Crystal Volume Research Articles

The effect of selenium supplementation on cystine crystal volume in patients with cystinuria

The effect of selenium supplementation on cystine crystal volume in patients with cystinuria

HOST-GUEST INTERACTIONS FACILITATED BY CHALCOGEN BONDING WITHIN SELENADIAZOLE FUNCTIONALISED PORPHYRIN NANOTUBES.

The structural rigidity of tetrakis(4-pyridyl)porphyrin (TPyP) has been utilised to prepare a robust novel porous coordination polymer of composition Cd2(TPyP)(sez)2 (TPyP = 5,10,15,20-tetra(4-pyridyl)porphyrin, sez = 1,2,5-benzoselenadiazole-5-carboxylate). The coordination polymer may be described as a hexagonal porphyrin nanotube (PNT) and has the potential to bind guest molecules through chalcogen bonding. Single crystal X-ray diffraction (SCXRD) data indicate an internal pore diameter ~9 Å which represents ~35% of the crystal volume. Immersion of the PNTs in solvents such as DMSO and CS2 result in the incorporation of these molecules within the nanotubes with chalcogen bonding between host and guest. The crystallographic guest-inclusion investigations are complemented by solid-state 77Se, 13C, 113Cd and 2H NMR studies which provide insights into dynamic behaviour. The porosity of the crystals was further explored using gas adsorption experiments, indicating the reversible uptake of CO2, CH4, H2 and N2. Structure-function relationships are clearly established from complementary crystallographic, NMR and adsorption investigations.

Double‐Walled Honeycomb‐Like Metal‐Organophosphonium Framework with High H2 Gas Adsorption Capacities

AbstractThis study successfully synthesized a new Metal‐Organic Framework (MOF) named CJLU−L2, which was constructed from phosphorus‐containing ligands and Co(II) ions. The structure revealed through single‐crystal X‐ray diffraction (SCXRD), features a double‐walled honeycomb‐shaped structure with a one‐dimensional channel of ~6.5 Å. According to the PLATON calculation, the pore volume per unit cell of CJLU−L2 was determined to be 6825.0 Å3, constituting 57.5 % of the total crystal volume (11874.9 Å3). The Brunauer‐Emmett‐Teller (BET) surface area of CJLU−L2 was determined to be 954 m2/g by N2 adsorption measurement at 77 K. The phase purity of CJLU−L2 was verified by powder X‐ray diffraction (PXRD) and infrared spectroscopy (IR), while its thermal stability was confirmed by thermogravimetric analysis (TGA). Hydrogen adsorption experiments demonstrate that CJLU−L2 exhibits a high hydrogen adsorption capacity, indicating significant potential for gas adsorption applications.

A model of freeze desalination for predicting salt concentration in ice using the laws of conservation of matter & mass

The assessment of freeze desalination (FD) efficiency is lagging behind due to the lack of an effective means of determining ice total dissolved solid (TDS). In this paper, an ice TDS prediction model was constructed by utilizing the law of conservation of matter (LCMat) and conservation of mass (LCMas) in the icing process. It was concluded that the average TDS ice crystals in any icing process was correlated with the TDS of the raw (concentrated) water at the starting of freezing, the salt mass change rate of the concentrate water, and the volume of ice crystals. A one-way FD test was carried out using the saltwater from South Xinjiang, and the exponential equation model and linear equation model of LCMat-LCMas were derived, and the simulation accuracy of LCMat-LCMas was verified by using the test data. The results show that the model has high prediction accuracy. The exponential equation model is suitable for predicting the ice TDS for ice with thickness within 15 cm, and the linear equation is suitable for predicting the ice crystal TDS for ice thicker than 15 cm. Further validation of the model accuracy is needed for larger cooled areas and icing thicknesses, and multidirectional icing processes.

Thermolysis of Cs9MO4 (M = In, Sc): Synthesis, Crystal Structure, Chemical Bonding, and Reactivity of the Subvalent Oxidometalates Cs7MO4 (M = In, Sc).

