THE DISTRIBUTION OF CHROMIUM IN CHROMIAN PUMPELLYITE FROM SARANI, URALS, RUSSIA: A TOF NEUTRON AND X-RAY RIETVELD STUDY
THE DISTRIBUTION OF CHROMIUM IN CHROMIAN PUMPELLYITE FROM SARANI, URALS, RUSSIA: A TOF NEUTRON AND X-RAY RIETVELD STUDY
复制标题
俄罗斯乌拉尔萨拉尼铬质斜长岩中铬的分布：TOF 中子和 X 射线 Rietveld 研究
DOI：
10.2113/gscanmin.45.4.837
复制
发表时间：
2007
影响因子：
0.9
通讯作者：
M. Akasaka
中科院分区：
文献类型：
--
作者：
M. Nagashima;M. Akasaka
俄罗斯乌拉尔（Sarani）的Chromian Pumpelly石材的晶体结构使用完整的飞行时间中子和X射线rietveld方法进行了改进，以研究pumply颗粒中平均化学成分的晶体化学行为。 22.06±0.39，MGO 3.95±0.37，Cr 2 O 3 14.39±1.19，Al 2 O 3 16.71±0.79，Total Fe 2 O 3 0.15 ±0.08和SIO 2 35.73±0.63 wt。％（n = 38）用X射线划分数据的CR和AL的占领为0.32（1）Cr，在X站点为0。20AL，在Y位置为0.31CR和0.69AL。精制占领的有效性和Cr是根据公式为三价的假设。尽管Cr 3+离子都出现在X和Y位点，但分布系数[（Cr/al）X/（Cr/Al）Y = 3.56]表明更强X位点比Y位点的偏好是8.8193（5），B 5.9396（3），C 19.161（1）A，β97.603（2）°和V 994.86（9） ）A 3（中子数据）和8.8132（2），B 5.9342（1），C 19.1466（3）A，β97.603（2）°和V 992.54（3）A 3（X射线数据） Y位置铝铬的铬增加了平均值y - othahedra的距离，导致a，b和c的尺寸增加。随着平均Y - O距离的增加和位点的体积而减小。形式。
The crystal structure of chromian pumpellyite from Sarani in the Russian Urals was refined using complementary time-of-flight neutron and X-ray Rietveld methods, to investigate the crystal-chemical behavior of chromium in pumpellyite. The average chemical composition of the sample is CaO 22.06 ± 0.39, MgO 3.95 ± 0.37, Cr 2 O 3 14.39 ± 1.19, Al 2 O 3 16.71 ± 0.79, total Fe 2 O 3 0.15 ± 0.08, and SiO 2 35.73 ± 0.63 wt.% ( n = 38). The occupancy of Mg at the octahedral X site refined with the neutron-diffraction data is 0.48(3), the same as that obtained by chemical analysis. The occupancies of Cr and Al refined with the X-ray-diffraction data were 0.32(1)Cr and 0. 20Al at the X site, and 0.31Cr and 0.69Al at the Y site. Bond-valence considerations support the validity of the refined occupancies and the assumption that Cr is trivalent. Accordingly, the formula is established as Ca 8.00 (Mg 1.92 Cr 1.28 Al 0.80 ) ∑4.00 (Al 5.52 Cr 2. 48 ) ∑8.00 Si 12.00 O 42.12 (OH) 13.88 . Although Cr 3+ ions occur at both the X and Y sites, the distribution coefficient [(Cr/Al) X /(Cr/Al) Y = 3.56] indicates a stronger preference of Cr for the X site than the Y site. The unit-cell parameters were refined as a 8.8193(5), b 5.9396(3), c 19.161(1) A, β 97.603(2)° and V 994.86(9) A 3 (neutron data), and a 8.8132(2), b 5.9342(1), c 19.1466(3) A, β 97.603(2)° and V 992.54(3) A 3 (X-ray data). Substitution of chromium for aluminum at the Y site increases the mean Y –O distance by expansion of the octahedra, which causes increase in the a , b , and c dimensions. However, the mean X –O distance is not correlated with mean ionic radius at the X site. Distortion parameters of the Y site tend to decrease with increasing mean Y –O distance and volume of the site. Expansion of octahedra by ionic substitutions of larger cations for Al at the Y site thus causes a gradual change of the octahedra to a highly symmetrical and regular form.
贾安四国中部桑巴川变质带绿辉岩中的铬绿帘石
DOI：
--
发表时间：
2006
期刊：
Journal of Mineralogical and Petrological Science (refereed journal) 101
影响因子：
--
作者：
Nagashima;M.;Akasaka;M.;Sakurai;T
通讯作者：
T