Low-Temperature Dissipation Peak in Niobium

Bordoni, P. G.; Nuovo, M.; Verdini, L.

doi:10.1103/physrev.123.1204

Cited by 30 publications

(11 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our own results, as weil as evaluation of measurements that --bulk Pd have been carried out earlier by Kubicka [12], allow a separation of the reduction of X into two parts. One of these is due to the different electronic properties of the metal dose to the !…”

Section: Pd Btacksupporting

confidence: 52%

Magnetic Susceptibility and Equilibrium Diagram of PdH_n

Frieske

Wicke

1973

Ber Bunsenges Phys Chem

280

100

View full text Add to dashboard Cite

The limits nαmax and nβmin of the two‐phase region of PdHn can only roughly be estimated from the shape of the equilibrium isotherms pH2(n). Other methods applied so far do not yield more accurate results. More precise values can be obtained, however, from measurements of the magnetic susceptibility x as a function of the hydrogen content n at various temperatures. Such x(n) isotherms have been measured at temperatures between 20 and 300°C and H2 pressures up to 140 atm (0 · n · 0.8), using samples of Pd wire (1 mm) and Pd foil (33 μm). In the homogeneity range isotherms for adsorption and desorption were identical, in the two‐phase region, however, hysteresis was always observed. Here the desorption curve was taken as the equilibrium isotherm, and was applied to determine the values of nαmax and nβmin by extrapolation. Measurements on Pd black in the same region of pressure and temperature showed a number of peculiarities, for instance smaller values of susceptibility and smaller hysteresis loops as compared with bulk Pd. These can be attributed to the large specific surface area of Pd black as well as to its strongly distorted lattice structure. By means of the measurements on bulk Pd the position of the critical point of the palladium‐hydrogen system could be redetermined with rather high precision: Tc = 291 ± 2°C; nc = 0.250 ± 0.005 mol H/mol Pd; Pc = 19.7 ± 0.2 atm H2. The measurements on Pd‐black yielded within the limits of error the same values for the critical temperature and the critical pressure, whereas the value of the H/Pd ratio, properly corrected, was found to be a bit higher, namely nc = 0.260 ± 0.005.

show abstract

Section: Pd Btacksupporting

confidence: 52%

Magnetic Susceptibility and Equilibrium Diagram of PdH_n

Frieske

Wicke

1973

Ber Bunsenges Phys Chem

280

100

View full text Add to dashboard Cite

show abstract

“…A few years after the mechanism of the Bordoni-type relaxation processes in fcc metals had become the subject of discussion, a search for analogous processes in bcc metals began [52][53][54][55][56][57][58]. By that time, striking differences between the deformation behaviour of fcc and bcc metals were already well established.…”

Section: Dislocations In Deformed Body-centred Cubic Metals 11mentioning

confidence: 96%

Progress and problems in the understanding of the dislocation relaxation processes in metals

Seeger

2004

Materials Science and Engineering: A

View full text Add to dashboard Cite

“…The dissipation maximum found at temperatures near 200 K can be explained by a so-called Arrhenius peak [28][29][30][31][32], indicative of a thermally activated relaxation process over a well-defined barrier height V (in constrast to the broad distribution governing the behaviour of the typical two-level defects in glassy material). The most likely candidate for these well-defined states might be the hydrogen defects present even in very clean LPCVD silicon nitride films [33].…”

mentioning

confidence: 99%

Signatures of two-level defects in the temperature-dependent damping of nanomechanical silicon nitride resonators

et al. 2014

View full text Add to dashboard Cite

The damping rates of high quality factor nanomechanical resonators are well beyond intrinsic limits. Here, we explore the underlying microscopic loss mechanisms by investigating the temperaturedependent damping of the fundamental and third harmonic transverse flexural mode of a doubly clamped silicon nitride string. It exhibits characteristic maxima reminiscent of two-level defects typical for amorphous materials. Coupling to those defects relaxes the momentum selection rules, allowing energy transfer from discrete long wavelength resonator modes to the high frequency phonon environment.PACS numbers: 85.85.+j,62.40.+i,63.50.Lm Silicon nitride (SiN) is a material widely used for resonant micro-and nanomechanical devices because of its superior mechanical properties [1][2][3][4][5][6][7][8][9][10][11][12]. The transverse flexural modes of string resonators fabricated from prestressed SiN thin films exhibit extremely high mechanical quality factors [2,[8][9][10]. They originate from the fact that an increase in tensile stress only slightly increases the mechanical damping rate Γ m , whereas it dramatically increases the resonance frequencies f m and thereby the quality factor Q = 2πf m /Γ m [8]. Nonetheless, the observed damping is significantly larger than expected from intrinsic loss mechanisms such as clamping losses caused by the direct radiation of phonons at frequency f m into the supporting clamping points [13,14] or by thermoelastic damping [15]. In an attempt to shed light on the limiting loss mechanisms, damping was found to be proportional to the local bending within the resonator and governed by both bulk and surface defects [8]. More recently, the damping has been shown to be dominated by T 1 -like energy relaxation processes [16]. Such processes involve a transfer of energy from discrete resonator modes at comparably low frequencies f m into the high frequency phonon bath that dominates the heat capacity and thermal conductivity. However, their different dispersion relations inhibit a direct energy transfer via two-particle scattering. It takes local defects to enable energy transfer into the bath via three particle scattering and to relax momentum conservation. Such defects are omnipresent in amorphous materials. For example, a local configurational change of the atomic structure gives rise to a double-well potential separated by an energy barrier, which at low temperatures can be modeled as a two-level system (TLS). These TLS are known to lead to characteristic maxima in the temperature dependence of the sound absorption in the temperature range of 10 to 100 K [17][18][19][20]. The signature of TLS has also been observed in the damping characteristics of a micromechanical silica resonator [21] and in a backaction-evading measurement on a SiN membrane performed at mK temperatures [22].To clarify whether the microscopic nature of the damping in high Q SiN nano resonators is dominated by local defect scattering induced by such two-level systems, we study the temperature-dependent damping of nanoscal...

show abstract

Low-Temperature Dissipation Peak in Niobium

Cited by 30 publications

References 6 publications

Magnetic Susceptibility and Equilibrium Diagram of PdH_n

Magnetic Susceptibility and Equilibrium Diagram of PdH_n

Progress and problems in the understanding of the dislocation relaxation processes in metals

Signatures of two-level defects in the temperature-dependent damping of nanomechanical silicon nitride resonators

Contact Info

Product

Resources

About

Low-Temperature Dissipation Peak in Niobium

Cited by 30 publications

References 6 publications

Magnetic Susceptibility and Equilibrium Diagram of PdHn

Magnetic Susceptibility and Equilibrium Diagram of PdHn

Progress and problems in the understanding of the dislocation relaxation processes in metals

Signatures of two-level defects in the temperature-dependent damping of nanomechanical silicon nitride resonators

Contact Info

Product

Resources

About

Magnetic Susceptibility and Equilibrium Diagram of PdH_n

Magnetic Susceptibility and Equilibrium Diagram of PdH_n