Search

The metal–insulator transition driven by electronic correlations is one of the most fundamental concepts in condensed matter. In mixed-valence compounds, this transition is often accompanied by charge ordering (CO), resulting in the emergence of complex phases and unusual behaviors. The famous example is the archetypal mixed-valence mineral magnetite, Fe3O4, exhibiting a complex charge-ordering below the Verwey transition, whose nature has been a subject of long-time debates. In our study, using high-resolution X-ray diffraction supplemented by resistance measurements and DFT+DMFT calculations, the electronic, magnetic, and structural properties of recently synthesized mixed-valence Fe4O5are investigated under pressure to ∼100 GPa. Our calculations, consistent with experiment, reveal that at ambient conditions Fe4O5is a narrow-gap insulator characterized by the original Verwey-type CO. Under pressure Fe4O5undergoes a series of electronic and magnetic-state transitions with an unusual compressional behavior above ∼50 GPa. A site-dependent collapse of local magnetic moments is followed by the site-selective insulator-to-metal transition at ∼84 GPa, occurring at the octahedral Fe sites. This phase transition is accompanied by a 2+ to 3+ valence change of the prismatic Fe ions and collapse of CO. We provide a microscopic explanation of the complex charge ordering in Fe4O5which “unifies” it with the behavior of two archetypal examples of charge- or bond-ordered materials, magnetite and rare-earth nickelates (RNiO3). We find that at low temperatures the Verwey-type CO competes with the “trimeron”/“dimeron” charge ordered states, allowing for pressure/temperature tuning of charge ordering. Summing up the available data, we present the pressure–temperature phase diagram of Fe4O5.

Structural instability has a strong influence on the understanding of superconductivity in iron-containing 122 phases. Similar to the 122 iron-based high-temperature superconductors, the intermetallic compound BaNi2Ge2undergoes an orthorhombic-to-tetragonal structural phase transition. The compound was prepared by arc-melting mixtures of the elements under an argon atmosphere. Single crystals were obtained by a special heat treatment in a welded tantalum ampule. The crystal structure of the compound was investigated by powder and single-crystal X-ray diffraction. Differential thermal analysis of BaNi2Ge2showed a reversible phase transition at ca. 480 °C. In situ temperature-dependent synchrotron powder X-ray diffraction studies revealed that below 480 °C the crystal structure of BaNi2Ge2is orthorhombic [own structure type, space group Pnma, a= 8.3852(4) Å, b= 11.3174(8) Å, and c= 4.2902(9) Å at 30 °C] and the high-temperature phase above 510 °C belongs to the tetragonal ThCr2Si2-type structure [space group I4/mmm, a= 4.2664(1) Å, and c= 11.2537(3) Å at 510 °C]. The reversible first-order low-temperature ↔ high-temperature phase transition around 480 °C is associated with distortion of the [Ni2Ge2] layer of low-temperature modification. The anisotropy of thermal expansion of the unit cell in BaNi2Ge2was analyzed. The crystal chemistry and chemical bonding are discussed in terms of linear muffin-tin orbital band structure calculations and a topological analysis using the electron localization function. In related compounds, the level of distortion of the uncollapsed tetragonal ThCr2Si2-type structure depends on the valence electron count (VEC).

The article addresses a practicable and economic low-temperature method of TiO2synthesis, which allows us in a specific manner to influence structure-sorption characteristics and photocatalytic activity of samples not at the expense of the change of temperature of finite treatment, but rather by way of varying additions of the precipitant and modifier. This method helped obtain nanodisperse TiO2with a developed specific area of the surface and high photocatalytic activity with respect to dyes of the anionic and cationic types. Individually obtained TiO2samples display activity even higher than commercial products.

The main objective of this study is to improve the ultrasound image by employing a new algorithm based on transducer array element beam pattern correction implemented in the synthetic transmit aperture (STA) method combined with emission of mutually orthogonal complementary Golay sequences. Orthogonal Golay sequences can be transmitted and received by different transducer elements simultaneously, thereby decreasing the time of image reconstruction, which plays an important role in medical diagnostic imaging.

