JaLCDOI 10.18926/ESR/13936
フルテキストURL ESR_3_57.pdf
著者 Okamoto Yasuhiko| 河原 昭|
抄録 The syntheses of kaliophilite have been carried out from the starting materials of near kalsilite compotions (KAISiO4), of which the AI2O3/SiO2 ratio is greater than 1/2. The X-ray powder deffraction pattern fit well to those of previous investigators. The crystal structure of synthetic kaliophilite was proposed by using the model consisting of four different types of kalsilite structure. The positions and intensities of the X-ray powder pattern were able to be explained on the basis of these four domains, belonging to thr twinning by merohedory. As a result of the conditions of the syntheses, it may be supposed that the violation of the AI-O-AI avoidanice rule can possibly exist along the domain boundaries.
キーワード kaliophilite kalsilite synthese domain boundary
出版物タイトル Okayama University Earth Science Report
発行日 1996-09-20
3巻
1号
開始ページ 57
終了ページ 64
ISSN 1340-7414
言語 English
著作権者 岡山大学地球科学研究報告編集委員会
論文のバージョン publisher
NAID 120002310557
JaLCDOI 10.18926/ESR/13919
フルテキストURL ESR_4_41.pdf
著者 Okamoto Yasuhiko|
抄録 Kalsilite, a polymorph of KAISiO4 is an end member of nepheline-kalsilite series and the mineral was syn-thesized by hydorhermal methods. The synthetic kalsilite is hexagonal, P63, with a=5.151(5), c=8.690(8) A. The structure was refined by full-matrix least-squares methods to a R-value 0.084, using 373 observed reflections. The obtained structure agrees well with those of the natural and the alkali-exchanged specimens reported in the previous literatures. The oxygen atoms are disordered at two mirror-equivalent sites, constructing the domain structure. The average domain structure shows P63mc symmetry and the strctural relation between the two P63 structure corresponds to the twinning by merohedry. The domain structure was considered to be caused accompanied with the high-low inversion of the kalslite structure. Heating experiments of kalsilite reveal that the X-ray powder pattern changes at 865℃, and that cell dimensions vary discontinuously at this temperature. It was confirmed that kalsilite underwent a displacive transition like those observed in quartz or tridymite. The high-form is refered as 'high-kalsilite', and a possible simulate model is proposed. The structure of the high-kalsilite at 950℃ was refined byfull-matrix least-squares methods to a R-value 0.095, using 115 observed reflections. The high-kalsilite is also hexagonal, P63mc or P63/mmc, with a=5.288(1), c=8.628(5) A at 950℃. The structure almost prefectly coincides with that of the simulated model. Based on the interatomic distances, the distribution of silicon and aluminum atoms is found to be or-dered and the space group is determined to be P63mc. Kaliophilite and the related orthorhombic from, polymorphs of KAISiO4, were synthesized by dry method. The synthetic kaliophilite (kaliophilite-H2) is hexagonal with a=5.17(1), c=8.49(3) A, and the orthorhombic KAISiO4 (kaliophilite-O1) is orthormbic with a=9.01(1), b=15.60(2), c=8.53(4) A. Detailed examina-tion of the obtained powder patterns together with that of simulated model indicates that the kaliophilite-H2 has a disorderd structure of four types of the low-kalsilite. The structure was refined by the X-ray powder pattern-fitting method (Rietvelt method) to a R-value 0.121.
キーワード kalsilite kaliophilite faldspathoid systheses crystal structre
出版物タイトル Okayama University Earth Science Report
発行日 1997-09-20
4巻
1号
開始ページ 41
終了ページ 72
ISSN 1340-7414
言語 English
著作権者 岡山大学地球科学研究報告編集委員会
論文のバージョン publisher
NAID 120002310427