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To determine the formation possibility of 2,6‐diamino‐3,5‐dinitropyrazine‐1‐oxide (LLM-105) /ammonium perchlorate (AP) mixed crystal, the dimer configuration of LLM-105/AP was screened. Three possible configurations (LLM-105/AP1, LLM-105/AP2, and LLM-105/AP3) were obtained, and the mixed crystal of LLM-105/AP and AP'/AP crystal were examined. The binding energy (Ebind), electrostatic potential (ESP), and electronic density topology (AIM) of the dimers of LLM-105/AP were evaluated. Then the radial distribution function (RDF) between nitrogen atoms and oxygen atoms specified in LLM-105/AP and the length distribution of trigger bonds was calculated. The results revealed the hydrogen bonds in those configurations of LLM-105/AP. The binding energy of the three configurations corresponded to 29.7363, 20.8283, and 19.2166 kcal·mol−1. The sequence of the electron density ρ(r) at the bond critical point (BCP) was LLM-105/AP1 > LLM-105/AP2 > LLM-105/AP3. The noticeable peaks were observed in LLM-105/AP and AP'/AP at 0.11–0.31 nm. The Lmax values in LLM-105/AP and AP'/AP were 0.1080 nm and 0.1086 nm, respectively. Therefore, it is possible for LLM-105 and AP to form a mixed crystal. The sensitivity of AP decreased with the addition of LLM-105. The zero oxygen balance could be reached at LLM-105: AP mass ratios between 50:50 and 40:60. [ABSTRACT FROM AUTHOR]

TiO2 gel was synthesized by the sol–gel method, and TiO2 photodegradation material (TiO2-PDM) was obtained after drying, grinding, and heat treatment, which was used for photodegradation of Congo Red wastewater. The Rietveld refinement method confirmed that the TiO2 material was anatase crystal when the calcination temperature was lower than 600°C. When the calcination temperature was between 600 and 750°C, the TiO2 material was anatase-rutile mixed crystal, and the proportion of rutile increased gradually. The content of the rutile crystal reached 98.3% at 800°C. Compared with TiO2-PDM at 800°C, TiO2-PDM at 500°C has a smaller crystal size and better dispersibility. The best photodegradation performance was identified as the 77.1% when the drying temperature was 80°C, the calcination temperature was 500°C, and the calcination time was 1.5 h. [ABSTRACT FROM AUTHOR]

Nine new C3-symmetric 2,7,12-tris(decanoxy)-3,8,13-tris(alkoxy)truxene discogens were synthesized, and all exhibited only one three-dimensionally ordered hexagonal columnar mesophase with a wide mesogenic temperature range, as characterized by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffractometry. Crucially, as the length of the alkoxy chain increased, the melting points first increased and then decreased, and, at the same time, the temperatures of the clearing point decreased gradually. In addition, these compounds were found to be highly thermally stable, having decomposition temperatures occurring well above 350°C, as determined by thermogravimetric analysis. The self-assembly behaviors in solution were studied using variable-concentration 1H-NMR, revealing that the truxenes self-aggregated in solution via the π–π facial interactions of the polycyclic aromatic units, and scanning tunneling microscopy results revealed that one of the discotic liquid crystal compounds periodically assembled in a hexagonal geometry at the liquid–solid interface of highly oriented pyrolytic graphite. [ABSTRACT FROM AUTHOR]

New four-ring ester/azomethine/ester liquid crystal series, 4-alkoxybenzoyloxy 4'-phenylazomethine phenyloxy 4"-alkoxybenzoate In, were prepared, and their thermal stability and mesomorphic activity were investigated. The two wing carboxylic units were used aiming to achieve new mesomorphic properties for the prepared materials. The two ester linkages and the two terminal alkoxy chains were incorporated to modify the molecular structure. The chemical structures of the synthesised compounds were confirmed via FT-IR, NMR and elemental analysis. Differential scanning calorimetry (DSC) and polarising optical microscopy were applied to determine the mesomorphic features of the designed homologues. All of the studied homologous were shown to exhibit superior thermal stability and enormous mesomorphic temperature ranges. Moreover, enantiotropic smectic A and nematic phases were shown to cover all of the homologues. The influence of inclusion the di-ester moieties on the mesophase behaviour was investigated through a comparison with the previously investigated three-ring series bearing only one ester linkage. Two binary phase diagrams were constructed and addressed in terms of the smectic and nematic temperature ranges. [ABSTRACT FROM AUTHOR]

Rotational viscosity coefficient is an important material parameter affecting the dynamic response of liquid crystals. We evaluated the dynamic response of two series of mixed liquid crystals SCL17V33L00 and SCL17V28L00 with negative dielectric anisotropy on the basis of the accurate measurement of rotational viscosity. At the temperature of 25°C, 30°C and 35°C, the parallel and vertical dielectric constants of them were calculated from the dual-cell capacitance model and liquid crystal cell capacitance model. Then, the bend and splay elastic constants of them were determined by analysing the Fréedericksz transition threshold voltage in the vertically aligned nematic cell and comparing the liquid crystal layer capacitance–voltage curve through the finite-differential iteration method with experimental curve. At last, the rotational viscosity coefficients γ1 of them were obtained by performing dynamic response simulation using Visual Fortran software. As the temperature increases, the rotational viscosity coefficient of them decreases. Although the rotational viscosity coefficient of the second mixed liquid crystal was relatively large under the same temperature, the viscoelastic ratio coefficient was small, and the figure-of-merit was large, thereby resulting in a relatively fast dynamic response. [ABSTRACT FROM AUTHOR]

The adamite-olivenite solid-solution series includes three mineral species (adamite, zincolivenite, and olivenite) defined by the proportions of copper and zinc in each of two ordered cation sites in the crystal structure. Adamite and zincolivenite are both orthorhombic, and olivenite is monoclinic; however, the symmetry change occurs at about 80 mole percent copper, so that the speciation for compositions between 75 and 80 mole percent copper is poorly defined. Once copper becomes the dominant cation (i.e., greater than 50 mole percent) in that site, the overall copper ratio (including both cation sites) exceeds 25 mole percent, and the mineral moves into the compositional range of zincolivenite. Once copper exceeds 50 mole percent in the second site (i.e., greater than 75 mole percent overall), however, the upper limit of copper content by which zincolivenite is defined is exceeded. Potentially, this introduces a further problem of nomenclature (although not an issue in the context of the current article); zincolivenite is defined as containing between 25 and 75 mole percent copper, but in synthetic members of the series the symmetry change from orthorhombic to monoclinic occurs at around 80 mole percent copper (Toman [27], [28]; see fig. 7). [Extracted from the article]

Herein, in order to determine the formation feasibility of 1,1-diamino-2,2-dinitroethylene (FOX-7)/ ammonium perchlorate (AP) mixed crystals, three configurations of FOX-7/AP composites (FOX-7/AP1, FOX-7/AP2, FOX-7/AP3) were optimised, and the structures of FOX-7/AP mixed crystals were constructed. Then the electrostatic potential, binding energy and electronic density topology of FOX-7/AP composites were calculated by using the density functional theory. Finally, the radial distribution function between H atoms and O atoms of FOX-7/AP mixtures was calculated through molecular dynamics. As demonstrated by the results, there are hydrogen bond interactions in three configurations of FOX-7/AP composites. The interaction energies of FOX-7/AP1, FOX-7/AP2 and FOX-7/AP3 are 8.396, 20.537 and 38.189 kJ▪mol−1, respectively. The order of the electron density ρ(r) at the bond critical point (BCP) of three FOX-7/AP composites is FOX7-AP3 > FOX7-AP2 > FOX7-AP1. There are apparent peaks at the range of 0.11–0.31 nm and 0.31–0.5 nm for FOX-7(10-1)/AP, FOX-7(011)/AP, FOX-7(101)/AP mixed crystals. The interaction strength of the hydrogen bond is greater than that of strong van der Waals force. Therefore, it is feasible to combine FOX-7 with AP to form mixed crystals. As the content of AP in the mixed crystal is on the rise, the oxygen balance of the system shows a gradually increasing trend. [ABSTRACT FROM AUTHOR]

