At 320 K, the crystal structure of CeRuSn is commensurate with the related CeCoAl-type of structure by the doubling of the c lattice parameter. However, with lowering the temperature it becomes ...incommensurate with x and z position parameters at all three elemental sites being modulated as one moves along the c-axis. The resulting crystal structure can be conveniently described within the superspace formalism in (3 + 1) dimensions. The modulation vector, after initially strong temperature dependence, approaches a value close to qnuc = (0 0 0.35). Below TN = 2.8 (1) K, CeRuSn orders antiferromagnetically with a propagation vector qmag = (0 0 0.175), i.e. with the magnetic unit cell doubled along the c-axis direction with respect to the incommensurate crystal structure. Ce moments appear to be nearly collinear, confined to the a-c plane, forming ferromagnetically coupled pairs. Their magnitudes are modulated between 0.11 and 0.95 μB as one moves along the c-axis.
Baryon number violation (BNV) in R-parity violating (RPV) supersymmetry is studied with a focus on ΔB = 2 processes which allow neutron-anti-neutron (n-n) oscillations. Simplified RPV-SUSY models, ...including only the relevant superpartners and couplings, are considered. Constraints from flavour physics, searches at the Large Hadron Collider and searches at dedicated BNV experiments are quantified for the various scenarios at the TeV scale. It is also shown that a proposed n-n experiment at the European Spallation Source has a sensitivity to a mass scale for new physics that goes beyond all other experiments and up to the PeV scale for certain regions of parameter space.
The crystal chemistry of ternary equiatomic europium compounds EuTX (T = transition metal; X = element of the III, IV, or V main group) is reviewed. Besides preparation techniques we have especially ...focused on the structure−property relationships and peculiarities in chemical bonding. A main interest in these compounds is the valence state of the europium atoms. The magnetic susceptibility and electrical conductivity data, 151Eu Mössbauer spectroscopic results and LIII X-ray absorption experiments are discussed in detail.
The low-temperature heat capacity of knorringite garnet (Mg
3
Cr
2
Si
3
O
12
) was measured between 2 and 300 K, and thermochemical functions were derived from the results. The measured heat capacity ...curves show a sharp lambda-shaped anomaly peaking at around 5.1 K. Magnetic susceptibility data show that the transition is caused by antiferromagnetic ordering. From the
C
p
data, we suggest a standard entropy (298.15 K) of 301 ± 2.5 J mol
−1
K
−1
for Mg
3
Cr
2
Si
3
O
12
. The new data are also used in conjunction with previous experimental results to constrain ∆
H
f
° for knorringite.
The reaction of either V2F6·4H2O or a mixture of 60 wt % VF2·4H2O and 40 wt % VF3·3H2O with a water-saturated gaseous mixture of 15–20 vol % hydrogen in argon leads to the formation of a new ...polymorph of V3O5 crystallizing in the orthorhombic anosovite-type structure. Quantum-chemical calculations show that the anosovite-type structure is about 15 kJ/mol less stable than the corresponding monoclinic Magnéli phase. In addition, there are no imaginary modes in the phonon density of states, supporting the classification of the anosovite-type phase as a metastable V3O5 polymorph. Susceptibility measurements down to 3 K reveal no hint for magnetic ordering.
Gd{sub 4}Co{sub 2}Mg{sub 3} (Nd{sub 4}Co{sub 2}Mg{sub 3} type; space group P2/m; a=754.0(4), b=374.1(1), c=822.5(3) pm and beta=109.65(4){sup o} as unit cell parameters) was synthesized from the ...elements by induction melting in a sealed tantalum tube. Its investigation by electrical resistivity, magnetization and specific heat measurements reveals an antiferromagnetic ordering at T{sub N}=75(1) K. Moreover, this ternary compound presents a metamagnetic transition at low critical magnetic field (H{sub cr}=0.93(2) T at 6 K) and exhibits a magnetic moment of 6.3(1) mu{sub B} per Gd-atom at 6 K and H=4.6 T. Due to this transition the compound shows a moderate magnetocaloric effect; at 77 K the maximum of the magnetic entropy change is DELTAS{sub M}=-10.3(2) J/kg K for a field change of 0-4.6 T. This effect is compared to that reported previously for compounds exhibiting a magnetic transition in the same temperature range. - Graphical abstract: Temperature and field dependences of the magnetic entropy change for Gd{sub 4}Co{sub 2}Mg{sub 3} deduced from the magnetization measurements. DELTAS{sub M,F-}>{sub AF}{sup PEAK} and DELTAS{sub M,P-}>{sub F}{sup PEAK} denote the peak entropy changes, respectively, for the ferromagnetic to antiferromagnetic metamagnetic transition and for the paramagnetic to ferromagnetic ordering transition.
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► Totally delithiated Li4Pt3Si (Pt3Si) is metastable and keeps mother structure. ► Li binding energy range { −1.1–1.5eV} is intermediate between LiMO2 and LixSi binaries. ► ...Differentiated Li bonding with Pt according to lattice sites with stronger bonding.
The electronic structure of rhombohedral Li4Pt3Si (space group R32) is examined from ab initio with an assessment of the properties of chemical bonding relating to the presence of different Li and Pt Wyckoff sites. The structure with totally de-intercalated Li keeps the characteristics of the pristine compound with a reduction of the volume albeit with less cohesive energy. The binding energies of Li point to different bonding intensities according to their different Wyckoff sites and indicate the possibility of delithiation.
Li0.44Eu3B3N6 was synthesized from the metathesis reaction of Li3BN2 and EuCl3 at 850°C. Li0.44Eu3B3N6 crystallizes in the trigonal space group R3¯c (No. 167) with a=12.0225(2)Å, c=6.8556(2)Å and ...Z=6. In the crystal structure, isolated, planar cyclic B3N69− units are charge-balanced by the mixed-valence Eu3+/Eu2+ and Li+ cations. Li+ occupies partially (44%) the Wyckoff site 6b and is sandwiched between the B3N69− anions. Mössbauer spectroscopy results show the resonance lines of Eu2+ and Eu3+, respectively, indicating the heterogeneous mixed valency of the Eu atoms. X-Band ESR investigations between 5 and 300K reveal an intense signal over the whole temperature range originating from Eu2+. Magnetic susceptibility measurements indicate a Curie–Weiss behavior with an experimental effective magnetic moment of μeff=8.28μB per formula unit.
Single crystals of Li0.44Eu3B3N6 was obtained from the metathesis reaction of Li3BN2 and EuCl3.151Eu Mössbauer, ESR and magnetic susceptibility measurements reveal the heterogeneous mixed valency of the Eu atoms. Display omitted
•Single crystals of Li0.44Eu3B3N6 was obtained from the metathesis reaction of Li3BN2 and EuCl3 at 850°C.•Crystal structure is built up by isolated, planar cyclic B3N69− units which are surrounded by mixed valence Eu3+/Eu2+.•Li+ occupies partially (44%) the site 6b and is sandwiched between the B3N69− anions.•The 151Eu Mössbauer spectroscopy, electron spin resonance spectroscopy and magnetic susceptibility measurements confirm the heterogeneous mixed valency of Eu.
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