Redetermination of the crystal structure of , and its thermal behaviour in the range

✍ Scribed by Lars Peters; John S.O. Evans

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 435 KB
• Volume: 180
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2007.06.009

✦ Synopsis

The crystal structure of aÀGeðHPO 4 Þ 2 Á H 2 O ðaÀGePÞ was redetermined using X-ray powder diffraction methods. Reindexing the pattern showed that the monoclinic angle is b ¼ 108:985ð1Þ and the lattice parameters a ¼ 8:2920ð2Þ Å, b ¼ 4:7880ð1Þ Å, c ¼ 16:4058ð3Þ Å, rather than the reported b ¼ 110:2ð4Þ , a ¼ 8:230ð2Þ Å, b ¼ 4:784ð1Þ Å, c ¼ 16:502ð5Þ Å in space group P2 1 =c. This apparently minor change in the cell parameters is important as it otherwise leads to incorrect Ge-O and P-O distances. Variable temperature X-ray diffraction experiments give an insight into the thermal behaviour of aÀGeP in the temperature range from 300 to 16 K. aÀGeP behaves as expected for a layered structure, showing a much larger expansion perpendicular to the layers than within the layers. The monoclinic angle increases with decreasing temperature. No temperature induced phase transitions have been observed in the temperature interval studied.