Cation-deficient perovskite-related (Ba, La){sub n}Ti{sub n{minus}{delta}}O{sub 3n} (n {ge} 4{delta}) microphases in the La{sub 4}Ti{sub 3}O{sub 12}-BaTiO{sub 3} system: An HRTEM approach
- UMR-CNRS, Limoges (France). Sciences des Procedes Ceramiques et de Traitements de Surface
The large nonstoichiometric domain, observed in the La{sub 4}Ti{sub 3}O{sub 12}-rich part of the La{sub 4}Ti{sub 3}O{sub 12}-BaTiO{sub 3} system, has been shown to correspond to a continuous series of cation-deficient perovskite-related (Ba, La){sub n}Ti{sub n{minus}{delta}}O{sub 3n} (n {ge} 4{delta}) microphases. The crystal structures of these microphases have been analyzed by electron diffraction and high-resolution electron microscopy. They can be described as coherent intergrowths of P-perovskite-like blocks La{sub 4}Ti{sub 3}O{sub 12} and Q-perovskite-like blocks BaLa{sub 4}Ti{sub 4}O{sub 15}, respectively, constitutive of the simple basic terms n = 4 and n = 5 of the previously identified (Ba, La){sub n}Ti{sub n{minus}1}O{sub 3n} series. The corresponding Ba{sub Q}La{sub 4(P+Q)}Ti{sub 3P+4Q}O{sub 12P+15Q} microphases can thus be denoted by 4{sup P}5{sup Q} in a compact form. In fact, only the 4{sup P}5{sup 1} intergrowth sequences have been observed. Eight of these are clearly shown by direct imaging. No intergrowth terms were observed for compositions ranging from BaLa{sub 4}Ti{sub 4}O{sub 15} (n = 5) to Ba{sub 2}La{sub 4}Ti{sub 5}O{sub 18} (n = 6). The ability of the system to develop coherent intergrowths has been discussed in the light of information provided by an accurate analysis of crystal structures of the basic members of the series: La{sub 4}Ti{sub 3}O{sub 12} (n = 4), BaLa{sub 4}Ti{sub 4}O{sub 15} (n = 5), and Ba{sub 2}La{sub 4}Ti{sub 5}O{sub 18} (n = 6).
- OSTI ID:
- 679249
- Journal Information:
- Journal of Solid State Chemistry, Vol. 145, Issue 2; Other Information: PBD: Jul 1999
- Country of Publication:
- United States
- Language:
- English
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