caa a22 4500 378890093 CHVBK 20180305123452.0 cr unu---uuuuu 161128e20040601xx s 000 0 eng 10.1524/zkri.219.6.359.34644 doi (NATIONALLICENCE)gruyter-10.1524/zkri.219.6.359.34644 Stöwe Klaus Polymorphic forms of Rb2Te: in-situ high-pressure DAC X-ray diffraction investigations and structure modelling with CASTEP [Elektronische Daten] [Klaus Stöwe] We report on high pressure X-ray diffraction investigations of Rb2Te in diamond anvil cells DAC (Mo Kα1 radiation, Rietveld refinement of the diffraction diagrams), which resulted in a polymorphic transformation series for the compound Rb2Te from an anti-fluorite type into an anti-cotunnite type (transition pressure 0.5 GPa) and further on into a Ni2In type structure (transition pressure 1.5 GPa). Among the compounds of the composition A2B Rb2Te has up to now an exceptional position in so far, as this sequence of polymorphic forms is also observed as a high-temperature transformation series. Geometry optimizations on the basis of DFT calculations with the program CASTEP confirmed the phase transitions observed experimentally. Since the anti-cotunnite and the Ni2In type are structurally related — between both structure types there is a group-subgroup relation with the Ni2In type as aristo-type (1st Landau criterion) — the transition between the two types can be characterized as continuous in real space coordinates. According to experimental data as well as results of the CASTEP calculations the phase transition takes place with a discontinuity in the volume versus pressure curve. The geometry optimizations give direct insight in the continuous mechanism of the transition and offer the possibility to compare intermediate structural arrangements with other structures to be discussed in this context, as e.g. the post-cotunnite or the Co2Si structure-type. © 2004 Oldenbourg Wissenschaftsverlag GmbH Crystallography nationallicence Inorganic chemistry nationallicence Organic chemistry nationallicence Zeitschrift für Kristallographie - Crystalline Materials De Gruyter Oldenbourg 219/6(2004-06-01), 359-369 2194-4946 219:6<359 2004 219 zkri https://doi.org/10.1524/zkri.219.6.359.34644 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1524/zkri.219.6.359.34644 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Stöwe Klaus NATIONALLICENCE 773 0- Zeitschrift für Kristallographie - Crystalline Materials De Gruyter Oldenbourg 219/6(2004-06-01), 359-369 2194-4946 219:6<359 2004 219 zkri CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter