Analysis of total nitrogen and total phosphorus in soil using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy(LIBS) is used to determine the total nitrogen(TN) and total phosphorus(TP) in soil.Quantitative determinations are conducted using the line intensity of the analyte element and element concentration.Calibration models are obtained using ten samples for TN and seven samples for TP.The rest samples are used to validate the results.Strong linear correlations are obtained from the determined TN and TP concentrations.LIBS is a powerful tool for analyzing soil samples to determine nutrient elements by selecting calibration and validation samples with similar matrix composition.     

氧离子导体La1.9Y0.1Mo2O9细晶粒陶瓷的制备和电学性质研究

采用溶胶凝胶法合成的La_1.9Y_0.1Mo₂O₉纳米晶粉体, 结合微波烧结技术制备出不同晶粒度的La_1.9Y_0.1Mo₂O₉块体样品. 利用X射线衍射仪(XRD)、高分辨透射显微镜(HRTEM)、场扫描显微镜(SEM)对粉体及陶瓷块体的物相、 形貌进行了表征, 利用交流阻抗谱仪测试了样品不同温度下的电导率. 实验结果表明, 掺Y的La_1.9Y_0.1Mo₂O₉能将高温立方β 相稳定到室温; 块体样品致密均匀, 平均晶粒度范围在60 nm–4 μm之间; 致密度高的样品表现出高的电导率, 其中900 ℃烧结样品的电导率600 ℃时高达0.026 S/cm, 比固相反应法制备的La_1.9Y_0.1Mo₂O₉样品高出约1倍. 总结认为样品的致密性对电导率影响较大, 是通过影响晶界电导率来影响总电导率的, 样品的晶粒度(在60 nm–4 μm范围内)对电导率的影响还不能确定. 关键词： 氧离子导体 1.9Y_0.1Mo₂O₉')" href="#">La_1.9Y_0.1Mo₂O₉ 细晶粒陶瓷 微波烧结     

Correlation of Lithium Ionic Diffusion with Nb Concentration in Li7-xLa3Zr2-xNbxO12 Evaluated by an Internal Friction Method

Solid lithium-ion conductors Li7-xLa3Zr2-xNbxO12（x =0.25, 0.5, 1, 1.5） with cubic garnet structure are suc- cessfully prepared by a solid state reaction method, and the effects of Nb concentration on lithium ion diffusion are investigated by means of internal friction （IF） technique. A prominent relaxation-type IF peak （actually composed of two components） is observed in each Nb doped LiTLa3Zr2012 compound： with apeak PL at lower temperature and a peak PH at higher temperature. The mechanisms of the two components are suggested to be associated with two diffusion processes of lithium ions via vacancies： 48g ←→ 48g and 489 ←→ 24d. The relaxational strength of the IF peak gradually decreases, which is accompanied by the activation energy increasing from 0.45 eV to 0.64 eV with the increasing Nb doping level. The corresponding mechanism is ascribed to originate from lattice contraction as well as the lower concentration of diffusion ions induced by the substitution of Zr4＋ by Nb5＋.     

Phase Transition and Oxygen Ion Diffusion in (La1-xLnx)2Mo2O9 (Ln=Nd, Gd, x=0.05-0.25) Using Dielectric Relaxation Method

采用介电弛豫方法研究了氧离子导体(La1-xRex)2Mo2O9(Re=Nd, Gd, x=0.05-0.25)中氧离子扩散和相变行为. 观察到了两个介电损耗峰：第一个峰Pd在600 K附近，第二个峰Ph在720 K左右.Pd峰为弛豫型介电损耗峰，是由氧离子的短程扩散导致的. 随着频率增加，Ph峰基本上不随频率移动，但是峰高随着频率显著的下降.Ph峰表现出非弛豫型的本质，对应于氧离子和氧空位的分布从静态无序到动态无序的转变过程. 随着掺杂浓度的增加，Pd峰和Ph峰的峰高先是增加，在15%的掺杂量达到最高后开始降低. 与此对应，电导率也在此掺杂浓度下出现最大值.