The impact of cationic isomorphism on the optical properties of a solid solution based on TbAb(BO3)4
A. Kuznetsov'*, A. Jamous1'2, M. Rachmanova3, A. Kokh1
1- Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk 630090, Russia 2- Tomsk State University, Tomsk 634050, Russia 3- Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090, Russia
* ku.artemy@igm.nsc.ru
RM3(BO3)4 (R=Y, La-Lu, M=Al, Ga, Cr, Fe), orthoborates are excellent compounds for optical applications. These compounds, known as huntites, are isotypical to the mineral CaMg3(CO3)4, which crystallizes in the R32 space group [1]. Among the huntites, the compounds with aluminum can be promising materials for nonlinear optical, phosphor, and laser applications [2]. These materials have a low of concentration quenching of luminescence compared to RBO3. In addition, they have chemical stability, mechanical strength, and unique thermal conductivity. The structural and optical properties of TbAh(BO3)4 single crystal have been studied in [3] where this crystal was explored as a new magneto-optic borate crystal. Faraday rotations and Verdet constants of TbAl3(BO3)4 crystal were measured at wavelengths of 532, 633, and 1064 nm. The article [4] shows that the maximum intensity of luminescence is observed in YAh(BO3)4:5% Tb.
Despite the large number of experimental and theoretical studies, there is a lack of data on substitution between Al3+ and Tb3+ in TbAl3(BO3)4. However, there is evidence of isomorphism in other systems, such as RAh(BO3)4 and RSc3(BO3)4, which suggests that isovalent substitutions are possible for TbAl3(BO3)4. Additionally, it is important to note that all huntite borates exhibit incongruent melting behaviors and cannot be grown directly from the melt [5]. Since the first syntheses by Blasse and Bril in 1967 [6], numerous growth methods have been proposed until the present day. However, melt-solution growth remains the most widely used method.
This work is devoted to the refinement of solid solution area for TbAl3(BO3)4 in TbBO3-(AhO3:B2O3) systems by diffusion experiments, solid-state synthesis and combustion methods. In addition, crystals of TbAl3(BO3)4 are grown from K2Mo3Oio-B2O3-Al2O3 flux. To compare emission and excitation spectra, QY and luminescence lifetimes, samples with different composition and synthesis conditions have been obtained. As a result, typical spectroscopic feature of Tb3+ is observed. There are four main bands in a wide wavelength range of 470-700 nm. These are due to transitions from the excitation state 5D4 to the ground states 7Fj (J = 6, 5, 4, 3) of the trivalent Tb ion in the host lattice. The strongest emission peak of the TbAl3(BO3)4 is centered at a wavelength of 541 nm, indicating the emission of green light. According to the data obtained by Kurtz-Perry powder test on the second harmonic generation of the TbAl3(BO3)4 compound, the intensity of the 50-100 ^m fraction is higher than that of KDP.
This work was supported by the RSF project (№ 23-19-00617).
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