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

Abstract

Single crystals of SmAl3(BO3)4 were synthesized by the group growth on seeds method. The crystal structure was solved using a single-crystal experiment and the purity of the bulk material was proved by the Rietveld method. This borate crystallizes in the monoclinic C2/c space group with unit-cell parameters a = 7.2386 (3), b = 9.3412 (5), c = 11.1013 (4) Å and β = 103.2240 (10)°. IR and Raman spectroscopic analyses confirmed the monoclinic structure of SmAl3(BO3)4. Under 532.1 nm excitation, luminescence spectra exhibit bands assignable to the transitions from 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2. The similarity of the luminescence spectra of the trigonal and monoclinic polymorphs is explained by the minor role of Sm—O bond distortion and the primary role of rotational distortion of SmO6 octahedra. The smaller covalency of the Sm—O bond in alumoborates is deduced in comparison with galloborates. Calorimetric measurements did not reveal high-temperature structural phase transitions up to a temperature of 720 K.

Stacking Sequences of Coherent EuAl3(BO3)4 Polymorphs Define Local Eu3+ Symmetry and Control Access to Quantum Information Storage

“…When using 70 wt % flux, many smaller and thin hexagonal crystals were produced (Figure a). Single-crystal XRD showed that these smaller hexagons matched the C 2/ c polymorph previously observed in bulk single crystals of PrAl 3 (BO 3 ) 4 , NdAl 3 (BO 3 ) 4 , and SmAl 3 (BO 3 ) 4 . It is not surprising then that the structure type could accommodate Eu 3+ cations.…”

“…Single-crystal XRD showed that these smaller hexagons matched the C2/c polymorph previously observed in bulk single crystals of PrAl 3 (BO 3 ) 4 , 22 NdAl 3 (BO 3 ) 4 , 33 and SmAl 3 (BO 3 ) 4 . 34 It is not surprising then that the structure type could accommodate Eu 3+ cations. Data from the single-crystal XRD run are provided in Table 1.…”

Bright Red-Emitting Ca3LuAl3B4O15:Ce3+,Sm3+ Phosphors with High Thermal Stability for Elevating the Color Rendering of Near-Ultraviolet-Based White-Light-Emitting Diodes

“…Aside from that, selecting the suitable host material is crucial for the production of high-performance phosphors. Borates are appropriate host materials because of the low temperature required for their synthesis and exceptional thermal and chemical stability. − It can be inferred that the structure of Ca 3 LuAl 3 B 4 O 15 (CLAB) is similar to that of Ca 3 Y­(AlO) 3 (BO 3 ) 4 . The luminescence features of CLAB have been recently described by various researchers. − …”

Crystal Structure of Bismuth-Containing Samarium Iron–Aluminium Borates Sm1−xBixFe3−yAly(BO3)4 (x = 0.05–0.07, y = 0–0.28) in the Temperature Range of 25–500 K

“…Most rare-earth aluminium borates, RAl 3 (BO 3 ) 4 , also have a structure type of mineral huntite CaMg 3 (CO 3 ) 4 described by space group R32. However, monoclinic modifications (space group C2/c or C2) were discovered for RAl 3 (BO 3 ) 4 (R = Pr, Nd, Sm, Eu, Gd, Tb, Ho) crystals and the polytype nature of phases R32, C2/c, and C2 was demonstrated [21][22][23], similar to that in rare-earth chromium borates [24]. Trigonal huntite phase R32 may be present in a monoclinic view in accordance with the known transformation of rhombohedral R-cell to monoclinic C-cell [23].…”

“…Incorporation of Bi in the RFe 3 (BO 3 ) 4 structure lowered the R32→P3 1 21 transition temperature; however, other structural features associated with bismuth addition have not been identified [29,32]. RAl 3 (BO 3 ) 4 single crystals were grown using the solution-in-melt technique, with different fluxes or annealing of precursors [21][22][23]33,34]. The formation of monoclinic or trigonal phases was dependent on growth conditions, specifically on the crystallization temperature [22].…”