The cesium-poor alkali-metal suboxidometalates Cs7MO4 (M = In, Sc) were prepared from the respective cesium-rich suboxidometalates Cs9MO4 by thermolysis in a dynamic vacuum at temperatures below 150 °C. They crystallize in a new structure type, comprising isolated tetrahedral oxidometalate anions [MO4]5- immersed in a matrix of metallic cesium atoms. This structural separation into alternating ionic and metallic building units is typical for subvalent compounds. Cs7InO4 and Cs7ScO4 are isotypic and form mixed crystals Cs7(In1-xScx)O4 with statistic distribution of In and Sc atoms. All compounds were characterized by single crystal and powder X-ray diffraction. Calculations of the electronic structure with DFT methods corroborate the coexistence of anionic entities within a metallic matrix and give evidence of the subvalent nature of cesium atoms. Overall metallic behavior is a consequence of the equal volume fractions of metallic and ionic regions, allowing for percolation of the conduction electrons throughout the crystal volume. Differential thermoanalysis was employed to gain insight into the chemical conversion processes during the thermolysis reaction. The thermolytic decomposition of Cs9MO4 is a multistep process with, in some instances, reversible amorphization and recrystallization steps. Finally, the formation of ionic compounds is observed. The full decomposition of Cs9ScO4 yields the two new oxidoscandates Cs14Sc4O13 and Cs17Sc5O15 with tetrahedral [ScO4] units connected to chain fragments and the indium compound yields cesium oxidoindates with low-condensed [InO4] building units. The cesium-poor suboxidometalates Cs7MO4 themselves can serve as starting materials for the synthesis of further, new suboxidometalates, as they show a unique reactivity toward metals.

Dependence of the crystal structure on the d-units amount in semi-crystalline poly(lactic acid)

The study investigates the impact of the d-lactic acid units content on the crystallinity and crystal structure of commercial poly(lactic acid) (PLA) grades, which are copolymers of poly(l-lactic acid) (PLLA) containing a minor amount of d-units. As the d-units content increases, a detectable decrease in crystallinity was observed along with a simultaneous rise in mobile amorphous fraction (MAF) and a reduction in rigid amorphous fraction (RAF). The percentage of d-units was found not to significantly affect RAF thickness, suggesting that the d-units are not completely excluded from the crystals. The inclusion of d-units as defects in the PLA crystal lattice was confirmed by XRD analysis, which disclosed that the crystal phase gets gradually richer of d-units as the crystallization time evolves. FT-IR analysis proved that the incorporation of d-units in the crystal phase is promoted by the formation of local CH3···O=C interactions, similar to those massively active between PLLA and poly(d-lactic acid) (PDLA) in the stereocomplex. The establishment of these interactions leads to a contraction of the interplanar distances and a decrease in the crystal cell volume with increasing the crystallization time and the d-units percentage. In summary, the study proves that for PLA copolymers containing a d-units percentage at least up to about 8 %, d-units are included in the crystal lattice.

Structure-activity relationship, adsorption, and fenton-like catalytic oxidation capacity of iron-oxide nano-confined materials

In this study, iron-oxide was loaded into polystyrene macroporous microspheres containing sulfonate groups to prepare an environmental purification material with adsorption and Fenton-like oxidizing abilities. Iron-oxide is prone to inactivation due to reunion in the process of preparation and application, and this modification aimed to mitigate this problem. Subsequently, based on the microscopic characterization results and the effect on the treatment of methylene blue (MB) simulated wastewater, the structure-activity relationship of two key (OH− concentrations in precipitation solution and iron ion compositions in the impregnation solution) factors with the adsorption and catalytic oxidation ability of the iron-oxide nano-confined materials were explored. The results indicated that the samples both exhibited adsorption and catalytic oxidation capabilities. The removal efficiency of MB simulated wastewater can reached 95.3% after adsorption for 9 h, reaching 99.98% after catalytic oxidation for 6 h. In addition, the removal efficiency of the MB simulated wastewater exceeded 95% after 6 cycles. The concentration of OH− in precipitation solution could affect the volume of iron crystals on the carrier which affected the pore size of the sample and the adsorption capacity. It also influenced whether iron ions could be stably loaded inside the carrier, determining the conducting homogeneous or heterogeneous Fenton-like reactions and the stability of the samples. The composition of iron ions in the impregnating solution regulated the volume of the crystals and adsorption sites, which influenced the adsorption ability of the samples. In addition, the presence of Fe2+ could promote the progress of Fenton-like reactions. The identification results of the ROSs showed that •OH was the main free radical. The quenching experiment results showed that the contribution rate of •OH toward MB degradation reached 99.81%. In addition, the possible degradation pathways of MB were analyzed.

