Print Email Facebook Twitter A New Look at the Structural and Magnetic Properties of Potassium Neptunate K2NpO4 Combining XRD, XANES Spectroscopy, and Low-Temperature Heat Capacity Title A New Look at the Structural and Magnetic Properties of Potassium Neptunate K2NpO4 Combining XRD, XANES Spectroscopy, and Low-Temperature Heat Capacity Author Smith, A.L. (TU Delft RST/Reactor Physics and Nuclear Materials) Colineau, Eric (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe) Griveau, Jean Christophe (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe) Popa, Karin (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe) Kauric, Guilhem (ENSCP) Martin, Philippe M. (CEA Marcoule) Scheinost, Andreas C. (Helmholtz Zentrum Dresden Rossendorf) Cheetham, Anthony K. (University of Cambridge) Konings, Rudy J.M. (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe) Date 2017-05-15 Abstract The physicochemical properties of the potassium neptunate K2NpO4 have been investigated in this work using X-ray diffraction, X-ray absorption near edge structure (XANES) spectroscopy at the Np-L3 edge, and low-temperature heat capacity measurements. A Rietveld refinement of the crystal structure is reported for the first time. The Np(VI) valence state has been confirmed by the XANES data, and the absorption edge threshold of the XANES spectrum has been correlated to the Mössbauer isomer shift value reported in the literature. The standard entropy and heat capacity of K2NpO4 have been derived at 298.15 K from the low-temperature heat capacity data. The latter suggest the existence of a magnetic ordering transition around 25.9 K, most probably of the ferromagnetic type. To reference this document use: http://resolver.tudelft.nl/uuid:f63c26b0-e483-418a-972a-ccb7ae1f9b2c DOI https://doi.org/10.1021/acs.inorgchem.7b00462 ISSN 0020-1669 Source Inorganic Chemistry, 56 (10), 5839-5850 Part of collection Institutional Repository Document type journal article Rights © 2017 A.L. Smith, Eric Colineau, Jean Christophe Griveau, Karin Popa, Guilhem Kauric, Philippe M. Martin, Andreas C. Scheinost, Anthony K. Cheetham, Rudy J.M. Konings Files PDF acs.inorgchem.7b00462.pdf 1.8 MB Close viewer /islandora/object/uuid:f63c26b0-e483-418a-972a-ccb7ae1f9b2c/datastream/OBJ/view