High-temperature order–disorder phase transition in nacaphite, Na2CaPO4F

Результат исследований: Научные публикации в периодических изданияхстатья

6 Цитирования (Scopus)

Аннотация

© 2015 Springer-Verlag Berlin Heidelberg The thermal behavior of nacaphite, Na2CaPO4F, was studied by the powder high-temperature X-ray diffraction method. A monoclinic-to-orthorhombic phase transition has been observed at 330 °C associated with the appearance of the Ca/Na disorder at one of the two crystallographically inequivalent Na sites. At room temperature, nacaphite is monoclinic, P21/c, a = 13.3185(14), b = 7.0964(8), c = 10.6490(11) Å, β = 113.526(1)°, V = 922.81(17) Å3. The structure is based upon one-dimensional antiperovskite units consisting of face-sharing [FNa4Ca2]7+ anion-centered octahedra running parallel to the c axis. The structure is fully ordered and contains two Ca and four Na sites. The crystal structure of the high-temperature modification [refined by Rietveld method (RB 0.025) at 400 °C from the powder X-ray diffraction data] is orthorhombic, Pnma, a = 5.4123(1), b = 7.1196(1), c = 12.3171(1) Å, V
Язык оригиналаанглийский
Страницы (с-по)671-676
Число страниц6
ЖурналPhysics and Chemistry of Minerals
Том42
Номер выпуска8
DOI
СостояниеОпубликовано - 2015

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