Vibrating Reed Research Articles

Structure, microstructure and magneto-elastic property study on Co40Ni29Al31 ferromagnetic shapememory alloy ribbon

Ferromagnetic shapememory Alloys having huge magnetic field and stress-induced strain are suitable materials for sensors and actuators. Ni2MnGa being the prototype of these materials and because of its brittleness alternative systems CoNiAl/Ga were recently developed. CoNiAl being a ductile material because of its two-phase microstructure and the large range of transformation temperatures. In this line, a ribbon with nominal composition Co40Ni29Al31 was prepared using melt-spun technique. The structure and microstructure of the sample was determined using XRD and SEM. The transformation temperatures were determined using four probe method using a cryocooler within the temperature range of 4 K to 350 K. The elastic and magneto-elastic properties were studied using a Vibrating reed method within the temperature 80 K to 300 K. A constant magnetic field of 300 Oe is applied with a coil wound on the cryostat of the vibrating reed setup. As was expected the sample has two phases of microstructure, from the XRD data, a high amount of β phase with a few amount of γ phase was found and it was also replicated in SEM photographs. The phase fractions were found by fitting the XRD data with Reitveld refinement. The transformation temperatures of the sample were obtained from the four probe resistivity measurements, and they are TMs = 133 K, TMf = 83 K, TAs = 130 K and TAf = 179 K. From the sound velocity and internal friction study without and with the magnetic field interesting results were found. The martensitic and inter martensitic transformations were suppressed with the application of magnetic field. It was clearly seen in the sound velocity change plots as a function of temperature and the same was replicated in the internal friction plots. Such studies through light on the magneto-elastic coupling-related issues and are quite useful for the application of these materials for the Micro Electro Mechanical Systems at different operating conditions.

Comprehensive Design Considerations and Noise Modeling of Preamplifier for MEMS Electrometry

The purpose of the work is to evaluate various intrinsic noise sources that limit the charge resolution of microelectromechanical systems (MEMS) vibrating-reed (VR) electrometers. We demonstrate a method of reducing total equivalent referred-to-input (RTI) noise voltage per square root hertz for an operational amplifier-based preamplifier (preamp) circuit topology. The proposed circuit’s noise model accurately describes the various noise sources and total RTI noise voltage is experimentally verified. The noise analysis clarifies the path toward a preamp with a noise floor limited by thermal noise due to low-valued shunt resistance at its input. Furthermore, during the charge measurement, a variation of sensitivity occurs by changing the isolation (or dc blocking) capacitor of the preamp. This phenomenon also affects the noise performance of the circuit and the overall charge resolution for the electrometer. RTI noise voltage of 290 nV/ $\surd $ Hz at 5.2 kHz was measured for 50 $\text{M}\Omega $ of shunt resistor and 2 pF of isolation capacitor to implement a prototype of the complete preamp, along with the MEMS device fabricated in silicon-on-glass (SOG) process. Finally, we present a charge resolution model of the proposed SOG-MEMS electrometry system. The model’s underlying design principles reveal low noise preamps accessible to the circuit designers without tangible circuitries and after-the-fact noise measurement.

Ni基超合金の薄板疲労試験における振動リード法の適用についての研究

Vibrating reed machine to thin plate fatigue test is a kind of resonance type, invented by Hirata 1995 as the method of a speaker unit was used as the vibrator. In the case of the fatigue evaluation of thin plate plane bending stress as typified by bellows are needed, it was expected as the effectual method. There are little research papers that made adequacy evaluations about absolute level of fatigue data. Furthermore, even though the test method is high-speed and simple, it doesn't become universal. And so, this paper is appeared to make adequacy evaluations of thin plate vibrating reed fatigue test with testing thin test pieces actually. In this time, adding the determined points of the displacement, and using a vibration exciter, accuracy is increased. Vibrating reed fatigue tests were carried out for Inconel 718 in ambient air using 5 mil and 8 mil notched specimens with 64 Hz and 110 Hz. Fatigue results appeared that the fatigue strength in vibration reed method was higher than that in rotating bending fatigue tests with 55 Hz reported by Kawagoishi et al. 2006. Then pointing out the stress field of crack tip in the difference of thickness, the calculations of each stress intensity factor conduced to the effect of thickness. The increase in fatigue strength of thin plate was caused by the reduction of stress intensity factor in the crack tip with early crack growth.

