Herstellung und Reaktion von Gliedern der Hollandit-Gruppe MxMn8O16 (M = K, Rb, Cs, Ca, Sr, Pb; x = 1 und M = Na; x = 1.9)
Hollandite, cryptomelane, manjiroite, and coronadite were synthesized by hydrothermal methods at 500 °C and 2 kbar in order to determine their unit cell dimensions and analytical composition from fully crystalline samples. Analyses, X-ray diffraction, and electron microscopy have shown that the tun...
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| Main Authors: | , |
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| Format: | Article |
| Language: | deu |
| Published: |
Swiss Chemical Society
1989-03-01
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| Series: | CHIMIA |
| Online Access: | https://www.chimia.ch/chimia/article/view/9890 |
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| Summary: | Hollandite, cryptomelane, manjiroite, and coronadite were synthesized by hydrothermal methods at 500 °C and 2 kbar in order to determine their unit cell dimensions and analytical composition from fully crystalline samples. Analyses, X-ray diffraction, and electron microscopy have shown that the tunnel structure accommodates 1 K, Rb, Cs, Ca, Sr, or Pb but ca. 2 Na per unit Mn8O16. Crystalline samples show no conceivable ion exchange nor are they attacked by concentrated nitric acid at room temperature. Finely divided cryptomelane, however, is attacked by conc. HNO3. The unit cell dimensions as well as the relations between ionic radius of the tunnel ion, symmetry, and composition are discussed.
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| ISSN: | 0009-4293 2673-2424 |