Deconstructing 3D growth rates from transmission microscopy images of facetted crystals as captured in situ within supersaturated aqueous solutions.

Here, a morphologically based approach is used for the in situ characterization of 3D growth rates of facetted crystals from the solution phase. Crystal images of single crystals of the β-form of l-glutamic acid are captured in situ during their growth at a relative supersaturation of 1.05 using transmission optical microscopy. The crystal growth rates estimated for both the {101} capping and {021} prismatic faces through image processing are consistent with those determined using reflection light mode [Jiang, Ma, Hazlehurst, Ilett, Jackson, Hogg & Roberts (2024 ▸). Cryst. Growth Des. 24, 3277-3288]. The growth rate in the {010} face is, for the first time, estimated from the shadow widths of the {021} prismatic faces and found to be typically about half that of the {021} prismatic faces. Analysis of the 3D shape during growth reveals that the initial needle-like crystal morphology develops during the growth process to become more tabular, associated with the Zingg factor evolving from 2.9 to 1.7 (>1). The change in relative solution supersaturation during the growth process is estimated from calculations of the crystal volume, offering an alternative approach to determine this dynamically from visual observations.

Layered Structure Modification of Sodium Vanadate through Ca/F Co‐Doping for Enhanced Energy Storage Performance

AbstractVanadate materials are promising for sodium‐ion batteries (SIBs) due to their low cost, high capacity, and high power characteristics enabled by vanadium's multiple oxidation states. However, their development is hindered by poor conductivity, suboptimal high‐rate performance, and limited cycle life. In this work, a layered structure modification strategy involving Ca/F co‐doping in sodium vanadate Na2CaV2O6F (CVF) is proposed to address these issues. Through a combination of experiments and density functional theory calculations, it is demonstrated that Ca/F synergies enhance the Na layer spacing in CVF, resulting in reduced crystal water content and volume shrinkage compared to Na2V2O6 (NVO). Additionally, Ca/F incorporation significantly mitigates the diffusion potential of Na+ within the material framework. The unmodified CVF sample exhibits a high reversible capacity of 220 mAh g−1 at 10 mA g−1 and an excellent rate capacity of 65.78 mAh g−1 at 400 mA g−1. Furthermore, the cathode material maintains a capacity of up to 138 mAh g−1 at 200 mA g−1 and retains 104.88 mAh g−1 after 100 cycles within the voltage range of 1.5−4.0 V. These findings enhance the understanding of the crystal structure of NVO cathode materials and pave the way for the rational design of high‐quality vanadate cathodes for SIBs.

Transcriptional activation of PINK1 by MyoD1 mediates mitochondrial homeostasis to induce renal calcification in pediatric nephrolithiasis