TiO2 has been widely accepted in various photocatalysts due to its low cost, high stability, structural robustness and non-toxicity. Hydrothermal method was used to prepare TiO2 photocatalysts with different morphology, structure and crystal morphology, including three-dimensional TiO2 spheres, shuttle-shaped TiO2, one-dimensional nanorod TiO2 and nanotube TiO2 films. The photocatalytic degradation of methylene blue by titanium dioxide with five different morphologies under white light was characterized by scanning electron microscope, X-ray diffraction, fourier transform infrared spectroscopy and ultraviolet visible light absorption spectroscopy, and the effects of morphology, structure and crystal type on TiO2 performance were analyzed. The preparation methods of titanium dioxide photocatalyst with good properties were compared. It is proven that higher crystallinity, small particle size, larger specific surface area, higher absorbance and a certain proportion of mixed crystal phase are beneficial to obtain better photocatalytic performance. [ABSTRACT FROM AUTHOR]

The impact of formulation variables on the optimization of pilot scale clobetasol 17-propionate (CP) cream formulations was investigated using a Central Composite Design of Experiments. Thirty batches of cream were manufactured and the formulation variables assessed were % v/v propylene glycol, % w/w Gelot® 64, cetostearyl alcohol and glyceryl monostearate content. The responses monitored included viscosity, spreadability, pH, CP content, extrudability, electrical conductivity, and % CP released at 72 hours. The responses were compared to those of a reference product, Dermovate® cream. ANOVA analysis revealed that viscosity, spreadability, and % CP released at 72 hours were significant formulation responses (p < 0.05). Cetostearyl alcohol had the greatest impact on quality of pilot scale products. An increase in cetostearyl alcohol resulted in an increase in viscosity, a decrease in spreadability, and a decrease in % CP released at 72 hours. The optimized pilot scale CP formulation contained 46% v/v propylene glycol, 8.6% w/w cetostearyl alcohol, 10.5% w/w glyceryl monostearate, and 3.8% w/w Gelot® 64. The resultant viscosity, spreadability, pH, CP content, extrudability, electrical conductivity, and % CP released were 44633cP, 24.91cm2, 101.23 %, 76.98 g/cm2, 198.23 µS/cm, and 50.23%. The addition of cetostearyl alcohol and Gelot® 64 is critical for establishing a soft formulation that leads to the formation of a mixed crystal bilayer network of high viscosity. The formation of a separate crystalline lipophilic network usually occurs in semi-solid formulations that contain high concentrations of emulsifier, leading to an increase in shear stress and greater physicochemical stability of the formulation. The use of experimental design approaches to formulation development activities, permit evaluation of multiple factors simultaneously, reducing the time and costs asscoiated with product development activities, whilst identifying a composition design space and ensuring stable and effective dosage forms are produced. [ABSTRACT FROM AUTHOR]

ADP:KDP (85:15) mixed crystal was grown using slow cooling technique. The crystalline perfection of the grown crystal was studied using HRXRD curve. The homogeneity of KDP along the length of mixed crystal was analysed. Low Urbach energy value of the grown crystal indicates good crystallinity of the mixed crystals. Etch pit density was found using chemical etching studies. Vickers hardness studies indicate that the quality of the mixed crystal is more stable compared to ADP. The photoconductive nature and piezoelectric coefficient of the crystal were found. The laser stability of the crystal was observed at 532 nm using Nd:YAG laser. Mixed crystal of AKDP in the ratio of 85:15 was successfully grown using slow cooling technique with a size of 45 × 10 × 10 mm3 Homogeneity of mixed crystal along the entire length of crystal was analysed The band tail energy (Urbach Energy EU) of the grown crystal was EU = 0.91eV. The calculated etch-pit density for the mixed crystal was 3.6 × 103/cm2 The piezoelectric charge d33 value obtained for the mixed crystal was 6 pC/N. [ABSTRACT FROM AUTHOR]

