Ultrasonic attenuation in Niobium Oxide(NbO) due to phonon-phonon interaction

Ultrasonic attenuation due to phonon-phonon interaction and thermo elastic mechanism have been evaluated in NbO along (110) direction in the temperature range 100-500K. The second and third order elastic constants are also evaluated for the evaluation of ultrasonic attenuation and other associated parameters. The ultrasonic attenuation due to phonon-phonon interaction is predominant over thermo elastic loss in this material. The results are discussed in correlation with thermo elastic properties of NbO.

Derivation of Magnetostrictive Losses from Admittance Spectra

There are three types of losses for magnetostrictors, elastic loss, magnetic loss and piezomagnetic coupling loss, similar to the loss mechanism of a piezoelectric (elastic, dielectric and piezoelectric losses) that our group has established recent years. By introducing these losses factors we can characterize magnetostrictive losses using complex parameters. Here we derived the relationship of mechanical quality factors and losses factor based on admittance spectra expression we have established previously. By measuring accurately the mechanical quality factors QA for the resonance and QB for the anti-resonance in the admittance/impedance curve, we can derive these three physical losses to characterize magnetostrictive hysteresis loss.

Characterization of Magnetostrictive Losses Using Complex Parameters

Loss characterization in magnetostrictors is one of the key issues for realizing reliable magnetomechanical transducers. Concerning with the hysteresis minor loop within a relatively linear area of magnetostrictive curve, there are three types of losses, elastic loss, magnetic loss and piezomagnetic coupling loss, similar to the loss mechanism of a piezoelectric (elastic, dielectric and piezoelectric losses) that our group has established recent years. By measuring accurately the mechanical quality factors QA for the resonance and QB for the anti-resonance in the admittance/impedance curve, we can derive these three physical losses. By introducing these losses factors we can characterize magnetostrictive losses using complex parameters.

Mechanical Spectroscopy of Silicon as a Low Loss Material for High Precision Mechanical and Optical Experiments

The paper summarises systematic studies of the mechanical loss of crystalline silicon at low temperatures from 300 to 5 K. Thermo-elastic loss is discussed as a main contribution in thin samples. A numerical method based on a finite element analysis is presented to determine the thermo-elastic loss of arbitrarily shaped samples. Additionally, mechanical loss associated with oxygen is investigated in Czochralski grown silicon bulk samples. The process has the activation energy of about 168 meV. An orientation dependency of the loss is observed. The lowest loss reported in this paper was achieved with a cylindrical bulk sample having a diameter of 110 mm and a length of 200 mm at around 5 K and a resonant frequency of about 22.3 kHz.