The magnetic phase diagram of the solid solutions U(Rh1−xRux)2Si2 has been studied by resistivity and susceptibility measurements and neutron diffraction on powder and single crystals. In the range 0 < x < 0.6 an antiferromagnetic structure (k = [001], m ‖ c) is observed. The Néel temperature first increases from TN = 137 K (x = 0) upto TN = 174 K (x = 0.375) and then decreases down to TN = 101 K (x = 0.6). The ordered U magnetic moment keeps a constant value of about 2μB//U. In between x = 0.65and x = 0.65 the Néel temperature jumps from 101 K (x = 0.6) to 44 K (x = 0.65) and the magnetic ordering changes towards a commensurate structure of wave vector [1212]. For larger x, the ordering temperature and the ordered moment decrease and vanish at about x = 0.92. Above this concentration only short-range magnetic correlations centered around [1212] are observed before they reach the peculiar behaviour of URu2Si2.

ChemInformVolume 21, Issue 9 Reviews ChemInform Abstract: Neutron Scattering Studies of Neptunium and Plutonium Compounds P. BURLET, P. BURLET DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorS. QUEZEL, S. QUEZEL DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorJ. ROSSAT-MIGNOD, J. ROSSAT-MIGNOD DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorJ. C. SPIRLET, J. C. SPIRLET DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorJ. REBIZANT, J. REBIZANT DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorO. VOGT, O. VOGT DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this author P. BURLET, P. BURLET DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorS. QUEZEL, S. QUEZEL DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorJ. ROSSAT-MIGNOD, J. ROSSAT-MIGNOD DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorJ. C. SPIRLET, J. C. SPIRLET DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorJ. REBIZANT, J. REBIZANT DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorO. VOGT, O. VOGT DRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this author First published: February 27, 1990 https://doi.org/10.1002/chin.199009357Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue9February 27, 1990 RelatedInformation

ChemInformVolume 21, Issue 6 Reviews ChemInform Abstract: Magnetic and Electronic Properties of Transuranium Compounds J. ROSSAT-MIGNOD, J. ROSSAT-MIGNOD IRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorP. BURLET, P. BURLET IRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorJ. M. FOURNIER, J. M. FOURNIER IRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorE. PLESKA, E. PLESKA IRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorS. QUEZEL, S. QUEZEL IRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this author J. ROSSAT-MIGNOD, J. ROSSAT-MIGNOD IRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorP. BURLET, P. BURLET IRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorJ. M. FOURNIER, J. M. FOURNIER IRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorE. PLESKA, E. PLESKA IRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this authorS. QUEZEL, S. QUEZEL IRF, Cent. Etud. Nucl., 38041 Grenoble, Fr.Search for more papers by this author First published: February 6, 1990 https://doi.org/10.1002/chin.199006327Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue6February 6, 1990 RelatedInformation

New syntheses of well characterized samples of the neptunium oxychalcogenides NpOZ (Z = S, Se) are described. Both compounds are tetragonal with the PbFCl-type crystal structure. Magnetic susceptibility, Mössbauer spectroscopy and neutron diffraction measurements have been carried out on polycrystalline samples. Both compounds undergo antiferromagnetic ordering below 4.2 K for NpOS and 11 K for NpOSe. The ordered moment values are 0.82 and 1.64μB for NpOS and NpOSe, respectively. Both compounds seem to be ionic with a valency 4+ on the Np atoms. The magnetic moments are aligned along the c-axis with the (+ - + -) sequence in NpOSe. Based on crystal field model and molecular field approximation, tentative interpretations are given for the magnetic properties of NpOS and NpOSe.

NpRu2Si2 has been recently synthesized and very small single crystals have been isolated (0.1 mm3). We report measurements of magnetization, electrical resistivity, neutron diffraction and Mössbauer effect performed on this intermetallic compound which orders magnetically below Tn = 28 K.

The crystal structure of EuMo6S8 has been determined from neutron diffraction in the high temperature rhombohedral phase (T > 110 K) and the low temperature triclinic phase (T < 110 K). Below the first-order transition at TN = 0.3 K the magnetic ordering corresponds to a (+ + - -) sequence of ferromagnetic (102) planes. The low temperature moment value is only m0 = 4.6 μB/Eu, much smaller than the Eu2+ free ion value (7 μB.

The physics of uranium and transuranium materials has become very attractive during the last few years and will continue to develop in the next decade. Main results obtained on Np and Pu pnictides and chalcogenides will be summarized.

The neutron scattering studies of the Np and Pu monopnictides are reviewed. The results of single-crystal measurements are emphasized. Measurements on a single crystal of NpRu2Si2 are summarized.