This study aims to uncover the molecular mechanisms underlying pediatric kidney stone formation induced by renal calcium deposition by utilizing high-throughput sequencing data to reveal the regulation of PINK1 by MyoD1. We performed transcriptome sequencing on peripheral blood samples from healthy children and children with kidney stones to obtain differentially expressed genes (DEGs). Genes related to mitochondrial oxidative stress were obtained from the Genecards website and intersected with DEGs to obtain candidate target genes. Additionally, we conducted protein-protein interaction (PPI) analysis using the STRING database to identify core genes involved in pediatric kidney stone disease (KSD) and predicted their transcription factors using the hTFtarget database. We assessed the impact of MyoD1 on the activity of the PINK1 promoter using dual-luciferase reporter assays and investigated the enrichment of MyoD1 on the PINK1 promoter through chromatin immunoprecipitation (ChIP) experiments. To validate our hypothesis, we selected HK-2 cells and established an in vitro kidney stone model induced by calcium oxalate monohydrate (COM). We evaluated the expression levels of various genes, cell viability, volume of adherent crystals in each group, as well as mitochondrial oxidative stress in cells by measuring mitochondrial membrane potential (Δψm), superoxide dismutase (SOD) activity, reactive oxygen species (ROS), and malondialdehyde (MDA) content. Mitochondrial autophagy was assessed using mtDNA fluorescence staining and Western blot analysis of PINK1-related proteins. Apoptosis-related proteins were evaluated using Western blot analysis, and cell apoptosis was measured using flow cytometry. Furthermore, we developed a rat model of KSD and assessed the expression levels of various genes, as well as the pathologic changes in rat renal tissues using H&E and von Kossa staining, transmission electron microscopy (TEM), and the expression of creatinine, blood urea nitrogen, neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1) to evaluate the mitochondrial oxidative stress in vivo (through measurement of Δψm, SOD activity, ROS, and MDA content). Mitochondrial autophagy was evaluated by Western blot analysis of PINK1-associated proteins. Apoptosis-related proteins were detected using Western blot analysis, and cellular apoptosis was examined using cell flow cytometry and TUNEL staining. Bioinformatics analysis revealed that the PINK1 gene is upregulated and vital in pediatric kidney stone patients. Our in vitro and in vivo experiments demonstrated that silencing PINK1 could inhibit kidney stone formation by suppressing mitochondrial oxidative stress both in vitro and in vivo. We identified MyoD1 as an upstream transcription factor of PINK1 that contributes to the occurrence of pediatric kidney stones through the activation of PINK1. Our in vivo and in vitro experiments collectively confirmed that silencing MyoD1 could inhibit mitochondrial oxidative stress, mitochondrial autophagy, and cellular apoptosis in a rat model of kidney stones by downregulating PINK1 expression, consequently suppressing the formation of kidney stones. In this study, we discovered that MyoD1 may promote kidney stone formation and development in pediatric patients by transcriptionally activating PINK1 to induce mitochondrial oxidative stress.

Comprehensive analysis of organic dye doped metal-coordinated single crystals: A study of structural, optical, thermal, dielectric, piezoelectric and mechanical characteristics

Organic dye can induce positive changes in optical, mechanical and electrical properties of semi-organic single crystals. Single crystals of pure and 0.01 mol% SSY dye doped ZTS are grown from a slow evaporation solution technique. The structural properties of pure and SSY-dyed ZTS crystals are characterized using SCXRD and PXRD, confirming the maintenance of crystallinity and incorporation of dye molecules within the host lattice of ZTS crystal. Both ZTS crystals belong to orthorhombic crystal system with space group Pca21. The refined lattice parameters and cell volume of present pure ZTS crystal are a = 11.1723 Å, b = 7.7989 Å, c = 15.5357 Å, α = β = γ = 90°, V = 1353.6762 Å3. The intensity of all Raman peaks in ZTS is enhanced by the incorporation of dye. Optical spectroscopic UV–visible and photoluminescence techniques highlight the comparative studies of light absorption, energy bandgap, optical constants and fluorescence emission. An increment of 0.05 eV in optical bandgap is observed in dyed ZTS. The dielectric properties with variation in frequency range (23 Hz–10 MHz) at different temperature range (30–100 °C) are evaluated through impedance spectroscopy, showing an increase in dielectric constant around 15 % and reduction in dielectric loss, indicating potential for improved performance in electronic applications. A significant enhancement is observed in the piezoelectric coefficient (d33) in dyed ZTS single crystals. The d33 value of ZTS is increased from 2.75 to 2.95 pC/N by the doping of organic dye. Vickers micro-hardness tester is used to know the mechanical strength through micro-indentation, which illustrated an increase in the hardness nature of dyed ZTS single crystals. These findings provide a foundation for the future development of ZTS-based materials for technological applications, offering a promising route for the advancement of functional materials in the domain of piezoelectric and optoelectronic technologies.

