Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bermanec, V. Articles by Kniewald, G. Search for Related Content GeoRef GeoRef Citation

Thermal stability and vibrational spectra of the sheet borate tuzlaite, NaCa[B₅O₈(OH)₂]·3H₂O

Vladimir Bermanec^1,*, Kreimir Furi², Maa Raji³ and Goran Kniewald⁴

¹ Mineralos ko petrografski zavod, Geolos ki odsjek, Prirodoslovno matematic ki fakultet, Horvatovac bb, HR-10000 Zagreb, Croatia
² Molecular Physics Laboratory, Rudjer Bos kovi Institute, POB 180, 10002 Zagreb, Croatia
³ Brodarski Institut, HR-10000 Zagreb, Croatia
⁴ Center for Marine and Environmental Research, Rudjer Bos kovi Institute, POB 180, 10002 Zagreb, Croatia

Correspondence: ^* E-mail: vberman{at}public.srce.hr

Tuzlaite, a hydrated pentaborate from the Tuzla evaporite deposit in Bosnia and Herzegovina, was analyzed for water content and loss upon heating using thermal analysis methods and vibrational spectroscopy. The resulting phases were identified by X-ray diffraction. The heating of tuzlaite results in a gradual loss of water over several dehydration steps. Two coordinated H₂O molecules escape at 191 °C. Between 248 and 298 °C two hydroxyl groups are eliminated, with an associated structural transformation. A continuous escape of the third water molecule occurs above 300 °C. A phase relationship model for different hydrated borate minerals implies the possible formation pathway of tuzlaite by sequential polymerization of the borate polyanion.