NMR, Magnetic Susceptibility and Electronic Specific Heat of Nb and Mo Metals and Nb-Tc and Nb-Mo Alloys

Ostenburg, D. O. Van; Lam, D. J.; Shimizu, Masao; Katsuki, Akio

doi:10.1143/jpsj.18.1744

Cited by 68 publications

(6 citation statements)

References 14 publications

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“…Nb-Tc (Niobium -Technetium). The phase diagram of the system Nb-Tc is not known and only one intermetallic compound, NbTc 3 (metallic and superconductor) has been reported with αMn structure [9,10,47,[241][242][243]365]. The compound NbTc 3 is classified as phase Nb 0.15 Tc 0.85 in the Pauling File [10].…”

Section: Nb-ru (Niobium -Ruthenium)mentioning

confidence: 99%

Accuracy of ab initio methods in predicting the crystal structures of metals: A review of 80 binary alloys

Curtarolo

Morgan

Ceder

2005

Calphad

332

320

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systems in which the ab initio method predicts that no compounds are stable). A detailed comparison to experimental data confirms the high accuracy with which ab initio methods can predict ground states. A 2 B 2 hcp superstructure for RhRu, and an A 2 B 4 hcp superstructure for RhRu 2 (Appendix (XI)). In addition, we find two new crystal structures which are not superstructures of fcc, bcc or hcp: MoZr 3 and Mo 5 Ti (for Mo 5 Ti, MoZr 5 , and Nb 5 Ru) (Appendix (XII)). II. THE LIBRARY: ALLOYS AND STRUCTURESBinary alloys. Our calculated library contains 80 binary intermetallic alloys. The alloys include the binaries that can be made from row 5 transition metals, as well as some systems with Aluminum, Gold, Magnesium, Platinum, Scandium, Sodium, Titanium, and Technetium. The alloys are: AgAu, AgCd, AgMg, where the superscript * indicates the systems in which the high throughput ab initio method predicts that no compounds are stable: 57 alloys form compounds and 23 are non compound forming.Structures and their prototypes. The library contains 176 crystal structures. Many of these have the same structure type but with different compositions of occupancies, for example, AB 3 and A 3 B (also AB and BA if the point groups of atomic positions of A and B are different), so the number of distinct prototypes is 101. The various concentrations are listed in the table below.TcZr-B2 TABLE 6: Experimentally unknown, non-identified or speculated compounds and ab initio predictions (21 entries). 48 C. Experimental solid solutions, two-phases and "not studied" regions and possible ab initio predictions Experimental non-compound ⇔ ab initio compound System Experimental resultAb initio result Ag-Au short-range order 950 • C Ag 4 Au-D1a/tie-line Ag-Au short-range order 950 • C Ag 3 Au-L1 2 /D0 23 /Al 3 Pu/NbPd 3 /D0 22 /D0 24 Ag-Au short-range order 950 • C Ag 2 Au-C37/MoPt 2 Ag-Au short-range order 950 • C AgAu-L1 0 Ag-Au short-range order 950 • C AgAu 2 -C37/MoPt 2 Ag-Au short-range order 950 • C AgAu 3 -L1 2 /D0 22 /D0 23 Ag-Cd fcc solid solution Ag 3 Cd-D0 22 /D0 24

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Section: Nb-ru (Niobium -Ruthenium)mentioning

confidence: 99%

Accuracy of ab initio methods in predicting the crystal structures of metals: A review of 80 binary alloys

Curtarolo

Morgan

Ceder

2005

Calphad

332

320

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“…Depehding on which curves are used, the Knight shift data may be interpreted in a [157], V-Cr [157,158], V-Tc [157], V-Fe [159], V-Ru [160] , V-H [161] , Nb-H [162] , Nb-Tc [163], Zr-Nb and Nb-Mo [164] . (b) Ti-V [165] , V-Cr [157,165], V-Tc [157], Zr-Nb [164], Nb-Mo [163,164] , Nb-Re and Nb-Tc [163]. (c) Ti-V and V-Cr [164 ,166,167] , V-Fe [164], Zr-Nb andNb-Mo [168] .…”

Section: Concentration In Transition Metal Alloysmentioning

confidence: 99%

“…'If, as well as T t data and the Korringa relation [27], to de rive the various contributions to .'lf. For example , the r es ults of figure 16 have been rationalized [24,163,164] by usin g a two-band model for the Pauli term, as in eq (23) 10), admixture and variations of admixture of this magnitude are not unreasonable. This model is more obviously appropriate to the TiFe t-.…”

