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Phase transitions in Rochelle salt [sodium potassium l(+)‐tartrate tetrahydrate] are revisited in a single‐crystal X‐ray diffraction multi‐temperature study on cooling from 308 to 100 K across the high‐temperature paraelectric (PE) ↔ ferroelectric ↔ low‐temperature PE phase transition points. The results of structure refinement using three different models (a harmonic with and without disorder, and an anharmonic) were compared. The temperature dependencies of anisotropic displacement parameters (ADPs) and Ueq, which can be calculated directly from ADPs, for the low‐temperature PE phase indicate clearly the dynamic nature of disorder of the K1 atoms. The structures of the low‐temperature and the high‐temperature PE phases are compared for the first time at multiple temperatures for each phase based on diffraction data collected from the same single crystal. The data indicate that the high‐temperature and the low‐temperature paraelectric phases are probably not two different phases, as was assumed in earlier works, but are structurally the same phase at different temperatures. [ABSTRACT FROM AUTHOR]

The current work investigates the structural, optical, electrical, and mechanical properties of Rochelle salt (RS)-doped polyvinyl alcohol (PVA) composite. The RS with concentrations (0 to 50 wt%)-filled PVA were prepared via the casting method. X-ray diffraction (XRD) of PVA and RS indicates the semi-crystalline nature of PVA and the crystal nano-size of RS. Moreover, the XRD of RS-doped PVA composites confirms the interaction and miscibility between PVA and RS. The changes in molecular structure were investigated by using attenuated total reflection—Fourier transform infrared spectroscopy (ATR-FTIR) and confirmed the interaction and structure change in PVA by doping RS. The optical properties of the RS-doped PVA composites are greatly dependent on the RS concentrations. The absorption edge, direct, and indirect band gap increase with doping RS compering with pure PVA. The dielectric constant, loss, real and imaginary parts of dielectric modulus, and alternating current (AC) conductivity were investigated. Decrease in dielectric constant and loss followed by constant values with frequency increase due to the interfacial polarization. Also, increased AC conductivity and dielectric moduli with frequency increase and only a single relaxation peak were found and shifted to lower frequencies by increasing RS concentrations. Moreover, mechanical measurements reveal a significant improvement in the flexibility of RS-doped-PVA composites. The modulus of elasticity decreased by 72% compared with pure PVA. Dynamic mechanical analysis also reveals a decrease in storage modulus by 76% compared with pure PVA. Also, the RS concentrations greatly affect peak height, width, and position of loss factor. [ABSTRACT FROM AUTHOR]

A straightforward and inexpensive electrophoretic method for obtaining environment-friendly nanocrystalline piezo layers from Rochelle salt (RS) is presented here. The electrophoretic deposition process includes the formation of nanocrystals by precipitation of Rochelle salt/water solutions in ethanol (anti-solvent method) under the influence of a high electric field. A nanoporous anodic aluminum oxide membrane is used to separate the electrochemical cell into two chambers. The composition of the RS:H2O:EtOH mixture and the spatial separation of the process of precipitation from electrophoretic deposition allow control of the nanocrystal size and the uniformity of the layer. The reaction kinetics, the morphology, and the piezo response to the resulting layers are all investigated. The best samples were obtained at RS:H2O:EtOH ratio 1:22.5:37.5. Under these conditions, the nanocrystals are preferentially oriented on the aluminum substrate and form a dense and homogeneous layer. Although the obtained structure is polycrystalline, the resulting piezo effect is 1120 pC/N, which is comparable to inorganic monocrystals and piezoceramics. This allows the use of electrophoretically deposited polycrystalline piezo layers in applications such as energy harvesting. [ABSTRACT FROM AUTHOR]

Atom Transfer Radical Polymerization (ATRP) is an effective catalytic process leading to well-defined polymers with desired properties. This process based on reversible deactivation of propagating chains has a lower rate in comparison with conventional radical polymerization, especially in the case of obtaining polymers with high molecular weights. Thus, the increase of the rate of this process with preserving control over molecular weight distribution is a challenging task. In this work, novel catalytic systems for Activators Generated by Electron Transfer (AGET) ATRP of acrylonitrile based on copper (II) bromide complexes were proposed. It was found that Rochelle salt (potassium sodium tartrate tetrahydrate) may be used as a reducing agent for regeneration of copper-based catalysts to increase the rate of the process. The provided UV-vis spectroscopy experiments have confirmed the reducing ability of tartaric anion. It was found that the use tandem catalytic system based on two copper complexes with different ligands also increases the polymerization rate. The performed experiments allowed us to develop a catalytic system for rapidly obtaining polyacrylonitrile polymers with desired molecular weights exceeding 100 kDa. [ABSTRACT FROM AUTHOR]

