The crystal structures of NaMgPO 4 , Na 2 CaMg(PO 4 ) 2 and Na 18 Ca 13 Mg 5 (PO 4 ) 18 : new examples for glaserite related structures

✍ Scribed by Alkemper, J.; Fuess, H.

• Book ID: 120652853
• Publisher: Oldenbourg Wissenschaftsverlag
• Year: 1998
• Tongue: English
• Weight: 797 KB
• Volume: 213
• Category: Article
• ISSN: 2194-4946
• DOI: 10.1524/zkri.1998.213.5.282

✦ Synopsis

Abstract

Three phosphates with (NaM^II^PO~4~)~x~ composition have been synthesized and characterized structurally. The low temperature modifications of NaMgPO~4~ and Na~2~CaMg(PO~4~)~2~ crystallize in the orthorhombic space group __P__2~1~2~1~2~1~, and the monoclinic space group __P__2~1~/c, respectively. The phase transitions at high temperature were investigated by thermal analysis and powder diffractometry. The high-temperature modification of Na~2~CaMg(PO~4~)~2~ is isotypic with glaserite, K~3~Na(SO~4~)~2~ as determined by Rietveld refinement. Na~18~Ca~13~Mg~5~(PO~4~)~18~ crystallizes in the trigonal space group R[unk]m. The structures of all of these phosphates can be related to the arrangement of cations and phosphate tetrahedra in the glaserite structure.