The present study focuses on critical factors limiting single-phase formation of Ba 2 Ti 9 O 20 (2 : 9). Apart from 2 : 9, other polytitanates that are richer in Ti or Ba could also be prepared as single-phase material without any stabilizing agent through chemical co-precipitation. 2 : 9 is found to be a stoichiometric compound and even 0⋅5% excess Ti or Ba leads to multiphase formation. Single-phase 2 : 9 could be achieved even through solid-state route without the addition of stabilizing

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... ts using high purity raw materials. The present results do not agree with existing hypotheses viz. diffusion, high surface and nucleation energy, potential barrier, nonstoichiometry etc as critical factors limiting formation of 2 : 9 as single-phase material.