G040022 Vibrating reed法を用いた水素の属内拡散過程の観察([G04002]機械材料・材料加工部門一般セッション(2))

Vibrating reed (VR) technique can measure the Young's modulus which is dependent on the resonant frequency by making a thin board vibrate like a reed. In the previous report, it was shown that VR technique was effective as the way of measuring the degree of the absorption to the metal of hydrogen. Hence, the differences in the resonance frequency were found in some temperature range as a result of measuring the resonance frequency of the metal which absorbed hydrogen in hydrogen atmosphere, and that of the metal which didn't. In this report, after hydrogen was charged into sample SUS304 with the atmospheric pressure or 100MPa, changes in the resonance frequency were investigated in the diffusion process and in the separation process of hydrogen.

Vibration Reed Electrometer for Accurate Measurement of Electrical Currents Below 10 pA

The paper is about developing a home-built vibrating reed (VR) electrometer. The heart of the meter is a VR capacitor, which excels in a stable and low input leakage current of only 8 aA with a 2 aA noise for a 1 h measurement. This paper demonstrates that this makes the instrument ideal for the characterization of subtle charge effects in, for example, connectors and cables. The exceptional sensitivity of the electrometer is proven in a measurement of the leakage resistance of an air gap capacitor which results in a value of Rleak = (8.8 0.3) 1017 Omega, obtained at a test voltage of only 10 V. Calibration of the system with both a picoampere and a picocoulomb generator shows that the instrument has an accuracy of 15 parts in 106 (k = 1) at a current of 1 pA. As far as we are aware, this is the best uncertainty for a room temperature electrometer published so far

High-sensitivity vibrating reed studies of superconductors

Recent improvements in the vibrating reed (VR) technique permit precision studies of the mixed state of complex superconducting materials far below the upper critical magnetic field H c2. VR data for thin film, crystalline and ceramic (Ba 0.6K 0.4)BiO 3 samples demonstrate the sensitivity of the VR to microstructure and inhomogeneities, and a study of oNi 2B 2C reveals previously inaccessible vortex dynamical anomalies and minute details of a complex phase competition between magnetism and reentrant superconductivity. CeRu 2 VR data are reversible near H c2 where giant hysteresis is observed in DC magnetization data, but are hysteretic over an extended region at lower temperatures and fields, indicating vortex dynamics must be considered in testing the existence of unconventional pairing states proposed for this system.

Anomalous vortex dynamics in kappa -

Anisotropic superconducting flux-line behavior of single-crystal \ensuremath{\kappa}-[bis(ethylenedithio)tetrathiaful- valene${]}_{2}$Cu[N(CN${)}_{2}$]Br has been studied with dc magnetization and vibrating-reed (VR) techniques. A peak at ${\mathit{T}}^{\mathrm{*}}$(H) in the temperature dependence of the VR inverse quality factor 1/Q exhibits a shoulder for magnetic fields 0${\mathrm{\ensuremath{\mu}}}_{0}$H\ensuremath{\le}0.5 T parallel to the conducting ac plane. The shoulder becomes unresolved near a kink in T*(H) at ${\mathrm{\ensuremath{\mu}}}_{0}$H\ensuremath{\approxeq}0.7 T. Discontinuities in 1/Q and the VR frequency shift occur for 0.1\ensuremath{\le}${\mathrm{\ensuremath{\mu}}}_{0}$H\ensuremath{\le}1.3 T applied perpendicular to the ac plane and temperatures T\ensuremath{\le}20 K, well into the normal state. These anomalies are preliminary evidence for a field-induced magnetic phase transition and unconventional superconductivity.

Vibrating reed study of the flux line dissipation of ceramic and single-crystal (Ba, K)BiO3

Vibrating reed (VR) and dc and ac magnetic susceptibility measurements were performed on a nominal single crystal of composition (Ba0.64K0.36)BiO3 in an applied magnetic fieldH. Field-cooling and field-sweep data revealed multiple peaks in the reed dissipation 1/Q located below the superconducting transition temperatureT c (≈29.6 K forH=0). A shoulder or onset (with increasingT) of dissipation appears forT≤18 K, which may be a signature of a flux lattice melting transition. VR data for dense ceramic samples of composition (Ba0.625K0.375)BiO3 (Tc=28.6K) exhibit a relatively narrow and smooth peak in 1/Q that corresponds well to a broad, intermediate-temperature peak in the crystal data. Resistivity experiments demonstrate that the single ceramic peak occurs well below the temperature at which the electrical resistanceR≈0, suggesting that the higher-temperature crystalline peaks are positioned close to the upper critical field line and may be strongly dependent upon grain size or surface properties. Both ac and dc susceptibility data show no clear evidence for multiple phases or gross compositional inhomogeneities in the crystalline sample. Our results demonstrate that the VR technique is an extremely sensitive method to probe sample inhomogeneities and their role in flux pinning phenomena.

