An Analysis of the Water-to-Ice Phase Transition Using Acoustic Plate Waves

Kringle L., Thornley W.A., Kay B.D., Kimmel G.A.

Supercooled water structures Water displays a number of anomalous properties that are further enhanced in its supercooled state, but experimental studies at ambient pressure must obtain data before the onset of rapid crystallization at temperatures below ∼240 kelvin. Kringle et al. obtained infrared spectra of supercooled water films at temperatures between 135 and 235 kelvin that formed for a few nanoseconds by ultrafast heating and cooling. Supercooled water thermally equilibrates before crystallization above 170 kelvin, and over the range of temperatures studied, the structure of water was shown to be a linear combination of a high-density and a low-density liquid. Science , this issue p. 1490

Wang W., Yin Y., Jia Y., Liu M., Liang Y., Zhang Y., Lu M.

This work addresses the theoretical and experimental investigations of a Love wave based device employing waveguide structure of SiO2/36° YX-LiTaO3 for sensing icing process. The mass loading effect induced by the icing process modulates the acoustic wave propagation, and corresponding changes in device frequency can be collected to evaluate the icing process. The waveguide structure confines the acoustic wave energy into SiO2 thin-film, which contributes well to the improvement of the mass loading sensitivity. The corresponding sensing mechanism was analyzed by solving the acoustic propagation equations in layered structure. The sensing device patterned by delay-line on 36° YX-LiTaO3 substrate with SiO2 guiding layer was photolithographically developed as the sensor element, and characterized by using the high-low temperature chamber. The icing process was simulated by dropping appropriate water on top of the device surface. Very clear and fast frequency response was observed from the proposed sensing device in the icing process, and also, the influence of SiO2 guiding layer thickness on sensor response was also investigated.

Chakraborty S., Kahan T.F.

Sea ice presents a complex reaction medium containing poorly understood distributions of solutes, ice, and sometimes liquid brine. We studied the three-dimensional distribution of liquid brine and ...

Anisimkin V.I., Voronova N.V.

The article studies the spectrum of acoustic oscillations generated by interdigital transducers in a plate made from a LiNbO3 piezocrystal with a thickness on the order of the acoustic wavelength. It is shown that, along with zeroth and higher-order modes, this spectrum also contains odd harmonics of the same modes. Unlike surface waves without dispersion, the harmonic frequencies of normal waves are not exact multiples of their fundamental frequency due to velocity dispersion, and the harmonic amplitudes can differ from the wave amplitudes at fundamental frequencies due to the dispersion of the electromechanical coupling coefficient. The temperature sensitivities of modes and harmonics differ from each other and vary with the fluid loading of the surface.

Wang Y., Li F., Fang W., Li Y., Sun C., Men Z.

The structure of liquid water is strongly influenced by Si quantum dots (Si QDs). We employed Raman spectroscopy to investigate how Si QDs affect the icing point of water. In contrast with the Raman spectra of pure water, Raman spectra of Si QDs water solutions exhibit some distinct characteristic features. The Raman spectra present that liquid- ice Ih phase transition takes place at 264 and 266 K in 5 and 2 nm Si QDs solutions respectively, which is higher than that of pure water (257 K). These phenomena are contributed to the electric field generated by Si QDs and the hydrogen bonds formed between silanol groups and water molecules. The results can open the way to understand the interaction between water molecules and quantum dots in some environments.

Bovo L., Rouleau C.M., Prabhakaran D., Bramwell S.T.

Vertex models are an important class of statistical mechanical system that admit exact solutions and exotic physics. Applications include water ice, ferro- and antiferro-electrics, spin ice and artificial spin ice. Here we show that it is possible to engineer spin ice films with atomic-layer precision down to the monolayer limit. Specific heat measurements show that these films, which have a fundamentally different symmetry to bulk spin ice, realise systems close to the two-dimensional F-model, with exotic phase transitions on topologically-constrained configurational manifolds. Our results show how spin ice thin films can release the celebrated Pauling entropy of spin ice without an anomaly in the specific heat. They also significantly expand the class of vertex models available to experiment. Magnetic spin ice compounds are described by vertex models, which have been intensively studied for their exotic properties. Bovo et al. show thin films of Dy2Ti2O7 have structures distinct from bulk crystals and come close to realising the two-dimensional F-model, which has an unusual ordering transition in the Berezinskii–Kosterlitz–Thouless class.

