Gradual Cerium Valence Change in the Solid Solution CeRu1–xPdxAl (x = 0.1–0.9)

Niehaus, Oliver; Janka, Oliver

doi:10.1002/zaac.201500139

Cited by 9 publications

(8 citation statements)

References 31 publications

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“…The obtained energy difference between the two possible ground states is E ex / k B = 986(1) K; the spin fluctuation temperature T sf = 692(2) K, and the stable Ce 3+ contribution is n = 0.0208(1). This leads to a cerium valence of +3.29 at 3 K and +3.24 at 300 K (Figure S4); hence, the tetravalent oxidation state gets depopulated at higher temperatures, in line with observations in the literature. − …”

Section: Resultssupporting

confidence: 85%

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Intermetallic RE₆T₅Al₇ Phases (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu; T = Ru, Ir): Diversity in their Magnetic, Magnetocaloric, and Critical Properties

et al. 2019

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Over 20 new compounds of the RE6T5Al7 series (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu; T = Ru, Ir; Yb6Ir5Ga7 type structure; superstructure of MgZn2; fully ordered Nb6.4Ir4Al7.6 type) have been synthesized. They crystallize in the hexagonal crystal system with space group P63/mcm. Their lattice parameters are in the ranges of a = 935–963 and c = 851–874 pm for the RE6Ru5Al7 and a = 913–966 and c = 825–865 pm for the RE6Ir5Al7 series. Four structures (Ho6Ru5Al7, Yb6Ru4.68(1)Al7.32(1), Sc6Ir5Al7, and Ho6Ir4.53(1)Al7.47(1)) have been refined from single-crystal data, indicating fully ordered structures for Ho6Ru5Al7 and Sc6Ir5Al7; however, T/Al mixing was observed on one crystallographic site for Ho6Ir4.53(1)Al7.47(1) and on two sites for Yb6Ru4.68(1)Al7.32(1). The Sc-, Y-, and Lu-containing compounds exhibit Pauli paramagnetism in line with a filled d band for Ru and Ir. Ce6Ru5Al7 exhibits mixed-valent behavior, while Yb6Ru5Al7 is solely trivalent. The other compounds exhibit paramagnetism and ferromagnetic phase transitions up to temperatures of T C = 83.4(1) K for Gd6Ru5Al7. In addition to the basic magnetic characterizations and studies of the electrical resistivity and heat capacity, the magnetocaloric properties of Gd6Ru5Al7, Tb6Ru5Al7, and Dy6Ru5Al7 have been investigated, revealing magnetic entropy changes of −ΔS M max = 6.2(1), 7.7(1), and 5.4(1) J kg–1 K–1 (0 → 5 T) and relative cooling powers RCP = 242, 207, and 135 J kg–1, respectively. For a deeper insight into the second-order magnetic phase transitions, the critical behavior was investigated according to the scaling hypothesis. The critical behavior of Gd6Ru5Al7 is in accordance with the mean-field theory; the critical exponents of Tb6Ru5Al7 and Dy6Ru5Al7, however, deviate strongly from this universality class. For comparison of the structural and magnetic properties, the thus far unstudied members of the RERuAl series (RE = Sc, Y, Sm, Gd–Lu; MgZn2 type) have additionally been prepared and characterized.

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Section: Resultssupporting

confidence: 85%

“…This is indicative of valence fluctuations of the cerium atoms, as e.g. observed in CeRuSn or in the solid solutions CeRu 1– x Ni x Al, CeRu 1– x Pd x Al, or CeRh 1– x Ru x Sn . The susceptibilities of these valence fluctuating materials can be described by the IFC (interconfiguration fluctuation) model, developed by Sales and Wohlleben .…”

Section: Resultsmentioning

confidence: 90%

Intermetallic RE₆T₅Al₇ Phases (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu; T = Ru, Ir): Diversity in their Magnetic, Magnetocaloric, and Critical Properties

et al. 2019

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“…Especially cerium containing compounds have gathered a lot of attention since they exhibit various highly interesting physical features, e.g. Kondo behavior (CeAl 2 , CeAuAl), superconductivity (CeCu 2 Si 2 , CeCoIn 5 ), heavy fermion behavior (CeAl 3 ), colossal magneto resistance (CMR, Ce 3 Cu 3 Sb 4 ) or valence fluctuations (CeRu 1– x Ni x Al, CeRu 1– x Pd x Al). These phenomena are caused by the two possible oxidation states, Ce 3+ (4 f 1 ) being paramagnetic and Ce 4+ (4 f 0 ) being diamagnetic.…”

Section: Introductionmentioning

confidence: 99%

“…The lattice parameters of the averaged hexagonal structure were refined from powder X-ray diffraction experiments and agree well with previous reports on these compounds. The ) or valence fluctuations (CeRu 1-x Ni x Al, [12] CeRu 1-x Pd x Al [13] ). These phenomena are caused by the two possible oxidation states, Ce 3+ (4f 1 ) being paramagnetic and Ce 4+ (4f 0 ) being diamagnetic.…”

