Optical Investigation of Eu3+ Doped Bi12GeO20 (BGO) Crystals

M Kowalczyk,V.D Grigoryeva,T.F Ramazanova,B Fetliński,V.N Shlegel,M Malinowski,M Kaczkan

doi:10.3390/cryst10040285

Abstract

The spectroscopic properties of Eu3+ doped Bi12GeO20 (BGO) sillenite bulk crystals that were grown by the low-thermal-gradient Czochralski technique (LTG Cz) were investigated. The absorption spectra and the emission properties have been measured at room temperature (300 K) and at 10 K. Luminescence was observed both due to the direct Eu3+ ion excitation, as well as under UV excitation due to the energy transfer between Bi3+ and Eu3+ ions. Bi3+ → Eu3+ energy transfer mechanisms in Eu3+:BGO doped host were investigated. The Ωλ parameters, as well as radiative lifetimes, were calculated based upon the Judd-Ofelt formalism. The branching ratios and electric dipole transition probabilities were also determined, based upon the obtained experimental results. Luminescence has been observed from the 5D0,1,2 levels of Eu3+, with emissions from the 5D0 level being the strongest. The strongest observed luminescence band corresponds to the 5D0 → 7F0 transition at 578.7 nm. Reasons for the strong presence of the theoretically forbidden 5D0 → 7F0 emission were investigated.

Highlights

Bi12 GeO20 (BGO) crystal finds application in many photonic devices and systems [1,2,3,4,5,6]
The BGO crystal absorption spectrum taken in room temperature can be seen in
Absorption and emission spectra were recorded exists at room temperature and at 10 K

Summary

Introduction

Bi12 GeO20 (BGO) crystal finds application in many photonic devices and systems [1,2,3,4,5,6]. It is commonly found in Pockels cells and sensors due to its high electro-optic coefficient (3.3 pm/V) [1,2]. It is used in piezoelectric, Surface Acoustic Wave (SAW) devices [5]. BGO has a structure of the type of sillenite, which belongs to the space group I23 number 197 and possesses a cubic cell symmetry with lattice constant that is equal to 10.1455 Å and unit-cell volume of 1044.288244 Å3 , whereas the Bi-O bond lengths vary between 2.07 and 3.17 Å, as reported in the literature [1]

Results

Discussion

Conclusion