Temperature Dependence Of Resonance Frequency Research Articles

Wireless Passive Sensor Technology through Electrically Conductive Media over an Acoustic Channel.

Hydrogen-based technologies provide a potential route to more climate-friendly mobility in the automotive and aviation industries. High-pressure tanks consisting of carbon-fiber-reinforced polymers (CFRPs) are exploited for the storage of compressed hydrogen and have to be monitored for safe and long-term operation. Since neither wired sensors nor wireless radio technology can be used inside these tanks, acoustic communication through the hull of the tank has been the subject of research in recent years. In this paper, we present for the first time a passive wireless sensor technology exploiting an ultrasonic communication channel through an electrically conductive transmission medium with an analog resonant sensor featuring a high quality factor. The instrumentation system comprised a readout unit outside and a passive sensor node inside the tank, coupled with geometrically opposing electromechanical transducers. The readout unit wirelessly excited a resonant sensor, whose temperature-dependent resonance frequency was extracted from the backscattered signal. This paper provides a description of the underlying passive sensor technology and characterizes the electric impedances and acoustic transmission as an electrical 2-Port to design a functional measurement setup. We demonstrated a wireless temperature measurement through a 10 mm CFRP plate in its full operable temperature range from -40 to 110 °C with a resolution of less than 1 mK.

Nanomechanical probing and strain tuning of the Curie temperature in suspended Cr2Ge2Te6-based heterostructures

Two-dimensional magnetic materials with strong magnetostriction are attractive systems for realizing strain-tuning of the magnetization in spintronic and nanomagnetic devices. This requires an understanding of the magneto-mechanical coupling in these materials. In this work, we suspend thin Cr2Ge2Te6 layers and their heterostructures, creating ferromagnetic nanomechanical membrane resonators. We probe their mechanical and magnetic properties as a function of temperature and strain by observing magneto-elastic signatures in the temperature-dependent resonance frequency near the Curie temperature, TC. We compensate for the negative thermal expansion coefficient of Cr2Ge2Te6 by fabricating heterostructures with thin layers of WSe2 and antiferromagnetic FePS3, which have positive thermal expansion coefficients. Thus we demonstrate the possibility of probing multiple magnetic phase transitions in a single heterostructure. Finally, we demonstrate a strain-induced enhancement of TC in a suspended Cr2Ge2Te6-based heterostructure by 2.5 ± 0.6 K by applying a strain of 0.026% via electrostatic force.

Phase equilibria and microwave dielectric properties in the ternary La2O3–TiO2–Nb2O5 system

High-temperature phase relations in the La2O3–TiO2–Nb2O5 ternary system were investigated at 1290 °C using SEM, EDS and XRD, and a subsolidus phase equilibrium diagram was constructed. It was demonstrated that the addition of the La1/3NbO3 to the La2O3:3TiO2 mixture completely stabilizes a perovskite-La2/3TiO3 compound, which is otherwise not stable at stoichiometric composition. On the other hand, a mixture La2O3:TiO2 =1:3 dissolves in La1/3NbO3 up to 15 mol% TiO2. Moreover, a newly defined composition of compound La30Ti16Nb4O87 formed in the La2O3-rich part of the system and a solid solution La3Ti5Nb10O39.5–La2Ti2Nb8O27 were proposed. In the binary subsystem LaTiNbO6-La0.462Ti0.386Nb0.614O3, the components exhibit opposite temperature dependence of resonant frequency in the microwave frequency range. Thus, the dielectric properties of the prepared ceramics can be tailored by varying the component concentration and thermally stable dielectric properties can be achieved for a composition with a LaTiNbO6/La0.462Ti0.386Nb0.614O3 molar ratio of 0.27.

Plasmon resonances and tachyon ghost modes in highly conducting sheets

Plasmon-polariton modes in two-dimensional electron gases have a dual field-matter nature that endows them with unusual properties when electrical conductivity exceeds a certain threshold set by the speed of light. In this regime plasmons display an interesting relation with tachyons, the hypothetical faster-than-light particles. While not directly observable, tachyons directly impact properties of plasmon modes. Namely, in the ``tachyon'' regime, plasmon resonances remain sharp even when the carrier collision rate $\gamma$ exceeds plasmon resonance frequency. Resonances feature a recurrent behavior as $\gamma$ increases, first broadening and then narrowing and acquiring asymmetric non-Lorentzian lineshapes with power-law tails extending into the tachyon continuum $\omega>ck$. This unusual behavior can be linked to the properties of tachyon poles located beneath $\omega>ck$ branch cuts in the complex $\omega$ plane: as $\gamma$ grows, tachyon poles approach the light cone and hybridize with plasmons. Narrow resonances persisting for $\gamma>\omega$, along with the unusual density and temperature dependence of resonance frequencies, provide clear signatures of the tachyon regime.

Magnetic and electronic phase transitions probed by nanomechanical resonators

The reduced dimensionality of two-dimensional (2D) materials results in characteristic types of magnetically and electronically ordered phases. However, only few methods are available to study this order, in particular in ultrathin insulating antiferromagnets that couple weakly to magnetic and electronic probes. Here, we demonstrate that phase transitions in thin membranes of 2D antiferromagnetic FePS3, MnPS3 and NiPS3 can be probed mechanically via the temperature-dependent resonance frequency and quality factor. The observed relation between mechanical motion and antiferromagnetic order is shown to be mediated by the specific heat and reveals a strong dependence of the Néel temperature of FePS3 on electrostatically induced strain. The methodology is not restricted to magnetic order, as we demonstrate by probing an electronic charge-density-wave phase in 2H-TaS2. It thus offers the potential to characterize phase transitions in a wide variety of materials, including those that are antiferromagnetic, insulating or so thin that conventional bulk characterization methods become unsuitable.

Lumped element kinetic inductance detectors based on two-gap MgB2 thin films

Lumped element kinetic inductance detectors (LEKIDs) are made from a single layer superconducting thin film. Because of their low noise and highly multiplexibility, LEKIDs provide a sensitive technology for the detection of millimeter and submillimeter waves. In this work, a 5-pixel 50-nm-thick MgB2 array is made. The microwave properties of the array are measured under dark conditions. We show that the loaded quality factor Q of the resonant circuit is 30 000 at 7.5 K, which is comparable to that of lower-operating-temperature (usually several hundred mK) LEKIDs made from superconductors such as Al and Nb. Moreover, the temperature dependence of resonance frequency gives the two-gap character of MgB2, Δπ (0) = 2.58 meV and Δσ (0) = 8.26 meV. The gap frequency (f = 2Δ/h) indicates that MgB2 LEKIDs have a promising application on terahertz detection.

Study of Nb and NbN Resonators at 0.1 K for Low-Noise Microwave SQUID Multiplexers

The quality factors and noise performances of superconducting resonators play an important role in microwave SQUID multiplexer (MW-MUX). Since we develop microwave SQUID multiplexer for transition edge sensor arrays, the operation temperature is around 100 mK where the effects of two level system (TLS) can be significant. In this paper, we have investigated the electrode-material or wafer dependence of noise performance of MW-MUX by characterizing four types of resonators. Although the temperature dependence of resonance frequency and the power dependence of ${{\boldsymbol{Q}}_{\boldsymbol{u}}}$ show clear difference among the materials, frequency noises which contribute the readout noise of MW-MUX are similar. Theoretical model predicts that not TLS but other loss dominates ${{\boldsymbol{Q}}_{\boldsymbol{u}}}$ in the power region suitable for the low-noise operation of our MW-MUX. Further, the estimated flux noise calculated from the measured frequency noise and the conversion coefficient from frequency to flux were 1–5 $({{{\mathbf \mu }}{{{\mathbf \Phi }}_0}/\sqrt {{{\mathbf Hz}}} })$ @ 1 Hz, 0.2–0.8 $({{{\mathbf \mu }}{{{\mathbf \Phi }}_0}/\sqrt {{{\mathbf Hz}}} })$ @ 3 kHz. These results indicate the noise of our MW-MUX has small material dependence and the compatible low noise operation to typical dc SQUIDs would be possible. Therefore, the MW-MUX with our materials would not suffer from the low frequency noise due to TLS.

Accurate MR thermometry by hyperpolarized 129 Xe.

To investigate the temperature dependence of the resonance frequency of lipid-dissolved xenon (LDX) and to assess the accuracy of LDX-based MR thermometry. The chemical shift temperature dependence of water protons, methylene protons, and LDX was measured from samples containing tissues with varying fat contents using a high-resolution NMR spectrometer. LDX results were then used to acquire relative and absolute temperature maps in vivo and the results were compared with PRF-based MR thermometry. The temperature dependence of proton resonance frequency (PRF) is strongly affected by the specific distribution of water and fat. A redistribution of water and fat compartments can reduce the apparent temperature dependence of the water chemical shift from -0.01 ppm/°C to -0.006 ppm, whereas the LDX chemical shift shows a consistent temperature dependence of -0.21 ppm/°C. The use of the methylene protons resonance frequency as internal reference improves the accuracy of LDX-based MR thermometry, but degrades that of PRF-based MR thermometry, as microscopic susceptibility gradients affected lipid and water spins differently. The LDX resonance frequency, with its higher temperature dependence, provides more accurate and precise temperature measurements, both in vitro and in vivo. More importantly, the resonance frequency of nearby methylene protons can be used to extract absolute temperature information. Magn Reson Med 78:1070-1079, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Temperature Characteristics of Magnetoelectric Effect in Bilayer Ferromagnetic-Piezoelectric Structures

Temperature characteristics of resonant magnetoelectric effect in bilayer structures consisting of langatate, lead zirconate titanate, nickel, and amorphous ferromagnetic Metglas layers have been investigated. The measurements were performed in the temperature range of 150-400 K. The influence of the ferromagnetic and piezoelectric layer’s parameters on the temperature dependence of resonant frequency and magnetoelectric coefficient αE has been demonstrated. The results can be used to develop magnetoelectric magnetic field sensors.

Concept and Model of a Metamaterial-Based Passive Wireless Temperature Sensor for Harsh Environment Applications

Wireless passive temperature sensors are receiving increasing attention due to the ever-growing need of improving energy efficient and precise monitoring of temperature in high-temperature energy conversion systems, such as gas turbines and coal-based power plants. Unfortunately, the harsh environment, such as high temperature and corrosive atmosphere present in these systems, has significantly limited the reliability and increased the costs of current solutions. Therefore, this paper presents the concept and design of a low cost, passive, and wireless temperature sensor that can withstand high temperature and harsh environments. The temperature sensor was designed following the principle of metamaterials by utilizing closed ring resonators in a dielectric ceramic matrix. The proposed wireless, passive temperature sensor behaves like an $LC$ circuit, which has a temperature-dependent resonance frequency. Full-wave electromagnetic solver Ansys Ansoft HFSS was used to validate the model and evaluate the effect of different geometry and combination of split ring resonator structures on the sensitivity and electrical sizes of the proposed sensor. The results demonstrate the feasibility of the sensor and provide guidance for future fabrication and testing.

NMR study of ferromagnetic and antiferromagnetic states of La1−xNdxMn2Si2 (x=0.35 and 0.40)

Abstract We have carried out 55Mn and 145Nd NMR measurements on re-entrant ferromagnets La1−xNdxMn2Si2 (x = 0.35, 0.4). From the bulk magnetization measurements, the compound with x = 0.35 shows ferromagnetic properties in the temperature range from T C inter = 305 to T N inter = 165 K , and antiferromagnetic properties down to ∼65 K. Then the compound orders ferromagnetically below T C Nd = 65 K . A similar temperature dependence of magnetization is observed for x = 0.4. The 55Mn NMR frequencies of both compounds fall into range 160–163 MHz at 1.4 K and are about 166 MHz at 77 K without external magnetic field. The temperature dependence of resonance frequency has been measured for x = 0.35 in the temperature from 1.4 K up to 88 K. The frequency of 55Mn is almost independent of temperature in the ferromagnetic state within experimental error, and increases abruptly around 65 K corresponding to the transition between ferromagnetic and antiferromagnetic states. The Mn magnetic moment at 1.4 K is estimated to be 2.3μB in comparison with the results of neutron diffraction measurements. Zero-field 145Nd NMR have been observed at 415 MHz at 1.4 K for both compounds. Nd magnetic moments in La1−xNdxMn2Si2 (x = 0.35, 0.4) are estimated to be 2.3μB from hyperfine field analysis.