Baseline Dual-Energy Computed Tomography Urate Volume Predicts Fulfillment of Gout Remission After Two Years of Urate-Lowering Therapy.

This study aimed to identify variables that predict gout remission in people with erosive gout receiving urate-lowering therapy. We analyzed data from a two-year, double-masked randomized-controlled trial of people with erosive gout, randomized to a serum urate target of <0.20 mmol/L or <0.30 mmol/L using oral urate-lowering therapies. All participants had dual-energy computed tomography (DECT) scans of the feet and ankles at baseline. The proportion of participants achieving gout remission according to the 2016 preliminary gout remission criteria and simplified gout remission criteria (without the patient reported outcomes) was analyzed. Logistic regression models were used to evaluate predictors of gout remission in year 2. The preliminary gout remission criteria were fulfilled in 11 of 97 participants (11%) at year 1 and 21 of 92 participants (23%) at year 2. The simplified criteria were fulfilled in 26 of 97 participants (27%) in year 1 and 40 of 92 participants (44%) in year 2. In multivariable regression models, baseline DECT monosodium urate crystal volume was the only significant independent predictor of gout remission at year 2, using either criteria. Each 1-cm3 increase in the baseline DECT monosodium urate crystal volume decreased the odds of fulfilling the 2016 preliminary gout remission criteria (odds ratio [OR] 0.65, 95% confidence interval [CI] 0.46-0.93; P = 0.02) and the simplified gout remission criteria (OR 0.57, 95% CI 0.41-0.78; P < 0.001). In people with erosive gout on urate-lowering therapy, higher baseline DECT monosodium urate crystal volume is associated with lower odds of gout remission after two years of treatment, defined by either the preliminary gout remission criteria or simplified gout remission criteria.

Fast, One‐Step In Situ Synthesis of a Hierarchical Sn4+‐Doped TiNb2O7 Nanosphere as a High‐Performance Anode Material

AbstractTitanium niobium oxide (TNO) exhibits great potential as a lithium‐ion battery anode due to its high capacity, minimal volume change during cycling, and safe good operation characteristic enabled from its voltage profile. However, its intrinsically low electronic and ionic conductivity hinders its potential for practical applications. This work proposes a facile coprecipitation method to address these limitations by incorporating a nano‐macro structure and in situ Sn ion doping into bulk TNO. This approach ensures homogeneous integration of TNO precursors and the Sn dopant at a molecular level within the co‐precipitation nanoparticles. Additionally, the use of low toxicity solvents facilitate scalability of the synthesis process. Excellent rate capability, high reversible capacities, and good capacity retention are achieved simultaneously due to synergistic effects of the bulk doping, which expands the crystal volume and enhances Li+ diffusion, combined with abundant surface area of the nano‐macro structures. The specific capacity of Sn‐doped TNO nanospheres remains at 180 mAh/g at a high current density of 40 C (1 C=400 mA g−1), which is nearly four times higher than that of undoped samples. Furthermore, the cyclic voltammetry analysis at various scanning rates reveals an increased Li+ diffusion rate in Sn doped titanium niobium dioxide.

Relationship between serum urate and changes in dual-energy CT monosodium urate crystal volume over 1 year in people with gout: an individual participant data analysis

ObjectivesThe dynamics of monosodium urate (MSU) crystal changes across a range of serum urate concentrations in people with gout are unknown. This study aimed to systematically examine the relationship between...

