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Polymorphism of Ba 2 SiP 4
Author(s) -
Haffner Arthur,
Weippert Valentin,
Johrendt Dirk
Publication year - 2020
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201900188
Subject(s) - crystallography , polymorphism (computer science) , materials science , raman spectroscopy , phase (matter) , chemistry , physics , biochemistry , organic chemistry , genotype , gene , optics
The three‐dimensional SiP 4 network in the known phosphidosilicate Ba 2 SiP 4 ‐ tI 28 is analogous to β‐Cristobalite if oxygen is formally replaced by P–P dimers. Here we report a second polymorph Ba 2 SiP 4 ‐ oP 56 [ Pnma, a = 12.3710(4) Å, b = 14.6296(7) Å, c = 7.9783(3) Å; Z = 8] with chains of SiP 4 tetrahedra connected by P–P bonds, reminiscent to the elusive fibrous SiO 2 . Ba 2 SiP 4 is enantiotropic. The high temperature polymorph Ba 2 SiP 4 ‐ oP 56 transforms to the low‐temperature phase Ba 2 SiP 4 ‐ tI 28 at 650 °C and reconstructs to the high‐temperature modification at 1100 °C. DFT calculations predict an indirect optical bandgap of about 1.7 eV.