Nuclear and Radiochemical Analysis

Ehmann, W. D.; Robertson, J. D.; Yates, S. W.

doi:10.1021/ac00084a011

Cited by 10 publications

(5 citation statements)

References 7 publications

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“…18a),the powder was heated in air Between 30-280°C, moisture which was absorbed during air exposure was lost, and between 280 and 800°C the following weight loss occurred Li2CO, + 2NiO + O2 -* 2LiNiO2 + co9t [16] Li2CO3 + Pt + 024 -÷ Li2PtO2 + C021 [17] Li2CO2 -+ Li20 C02t [18] The small weight loss during the 1 h dwell time at 800°C is attributed mostly to these reactions. 18a),the powder was heated in air Between 30-280°C, moisture which was absorbed during air exposure was lost, and between 280 and 800°C the following weight loss occurred Li2CO, + 2NiO + O2 -* 2LiNiO2 + co9t [16] Li2CO3 + Pt + 024 -÷ Li2PtO2 + C021 [17] Li2CO2 -+ Li20 C02t [18] The small weight loss during the 1 h dwell time at 800°C is attributed mostly to these reactions.…”

Section: Iii) the Close Structural Relationship Between Linio3 Andmentioning

confidence: 99%

“…In the first run (Fig. 18a),the powder was heated in air Between 30-280°C, moisture which was absorbed during air exposure was lost, and between 280 and 800°C the following weight loss occurred Li2CO, + 2NiO + O2 -* 2LiNiO2 + co9t [16] Li2CO3 + Pt + 024 -÷ Li2PtO2 + C021 [17] Li2CO2 -+ Li20 C02t [18] The small weight loss during the 1 h dwell time at 800°C is attributed mostly to these reactions. After cooling to room temperature, we obtained Li1 24Mn9 36Ni240O2.…”

Section: Iii) the Close Structural Relationship Between Linio3 Andmentioning

confidence: 99%

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Lithium Manganese Nickel Oxides Li x ( Mn y Ni1 − y ) 2 − x O 2 : I. Synthesis and Characterization of Thin Films and Bulk Phases

Neudecker

Zuhr

Kwak

et al. 1998

J. Electrochem. Soc.

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The series Li(Mn Ni1_ )2_O2 for x s 1.33 and 0.38 y 0.50 shows a very close relationship to its parent series LiNi202. The refineà lattice parameters for at least 0.93 x 1.26 are a linear function of the concentration ratio Li/(Mn + Ni) which in turn is proportional to the averaged valence state of the transition metals. Li(Mn9Ni1_9)202 is able to reversibly coprecipitate/reinsert Li20 and release/absorb 02. This self-regulation mechanism seems to always adjust the number of cations to an undisturbed oxygen sublattice according to the rule "cations/anions = 1," which holds true at least for temperatures up to 800°C and oxygen partial pressures above i0 atm. Samples prepared in air and under 02 did not show nucleation of Li20, not even for x> 1.0. The series Li(Mn6Ni1_6)202 where 0.38 y 0.50 crystallizes in a rhombohedral unit cell (space group R3m) for x < 1.15 and transforms into a single monoclinic phase (space group C2/c) for x> 1.25. The similarity between LiNi2_02 and Li,(Mn0Ni1_9)202 strongly suggests a rhombohedralcubic transition at x 0.6 for the latter series. Derived from the linear dependence of the X-ray density on the stoichiometric parameter x, an equation was found with which the lithium concentration of Li(Mn9Ni,_0)202 thin film phases over the entire range 0 x 1.33 can be determined accurately without extensive ion-beam analysis. XPS measurements on a film with the bulk stoichiometry Li110Mn039Ni05102 gave evidence for Mn4 and Mn3, but no indication was found for nickel valence states other than Ni2. In order to meet the above-given stoichiometry, the averaged nickel valence state had to increase with film depth. lnfroduction In recent years, LiNiO2 has been used as a cathode material in high-voltage lithium-ion and lithium batteries.1-4 Electrochemical experiments, however, showed that a slight deviation from the ideal starting stoichiometry LiNiO2 resulted in a poor cell performance caused by Ni2 defects on Li sites.5 Moreover, upon extensive lithium deintercalation wherein x in LiNi02 approaches zero and the nickel valence state comes close to its maximum of +4, nickel ions migrate from their nickel layer sites into the vacancies of the lithium layers. Such nickel migration creates severe diffusional limitations to lithium reinsertion thereby reducing cell performance. 6 These drawbacks stimulated our research on the partially substituted manganese derivatives of LiNiO2, namely, Li(Mn.4Ni1_9)202. In particular, it was felt that the introduction of Mn" "buffer ions," which easily form under typical solid-state preparation conditions such as annealing at 700°C in air; would lift the electrochemically detrimental effect Ni2-defects impose on chemically prepared LiNiO2 cathodes. That is, Mn" ions could help balance the two oxygen anions without the need of Ni2 occupying Li sites. * Electrochemical Society Active Member. The purpose of this paper is to describe the synthesis and characterization of Li(Mn0Ni10)202 in thin-film and bulk forms. Our electrochemical studies of the thin films are reporte...

