RIETVELD REFINEMENT OF SYNTHETIC MONOCLINIC NaBSiO4

Abstract

A full-pattern X-ray powder-diffraction refinement reveals that NaBSiO 4 prepared at 6 GPa and 700°C crystallizes in space group P2 1 /n with the structure of beryllonite, NaBePO 4 . With a 7.9845(5), b 7.6969(5), c 13.9432(9) Å, ␤ 90.081(6)° and V 856.89(2) Å 3 , NaBSiO 4 has the smallest unit-cell volume of all known compounds with the beryllonite structure. A naturally occurring counterpart could be the unnamed mineral UK53 from Mont Saint-Hilaire, Quebec, Canada. The crystal structure of monoclinic NaBSiO 4 is closely related to that of the hexagonal mineral malinkoite, with the same chemical composition. The structural differences are mainly caused by variant arrangements of two kinds of six-membered rings made up of alternating (BO 4 ) and (SiO 4 ) tetrahedra.Keywords: beryllonite, synthetic NaBSiO 4 , malinkoite, stuffed tridymite. SOMMAIREUn affinement du spectre de poudre entier en diffraction X du composé NaBSiO 4 , synthétisé à 6 GPa et 700°C, a montré qu'il cristallise dans le groupe d'espace P2 1 /n avec la structure de la béryllonite (NaBePO 4 ). Avec les paramètres de maille a 7.9845(5), b 7.6969(5), c 13.9432(9) Å, ␤ 90.081(6)° et V 856.89(2) Å 3 , le NaBSiO 4 possède la maille la plus petite de tous les composés à structure de type béryllonite. Un analogue naturel pourrait être le minéral sans nom UK53 de Mont Saint-Hilaire, au Québec. La structure cristalline de notre composé monoclinique est intimement liée à celle de la malinkoïte, hexagonale, dont la composition est aussi NaBSiO 4 . Les différences structurales sont essentiellement dues aux divers arrangements des deux types d'anneaux à six membres constitués d'une alternance de tétraèdres (BO 4 ) et (SiO 4 ).

Nepheline crystallization in boron-rich alumino-silicate glasses as investigated by multi-nuclear NMR, Raman, & Mössbauer spectroscopies

“…If adjacent layers are mirror images of each other, the arrangement is known as eclipsed or cis, such as in nepheline or tridymite. If adjacent layers are rotated 180° around each other and shifted laterally, the arrangement is known as staggered or trans, such as in kalsilite (KAlSiO 4 ) and malinkoite (NaBSiO 4 ) [38].…”

“…Raman data suggests the presence of B-Na enriched and Al-Si enriched clusters in glasses with the highest B tested, NaAl 0.2 B 0.8 SiO 4 [26]. Crystalline malinkoite is hexagonal and contains B(IV) and Si tetrahedra linked in 6-membered rings with two different "up"/"down" configurations and Na in the ditrigonal channels [65], but monoclinic forms of NaBSiO 4 have also been produced with differing arrangement of "up"/"down" tetrahedra [38].…”

Chiral edge-shared octahedral chains in liskeardite, [(Al,Fe)32(AsO4)18(OH)42(H2O)22]·52H2O, an open framework mineral with a pharmacoalumite-related structure

“…Electron microprobe analyses gave small amounts (0.2 to 0.9 wt.%) of Na, K and Cu, which could all occupy the site. Hydrated Cu is reported to be held strongly in zeolites with medium-sized nanopore channels (Ferreira et al, 2012) and octahedrally coordinated Na with the same range of bond lengths (2.2 to 2.6 Å ) is reported in NaBSiO 4 (Graetsch and Schreyer, 2005). The local changes in bond lengths required for these different sized cations are well within the large mean square displacements of the ligands.…”

NaCa5BO3(SiO4)2 with Interesting Isolated [BO3] and [SiO4] Units in Alkali- and Alkaline-Earth-Metal Borosilicates

“…Nevertheless, as shown in Figure S2, the Si–O structures display luxuriant diversity. (1) For the title compound NaCa 5 BO 3 (SiO 4 ) 2 , LiBSiO 4 , NaBSiO 4 , , Ca 2 B 2 SiO 7 , Cs 2 B 4 SiO 9 , and CsB 3 SiO 7 , they all contain isolated [SiO 4 ] tetrahedra. Only in NaCa 5 BO 3 (SiO 4 ) 2 , it includes isolated [BO 3 ] simultaneously.…”