Valence state analysis of elements by EPMA and its application

1990 ◽  
Vol 48 (2) ◽  
pp. 230-231
Author(s):  
Chen Liqing ◽  
Liu Zuqin ◽  
Zhang Wei
Keyword(s):  
Valence State ◽  
Line Intensities ◽  
Valence States ◽  
Valence Electrons ◽  
Fe And Mn ◽  
Intensity Ratios ◽  
State Analysis

Valence state analyses of Fe and Mn in oxides by EPMA have been reported in literature. In this paper, the effects of valence state on intensity ratios ILα/IKα and ILα/ILβ of Cu, Ni, Co, Fe, Mn, Cr and their oxides, and on intensity ratios ILβ2/ILα1 and ILγ1/ILα1 of Mo, Nb, Zr and their oxides were studied. It was observed that intensity ratios change with valence states in accordance with some regularities, and these effects could be utilized for analyzing the valence states of catalysts.Valence state analysis of elements by EPMA is based on the fact that changes in the states of valence electrons in the outer shells of an atom cause corresponding changes in line intensities. The M electrons of Cu, Ni, Co, Fe, Mn, Cr and the N electrons of Mo, Nb, Zr are valence electrons. Line Kα1,2 and six lines of L are produced from the transitions of K-L2,3 and L-M or L-N respectively.

A novel approach to the study of surface oxidation states and oxidation of transition metals by Auger electron spectroscopy

1980 ◽  
Vol 370 (1741) ◽  
pp. 269-280 ◽  
Keyword(s):  
Transition Metal Oxides ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Surface Oxidation ◽  
Oxidation States ◽  
Nickel Iron ◽  
Unique Probe ◽  
Novel Approach ◽  
Valence Electrons ◽  
Intensity Ratios

L 23 M 45 M 45 /L 23 M 23 M 45 ,L 23 M 45 M 45 /L 23 M 23 M 23 and L 23 M 23 M 23 Auger intensity ratios in transition metal oxides and sulphides are shown to be directly related to the number of valence electrons in the metal as well as to its oxidation state. The metal Auger intensity ratios provide a unique probe, independent of O(KLL) intensity, to study surface oxidation states of metals. These intensity ratios have been effectively employed to investigate surface oxidation of nickel, iron and copper. The oxidation studies have unravelled some interesting aspects of surface oxidation.

VALENCE STATES AND LOCAL ENVIRONMENT OF THALLIUM AND COPPER IONS IN SOME NEW HIGH Tc SUPERCONDUCTORS BY XAS

1989 ◽  
Vol 03 (07) ◽  
pp. 1085-1096 ◽  
Author(s):  
F. STUDER ◽  
R. RETOUX ◽  
C. MARTIN ◽  
C. MICHEL ◽  
B. RAVEAU ◽  
...  
Keyword(s):  
Valence State ◽  
Copper Ions ◽  
Local Environment ◽  
X Ray Diffraction ◽  
High Tc Superconductors ◽  
High Tc ◽  
X Ray ◽  
Valence States ◽  
X Ray Absorption ◽  
Thallium Ions

The valence states of cations inside four high T c thallium superconductors have been investigated by X-ray absorption spectroscopy at thallium LIII , LI and copper K-edges. The thallium ions are observed on LIII and LI edges in the Tl(III) valence state (empty 6s levels) in spite of large Tl-O distances in the (a, b) plane of the structure as deduced from X-ray diffraction. The presence of two types of Tl-O distances have been well established on XANES spectra and the F.T. of EXAFS have shown the presence of two very short Tl-O bonds (2.03 Å). The copper K-edges are characterized by the absence of Cu(I) state (3d10 line).

scholarly journals Behavior of SnO2 in the tin-bearing iron concentrate during a reduction sintering process

2017 ◽  
Vol 53 (1) ◽  
pp. 67-74 ◽  
Author(s):  
Z. Su ◽  
Y. Zhang ◽  
B. Liu ◽  
J. Chen ◽  
G. Li ◽  
...  
Keyword(s):  
Adverse Effect ◽  
Valence State ◽  
Gas Flow ◽  
Iron Ores ◽  
Gas Composition ◽  
Sintering Process ◽  
Iron Concentrate ◽  
Morphology Analysis ◽  
State Analysis

The reserve of tin-bearing iron ores is very large in China. However, they have not been utilized sufficiently so far due to the complex embedded relationship between iron- and tin-bearing minerals. In the present work, the behavior of tin in the tin-bearing iron concentrates during a reduction sintering process (RSP) were studied using XRD, SEM-EDS, chemical valence state analysis and morphology analysis. The results show that there is about 30 mass% tin deprived from the tinbearing iron concentrates by the RSP. The tin-bearing phases remained in the finished sinters exist as the form of stannic (Sn4+), stannous (Sn2+) compounds and metallic Sn (Sno). The atmosphere in the sinter bed during the RSP is theoretically suitable for the volatilization of SnO(g). However, the gas composition and temperature of the sintering gas flow are changeable, which bring about adverse effect to the deprivation of tin.

