X-ray powder diffraction studies and thermal behaviour of NaK2B9O15, Na(Na.17K.83)2B9O15, and (Na.80K.20)K2B9O15

R. Bubnova, B. Albert, M. Georgievskaya, M. Krzhizhanovskaya, K. Hofmann, S. Filatov

Результат исследований: Научные публикации в периодических изданияхстатьярецензирование

10 Цитирования (Scopus)

Аннотация

The crystal structures of NaK2B9O15 (a = 9.1158 (1) Å, b = 6.6246 (1) Å, c = 20.6812 (3) Å, β = 94.080 (1) °, Rp = 0.047, Rwp = 0.059, RB = 0.026), Na(Na.17K.83)2B9O15 (a = 9.0559 (1) Å, b = 6.6170 (1) Å, c = 20.5833 (3) Å, β = 94.228 (2) °, Rp = 0.053, Rwp = 0.068, RB = 0.026), and (Na.80K.20)K2B9O15 (a = 9.1534 (1) Å, b = 6.6296 (1) Å, c = 20.7422 (3) Å, β = 94.071 (1) °, Z = 4, Rp = 0.041, Rwp = 0.052, RB = 0.023) were refined in the monoclinic space groups P21/c(Z = 4) using X-ray powder diffraction data and the Rietveld method. These nonaborates are isostructural to K3B9O15. Their crystal structure consists of a three-dimensional open framework built up from three crystallographically independent triborate groups. The alkali metal cations are located on three different sites in the voids of the framework. High-temperature X-ray diffraction studies show that NaK2B9O15 decomposes at about 700 °C in accordance with the peritectic reaction NaK2B9O15↔K5B19O31+liquid. The thermal expansion of NaK2B9O15 and Na(Na.17K.83)2B9O15 is highly anisotropic. A similarity of the thermal and compositional (Na-K substitution) deformations of NaK2B9O15 is revealed: heating of NaK2B9O15 by 1 °C leads to the same deformations of the crystal structure as increasing the amount of K atoms in (Na1-xKx)3B9O15 by 0.04 at% K.

Язык оригиналаанглийский
Страницы (с-по)2954-2963
Число страниц10
ЖурналJournal of Solid State Chemistry
Том179
Номер выпуска9
DOI
СостояниеОпубликовано - 1 сен 2006

Предметные области Scopus

  • Электроника, оптика и магнитные материалы
  • Керамика и композитные материалы
  • Физика конденсатов
  • Физическая и теоретическая химия
  • Неорганическая химия
  • Химия материалов

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Подробные сведения о темах исследования «X-ray powder diffraction studies and thermal behaviour of NaK<sub>2</sub>B<sub>9</sub>O<sub>15</sub>, Na(Na<sub>.17</sub>K<sub>.83</sub>)<sub>2</sub>B<sub>9</sub>O<sub>15</sub>, and (Na<sub>.80</sub>K<sub>.20</sub>)K<sub>2</sub>B<sub>9</sub>O<sub>15</sub>». Вместе они формируют уникальный семантический отпечаток (fingerprint).

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