二维链间扩展的极化子动力学研究

基于扩展的SSH模型,研究了有序耦合聚合物链系统中的极化子动力学,包括极化子的形成过程及其在外场下的输运.发现,当聚合物链间的耦合较强时,注入到系统中的电子会诱发二维链间扩展的极化子态,分布在多条聚合物链上.另外,动力学模拟表明,与一维链内定域极化子相比,在相同的电场强度下二维极化子具有更大的运动速度,这与实验结果一致.     

1600 K和20 GP温压条件下的顽火辉石电导率

在温度750～1600 K和压力10～20 GPa条件下,借助于Kawai-5000多面顶砧高温高压设备,就位测量了(Mg_0.9Fe_0.1) SiO₃ 顽火辉石的电导率.实验结果显示,顽火辉石的电导率在高温区以小极化子机制为主,在低温区以质子导电为主,因为实验后的样品中有一定的水含量.另外,X射线衍射实验表明压力（20 GPa）诱发了顽火辉石向林伍德石的相变,这是我们首次在顽火辉石的电导率实验中观测到林伍德石含水相变,而且含水林伍德石的电导率与已有的实验结果相当一致.     

Experimental Study on the Electrical Conductivity of Orthopyroxene atHigh Temperature and High Pressure under Different Oxygen Fugacities

1 Introduction recognized and accepted by more and more experts engaged in experimental research at high temperature and In-situ laboratory measurement of the electricity of high pressure. This method has been regardedgeological materials at high temperature and high pressure internationally as the most advanced one for the in-situis an important approach to revealing the composition, laboratory measurement of the electric properties ofstructure and properties of materials in the deep interior…     

Color centers in topaz: comparison between neutron and gamma irradiation

Neutron- and gamma irradiation-induced paramagnetic centers in natural colorless topaz from four different Brazilian localities were studied by electron paramagnetic resonance (EPR) and optical absorption as a function of irradiation dose and thermal treatment. Gamma irradiation doses were applied up to 1,000 kGy with a dose rate of 15 kGy h⁻¹. For the neutron irradiation experiments, a neutron flux of 4 × 10¹² cm⁻² s⁻¹ was used with an integrated flux of up to 1 × 10¹⁸ cm⁻². From the experiments, it is concluded that brownish colors are induced by gamma-rays and may be associated with a single broad isotropic EPR line with g = 2.015(2). Both the EPR line and the related optical absorption band at 460 nm (2.7 eV) are lost during thermal treatments between 150 and 200°C. Fast neutrons create the paramagnetic peroxyl radicals O₂ ⁻ and the paramagnetic O⁻ hole centers. The O⁻ centers have the same thermal stability as the optical absorption band at 620 nm (2.0 eV). It is confirmed that the absorption due to the O⁻ center is responsible for the blue color in topaz. Both color centers and their absorption bands are discussed in the context of O⁻ bound small polarons.     

高温高压和控制氧逸度条件下透辉石电导率的各向异性实验研究

在1.0～4.0GPa 和1073～1373K 及控制氧分压条件下,借助于 YJ-3000t 紧装式六面顶固体高压设备和1260阻抗/增益-相位分析仪,就位测定了沿着不同晶轴方向的透辉石的电导率。氧逸度控制是由 Ni+NiO 固体缓冲剂完成的。实验结果表明:(1)在选择的频率范围,无论从复阻抗的模与频率还是从相角与频率关系上,部可以看出复阻抗对频率具有很强的依赖性;(2)随着温度升高,阻抗降低,电导率增大,Logo 与1/T 之间符合 Arrenhius 线性关系式;(3)随着压力升高,[001]方向的透辉石电导率降低,活化焓和指前因子亦随之减小,并首次获得了透辉石中主要载流子的活化能和活化体积分别为1.80±0.04eV 和0.035±0.015cm~3/mol;(4)在2.0GPa 下按照[001]、[100]、[010]的顺序,样品的电导率和指前因子降低,活化焓依次升高,高压下的透辉石电学性质存在各向异性;(5)小极化子导电机制可为透辉石在高温高压下的导电行为提供合理的解释。