Compositional evolution of the NaZn13 structure motif in the systems La–Ni–Ga and Ce–Ni–Ga
Autor: | Mauro Coduri, Leonid Vasylechko, Wilder Carrillo-Cabrera, Yurii Prots, Christina Drathen, Ulrich Burkhardt, Yuri Grin, Dariusz Kaczorowski |
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Rok vydání: | 2018 |
Předmět: |
Phase transition
Materials science 010402 general chemistry 010403 inorganic & nuclear chemistry 01 natural sciences 0104 chemical sciences Inorganic Chemistry Pearson symbol Crystallography Paramagnetism Tetragonal crystal system Electron diffraction Orthorhombic crystal system Crystal twinning Powder diffraction |
Zdroj: | Dalton Transactions. 47:12951-12963 |
ISSN: | 1477-9234 1477-9226 |
Popis: | Phase relationship and structural behaviour in the substitutional series LaNi13-xGax and CeNi13-xGax have been studied by a combination of X-ray powder diffraction measurements, differential scanning calorimetry, electron diffraction tomography and metallographic analyses. The sequence of morphotropic phase transformations has been found in the series LaNi13-xGax resulting in five varieties of the NaZn13 structure: the cubic phase with aristotype structure at x = 2 (space group Fm3[combining macron]c, Pearson symbol cF112), two tetragonal phases at x = 2.5-4.25 (space group I4/mcm, Pearson symbol tI56-I) and 7-7.5 (space group I4/mcm, Pearson symbol tI56-II), both with an atomic arrangement of the CeNi8.5Si4.5 type and two orthorhombic phases at x = 4.5-5.75 (LaNi7In6 structure type, space group Ibam, Pearson symbol oI56) and x = 6.37-6.87 (a new derivative of the NaZn13, prototype structure, space group Fmmm, Pearson symbol oF112). The related series CeNi13-xGax shows similar behaviour. The corresponding tI56-I ↔oI56 ↔oF112 ↔tI56-II phases are formed at x = 4-4.25, 4.5-6, 6.37-6.87 and 7-7.37, respectively. In contrast to the lanthanum analogues, the phase with cubic symmetry was not found for this system. Complex twinned and multiple twinned (twinning of twins) domain structures which are revealed for the tetragonal and both orthorhombic phases clearly indicate temperature-induced polymorphic phase transitions during the formation of these phases. LaNi13-xGax samples show paramagnetic behavior, whereas the CeNi13-xGax series exhibits Curie-Weiss paramagnetism. |
Databáze: | OpenAIRE |
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