共查询到20条相似文献,搜索用时 125 毫秒
1.
使用X射线荧光光谱仪,采用人工合成标样,设计合成了一套标准样品,采用数学校正法中的经验系数法校正元素间的互相干扰,样品不经任何处理,粉末直接压片,经验系数法校正基体效应,建立了分析测定增产丙烯助剂中磷和铁含量的方法。讨论了样品制作方法,合适的测量条件,探讨了试样中元素间的相互影响。实验结果表明,该方法重现性好,准确度和精密度较高,测定磷和铁的相对标准偏差为:0.34%和0.59%;测定范围磷为0.01%~2.5%,铁为0.01%~2.5%。分析结果与化学法、等离子发射光谱法测定结果吻合。该方法快速、简便,样品处理简单,可以不分解;分析速度远快于其他分析方法,结果准确,单次测量一个样品只需要5 min,适用范围广,满足了科研和工业生产的需要。 相似文献
2.
3.
4.
流动注射荧光法测定磷和砷 总被引:2,自引:0,他引:2
宋功武 《光谱学与光谱分析》1999,19(3):466-467
本文用流动注射荧光法研究了磷(砷)钼杂多酸与罗丹明6G的荧光猝灭反应,利用此反应测定了痕量磷和砷,磷和砷的线性范围分别为0~80和0~100μg/L,检测限分别为0.343和0.301μg/L。应用本法对铜合金中痕量磷和砷测定,取得满意结果 相似文献
5.
为了提高土壤中有效磷的检测效率和方法的稳定性,研究了现代仪器分析方法-连续流动法测定土壤中有效磷的含量,对连续流动法与农业部标准方法NY/T 148-1990《石灰性土壤有效磷测定方法》、NY/T 1121.7-2006《酸性土壤有效磷的测定》的测定结果进行配对两处理t检验,结果表明:连续流动法与标准方法检测的结果不存在系统误差,样品测定的相对标准偏差均小于10%,连续流动法测定值的相对标准偏差较标准方法略小.同时,用连续流动法对土壤标准样品GBW 07413-GBW 07414(碱法)、GBW07416-GBW 07417(酸法)进行有效磷的测定,测定值与标准值相吻合. 相似文献
6.
流动注射—罗丹明6G荧光淬灭测定痕量磷 总被引:5,自引:0,他引:5
宋功武 《光谱学与光谱分析》1991,11(3):59-61,19
本文用流动注射方法研究了磷钼杂多酸与罗丹明6G的荧光淬灭反应,利用此反应测定了痕量磷,磷量的线性范围在0-80ppb,检出限0.343ppb,分析速度可达60样/小时,本法应用于铜合金、钢样和锡矿中痕量磷的测定,取得满意结果。 相似文献
7.
ICP-AES法测定水中微量磷 总被引:16,自引:1,他引:15
用ICP-AES法测定水中磷,并确定了最佳测定条件,检出限为0.02μg.mL^-1,回收率为96.5%-102.1%,RSD为1.65%-2.83%。该法准确、快速、简便,应用于水中磷的测定,结果令人满意。 相似文献
8.
9.
原子吸收法测定有机化合物中的磷和硫 总被引:4,自引:1,他引:3
共振线处于远紫外区的磷和硫元素,不能用一般的原子吸收法直接进行测定。我们在Christian和Feldman及El-Shaarawy提出的间接测定正磷酸根、硫酸根的原子吸收法的基础上进行了改进,结合采用W.Schniger氧瓶燃烧方法破坏有机试样,使有机磷和硫化合物分别转化成磷酸根和硫酸根。对若干有机磷和硫测定与容量法结果相符。磷和硫分析绝对误差为±0.3%。当磷和硫共存时不宜直接使用本法。 相似文献
10.
多波长线性回归分光光度法同时测定磷和硅 总被引:1,自引:0,他引:1
以钼酸铵-Sb^3+-抗坏血酸为显色体系,详细考察了磷、硅的锑钼蓝杂多酸络合物的最佳形式条件,据此建立了多波长线顺归分光光度法同时测定磷、硅的新方法。该方法操作简便、快速、对多种环境水样中痕量磷、硅测定的相对标准偏差小于5%。测定结果与利用光度法分别测定的结果相吻合,相对误差小于10%。 相似文献
11.
12.
