Magnetischer und kalorischer Nachweis von Ordnungs-Umwandlungen in Kupfer-Mangan-Leigierungen

Kussmann, A.; Wollenberger, H.

doi:10.1007/bf00594008

Cited by 13 publications

(3 citation statements)

References 2 publications

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“…Annealing at about 450 "C for two hours practically destroys any SRO [9], on the other hand, the annealing will be sufficient to produce the (rather low) equilibrium concentration of vacancies at 450 "C which during the subsequent quenching process is too low to originate a detectable amount of SRO. Therefore, we consider this state to be one without an appreciable amount of SRO (curve d450q in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, these early publications already pointed out that it is the atomic SRO which in Q M n as well as in other spin glass systems like AuFe [6-81 and &Mn [8] is playing the dominant role with regard to the influence of ageinyon the magnetic properties. Although the tendency for short-range order is rather small in G M n as compared to the other systemsjust mentioned, its occurrence at concentrations above about 5 at% Mn was stated in 1956 by calorimetric measurements [9] and was further supported by quasi-elastic neutron diffraction investigations [ 101 later on. Finally, studies by neutron polarization analysis completely revealed the atomic and spin structure in CuMn [ l l , 121.…”

Section: Introductionmentioning

confidence: 91%

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The Influence of Tensile Deformation and Atomic Short-Range Order on the Susceptibility of CuMn Spin Glasses

Kahl

Neuhaus

Pinkvos

et al. 1990

phys. stat. sol. (a)

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The magnetic ac‐susceptibility of CuMn‐alloys, χ(T), proves to be a very sensitive probe, particularly near the cusp defining the spin glass temperature Tf[1], to detect variations of the structural state χ(T) increases with an increasing degree of atomic short – range order (SRO). It is shown that for well annealed specimens the amount of SRO and simultaneously χ(Tf) pass a minimum as function of the quenching temperature Tq at about Tq = 450°C. The normalized χ(T)‐curves considered as functions of the reduced temperaturesT/Tf are broader for a smaller amount of SRO. A plastic tensile deformation at room temperatrue causes an increase in χ(T). It is detectable already for 5 at% Mn and becomes very pronounced for 13 at% Mn. The effect vanishyes completely when the SRO is dissolved by quenching the sample after an anneal at 450°C. From that it is concluded that the tensile deformation generates a vacancy concentrtation high enough to produce an otherwise unattainable amount of SRO at room temperatrue.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

The Influence of Tensile Deformation and Atomic Short-Range Order on the Susceptibility of CuMn Spin Glasses

Kahl

Neuhaus

Pinkvos

et al. 1990

phys. stat. sol. (a)

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“…It is the aim of the present paper to present results of magnetisation and lowtemperature specific heat on Cu-Mn samples (5,8,13,16,20 and 30 at.% Mn) corresponding to two different but definite states of SRO: one state corresponds to the well established SRO state at 200"C, and the other to the state at 400°C (350°C for Cu-13 at.% Mn), which corresponds to a lower degree of SRO. The main question which should be answered in this way is: how do the above physical quantities vary as a function of concentration with respect to the degree of SRO 0953-8984/90/316593 + 09 $03.50 @ 1990 IOP Publishing Ltd reciprocal temperature of Cu-5 at.% Mn (0), Cu-8at.%Mn (A), Cu-l3at.%Mn (U), Cu-16 at.% Mn (V) and Cu-20 at.% Mn (+). and is there agreement with previous investigations [ 1-31?…”

Section: Introductionmentioning

confidence: 99%

Atomic short-range order and spin-glass behaviour in concentrated Cu-Mn alloys

Clad

Kuentzler

Pfeiler

1990

J. Phys.: Condens. Matter

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The effect of atomic short-range order (SRO) in Cu-Mn (5-30 at.% Mn) on the spin-glass properties is studied by measuring the magnetic behaviour and the low-temperature specific heat for two well defined equilibrium states of SRO. Usual spin-glass features are observed. The freezing temperatures Tf as well as the coefficient gamma * of the linear specific heat term appear to be not sensitive to SRO, whereas the amplitude of the peak susceptibility at Tf is drastically increased. The results are compared with previous work after different thermal treatments.

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Katalytische Untersuchungen an Legierungen. XXXIII. Die Parawasserstoff‐Umwandlung an Kupfer–Mangan‐und Silber–Mangan‐Legierungen

Engels¹

1969

Zeitschrift anorg allge chemie

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Es wurde die Parawasserstoff‐Umwandlung an Kupfer‐Mangan‐ und Silber–Mangan‐Legierungen der Zusammensetzung 4,8–31,6 At.‐% Mn (CuMn) bzw. 6,5–33,2 At.‐% Mn (AgMn) untersucht (Temperaturbereich der Messungen etwa 400–550°C). An CuMn‐Katalysatoren wird beim übergang von den Proben mit 19 At.‐% Mn zu solchen mit 21 At.‐% Mn ein deutlicher Abfall der scheinbaren Aktivierungsenergie sowie ein starker Anstieg der absoluten Geschwindigkeitskonstanten gefunden. Ein qualitativ analoges Verhalten beobachtet man an den AgMn‐Katalysatoren im Konzentrationsbereich von 11–14 At.‐% Mn. Für bestimmte Gruppen von Legierungen ergibt sich der Kompensationseffekt. Das katalytische Verhalten der Legierungen wird im Zusammenhang mit dem Auftreten lokalisierter Mn‐d‐Zustände, der Nahordnung sowie Sättigungsgrenze für den jeweiligen Mischkristall CuMn bzw. AgMn beschrieben.

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Magnetischer und kalorischer Nachweis von Ordnungs-Umwandlungen in Kupfer-Mangan-Leigierungen

Cited by 13 publications

References 2 publications

The Influence of Tensile Deformation and Atomic Short-Range Order on the Susceptibility of CuMn Spin Glasses

The Influence of Tensile Deformation and Atomic Short-Range Order on the Susceptibility of CuMn Spin Glasses

Atomic short-range order and spin-glass behaviour in concentrated Cu-Mn alloys

Katalytische Untersuchungen an Legierungen. XXXIII. Die Parawasserstoff‐Umwandlung an Kupfer–Mangan‐und Silber–Mangan‐Legierungen

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