The paper presents an overview of theoretical aspects of ultrasound image reconstruction techniques based on the circular Radon transform inversion. Their potential application in ultrasonography in a similar way as it was successfully done in the x-ray computer tomography is demonstrated. The methods employing Radon transform were previously extensively explored in the synthetic aperture radars, geophysics, and medical imaging using x-ray computer tomography. In this paper the main attention is paid to the ultrasound imaging employing monostatic transmit-receive configuration. Specifically, a single transmit and receive omnidirectional source placed at the same spatial location is used for generation of a wide-band ultrasound pulse and detection of back-scattered waves. The paper presents derivation of the closed-form solution of the CRT inversion algorithms by two different approaches: the range-migration algorithm (RMA) and the deconvolution algorithm (DA). Experimentally determined data of ultrasound phantom obtained using a 32-element 5 MHz linear transducer array with 0.48 mm element pitch and 0.36 mm element width and 5 mm height, excited by a 2 sine cycles burst pulse are used for comparison of images reconstructed by the RMA, DA, and conventional synthetic aperture focusing technique (SAFT). It is demonstrated that both the RMA and SAFT allow better lateral resolution and visualization depth to be achieved as compared to the DA approach. Comparison of the results obtained by the RMA method and the SAFT indicates slight improvement of the lateral resolution for the SAFT of approximately 1.5 and 1.6% at the depth of 12 and 32 mm, respectively. Concurrently, however, the visualization depth increase for the RMA is shown in comparison with the SAFT. Specifically, the scattered echo amplitude increase by the factor of 1.36 and 1.12 at the depth of 22 and 32 mm is demonstrated. It is also shown that the RMA runs about 30% faster than the SAFT and about 12% faster than the DA method

Oxygen surface exchange and oxygen chemical diffusion coefficients of LaNi0.4Fe0.6O3−δceramics are determined via conductivity relaxation method after stepwise change of temperature in the range of 700–950 °C in air and Ar/O2gas flow at oxygen partial pressures ($$p_{O_2}$$) of 4 Pa, 18 Pa, 37 Pa, 47 Pa and 59 Pa. The highest conductivity (about 160 S·cm−1) is found at 950 °C in air. No oxygen exchange (δ= 0) below 700 °C is observed in the investigated $$p_{O_2}$$range. The oxygen exchange coefficients determined in reduction mode are higher than those determined in oxidation mode. This is explained by clusterization of oxygen vacancies on the surface of the sample investigated in oxidation mode. The opposite tendency is found for chemical diffusion coefficients. Unlike surface, the oxygen vacancies of the volume region are probably not clustered and have predetermined the higher oxygen diffusion mobility of the sample treated in oxidation mode.

At lower mantle conditions, subducted mid oceanic ridge basalts (MORB) will crystallize more than 20 vol% of an aluminum-rich phase, which is referred to generally as the new aluminum (NAL) phase. Given that a significant proportion of the lower mantle may be comprised of subducted crust, the NAL phase may contribute to the bulk elastic properties of the lower mantle. In this study we report for the first time the structure, Raman spectrum and elasticity of single crystals of Na0.41[Na0.125Mg0.79Al0.085]2[Al0.79Si0.21]6O12NAL phase, synthesized at 2260 °C and 20 GPa. The single-crystal structure refinement of NAL, which is consistent with the space group P63/m, reveals dynamic disorder of Na atoms along channels within the structure. The elastic tensor was experimentally determined at ambient conditions by Brillouin scattering spectroscopy. The elastic modulii obtained from the Voigt- Reuss-Hill approximation using the elastic constants determined in this study are KS= 206 GPa and μ = 129 GPa, whereas the isotropic compressional and shear sound velocities are vP= 9.9 km/s and vS= 5.8 km/s. The NAL phase is elastically anisotropic, displaying 13.9% compressional and shear wave anisotropy. Elastic constants as well as Raman active modes of NAL have also been calculated using density-functional theory and density-functional perturbation theory.