Temperature-dependent mechanical-resonance frequencies and damping in ensembles of gallium nitride nanowires

We have measured singly clamped cantilever mechanical-resonances in ensembles of as-grown gallium nitride nanowires (GaN NWs), from 12 K to 320 K. Resonance frequencies are approximately linearly dependent on temperature near 300 K with relative shifts of 40 ± 20 ppm/K, consistent with temperature-dependent elastic moduli. Below 100 K, we find that some GaN NWs have mechanical quality factors well above 400 000, at mechanical resonance frequencies near 1 MHz. We also observe a correlation between increased amplitude of dissipation and increased temperature dependence of resonance frequencies. The microwave homodyne detection technique we use is simple, allows for the investigation of as-grown or processed NWs, and is sensitive enough to observe the thermal motion of individual NWs while providing for the simultaneous measurement of large ensembles of NW mechanical resonances.

Extraordinary terahertz transmission in superconducting subwavelength hole array

We report the extraordinary terahertz (THz) transmission through subwavelength hole array in superconducting NbN film. As the temperature drops below the superconducting transition temperature, the transmission spectra experience distinct changes. The extraordinary transmission is greatly enhanced in superconducting state due to the enhancement of surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs). We have also observed temperature-dependent resonance frequency shift, which mainly depends on the coupling between SPPs and LSPs.

Temperature Dependences of Resonance Frequency on SrBi2Nb2O9–Bi4Ti3O12 Ceramics

Temperature dependences of piezoelectric properties on mixed bismuth layer-structured ferroelectrics (BLSFs), SrBi2Nb2O9-Bi4Ti3O12 (SBN-BIT), were studied for resonator applications, aiming to have a low temperature coefficient of resonance frequency (TC-f). The SBN-BIT ceramic exhibited double dielectric anomaly peaks at 250 and 706°C from the measurement of temperature dependences of dielectric properties. We confirmed that the temperature dependences of resonance frequency also had anomaly peak at the first phase transition temperature, indicating the minimum TC-f value. In particular, the TC-f values of the (t) mode indicated −52.3 ppm/°C for the temperature range below 250°C and +4.7 ppm/°C above 250°C, which is very close to 0 ppm/°C. Moreover, it was clarified that a grain orientation was very effective for improving the TC-f values.

Temperature Dependences of Piezoelectric Properties of Grain-Oriented SrBi2Nb2O9–Bi4Ti3O12 Ceramics

Bismuth layer-structured ferroelectrics (BLSFs) have been studied for resonator applications due to its low-temperature coefficient of resonance frequency (TC-f). To control the TC-f to lower, an use of the phase transition is demonstrated in which a mixed-bismuth layer structure of SrBi2Nb2O9-Bi4Ti3O12 (SBN-BIT) is focused on as the new approach. Thus, the TC-f was tried to be controlled by using the phase transition of the SBN-BIT system. The electrical properties and the temperature dependences of the piezoelectric properties were investigated for the proposed system. The temperature dependence of resonance frequency indicated that TC-f changed from −74.8 to −14.6 ppm/°C for non oriented samples and from −42.6 to +75.8 ppm/°C for oriented samples after undergoing the phase transition.

Contribution of dielectrics to frequency and noise of NbTiN superconducting resonators

We study NbTiN resonators by measurements of the temperature dependent resonance frequency and frequency noise. Additionally, resonators are studied covered with SiOx dielectric layers of various thicknesses. The resonance frequency develops a nonmonotonic temperature dependence with increasing SiOx layer thickness. The increase in the noise is independent of the SiOx thickness, demonstrating that the noise is not dominantly related to the low temperature resonance frequency deviations.

