Elsevier

Ceramics International

Volume 44, Issue 4, March 2018, Pages 3862-3867
Ceramics International

Physical properties of pseudo quaternary Na2B4O7 – SiO2 – MoO3 – Dy2O3 glasses

https://doi.org/10.1016/j.ceramint.2017.11.175Get rights and content

Abstract

Pseudo quaternary Na2B4O7–SiO2–MoO3–Dy2O3 glasses with various concentrations of Dy2O3 were synthesized and characterized by ultrasound, DTA and X-ray diffraction (XRD). It was found that, the density, the molar volume and the elastic moduli increased while the ultrasonic velocities and the packing density decreased with increasing of Dy2O3 concentration. The lower values of the radii and the bond length of B2O3, compared to those of Dy2O3, decreased the interatomic forces between the reactant glass forming cations and oxygens inside the glassy network. Accordingly, this will increase the molar volume and in the same time will decrease the average cross-link density, the ultrasonic velocities, the glass transition temperature and the thermal stability. Also, this may result in a high density glass sample which will increase the elastic moduli. Based on Lasocka's model, a good correlation between the temperature of both glass transition (Tgl) and crystallization peak (Tpc)was observed.

Introduction

Rare - earth (RE) doped glasses have become an important session of solids that attracting much attention among researchers [1], [2]. Now, a material doped with RE such as white light-emitting diodes (LEDs), motorized headlamp, backlighting, optical amplifiers, sensors, laser, and solar cells had a great development for solid-state lighting [3]. Alkali borosilicate glasses are environmentally friendly and are suitable host glasses with high transparency, high thermal stability, low melting point and good soluble for lanthanide ions [4], [5]. As a typical white light emission ion, different concentrations of trivalent dysprosium Dy+3 ion had drawn keen interest of research due to its potential application in magnetization which is built on the unidirectional light spread in optical isolator, that will give high Verdet constant [4].

Glasses based on transition metal oxides (TMO) like MoO3 have been the topic of intensive optical and electrical considerations due to their prospect applications in various domains of modern technology [6], [7]. The hopping of 3d1 unpaired electron from Mo3+ to Mo5+ sites in MoO3 based glasses controls the electrical conduction [8]. Moreover, MoO3–B2O3–SiO2 glasses are good RE ions solubility, optically transparent at the excitation and lasing wavelengths and had greater chemical resistance [9], [10], [11].

The numerous potential applications of glasses having a blend of RE and TMO prompted more examinations to explore their effects in the glass network and on the required applications [12], [13]. The precise choice of appropriate glass system for a particular application is controlled by several factors such as its mechanical properties. Several researches on the elastic moduli of RE borosilicate glasses containing TMO with the ultrasonic pulse-echo technique offer truthful information about their microstructure [14], [15], [16], [17].

The purpose of the current investigation is a systematic study of the influence of Dy2O3 on the ultrasonic parameters (ultrasonic velocities, bulk modulus (K) and Young's modulus (Y)) and the thermal stability of alkali borosilicate glasses containing MoO3.

Section snippets

Materials and methods

Five alkali borosilicate molybdate glasses modified with Dy2O3 were synthesized using melt-quenching technique and labeled as G1-G5 (Table 1). These materials were completely combined in an agate mortar. The melting procedure was performed in a platinum crucible at 1423 K for 1 h and poured on a brass plate. The glass samples were annealed at 673 K to minimize the internal mechanical stress and helped to obtain a glass sample with good mechanical stability. The two opposite faces of the prepared

Results and discussions

The synthesized glasses are fairly stable against devitrification and had low melting temperatures that saving energy and environmentally convenient.

Conclusions

Molybdenum alkali borosilicate glasses modified with various contents of Dy2O3 were synthesized. Dy2O3 has a heavier molar mass, higher values of radii, bond length and oxygen coordination number, than that of sodium diborate. Therefore, the increasing of Dy2O3 at the expense of Na2B4O7 created non-bridging oxygen atoms which opened up the network of the glasses and decrease the interatomic forces between the reactant glass forming cations and oxygens inside the glassy network. This may result

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