Structure, magnetic and positron lifetime studies on CaO–ZrO₂–SiO₂glass system doped with vanadium oxide

Abstract

The structure of CaO–ZrO2–SiO2 glasses doped with V2O5 (0.1–2 mole%) was studied using density and molar volume measurements. It was observed that the molar volume increased while the density decreased with increasing V2O5 content. Magnetic susceptibility measurements showed the diamagnetic behaviour of this glass system. The free volume was probed using ortho-positronium pick-off annihilation lifetime parameters. The mean free volume and fractional free volume have also been calculated from the positron annihilation lifetime data. The overall measured parameters from the structural and/or positron annihilation spectra indicated that the majority of the vanadium ions in the range 0–0.5 mole% of V2O5 are in the V5+ valence state which act as a glass former. On the other hand, the majority of the vanadium ions in the range 0.7–2 mole% of V2O5 are the V3+ and V4+ states acting as a glass modifier.

Electrical conductivity and positron annihilation characteristics of ternary silicone rubber/carbon black/TiB2 nanocomposites

“…Positron lifetime measurements were performed using a fastefast coincidence spectrometer (ORTIC) [10,11] with a resolution of~350 ps measured using a 60 Co source at room temperature.…”

Positron annihilation studies and complementary experimental characterization of xAg2O–(1 − x)(0.3CdO–0.7MoO3) metal oxide glass nanocomposites

“…Positron annihilation spectroscopy is a versatile non-destructive defect spectroscopic probe that has been increasingly applied in the investigation of the defects in nanomaterials and nanocomposites. [3][4][5] Positron lifetime (PL) measurements as well as coincidence Doppler broadening spectroscopy (CDBS) were performed on the seven samples and the results are discussed.…”

Analytical evidence for quantum states in aqueous vanadium pentoxide with positron lifetime spectroscopy

“…Besides of this, estimations of Ps lifetimes of some glasses doped with V 2 O 5 [8] shows that depending on the mole V 2 O 5 content, in vicinity of 1 mol %, lifetime slopes and remains constant at the increase of pentoxide fraction in the glass, positrons bond with non-bridging oxyden changing V 5+ ions onto paramagnetic V 4+ and V 3+ . So, the mechanism of the Ps ortho-para conversion may be considered to explain a positronium states.…”

“…Whereas the sol phase of vanadium pentoxide is puzzle in this meaning. There is a stimulated example of the hydration of V 2 O 5 powders in CaO-ZrO 2 -SiO 2 glasses, where lifetime positron annihilation data revealed changes in magnetic properties of the whole system caused by influence of V 5+ , V 4+ , and V 3+ paramagnetic ions [8] represented in the same mole fraction as that in aqueous sols.…”