Bridging the Salt-Inclusion and Open-Framework Structures: The Case of Acentric Ag₄B₄O₇X₂ (X = Br, I) Borate Halides

Abstract

An acentric borate family, Ag 4 B 4 O 7 X 2 (X = Br, I), has been prepared by slow cooling stoichiometric melts in evacuated silica ampules. Their crystal structure is comprised of two porous interpenetrating frameworks and demonstrates a further development of the "salt-inclusion" architecture toward a "covalent-inclusion" structure. The (Ag 2 X) + sublattice shows strong anharmonic vibrations. Thermal expansion is strongly anisotropic because of the presence of condensed rigid kernite boron−oxygen chains aligned perpendicular to the c axes.

Where the extraordinaries meet: a cascade of isosymmetrical superionic phase transitions and negative thermal expansion in a novel silver salt-inclusion borate halide

“…[13][14][15][16][17][18][19][20][21][22][23] Among hilgardites, iodides exhibit the greatest NLO efficiency, 24 which prompted us to look for M 3 B 6 O 10 I. Besides Na + and K + , Ag + is also a promising candidate as shown by the successful synthesis of Ag 4 B 4 O 7 X 2 (X = Br and I) 25 and Ag 4 B 7 O 12 Br, 26 which have complex architectures (Fig. S1 †).…”

Synthesis, Characterization and Optical Properties of Two Novel Metal Borates

“…Until now, only a few silver borates have been reported, including the metaborate AgBO 2 , the orthoborates Ag 3 BO 3 ‐I and Ag 3 BO 3 ‐II, two modifications of Ag 2 B 8 O 13 , AgB 3 O 5 , AgB 9 O 14 , Ag 2 B 4 O 7 , Ag 3 B 5 O 9 , two quaternary silver borates SrAg[B 7 O 12 ] and CsAg 2 [B 15 O 24 ], [17] silver borosulfate Ag[B(SO 4 ) 2 ], [18] and so on. Recently, salt‐inclusion silver halide borates have attracted much attention and several crystals have been obtained, for example, Ag 4 B 4 O 7 X 2 (X=Br, I) with strongly anisotropic thermal expansion, [16a] two noncentrosymmetric silver borate halides |Ag 4 X 2 |@[B 4 O 7 ] (X=Br, I) and Ag 3 B 6 O 10 I being a promising solid‐state electrolyte [19] . These works are mainly dedicated to the synthesis and characterization of new silver borates.…”

Li7SrScB12O24and Li7Ba0.6Ca0.4ScB12O24: two new quaternary rare-earth borates with short UV cutoff edges

“…[17][18][19][20][21][22][23][24][25][26][27][28] The structural diversity of borates is mainly attributed to the flexible coordination mode of the B atom, and there exist three coordination environments of boron, including two, three and four coordinated with oxygen atoms to form rarely seen linear BO 2 , triangular BO 3 and tetrahedral BO 4 basic units. [29][30][31][32][33][34] These B-O units can exist insularly or further condense to generate various fundamental building blocks (FBBs) by sharing common O atoms including isolated clusters, chains, rings, sheets, and framework structures, offering the possibility for producing specific structures, which can be functionalized for targeted applications. [35][36][37][38][39][40][41] As we all know, a short ultraviolet (UV) cutoff edge is one of the most crucial properties for ultraviolet (UV) or deep ultraviolet (DUV) optical crystals.…”