The study provides frequency spectra of several electrophysical parameters of dielectric permittivity, dielectric loss tangent, conductivity, electrical impedance and electric modulus to explore the frequency response at low and infralow frequencies (10−2–106 Hz) for the ferroelectric composite synthesized from cellulose nanoparticles and Rochelle salt. The experimental results confirmed the main contribution of conductivity into the frequency response with the presence of two relaxation processes. The first one was related to the intrinsic relaxation inside the composite while the second one was caused by the influence of electrode effects. Besides, the significant dispersion of dielectric permittivity obeying Maxwell-Wagner-Sillars mechanism has also been detected. [ABSTRACT FROM AUTHOR]

In general, everyone wants new technology to survive in this competitive world. In the segment of instrumentation, the transducer is one of the electrical devices well suited for domestic and small-scale industry applications. Uniqueof the new technologies in the transducers by means of piezoelectric transducer is widely used in the electrical and mechanical field applications. So in this review paper, various piezoelectric materials are discussed along with their physical properties and benefits. Current applications with piezoelectric transducers are deliberated and evaluated based on the physical properties of these piezoelectric materials. [ABSTRACT FROM AUTHOR]

The present study is devoted to clarifying effects of carbonization toward cellulose nanoparticles that are pre-carbonized at different temperatures of 240, 250, 340 and 400 °C on the phase transition and conductive properties of nanocomposites with Rochelle salt. Fourier-transform infrared spectroscopy (FTIR) technique was employed to investigate the changes in functional groups during carbonization process. The results indicated that the influence of carbonized cellulose component on properties of Rochelle salt volume part in the composite was negligible, but significant at the interfaces between Rochelle salt and surrounding cellulose. The elevated carbonization temperatures resulted in the reduction of phase transition temperatures and increase in conductivity. The weakness of Rochelle salt/cellulose interaction caused by carbonized cellulose and the formation of carbon clusters in the composite were considered as the main reasons for anomalous phase transition and high electrical conductivity, respectively. [ABSTRACT FROM AUTHOR]

This study presents experimental results of investigating dielectric properties of ferroelectric composite prepared from Rochelle salt and cellulose nanoparticles under a weak electric field of 1 V/cm from 5 to 55 °C. It was found that along with the upper phase transition coinciding with those for bulk Rochelle salt (24 °C) detected due to the presence of Rochelle salt volume part and clusters, the strong interaction at cellulose/Rochelle salt interfaces led to the appearance of an additional phase transition at higher temperature (47 °C). Correspondingly, two relaxation regions for Rochelle clusters and cellulose/Rochelle salt interfaces in the frequency range of 102–107 Hz were observed. [ABSTRACT FROM AUTHOR]

This present work is devoted to clarifying the influence of hydrogen bonds on dielectric relaxation properties of classical hydrogen-bonded ferroelectrics (triglycine sulfate, Rochelle salt) in the ferroelectric phase at low frequencies of 102–107 Hz under weak electric field (1 V/cm). For this purpose, two nanocomposites (silicon dioxide nanoparticles/triglycine sulfate and cellulose nanoparticles/Rochelle salt) have been synthesized. The results showed that under the influence of silicon dioxide and cellulose, the relaxation frequencies of triglycine sulfate and Rochelle salt were lower than those for its single crystals of ferroelectrics. Besides, the increase in dielectric inclusion content led to the shift of relaxation frequencies toward lower frequencies. The strong interaction between dielectric and ferroelectric components through hydrogen bonds was supposed to be the reason for the obtained anomalies. [ABSTRACT FROM AUTHOR]

The short-circuit current flow in crystals with the low-temperature phase transitions including Rochelle salt NaKC4H4O6 · 4H2O and triglycine sulfate (CH2 · NH2 · COOH)3 · H2SO4 is investigated. The experiments are conducted on polar cut samples without preliminary polarization with the symmetric indium conducting coatings. The short-circuit currents remaining for a fairly a long time and the current decay with time are observed at room temperature on all the samples. The temperature dependences of the short-circuit currents in the temperature ranges of 16 to 45°С for Rochelle salt and 16–110°С for triglycine sulfate are obtained. The short-circuit currents are observed in these crystals both in the ferroelectric and paraphase. It is shown that, upon heating in the ferroelectric phase, the total short-circuit current is determined by competing processes: the pyroelectric currents and electrochemical decomposition currents. In the paraphase, the short-circuit currents are the electrochemical self-decomposition currents. Based on the experimental results obtained, it is demonstrated that the short-circuit current flow through the polar cut samples of Rochelle salt and triglycine sulfate crystals is induced by the intrinsic emf caused by the electrochemical self-decomposition of the opposite surfaces of the sample polar cuts when in contact with the conducting coatings due to the anisotropy of these surfaces. A model of the electrochemical self-decomposition in such crystals is proposed. [ABSTRACT FROM AUTHOR]