Cu6PS5Br1-xClx mixed crystals were grown by chemical vapour transport. Optical absorption edge and optical polarization measurements were performed in the temperature range 77–320 K. The influence of anionic Br→Cl substitution on the phase transitions in Cu6PS5Br1-xClx mixed crystals is studied. Compositional dependence of the ferroelastic phase transition temperature for Cu6PS5Br1-xClx mixed crystals is obtained. The variation of optical parameters at ferroelastic phase transition is analyzed. [ABSTRACT FROM AUTHOR]

The Winsor & NewtonTM(W&N) nineteenth century archive database includes digitised images of hand-written instructions and workshop notes for the manufacture of their artists’ materials. For the first time, all 183 production records for yellow lead chromate pigments were studied and evaluated. They revealed that W&N produced essentially three pigment types:lemon/palebased on mixed crystals of lead chromate and lead sulphate [Pb(Cr,S)O4];middleon pure monoclinic lead chromate [PbCrO4]; anddeepthat contains the latter admixed with basic lead chromate [Pb2CrO5]; accounting for 53, 22, and 21% of the production, respectively. Production records for primrose (4%) were also included since the formulation results in mixed crystals with a high percentage of lead sulphate, which, according to the literature, leaves it more prone to degradation. Each pigment type is characterised by only one or two main synthetic pathways; process variations reveal a systematic and thorough search for a high-quality durable product. A comparison of the chemical composition of pigment reconstructions with early W&N oil paint tubes showed that their records entitled ‘pale’ and ‘lemon’ correlated with the pigment in their tube labelledchrome yellowand, ‘middle’ and ‘deep’ with the labelchrome deep. Lemon and middle pigment formulations were made into oil paints to assess their relative photo-stability. The degradation process was followed by colorimetry and was studied by synchrotron radiation-based techniques. Based on the X-ray absorption spectroscopy data, the possibility for creating a stability index for chrome yellows is discussed. [ABSTRACT FROM PUBLISHER]

Mixed crystals Rb3(HSO4)2.5(H2AsO4)0.5have been prepared by slow evaporation from aqueous solution at room temperature. The crystals were characterized by X-ray single analysis, which revealed that Rb3(HSO4)2.5(H2AsO4)0.5crystallizes in the space group P with lattice parameters:a= 7.471(3) Å;b= 7.636(1) Å;c= 12.193(2) Å; α = 71.91(1)°; β = 73.04(6)° and γ = 88.77(2)°. In this structure, the ordered S(1)O4and the disordered S(3)/AsO4tetrahedra are connected by O–H..O hydrogen bonds, to a zigzag chains running in theb-direction. These chains are, in turn, bonded to one another by disordered hydrogen bridges O–H..H–O, to give a planar structure, with hydrogen-bonded sheets, laying parallel to (1 0 0). Each disordered tetrahedron is linked to a tetrahedron neighbouring S(2)O4by ordered hydrogen bonds. Broader peaks in IR spectrum of the title material support the assumption of disordered structure. Thermal analysis of the superprotonic transition in Rb3(HSO4)2.5(H2AsO4)0.5showed that the transformation to the high-temperature phase occurs by one-step process at 404 K. Thermal decomposition of this compound takes place at much higher temperatures, with an onset of approximately 473 K. [ABSTRACT FROM AUTHOR]

