PITSI: The neutron powder diffractometer for transition in structure investigations at the SAFARI-1 research reactor

Venter, А.M.; Heerden, Phillipus R. van; Marais, Deon; Raaths, Johannes C.; Sentsho, Zeldah N.

doi:10.1016/j.physb.2017.12.017

Cited by 3 publications

(2 citation statements)

References 6 publications

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“…PND analysis was performed at the SAFARI-1 research reactor at the South African Nuclear Energy Corporation SOC Limited (NECSA). The high-performance neutron diffraction instrument, Powder Instrument for Transition in Structure Investigations (PITSI), was used to obtain data at room temperature using a wavelength of 1.08 Å and a 4 position-sample changer that continuously rotated the samples. The diffraction patterns were measured by 17° step scans of the area detector bank to cover 10–115° in 2θ.…”

Section: Methodsmentioning

confidence: 99%

Defect-Engineered β-MnO_2−δ Precursors Control the Structure–Property Relationships in High-Voltage Spinel LiMn_1.5Ni_0.5O_4−δ

et al. 2021

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This study examines the role of defects in structure–property relationships in spinel LiMn1.5Ni0.5O4 (LMNO) cathode materials, especially in terms of Mn3+ content, degree of disorder, and impurity phase, without the use of the traditional high-temperature annealing (≥700 °C used for making disordered LMNO). Two different phases of LMNO (i.e., highly P4332-ordered and highly Fd3̅m-disordered) have been prepared from two different β-MnO2−δ precursors obtained from an argon-rich atmosphere (β-MnO2−δ (Ar)) and a hydrogen-rich atmosphere [β-MnO2−δ (H2)]. The LMNO samples and their corresponding β-MnO2−δ precursors are thoroughly characterized using different techniques including high-resolution transmission electron microscopy, field-emission scanning electron microscopy, Raman spectroscopy, powder neutron diffraction, X-ray photoelectron spectroscopy, synchrotron X-ray diffraction, X-ray absorption near-edge spectroscopy, and electrochemistry. LMNO from β-MnO2−δ (H2) exhibits higher defects (oxygen vacancy content) than the one from the β-MnO2−δ (Ar). For the first time, defective β-MnO2−δ has been adopted as precursors for LMNO cathode materials with controlled oxygen vacancy, disordered phase, Mn3+ content, and impurity contents without the need for conventional methods of doping with metal ions, high synthetic temperature, use of organic compounds, postannealing, microwave, or modification of the temperature-cooling profiles. The results show that the oxygen vacancy changes concurrently with the degree of disorder and Mn3+ content, and the best electrochemical performance is only obtained at 850 °C for LMNO-(Ar). The findings in this work present unique opportunities that allow the use of β-MnO2−δ as viable precursors for manipulating the structure–property relationships in LMNO spinel materials for potential development of high-performance high-voltage lithium-ion batteries.

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Section: Methodsmentioning

confidence: 99%

Defect-Engineered β-MnO_2−δ Precursors Control the Structure–Property Relationships in High-Voltage Spinel LiMn_1.5Ni_0.5O_4−δ

et al. 2021

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“…In addition to the production of radio isotopes, SAFARI-1 offers various irradiation services, neutron activation analysis, as well as hosts a number of neutron beam-line instruments [5]. The Powder Instrument for Transition in Structure Investigations (PITSI) [6] was commissioned in mid-2014 and has since provided the South African research community with a unique capability to perform temperature dependent angular dispersive neutron powder diffraction studies. It supports both low and high temperature sample environments to facilitate in-situ parametric studies of crystallographic and magnetic phenomena covering the temperature range 1.5 to 1800 K. Its flexibility in the choice of the monochromator reflections, focus conditions and take-off angles allow selection of instrumental characteristics that suit investigation over a wide range of scientific problems.…”

Section: Pitsi At Safari-1mentioning

confidence: 99%

Expansion of the detector bank of the Necsa neutron powder diffractometer

Marais

Heerden

Raaths

et al. 2018

JNR

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The neutron detector of Necsa's "Powder Instrument for Transition in Structure Investigations" (PITSI) diffractometer is a pseudo area configuration that has an active area of ∼ 610 × 375 mm 2 that is established by 15 vertically stacked 3 He gas-filled linear position sensitive tube detectors. In its standard geometry the sample-to-detector distance is 1.6 m that gives a detector sustention angle of 2θ = 21 •. A full diffraction pattern over the range 10 • 2θ 115 • is covered in six discrete steps. This process may be very time consuming for weak scattering materials. To improve the instrument performance, the active area of the detector bank is being increased to 48 tubes comprising three banks each with 16 tubes separated by a dead-space of 18.5°at 1.6 m. This configuration requires a step-scan of only 2 positions to cover the complete 2θ range of interest, effectively increasing the instrument acquisition speed by a factor greater than 3. As an added flexibility the overall data acquisition time can be further reduced by decreasing the sample to detector distance to 1.2 m that increases the intensity per pixel at the expense of the instrument's angular resolution. In this report the conversion of the current USB-communication based system to an Ethernet based system to reduce the hardware footprint and complexity, as well as the amount of cabling needed is reported. The optimisation of the operating parameters of the new detector electronics is also discussed.

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Structure and magnetic phase transitions in (Ni1−Co )Cr2O4 spinel nanoparticles

Mohanty

Venter

Sheppard

et al. 2020

Journal of Magnetism and Magnetic Materials

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PITSI: The neutron powder diffractometer for transition in structure investigations at the SAFARI-1 research reactor

Cited by 3 publications

References 6 publications

Defect-Engineered β-MnO_2−δ Precursors Control the Structure–Property Relationships in High-Voltage Spinel LiMn_1.5Ni_0.5O_4−δ

Defect-Engineered β-MnO_2−δ Precursors Control the Structure–Property Relationships in High-Voltage Spinel LiMn_1.5Ni_0.5O_4−δ

Expansion of the detector bank of the Necsa neutron powder diffractometer

Structure and magnetic phase transitions in (Ni1−Co )Cr2O4 spinel nanoparticles

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PITSI: The neutron powder diffractometer for transition in structure investigations at the SAFARI-1 research reactor

Cited by 3 publications

References 6 publications

Defect-Engineered β-MnO2−δ Precursors Control the Structure–Property Relationships in High-Voltage Spinel LiMn1.5Ni0.5O4−δ

Defect-Engineered β-MnO2−δ Precursors Control the Structure–Property Relationships in High-Voltage Spinel LiMn1.5Ni0.5O4−δ

Expansion of the detector bank of the Necsa neutron powder diffractometer

Structure and magnetic phase transitions in (Ni1−Co )Cr2O4 spinel nanoparticles

Contact Info

Product

Resources

About

Defect-Engineered β-MnO_2−δ Precursors Control the Structure–Property Relationships in High-Voltage Spinel LiMn_1.5Ni_0.5O_4−δ

Defect-Engineered β-MnO_2−δ Precursors Control the Structure–Property Relationships in High-Voltage Spinel LiMn_1.5Ni_0.5O_4−δ