Influence of rare earth cation size on the crystal structure in rare earth silicates, Na2RESiO4(OH) (RE = Sc, Yb) and NaRESiO4 (RE = La, Yb)

Abstract

= 5. For n = 2-13, the transition or switch from weak (primarily dipole-dipole-type) inter-monomer interactions to a preference for polar covalent bonding occurs within n = 5-9. Thermodynamic evidence for this transition is provided. The results demonstrate a significant risk associated with crystal structure prediction from the ground up (i.e., based on bonding patterns in small clusters). The path from monomers through extended solids with increasing n is discussed to be associated with transitions in structure and bonding that are not anticipated by the bonding in small clusters. 2O3 with 98% H2SO4 (porcelain crucible, 230 C resp. 210 C, 5 d; cooling to 100 C at a rate of 2 C/h, 89 and 91% yield for the K and Cs compound, resp.). KSb(SO 4 ) 2 crystallizes in the monoclinic space group P2 1 /c (Z = 4, single crystal XRD), and CsSb(SO 4 ) 2 in the orthorhombic space group P2 1 2 1 2 1 (Z = 4). Both compounds show the Sb 3+ cations in a seesaw-type coordination of O atoms from different anions, but exhibit complex 2D and 1D linked anionic structures. The alkali cations are located between the layers or chains. The band gaps are estimated to be 4.64 eV for KSb(SO 4 ) 2 and 4.68 eV for CsSb (SO 4 -Eu 7 Cd 4 Sb 8-x As x (x = 2, 3, 4, and 5) solid solutions are prepared from the elements in a molten Sn flux (alumina crucible in evacuated silica tubes, 1. 600 C, 6 h; 2. 1000 C, 96 h; cooling to 600 C at a rate of 5 C/h). The title phases crystallizes in the I-centered monoclinic space group I2/m (Z = 4, single crystal XRD) and contain parallel double pentagonal tubes resulting from Cd-Pn (Pn: Sb, As) and Pn-Pn bonding. These double pentagons are formed through corner sharing of Cd-centered CdPn 4 tetrahedra and a Pn-Pn interaction of two adjacent CdPn 4 tetrahedra. Theoretical calculations predict that Sb-rich compounds should be metallic or semimetallic and that they should become more insulating as As levels increase. Members of the solid-solution order ferromagnetically between 5 and 6 K and exhibit electrical resistivities ranging from 0.57 (50 K) to 26 m·cm (300 K) which increase with As levels. -Single crystals of Na 2 ScSiO 4 (OH) (I) and Na 2 YbSiO 4 (OH) (II) are prepared by hydrothermal reaction of a 2:1 molar mixture of Na 2 SiO 3 and Sc 2 O 3 (Yb 2 O 3 ) in a NaOH based hydroflux (autoclave, 230 C, 48 h; cooling to 80 C at a rate of 0.1 C/min for (I) or quenching to 25 C). Crystals of NaLaSiO 4 (III) and NaYbSiO 4 (IV) are grown from La 2 O 3 (Yb 2 O 3 ), Na 2 CO 3 , and SiO 2 using a NaF/NaCl eutectic flux (Ag crucible, 900 C, 48 h). Compounds (I) to (II) crystallize in the orthorhombic space group Pca2 1 (Z = 8, single crystal XRD) while the structure of (III) is refined in the orthorhombic space group Pca2 1 (Z = 4) and (IV) in the orthorhombic space group Pnma (Z =4 [CuCl 4 ] crystallizes in the orthorhombic space group P2 1 2 1 2 1 with Z = 8 (single crystal XRD). Its asymmetric unit consists of four unique Et 2 cations and three unique anions. Two of the three Cu atoms adopt a d...

Progress in Sodium Silicates for All‐Solid‐State Sodium Batteries—a Review

“…[73] Table 2 includes the synthesis method and conductivity of some more silicates developed. [53,54,60,[62][63][64][65][66][73][74][75]79,81,82,[98][99][100][101][113][114][115][116][117][118][119][120][121][122][123][124] High-ionic conductivity at RT is achieved by the silicate doped with phosphorous, Na 5.2 Y 0.8 P 0.4 Si 3.6 O 12.0 . [98] 4.2.…”

Syntheses, crystal structures, and comparisons of rare-earth oxyapatites Ca2 RE 8(SiO4)6O2 (RE = La, Nd, Sm, Eu, or Yb) and NaLa9(SiO4)6O2

“…The general formula of silicate oxyapatites containing rareearth metals along with alkalis or alkaline earths (without OH À ) is A 1+x RE 9-x (SiO 4 ) 6 O 2 [0 x 1; A = Li (Setoguchi, 1990;Ito, 1968), Na (Setoguchi, 1990;Ito, 1968), Ca (Fahey et al, 1985;Lambert et al, 2006;Ito, 1968), Ba (Lambert et al, 2006;Ito, 1968), Sr (Lambert et al, 2006;Ito, 1968;Latshaw et al, 2016), Mg (Ito, 1968), Mn (Ito, 1968), Pb (Ito, 1968); Ln = La (Lambert et al, 2006;Ito, 1968), Ce (Massoni et al, 2018), Pr (Leu et al, 2011;Sakakura et al, 2010), Nd (Fahey et al, 1985;Setoguchi, 1990;Ito, 1968;Latshaw et al, 2016), Sm (Ito, 1968), Eu (Setoguchi, 1990), Gd (Ito, 1968), Tb (Leu et al, 2011), Dy (Ito, 1968), Er (Ito, 1968), Tm (Leu et al, 2011), Lu (Ito, 1968), Yb (Latshaw et al, 2016), and Y (Ito, 1968)]. In this work, oxyaptites with different A and RE are abbreviated as A-RE [e.g.…”

Oxohydroxo‐Tellurates(VI) K2[TeO2(OH)4] and K2[Fe2TeO6(OH)2] ⋅ 2H2O from Alkaline Hydroflux

“…The work of zur Loye [15,16,[19][20][21][22][23][24][25][26][27][28] and the recent contributions by us [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] give an impression of the potential of the hydroflux method. In just a few years, almost 100 new compounds were found in already extensively explored systems.…”