The sodium tungsten bronzes (Na_xWO₃) are sub-stoichiometric metal oxides with variable Na content described by x. Methods to determine the overall x of a sample are well-known, but variations of composition within a particle have not yet been explored. In this work, electron microscopy techniques are used to determine the crystallinity and chemical composition of individual Na_0.83WO₃ nanocubes. The particles are found to be single crystals, with the top and bottom faces of the nanocubes parallel to the {100} planes. Compositional homogeneity is observed within the particles other than an approximately ≈5 nm Na-depletion layer at the edge of the particle. An O-depleted layer, believed to be the result of beam damage, is observed when the beam is scanned slowly over the edge of the particle. Calculations of the plasmon responses using the boundary element method (BEM) show that this depletion layer has a minor impact on the optical properties of the large (190 nm) particle studied of this work, but is expected to have a dramatic impact for small (20 nm) particles.

钠钨青铜（Na _x WO ₃）是亚化学计量的Na含量可变的金属氧化物，用x表示。确定样品的总x的方法是众所周知的，但是尚未探索颗粒内组成的变化。在这项工作中，使用电子显微镜技术确定单个Na _0.83 WO ₃的结晶度和化学组成。纳米立方体。发现这些粒子是单晶，纳米立方体的顶面和底面平行于{100}平面。除了在颗粒边缘处约5 nm的Na耗尽层以外，在颗粒内观察到成分均一性。当在粒子的边缘上缓慢扫描光束时，会观察到O耗尽层，该光束被认为是光束损坏的结果。使用边界元方法（BEM）进行的等离激元响应计算表明，该耗尽层对这项工作研究的大颗粒（190 nm）的光学性能影响不大，但预计对小颗粒（190 nm）会产生巨大影响。 20 nm）颗粒。