RE)/2
) is constant and equal to ϩ4, as in binary counter-Solid solution of the Pr 1.1(1؊x) Bi 0.8x Sr 0.9؉0.3x O 2.932؉0.094x -type has parts.
been obtained and characterized through X-ray diffraction,
The compositional interval between these two groups effective valency of Bi and Pr, and through the density measureof isostructural materials has not been studied yet, apart ments. At 900؇C in air this solid solution begins from the from our recent effort (10) centered on the extension of Pr 1.1 Sr 0.9 O 2.932 -terminus and extends toward Bi 2 Sr 3 O 6 up to x Х TbSrO 3 into the ternary system with bismuth oxide. Thanks 0.5 (20 at % Bi). Its crystal structure represents monoclinically to this, a terminal solid solution of the Tb 1Ϫx Bi x SrO 3 -type distorted perovskite-type atomic arrangement, identical to that (x ϭ ) has been described in which effective valency of occurring in the Tb 1؊x Bi x SrO 3 analog, several Tb-, and/or Prthe average Me ions (Me ϭ Tb 1Ϫx Bi x ) occurs to be constant alkaline-earth binaries of the RE ؉4 MeO 3 -type (Me ؍ Sr or Ba), indeed and equal to ϩ4. and to a large group of RE ؉3 Bi ؉5 Sr 2 O 6 -type ternaries. Charac-In this light, investigation of the Bi-Pr-Sr-O system, at teristic features of this solid solution are (i) independent on x, least of that part which is situated in close vicinity of constant oxidation states of Pr and Bi, equal to ؉3.694 and ؉4.565, respectively, resulting in x-dependent increase of the PrSrO 3 , may represent certain scientific interest, namely average effective valency of these components (V ¯); (ii)
x-depena unique opportunity to stabilize the ϩ4 oxidation state dent deficiency of the overall oxygen index, decreasing to 0 far of Pr and to determine its possible variation vs content of above the solubility limit of Bi; and (iii) x-dependent deficiency bismuth. This is especially important if we consider that of the cationic sublattice, increasing with the factor proporof the binary Pr-alkaline-earth phases of PrMeO 3 -type, tional to 0.2x /(0.9 ؉ 0.3x), i.e. to the atomic fraction of total only PrBaO 3 has been reported in the literature up to now.
Sr ions located on Pr sites.