Hydrothermal Synthesis and Crystal Structure of a Mixed-Valence Bismuthate, Na₃Bi₃O₈

Abstract

Four types of bismuth oxides, Na3Bi3O8, NaBiO3, α-Bi2O3, and ε-Bi2O3, were obtained by hydrothermal reactions using NaBiO3·nH2O in NaOH solution. The crystal structure of a new phase (Na3 Bi3+)­Bi2 5+O8 ((Na0.75Bi0.25)2BiO4) was determined by using single crystal X-ray diffraction data, and this compound was found to show a Na2MnCl4-related structure with a monoclinic system (space group, Pm) with the following lattice parameters: a = 5.990 (2) Å, b = 3.335 (2) Å, c = 10.108 (2) Å, and β = 91.08 (3)°. The final R-factors R 1 and wR 2 were 0.041 and 0.090 (all data), respectively. The new phase was composed of mixed valence states of Bi (Bi3+ and Bi5+, with a mean Bi valence of 4.30) with five distinct Bi sites, where two Bi5+ (Bi1 and Bi2) fully occupied the distorted octahedral sites and three Bi3+ (Bi3, Bi4, and Bi5) were statistically distributed at the split sites with Na+ (Na3, Na4, and Na5). The Na6 site is fully occupied. The distorted Bi5+O6 octahedra formed one-dimensional chains via edge-sharing along the b-axis, with the chains held by Bi3+/Na+ split sites. The structural feature except for the split distribution of Bi3+/Na+ was classified as a Na2MnCl4-type structure. DFT calculations based on a model discounting the split distribution of Bi3+/Na+ indicated that Bi 6s and O 2p orbitals form sp hybridization at the conduction band. This new mixed valence bismuth oxide exhibited photocatalytic activity for phenol degradation under visible light irradiation. In addition to Na3Bi3O8, the hydrothermal reaction using NaBiO3·nH2O in NaOH solution yielded micrometer-sized single crystals of an ilmenite-type NaBiO3 and two polymorphs of bismuth oxides with monoclinic (α-Bi2O3) and orthorhombic (ε-Bi2O3) structures, depending on the reaction temperature and NaOH concentration.

Exploring the influence of pressure-induced semiconductor-to-metal transition on the physical properties of cubic perovskites FrXCl3 (X = Ge and Sn)

“…When studying lead-free halide perovskites, researchers often look carefully into several different physical properties, such as structural, optoelectronic and mechanical ones, to better understand the difficulties involved with material applications [ [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] ]. In order to forecast the potential uses of a material, it is common practice to apply both experimental and theoretical methods of analysis [ [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , [56] , [57] , [58] , [59] ]. Most recently, there has been substantial research into the use of metal halide perovskite compounds due to their notable optoelectronic characteristics, such as their adaptable transparent bandgap, wide absorption spectrum, narrow emission width, high absorption and charge diffusion, and abundant mobile carriers with a light mass that is efficient [ 60 , 61 ].…”

Hydrostatic pressure-induced transformations and multifunctional properties of Francium-based halide perovskite FrCaCl3: Insights from first-principles calculations

“…The physical attribute of material is typically examined using both computational and experimental methods to predict its applications [ [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] ]. A material's physical qualities are perhaps influenced by its structure.…”

Hydrothermal synthesis and crystal structure of a novel double-perovskite-type bismuth oxide with 3 : 1 ordering at the B-site

“…14 Experimentally, a low-temperature hydrothermal environment of B120 1C was found to be ideal for preparing bismuth oxides with Bi 5+ and mixed Bi 5+ /Bi 3+ ions from NaBiO 3 ÁnH 2 O. [15][16][17][18][19][20] This method has been proven to be efficient for synthesizing new inorganic materials [21][22][23][24][25][26][27][28][29][30] and the striking characteristic of it is to produce Bi 5+ , as evidenced by previously synthesized bismuth oxides. 13,[15][16][17][18][19]29,31,32 In addition, the perovskite-type Ba(Bi 0.75 M 0.25 )O 3 (M = Li, Na) and Ba(Bi 0.67 M 0.33 )O 3 (M = Mg, Ca, Sr, Ba, Cd, Cu) were synthesized under high oxygen pressure, which also exhibited Bi 5+ at the B-site.…”

“…33 Several bismuth oxides containing either mixed Bi 5+ /Bi 3+ or only Bi 5+ exhibited significant photocatalytic activities under visible-light irradiation. 28,29,[34][35][36] Moreover, hydrothermally prepared single-and double-perovskite-type bismuth oxides exhibited superconductivity with relatively high transition temperatures. 4,6,7,13,30 Therefore, based on the exploration of more compounds, a novel perovskitetype bismuth oxide was developed via a facile hydrothermal reaction using NaBiO 3 ÁnH 2 O as the starting material.…”