Green solutions for desalinated water drip irrigation systems: Organic acids outperform inorganic acids in fouling control

Desalinated saline water (DSW) has been widely applied in many fields due to global water scarcity. However, fouling formation in desalinated saline water distribution systems (DSWDS) raises serious technical concerns. The conventional approaches (e.g., inorganic acids) for DSWDS fouling control is not only ineffective sometimes but also lead to serious environmental and health risks. Accordingly, this study introduces a greener method utilizing organic acids for antifouling in DSWDS. The performances and influences of three types of inorganic acids (hydrochloric acid (HCl), phosphoric acid (H3PO4) and hydrofluoric acid (HF)) and three types of organic acids (citric acid (C6H8O7), formic acid (CH2O2) and oxalic acid (H2C2O4)) on DSWDS fouling control were investigated and compared. The obtained results indicated that in general, organic acids exhibited higher antifouling capacities than inorganic acids. Among the selected six acids, CH2O2 was the most effective, followed by H2C2O4, H3PO4, C6H8O7, HCl, and HF. In comparison with the most commonly used inorganic HCl, the fouling dry weights in the samples treated with C6H8O7, CH2O2, and H2C2O4 reduced by an average of 8.9 %, 45.3 %, and 33.2 %, respectively. Despite the higher acidity of inorganic acid solutions compared to organic acids, the latter exhibited a stronger chelating capacity for cations (e.g., Ca2+, Mg2+) in DSW, showing a lower tendency to form precipitation in their treated groups. Moreover, organic acids could increase the crystal cell volume and change the chemical bond length of chemical precipitation, resulting in lattice distortions. Furthermore, organic acids can slow down the flocculation and settling of suspended particulate matter, thereby alleviating the formation of particulate fouling. Overall, these findings suggest that the application of organic acids is a more effective and environmental-friendly approach for fouling control compared to inorganic acids, which provides qualitative and quantitative insights into developing greener antifouling protocol for DSW delivery in actual field practices.

Comparative insight into crystal evolutions of monodisperse MNb2O6 (M = Ni, Cu, Zn) spheres during electrochemical cycling in Li/Al-ion batteries

Niobates have emerged as advanced anode materials for lithium-ion batteries, owing to their inherently higher voltage and the occurrence of multiple one-electron redox reactions. However, there is a lack of comprehensive comparative analysis regarding their performance in lithium-ion and aluminum-ion battery applications. In this study, a facile solvothermal process is developed to synthesize uniform submicrospheres of three niobates: NiNb2O6, CuNb2O6, and ZnNb2O6 with large specific surface area and narrow size distribution. Their superior textural properties consisting of interconnected nanograins offer numerous active sites, delivering enhanced capacity and rate performance for the constructed half and full cells. Our in-situ XRD analysis reveals that all three niobates exhibit ultralow crystal volume expansion (< 6 %). But they exhibit distinct ion storage mechanisms: CuNb2O6 undergoes a phase transition to LiNb3O8 and NbO2 upon cyclic insertion of Li+ ions; NiNb2O6 mainly involves a classic hybrid-controlled process, facilitating easy ion insertion/extraction into/from the crystal lattices, especially at low sweep rates; while ZnNb2O6 stores charges via a pseudocapacitive-controlled process. Density functional theory (DFT) calculation and ex-situ XRD analysis confirm that CuNb2O6 outperforms the others, displaying the best electrochemical performance and holding promise as a high-energy electrode material thanks to favorable phase conversion, enhanced transport channels, porous structure and spherical morphology.

Structural evolution of zirconium diboride under gamma irradiation and thermal annealing

Understanding the thermal properties and enhancing the performance of zirconium diboride (ZrB2) under extreme conditions is crucial, especially given its role as a burnable absorber in nuclear fuel pellets and its potential applications in accident-tolerant fuels. This study explores the structural alterations of ZrB2 crystals induced by gamma irradiation and subsequent thermal annealing. ZrB2 crystals were exposed to absorption doses of 300 kGy, 1000 kGy, 1500 kGy, and 3000 kGy using a 60Co gamma source, followed by thermal treatment at 1173 K under vacuum conditions. Also, Monte Carlo simulations were utilized to analyze the energy deposition and distribution of gamma quanta within the material during irradiation, highlighting Compton effects up to 0.23 MeV. X-ray diffraction analysis elucidated the impact of gamma radiation on ZrB2 crystal lattice parameters, space group, and volume expansion coefficient. Post-irradiation analysis revealed a maximum degree of amorphization and investigated mechanisms governing lattice parameter expansion. Thermal annealing at 1173 K significantly enhanced crystallinity, reducing amorphization to 0.2 % at an absorption dose of 3000 kGy and facilitating the restoration of the crystal's columnar structure. This comprehensive investigation provides insights into the intricate interplay between gamma irradiation, thermal processing, and resulting structural changes in ZrB2 nanocrystals, essential for applications in radiation-exposed environments.

