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Stabilization of Ordered Zirconium Titanates through the Chemical Substitution of Ti 4+ by Al 3+ /Ta 5+
Author(s) -
Zhang Yan,
Davies Peter K.
Publication year - 1994
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1994.tb05359.x
Subject(s) - zirconium , isostructural , solid solution , materials science , crystallography , crystal structure , annealing (glass) , inorganic chemistry , chemistry , metallurgy
We have investigated the ZrO 2 –AITaO 4 system to understand how selected chemical substitutions can be used to control cation‐ordering transformations in zirconium titanate based dielectric ceramics. The complete replacement of the Ti content of Zr x Ti 2–x O 4 by a coupled Al 3+ /Ta 5+ substitution permits the synthesis of a wide range of isostructural Zr x (Al 0.5 Ta 0.5 ) 2–x O 4 solid solutions. At high temperatures a disordered α‐PbO 2 type of structure is formed for 0.375 ≤ x ≤ 1.03. Samples with 0.67 ≤ x ≤ 1.03 undergo a cation‐ordering reaction to a structure in which the a and b axes of the parent disordered Cell are doubled. The stabilities of these cation‐ordered derivative structures are significantly greater than those of the ordered zirconium titanates. The ordering temperatures are composition dependent with a maximum of 1393°C occurring for Zr 0.86 (Al 0.5 TaO 0.5 ) 1.14 O 4 . The higher transition temperatures also enhance the kinetics of the ordering transition; whereas the pure zirconium titanates require extended annealing to produce complete cation order, fully ordered Zr χ (Al 0.5 Ta 0.5 ) 2–χ O 4 solid solutions are produced during a normal furnace cool.