Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Structure and properties of orthoborate glasses in the Eu2O3-(Sr,Eu)O-B2O3 quaternary
Δημιουργός/Συγγραφέας:	Winterstein-Beckmann A. Möncke D. [EL] Παλλές, Δημήτρης[EN] Palles, Dimitris [EL] Καμίτσος, Ευστράτιος Ι.[EN] Kamitsos, Efstratios I. Wondraczek L.
Εκδότης:	American Chemical Society
Ημερομηνία:	2015
Γλώσσα:	Αγγλικά
ISSN:	1520-6106
DOI:	10.1021/jp5120465
Περίληψη:	The structure and properties of melt-quenched glasses and partially crystallized samples from the borate series (1-2x)Eu2O3-x((Eu,Sr)O-B2O3) were investigated in the supermodified regime of x < 0.5, using Raman, infrared (IR), electron spin resonance (ESR), and UV-vis absorption and fluorescence spectroscopic techniques. ESR and optical spectroscopy showed that, despite the strongly reducing synthesis conditions, the Eu2+/Eu3+ equilibrium remained shifted to the side of trivalent Eu3+. Stable and transparent overmodified borate glasses were produced for compositions with x ≤ 0.36. Higher europium oxide concentrations resulted in precipitation of crystalline Eu2Sr3(BO3)4 and EuBO3 phases, as traced by X-ray diffraction. Raman and IR spectroscopy showed that the metaborate configuration which is present at x = 0.46 transforms gradually, with increasing Eu2O3 levels, into orthoborate [BO3]3- triangular units. At higher europium oxide content (x ≤ 0.36), the presence of Eu3+ supports the formation of orthoborate [BØ2O2]3- tetrahedral species. These units organize into [B3O9]9- rings, which exist in equilibrium with [BO3]3- triangles. As a consequence, distinct variations can be observed also in the macroscopic properties such as density, glass transition temperature, refractive index, optical basicity, and oxygen polarizability. This observation confirms previous findings on manganese-strontium borates with high modification levels.
Τίτλος πηγής δημοσίευσης:	Journal of Physical Chemistry B
Τόμος/Κεφάλαιο:	119
Τεύχος:	7
Σελίδες:	3259-3272
Θεματική Κατηγορία:	[EL] Φυσική και θεωρητική χημεία[EN] Physical and theoretical chemistry [EL] Φασματοσκοπία[EN] Spectroscopy
Αξιολόγηση από ομότιμους (peer reviewed):	Ναι
Κάτοχος πνευματικών δικαιωμάτων:	© 2015 American Chemical Society.
Εμφανίζεται στις συλλογές:	Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο