Ultrasonic study on complex glass system doped with erbium oxide
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Mohamed A. Farag, Khaled Abd-ullah Abd El-Rahman, and Mohamed M. El-Okr Physics Department, Faculty of Science, El-Azhar University, Cairo, Egypt (Received 25 August 2015; accepted 14 January 2016)
Glasses doped with rare earth elements (lanthanide series) are the most popular materials used in upconversion devices. The main aspect to develop these devices is to find suitable host materials for rare earth ions. The host material should have a high transmission of the upconverted photons, high thermal stability, good mechanical properties, low price, and easy to manufacture and shaping. Present work is concerned with studying the mechanical and structural properties for the oxide glass system doped with rare earth metal (erbium oxide, Er2O3). Ultrasonic pulse-echo technique is used to measure the sound velocities in the glass system (30%B2O330%Bi2O320% Li2O10%BaO10%Pb3O4xEr2O3), (x 5 0, 0.5, 1, 2, 3, 4) mol%. Ultrasound velocities (longitudinal and shear) are measured as a function of the Er2O3 content at a frequency of 4 MHz for longitudinal wave and 2 MHz for the shear wave at a temperature of 300 K. The elastic moduli and some physical parameters, such as Debye temperature, coordination number, and compressibility, were evaluated. Furthermore, the dimensionality of the glass network has been calculated in terms of the d ratio which equals G/B ratio. These parameters beside the x-ray diffraction, differential scanning calorimetry, and Fourier Transform Infrared (FTIR) measurements throw more light on the structure of the glass system. The measurements in this study exhibit remarkable anomalous changes in the network structure of the investigated glass doped with Er2O3. I. INTRODUCTION
Rare earth, as active ions, doped materials have been investigated as upconversion media for several years, but it is still holding a great challenging to find a suitable host material to be applied onto the photovoltaic (PV) device. Glass materials are preferred as a host material due to their stability and the capability of easy shaping for these PV devices into slips, lenses, and all other optical shapes. Upconversion is difficult to generate in conventional oxide glasses due to their high phonon energies, corresponding to the stretching vibrations of the oxide glass’s network former. However, oxide glasses have attractive properties, such as high chemical stability and ease of fabrication. Many oxide glasses have been studied intensively to find the suitable upconversion host material. The prepared glass with the molar composition (mol%) 30B2O3–30Bi2O3–20Li2O–10BaO–10Pb3O4 (B30Bi30Li20Ba10Pb10) is considered a stable glass with a wide range of transparency (450–2500 nm), high density (6.3 g/cm3). The long infrared cutoff edge indicated that the phonon energy of (B30Bi30Li20Ba10Pb10) glass is small compared to other conventional oxide glasses.
Contributing Editor: Himanshu Jain a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.27
This work is concerned with studying the phys
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