We calculate the spontaneous polarization as a function of temperature for a mixed crystal ofclose to the tricritical point. This calculation of the spontaneous polarization is performed using the effective field approximation for the dipolar () and higher order (quadrupolar and octopolar) interactions for the mixed system ofat concentrations fromto. Our calculations show that as thedecreases with increasing the concentrationx, first order (discontinuous) transition which occurs at low concentrationsbecomes tricriticaland then the second order (continuous) transitionin. Dipolar and also higher order (quadrupolar and octopolar) interactions are needed to explain the mechanism of ferroelectric – paraelectric transition in. [ABSTRACT FROM PUBLISHER]

Rb2ZnI4shows phase transitional anomalies at about 4 K and about 62 K in the temperature dependence of the dielectric constant. To investigate those, the mixed systems (Rb1-xKx)2ZnI4and Rb2Zn1-xCdxI4were prepared by both evaporation from the aqueous solution and Czochralski method from the melt. Dielectric constant, spontaneous polarization and thermal expansion measurements were performed for such mixed systems. For (Rb1-xKx)2ZnI4, the phase diagram was completed over full range of concentration x. [ABSTRACT FROM PUBLISHER]

The Norwegian physicist Lars Vegard studied with William H. Bragg in Leeds and then with Wilhelm Wien in Würzburg. There, in 1912, he heard a lecture by Max Laue describing the first X-ray diffraction experiments and took accurate notes which he promptly sent to Bragg. Although now remembered mainly for his work on the physics of the aurora borealis, Vegard also did important pioneering work in three areas of crystallography. He derived chemical insight from a series of related crystal structures that he determined, Vegard's Law relates the unit-cell dimensions of mixed crystals to those of the pure components, and he determined some of the first crystal structures of gases solidified at cryogenic temperatures. [ABSTRACT FROM AUTHOR]

Atomistic simulations in the framework of the density functional theory have been used to model morphologic and vibrational properties of lithium niobate–lithium tantalate mixed crystals as a function of the [Nb]/[Ta] ratio. Structural parameters such as the crystal volume and the lattice parametersaandcvary roughly linearly from LiTaO3to LiNbO3, showing only minor deviations from the Vegard behavior. Ourab initiocalculations demonstrate that the TO1, TO2and TO4vibrational modes become harder with increasing Nb concentration. TO3becomes softer with increasing Nb content, instead. Furthermore, the investigated zone centerA1-TO phonon modes are characterized by a pronounced stoichiometry dependence. Frequency shifts as large as 30 cm−1are expected as the [Nb]/[Ta] ratio grows from 0 to 1. Therefore, spectroscopic techniques sensitive to theA1modes (such as Raman spectroscopy), can be employed for a direct and non-destructive determination of the crystal composition. [ABSTRACT FROM AUTHOR]

Temperature dependences of dielectric permittivity ϵ33, piezoelectric constant d36and elastic compliance S66of K1-x(NH4)xH2PO4ferro – antiferroelectric (FE - AFE) mixed crystals have been studied within temperature range 30 – 300 К. It was found a considerable contribution of the strain component x6to polarization P3near the FE transition temperature due to piezoelectric effect. Piezoelectric contribution to dielectric response in the vicinity AFE phase transition is weaker. It leads, in particular, to difference in the both shapes and positions of ϵ33and S66anomalies for K0,25(NH4)0,75H2PO4single crystal near the transition temperature. [ABSTRACT FROM PUBLISHER]

Cu6PS5I1  −   x Cl x mixed crystals were grown using chemical vapour transport. Isoabsorption studies of optical absorption edge and optical polarization measurements were performed in the temperature range 77–320 K. The influence of anionic I → Cl substitution on the phase transitions in Cu6PS5I1  −   x Cl x mixed crystals is studied. Compositional dependence of the phase-transition temperatures is obtained and the x,T-diagram for Cu6PS5I1  −   x Cl x mixed crystals is constructed. [ABSTRACT FROM PUBLISHER]