Primary pressure determinations involve the measurement of pressure without recourse to secondary standard materials. These measurements are essential for ensuring the accuracy of pressures measured in gasketed high‐pressure devices. In this study, the wavelength of optical fluorescence bands and the density of single crystal Sm‐doped yttrium aluminum garnet Y3Al5O12(Sm:YAG) have been calibrated as a primary pressure scale up to 58 GPa. Absolute pressures were obtained by integrating the bulk modulus determined via Brillouin spectroscopy with respect to volumes measured simultaneously by X‐ray diffraction. A third‐order Birch‐Murnaghan equation of state of Sm:YAG yields V0= 1735.15(26) Å3, KT0= 185(1.5) GPa, and K`= 4.18(5). The accompanied pressure‐induced shifts of the fluorescence lines Y1 and Y2 of Sm:YAG were calibrated to the primary pressure, thus creating a highly accurate fluorescence pressure scale. These shifts are described as P= (A/B) * {[1 + (Δλ/λ0)]B− 1} with A= 2089.91(23.04), B= −4.43(1.07) for Y1, and A= 2578.22(48.70), B= −15.38(1.62) for Y2 bands, where ∆λ= λ− λ0, λand λ0are wavelengths in nanometer at pressure and ambient conditions. The sensitivity in the pressure determination of the Sm:YAG fluorescence shift is 0.32 nm/GPa, which is identical to that of the ruby scale. Sm:YAG can be considered elastically isotropic up to 58 GPa, implying insensitivity of the determined pressure to the crystallographic orientation under nonhydrostatic or quasi‐hydrostatic conditions. The Sm:YAG fluorescence shift is apparently also independent of crystallographic orientation, in contrast to that of ruby. Since the Y fluorescence band of Sm:YAG is insensitive to temperature changes, this material is highly suitable for the measurement of pressure at elevated temperatures. Elastically isotropic fluorescence pressure sensorStatic primary fluorescence pressure scaleEnsuring the accuracy of pressures measured in gasketed high pressure devices

Nominally hydrous high-pressure silicate phases such as the superhydrous phase B are of considerable importance for the understanding of the water-cycle between the surface and the interior of the Earth. This study tackles the controversial issue of hydrogen positions in superhydrous phase B, a phase believed to be potentially stable in cold subducting ultramafic slabs. To investigate the nature of hydrogen incorporation into the structure of superhydrous phase B, neutron powder diffraction experiments have been performed. A structural model based on Pnn2 symmetry has been used for the analysis of the data, which is consistent with earlier spectroscopic studies. Application of Fourier synthesis with subsequent analyses of difference nuclear density maps and Rietveld fits reveal two distinct positions for deuterium, at 4c (0.194, 0.052, 0.596) and at 4c (0.186, 0.119, 0.388). This unambiguously shows that deuterium lies within large channels, which are formed between the edgeshared octahedra and vertex-linked tetrahedra along the b-axis of the structure. These results contrast with recent polarized single-crystal infrared spectroscopy studies where the position of one of two H atoms was estimated to lie close to the octahedral edge of an MgO6octahedron, thereby leaving the large structural channel empty.

Crystal structure,thermal expansion, oxygen non-stoichiometry, electrical conductivity and diffusion characteristics of two analogous LaFe0.7Ni0.3O3‑d and PrFe0.7Ni0.3O3‑d compositions were investigated depending on temperature (201000 °C) and oxygen partial pressure (0.6–21000 Pa). The found oxygen diffusion and oxygen exchange coefficients for the both compositions at similar conditions are near to each other and varied in the range of 110‑7110‑5 cm2s‑1 and 510‑6110‑4 cms‑1, respectively.

In situ synchrotron X-ray powder diffraction measurements using a Paris-Edinburgh pressure cell were performed to investigate the nature of the high-pressure breakdown reaction of magnetite (Fe3O4). Refinement of diffraction patterns reveals that magnetite breaks down via a disproportionation reaction to Fe4O5and hematite (Fe2O3) rather than undergoing an isochemical phase transition. This result, combined with literature data indicates (1) that this reaction occurs at ~9.5-11 GPa and 973-1673 K, and (2) these two phases should recombine at yet higher pressures to produce an h-Fe3O4phase.