Slater B., Michaelides A.

Frozen water has a quasi-liquid layer at its surface that exists even well below the bulk melting temperature; the formation of this layer is termed premelting. The nature of the premelted surface layer, its structure, thickness and how the layer changes with temperature have been debated for over 160 years, since Faraday first postulated the idea of a quasi-liquid layer on ice. Here, we briefly review current opinions and evidence on premelting at ice surfaces, gathering data from experiments and computer simulations. In particular, spectroscopy, microscopy and simulation have recently made important contributions to our understanding of this field. The identification of premelting inhomogeneities, in which portions of the surface are quasi-liquid-like and other parts of the surface are decorated with liquid droplets, is an intriguing recent development. Untangling the interplay of surface structure, supersaturation and surface defects is currently a major challenge. Similarly, understanding the coupling of surface structure with reactivity at the surface and crystal growth is a pressing problem in understanding the behaviour and formation of ice on Earth. A quasi-liquid layer on the surface of ice makes it slippery even below the bulk melting temperature. The nature of this premelted layer has long been debated, and this Review gathers experimental and theoretical data and discusses opinions and evidence on premelting at ice surfaces.

Wang Y., Wang T., Liu J., Wang Y., Laude V.

We investigate experimentally Lamb wave propagation in coupled-resonator elastic waveguides (CREWs) formed by a chain of cavities in a two-dimensional phononic crystal slab with cross holes. Wide complete bandgaps, extending from 53 to 88 kHz, are first measured in a finite phononic crystal slab sample. A straight waveguide and a wave splitting circuit with 90° bends are then designed, fabricated and measured. Elastic Lamb waves are excited by a piezoelectric patch attached to one side of the phononic slab and detected using a scanning vibrometer. Strongly confined guiding and splitting at waveguide junctions are clearly observed for several guided waves. Numerical simulations are found to be in excellent agreement with experimental results and allow for the identification of the involved resonant cavity modes. The influence on the dispersion of guided waves of the slab thickness and of the hole length is also investigated. The results have implications for the design of innovative phononic devices with strong confinement and tailorable dispersion.

Kuznetsova I.E., Anisimkin V.I., Kolesov V.V., Kashin V.V., Osipenko V.A., Gubin S.P., Tkachev S.V., Verona E., Sun S., Kuznetsova A.S.

The measurement of humidity is very important for air control in ambient, industry, cars, houses, closed apartments, museums, atomic power stations, etc. In the present work the theoretical analysis of the surface acoustic wave propagation in “graphen oxide (GO) film/ZnO film/Si substrate” layered structure has been performed. The change of GO film conductivity due to humidity has been taken into account during the calculations. Based on the obtained results an improved microwave acoustic humidity sensor has been developed. The sensor has enhanced sensitivity of about 91 kHz/% and linear response vs relative humidity in the range 20–98%RH. It is based on the mode belonging to Sezawa wave family that is shown to be more sensitive towards electric conductivity variations in GO film produced by adsorbed water molecules than the Rayleigh counterpart.

Neumeier J.J.

