Authors Friedel, P. ; Bergmann, J. ; Kleeberg, R. ; Schubert, G.
Title A proposition for the structure of ammonium hydrogen (acid) urate from uroliths
Date 01.01.2006
Number 12583
Abstract From naturally formed ammonium hydrogen urate, a common compound in uroliths, X-ray powder diffraction measurements, indexing and force-field-constrained Rietveld refinement including anisotropic characterization of peak width broadening were performed using the BGMN[tm] program. The ammonium hydrogen (acid) urate crystallizes in a triclinic unit cell with a = 0:3650 (3), b = 1:0215 (4), c = 1:0597 (5) nm, a = 113:9 (1), ß = 91:1(1) and · = 92:3(1)°. The symmetry was determined as P 1 (Space group No. 2). The agreement factor Rwp could be obtained to 7:43%. Inside the unit cell an additional ammonia molecule was placed with a probability of pNH3 = 0:34. This reduced occupancy and the anisotropic peak width hint to structural gradient related to the varying conditions of formation.
Publisher Zeitschrift für Kristallographie
Citation Zeitschrift für Kristallographie 23 (2006) 517-522

Back to list