The thermal expansion of anhydrous Mg2SiO4wadsleyite and forsterite was comprehensively studied over the temperature ranges 297-1163 and 297-1313 K, respectively, employing X-ray powder diffraction. Experiments were carried out with two separately synthesized samples of wadsleyite (numbered z626 and z627), for which room temperature unit-cell volumes differed by 0.05%, although the determined thermal expansions were identical within error. The high-temperature thermal expansions of wadsleyite and forsterite were parameterized on the basis of the first-order Grüneisen approximation using a Debye function for the internal energy. Values for hypothetical volume at T = 0 K, Debye temperature and Grüneisen parameter are 536.86(14) Å3, 980(55) K, 1.28(2) and 537.00(13) Å3, 887(50) K, 1.26(1) for z626 and z627, respectively, with the bulk modulus fixed to a literature determination of 161 GPa. For forsterite, the respective values are 288.80(2) Å3, 771(9) K, and 1.269(2) with a constrained bulk modulus of 125 GPa. These quantities are in good agreement with literature values obtained independently from sound velocity and heat capacity measurements, giving strong support to the applicability of Grüneisen theory in describing the thermal expansion of wadsleyite and forsterite. In addition, high-temperature structural variations were determined for wadsleyite from Rietveld analysis of the X-ray diffraction data. The pronounced anisotropy in thermal expansion of wadsleyite with a more expandable c-axis, similar to the compressional anisotropy, arises from specific features of the crystal structure consisting of the pseudolayers of MgO6octahedra parallel to the a-b plane with cross-linking Si2O7dimers along the c-axis. Although anisotropic compression and expansion originate from the same structural features, the details of structural changes with pressure differ from those caused by temperature. The longest Mg-O bonds, which are roughly parallel to the c-axis in all three octahedral sites of wadsleyite, dominate the compression, but these bonds do not exhibit the largest expansivities.

Optimization of the Multi-element Synthetic Transmit Aperture Method for Medical Ultrasound Imaging ApplicationsThe paper presents the optimization problem for the multi-element synthetic transmit aperture method (MSTA) in ultrasound imaging applications. The optimal choice of the transmit aperture size is made as a trade-off between the lateral resolution, penetration depth and the frame rate. Results of the analysis obtained by a developed optimization algorithm are presented. The maximum penetration depth and lateral resolution at given depths are chosen as optimization criteria. The results of numerical experiments carried out in MATLAB® using synthetic aperture data of point reflectors obtained by the FIELD II simulation program are presented. The visualization of experimental synthetic aperture data of a tissue mimicking phantom and in vitromeasurements of the beef liver performed using the SonixTOUCH Research system are also shown.

AbstractThe paper presents the theoretical and experimental study of synthetic transmit aperture (STA) method combined with Golay coded transmission for medical ultrasound imaging applications. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution.In the work the 128-element linear transducer array with 0.3 mm pitch excited by the 8 and 16-bits Golay coded sequences as well as a one cycle at nominal frequencies 4 MHz were used. The comparison of 2D ultrasound images of the tissue mimicking phantoms is presented to demonstrate the benefits of coded transmission. The image reconstruction was performed using synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.

Multi-Element Synthetic Transmit Aperture in Medical Ultrasound ImagingSynthetic aperture (SA) technique is a novel approach to present day commercial systems and has previously not been used in medical ultrasound imaging. The basic idea of SA is to combine information acquired simultaneously from all directions over a number of emissions and to reconstruct the full image from these data.The paper presents the multi-element STA (MSTA) method for medical ultrasound imaging. The main difference with the STA approach is the use of a few elements in the transmit mode in contrast to a single element aperture. This allows increasing the system frame rate, decreasing the number of emissions, and provides the best compromise between the penetration depth and lateral resolution. Besides, a modified MSTA is proposed with a corresponding RF signal correction in the receive mode, which accounts for the element directivity property.In the experiments a 32-element linear transducer array with 0.48 mm inter-element spacing and a burst pulse of 100 ns duration were used. Two elements wide transmission aperture was used to generate an ultrasound wave covering the full image region. The comparison of 2D ultrasound images of a tissue mimicking phantom obtained using the STA and MSTA methods is presented to demonstrate the benefits of the second one.

The compounds Li8EN2with E= Se, Te were obtained in form of orange microcrystalline powders from reactions of Li2Ewith Li3N. Single crystal growth of Li8SeN2additionally succeeded from excess lithium. The crystal structures were refined using single‐crystal X‐ray diffraction as well as X‐ray and neutron powder diffraction data (I41md, No. 109, Z= 4, Se: a= 7.048(1) Å, c= 9.995(1) Å, Te: a= 7.217(1) Å, c= 10.284(1) Å). Both compounds crystallize as isotypes with an anionic substructure motif known from cubic Laves phases and lithium distributed over four crystallographic sites in the void space of the anionic framework. Neutron powder diffraction pattern recorded in the temperature range from 3 K to 300 K and X‐ray diffraction patterns using synchrotron radiation taken from 300 K to 1000 K reveal the structural stability of both compounds in the studied temperature range until decomposition. Motional processes of lithium atoms in the title compounds were revealed by temperature dependent NMR spectroscopic investigations. Those are indicated by significant changes of the 7Li NMR signals. Lithium motion starts for Li8SeN2above 150 K whereas it is already present in Li8TeN2at this temperature. Quantum mechanical calculations of NMR spectroscopic parameters reveal clearly different environments of the lithium atoms determined by the electric field gradient, which are sensitive to the anisotropy of charge distribution at the nuclear sites. With respect to an increasing coordination number according to 2 + 1, 3, 3 + 1, and 4 for Li(3), Li(4), Li(2), and Li(1), respectively, the values of the electric field gradients decrease. Different environments of lithium predicted by quantum mechanical calculations are confirmed by 7Li NMR frequency sweep experiments at low temperatures.

The solid solution Sr2Sc1+xRe1–xO6with a monoclinicperovskitelike structure has been prepared with the composition range 0 ≤ x ≤ 0.333. When x ≤ 0, other phases compete with the formation of Sr2Sc1+xRe1–xO6. Crystallographic details of Sr2ScReO6x= 0 were investigated by neutron and synchrotron powder diffraction in the temperature range 10–1153 K. Upon cooling, Sr2ScReO6undergoes structural phase transitions: from cubic Fm3mto tetragonal I4mat ca. 800 K and from tetragonal I4mto monoclinic P21nat ca. 350 K, and a twophase field monoclinic P21n+ tetragonal I4m was observed below 75 K. The latter transition coincides with a magnetic rearrangement from the paramagnetic to antiferromagnetic state. Compositions with x> 0 demonstrate no antiferromagnetic ordering.

Single-phase LaNi0.6Fe0.4O3-d and multiphase powder with nominal composition LaNi0.8Fe0.2O3 were prepared by solid state reactions method from initial simple oxides. It was shown that the conductivity of LaNi0.6Fe0.4O3-d is 2-3 times higher in comparison with LaNi0.8Fe0.2O3 at comparable conditions. Opposite to multiphase ceramics, LaNi0.6Fe0.4O3-d shows reversible behaviour during heating-cooling treatments up to 800-1000 degC in air and Ar/O2 gas flows at oxygen partial pressure 1-21000 Pa and can be recommended as cathode material for intermediate temperature SOFC.

AbstractThe structure of the copper(II) chloride complex with deuterated 1-ethyltetrazole has been investigated in the temperature range of 2–290 K using neutron and synchrotron X-ray powder diffraction. The compound was found to exhibit structural transformation at ca.180 K, without change of space group and main structural motif. At higher temperatures, the complex reveals positional disorder of the ethyl group, whereas no disorder is observed at lower temperatures. Temperature dependence of the lattice parameters, obtained from synchrotron X-ray data, showed main lattice changes at the transformation, explained by structural features of the complex. From the magnetic measurements, the effect of the disorder on paramagnetic behaviour of the compound was found. Detailed structural data of the compound at 2 and 290 K, obtained from neutron powder diffraction data, are reported.

The thermal stability of cathodes charged to different lithium contents was studied by synchrotron diffraction and differential thermal analysis. Both olivine-like phases and appearing during the delithiation of are unstable upon heating, and decompose readily in the range . The decomposition of lithium-poor phases leads to gas evolution and the crystallization of . The role of carbon present in the electrochemically delithiated samples is discussed. The significantly lower stability of charged in comparison with is a serious challenge for the application of this material in rechargeable Li-ion batteries.

Abstract: The ternary superionic conductor AgCuS was studied by means of inelastic neutron scattering at temperatures of 150 to 398 K. The experimental time-of-flight spectra were recalculated into the generalized phonon density of states G(ɛ) in an incoherent approximation. It is shown that G(ɛ) of AgCuS has a nontrivial temperature dependence over the low-energy range. The relation between the temperature dependence of G(ɛ) and the existence of a low-energy mode in AgCuS is discussed.