Published elastic constant data for H2O ice in the Ih phase are compiled and evaluated. Fits of the five elastic constants for 50 ≤ T/K ≤ 273 are conducted to yield a reliable and convenient source for elastic constant values. Various elastic properties can be calculated from the elastic constants obtained herein. The elastic constants are used to determine the adiabatic bulk modulus BS for the same temperature range with an estimated uncertainty of less than 1.3%. Fitting those data yields an equation for BS that is extrapolated to provide values for 0 ≤ T/K < 50. The adiabatic compressibility KS, isothermal bulk modulus BT, and isothermal compressibility KT are calculated from BS. Comparisons are made to published data.Published elastic constant data for H2O ice in the Ih phase are compiled and evaluated. Fits of the five elastic constants for 50 ≤ T/K ≤ 273 are conducted to yield a reliable and convenient source for elastic constant values. Various elastic properties can be calculated from the elastic constants obtained herein. The elastic constants are used to determine the adiabatic bulk modulus BS for the same temperature range with an estimated uncertainty of less than 1.3%. Fitting those data yields an equation for BS that is extrapolated to provide values for 0 ≤ T/K < 50. The adiabatic compressibility KS, isothermal bulk modulus BT, and isothermal compressibility KT are calculated from BS. Comparisons are made to published data.

Myint P.C., Belof J.L.

Understanding the behavior of materials at extreme pressures is a central issue in fields like aerodynamics, astronomy, and geology, as well as for advancing technological grand challenges such as inertial confinement fusion. Dynamic compression experiments to probe high-pressure states often encounter rapid phase transitions that may cause the materials to behave in unexpected ways, and understanding the kinetics of these phase transitions remains an area of great interest. In this review, we examine experimental and theoretical/computational efforts to study the freezing kinetics of water to a high-pressure solid phase known as ice VII. We first present a detailed analysis of dynamic compression experiments in which water has been observed to freeze on sub-microsecond time scales to ice VII. This is followed by a discussion of the limitations of currently available molecular and continuum simulation methods in modeling these experiments. We then describe how our phase transition kinetics models, which are based on classical nucleation theory, provide a more physics-based framework that overcomes some of these limitations. Finally, we give suggestions on future experimental and modeling work on the liquid-ice VII transition, including an outline of the development of a predictive multiscale model in which molecular and continuum simulations are intimately coupled.

Caliendo C., Castro F.

Chen Z., Fan L., Zhang S., Zhang H.

In an ultrasonic sensor, the electromechanical coupling coefficient, sensitivities related to the mass load and conductivity variation, insert loss and minimum detectable mass are important parameters determining the performance of the sensor, while it is challenging to optimize the abovementioned five parameters simultaneously. In this paper, we show that the multi-mode characteristic of Lamb wave provides possibilities to improve the performance of ultrasonic sensors by simultaneously considering the five parameters. According to the simulated results, piezoelectric films, relative thicknesses of films and substrates, structures of interdigital transducers, operating wavelengths and frequencies are optimized based on properly selected operating modes of Lamb wave. Then, high performance of Lamb wave sensors can be realized, in which high electromechanical coupling coefficients, mass sensitivities and conductivity sensitivities in addition to low insert losses and minimum detectable masses are simultaneously achieved.

Zhu X., Yuan Q., Zhao Y.

We show by using molecular dynamics simulations that a water overlayer on charged graphene experiences first-order ice-to-liquid (electromelting), and then liquid-to-ice (electrofreezing) phase transitions with the increase of the charge value. Corresponding to the ice-liquid-ice transition, the variations of the order parameters indicate an order-disorder-order transition. The key to this novel phenomenon is the surface charge induced change of the orientations of water dipoles, which leads to the change of the water-water interactions from being attractive to repulsive at a critical charge value qc. To further uncover how the orientations of water dipoles influence the interaction strength between water molecules, a theoretical model considering both the Coulomb and van der Waals interactions is established. The results show that with the increase of the charge value, the interaction strength between water molecules decreases below qc, then increases above qc. These two inverse processes lead to electromelting and electrofreezing, respectively. Combining this model with the Eyring equation, the diffusion coefficient is obtained, the variation of which is in qualitative agreement with the simulation results. Our findings not only expand our knowledge of the graphene-water interface, but related analyses could also help recognize the controversial role of the surface charge or electric field in promoting phase transitions of water.

Anisimkin V.I., Voronova N.V., Zemlyanitsyn M.A., Kuznetsova I.E., Pyataikin I.I.