Advances in Valence State Analysis of Manganese in Mn4+-activated Red Phosphors for White LEDs

2020 ◽  
Vol 41 (10) ◽  
pp. 1195-1213
Author(s):  
Zhao-wu WANG ◽  
◽  
Hai-peng JI ◽  
Jian XU ◽  
Sha-sha YI ◽  
...  
Keyword(s):  
Valence State ◽  
White Leds ◽  
Red Phosphors ◽  
State Analysis

Fast Mapping of the Cobalt-Valence State in Ba0.5Sr0.5Co0.8Fe0.2O3-dby Electron Energy Loss Spectroscopy

2013 ◽  
Vol 19 (6) ◽  
pp. 1595-1605 ◽  
Author(s):  
Philipp Müller ◽  
Matthias Meffert ◽  
Heike Störmer ◽  
Dagmar Gerthsen
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Valence State ◽  
Hexagonal Phase ◽  
Fast Method ◽  
White Line ◽  
Valence States ◽  
Electron Energy Loss

AbstractA fast method for determination of the Co-valence state by electron energy loss spectroscopy in a transmission electron microscope is presented. We suggest the distance between the Co-L3and Co-L2white-lines as a reliable property for the determination of Co-valence states between 2+ and 3+. The determination of the Co-L2,3white-line distance can be automated and is therefore well suited for the evaluation of large data sets that are collected for line scans and mappings. Data with a low signal-to-noise due to short acquisition times can be processed by applying principal component analysis. The new technique was applied to study the Co-valence state of Ba0.5Sr0.5Co0.8Fe0.2O3-d(BSCF), which is hampered by the superposition of the Ba-M4,5white-lines on the Co-L2,3white-lines. The Co-valence state of the cubic BSCF phase was determined to be 2.2+ (±0.2) after annealing for 100 h at 650°C, compared to an increased valence state of 2.8+ (±0.2) for the hexagonal phase. These results support models that correlate the instability of the cubic BSCF phase with an increased Co-valence state at temperatures below 840°C.

scholarly journals The mechanism of reaction of ferricyanide-pretreated mixed-valence-state membrane-bound cytochrome oxidase with oxygen at 173 K

1978 ◽  
Vol 173 (3) ◽  
pp. 811-820 ◽  
Author(s):  
G M Clore ◽  
E M Chance
Keyword(s):  
Cytochrome Oxidase ◽  
Valence State ◽  
Linear Optimization ◽  
Mixed Valence ◽  
Mixed Valence State ◽  
Optical Wavelength ◽  
Valence States ◽  
Mechanism Of Reaction ◽  
Sequential Mechanism ◽  
Good Determination

1. The results of non-linear optimization studies on the mechanism of reaction of ferricyanide-pretreated mixed-valence-state cytochrome oxidase with O2 at 173 K are presented. The analysis is carried out on data obtained by means of dual-wavelength multi-channel spectroscopy at four wavelength pairs (444-463 nm, 604-630 nm, 608-630 nm and 830-940 nm) and at two O2 concentrations (360 micron and 520 micron). The only model that satisfies the triple requirement of a standard deviation within the standard error of the experimental data, a random distribution of residuals and good determination of the optimized parameters, is a three-intermediate sequential mechanism. 2. On the basis of the optimized values of the relative absorption coefficients of the intermediates at each wavelength obtained from the present paper together with data from optical wavelength scanning and e.p.r. spectroscopy obtained by low-temperature trapping studies, the possible valence states of the metal centres in each of the intermediates are discussed.

X-Ray Diffraction Study of Ordering in Two Sigma Phases

1966 ◽  
Vol 10 ◽  
pp. 213-220 ◽  
Author(s):  
R. W. Spor ◽  
H. Claus ◽  
Paul A. Beck
Keyword(s):  
Scintillation Counter ◽  
Pulse Height ◽  
X Ray Diffraction ◽  
Measured Intensity ◽  
Atomic Size ◽  
X Ray ◽  
Line Intensities ◽  
Ordering Schemes ◽  
Intensity Ratios ◽  
Pattern Line

AbstractX-ray powder pattern line intensities were measured for the (Cr, Re)σ and (Re, Fe)σ phases by a step-scanning diffractometer, using CrKα radiation, scintillation counter, and a pulse height analyzer. The measured intensity ratios for all available pairs of adjacent lines were compared by means of a computer with the corresponding calculated intensity ratios based on approximately 1800 different ordering schemes for each alloy. The results showed ordering in both alloys, and indicated that the ordering was based on atomic size. These results are different from those obtained previously by Kasper and Waterstrat (no ordering), and by Ageyev et al. [In (Cr, Re)σ the Cr atoms are preferentially in large coordination number positions.]

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