On the Existence of PrSrO 3 -Type Phase and Its Bi/Pr-Substituted Solid Solution

ISSN： 0022-4596

Source： Journal of Solid State Chemistry, Vol.124, Iss.1, 1996-06, pp. : 176-181

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Abstract

Solid solution of the Pr 1.1(1- x ) Bi 0.8 x Sr 0.9+0.3 x O 2.932+0.094 x -type has been obtained and characterized through X-ray diffraction, effective valency of Bi and Pr, and through the density measurements. At 900#°C in air this solid solution begins from the Pr 1.1 Sr 0.9 O 2.932 -terminus and extends toward Bi 2 Sr 3 O 6 up to x [congruent with] 0.5 (20 at % Bi). Its crystal structure represents monoclinically distorted perovskite-type atomic arrangement, identical to that occurring in the Tb 1- x Bi x SrO 3 analog, several Tb-, and/or Pr-alkaline-earth binaries of the RE +4 Me O 3 -type ( Me = Sr or Ba), and to a large group of RE +3 Bi +5 Sr 2 O 6 -type ternaries. Characteristic features of this solid solution are ( i ) independent on x , constant oxidation states of Pr and Bi, equal to +3.694 and +4.565, respectively, resulting in x -dependent increase of the average effective valency of these components (V¯ ); (ii) x -dependent deficiency of the overall oxygen index, decreasing to 0 far above the solubility limit of Bi; and (iii) x -dependent deficiency of the cationic sublattice, increasing with the factor proportional to 0.2 x /(0.9 + 0.3 x ), i.e. to the atomic fraction of total Sr ions located on Pr sites.