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2The 30th International Conference on Advanced Laser Technologies
ALT'23
LS-O-13
Influence of doping with lanthanides (Eu-Yb) on optical properties of
samarium-scandium borate crystals
A.Y. Jamous1'2, V.A. Svetlichnyi1, A.B. Kuznetsov2, A.E. Kokh2
1- Tomsk State University, Tomsk 634050, Russia 2- Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk 630090, Russia
Email: ammarjamous2@gmail.com
Presently, borates, particularly rare-earth borates, are intensively investigated as potential functional materials for scintillators, phosphors, and nonlinear optical converters. This attention is due to their ease of preparation: chemical stability, short UV absorption edge, good optical and laser characteristics, as well as diversity of crystal structures. Owing to 5d-4f or 4f-4f transitions in several rare earth elements, it is possible to obtain light emission in different spectral regions. Especially, compounds containing Sm3+ are of interest for preparing red phosphors. Recently, we reported the optical properties of new two-cationic SmxSc4-x(BO3)4 (SSB) solid solutions basing on the SmSc3(BO3)4 compound [1]. In this work, lanthanides-doped samarium-scandium borates (RE:SSB) are presented. The effect of doping with various lanthanides both on the spectral properties of Sm3+, and on the efficiency of second harmonic generation (SHG) is determined. Crystals with general formula RExSmyScz(BO3)4 (x+y+z = 4, RE = Eu-Yb) were grown by TSSG method. XRD analyze showed that they are nonlinear biaxial monoclinic crystals. The absorption and photoluminescence (PL) were investigated in IR-Vis-UV regions. Additionally, the SHG of Nd:YAG laser radiation (1064 nm, 7 ns) was studied using the Kurtz-Perry powder technique [2].
All absorption bands that are corresponding to electron transitions from the ground state to several excited states of Sm3+ were observed. The most intense absorption peak corresponding to the 6Hs/2 ^ 4F7/2 transition was located at 405 nm. For various RE:SSB no spectral changes of Sm3+ absorption bands were observed. All characteristic absorption transitions for other RE3+ were also observed and labeled with their corresponding energy levels. In order to evaluate the emission cussed clearly by Sm3+ ions, the PL excitation spectra were recorded for the 649 nm emission, hence the excitation wavelength 407 nm was chosen to record PL spectra. No shifts or spectral changes of Sm3+ emission peaks were observed for all RE:SSB, excepting Eu:SSB. It is due to the high luminescence of Eu3+ excited by 407 nm light. The two strongest Sm3+ fluorescence peaks are located at 605 and 649 nm, which correspond to relaxation from 4Gs/2 to 6H7/2 and 6Hs/2 respectively. Comparing Sm+3 fluorescence intensities for various RE:SSB one can conclude that doping with lanthanides with higher atomic number leads to lower Sm+3 fluorescence intensity (table 1). The Kurtz-Perry powder test showed that in all grown crystals the phase matching is achieved, and all they have high SHG efficiencies (table 1) excepting Gd;SSB. The nonlinear susceptibility depends on the material density, and therefore on molar mass of constituents, RE/Sm/Sc ratio and the unit cell volume. The location and orientation of [BO3] unites in crystals also effect. All RE:SSB compounds are monoclinic, but the point group still needs to be clarified. Furthermore, the composition and unit cell parameters have to be measured. Thus, at this stage, there is no enough information to explain the low deff(Gd;SSB). The relatively lower SHG efficiencies for Dy:SSB and Er:SSB could be explained by absorption at the pump and second harmonic wavelengths respectively.
RE Eu Gd Tb Dy Ho Er Tm Yb
Xem (nm) 605 nm 100 73 78 32 23 27 21 14
649 nm 100 82 92 39 22 30 25 16
deff/defl(LBQ) 0,9541 0,4572 0,8416 0,7624 0,9201 0,7733 0,8575 0,8988
This work was supported by the RSF project (№ 23-19-00617).
[1] A. B. Kuznetsov, K. A. Kokh, N. G. Kononova et. al. Polymorphism in SmSc3(BO3)4: Crystal structure, luminescent and SHG properties, J. Alloys Compd, 851, Art. No. 156825, (2021).
[2] Kurtz S.K. and Perry T.T. A Powder Technique for the Evaluation of Nonlinear Optical Materials, J. Appl. Phys. 39, 3798-3813, (1968).
