Structure study of MoO 3–ZnO–B 2O 3 glasses by Raman spectroscopy and formation of α-ZnMoO 4 nanocrystals

Abstract

Molybdenum oxide (MoO 3)-containing glasses of xMoO 3–50ZnO–(50− x)B 2O 3 ( x = 10, 20, and 30) are prepared using a conventional melt quenching method, and the glass structure and crystallization behaviour are clarified. It is found that the thermal stability against crystallization of the glasses decreases drastically with increasing MoO 3 content. The main valence of Mo ions in the glasses is found to be Mo 6+ from X-ray photoelectron spectroscopy measurements. The Raman bands observed at ∼860 cm −1 and 950 cm −1 suggest that the coordination state of Mo 6+ ions in the glasses is mainly (MoO 4) 2− tetrahedral units. All glasses examined in this study give the formation of α-ZnMoO 4 as the initial crystalline phase. In particular, 30MoO 3–50ZnO–20B 2O 3 glass shows the bulk crystallization of α-ZnMoO 4 nanocrystals with a diameter of ∼5 nm. The crystallized glasses consisting of Eu 3+-doped ZnMoO 4 crystals are synthesized, and enhanced photoluminescence emissions (i.e., the quantum yield is 9%) due to the 4 f transitions 5D 0 → 7F J ( J = 0–4) of Eu 3+ ions is observed.