G. M. Zeer E. G. Zelenkova V. I. Temnykh A. M. Tokmin A. A. Shubin Yu. P. Koroleva A. A. Mikheev 《Technical Physics》2018,63(2):200-205
The microstructure of the transition zone and powder spacer, the concentration distribution of chemical elements over the width of the diffusion-bonded joint, and microhardness of 45 steel–compacted Ni powder spacer–45 steel layered composites formed by diffusion bonding have been investigated. It has been shown that the relative spacer thickness χ < 0.06 is optimal for obtaining a high-quality joint has been formed under a compacting pressure of 500 MPa. The solid-state diffusion bonding is accompanied by sintering the nickel powder spacer and the formation of the transition zone between the spacer and steel. The transition zone consists of solid solution of nickel in the α-Fe phase and ordered solid solution of iron in nickel (FeNi3). 相似文献
13.
为研究在不同初始条件(初始相对密度、摩擦因子)下对粉末连杆锻造致密过程的影响,运用塑性变形有限元软件DEFORM-3D对粉末连杆锻造过程进行了计算机模拟研究;研究结果表明,不同初始条件对粉末连杆锻造成形致密过程具有重要影响:(1)连杆锻造过程受到的等效应力集中在杆身部位,连杆两头的等效应力相对较小,说明其锻造过程各处所受等效应力不均匀,成形密度也不均匀;(2)初始相对密度较小的预锻坯锻造结束时,连杆大头处的材料不能达到致密,初始相对密度大的预成形坯,终锻致密效果好;(3)摩擦因数越大,连杆表面的材料流动阻力就越大,连杆大小两头就越难达到致密,说明摩擦因子对连杆相对密度分布均匀性有较大影响;通过对粉末连杆锻造致密过程影响的研究,为粉末连杆预锻坯和模具的优化设计及粉末锻造连杆的成形规律提供一定理论依据。 相似文献
14.
本文研究了压力对CrO2样品低温磁输运性质的影响.样品的X射线衍射结果表明(110)峰的相对强度随压力的增加而增大,说明压力对CrO2针状纳米颗粒有取向的作用.低温时CrO2样品的电阻和磁阻均随压力的增加而减少.实验结果表明,低温下样品的电导呈现出典型的晶粒间隧穿特征,其Δ值随着压力和磁场的增加而减小,并且Δ随磁场的变化幅度与成型压力有关,成型压力越高,Δ随磁场的变化越小.这些变化可以归因为压力对晶粒间隧穿势垒的调制.
关键词:
磁阻
压力
隧穿
势垒厚度 相似文献
15.
E. Govea-Alcaide I. García-Fornaris P. Muné R. F. Jardim 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(4):373-378
Measurements of the electrical resistivity as a function
of temperature, ρ(T), for different values of applied
magnetic field, Ba (0 ≤ Ba ≤ 50 mT), were performed in
polycrystalline samples of Bi1.65Pb0.35Sr2Ca2
Cu3O10+δ subjected to different uniaxial compacting
pressure (UCP). We have found appreciable differences in the grain
orientation between samples by using X-ray diffractometry. From
the X-ray diffraction patterns performed, in powder and pellet
samples, we have estimated the Lotgering factor along the (00l)
direction, F(00l). The results indicate that F(00l)
increases ~23% with increasing UCP suggesting that grains
of these samples are preferentially aligned along the c-axis,
which is parallel to the compacting direction. The resistive
transition of the samples have been interpreted in terms of the
thermally activated flux-creep model. In addition, the effective
intergranular pinning energy, U0, have been determined for
different applied magnetic field. The magnetic field dependence of
U0, for Ba > 8 mT, was found to follow a H- α
dependence with α = 0.5 for all samples. The analysis of the
experimental data strongly suggested that increasing UCP results
in appreciable changes in both the grain alignment and the grain
connectivity of the samples. We have successfully interpreted the
data by considering the existence of three different
superconducting levels within the samples: the superconducting
grains, the weak-links, and the superconducting clusters. 相似文献
16.
《Physics letters. A》2005,342(4):351-356
Nanocrystalline silver samples compacted under different pressures have been studied by X-ray diffraction and ultraviolet–visible reflectance spectroscopy. It is shown that the reflectance spectra exhibit an intense band at 315 nm, three weak bands at about 240, 380 and 490 nm, and a long tail at the long-wavelength side. Their origins are given. With increasing the compacting pressure, an opposite peak-shift effect of the surface plasmon resonance (SPR) was observed. It is concluded that the collaborating effects of particle aggregate and the unit-cell contraction both induced by the compacting pressure can explain these variations. 相似文献
17.
