The crystal structure of sodium diborate, Na₂O.2H₂O₃

The crystal structure of α sodium triborate, α-Na2O.3H2O3

“…Two other anhydrous sodium polyborates have been studied, and the coordinations of sodium in these compounds are as follows. In sodium diborate a sixfold coordination is found for three of the four non-equivalent sodium atoms, the last being sevenfold coordinated (Krogh-Moe, 1974). As mentioned previously by Krogh-Moe (1972b), the table of sodium-oxygen distances reported by Hyman, Perloff, Mauer & Block (1967) for sodium tetraborate is not complete.…”

“…This serves to emphasize the several ways in which the borate anion groups may polymerize for a given stoichiometry. Such differences in structures have previously been noted for the diborates (Krogh-Moe, 1974). It is tempting to relate the evident range of possible structures to the strong glass-forming ability of these compounds.…”

Crystal Structure of a New Form of Sodium Octoborate β-Na2B8O13

“…Several compounds were reported in the Na 2 O-B 2 O 3 binary system (2)(3)(4). Among them, the structures of Na 3 BO 3 (5), Na 4 B 2 O 5 (6), NaBO 2 (7), Na 2 B 4 O 7 (8), a-NaB 3 O 5 (9), b-NaB 3 O 5 (10), and aNa 2 B 8 O 13 (11,12) were established. In the binary system Na 2 O-B 2 O 3 (2-4), the borate Na 2 O Á 4B 2 O 3 (Na 2 B 8 O 13 ), called octoborate, was reported to exist in two forms.…”

Examples of Hartmann–Hahn Match Conditions for CP/MAS between Two Half-Integer Quadrupolar Nuclei

“…These compounds are promising candidates for the CP technique due to short distances between the quadrupolar nuclei, which are about 0.3 nm or less as determined by X-ray crystallography (22)(23)(24). Given the considerations mentioned above, we have chosen the fastest readily achievable spinning speed for our apparatus ( R ϭ 10 kHz), and radiofrequency field strengths both less than and greater than the spinning speed.…”