Abstract Automated mineralogy instrumentation (QEMSCAN, MLA, TIMA) is routinely used for materials characterization in the mining industry. All current techniques identify minerals based on a combination of backscattered electron and chemical (energy-dispersive spectroscopy) signals read from the sample. Boundary zones, where two or more minerals are touching, yield signals that reflect a mix of the characteristics of multiple minerals and that may or may not match anything in the mineral database. These phase boundaries, varying in width, are known to cause errors in automated mineralogy analyses, but what mineral and boundary characteristics affect phase boundary width and how much error phase boundaries can cause remain poorly understood. New Monte Carlo modeling of electron-sample interactions at and near phase boundaries shows that the width of the zone of mixed signals, and hence the amount of error, depends on the grain size and texture of the sample; the densities of the minerals and the ionization potentials of their constituent elements; and the position and orientation of the boundary between the minerals, as well as various instrumental factors such as beam accelerating voltage. Error induced by phase boundaries is high when a high accelerating voltage is used to examine fine-grained samples with complex (intergrowth, exsolution) textures that involve low-density minerals with low-ionization-potential elements. Error is low when the sample is coarse-grained, lacks complex textural relationships that create boundary area, and consists of high-density minerals with high-ionization-potential elements, which have a higher electron stopping power and prevent the beam from spreading out as much. Where low- and high-density minerals are in contact at an angled boundary, the width of the boundary zone is low when the high-density mineral is on top and high when the low-density phase is on top. Calculations based on these simulations indicate that the amount of area that could fall within phase boundary zones depends strongly on grain size, shape, and width of boundary zone. Boundary phases may contribute significantly to overall analytical error for fine-grained minerals with low densities and composed of elements with low ionization potentials, but for most samples the boundary phase area is likely to be

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相边界处电子-样品相互作用的蒙特卡罗模拟及其对自动化矿物学的影响

摘要 自动化矿物学仪器（QEMSCAN、MLA、TIMA）通常用于采矿业的材料表征。所有当前的技术都基于从样品中读取的背散射电子和化学（能量色散光谱）信号的组合来识别矿物。两种或多种矿物接触的边界带产生的信号反映了多种矿物的混合特征，并且可能与矿物数据库中的任何内容相匹配，也可能不匹配。已知这些宽度不同的相界会在自动矿物学分析中导致错误，但哪些矿物和边界特征会影响相界宽度以及相界会导致多少错误仍然知之甚少。相边界处和附近电子-样品相互作用的新蒙特卡罗模型表明，混合信号区域的宽度以及由此产生的误差量取决于样品的晶粒尺寸和质地；矿物的密度及其组成元素的电离势；以及矿物之间边界的位置和方向，以及束加速电压等各种仪器因素。当使用高加速电压检查具有复杂（共生、出溶）纹理的细粒样品时，相界引起的误差很高，这些样品涉及具有低电离电位元素的低密度矿物。样本粗粒度时误差低，缺乏创建边界区域的复杂纹理关系，由具有高电离电位元素的高密度矿物质组成，具有更高的电子阻止能力并防止电子束尽可能多地扩散。当低密度和高密度矿物在倾斜边界处接触时，当高密度矿物在顶部时边界带的宽度较低，当低密度相在顶部时边界带的宽度较高。基于这些模拟的计算表明，可能落入相界区的面积很大程度上取决于晶粒尺寸、形状和边界区的宽度。对于由低电离势元素组成的低密度细粒矿物，边界相可能对整体分析误差产生重大影响，但对于大多数样品，边界相面积可能为 具有更高的电子阻止能力并防止光束扩散。当低密度和高密度矿物在倾斜边界处接触时，当高密度矿物在顶部时边界带的宽度较低，当低密度相在顶部时边界带的宽度较高。基于这些模拟的计算表明，可能落入相界区的面积很大程度上取决于晶粒尺寸、形状和边界区的宽度。对于由低电离势元素组成的低密度细粒矿物，边界相可能对整体分析误差产生重大影响，但对于大多数样品，边界相面积可能为 具有更高的电子阻止能力并防止光束扩散。当低密度和高密度矿物在倾斜边界处接触时，当高密度矿物在顶部时边界带的宽度较低，当低密度相在顶部时边界带的宽度较高。基于这些模拟的计算表明，可能落入相界区的面积很大程度上取决于晶粒尺寸、形状和边界区的宽度。对于由低电离势元素组成的低密度细粒矿物，边界相可能对整体分析误差产生重大影响，但对于大多数样品，边界相面积可能为 当高密度矿物在顶部时边界带的宽度小，当低密度相在顶部时边界带的宽度高。基于这些模拟的计算表明，可能落入相界区的面积很大程度上取决于晶粒尺寸、形状和边界区的宽度。对于由低电离势元素组成的低密度细粒矿物，边界相可能对整体分析误差产生重大影响，但对于大多数样品，边界相面积可能为 当高密度矿物在顶部时边界带的宽度小，当低密度相在顶部时边界带的宽度高。基于这些模拟的计算表明，可能落入相界区的面积很大程度上取决于晶粒尺寸、形状和边界区的宽度。对于由低电离势元素组成的低密度细粒矿物，边界相可能对整体分析误差产生重大影响，但对于大多数样品，边界相面积可能为