
  O  O27  1  0.750  0.754  0.678  1.0
  O  O28  1  0.250  0.843  0.005  1.0
  O  O29  1  0.250  0.878  0.352  1.0
  O  O30  1  0.250  0.926  0.547  1.0
  O  O31  1  0.250  0.931  0.826  1.0
[/CIF]
.