摘要
安康矿是在陕西省安康石梯重晶石矿床中发现的一种新矿物。分子式近于Ba_(1·2)(Ti_(5·3)V_(2.8))_(8.1)O_(16),沿C轴具一维无公度调制结构,调制波向量为q=1/2.30C。安康矿的平均结构与锰钡矿是等结构。空间群为14/m,a=10.139(4);b=2.961(2),Z=1。平均结构的强度数据收集是在cAD-4衍射仪上进行的。R=0.039(535个独立的衍射点)。安康矿的超晶胞是将其亚晶胞加大14倍而获得的,空间群P4/m,a=10.126(4),c=41.41(2),Z=14。用RIGAKU的RASA-ⅡS型衍射仪收集了8696个独立的衍射点,其中包括主衍射点及卫星衍射点。对于2353个可观察点经结构修正后R因子为0.2157。在四方柱孔道中测得了Ba原子的占位及位移。测定表明安康矿属占位调制及位移调制的复合型无公度调制,而且沿c轴方向为方波调制。
Ankangite is a new mineral discovered in the Shiti barite deposit, Ankang County, Shaanxi Province, with approximate formula Ba_(1.2)(Ti_(5.3)V_(2.8))_(8.1)O_(16). One dimensional incommensurate modulated structure is found along its c-axis, and the wave vector is q=1/2.30 c~*.Ankangite (its average strUcture)is isostructural with hollandite. Space group I4/m, a=10.139(4); b=2.961 (2) , Z=1. The intensity data of the average structure were obtained on a CAD -4 diffractometer, and R=0.039 (535 independent reflections). Its Supercell is 14 times as large as its subcell. Space group P4/m, a=10.126(4), c=41.41 (2), Z=14. 8696 independent reflections, including main and satellite reflections, were collected by RASA-ⅡS type diffractometer (RIGAKU), and R=0.2157 (2353 observed reflections). The vacancies and displacement of Ba atoms were determined in square-prismatic tunnels. The determination indicates that the incommensurate modulation of ankangite is a combination of occupancy modulation and displacive modulation, and is a square wave modulation along c-axis.
出处
《岩石矿物学杂志》
CAS
CSCD
1991年第3期233-245,T001,共14页
Acta Petrologica et Mineralogica
基金
国家自然科学基金
关键词
安康矿
晶体结构
柱红石类矿物
Ankangite
crystal structure determination
one dimensional incommensurate modulation
occupancy modulation
displacive modulation
