Department of Chemistry, Missouri State University, Temple Hall 456, Springfield, MO 65897, USA.
Bruker AXS, Inc., Madison, WI 53722, USA.
Molecules. 2021 Mar 9;26(5):1494. doi: 10.3390/molecules26051494.
Interactions between well-mixed fine powders of AsO, PO, MoO, WO and NbO at different stoichiometry in quartz ampoules under vacuum at ~1000 °C in the presence of metallic molybdenum (or niobium), over several weeks, led to shiny dichroic crystalline materials being formed in cooler parts of the reaction vessel. An addition of small quantities of metals-Mo or Nb-was made with the aim of partially reducing their highly oxidized Mo(VI), W(VI) or Nb(V) species to corresponding Mo(V), W(V) and Nb(IV) centers, in order to form mixed valence solids. Sublimed crystals of four new compounds were investigated using a variety of techniques, with prime emphasis on the X-ray analysis, followed by spectroscopy (diffusion reflectance, IR, Raman and EPR), second harmonic generation (SHG), thermal analysis under N and air atmosphere, and single crystals electrical conductivity studies. The results evidenced the formation of new complex solids of previously unknown compositions and structures. Three out of four compounds crystallized in non-centrosymmetric space groups and represent layered 2D polymeric puckered structures that being stacked on each other form 3D lattices. All new solids exhibit strong second-harmonic-generation (SHG effect; based on YAG 1064 nm tests with detection of 532 nm photons), and a rare when crystals physically move in the laser beam. Single crystals' electrical conductivity of the four new synthesized compounds was measured, and the results showed their semiconductor behavior. Values of band gaps of these new solids were determined using diffusion reflectance spectroscopy in the visible region. Aspects of new solids' practical usefulness are discussed.
在真空石英安培瓶中，在 1000°C 左右，金属钼（或铌）存在下，将 AsO、PO、MoO、WO 和 NbO 的混合细粉末在不同化学计量比下进行相互作用，经过数周时间，在反应容器的较冷部分形成了有光泽的二向色晶状材料。加入少量金属钼或铌，目的是部分还原其高度氧化的 Mo(VI)、W(VI) 或 Nb(V) 物种，形成相应的 Mo(V)、W(V) 和 Nb(IV) 中心，以形成混合价固体。使用多种技术研究了四种新化合物的升华晶体，主要重点是 X 射线分析，其次是光谱学（漫反射、IR、拉曼和 EPR）、二次谐波产生（SHG）、在 N 和空气气氛下的热分析，以及单晶电导率研究。结果表明，形成了以前未知组成和结构的新复杂固体。四种化合物中有三种在非中心对称空间群中结晶，代表层状二维聚合的褶皱结构，这些结构相互堆积形成 3D 晶格。所有新的固体都表现出强烈的二次谐波产生（SHG 效应；基于 YAG 1064nm 测试，检测到 532nm 光子），并且当晶体在激光束中物理移动时会产生罕见的 。测量了四种新合成化合物的单晶电导率，结果表明它们具有半导体行为。使用可见区域的漫反射光谱法确定了这些新固体的带隙值。讨论了新固体实际用途的各个方面。
