Synthesis and spectroscopic characterization of apjohnite and pickingerite
Raman spectroscopy complimented with infrared ATR spectroscopy has been used to characterise two synthetic halotrichites: apjohnite MnSO4.Al2(SO4)3.22H2O and pickingerite MgSO4.Al2(SO4)3.22H2O. A comparison is made with the spectra of natural pseudo-alums halotrichite, pickingerite and apjohnite. Two Raman bands observed at 995 and 990 cm-1 for apjohnite and a single band at 984 cm-1 for pickingerite are assigned to the ￮1(Ag) SO4 symmetric stretching vibrations. Raman bands observed at 1141 and 1080 cm-1 for apjohnite and 1096 and 1058 cm-1 for pickingerite are assigned to the antisymmetric stretching vibration ￮3(Bg) SO4. Raman bands at 474, 460 and 423 cm-1 for apjohnite and at 459 and 445 cm-1 for pickingerite are attributed to the ￮2(Ag) SO4 mode. The band at 618 cm-1 is assigned to the ￮4(Bg) SO4 mode. The splitting of the ￮2, ￮3 and ￮4 modes is attributed to the reduction of symmetry of the SO4 and it is proposed that the sulphate coordinates to water in the hydrated aluminium in bidentate chelation.
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|Item Type:||Journal Article|
|Additional Information:||This paper is one of a series of manuscripts on sulphate secondary minerals formed from aqueous solutions such as with acid mine drainage.|
|Keywords:||apjohnite, pickingerite, sulphate, halotrichite, jarosite, infrared and Raman spectroscopy|
|Subjects:||Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > INORGANIC CHEMISTRY (030200)|
|Divisions:||Past > QUT Faculties & Divisions > Faculty of Science and Technology|
|Copyright Owner:||Copyright 2006 Elsevier|
|Copyright Statement:||Reproduced in accordance with the copyright policy of the publisher.|
|Deposited On:||20 Nov 2006|
|Last Modified:||05 May 2014 23:44|
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