The local structure of gadolinium vanadate–tellurate glasses and glass ceramics: Te2V2O9 crystalline phase

Abstract

Glasses in the system xGd 2 O 3 Á (100 -x) [0.7TeO 2 Á 0.3V 2 O 5 ] with 0 B x B20 mol% have been prepared from melt quenching method. Influence of gadolinium ions on structural behavior in vanadate-tellurate glasses has been investigated using FTIR spectroscopy, X-ray diffraction (XRD), and magnetic susceptibility measurements. The structural changes have been analyzed with increasing rare earth concentration. The structural changes, as recognized by analyzing band shapes of XRD and FTIR spectra, revealed that Gd 2 O 3 causes a higher extent of network polymerization as far as 20 mol%. The structure of the heat-treated glasses was found to consist mainly of the Te 2 V 2 O 9 crystalline phase. These vitreous systems were investigated by magnetic susceptibility measurements. From the paramagnetic susceptibility v was calculated at different temperature and from the 1/v(T) graph, the Curie temperature of the glass has been evaluated. Magnetic susceptibility data show the presence of small antiferromagnetic interactions between the Gd ?3 ions.

Competitive role of the tellurium and gadolinium cations in structural aspects of the gadolinium–phosphate–tellurate glasses

“…Since the stretching force constant of Te-O bonding is substantially lower than that of the P-O, the stretching frequency of Te-O-P might trend to be lower. Such a behavior, namely the increase of the polymerization degree of the structural units with increasing the rare earth ion content by heat treatment was previously reported based on IR spectroscopy data for other glasses [38][39][40][41][42][43][44][45][46][47][48][49][50][51].…”

Absolute calibration of low- and high-field magnetic susceptibilities using rare earth oxides

“…They determined an extrapolated Curie temperature of −18 K and we also did so. Such a negative paramagnetic Curie temperature implies that there are small anitiferromagnetic interactions between some clustered Gd 3+ ions [e.g., Mele et al, 2009;Rada et al, 2009]. A same correction of sign was made also for dysprosium oxide in the database III/ 12c, suggesting that such errors are inevitable in this kind of database.…”