Crystal chemistry and physical properties of the A2M3(H2O)2[B4P6O24(OH)2](A = Cs, Rb; M = Ni, Cu, (Ni, Fe)) borophosphate familyстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 24 июля 2019 г.
Аннотация:Three new transition metal borophosphates, Cs2Cu3(H2O)2[B4P6O24(OH)2] (denoted (I)), Cs2Ni3(H2O)2[B4P6O24(OH)2] (II) and
mixed Rb2Ni2.5Fe0.5(H2O)2[B4P6O24(OH)2](III) were synthesized from boric acid flux at 473-493 K. X-ray single-crystal
diffraction study confirms their isotipy with (Cs/Rb)2Co3(H2O)2[B4P6O24(OH)2] borophosphates crystallizing in the
orthorombic space group Pbca. The crystal structures of all compounds are based on 3D frameworks made from
corrugating borophosphate layers [B4P6O24(ОН)2] and trimers of MO4(H2O)2 and two MO6 edge-sharing octahedra. The
negative charge of the framework is compensated by alkali metal cations, Rb+
or Cs+
. Structural analysis reveals the
flexibility of mixed anionic frameworks of described structural type. The Cu-member demonstrates a strong distortion of
the units cell due to the Jahn-Teller effect of the d9
configuration of Cu2+ cation. The possibility of solid solution between
different transition metals (Fe, Ni) with formation of crystals with mixed structural positions is confirmed by an example of
(III) phase. It is shown, that Fe2+ cations prefer to occupy the M2 position with more distorted oxygen enviroment, as
compared to the M1O6 octahedra. Magnetic studies of (I), (II) and (III) prove that all compounds are paramagnets down to
lowest temperatures of measurements, 2 K. (I) and (II) compounds are thermally stable up to 500°C. Different mechanisms
of their thermal decomposition are discussed. The possibility of a wide isomorphous substitution at the transition metal
sites of the title structure type opens the way to properties’ modification in the discussed series of borophosphates.