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Section: Iii) the Close Structural Relationship Between Linio3 Andmentioning

confidence: 99%

Section: Iii) the Close Structural Relationship Between Linio3 Andmentioning

confidence: 99%

Lithium Manganese Nickel Oxides Li x ( Mn y Ni1 − y ) 2 − x O 2 : I. Synthesis and Characterization of Thin Films and Bulk Phases

Neudecker

Zuhr

Kwak

et al. 1998

J. Electrochem. Soc.

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“…Additional sources of recent information on utilizing NAA in selected fields, such as air pollution and environmental analysis, food, forensic science, geological and inorganic materials as well as water analysis can be found in the bi-annual reviews in Analytical Chemistry, for instance cf. Refs [34][35][36][37][38][39][40][41][42]. It follows from these reviews that NAA has been applied for determining many elements, usually trace elements, in the following fields and sample types:…”

Section: Applicationsmentioning

confidence: 99%

Concepts, Instrumentation and Techniques of Neutron Activation Analysis

Hamidatou¹,

Slamene²,

Akhal³

et al. 2013

Imaging and Radioanalytical Techniques in Interdisciplinary Research - Fundamentals and Cutting Edge Applications

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Nowadays, there are many elemental analysis methods that use chemical, physical and nuclear characteristics. However, a particular method may be favoured for a specific task, depending on the purpose. Neutron activation analysis (NAA) is very useful as sensitive analytical technique for performing both qualitative and quantitative multielemental analysis of major, minor and traces components in variety of terrestrial samples and extra-terrestrial materials. In addition, because of its accuracy and reliability, NAA is generally recognized as the "referee method" of choice when new procedures are being developed or when other methods yield results that do not agree. It is usually used as an important reference for other analysis methods. Worldwide application of NAA is so widespread it is estimated that approximately 100,000 samples undergo analysis each year. The method is based on conversion of stable atomic nuclei into radioactive nuclei by irradiation with neutrons and subsequent detection of the radiation emitted by the radioactive nuclei and its identification. The basic essentials required to carry out an analysis of samples by NAA are a source of neutrons, instrumentation suitable for detecting gamma rays, and a detailed knowledge of the reactions that occur when neutrons interact with target nuclei. Brief descriptions of the NAA method, reactor neutron sources, and gammaray detection are given below.

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“…More detailed information about the principle and application of NAA in chemical speciation can be seen in several publications. [14][15][16][17] The main advantages of the hybrid procedure are of its high sensitivity and the absence of matrix effects inherited from the conventional neutron activation analysis. The high sensitivity of analytical methods is a prerequisite to obtaining reliable results.…”

Section: Neutron Activation Analysis (Naa)mentioning

confidence: 99%