New triple molybdate Rb₂AgIn(MoO₄)₃: synthesis, framework crystal structure and ion-transport behaviour

Abstract

A new triple molybdate, Rb2Ag1+3x In1–x (MoO4)3 (0 ≤ x ≤ 0.02), was found in the course of a study of the system Rb2MoO4–Ag2MoO4–In2(MoO4)3 and was synthesized as both powders and single crystals by solid-state reactions and spontaneous crystallization from melts. The structure of Rb2Ag1+3x In1–x (MoO4)3 (x ≈ 0.004) is of a new type crystallizing in the centrosymmetric space group R\overline{3}c [a = 10.3982 (9), c = 38.858 (4) Å, Z = 12 and R = 0.0225] and contains (In,Ag)O6 octahedra and distorted Ag1O6 trigonal prisms linked by common faces to form [Ag(In,Ag)O9] dimers connected to each other via MoO4 tetrahedra into an open three-dimensional (3D) framework. Between two adjacent [Ag(In,Ag)O9] dimers along the c axis, an extra Ag2O6 trigonal prism with about 1% occupancy was found. The Ag1O6 and Ag2O6 prisms are located at levels of z ≈ 1/12, 1/4, 5/12, 7/12, 3/4 and 11/12, and can facilitate two-dimensional ionic conductivity. The 12-coordinate Rb atoms are in the framework cavities. The structure of Rb2AgIn(MoO4)3 is a member of the series of rhombohedral 3D framework molybdate structure types with a ≈ 9–10 Å and long c axes, which contain rods of face-shared filled and empty coordination polyhedra around threefold axes. Electrical conductivity of ceramics is measured by impedance spectroscopy. Rb2AgIn(MoO4)3 undergoes a `blurred' first-order phase transition at 535 K with increasing electrical conductivity up to 1.1 × 10−2 S cm−1 at 720 K. Thus, the compound may be of interest for developing new materials with high ionic conductivity at elevated temperatures.

Climato-Economic Origins of Variations in Uniqueness of Nickname on Sina Weibo

“…In Varnum’s studies 1 and 2, the percentages of the most common baby names were higher in less individualistic regions (eastern regions) than in the more individualistic ones (western frontier regions) in both the United States and Canada separately ( Varnum and Kitayama, 2011 ). Others found that frontier experiences during 1790–1890 were associated with giving babies uncommon names at the county level in the United States ( Bazzi et al, 2020 ). Overall, fitting in or standing out from a group in the practice of naming babies has been strongly proven to be a facet of I-C.…”

A Comparison of Penalized Maximum Likelihood Estimation and Markov Chain Monte Carlo Techniques for Estimating Confirmatory Factor Analysis Models With Small Sample Sizes

“…First, one could use robustly estimated covariance matrices as input for Bayesian CFA models. In this case, robust standard errors must also be applied in Bayesian estimation because the model is misspecified ( Müller, 2013 ; Walker, 2013 ; Bissiri et al, 2016 ). Second, models with more flexible distributions for the latent factors and residuals could be applied ( Lin et al, 2018 ).…”

New triple molybdate and tungstate Na5Rb7Sc2(XO4)9 (X = Mo, W)

“…R32 and together with their formula and structural analogues Ag5Rb7Sc2(ХO4)9 (Х = Mo, W), Na5Cs7Ln2(MoO4)9 (Ln = Tm, Yb, Lu) belong to the series of rhombohedral triple molybdates and tungstates with а = 9-10 Å and long c-parameter, more than 20 Å; many of those have noticeable ionic conductivity at elevated temperatures [19][20][21].…”

“…Triple molybdates Na25Cs8R5(MoO4)24 (R = In, Sc or Fe) [13,14] and Na10Cs4Со5(MoO4)12 [15], built on the basis of alluaudite (Na,Ca)Mn(Fe,Mg)2(PO4)3, M1-xA1-xR1+x(MoO4)3 [16,17] with the NASICON-type structure, K5ScHf(MoO4)6 [18] with the K5InHf(MoO4)6-type structure, and AgRb2In(MoO4)3 [19], Ag3Rb9Sc2(WO4)9…”