Excitation and propagation of the I.V. Anisimkin and Lamb acoustic plate modes of various orders n has been experimentally investigated using, as an example, rotated 128° YX LiNbO3 piezoelectric plates. It is shown that (1) an increase in the number of fingers of the interdigital transducers improves the frequency resolution of the neighboring modes with close velocities, (2) the use of aluminum as a finger material reduces the ripple of the mode amplitude-frequency characteristics (AFC) n as compared to that in the case of gold fingers, and (3) the propagation loss increases with the distance and mode number n. It has been found that group velocities (v g) n and phase velocities (v p) n of the modes excited and received on the same surface of the plate do not change with distance starting, at least, from a 25-wavelength distance from the radiator. It has been established that, if the electrically conducting fluid is deposited on the opposite side of the plate, the shape of the (AFC) n , central frequency f n , and the phase characteristics of certain modes undergo changes that depend on whether the areas under the transducers are also covered with the fluid and on the distance between the transducers. No noticeable reflection of the modes from the plate edges has been recorded.

Ong H.L., Ji Z., Haworth L., Guo Y., del Moral J., Jacob S., Borras A., Gonzalez‐Elipe A.R., Zhang J., Zhou J., McHale G., Fu Y.

Fogging, icing, or frosting on optical lenses, optics/photonics, windshields, vehicle/airplane windows, and solar panel surfaces have often shown serious safety concerns with hazardous conditions and impaired sight. Various active techniques, such as resistive heating, and passive techniques, such as icephobic treatments, are widely employed for their prevention and elimination. However, these methods are not always suitable, effective, or efficient. This review provides a comprehensive overview of the fundamentals and recent advances of transparent thin‐film surface acoustic wave (SAW) technologies on glass substrates for monitoring and prevention/elimination of fogging, frosting, and icing. Key challenges related to fogging and icing on glass substrates are discussed, along with fundamental mechanisms that establish thin‐film SAWs as optimal solution for these issues. Various types of thin‐film acoustic wave technologies are discussed, including recent wearable and flexible SAW devices integrated onto glass substrates for expanding future applications. The focus of this review is on the principles and strategies for hybrid or integrated de‐fogging/de‐icing and sensing/monitoring functions. Finally, critical issues and future outlooks for thin‐film‐based SAW technology on glass substrates in industry applications are presented.

Smirnov A., Anisimkin V., Ageykin N., Datsuk E., Kuznetsova I.

An important technical task is to develop methods for recording the phase transitions of water to ice. At present, many sensors based on various types of acoustic waves are suggested for solving this challenge. This paper focuses on the theoretical and experimental study of the effect of water-to-ice phase transition on the properties of Lamb and quasi shear horizontal (QSH) acoustic waves of a higher order propagating in different directions in piezoelectric plates with strong anisotropy. Y-cut LiNbO3, 128Y-cut LiNbO3, and 36Y-cut LiTaO3 plates with a thickness of 500 μm and 350 μm were used as piezoelectric substrates. It was shown that the amplitude of the waves under study can decrease, increase, or remain relatively stable due to the water-to-ice phase transition, depending on the propagation direction and mode order. The greatest decrease in amplitude (42.1 dB) due to glaciation occurred for Lamb waves with a frequency of 40.53 MHz and propagating in the YX+30° LiNbO3 plate. The smallest change in the amplitude (0.9 dB) due to glaciation was observed for QSH waves at 56.5 MHz propagating in the YX+60° LiNbO3 plate. Additionally, it was also found that, in the YX+30° LiNbO3 plate, the water-to-ice transition results in the complete absorption of all acoustic waves within the specified frequency range (10–60 MHz), with the exception of one. The phase velocities, electromechanical coupling coefficients, elastic polarizations, and attenuation of the waves under study were calculated. The structures “air–piezoelectric plate–air”, “air–piezoelectric plate–liquid”, and “air–piezoelectric plate–ice” were considered. The results obtained can be used to develop methods for detecting ice formation and measuring its parameters.

Pandey S., del Moral J., Jacob S., Montes L., Gil‐Rostra J., Frechilla A., Karimzadeh A., Rico V.J., Kantar R., Kandelin N., López‐Santos C., Koivuluoto H., Angurel L., Winkler A., Borrás A., et. al.

Acoustic waves (AW) have recently emerged as an energy‐efficient ice‐removal procedure compatible with functional and industrial‐relevant substrates. However, critical aspects at fundamental and experimental levels have yet to be disclosed to optimize their operational conditions. Identifying the processes and mechanisms by which different types of AWs induce de‐icing are some of these issues. Herein, using model LiNbO3 systems and two types of interdigitated transducers, the e‐icing and anti‐icing efficiencies and mechanisms driven by Rayleigh surface acoustic waves (R‐SAW) and Lamb waves with 120 and 510 μm wavelengths, respectively, are analyzed. Through the experimental analysis of de‐icing and active anti‐icing processes and the finite element simulation of the AW generation, propagation, and interaction with small ice aggregates, it is disclosed that Lamb waves are more favorable than R‐SAWs to induce de‐icing and/or prevent the freezing of small ice droplets. Prospects for applications of this study are supported by proof of concept experiments, including de‐icing in an icing wind tunnel, demonstrating that Lamb waves can efficiently remove ice layers covering large LN substrates. Results indicate that the de‐icing mechanism may differ for Lamb waves or R‐SAWs and that the wavelength must be considered as an important parameter for controlling the efficiency.

Rekuviene R., Saeidiharzand S., Mažeika L., Samaitis V., Jankauskas A., Sadaghiani A.K., Gharib G., Muganlı Z., Koşar A.

Icing introduces significant damage to aviation and renewable energy installations. High voltage transmission lines, wind turbine blades, and airplane and helicopter blades often suffer from icing phenomenon, which causes severe energy losses and impairs aerodynamic performance. There are a significant number of different studies proposing de-icing and anti-icing techniques. It is noticeable that the vast majority of these methods are oriented towards a particular area, and their adaptation to other areas is problematic. These methods often use various technologies, have different specifications, and sometimes lack clear interpretation of efficiency. This review presents a comprehensive overview of the most common de-icing and anti-icing technologies and identifies their benefits and limitations. Two major groups of de-icing and anti-icing methods were covered: passive and active methods. Among the passive methods, chemical methods, biochemical methods, and paint coatings, which either weaken the ice adhesion or shift the freezing point of a surface, were discussed in detail. The reviewed active methods include the hot air method, resistive method, infrared method, and microwave heaters, as well as the expulsive method, pneumatic method, water jet method, and high-power ultrasonic de-icing as mechanical methods. Passive methods lead to a limited performance under severe freezing, are often too expensive to cover large surfaces, and their effectiveness degrades over time, while active techniques cause high energy consumption and require intervention in the structure's design, and they are also more effective and provide a faster response, especially during severe freezing. It can be noted that various parameters impact the effectiveness of de-icing and anti-icing techniques for different applications. These parameters are limited to physical and chemical properties of the aimed engineering surfaces, environmental factors, severity of icing (clear, mixed, rime, crystal, etc.), size of the affected area and functionality of the whole energy system and should be thoroughly investigated and be taken into consideration in order to achieve a feasible, effective and economical de-icing or anti-icing approach for each application.

Smirnov A., Anisimkin V., Voronova N., Kashin V., Kuznetsova I.

The detection of the liquid-to-ice transition is an important challenge for many applications. In this paper, a method for multi-parameter characterization of the liquid-to-ice phase transition is proposed and tested. The method is based on the fundamental properties of bulk acoustic waves (BAWs). BAWs with shear vertical (SV) or shear horizontal (SH) polarization cannot propagate in liquids, only in solids such as ice. BAWs with longitudinal (L) polarization, however, can propagate in both liquids and solids, but with different velocities and attenuations. Velocities and attenuations for L-BAWs and SV-BAWs are measured in ice using parameters such as time delay and wave amplitude at a frequency range of 1–37 MHz. Based on these measurements, relevant parameters for Rayleigh surface acoustic waves and Poisson’s modulus for ice are determined. The homogeneity of the ice sample is also detected along its length. A dual sensor has been developed and tested to analyze two-phase transitions in two liquids simultaneously. Distilled water and a 0.9% solution of NaCl in water were used as examples.

Liang S., Treeby B.E., Martin E.

Schulmeyer P., Weihnacht M., Schmidt H.

Ice accumulation on infrastructure poses severe safety risks and economic losses, necessitating effective detection and monitoring solutions. This study introduces a novel approach employing surface acoustic wave (SAW) sensors, known for their small size, wireless operation, energy self-sufficiency, and retrofit capability. Utilizing a SAW dual-mode delay line device on a 64°-rotated Y-cut lithium niobate substrate, we demonstrate a solution for combined ice detection and temperature measurement. In addition to the shear-horizontal polarized leaky SAW, our findings reveal an electrically excitable Rayleigh-type wave in the X+90° direction on the same cut. Experimental results in a temperature chamber confirm capability for reliable differentiation between liquid water and ice loading and simultaneous temperature measurements. This research presents a promising advancement in addressing safety concerns and economic losses associated with ice accretion.

Karimzadeh A., Weissker U., del Moral J., Winkler A., Borrás A., González‐Elipe A.R., Jacob S.

AbstractMicroacoustic wave devices are essential components in the radio frequency (RF) electronics and microelectromechanical systems (MEMS) industry with increasing impact in various sensing and actuation applications. Reliable and smart operation of acoustic wave devices at low costs will cause a crucial advancement. Herein, this study presents the enablement of temperature and mechanical sensing capabilities in a Rayleigh‐mode standing surface acoustic wave (sSAW) chip device by harnessing an acoustic shear‐thickness dominant wave (SD) using the same set of electrodes. Most importantly, this mode is excited by switching the polarity of the sSAW transducer electrodes by simple electronics, allowing for direct and inexpensive compatibility with an existing setup. The method in the emergent topic of surface de‐icing is validated by continuously monitoring temperature and liquid–solid water phase changes using the SD mode, and on‐demand Rayleigh‐wave deicing with a negligible energy cost. The flexibility for adapting the system to different scenarios, and loads and the potential for scalability opens the path to impact in lab‐on‐a‐chip, internet of things (IoT) technology, and sectors requiring autonomous acoustic wave actuators.

Sibilia S., Tari L., Bertocchi F., Chiodini S., Maffucci A.

This paper investigates the possibility of realizing ice sensors based on the electrical response of thin strips made from pressed graphene nano-platelets. The novelty of this work resides in the use of the same graphene strips that can act as heating elements via the Joule effect, thus opening the route for a combined device able to both detect and remove ice. A planar capacitive sensor is designed and fabricated, in which the graphene strip acts as one of the armatures. The sensing principle is based on the high sensitivity of the planar capacitor to the change in electrical permittivity in the presence of ice, as shown in the experimental case study discussed here, can also be interpreted by means of a simple circuit and electromagnetic model. The properties of the sensor are analyzed, and the frequency range for its use as an ice detector has been established.

Ageikin N.A., Anisimkin V.I., Voronova N.V., Smirnov A.V.

The dependence of radiation losses into a liquid on the value of the displacement component U_3 normal to the plate on the surface of a piezoelectric plate was experimentally studied for Lamb waves of various orders. Waves whose phase velocity V_n in the plate are considered greater than the velocity of the longitudinal volumetric acoustic wave in the liquid V_l. It is shown that at small values of U3 there is no radiation into the liquid and the magnitude of radiation losses is close to zero even at V_n V_l; at large values of U_3, the magnitude of radiation losses is large and for Lamb waves in the YZ-LiNbO3 plate with a thickness normalized to the wavelength of 1.75 and frequency 16.97 MHz it reaches a value of 4 dB/mm, comparable to the radiative losses of surface acoustic waves in the same material.

Ageikin N.A., Anisimkin V.I., Voronova N.V., Smirnov A.V.

The dependence of radiation losses in a liquid on the value of displacement component U3 normal to the plate on the surface of a piezoelectric plate for Lamb waves of various orders has been experimentally investigated. The waves whose phase velocity Vn in the plate is greater than velocity Vl of the longitudinal volumetric acoustic wave in the liquid are considered. It is shown that at low values of U3, there is no radiation into the liquid and the value of radiation losses is close to zero even at Vn > Vl, at high values of U3, the value of radiation losses is large and for Lamb waves in the YZ–LiNbO3 plate with a normalized wavelength thickness of 1.75 and a frequency of 16.97 MHz, it reaches a value of 4 dB/mm, comparable to the radiation losses of surface acoustic waves in the same material.

Zhou Y., Zhou W., Ren Z., Zhang Y., Gong H., shen C., Chen R., Albert J.

In-situ monitoring of refractive index changes during a liquid-solid phase transition is achieved by measurement of the transmission spectrum from a single tilted fiber Bragg grating immersed in water. Differential wavelength shifts of multiple mode resonances are used to eliminate cross-talk from temperature, throughout the phase transition, and from strains occurring after solidification. The measured sudden shift of refractive index at the phase transition is shown to be consistent with the expected difference from water to ice, in spite of the observed onset of compressive strain on the fiber by the frozen water. Beyond the obvious application to research on the dynamics of liquid-solid phase transitions, this work demonstrates the multiparameter measurement capabilities of multiresonant gratings.

del Moral J., Montes L., Rico‐Gavira V.J., López‐Santos C., Jacob S., Oliva‐Ramirez M., Gil‐Rostra J., Fakhfouri A., Pandey S., Gonzalez del Val M., Mora J., García‐Gallego P., Ibáñez‐Ibáñez P.F., Rodríguez‐Valverde M.A., Winkler A., et. al.

Smirnov A., Anisimkin V., Voronova N., Shamsutdinova E., Li P., Ezzin H., Qian Z., Ma T., Kuznetsova I.

Using acoustic wave modes propagation in piezoelectric plates loaded with conductive liquids, peculiarities of the mode-liquid acoustoelectric interaction are studied. It is found that (i) in contrast to bulk and surface acoustic waves propagating in piezoelectric semiconductors, the acoustoelectric attenuation of the modes is not symmetric in respect to its maximum, (ii) a large increase in attenuation may be accompanied by a small decrease in phase velocity and vice versa, (iii) the peculiarities are valid for “pure” (without beam steering) and “not pure” (with beam steering) modes, as well as for modes of different orders and polarizations, and (iv) conductivity of test liquid increases electromagnetic leakage between input and output transducers, affecting results of the measurements. To decrease the leakage, the liquid should be localized between transducers, outside the zone over them. If so, the mode sensitivity may be as large as 8.6 dB/(S/m) for amplitude and 107°/(S/m) for phase. However, because of comparable cross-sensitivity towards viscosity and dielectric permittivity, modes with selective detection of liquid conductivity are not found.

Anisimkin V.I., Voronova N.V.

• Lamb waves with elliptic polarization oriented parallel to the plate faces exist in crystal plates. • Particular polarization is maintained at any depth from free faces, for wide range of plate thickness. • The new waves are promissing for sensing liquid viscosity and liquid-to-ice phase transitions. Using quartz plates as an example existance of the new modification of the Lamb waves is demonstrated. The waves have small vertical displacement, large shear-horizontal and longitudinal components, and elliptic polarization which is oriented parallel to the plate faces. Numerical calculations of the surface displacements and depth profiles show the particular polarization is maintained at any depth from free faces and for all plate thickness in the range h/λ = 0–1.7 (h - thickness, λ - wave length). Results of the measurements accomplished for four new modes and three plate thickness h/λ confirm that radiation of the waves into adjucent liquid (which is proportional to vertical displacement) is small, while viscoelestic loss of the same the waves (which is proportional to in-plane components) is large. This property makes the modified waves suitable for sensing liquids and ices. In particular, responses of the waves towards liquid viscosity and water-to-ice transformation are larger than those are for common Lamb waves approaching 27 and 50 dB, respectively, at about 30 MHz, 1500 cP, and 10 mm propagation path.