This paper reports the successful extension of the basis of the X‐ray multiple diffraction phenomenon in the assessment of structural phase transitions and the determination of thermal expansion coefficients along three crystallographic directions, using synchrotron radiation Renninger scans. Suitable simultaneous four‐beam cases have accurately resolved the lattice‐parameter variation in a nearly perfect single‐crystal Rochelle salt using a high‐stability temperature apparatus. Secondary reflections observed in the Renninger patterns, chosen by their sensitivity to the shifts in angular position as a function of temperature, have allowed the detection of a monoclinic to orthorhombic phase transition, as well as subtle expansions of all the basic lattice parameters, i.e. without having to carry out measurements on each crystal axis. The thermal expansion coefficients have been estimated from the linear fit of the temperature dependence of the lattice parameters, and are in agreement with those reported in the literature. [ABSTRACT FROM AUTHOR]

The NMR spectra and the spin-lattice relaxation times, T1, of Rochelle salt crystals were studied as functions of temperature. Two groups of resonance lines were found in the 23Na and 39K NMR spectra of the paraelectric phases below TC1 and above TC2, whereas four groups of resonance lines were obtained in the 23Na and 39K NMR spectra of the ferroelectric phase between TC1 and TC2. To investigate the extra two groups of resonance lines in the ferroelectric phase, the stress-strain hysteresis loop of the Rochelle salt crystal was obtained, and the ferroelastic character of the Rochelle salt crystals suggested by Sapriel's theory was established by the relationship between the 23Na and 39K NMR spectra and the stress-strain hysteresis loop results. Therefore, ferroelastic and ferroelectric properties coexist in the phase between TC1 and TC2. [ABSTRACT FROM AUTHOR]

The dielectric properties of the crystals of nominally pure triglycine sulphate (TGS), deuterated TGS, TGS doped with L,α – alanine, TGS with impurity of phosphorus P5+ ions, TGS subjected to X-ray radiation as well as of Rochelle salt crystal were investigated. Temperature dependences of domain components of the real and imaginary parts of the dielectric permittivity measured in a weak ac electric fi eld were obtained. The existence of a moveable domain structure in defect-free TGS crystals does not lead to a deviation from the thermodynamic Curie – Weiss law in the ferroelectric phase, but causes a violation of the “law of two”. In TGS crystals with impurity or radiation defects, pinning the domain structure, the both laws work well. For the studied crystals of the TGS group near the phase transition, there is no quantitative correlation between temperature behavior of static geometric parameters of the domain structure (density N and total length L of the domain boundaries), and the measured dielectric characteristics. The number of thermal cycles of heating and cooling with a transition through the Curie point practically does not affect the value of the domain component of the dielectric constant in TGS crystals, while an increase of the rate of passage of the phase transition leads to its signifi cant decrease. In Rochelle salt crystals the domain part of the dielectric permittivity near the lower phase transition is considerably less than near the upper one, but it occupies a wider temperature range.

An eco-friendly ferroelectric nanocomposite from cellulose nanoparticles (CNP) and Rochelle salt (RS) at different composition mass ratios was synthesized for clarifying phase transition anomalies after carefully characterizing by scanning electron microscope (SEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) techniques. The dielectric experiments were conducted in a temperature range from 5°C to 60°C under a weak electric field (2 V/cm) at 1 kHz. The obtained results indicated the presence of the upper Curie point characteristic for volume part of RS in the composite and an additional higher-temperature phase transition which was shifted toward higher temperature with increasing CNP content. Besides, at relatively high CNP content, the ferroelectric phase of RS maintained up to its decomposition temperature. The intermolecular hydrogen bonds formed between cellulose and Rochelle salt is assumed to be responsible for the obtained anomalies. [ABSTRACT FROM AUTHOR]

Shows that in strongly piezoelectric solids such as Rochelle salt and Ba[sub2]NaNb[sub5]O[sub15] the longitudinal sheet of the acoustic slowness surface may possess regions where one or both of the principal curvatures is negative. Discussion on coupled electric acoustic waves; Calculation of the centered section of the slowness surface of Rochelle salt.

Presents a study which examined the domain switching of ferroelectric triglycine sulfuric acid and Rochelle salt by observing optical gyration along the ferroelectric axes and measuring rotation of the indicatrices around the same axes. Method for distinguishing the twinning mechanism of the ferroelectric domains; Change of gyration and orientation of indicatrix; Observations of the optical phenomena.

