TY - JOUR

T1 - Chemically Induced Polytypic Phase Transitions in the Mg[(UO2)(TO4)2(H2O)](H2O)4 (T = S, Se) System

AU - Gurzhiy, Vladislav V.

AU - Tyumentseva, Olga S.

AU - Izatulina, Alina R.

AU - Krivovichev, Sergey V.

AU - Tananaev, Ivan G.

PY - 2019/11/4

Y1 - 2019/11/4

N2 - Chemically induced polytypic phase transitions have been observed during experimental investigations of crystallization in the mixed uranyl sulfate-selenate Mg[(UO2)(TO4)2(H2O)](H2O)4 (T = S, Se) system. Three different structure types form in the system, depending upon the Se:S ratio in the initial aqueous solution. The phases with the Se/(Se + S) ratios (in mol %) in the ranges 0-9, 16-47, and 58-100 crystallize in the space groups P21, Pmn21, and P21/c, respectively. The structures of the phases are based upon the same type of uranyl-based sulfate/selenate chains that, through hydrogen bonds, are linked into pseudolayers of the same topological type. The layers are linked into three-dimensional structures via interlayer Mg-centered octahedra. The three structure types contain the same layers but with different stacking sequences that can be conveniently described as belonging to the 1M, 2O, and 2M polytypic modifications. The Se-for-S substitution demonstrates a strong selectivity with preferential incorporation of Se into less tightly bonded T1 site. The larger ionic radius of Se6+ relative to S6+ induces rotation of (T1O4) tetrahedra in the adjacent layers and reconstruction of the structure types. From the information-theoretic viewpoint, the intermediate Pmn21 structure type is more complex than the monoclinic end-member structure types.

AB - Chemically induced polytypic phase transitions have been observed during experimental investigations of crystallization in the mixed uranyl sulfate-selenate Mg[(UO2)(TO4)2(H2O)](H2O)4 (T = S, Se) system. Three different structure types form in the system, depending upon the Se:S ratio in the initial aqueous solution. The phases with the Se/(Se + S) ratios (in mol %) in the ranges 0-9, 16-47, and 58-100 crystallize in the space groups P21, Pmn21, and P21/c, respectively. The structures of the phases are based upon the same type of uranyl-based sulfate/selenate chains that, through hydrogen bonds, are linked into pseudolayers of the same topological type. The layers are linked into three-dimensional structures via interlayer Mg-centered octahedra. The three structure types contain the same layers but with different stacking sequences that can be conveniently described as belonging to the 1M, 2O, and 2M polytypic modifications. The Se-for-S substitution demonstrates a strong selectivity with preferential incorporation of Se into less tightly bonded T1 site. The larger ionic radius of Se6+ relative to S6+ induces rotation of (T1O4) tetrahedra in the adjacent layers and reconstruction of the structure types. From the information-theoretic viewpoint, the intermediate Pmn21 structure type is more complex than the monoclinic end-member structure types.

UR - http://www.scopus.com/inward/record.url?scp=85074225564&partnerID=8YFLogxK

U2 - 10.1021/acs.inorgchem.9b02454

DO - 10.1021/acs.inorgchem.9b02454

M3 - Article

C2 - 31647660

AN - SCOPUS:85074225564

VL - 58

SP - 14760−14768

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 21

ER -