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The n=2 Member of the New Layered Structural Family Ba5+nCa2Mn3+nO3n+14 Derived from the Hexagonal Perovskite: Ba7Ca2Mn5O20

✍ Scribed by N. Floros; C. Michel; M. Hervieu; B. Raveau

Publisher
Elsevier Science
Year
2002
Tongue
English
Weight
426 KB
Volume
168
Category
Article
ISSN
0022-4596

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✦ Synopsis

A new manganese oxide Ba 7 Ca 2 Mn 5 O 20 , with an original structure derived from the 21 L hexagonal perovskite, has been synthesized and studied by XRPD and HREM. This rhombohedral phase (R % 3m), with a ¼ 5:8207ð2Þ ( A and c ¼ 51:359ð1Þ ( A, consists of [BaO 3 ] (h and c) layers and [BaO 2 ] (c 0 ) layers with a ðhhccc 0 ccÞ 3 stacking sequence. This structure is closely related to that of Ba 8 Ca 1.8 Mn 6.2 O 23Àd , containing identical blocks ''Ba 5 Ca 2 Mn 3 O 14 '' built up of layers of corner-sharing CaO 6 octahedra, MnO 6 octahedra and MnO 4 tetrahedra. Both oxides can be described as the members n ¼ 2 and 3 of the new structural family Ba 5+n Ca 2 Mn 3+n O 3n+14 , which differs from the hexagonal perovskite family by its bidimensional character, due to the disconnection of the MnO 4 tetrahedra layers. The charge distribution of manganese, Mn 3+ /Mn 4+ in octahedra and Mn 5+ in tetrahedra is a particular feature of this structure. # 2002 Elsevier Science (USA)

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The Oxycarbonate Y1.6Ca0.4Ba4Cu5CO3O11,
The Oxycarbonate Y1.6Ca0.4Ba4Cu5CO3O11, n = 2 Member of the "123"-Type Derivatives (Y1-xCax)nBa2nCu3n-1CO3O7n-3
✍ M. Hervieu; Ph. Boullay; B. Domengès; A. Maignan; B. Raveau 📂 Article 📅 1993 🏛 Elsevier Science 🌐 English ⚖ 394 KB

The exploration of the system \(\mathrm{Y}-\mathrm{Ba}-\mathrm{Cu}-\mathrm{C}-\mathrm{O}\), using high resolution electron microscopy, has allowed the oxycarbonate \(\mathrm{Y}_{1.6} \mathrm{Ca}_{0.4} \mathrm{Ba}_{4} \mathrm{Cu}_{5} \mathrm{O}_{11} \mathrm{CO}_{3}\) to be isolated. This 123 derivati