Hydrothermal synthesis, structure, and property characterization of rare earth silicate compounds: NaBa3Ln3Si6O20 (Ln = Y, Nd, Sm, Eu, Gd)

Abstract

A series of new lanthanide (Ln) silicates have been synthesized using high temperature hydrothermal techniques, and structurally characterized using single crystal and powder X-ray diffraction. The compounds have the general formula NaBa 3 Ln 3 Si 6 O 20 (Ln = Y, Nd, Sm, Eu, Gd), and crystallize in the space group Ama2 (No.40). As a representative example, the unit cell parameters of NaBa 3 Gd 3 Si 6 O 20 are a = 14.731(3) Å, b = 23.864(5) Å, c = 5.5449(11) Å and Z = 4. The title compounds adopt a three dimensional polar acentric framework made of Ln−O−Si bonding. The framework is comprised of LnO 8 and LnO 7 units forming edge-sharing infinite chains along the c-axis. These oxy-bridged infinite chains are also linked by [Si 4 O 13 ] tetrasilicate and [Si 2 O 7 ] disilicate units to form the three-dimensional framework structure, with Ba 2+ and Na + cations residing inside channels of the framework. The polarity in the structure is imparted by the unusual tetrasilicate arrangement. The luminescence and magnetic properties were investigated on selected compounds. The temperature dependent magnetic susceptibility measurements on the Nd, Sm, and Gd derivatives reveal a Curie-Weiss behavior with an antiferromagnetic coupling parameter. For the Eu-derivative, the temperature dependent magnetic susceptibility deviates significantly from Curie-Weiss behavior. Luminescence properties of NaBa 3 Eu 3 Si 6 O 20 and NaBa 3 Sm 3 Si 6 O 20 compounds exhibited the characteristic transitions of Eu 3+ (5 D 0 → 7 F J , J = 0-4) and Sm 3+ (4 G 5/2 → 6 H J , J = 5/2, 7/2), respectively, leading to strong visible red and orange emissions, respectively.

Orthoborates LiCdRE5(BO3)6 (RE = Sm–Lu and Y) with Rare-Earth Ions on a Triangular Lattice: Synthesis, Crystal Structure, and Optical and Magnetic Properties

“…The temperature-dependent molar magnetic susceptibilities and the inverse susceptibilities of LiCdRE 5 (BO 3 ) 6 (RE = Sm–Yb) are given in Figure . At elevated temperatures, the rare-earth borates obey Curie–Weiss law except for the Sm and Eu analogues. − As reported in many Sm 3+ compounds, LiCdSm 5 (BO 3 ) 6 also exhibits Van Vleck-type paramagnetism. , where δ = 27λ/110 kT and λ and k are the spin–orbit coupling (SOC) and Boltzmann constants, respectively. The deduced SOC constant is obtained as 450 K, in good accordance with the experimental value (444 K) from the fluorescence spectra of the ground state (blue curve in Figure b).…”

Blue-green tunable color of Ce3+/Tb3+ coactivated NaBa3La3Si6O20 phosphor via energy transfer

“…In the refinement, an initial structure model and atomic positions of NaBa 3 Eu 3 Si 6 O 20 were adopted for the structure refinement3536. NaBa 3 La 3 Si 6 O 20 crystallizes in the noncentrosymmetric space group A ma2 and unit cell parameters are obtained as a = 14.9226(4) Å, b = 24.5215(5) Å and c = 5.6241(2) Å, which are slightly larger than those of NaBa 3 Eu 3 Si 6 O 20 due to large ionic radius of La 3+ ion37.…”

High-pressure synthesis, crystal structure and photoluminescence properties of a new terbium silicate: Na2Tb1.08Ca2.92Si6O18H0.8

“…As a few examples, Huang et al documented the HP synthesis of a new europium silicate Cs 3 -EuSi 6 O 15 , which consists of loop-branched vierer double chains of silicate with four-, six-, and eight-membered rings; 3 Zhao et al reported the HP synthesis of three new lanthanide silicates based on anionic silicate chain, layer, and framework. 14 Liu's group synthesized a number of lanthanide-containing silicates under HP conditions and reported their structural features.…”

“…[1][2][3][4][5] Due to their high thermal stability and tunable optical properties, the lanthanide-containing silicates attract much interest as candidates of optical materials. [6][7][8] In 1997, Rocha et al reported a microporous sodium yttrium silicate Na 4 K 2 Y 2 Si 16 O 38 -$10H 2 O. 9 Since then a series of microporous lanthanide silicates have been successfully prepared.…”