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Resonators with different designs and different resonance frequencies were fabricated on LGS. Resonators were studied at a temperature of 650°C. Annealing of LGS sensors was carried out in a furnace during 1000 hours. Dependences of the resonators behavior versus temperature were obtained. It was found that the first 100-300 hours of thermal annealing lead to the largest change in resonator properties, while further changes over the next hours are much smaller. Pt/Ti based resonators and Ir based resonators showed slow ageing trends, while Pt/Ti resonators passivated with an Al2O3 thin film with a thickness of 160 nm demonstrated steeper initial frequency changes. In spite of the obvious damage to electrodes, resonator properties remained reasonably robust to such kinds of degradation and clearly proved the possibility of long-term measurements with LGS based SAW sensor structures. The results showed that initial annealing of high temperature sensors is required to stabilize their ageing behavior. Using the XRD technique, we observed the process of oxidation of Ir and Pt electrodes of SAW-resonators during the first 100 hours of thermal annealing.

A five-component crystal of lanthanum-gallium silicate family Ca3TaGa3Si2O14 (CTGS) was grown by the Czochralski method. The CTGS crystal, like langasite crystals La3Ga5SiO14, possesses unique temperature properties and the fewer number of the Ga atoms in the unit cell makes the density much lower and, consequently, increases the velocity of acoustic wave propagation. The unit cell parameters were determined by the powder diffraction technique. The defects in the CTGS crystal structure were studied by X-ray topography which enables the visualization of growth banding characteristics of crystal grown by Czochralski method. Surface acoustic wave (SAW) propagation in the CTGS crystal was investigated by the high-resolution X-ray diffraction method. The velocities of propagation and power flow angles of SAW in the Yand X-cuts of the CTGS crystal were determined from the X-ray diffraction spectra.

A grazing incidence phase Fresnel zone plate (GIPFZP) allowing a considerable broadening of the usable spectral range in comparison with a Bragg-Fresnel zone plate is being proposed as a new type of Fresnel zone plate for X-ray focusing. A 2 μm wide image of the X-ray source was obtained by the GIPFZP.

This paper reports a scanning electron microscopy investigation of surface acoustic wave propagation in the LiNbO/sub 3/ crystals with regular domain structures. The regular domain structures in the LiNbO/sub 3/ crystals were formed by the method of the thermo-electric treatment after growth. We investigated two modes of the interaction between the surface acoustic waves and regular domain structures in the LiNbO/sub 3/ crystals: excitation of the surface acoustic waves by the curved regular domain structure, and propagation of the surface acoustic waves along and across the regular domain structures. It is shown that the regular domain structure in the first case can be used as an interdigital transducer for excitation of the surface acoustic waves through the longitudinal piezoelectric effect. In the second mode of the interaction we observed that the regular domain structure can be used as an acoustic wave-guide in the process of the propagation of the traveling surface acoustic waves along the regular domain structure. Also, we demonstrate the reflection of the surface acoustic waves from the domain walls in the process of surface acoustic wave propagation across the regular domain structure. >

X‐ray time modulation was investigated in the total external reflection conditions in the process of x‐ray diffraction on the surface of the YX cut of a LiNbO3 crystal modulated by the rectangular pulses of the surface acoustic waves. It is shown that the period and the width of the x‐ray pulses are determined by the period and the width of the rectangular surface acoustic waves pulses. Through the use of surface acoustic waves pulses it is possible to form the x‐ray pulses with special forms of x‐ray beam control, for investigation of time modulated process in microelectronic materials, and also for x‐ray/acoustic microscopy, which can be based on thermal or thermoelastically generated acoustic waves by x‐ray pulses at the depth of x‐ray penetration in investigating materials. These experiments have been made at CNRS (Grenoble, France) using a rotating copper anode.

X-ray diffraction on the surface of the YX cut of a LiNbO 3 crystal modulated by the surface acoustic wave was investigated under the total external reflection conditions. It is shown that X-ray diffraction is determined by the amplitude and by the period of the surface acoustic wave. The experimental and theoretical studies of X-ray diffraction have revealed the possibility of frabricating X-ray optical elements with space-time modulation of the diffracted radiation founded on the changes of the wavelength of the surface acoustic wave. These experiments have been made at CNRS (Grenoble, France) using a rotating copper anode.

An experiment of high-frequency X-ray beam modulation for fast digital data transfer by X-rays is presented in this paper. The modulation of the beam is performed by diffraction on surface acoustic waves whose time-structure contains already the information to be transmitted. It has been possible to connect two computers via an X-ray beam and to perform digital data transfers at a speed of a few kbits/s.

Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals.

Using a high-resolution X-Ray diffraction measurement method, the surface acoustic waves (SAW) propagation in a graphene film on the surface of a Ca3TaGa3Si2O14 (CTGS) piezoelectric crystal was investigated, where an external current was driven across the graphene film. Here we show for the first time that the application of the DC field leads to a significant enhancement of the SAW magnitude and, as a result, to amplification of the diffraction satellites. Amplification of 33.2 dB/cm for the satellite +1, and of 13.8 dB/cm for the satellite +2, at 471 MHz has been observed where the external DC voltage of +10V was applied. Amplification of SAW occurs above a DC field much smaller than that of a system using bulk semiconductor. Theoretical estimates are in reasonable agreement with our measurements and analysis of experimental data for other materials.

The formation of fields of standing surface acoustic waves (SAW) in LiNbO/sub 3/ and La/sub 3/Ga/sub 5/SiO/sub 14/ (LGS) crystals was studied by high-resolution topography method on a laboratory X-ray source. The fields of standing SAW were formed using SAW-resonator structures consisting of interdigital transducer (IDT) and reflecting gratings. The SAW amplitudes and power flow angles were measured by X-ray topography, diffraction in acoustic beam was visualized, and the SAW interaction with the crystal structure defects was studied.

This paper reports the investigation of the SAW and PSAW propagations in X-, Y- and Z-cuts of LGS crystal by scanning electron microscopy method which is very useful for qualitative and quantitative analysis of acoustic radiation wavefields in piezoelectric materials. Using the scanning electron microscopy method we visualized the diffraction patterns in the acoustic beams on the crystal surface and determined the power flow angles for SAW and PSAW.

X‐ray diffraction on the surface of the YZ cut of a LiNbO3 ferroelectric crystal modulated by standing surface acoustic waves (SAW) was investigated under the total external reflection conditions. It is shown that a metastable superlattice is formed in the near‐surface region in the process of the interaction between the incident x‐ray radiation and the ferroelectric crystal surface modulated by standing SAW. The metastable superlattice may be stored for a long time period and may be read out by x‐ray and laser radiation.

The result of X-ray diffraction study on a single crystal of the calcium-gallogermanate family Ca3TaGa3Si2O14 (CTGS) modulated by a surface acoustic wave (SAW) is presented. The power flow angle for SAW propagating along the X2 axis of the X-cut in CTGS was measured. The rocking curves for the CTGS crystal were recorded at different amplitudes of an input high frequency electric signal on interdigital transducer used to excite a SAW. Based on the data obtained, intensity dependence of diffraction satellites on the amplitude of electric signal exciting a SAW was built. Numerical simulation of the crystal rocking curves and dependence of diffraction satellite intensities on the SAW amplitude enabled the selection of a set of material constants at which the most complete coincidence of experimental and calculated results is observed.

High-resolution X-ray diffraction measurements were carried out on ZnO/Si devices under surface acoustic wave excitation and revealed some very clear satellite diffraction peaks that are obtained from the sinusoidal modulation of the near-surface region. This experiment shows that the propagation of a Rayleigh surface acoustic wave in a perfect crystal acts as a dynamical diffraction grating. The variation of the acoustic velocity has been followed across the crystal surface from the acoustic source region (beneath the ZnO film) to the far field region (not covered by the ZnO film).

The diffraction of an X-ray beam on an ultrasonic wave propagating at the surface of a crystal gives rise to diffraction satellites whose temporal structure is correlated to the one of the ultrasonic wave. Two different applications of this phenomenon are presented in this paper: By matching the temporal structure of the surface acoustic wave (SAW) with the filling mode of the storage ring, it is possible to pick or reject the incident X-ray pulses and thus to build a chopper working in the MHz range. The second application deals with binary data transfer by an X-ray beam. The experiment consists in modulating the signal fed to the acoustic transducer with a signal carrying digital data, which is a way of transmitting this information into the X-ray beam satellite.

The diffraction of an X-ray beam on an ultrasonic wave propagating at the surface of a crystal gives rise to diffraction satellites whose temporal structure is correlated to that of the ultrasonic wave. By matching the temporal structure of the surface acoustic wave with the filling mode of the storage ring, it is possible to select or reject the incident X-ray pulses. A few examples of the performance of this MHz-range chopper for various filling modes are presented.

X-ray diffraction on the crystal La3Ga5.5Ta0.5O14 modulated by surface acoustic waves (SAW) and pseudo-surface acoustic waves (PSAW) with wavelength of Λ=8 μm was studied using a double axis X-ray diffractometer at the BESSY II synchrotron radiation source. The propagation of SAW and PSAW leads to sinusoidal modulation of the crystal lattice and gives rise to diffraction satellites on the rocking curve, with the intensity and angular divergence between the diffraction satellites depending on the wavelength and amplitude of the crystal lattice acoustic modulation. The analysis of diffraction spectra enables the determination of the amplitude and acoustic wavelengths, and power flow angles of acoustic energy propagation. The investigation of acoustic wave fields showed that PSAW is a flowing back wave which propagates at an angle to the crystal surface.

This paper reports a scanning electron microscopy visualization of surface acoustic waves in single- and poly-domains LiNbO 3 crystals. This SEM method is very useful to visualize traveling and standing surface acoustic waves in SAW-devices and to observe the interaction between SAWs and defects on crystal surfaces. Furthermore, we investigated the interaction between SAWs and regular domain structures in LiNbO 3 crystals

X-ray diffraction on the YZ cut of a LiNbO 3 crystal modulated by surface acoustic waves was investigated under the total external reflection conditions. It is shown that the characteristics of the diffracted beam are determined by the amplitude and by the period of the surface acoustic waves. This experimental study has revealed the possibility of fabricating optical instruments for space-time modulation of X-ray diffracted radiations based on the control of the wavelength of the surface acoustic waves

X-ray Bragg diffraction on an acoustically modulated La3Ga5SiO14 crystal (langasite, LGS) was studied in the saggital geometry where a surface acoustic wave (SAW) serves as diffraction grating of normal incidence. A set of parabolic compound Be refracting lenses was used to focus x-ray radiation in order to obtain good angular and spatial resolution of diffraction satellites. X-ray diffraction spectra analysis provided information on the acoustic properties of the LGS crystal and enabled the determination of SAW amplitudes and wavelengths.

The x-ray beam induced current method (XBIC) is realized on the laboratory x-ray source using the polycapillary x-ray optics. It is shown that rather good images of grain boundaries in Si can be obtained by this method. The parameters of x-ray beam are estimated by the simulation of Schottky diode image. A good correlation between the experimental and calculated grain boundary XBIC contrast is obtained. The possibilities of laboratory source based XBIC method are estimated.

A ferroelectric domain structure formed in the X cut of a LiNbO3 crystal by aftergrowth thermoelectrical treatment was studied by x-ray diffraction and topography methods. An external electric field applied along the X axis to the crystal causes shift deformations due to the reverse piezoelectric effect, which permits visualization of domain structures in the X cut of a LiNbO3 crystal. Oppositely directed inclinations of reflecting planes in adjacent domains, caused by the reverse piezoelectric effect, give rise to different diffraction angles in neighboring domains and make visualization of domain structure possible.

Regular domain structures formed in ferroelectric LiNbO3 and LiTaO3 crystals by the aftergrowth thermoelectrical treatment technique were studied by high-resolution x-ray diffraction and topography under an external electric field applied to the crystals. The application of an external electric field to the crystal causes longitudinal and shift deformations due to the reverse piezoelectric effect and, as a result, inverse changes in the Bragg angle values in adjacent domains. The changes in the Bragg angle values lead to an increase in the x-ray topographic contrast of the domain structure images and allow the direction of the polar and piezoelectrically active axis in adjacent domains to be unambiguously determined. In addition, it was shown that the x-ray diffraction technique can be used to study the behavior of elastic deformations near domain boundaries under an external electric field applied to crystals.

The x-ray standing wave technique has been used to characterize a multilayer mirror modulated by surface acoustic waves. Upon sinusoidal modulation of a multilayer by surface acoustic waves, fields of x-ray standing waves are found to form around the Bragg conditions and at the angular positions of the rocking curve diffraction satellites. It is shown that the angular position of the diffraction peaks in the rocking curve and the amplitude of x-ray standing waves are determined by the wavelength and the amplitude of the surface acoustic waves, respectively.

X-ray diffraction spectra at different x-ray energies from a Si crystal subjected to a deformation produced by surface acoustic wave propagation have been modeled using the general framework of dynamical diffraction theory. The simulations have been successfully compared with the corresponding experimental results confirming the accuracy of the elastic model describing the acoustic wave fields inside the crystal.

This letter reports a scanning electron microscopy investigation of surface acoustic wave diffraction on the zigzag domain wall in a Gd2(MoO4)3 crystal. The zigzag domain wall with ∼80 μm period was formed in a Gd2(MoO4)3 crystal by applying the external mechanical stress. It is shown that the surface acoustic wave diffracts on the zigzag domain wall in a ferroelastic Gd2(MoO4)3 crystal.

This letter reports on a scanning electron microscopy study of reflection of surface acoustic waves on the domain walls in a LiNbO3 crystal. The regular domain structure with ∼5‐mm period was formed in a LiNbO3 crystal by the method of aftergrowth thermoelectrical treatment. It is shown that the regular domain structure reflects surface acoustic waves on the domain walls in a ferroelectric LiNbO3 crystal.

This letter reports a scanning electron microscope study of excitation of surface acoustic waves by the regular domain structures in LiNbO3 crystals. The regular domain structures in LiNbO3 crystals were formed by the method of aftergrowth thermoelectrical treatment. It is shown that the regular domain structures excite surface acoustic waves by the piezoelectric effect. In this case, the wavelength of the surface acoustic waves is determined by the period of the regular domain structure. These experiments have been made at CNRS (Grenoble, France) using a scanning electron microscope JSM‐840.

In present paper we report the fabrication process of a high-temperature SAW-sensor based on a langasite crystal. Interdigital transducers of the SAW-resonator structures were fabricated from Ir which was evaporated using magnetron sputtering technique. The SAW-sensors were designed with different coefficient of metallization of an IDT, which strongly influences on the value of the SAW velocity and resonance excitation frequency, respectively. The process of the SAW excitation was investigated using high-resolution X-ray diffraction technique

X-ray diffraction on surface acoustic waves with tunable wavelength provides a way to perform beam scannings. 1D and 2D space scannings of x-ray beams by this method are presented. The feasibility of a purely optical method to perform scanning x-ray imaging without any mechanical movement is discussed.

We directly measured SHG and DFG phase-matching angles of the Langatate LGT until 6 µm. We found a nonlinear coefficient d11 = 0.61 pm/V, and we identified LGT as a promising crystal for an OPO pumped around 800 nm.

X-ray Bragg diffraction on the X, Y, and (011) cuts of a langasite crystal (La/sub 3/Ga/sub 5/SiO/sub 14/, LGS) modulated by a Rayleigh surface acoustic wave (SAW) has been studied using a high-resolution X-ray topography method. This X-ray topography technique was used for direct imaging of the standing SAW in LGS, to measure the SAW amplitudes and power flow angles, to visualize the diffraction patterns in acoustic beams, and to study the process of the SAW interaction with crystal structure defects.

Results of experimental studies using grazing incidence phase Fresnel zone plates for two-dimensional X-ray focusing in the Kirkpatrick-Baez scheme and creation of an X-ray microprobe are presented. The efficiency of incident radiation focusing by this probe is estimated. Possible applications of the such an optics scheme for X-ray diffraction investigations are considered.

International audience; We demonstrate phase-matched difference frequency generation in the emerging nonlinear crystal La3Ga5.5Ta0.5O14. Tunable wavelengths between 1.4 and 4.7 μm are generated by using femtosecond sources. We also report on the measurements of the optical damage threshold in the femtosecond regime and on the nonlinear refractive index n2.