Structural, Electronic and Vibrational Properties of YAl3(BO3)4

Abstract

The crystal structure of YAl3(BO3)4 is obtained by Rietveld refinement analysis in the present study. The dynamical properties are studied both theoretically and experimentally. The experimental Raman and Infrared spectra are interpreted using the results of ab initio calculations within density functional theory. The phonon band gap in the Infrared spectrum is observed in both trigonal and hypothetical monoclinic structures of YAl3(BO3)4. The electronic band structure is studied theoretically, and the value of the band gap is obtained. It was found that the YAl3(BO3)4 is an indirect band gap dielectric material.

Monoclinic SmAl3(BO3)4: synthesis, structural and spectroscopic properties

“…3. The existence of an empty gap in the region of 1050-1200 cm À1 in the IR spectrum is in accordance with the results of Oreshonkov et al (2020). We did not find any published Raman spectra from monoclinic ReAl 3 (BO 3 ) 4 samples.…”

“…The spectral profile below 800 cm À1 (Fig. 4) has a more complex form in comparison with other ReAB borates (Oreshonkov et al, 2020), this region of the spectra containing (in order of decreasing frequency) the 2 and 4 bending modes of [BO 3 ] 3À ions, translations of Al 3+ and [BO 3 ] 3À , and translations of Sm 3+ ions (Borovikova et al, 2013).…”

“…1050 and 1200-1450 cm À1 , respectively. The region for the [BO 3 ] 3À symmetric stretching vibrations should contain four lines in the case of monoclinic ReAl 3 (BO 3 ) 4 (Oreshonkov et al, 2020) and three of them are clearly seen in Fig. 3.…”

“…In the case of ReAl 3 (BO 3 ) 4 borates with a huntite-like structure, the IR-and Raman-active modes should be listed as À IR = 12A 2 + 19E and À Raman = 7A 1 + 19E, respectively. Thus, the vibrational spectra for monoclinic SmAl 3 (BO 3 ) 4 is more complicated than for trigonal ReAl 3 (BO 3 ) 4 (Oreshonkov et al, 2020), because of the lower symmetry and the large number of active modes. In the structure of monoclinic SmAB, the B atoms occupy two crystallographically independent positions with C 1 site symmetry (Table S3 in Non-polarized Raman spectrum of the monoclinic SmAl 3 (BO 3 ) 4 single crystal.…”

“…The IR spectrum of SmAl 3 (BO 3 ) 4 , with a trigonal (R32) structure, is presented in the same work (Dobretsova et al, 2014) and additional spectral bands were described as being due to the presence of the monoclinic SmAl 3 (BO 3 ) 4 (C2/c) polytype. The proposed explanation for the extra peaks in the IR spectra is discussed by Oreshonkov et al (2020). The Raman spectra of monoclinic ReAl 3 (BO 3 ) 4 have not been published.…”