The diffuse reflectance spectrum of cupric oxide (GuO) powder in the region 300–1000 mμ. has already been studied1,2. In the present communication, the diffuse reflectance spectra of both pure and diluted cupric oxide powder samples have been reported. In the present work, the region of investigation has also been extended down to 200 mμ. 相似文献
18.
粉末冶金高温合金中元素偏析以及粉末原始颗粒边界是影响材料性能的重要因素,由于其颗粒粒径通常为几十微米,宏观的成分分布分析方法无法实现粉末原始颗粒边界处成分分布的精细表征。微束X射线荧光光谱(μ-XRF)是近年来发展起来的无损微区成分分布分析技术,可实现材料较大范围内元素快速、高分辨分布分析,目前在地质、考古、生物等领域有了较多的应用,但在复杂块状金属成分定量分布表征方面还存在一定困难,在粉末冶金工业领域还未见有应用报道。该试验研究了高温合金中各元素的荧光光谱行为,通过类型匹配的高温合金块状标准样品对元素定量模型进行了校正,建立了基于μ-XRF的高温合金成分定量分布分析方法,满足了粉末冶金工业对于较大范围内粉末边界成分分布精细定量表征的需求。该实验以经高纯钴合金化处理的放电等离子体烧结(SPS)粉末高温合金样品为研究对象,对经不同球磨时间混合处理后的粉末烧结样品中的Ni,Co,Cr,Mo,W,Ta,Ti和Al进行了定量统计分布分析,探讨了不同球磨时间对烧结样品成分分布的影响规律;发现样品中存在大量原始颗粒边界,且成分分布较不均匀,颗粒中心处仍然为原始高温合金颗粒成分,经球磨混合加入的纯Co粉颗粒仅存在于高温合金颗粒的外层,导致颗粒边缘Co含量明显高于颗粒中心。当球磨时间较短时,原始颗粒边界处存在很多Co富集区,当球磨时间增加到24 h时,由于在机械混粉过程中超细钴粉与高温合金的合金化,使烧结样品成分分布均匀性有了较大改善,原始颗粒边界处Co的含量显著下降,而其他元素的含量有所增加,说明球磨时间的延长,样品中各元素发生了明显的扩散,这将有助于元素偏析的改善,据此,该粉末冶金高温合金的制备工艺将得以改进。该法亦可应用于其他各种粉末冶金工业产品的成分定量分布表征,可为粉末冶金工艺优化、产品质量的改进提供数据支撑。 相似文献
19.
Nanocrystalline solids, formed by compacting fine powders, have been proclaimed to possess a new structure. Specific characteristics have been reported from Mössbauer studies, and these appear to confirm and reinforce a model of crystalline cores isolated by disordered, low-density grain boundaries. In measurements of three compacted samples, we were unable to reproduce the characteristics expected. Reasons are suggested as to why the results differ between similarly-prepared samples. It is pertinent to enquire whether any of the previously reported Mössbauer characteristics of fine-particle compacts require a new structural model, or whether all the results can be simply understood in terms of particle agglomerates. Reference to the literature reveals that there is no distinction. 相似文献
20.
H. Palancher S. Bos J. F. Bérar I. Margiolaki J. L. Hodeau 《The European physical journal. Special topics》2012,208(1):275-289
X-ray resonant diffraction can be applied in structural chemistry studies on powder samples. It enables an important limitation of powder diffraction to be overcome. This limitation is related to the low ability of powder diffraction to differentiate elements with close atomic numbers when they occupy the same or close crystallographic sites (mixed occupancy case) and also to discriminate cations with different valence states in different sites. However the resonant effect usually has a second order influence on the measured intensity. As a consequence, the efficiency of this method directly implies the need for excellent quality data collection and has generally been better assessed on elements present in single phase powder samples. In recent years, instrumental developments have been made in synchrotron radiation facilities which allow easier use of resonant powder diffraction for site-specific contrast and valence i.e. oxidation state analyses. Moreover, resonant contrast diffraction tools also have been proposed for better visualization of the anomalous effect both in direct and reciprocal space by using differences between electron density maps or diffraction patterns. Finally the potentialities of this technique for de novo structure solution on macromolecular systems are mentioned. 相似文献