Intrinsic dissipation mechanisms in metallic glass resonators

Abstract

Micro-and nano-resonators have important applications including sensing, navigation, and biochemical detection. Their performance is quantified using the quality factor Q, which gives the ratio of the energy stored to the energy dissipated per cycle. Metallic glasses are a promising materials class for micro-and nano-scale resonators since they are amorphous and can be fabricated precisely into complex shapes on these lengthscales. To understand the intrinsic dissipation mechanisms that ultimately limit large Q-values in metallic glasses, we perform molecular dynamics simulations to model metallic glass resonators subjected to bending vibrations. We calculate the vibrational density of states, redistribution of energy from the fundamental mode of vibration, and Q versus the kinetic energy per atom K of the excitation. In the linear and nonlinear response regimes where there are no atomic rearrangements, we find that Q → ∞ (since we do not consider coupling to the environment). We identify a characteristic Kr above which atomic rearrangements occur, and there is significant energy leakage from the fundamental mode to higher frequencies, causing finite Q. Thus, Kr is a critical parameter determining resonator performance. We show that Kr decreases as a power-law, Kr ∼ N −k , with increasing system size N , where k ≈ 1.3. We estimate the critical strain γr ∼ 10 −8 for micron-sized resonators below which atomic rearrangements do not occur, and thus large Q-values can be obtained when they are operated below γr. We find that Kr for amorphous resonators is comparable to that for resonators with crystalline order. arXiv:1907.00052v1 [cond-mat.mtrl-sci] 28 Jun 2019 AB = 1.5, σ AA = 1.0, σ BB = 0.88, and σ AB = 0.8. All atoms have the same mass m. The energy, length, and pressure scales are given in terms of AA , σ AA , and AA /σ 3 AA , respectively.

Nanotube formation from self-curling nanofilms driven by intrinsic surface-stress imbalance

“…Nanosized materials [1], such as nanowires [2], nanoporous materials [3], nanobeams [4,5], nanofilms [6,7], nanotubes [8], and nanoparticles [9][10][11], are of great importance in nanoelectromechanical systems (NEMS). They are applied as nanoresonators [12,13], nanoactuators [14,15], nanosensors [16,17], and so on. Interface and surface effects strongly affect mechanical behavior of nanosized materials [18,19].…”