Section: Concentration In Transition Metal Alloysmentioning

confidence: 99%

Relevance of knight shift measurements to the electronic density of states

Bennett

Watson

Carter

1970

J. RES. NATL. BUR. STAN. SECT. A.

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The Knight shift, % , measures th e magne ti c hype rfin e fi eld at th e nucleu s produ ced by th e conducti on e lec tro ns whi c h are po la ri ze d in a ma gne ti c fi e ld. Kni ght s hifts are ofte n dominated by th e Pauli term a nd , in it.s mo st s impl e form , can be writte n as % = (a) x p. H ere XP is the conduction electron Pauli s pin s usce ptibility whic h de pe nd s on th e de nsity of states at th e Fe rmi le vel, N(EF), and (a ) is an a ve rage magneti c hype rfin e couplin g' cons tant associated with th e wav e function characte r at the nu c le us, 1

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“…we show in Fig. 6 the K(93Nb) points obtained by Van Ostenburg et al, for the Nb-Tc alloys [21] and the straight line representing the K(93Nb) values obtained by Alexander et al 1221, for the Nb-Mo system. The measurements on NbD, reported here extend this similarity up to almost the NbD,,, composition.…”

Section: Nb Knight Shiftmentioning

confidence: 64%

Deuteron and Niobium‐93 Magnetic Resonance Study of Niobium Deuterides

Barnes¹,

Roenker²,

Brooker³

1976

Ber Bunsenges Phys Chem

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Ker.i~yutrt~ri~ppo~resonanz Mngnetische Kernresonnnz / Phnsenunn.vandlungen 1 Stoffeigenscliuflen Niobium deuterides in the composition range NbD,,,, -NbD,,,, were investigated by means of deuteron and 93Nb magnetic resonance over the temperature range 4.2-420 K. The 0-a transition, in the temperature range 340-415 K for these compounds, is sharply defined by the extinction of the deuteron quadrupole interaction as well as by the appearance of the central component of the 93Nb spectrum when the cubic a phase is formed. These results are discussed in relation to other determinations of the P-a transition temperature. N o other significant changes in the deuteron magnetic resonance spectrum are observed, down to 4.2 K. at which temperature the quadrupole coupling constants are essentially equal. with an average value, e Z q Q / h = 33.0 kHz. The temperature dependent behavior of the 9'Nb resonance spectrum indicates that the boundary between the a + [3 and P regions of the Nb-H(D) phase diagram must pass between the compositions NbD,,,, and NbDo R Z at 300 K. The NMR observations d o not furnish positive support for the occurrence of the 6 and E phases nor for the occurrence of the cubic y phase, but they are not incompatible with the occurrence of these phases. These observations may reflect an intrinsic insensitivity of the deuteron quadrupole interaction to long range ordering of the deuterium in the lattice. Measurements of the 9."b Knight shift are in close agreement with the shifts obtained in Nb-Mo and Nb-Tc alloys. and suggest that up to this relatively high deuterium content (D/Nb = 0.88) the deuterium continues to yield its electron to the conduction band of the metal.Im Temperaturbereich 4.2 -420 K wurden die Deuteriden von Niob im Zusammensetzungsbereich NbD,,,, -NbD,,,, mittels Deuteronund "'Nb-NMR-Spektroskopie untersucht. Der P-a-Phasenubergang dieser Verbindungen erfolgt im Temperaturbereich 340-41 5 K und wird durch die Ausloschung der Deuteron-Quadrupol-Wechselwirkung, bzw. durch die Erscheinung der y3Nb Resonanz, beim Erreichen der kubischen a-Phase genau definiert. Diese Resultate werden in Verbindung mit anderen Bestimmungen der P-a-Ubergangstemperatur besprochen. Bei Abkiihlung bis 4.2 K. der Temperatur bei der die Quadrupol-Kopplungskonstanten unabhangig von Zusammensetzung praktisch denselben Wert haben ( e 2 q Q / h = 33,O kHz), wurden keine wesentliche Anderungen des NMR-Spektrums beobachtet.Die Temperaturabhangigkeit des "Nb Resonanzspektrums zeigt daD bei 300 K die Grenze zwischen den a + P-und P-Gebieten desNb -H/D)-Phasendiagramms zwischen den Zusammensetzungen NbD,,,, und NbD,,,, Iauft. Die NMR-Beobachtungen besorgen keine positive Unterstiitzung zum Auftreten der 5-und E-Phasen weder zum Auftreten der kubischen y-Phase. Sie sind doch mit dem Existenz dieser Phasen nicht unvereinbar. Diese Beobachtungen wiederspiegeln vielleicht eine wesentliche Unempfindlichkeit der Deuteron-Quadrupol-Wechselwirkung zur weitreichend Gitter-Einordnung des Deuterium. Messungen der 93Nb Knight-shift sti...

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NMR, Magnetic Susceptibility and Electronic Specific Heat of Nb and Mo Metals and Nb-Tc and Nb-Mo Alloys

Cited by 68 publications

References 14 publications

Accuracy of ab initio methods in predicting the crystal structures of metals: A review of 80 binary alloys

Accuracy of ab initio methods in predicting the crystal structures of metals: A review of 80 binary alloys

Relevance of knight shift measurements to the electronic density of states

Deuteron and Niobium‐93 Magnetic Resonance Study of Niobium Deuterides

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