Strontium Titanate (SrTiO3), the most studied and well known quantum paraelectric since sixty years ago, results in a typical ferroelectric when substituting 16O by 18O. An effective field approach including quantum considerations of zero point energy explains satisfactorily the behavior of different ferroelectric-quantum paraelectric mixed systems. The isotopic strontium titanate SrTi (16O1-x 18Ox)3 can then be modelled as a mixed system with a critical composition (xc = 0.33) at which a crossover between ferroelectric and quantum paraelectric behavior takes place. A discussion is made in terms of dipole interaction strength for both isotopes. [ABSTRACT FROM PUBLISHER]

The dielectric properties of mixed Cu6PS5(Ix,Br1-x) crystals were investigated in wide frequency (20 Hz – 1 MHz) and temperature regions (120 K–300 K). Similar to the pure Cu6PS5Br and Cu6PS5I, the mixed Cu6PS5(Ix,Br1-x) exhibit two phase transitions - at higher temperatures feroelastic one and at lower temperatures a superionic phase transition. The ferroelastic phase transition temperature in mixed Cu6PS5(Ix,Br1-x) decreases from 273 K to 268 K while the superionic phase transition temperature increases 156 K to 166 K, with increasing bromine concentration. The ionic contribution to the total conductivity was separated from the electronic contribution by calculating the distribution of relaxation times from impedance spectra. [ABSTRACT FROM PUBLISHER]

The z(xy)-z Raman spectra of KDP/DKDP mixed crystals of the hydrogen and deuterium vibrations have been well reproduced by using a simple addition of KDP and DKDP spectra. The reciprocal half width γ-1 of the forbidden ν4 mode in x(zz)y Raman spectra in the paraelectric phase increases with increasing deuterium concentration just in the same way as the ferroelectric phase transition temperature Tc. These results indicate that the local distortion of PO4 tetrahedron is strongly correlated with the Tc in these hydrogen-bonded ferroelectrics. [ABSTRACT FROM AUTHOR]

Mixed crystals of NaBr and KBr were prepared from melt and physically characterized. Bulk composition of the crystals was estimated using the measured density values. X-ray diffraction analysis indicates the existence of two phases in the mixed crystals. Thermal parameters determined from the X-ray powder diffraction data are found to vary nonlinearly with bulk composition. DC and AC electrical measurements were carried out at various temperatures. The results indicate that the electrical parameters increase with the increase in temperature and vary nonlinearly with the bulk composition. Activation energies and mean jump frequencies were also determined. [ABSTRACT FROM AUTHOR]

In order to search for Pb-free relaxor substances and to define relaxor behaviour, a theoretical aspect is presented from not only microscopic but also phenomenological viewpoint. In order-disorder type mixed crystals, the microscopic approach is attempted under conditions similar to those for relaxor perovskite-type oxides. Basing on the theory for the precursor to glass state, two kinds of technique of X-ray diffuse scattering (static properties) and quadrupole perturbed nuclear magnetic resonance (NMR-NQR) (dynamic properties) are discussed in ferroelectric (FE) -- antiferroelectric (AFE) mixed crystals of Rb1-x(NH4)xH2PO4. After investigating both boundary regions between FE and glass (G) phases, and between AFE and G phases, relaxor-like behaviours as a large dispersion in dielectric constants are found in the AFE-G phase boundary region where the gradual growth of wave number to make the energy minimum and a discontinuous broad NMR-NQR spectrum appear in quite different forms from those of the FE-G phase boundary region. On the other hand, in perovskite-oxides, the conditions for relaxor appearance are discussed within the phenomenological theory by comparing with the microscopic analysis in hydrogen-bonded systems. [ABSTRACT FROM AUTHOR]

We have grown (NaCl)x (NaBr)y−x (NaI)1−y crystals for various values of x and y by the melt method. Densities and refractive indices of all the grown crystals were determined and used for the estimation of composition in the crystal. Lattice parameters were determined from the X-ray powder diffraction data. DC and AC measurements were done at various temperatures ranging from 40 to 150°C. Activation energies were also estimated. The bulk composition has complicated influences on the electrical properties. [ABSTRACT FROM AUTHOR]

