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Low‐temperature phase transition and magnetic properties of K 3 YbSi 2 O 7
Author(s) -
Dabić Predrag,
Kahlenberg Volker,
Krüger Biljana,
Rodić Marko,
Kovač Sabina,
Blanuša Jovan,
Jagličić Zvonko,
Karanović Ljiljana,
Petříček Václav,
Kremenović Aleksandar
Publication year - 2021
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520621006077
Subject(s) - crystallography , isostructural , octahedron , orthorhombic crystal system , materials science , paramagnetism , space group , phase transition , crystal structure , chemistry , x ray crystallography , diffraction , condensed matter physics , physics , optics
The new ambient‐temperature hexagonal (space group P 6 3 /mmc ) polymorph of tripotassium ytterbium(III) disilicate (β‐K 3 YbSi 2 O 7 ) has been synthesized by the high‐temperature flux method and subsequently structurally characterized. In the course of the temperature‐dependent single‐crystal diffraction experiments, a phase transformation of β‐K 3 YbSi 2 O 7 to a novel low‐temperature orthorhombic phase (β′‐K 3 YbSi 2 O 7 , space group Cmcm ) has been observed at about 210 K. β‐K 3 YbSi 2 O 7 is isostructural with K 3 ErSi 2 O 7 , whereas β′‐K 3 YbSi 2 O 7 adopts a new type of structure. Both compounds can be built up from a regular alternation of layers of two types, which are parallel to the (001) plane. In the octahedral layer, YbO 6 octahedra are isolated and linked by K1O 6+3 polyhedra. The second, slightly thicker sorosilicate layer is formed by a combination of Si 2 O 7 dimers and K2O 6+3 polyhedra. The boundary between the layers is a pseudo‐kagome oxide sheet based on 3.6.3.6 meshes. The phase transition is due to a tilt of the two SiO 4 tetrahedra forming a single dimer which induces a decrease of the Si—O—Si angle between bridging Si—O bonds from 180° (dictated by symmetry in space group P 6 3 / mmc ) to ≃164°. Magnetic characterization indicates that K 3 YbSi 2 O 7 remains paramagnetic down to 2 K, showing no apparent influence of the phase transformation on its magnetic properties. Analysis of the magnetization data revealed the positions of the three lowest crystal field levels of the Yb 3+ cations, as well as the corresponding projections of their angular momentum on the direction of the magnetic field.