Rochelle Salt is used as an efficient catalyst for the synthesis of 2,4,5-triaryl-1H-imidazoles via condensation of benzil, ammonium acetate, and aromatic aldehydes. The key advantages of this process are the usage of an inexpensive and readily available catalyst, simple procedure, shorter reaction time, and high yield of products. DOI: http://dx.doi.org/10.17807/orbital.v7i3.720

Inorganic perovskite ferroelectrics are widely used in nonvolatile memory elements, capacitors, and sensors because of their excellent ferroelectric and other properties. Organic ferroelectrics are desirable for their mechanical flexibility, low weight, environmentally friendly processing, and low processing temperatures. Although almost a century has passed since the first ferroelectric, Rochelle salt, was discovered, examples of highly desirable organic perovskite ferroelectrics are lacking. We found a family of metal-free organic perovskite ferroelectrics with the characteristic three-dimensional structure, among which MDABCO (N-methyl-N’-diazabicyclo[2.2.2]octonium)Ðammonium triiodide has a spontaneous polarization of 22 microcoulombs per square centimeter [close to that of barium titanate (BTO)], a high phase transition temperature of 448 kelvins (above that of BTO), and eight possible polarization directions. These attributes make it attractive for use in flexible devices, soft robotics, biomedical devices, and other applications. [ABSTRACT FROM AUTHOR]

In this work we demonstrate the role of a ligand in formation of the conductive and electrocatalytically active copper microstructures produced using the in situ laser-induced metal deposition technique. For this purpose, the alkaline solutions of different concentrations containing copper(II) chloride and Rochelle salt, which is used as the ligand and exhibits both coordination and reduction properties, were studied by ATR-FTIR, UV–Vis, and Raman spectroscopy. According to spectroscopic studies and theoretical considerations, it was observed that at certain concentrations and proportion of copper(II) chloride and sodium potassium tartrate, and also within pH range between 7 and 13 the components of the plating copper solution form the tartrate copper complex, in which copper ion is coordinated by four hydroxyl groups of the ligand and two hydroxyl groups of the environment. As a result, the laser-induced deposition from solutions, where copper coordination occurs via hydroxyls rather than through other functional groups (e.g. carboxylate), results in the synthesis of the sensory active materials. Furthermore, we figured out that the presence of the reducing agents such as polyols in the plating copper solution also enhances the electrical conductivity and electrochemical characteristics of the resulting copper microdeposits, among which sorbitol displays the most attractive results. Thus, it was shown that the regime of copper coordination in an organic ligand and number of hydroxyl groups in a ligand and a reducing agent directly affect the properties of the synthesized copper microstructures. In addition, the overall results obtained in this study are quite useful for better understanding the mechanisms of the laser-induced metal deposition process, and very perspective for development and design of new non-enzymatic electrochemical sensors and biosensors. [ABSTRACT FROM AUTHOR]

Sodium potassium tartrate tetrahydrate-NaKC 4 H 4 O 6 ·4H 2 O known as Rochelle salt is a well-known ferroelectric. This paper deals with the following topics: (i) the Sankaranarayanan-Ramasamy method of growth of a parallelepiped-shaped single crystal of Rochelle salt having the (1 0 0), (0 1 0) and (0 0 1) planes mutually perpendicular to each other, (ii) evaluation of the second-order elastic stiffness constants C 11 , C 22 , C 33 , C 44 , C 55 and C 66 using the parallelepiped-shaped single-crystal sample of Rochelle salt , (iii) growth of large [0 1 1]-, [1 0 1]- and [1 1 0]-oriented cylindrical-shaped single crystals of Rochelle salt from appropriately prepared seeds using the same method, (iv) determination of elastic constants C 23 , C 13 and C 12 using the [0 1 1]-, [1 0 1]- and [1 1 0]-oriented single-crystal samples of Rochelle salt, respectively, and (v) calculations of elastic compliance constants S 11 , S 22 , S 33 , S 44 , S 55 , S 66 , S 12 , S 23 and S 13 , Young’s modulus E , bulk modulus K , Poisson’s ratio υ , linear compressibility β 1 , β 2 and β 3 along the three principal directions and volume compressibility β of the crystal. [ABSTRACT FROM AUTHOR]

Triglycine sulphate (TGS) is well-known ferroelectric crystal, finding many applications in IR detectors and laser devices. Triglycine sulphate crystal was grown by conventional method using water as a solvent. The 1 mol% of semiorganic piezoelectric material Rochelle salt (RS) is added into the pure TGS to enhance its optical, photoluminescence and piezoelectric properties. The crystallinity of the grown crystals was examined by powder X-ray diffraction analysis. Optical transmittance shows that the RS doped TGS possesses higher transparency compared to pure TGS. High intense luminescence at 442 nm for the RS doped TGS single crystal is observed from the photoluminescence study. The negative photoconductivity nature is observed for both pure and RS doped TGS and it was studied under different conditions such as dark, light and also under different temperatures such as at Curie temperature, above and below Curie temperature. Low dislocation density for RS doped TGS crystal is observed from chemical etching analysis. The piezoelectric d 33 co-efficient is also increased as a result of RS doping in TGS. [ABSTRACT FROM AUTHOR]