Multiphased mixed crystals were grown by the melt method, for the first time, using the miscible alkali halides, namely, NaBr and KCl. X-ray powder diffraction measurements indicate the existence of multiple phases and mostly of ternary mixed alkali halides. Density and refractive index were measured and the composition was determined. Results are reported. [ABSTRACT FROM AUTHOR]

Ongoing studies of the RbHSeO4–RbH2PO4 system, aimed at developing novel proton conducting solids, resulted in the new compound Rb2(HSeO4)(H2PO4) (dirubidium hydrogenoselenate dihydrogenophosphate). Single-crystal X-ray diffraction (performed at room temperature) revealed Rb2(HSeO4)(H2PO4) to crystallize in space group P 21/ n with lattice parameters a &ThickSpace;=&ThickSpace;7.514 (3)&ThickSpace;Å, b &ThickSpace;=&ThickSpace;7.658 (2)&ThickSpace;Å, c &ThickSpace;=&ThickSpace;7.696 (3)&ThickSpace;Å and β&ThickSpace;=&ThickSpace;101.20 (3)°. The compound has a unit-cell volume of 434.4 (2)&ThickSpace;Å 3 and two formula units per cell, giving a calculated density of 3.149. Six non-H atoms and three H atoms were located in the asymmetric unit, with SeO4 and PO4 groups randomly arranged on the single tetrahedral anions site. Refinement using all observed reflections yielded residuals of 0.0971 and 0.0438 based on F 2 and F values, respectively. Anisotropic temperature factors were employed for all six non-H atoms and isotropic temperature factors for the three H atoms. The structure contains zigzag chains of hydrogen bonded anion tetrahedra that extend in the [010] direction. Each tetrahedron is additionally linked to a tetrahedron neighbouring chain to give a planar structure with hydrogen-bonded sheets lying parallel to The rubidium atom is coordinated by nine oxygen atoms with Rb–O range from 2.868 (4) to 3.364 (5)&ThickSpace;Å. The infrared spectra of the new compound Rb2(HSeO4)(H2PO4) recorded at room temperature in the frequency range 4000–400&ThickSpace;cm -1 , confirm the presence of and groups in the same crystal. Differential scanning calorimetry traces show two phase transitions at 382 and 665&ThickSpace;K in this material. [ABSTRACT FROM AUTHOR]

The analysis of dielectric and polarization properties of mixed ferroantiferroelectric crystals (1 -x )KDP-xADP and related systems has been performed for broad range of concentration x. The problems concerning the composition effect on spontaneous polarization, diffuseness of phase transitions, dynamics of proton glass transition and phase coexistence are discussed. [ABSTRACT FROM AUTHOR]

By X-ray diffraction structure determination, together with Raman scattering, optical birefringence and low frequency dielectric measurements, ferrielectric phase transitions in regions of trigonal and monoclinic phases on a temperature—concentration diagram of CuInP2(SexS1-x)6 mixed crystals are investigated. The phase transitions temperatures rapidly decrease and related anomalies smear at deviation from pure compounds. In a middle interval of concentrations a dipole ordering obviously has peculiar character. [ABSTRACT FROM AUTHOR]

Influence of NH4→Cs substitution has been studied in the mixed Cs 1-x (NH 4 ) x H 2 PO 4 crystals system by means of dielectric measurements. The x-T phase diagram was determined: for ammonium concentrations up to 0.1 the system has a monoclinic paraelectric phase with a transition into a ferroelectric phase whose temperature increases with increasing ammonium concentration. For ammonium concentration 0.4 to 1.0 the system shows a tetragonal paraelectric phase and a transition into an antiferroelectric phase. No solid solutions with concentrations between 0.1 and 0.4 could be grown. The system was further studied with the quasi-one-dimensional Ising model and the three-dimensional anisotropic Ising model. [ABSTRACT FROM AUTHOR]