Temperature dependence of piezoelectric properties for textured SBN ceramics

Temperature dependences of piezoelectric properties were studied for h001i textured ceramics of bismuth layer-structured ferroelectrics, SrBi(2)Nb(2)O(9) (SBN). The textured ceramics with varied orientation degrees were fabricated by templated, grain-growth method, and the temperature dependences of resonance frequency were estimated. Excellent temperature stability of resonance frequency was obtained for the 76% textured ceramics. The resonance frequency of the 76% textured specimens varied almost linearly over a wide temperature range. Therefore, the variation was slight, even in a high temperature region above 150 degrees C. Temperature stability of a quartz crystal oscillator is generally higher than that of a ceramic resonator around room temperature. The variation of resonance frequency for the 76% textured SrBi(2)Nb(2)O(9) was larger than that of oscillation frequency for a typical quartz oscillator below 150 degrees C also in this study. However, the variation of the textured SrBi(2)Nb(2)O(9) was smaller than that of the quartz oscillator over a wide temperature range from -50 to 250 degrees C. Therefore, textured SrBi(2)Nb(2)O(9) ceramics is a major candidate material for the resonators used within a wide temperature range.

A study on the microwave responses of YBCO and TBCCO thin films by coplanar resonator technique

YBa2Cu3O7(YBCO) thin films have been prepared by thermal coevaporation on LaAlO3(LAO) substrates, and Tl2Ba2CaCu2O8(TBCCO) thin films are synthesized by magnetron sputtering method on LAO substrates. The transition temperature Tc is90 K for YBCO/LAO and 104 K for TBCCO/LAO. Microwave responses of the films are studied systematically by coplanar resonator technique. Energy gaps of the films obtained are Δ0 = 1.04kBTc for YBCO films and Δ0 = 0.84kBTc for TBCCO films by analysing the temperature dependence of resonant frequencies of coplanar resonator. Penetration depth at 0 K λ0 = 198 nm for YBCO films and λ0 = 200 nm for TBCCO films could also be obtained by using the weak coupling theory and two fluid theory. Results of penetration depth and energy gap confirm the weak coupling properties of the films. In addition, microwave surface resistances Rs of YBCO/LAO and TBCCO/LAO are also investigated by analysing the quality factor and insert loss of the coplanar resonator. Surface resistance of TBCCO/LAO is less than that of YBCO/LAO, so that TBCCO/LAO films may have more potential applications.

THE EFFECT OF THE INTERACTION BETWEEN THE FILMS AND THE SUBSTRATES ON THE MICROWAVE PROPERTIES Of YBCO THIN FILMS

The microwave properties of YBa 2 Cu 3 O 7- x / LaAlO 3 (YBCO/LAO) and YBa 2 Cu 3 O 7- x / MgO (YBCO/MgO) thin films have been investigated by microstrip resonator technique. The penetration depth λ0(0 K ) and the microwave surface resistance Rs can be obtained by analyzing the experimental data of the temperature dependence of resonant frequency, unload quality factor of the microstrip resonator. The stress in the two thin films can be obtained from their XRD patterns. The result shows that the stronger stress in YBCO/LAO thing film makes it have larger microwave surface resistance at lower temperature.

Microstructure and microwave dielectric properties of BaLa 4Ti 4O 15 ceramics with template particles

BaLa 4Ti 4O 15 (BLT) ceramic has excellent microwave dielectric properties with high dielectric constant ( ɛ r) and high quality factor ( Q × f). However, BLT has the negative temperature dependence of resonant frequency ( τ f). In this study, single phase and plate-like BLT particles were prepared via a molten salt synthesis using NaCl, KCl and NaCl–KCl flux. Plate-like BLT template particles mixed with powders synthesized by solid-state reaction were uniaxially pressed and sintered. Sintered ceramics with template particles showed anisotropy in the microstructure and the crystalline phase. In the microwave dielectric properties, τ f and ɛ r increased with an increasing amount of template particles, and Q × f were nearly equal to that of specimens without template particles.