ISSN:
1600-5767
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Geosciences
,
Physics
Notes:
Large crystals of the new orthophosphate K2MgWO2(PO4)2 [dipotassium magnesium tungsten dioxide bis(monophosphate), `KMgWP'] were grown from a stoichiometric melt at about 1068 K. They were found to crystallize tetragonally in point symmetry group 422. On cooling to room temperature, they undergo at least three reversible, ferroic, solid-state phase transitions. Two additional anomalies were found within the stability field of KMgWP's tetragonal high-temperature phase (HT KMgWP), which is stable above T = 537 K. Its structure was solved and refined in space group P41212 at T = 773 K from X-ray powder diffraction data by the Rietveld method (Rwp = 3.59%, RBragg = 3.39%) using the program WYRIET3. A brief structural comparison of HT KMgWP with its triclinic pseudo-tetragonal room-temperature modification reveals that the potassium ions, occupying interstices within the rigid network of [MgWO2(PO4)2]2−, are affected most by the phase transitions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0021889897006389
Permalink