Structural and spectroscopic studies on trimorphous MeNH3GeCl3

1H NMR study of internal motions and quantum rotational tunneling in (CH3)4NGeCl3

“…[4] In addition to the deviation from spherical symmetry, additional symmetry elements may lead to increased reorientation motions. [5] In alkylammonium trichlorogermanate (II) compounds, mobile chloride ion is found to be responsible for ionic conductivity and its abrupt change at the phase transitions. [6,7] Möller and Felsche.…”

Study of molecular reorientation and quantum rotational tunneling in tetramethylammonium selenate by 1H NMR

“…Successive replacement of hydrogen by CH 3 groups in ammonium ion according to the formula (CH 3 ) x NH 4Àx (x ¼ 1, y, 4), leads to a cation with a larger ionic radius, which may result in strong phase transitions due to changes in symmetry as well as the tolerance factor [2]. Substitution of the CH 3 leads to additional symmetry elements and hence increased reorientation motions [3]. Tetramethylammonium (TMA) metal salts are known to exhibit phase transitions, hindered reorientational motion of the symmetry groups like CH 3 as well as whole cation (CH 3 ) 4 N and quantum rotational tunneling of the CH 3 groups.…”

Tolerance Factors Revisited: Geometrically Designing the Ideal Environment for Perovskite Dopants

“…In past experimental work, substitution at the A, B, and X sites has demonstrated ways to tune band gaps throughout the visible spectrum. − Relevant to this paper, the B-site replacement of lead with germanium is desirable in the push toward lead-free perovskite light absorbers . While there exist a number of distorted germanium halide perovskites, − the inclusion of germanium in perovskite photovoltaics remains underexplored.…”