Skip to Main Content
GEOREF RECORD

IR spectroscopy of hemimorphite between 82 and 373 K and optical evidence for a low-temperature phase transition

Eugen Libowitzky and George R. Rossman
IR spectroscopy of hemimorphite between 82 and 373 K and optical evidence for a low-temperature phase transition
European Journal of Mineralogy (August 1997) 9 (4): 793-802

Abstract

Polarized IR absorption spectra of oriented hemimorphite single crystals were recorded in the region of the O-H fundamentals and combination bands between 82 and 373 K. The weak H bonds of the OH groups and water molecules are confirmed by the energies of the OH stretching fundamentals around 3350-3600 cm (super -1) . Two O-H stretching bands in both a and c are predicted by factor group analysis, but the bands observed are three strong bands in a and two in c: these results indicate complicated dynamics of the water molecule and OH groups within the structural channels. Although these motions can be explained by a twisting motion of the water molecule around its two-fold molecular axis, it is considered that a much better interpretation can be found in dynamic proton disorder, which describes a hopping motion between disordered proton sites. A possible dynamic disorder-order phase transition at low T was tested by determination of the birefringence values (Delta n) of hemimorphite between 82 and 373 K; a strong discontinuity in the slope of Delta n (sub XY) and Delta n (sub YZ) was noted at 98 K which, together with considerable energy shifts of IR bands on cooling, provides evidence for a low-T second-order phase transition in hemimorphite.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 9
Serial Issue: 4
Title: IR spectroscopy of hemimorphite between 82 and 373 K and optical evidence for a low-temperature phase transition
Affiliation: Universitaet Wien-Geozentrum, Institut fuer Mineralogie und Kristallographie, Vienna, Austria
Pages: 793-802
Published: 199708
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 33
Accession Number: 1997-070804
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: 1 table
Secondary Affiliation: California Institute of Technology, Pasadena, CA, USA, United States
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199723
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal