Potassium Tantalum Niobate Research Articles

Measurement of space charge density distributions and dielectric resonance enhancement of beam deflection properties of KTN crystal

In recent years, potassium tantalum niobate (KTN) electro-optical deflection devices have gained considerable attention because of their notable advantages, such as large deflection angles, low operational voltage requirements, and compact dimensions. This study uses the phase-shifted interferometric optical path to characterize the influence of direct current (DC) voltage on charge density. An interferogram is acquired using the four-step phase-shifting technique, enabling the calculation of phase delays and deducing the variation in charge density. Experimental results demonstrate that the charge density near the cathode increases with an increase in DC voltage. Subsequently, we utilize the frequency dependence of the dielectric constant of the KTN crystal on the electric field. The dielectric constant can be enhanced when the characteristic frequency of the motion of the polar nanoscale region matches the frequency of the electric field. This field-induced enhancement effect improves the beam deflection performance of the KTN crystal. Application requirements in the field of high-speed random scanning can be realized through the mechanism of the KTN crystal co-acting with DC and alternating current electric fields.

Characterization of temperature-dependent superlattice in Cu:KTN crystal

In this study, we grew CuO doped potassium tantalum niobate (Cu:KTN) crystals with a uniform superlattice structure by the off-center top-seeded solution growth (TSSG) method. The process of crystal superlattice structure formation was observed under a polarizing microscope at variable temperatures. It was found that the formation of the superlattice structure in the crystal was closely related to the formation process of the domain structure in the crystal. The 90° domain structure in the crystal promoted the formation of the superlattice structure in the crystal. The purpose of the formation of the superlattice structure is to enable the crystal to reach a more stable state. The clear diffraction effect of the crystal superlattice structure is similar to the x-ray diffraction phenomenon of low-temperature crystals, and it exists in the crystal in a three-dimensional structure.

Preparation of potassium tantalum niobate–barium titanate (KTN-BT) solid solution system ceramics and their piezoelectric properties

Potassium tantalum niobate (KTa1-yNbyO3, KTN)-barium titanate (BaTiO3, BT) solid solution system 0.02[KTN]-0.98[BT] ceramics with various microstructures were prepared by modified two-step sintering method, and their dielectric and piezoelectric properties were observed. For 0.02K(Ta0.5Nb0.5)O3-0.98BaTiO3 ceramics ferroelectric tetragonal crystalline structure was found for sintering temperature1230, 1240, 1250, 1260, and 1270 °C. A large grain growth was observed for the BT grains of the samples. By observing the strain vs. electric field curves slope apparent piezoelectric constant d33* was investigated. The piezoelectricity d33 is found in proportional to escaping weight % of potassium at increasing sintering temperatures. Enhanced piezoelectric constant d33* of value 391 pm/V was found for sintering temperature 1240 °C.

Design of the Photonic Crystal Slot Fractal Array Ultra Wideband Antenna

According to the performance requirements of the multi band compatible antennas for the mobile communication system, the radio frequency identification system, the ultra wideband system and the mobile digital TV system, the present paper originally combined photonic crystal structure, embedded slot fractal, rectangular array antenna, relative dielectric constant gradual thin film, potassium tantalum niobate thin film, Fe-based nanocrystalline alloy coating and graphene conductive ink, and designed a photonic crystal slot fractal array ultra wideband antenna. The result of test indicates that this antenna has strong anti-EMI capability, large performance redundancy and ultra wideband operation capability. This antenna completely covered all working frequency bands of the second generation to the fifth generation mobile communication, the frequency bands of the radio frequency identification system, the frequency band of the ultra wideband system, and the frequency band of the mobile digital TV system. This antenna has small size, high radiation intensity, stable and reliable operation performance; it is a microwave band multi network integration antenna with excellent performance.

Defect dipole evolution and its impact on the ferroelectric properties of Fe‐doped KTN single crystals

AbstractThe ferroelectric and piezoelectric properties of doped potassium tantalum niobate crystals with different Fe doping amounts and the adjustability of the properties are investigated. The hysteresis loops and current density curves show that the defect dipoles have an obvious effect on domain reorientation, and the effect decreases with increasing doping amount. The ferroelectric and piezoelectric properties can be adjusted via the defect dipoles, and the adjustability is reduced with increasing doping amount. A change of the doping amount leads to defect dipole structure evolution in the crystals, in which the defect dipoles transform from a polar structure to a nonpolar structure, which is the reason for the transition of the domain reorientation determined by the defect dipoles. This result has proved that introducing defects is an effective way to improve and regulate perovskite properties, and the doping amount is one of the important factors controlling the defect dipoles.

Nanorods of Potassium Tantalum Niobate Tetragonal Tungsten Bronze Phase Grown by Pulsed Laser Deposition

K–Ta–Nb–O tetragonal tungsten bronze phase was grown on (1102) Al2O3 (R-plane sapphire) by pulsed laser deposition. The microstructure, structure, and chemical composition of the deposit were studied by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectrometry, and transmission electron microscopy. The crystal structure was solved by precession electron diffraction as being tetragonal tungsten bronze-type structure with space group P4/mbm, refined cell parameters a = 12.537 ± 0.003 A, c = 3.975 ± 0.001 A, and composition K5.06(Ta0.57Nb0.43)10.99O30. The tetragonal potassium tantalum niobate growth follows two modes with respect to the substrate surface: (i) as single vertical right parallelepiped-shaped nanorods (50 to 100 nm wide and up to 1 μm in length) along the [001] direction and (ii) as in-plane attached crystals along the ⟨310⟩ direction. These two growth modes are understood as being governed by the plane termination of the substrate. This new phase is of potential in...

Terahertz-induced Kerr-effect in Relaxor Ferroelectrics

AbstractWe demonstrate the Kerr-effect induced by the electric field of single-cycle THz pulses in the relaxor ferroelectrics potassium-tantalum niobate KTa1-xNbxO3 (KTN) and K1-yLiyTa1-xNbxO3 (KLTN). We find a slow orientational relaxation with a time constant of 6 ps in KTN with x=1.8% at room temperature, that decreases upon approaching the transition temperature.

Chemical Solution Deposition and Infrared Study of K(Ta,Nb)O3 Thin Films

Potassium tantalum niobate (KTa x Nb 1− x O 3 , (KTN), where x = 0, 0.21, 0.36, 0.53, 0.74, 0.82, 0.86, and 1) thin films were prepared by chemical solution deposition (CSD) on Si substrates. A homogeneous and stable sol was obtained by dissolving potassium, niobium and tantalum isobutoxides in absolute isobutanol, refluxing for 30 min and adding diethanolamine as a modifier. The sol was deposited by spin coating. KTN perovskite films were successfully prepared only on substrates covered with Al 2 O 3 “chemical” and KNbO 3 seeding buffer layers, otherwise a pyrochlore structure was preferred. Annealing temperature and heating regime were also important factors for film quality. The powder X-ray diffraction confirmed that the prepared films had pseudocubic perovskite structure. The infrared transmittance spectrum of the films for high concentration of Ta shows three minima corresponding to optical active phonons in the perovskite crystal structure. Their positions are in agreement with those for the bulk material, except for the 14 cm−1 shift of the lowest phonon, which has been also observed in other perovskite materials. The temperature dependence of the phonon parameters has also been studied, too.

Ferroelectric thin films with polarization gradients normal to the growth surface

Thin film ferroelectrics with polarization gradients normal to the growth surface readily form when gradients in temperature, strain, or composition are coupled to the polarization vector in ferroelectric materials. This letter describes the formation of thin films of potassium tantalum niobate with graded polarizations obtained by grading the tantalum to niobium ratio of the ferroelectric phase. Unlike a simple structure consisting of laminated layers of ferroelectric material, the polarization gradient which forms breaks the natural symmetry of the ferroelectric material at any given plane, resulting in a self-poling of the structure subsequent to excitation by an oscillatory electric field. Once poled, the devices reveal a measurable potential across the structure which varies with temperature.

Infrared imaging using uncooled focal plane arrays of unreticulated 10- mu m potassium tantalum niobate films

Potassium tantalum niobate (KTN) films, 10- mu m thick, with a nominal Curie temperature of -20 degrees C were formed on polished platinum-coated sacrificial yttria substrates by metalorganic deposition (MOD). These KTN films were used to fabricate focal plane arrays consisting of 128*128 pixels with each pixel on 50- mu m centers and 50- mu m/sup 2/. Using f/1 optics and a 2.5-V/ mu m/sup 2/ detector bias, a noise equivalent temperature (NE Delta T) of 0.65 degrees C was obtained for the best 1% of the pixels when the detector and blackbody source operated at 25 degrees C. >

Effects of Sintering Temperature and Time on Grain Size and Dielectric Constant of Potassium Tantalum Niobate Films

Thin films of potassium tantalum niobate (KTN) formed by metalorganic deposition were subjected to one‐ and two‐step sinterings in air and potassium atmosphere. These polycrystalline films were found to be mechanically robust and display electrical properties similar to single‐crystal KTN. This report shows that film grain size increased with sintering temperature and time. Scanning electron micrographs revealed grain sizes ranging from submicrometer to 5 μm in diameter. The maximum relative permittivity, its corresponding rate of change with temperature, and film grain size were measured as a function of sintering temperature and time.

Characterization of potassium tantalum niobate films formed by metalorganic deposition

Thin films of potassium tantalum niobate, KTa0.6Nb0.4O3, with a Curie temperature of 20 °C were deposited on a variety of substrates by metalorganic deposition. These films had peak relative permittivities of 16 000 at 20 °C. Hysteresis plots of electric displacement as a function of electric field, taken at 0 °C, revealed a coercive field of 800 V/cm, a spontaneous polarization of 3.9 μC/cm2, and a remnant polarization of 0.5 μC/cm2. The hysteresis loops did not change significantly as the temperature was varied down to −100 °C.

Charge pumping and pseudopyroelectric effect in active ferroelectric relaxor-type films.

Unidirectional charge flow was observed in potassium tantalum niobate, ${\mathrm{KTa}}_{0.6}$${\mathrm{Nb}}_{0.4}$${\mathrm{O}}_{3}$, films. These films of relaxor-type diffuse phase transition material were formed by metalorganic deposition and had a polarization gradient normal to the surface of the films. Novel charge pumping was observed in the active operation of simple two-terminal structures by excitation with periodic, strong electric fields. Such operation also showed a large pseudopyroelectric response. Effective pyroelectric coefficients as large as 2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$ C/${\mathrm{cm}}^{2}$ \ifmmode^\circ\else\textdegree\fi{}C have been obtained.

Physical characterization of electronic materials devices and thin films (1.12.69–1.12.70) : S. A. Kulin and K. Kreder. Manlabs. Inc., Cambridge Mass, U.S.A. P-177101. AFCRL-71-0204. F-19628-70-C-0140 SC-R-1. January (1971), 46 pp

Abstract : In support of research being conducted by the Properties and Phenomena Branch, Solid State Science Laboratory, Air Force Cambridge Research Laboratory, ManLabs, Inc. is conducting a service effort that is directed toward the characterization of specified physical, chemical and structural properties of various materials. Experimental methods include chemical analysis, reflection electron microscopy and diffraction, X-ray diffraction and fluorescence analysis, light microscopy and electron microprobe analysis, in addition to the determination of specific properties, such as density, hardness and thermal conductivity. Special services, such as crystal orientation, cutting, grinding and polishing are also being performed. Specific materials submitted for characterization include spinel, lithium germanate, silicon, silicon carbide, quartz, ruby, magnesium oxide, copper chloride, gallium arsenide, boron, potassium tantalum niobate, yttrium-iron garnet, yttrium-aluminum garnet and lithium niobate. In addition, a variety of specimens have been submitted for specific studies such as phase identification, crystallinity and chemical analysis. (Author)

Growth of KTaO3-KNbO3 Mixed Crystals

Crystals of potassium tantalum niobate (KTN) were grown by two techniques: (1) pulling in the 〈100〉 direction with a continuously increasing crystal diameter, and (2) growing {100} platelets while floating on the surface of the melt. The amount of tantalum in the crystals increased rapidly with increasing potassium in the melt. The rate of potassium oxide evaporation from the melt was significant.