Structural features of Li-extraction from the LiCrMnO4cathode material in Li-electrochemical cells were investigated by in situ synchrotron powder diffraction and completed by ex situ neutron powder diffraction and magnetization measurements on delithiated products. The observed diffraction patterns reveal that both Li-extraction during the cell charge up to 5.15 V and the following Li-insertion upon the discharge down to 3.2 V vs. Li+/Li are one-phase solid-solution processes. According to the Rietveld structure refinement Li atoms were completely removed from the tetrahedral 8asite during the cell charge with the C/10 rate. However, only about 40% Li atoms were inserted during the cell discharge with the same rate. The unit cell parameter aand the average metal−oxygen distance (Cr,Mn-O) show non-linear dependence on the lithium content upon extraction, with the slope changing at 4.9 V and manifesting a change in the mechanism of redox behavior. While the first step between 3 V and 4.9 V is presumably accompanied by the oxidation of Cr3+to Cr4+, the charging above 4.9 V requires a further oxidation of Cr4+toward Cr6+. The paramagnetic effective moment of LixCrMnO4compounds changes non-monotonously with decreasing Li-content.

A modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imaging with RF echoes correction taking into account the influence of the element directivity is presented. The property is significant as the element width becomes commensurable with the wavelength of the emitted signal. The angular dependence of the radiation efficiency of the transmit/receive aperture is obtained from exact solution of the corresponding mixed boundary-value problem for periodic baffle system, modeling the transducer array. It is evaluated at the nominal frequency of the excitation signal and is implemented in the developed MSTA algorithm as apodization weights calculated for each imaging point and all combinations of the transmit/receive apertures. The performance of developed method is tested using FIELDII simulated synthetic aperture data of the point reflectors to estimate the visualization depth and lateral resolution. Besides, a FIELDII simulated and measurement data of cyst phantom are used for qualitative assessment of the imaging contrast. Comparison of the results obtained by the modified and conventional MSTA algorithms is given which reveals considerable improvement of the image quality in the area neighboring to the transducer's aperture, and increase of the visualization depth at the cost of slight degradation of lateral resolution near the transducer face.

Li1.0MoO2(I), Li0.91MoO2(II), and Li0.75MoO2(III) are synthesized by solid state reactions of stoichiometric mixtures of Li2MoO4, Mo, and MoO3(alumina crucibles, 1223 K, 20 h) and characterized by single crystal XRD, powder XRD, XPS, and electrochemical measurements.

The structural features of Sr2CoIrO6‐δin which the oxygen deficiency can be well controlled and reversibly varied up to δ = 0.33, depend on both temperature and oxygen content and are determined by synchrotron and neutron powder diffraction.

The title compound is prepared from stoichiometric mixtures of Li2MoO4, MoO3, and V2O3(Ar, silica tube, 813 K, 30 h) and characterized by single crystal XRD, electrochemical measurements, XPS, and magnetic measurements.

The title compounds are prepared from mixtures of Li2E (E: Se, Te) and Li3N (Ta ampules, 1023 K).

Single-phase LaNi0.6Fe0.4O3-δ and multiphase powder with nominal composition LaNi0.8Fe0.2O3 were prepared by solid state reactions method from initial simple oxides. It was shown that the conductivity of LaNi0.6Fe0.4O3-δ is 2-3 times higher in comparison with LaNi0.8Fe0.2O3 at comparable conditions. Opposite to multiphase ceramics, LaNi0.6Fe0.4O3-δ shows reversible behaviour during heating-cooling treatments up to 800-1000 °C in air and Ar/O2 gas flows at oxygen partial pressure 1-21000 Pa and can be recommended as cathode material for intermediate temperature SOFC.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The thermal stability of LiCoPO4cathodes charged to different lithium contents was studied by synchrotron diffraction and differential thermal analysis. Both olivine-like phases LizCoPO4(z=0.6)and CoPO4appearing during the delithiation of LiCoPO4are unstable upon heating, and decompose readily in the range 100–200°C. The decomposition of lithium-poor phases leads to gas evolution and the crystallization of Co2P2O7. The role of carbon present in the electrochemically delithiated samples is discussed. The significantly lower stability of charged LiCoPO4in comparison with LiFePO4is a serious challenge for the application of this material in rechargeable Li-ion batteries.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.