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confidence: 99%

Magnetic Properties of theRE₂Pt₆X₁₅(RE= Y, La–Nd, Sm, Gd–Lu;X= Al, Ga) Series

2020

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The members of the RE2Pt6Al15 (RE = Ce–Nd, Sm, Gd–Yb) and RE2Pt6Ga15 (RE = Y, La–Nd, Sm, Gd–Lu) series have been synthesized from the elements via arc‐melting followed by annealing in an induction furnace. Isotypism of Ho2Pt6Al15 with orthorhombic (3+1)D commensurately modulated Sc2Pt6Al15 [Cmcm(α,0,0)0s0, α = 2/3] was observed from single‐crystal diffraction data. The diffraction pattern shows the same satellite reflections pattern as the prototype, therefore the same modulated superstructure was refined. Full ordering of the Pt and Al atoms within the [Pt6Al15]δ– polyanion was observed. The lattice parameters of the averaged hexagonal structure were refined from powder X‐ray diffraction experiments and agree well with previous reports on these compounds. The X‐ray pure polycrystalline samples of both series were studied with respect to their magnetic properties. The susceptibility data of all investigated compounds show experimental magnetic moments close to the free ion values of the RE3+ cations and antiferro‐/ferrimagnetic ordering at low temperatures with Curie temperatures up to TC = 16.8(1) K for Gd2Pt6Ga15. Both, Sm2Pt6Al15 and Sm2Pt6Ga15 show the typical van Vleck type behavior along with antiferromagnetic ordering at a Néel temperature of TN = 4.5(1) K (Al) and ferrimagnetic ordering at TC = 6.5(1) K (Ga). Yb2Pt6Al15 exhibits ytterbium in the trivalent oxidation state, while for Yb2Pt6Ga15 a divalent state of the Yb atoms was observed.

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“…[ 15 ] In Ref. [16], authors calculated cerium valence in

{CeRu}_{1 - x} {Pd}_{x} Al

compounds with adding different amount of impurity. Computations are performed using the interconfiguration fluctuation model that mimics hybridization effects through a renormalized temperature and the range of valence is from 3.15 to 3.32.…”

Section: Resultsmentioning

confidence: 99%

Noninteger Valence in Ce‐Based Compounds

Ponomarova

Koval

2023

Physica Status Solidi (b)

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Herein, a simple thermodynamic approach using the Helmholtz free energy is proposed to estimate the noninteger valence in Ce‐based compounds at the γ→α phase transition. The idea of an electron phase transition within Anderson–Kondo model is used as a microscopic mechanism and applied to Ce–X (X = Y, Al–Sc) within 0–16 at% of X. In the suggested approach, valence of Ce–X compounds depends on volume collapse and the temperatures of start and finish of phase transition as well as external pressure, which can induce γ→α phase transition, and increases with rising the amount of impurity.

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Gradual Cerium Valence Change in the Solid Solution CeRu_1–xPd_xAl (x = 0.1–0.9)

Cited by 9 publications

References 31 publications

Intermetallic RE₆T₅Al₇ Phases (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu; T = Ru, Ir): Diversity in their Magnetic, Magnetocaloric, and Critical Properties

Intermetallic RE₆T₅Al₇ Phases (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu; T = Ru, Ir): Diversity in their Magnetic, Magnetocaloric, and Critical Properties

Magnetic Properties of theRE₂Pt₆X₁₅(RE= Y, La–Nd, Sm, Gd–Lu;X= Al, Ga) Series

Noninteger Valence in Ce‐Based Compounds

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Gradual Cerium Valence Change in the Solid Solution CeRu1–xPdxAl (x = 0.1–0.9)

Cited by 9 publications

References 31 publications

Intermetallic RE6T5Al7 Phases (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu; T = Ru, Ir): Diversity in their Magnetic, Magnetocaloric, and Critical Properties

Intermetallic RE6T5Al7 Phases (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu; T = Ru, Ir): Diversity in their Magnetic, Magnetocaloric, and Critical Properties

Magnetic Properties of theRE2Pt6X15(RE= Y, La–Nd, Sm, Gd–Lu;X= Al, Ga) Series

Noninteger Valence in Ce‐Based Compounds

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Gradual Cerium Valence Change in the Solid Solution CeRu_1–xPd_xAl (x = 0.1–0.9)

Intermetallic RE₆T₅Al₇ Phases (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu; T = Ru, Ir): Diversity in their Magnetic, Magnetocaloric, and Critical Properties

Intermetallic RE₆T₅Al₇ Phases (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu; T = Ru, Ir): Diversity in their Magnetic, Magnetocaloric, and Critical Properties

Magnetic Properties of theRE₂Pt₆X₁₅(RE= Y, La–Nd, Sm, Gd–Lu;X= Al, Ga) Series