data_global
_chemical_name_mineral 'Fresnoite'
loop_
_publ_author_name
'Chukanov N V'
'Kazheva O N'
'Fischer R X'
'Aksenov S M'
_journal_name_full 'Acta Crystallographica, Section B'
_journal_volume 79 
_journal_year 2023
_journal_page_first 
_journal_page_last S2052520622012045
_publ_section_title
;
 Refinement of the crystal structure of fresnoite, Ba2TiSi2O8, from Lohley
 (Eifel district, Germany); Gladstone-Dale compatibility, electronic polarizability
 and vibrational spectroscopy of minerals and inorganic compounds with
 pentacoordinated TiIV and a titanyl bond
;
_database_code_amcsd 0021205
_chemical_compound_source 'Lohley, Eifel district, Germany'
_chemical_formula_sum 'Ba2 Ti Si2 O8'
_cell_length_a 8.5104
_cell_length_b 8.5104
_cell_length_c 5.1975
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 376.439
_exptl_crystal_density_diffrn      4.470
_symmetry_space_group_name_H-M 'P 4 b m'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '1/2-y,1/2-x,z'
  '-y,x,z'
  '1/2+x,1/2-y,z'
  '-x,-y,z'
  '1/2+y,1/2+x,z'
  'y,-x,z'
  '1/2-x,1/2+y,z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_U_iso_or_equiv
Ba   0.32715   0.82715   0.00051   0.00865
Ti   0.00000   0.00000   0.53608   0.00667
Si   0.12793   0.62793   0.51300   0.00767
O1   0.00000   0.00000   0.21060   0.01490
O2   0.00000   0.50000   0.63000   0.02500
O3   0.12600   0.62600   0.20670   0.00880
O4   0.29220   0.57610   0.64510   0.02360
loop_
_atom_site_aniso_label
_atom_site_aniso_U_11
_atom_site_aniso_U_22
_atom_site_aniso_U_33
_atom_site_aniso_U_12
_atom_site_aniso_U_13
_atom_site_aniso_U_23
Ba 0.00940 0.00940 0.00715 -0.00491 -0.00086 -0.00086
Ti 0.00710 0.00710 0.00570 0.00000 0.00000 0.00000
Si 0.00870 0.00870 0.00550 0.00130 -0.00130 -0.00130
O1 0.01780 0.01780 0.00910 0.00000 0.00000 0.00000
O2 0.03500 0.03500 0.00560 -0.02200 0.00000 0.00000
O3 0.00980 0.00980 0.00670 -0.00130 -0.00020 -0.00020
O4 0.01420 0.04620 0.01050 0.01500 -0.00350 -0.00750