Synthesis and crystal chemistry of mukhinite, V-analogue of clinozoisite on the join Ca2Al3Si3O12(OH)?Ca2Al2VSi3O12(OH)
Synthesis and crystal chemistry of mukhinite, V-analogue of clinozoisite on the join Ca2Al3Si3O12(OH)?Ca2Al2VSi3O12(OH)
复制标题
Ca2Al3Si3O12(OH)?Ca2Al2VSi3O12(OH) 斜长石 V 类似物 Mukhinite 的合成和晶体化学
DOI：
10.1007/s00269-018-0988-4
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发表时间：
2018
影响因子：
1.4
通讯作者：
Kawasaki Toshisuke
中科院分区：
文献类型：
--
作者：
Nagashima Mariko;Nishio-Hamane Daisuke;Nakano Nobuhiko;Kawasaki Toshisuke
本文首次报道了在1.5GPa和800 °C条件下合成的Ca_2Al_3Si_3 O_（12）（OH）-Ca_2Al_2 V_3 + Si_3 O_（12）（OH）连接体上的钒类似斜锆石的晶体结构。研究了V3+在结构独立的八面体M1、M2和M3位上的分布，以及V3+对晶体结构的影响。所有运行产品中的Mukhinite和V3+轴承斜锆石与锆石，也共存的V-轴承相，如vanadomalayaite，goldmanite，V-氧化物，和身份不明的钙铝轴承钒酸盐。在运行20产物中结晶的Mukhinite和含V3+的斜锆石显示出在0.33和0.74 V原子/式单元（apfu）之间的组成间隙，并且V含量达到1.14 apfu。低V3+-和高V3+-斜殖子石的共存表明在1.5 GPa和800 °C下存在可磁化率间隙。两个mukhinite晶体与0.75和0.83 V3+apfu用于X射线单晶结构分析。晶胞参数：前者area= 8.8995（2），B= 5.6299（1），c= 10.1532（2）λ，β= 115.327（1）°，V = 459.81（2）λ 3，后者anda= 8.8999（1），B= 5.6357（1），c= 10.1499（1）λ，β= 115.306（1）°，后者V = 460.24（2）× 3。V ~（3+）在八面体中的位置分别为：前者M1（Al_（0.894（6）V_（0.106））M2（Al_（0.976（6）V_（0.024））M3（V_（0.621（6）Al_（0.379），后者M1（Al_（0.868（4）V_（0.132））M2（Al_（0.957（4）V_（0.043））M3（V_（0.652（2）Al_（0.348））。V ~（3+）与Fe ~（3+）、Mn ~（3+）一样，在八面体上的位置偏好为M_3> M_1> M_2。V ~（3+）和Al ~（3+）在M_1和M_3位间的晶内分配系数KD=（V ~（3+）/Al）M_1/（V ~（3+）/Al）M_3 = 0.07-0.08，大于Fe ~（3+）和Al ~（3+）的分配系数KD = 0.03-0.05，也大于Mn ~（3+）和Al ~（3+）的分配系数KD = 0.04-0.06。晶胞参数的变化与M3− Oi和M1− Oi距离的变化密切相关。
This is the first report of the crystal structure of mukhinite, V-analogue clinozoisite, on the join Ca2Al3Si3O12(OH)–Ca2Al2V3+Si3O12(OH) synthesized at 1.5 GPa and 800 °C. The study was performed to clarify the distribution of V3+among structurally independent octahedral M1, M2, and M3 sites, and the effect of V3+on the crystal structure. Mukhinite and V3+-bearing clinozoisite in all run products are associated with zoisite, and also coexist with V-bearing phases such as vanadomalayaite, goldmanite, V-oxides, and unidentified Ca–Al-bearing vanadates. Mukhinite and V3+-bearing clinozoisite crystallized in the Run 20 product show a compositional gap between 0.33 and 0.74 V atoms per formula unit (apfu), and the V content attains 1.14 apfu. The coexistence of low V3+- and high V3+-clinozoisites indicates the presence of a miscibility gap at 1.5 GPa and 800 °C. Two mukhinite crystals with 0.75 and 0.83 V3+apfu were used for X-ray single-crystal structure analysis. The unit-cell parameters area= 8.8995(2),b= 5.6299(1),c= 10.1532(2) Å,β= 115.327(1)°, andV= 459.81(2) Å3for the former, anda= 8.8999(1),b= 5.6357(1),c= 10.1499(1) Å,β= 115.306(1)°, andV= 460.24(2) Å3for the latter. The resulting V3+occupancies among the octahedral sites areM1(Al0.894(6)V0.106)M2(Al0.976(6)V0.024)M3(V0.621(6)Al0.379) for the former andM1(Al0.868(4)V0.132)M2(Al0.957(4)V0.043)M3(V0.652(2)Al0.348) for the latter. Site preference of V3+at the octahedral sites is M3 > M1 > M2 as that of Fe3+and Mn3+. The intracrystalline partition coefficient of V3+and Al3+between the M1 and M3 sites,KD= (V3+/Al)M1/(V3+/Al)M3, is 0.07–0.08, which is greater than those of Fe3+and Al3+(0.03–0.05) and of Mn3+and Al3+(0.04–0.06). Variations of the unit-cell parameters are strongly related to the variations of the M3−Oiand M1−Oidistances.