Double-peak in the dissipation of NbSe 2 vibrating reeds

Vibrating reed (VR) and electrical resistance measurements were performed on single-crystal NbSe 2 with hexagonal c-axis approximately parallel or perpendicular to an applied magnetic field, H. Field-cooling data revealed two peaks in the reed dissipation, 1/ Q. The upper peak (at T U) occurs near the temperature where R ≈ 0, and the lower peak is amplitude-dependent and hysteretic. T U is independent of frequency (Δ T U < 0.1 K for 100 Hz < ƒ < 50 kHz). An unusual peak in the temperature dependence of the frequency shift of the reed was also observed.

Vibrating reed studies on high-T c superconductors

We present vibrating reed (VR) measurements on single crystal and ceramic “1-2-3” and melt-processed polycrystalline Bi-based compounds in a wide range of temperature (4·2–100 K) and magnetic field (B=0–4 T). The “depinning line” (DL) determined by the VR technique is equivalent to the “irreversibility line” determined by magnetization and susceptibility measurements. A comparison of the results on single crystal and polycrystalline 1-2-3 compounds indicates that the VR technique is sensitive to the intragranular properties of the polycrystalline reed. It is found that the DL for 1-2-3 compounds is much steeper than that for Bi-based compounds, reflecting an intrinsically different pinning in both the materials, in agreement with the measured elastic coupling (Labusch constant α(B, T)).

Lower critical field of single crystal Y(Gd6%)Ba 2Cu 3O 6.83

Using the vibrating reed (VR) technique, the temperature dependence of the lower critical field B C1 (T) of a single crystal Y(Gd6%)Ba 2 Cu 3 O 6.83 has been measured. The deviation from perfect diamagnetism determined from the resonance frequency of the reed is consistent with the increase of the damping caused by the flux line motion. With magnetic field applied parallel to the ab plane we obtain B C1 (0) = 750 G. If the clean limit is assumed, the measured value of B C1 (0)/(T C· (dB C1 /dT) Tc ) = 0.51 ∓ 0.04 indicates the presence of strong coupling effects.

Flux-Line Pinning in a Superconducting Vibrating Reed

A thin ribbon of a superconducting material clamped at one end and excited to flexural vibrations may be used to study flux pinning. The resonance frequency, strongly enhanced in a longitudinal magnetic field, slightly decreases and the damping drastically increases when the flux lines are allowed to move relative to the pins. The reed may be further used as a sensitive magnetometer and to measure Bc1 (≦7mT) of ceramic high-Tc superconductors from which we made reeds.

Free Vibrating Reed Apparatus for the Measurement of Internal Friction and Young's Modulus down to 4 K

This paper describes in detail a freely vibrating reed apparatus which we have developed to study these low temperature dynamic mechanical properties of polymers (at approximately 5 cps). The apparatus is capable of measuring these properties from 4 up to 340 K. This method has the advantage over other methods of being relatively easy to set up and may be modified so more than one specimen can be investigated in a given temperature run. In addition measurements on the logarithmic decrement and Young's modulus of polystyrene are presented and compared with previous data.

Measurement of Photomagnetic Susceptibility by Means of a Vibrating Reed Balance

An apparatus employed for studying light-modulated changes in the magnetic susceptibility of semiconductors is described. Its chief parts are a flat reed spring from which the specimen is suspended, an electrostatic counter-balancing system, a frequency modulation phase sensitive motion detector, and a modulated light source. The light modulation operates at the mechanical frequency of reed and specimen, whose forced harmonic motion is proportional to the light-induced susceptibility changes. The chief advantages of this new method are the elimination of drifts due to changes in the nonmodulated part of the susceptibility, the excellent nonsynchronous noise elimination, and the high detection sensitivity, which was 10−11 cgs mass-susceptibility units at a value of H gradH of 107 gauss2/cm. Another incidental advantage is a simplicity and ruggedness not generally encountered in high sensitivity instruments.