NpSb has been studied by Mössbauer spectroscopy (237Np and 121Sb resonances) and by neutron diffraction using single crystals. Np3+ magnetic moments order antiferromagnetically below TN = 200 K in a triple-k type I structure. A strong mixing of 5f electrons with anion p states can be deduced from results of 121Sb resonance. This mixing is certainty at the origin of the interaction mechanism responsible of the coupling between the Fourier components leading to the triple-k multiaxial magnetic structure.

CeRu2Si2 is a moderate heavy fermion (HF) system which exhibits neither magnetic nor superconducting ordering. The substitution of Ce by La suppresses progressively the HF character. CexLa1−xRu2Si2 with x = 0.08, 0.10, 0.13 and 0.20, have been investigated by elastic neutron scattering. They all order in structure of wave vector ik = (0.309, 0, 0). The magnetic moment and the transition temperature (m0 ⋍ 1.2μB and Tn ⋍ 5.8 K for x = 0.20) decrease continuously with x.

The magnetic properties of the Ce(Rh1−xRux)2Si2 solid solutions have been investigated. The antiferromagnetic structure of CeRh2Si2 remains up to x = 0.40 but the ordering temperature and the magnetic moment are strongly depressed. For x = 0.40 and 0.50 a heavy fermion behaviour is found (γ≈600 mJ/molK2) with a heavier mass for quasiparticles than in pure CeRu2Si2.

The crystal structure and some physical properties were studied on single crystals of CeMo6S8, grown by two alternative methods. The electrical resistivity reveals a Kondo behaviour together with a sharp decrease at TN = 2.6 K indicative of a magnetic transition. Crystal field splittings dominate the magnetic behaviour at both high (Δ > 1000 K) and low (two nearly degenerated doublets) temperatures, as suggested by susceptibility and magnetization measurements performed as a function of the crystal orientation. Neutron scattering experiments were also carried out on powder samples. No superlattice magnetic peak has been detected, neither inelastic peak in the whole energy range of 1–100 meV.

The magnetic phase diagram (H,T) of NpAs has been studied, by neutron diffraction, using a single crystal sample and a magnetic field applied along a [110] direction. At high temperatures incommensurate, (4+,4-) and ferromagnetic orderings are observed with Np moments along [100]. At low temperatures the triple-k type I structure transforms in high field in ferrimagnetic phases characterized by one antiferromagnetic component of type I perpendicular to H and one ferromagnetic component first aligned along [100] and then rotating toward the [110] field direction.

The hexagonal compound CeGa2 has been studied by magnetic measurements, neutron diffraction and inelastic neutron scattering experiments using polycrystalline and single crystal samples. The sine wave modulated structure observed at TN = 9.5 K down to 2 K shows that CeGa2 is a new Kondo lattice in which anisotropic exchange interactions are important.

From neutron scattering experiments, using a HoMo6S8 single crystal and measuring simultaneously the resistivity, we have established: 1.i) Below Tm1=0.75 K, the first order magnetic transition at Tm2=0.70 K, between the long range transverse sine wave modulated ordering (λ=570 Å) and the transverse antiphase modulated phase (λ=1700 Å), is distinct from the second order superconducting transition Tc2=0.685 K at which the zero resistance disappears. Actually this transition occurs when Ho3+ moments reach a value yielding a critical magnetic induction Bc2=3170 G.2.ii) Below Tc2, HoMo6S8 does not reach a normal state but a modulated superconducting state which remains down to T=0 with superconducting lamella, centered on magnetic domain walls, of thickness decreasing down to about ξ ≅200 Å.3.iii) The low temperature induced superconductivity corresponds to a true phase with bulk superconductivity which is realized because of the existence of a large demagnetizing field.4.iv) A preliminary (H, T) magnetic phase diagram.

The magnetic ordering in PuBi has been studied by neutron diffraction. In zero applied magnetic field PuBi orders at any temperature below TN = 58 K in a long period commensurate phase of wavevector k = [0,0,3/13] corresponding to a sequence 〈425〉 of ferromagnetic (001) planes. This phase is independent of the magnetic field up to large critical field where a paramagnetic state is induced. The magnetic phase diagram of PuBi is presented.

A single crystal of NpAs has been studied by neutron diffraction. In vero applied magnetic field NpAs orders at TN = 173 K with an incommensurate phase characterived by a value k = 0.232 ± 0.003 of the wavevector k = [00k] at TN, varying to k = 0.236 ± 0.003 at T ≈ 155 K. At TIC = 154 K a first-order locking transition occurs to the commensurate (4+, 4−) phase with k ≈ 14. At T0 = 138 K another first-order transition leads to the type-I phase with k = 1, persisting down to low temperatures. From measurements in a magnetic field applied along the [11&#x0304;0] direction we find that the incommensurate and (4+, 4−) phases have a collinear, single-k structure while the type-I phase has a triple-k structure. These results are compatible with a tetragonal distortion of the cubic structure at TN and a return to a cubic symmetry at T0. Preliminary results on the magnetic field behaviour are also reported.