Synthesis and structural studies of Sr2Co2−xGaxO5, 0.3⩽x⩽0.8

Synthesis and structural studies of Sr2Co2−xAlxO5, 0.3⩽x⩽0.5

“…However, reannealing of the prepared compounds at lower temperatures down to 1050 C did not influence the variation of FWHM with 2Y: Decreasing the temperature to 950 C led to decomposition of Sr 2 Co 2Àx Al x O 5 . This is not surprising, since both Sr 2 Co 2 O 5 [15] and Sr 2 Co 2Àx Ga x O 5 [13] …”

“…This image also reveals another type of domain within the thinnest part of the crystal, sharing the same perovskite sub-axis, marked as b and oriented along the [010] BM zone axis, as can be seen in the corresponding FFT. Computed simulated images are inserted in the right part of the image for clarity, using the coordinates for the brownmillerite type compound Sr 2 Co 1.3 Ga 0.7 O 5 [13]. Fig.…”

“…Recently we have successfully stabilized the brownmillerite structure for Sr 2 Co 2 O 5 by replacing Co 3+ by Ga 3+ : Sr 2 Co 2Àx Ga x O 5 , 0:3pxp0:8 [13]. Here we present the preparation and electron microscopy studies of new complex cobalt oxides with composition Sr 2 Co 2Àx Al x O 5 .…”

Ferromagnetism in a New Manganese‐Related Brownmillerite: La0.5Sr0.5MnO2.5

“…We should point out at this point that brownmillerite compounds generally crystallise in either the Ibm2 [32] or Pnma [33] space group. However, there are also a few papers [33][34][35][36] that report a better fit of the Rietveld refinement using the Icmm space group as a consequence of order/disorder phenomena. In fact, SAED studies with Ba 2 In 2 O 5 [35] and Sr 2 Co 2Àx Ga x O 5 [36] have revealed the appearance of diffuse streaking along certain directions, which confirms the presence of order/disorder phenomena.…”

“…However, there are also a few papers [33][34][35][36] that report a better fit of the Rietveld refinement using the Icmm space group as a consequence of order/disorder phenomena. In fact, SAED studies with Ba 2 In 2 O 5 [35] and Sr 2 Co 2Àx Ga x O 5 [36] have revealed the appearance of diffuse streaking along certain directions, which confirms the presence of order/disorder phenomena. In the Icmm space group, the 8i sites corresponding to the metal lying at the tetrahedral position and one of the oxygen atoms [O(3)] have mean occupancies of one half, which allows disordered displacements of these atoms.…”