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The Crystallization of Ba‐Substituted CsTiSi 2 O 6.5 Pollucite Using CsTiSi 2 O 6.5 Seed Crystals
Author(s) -
Garino Terry J.,
Nenoff Tina M.,
Park TaeJin,
Navrotsky Alexandra
Publication year - 2009
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.1551-2916.2009.03164.x
Subject(s) - crystallization , barium , materials science , phase (matter) , crystallography , nucleation , x ray crystallography , amorphous solid , crystal structure , mineralogy , analytical chemistry (journal) , chemistry , diffraction , metallurgy , organic chemistry , physics , optics
Barium (Ba)‐substituted CsTiSi 2 O 6.5 materials of two types, Cs x Ba 1− x TiSi 2 O (7− x /2) and Cs x Ba (1− x )/2 TiSi 2 O 6.5 were synthesized with the pollucite structure with 1≥ x ≥0.6. When the Ba‐substituted precursor materials were heat treated to 850°C for 4 h, a mixture of amorphous and unidentifiable phases formed. However, with the addition of 10 wt% of crystalline CsTiSi 2 O 6.5 to the Ba‐containing precursors, nearly single‐phase pollucite was obtained after 20 h at 750°C for x ≥0.6. The added crystalline CsTiSi 2 O 6.5 particles act as nuclei that allow the Ba‐containing materials to crystallize into the pollucite phase and to avoid the formation of unwanted phases that would otherwise nucleate and grow. These new materials can be used to study the stability of CsTiSi 2 O 6.5 as a durable ceramic waste form, which could accommodate with time both Cs and its decay product, Ba.