Selective amplification effect on the diffraction efficiency of a phase grating generated by femtosecond laser pulses.

A phase grating that selectively amplifies diffraction orders that are multiples of a determined integer is designed. For the proposed grating, multiples of the fourth order are enhanced. These results are supported by experiments. The structure is inscribed in the volume of a lithium niobate crystal by employing the femtosecond laser pulse micro-machining technique. A model based on the Raman-Nath behavior of the grating predicts a diffraction efficiency enhancement for those selected orders. Moreover, it is observed that by changing the incidence angle allows transferring energy from multiples of fourth orders to multiples of three. These findings have potential applications in optical spectroscopy and optical communications as well as for photonic devices in which a controlled energy exchange between orders is necessary. The basic wave nature of the mentioned effect allows finding a counterpart in different wavelength ranges of the electromagnetic spectrum.

Viscous crack healing in soda–lime–magnesium–silicate–ZrO2 glass matrix composites

AbstractThe present study investigates the influence of the crystal volume content on viscous crack healing in glass ceramic glass sealants. To ensure constant microstructure during healing, soda–lime–magnesium silicate glass matrix composites with varied volume fractions of ZrO2 filler particles were used. Crack healing was studied on radial cracks induced by Vickers indentation, which were stepwise annealed to monitor the healing progress by confocal laser scanning microscopy. Confirming previous studies, healing of radial cracks in pure glass was found delayed by global flow phenomena like crack widening and crack edge and tip rounding to minimize the sample surface. With increasing ZrO2 filler content, these global flow phenomena were progressively inhibited whereas local flow phenomena like sharp crack tip healing could still occur. As a result, crack healing was even accelerated by filler particles up to a maximum filler content of 17 vol% whereas crack healing was fully suppressed only at 33 vol% filler content.

Enhancement of electrochemical stability by molecular cation vacancies of the electrode material CH3NH3NiCl3 for lithium-ion batteries

At present, efforts are being made to find new low-cost materials for photovoltaic, optoelectronic and energy storage applications. In this regard, compounds of the halide perovskite type have been increasingly studied over the past few years. The incorporation of small cations in these compounds and their possible use in rechargeable batteries can be achieved by the electrochemical reversibility technique, where perovskites with large cations are used to obtain a new isostructural compound with smaller cations and large interstitial space or free vacancies for ionic transport. The present work studied the electrochemical reversibility of lithium-ion into CH3NH3NiCl3 (MANiCl3) active material, after the formation of MA+ vacancies or interstitial spaces, taking both experimental and theoretical approaches. The material displayed an anodic behavior and an initial capacity of discharge of ca. 170 mAhg−1 at 0.2C (0.1 mA), a full capacity retention up to the first 25 cycles of charge–discharge, and even reached a retention of up to 80 % of initial capacity at the 80th cycle. First-principles density functional theory calculations show that the shape of the crystal lattice and volume changes of all the different phases involved in the electrochemical process are tiny, at about 3 Å3 per cell. In addition, there are no appreciable elastic contributions to the energy variation during the de-lithiation/lithiation process, indicating that memory effects are not an issue. The calculated formation energies of the lithiated structures and the open circuit voltages are −2.91 eV and 1.33 V for LinMA1-nNiCl3 and −1.41 eV and 2.91 V for Li2nMA1-nNiCl3, respectively. These findings suggest that incorporating one or, at most, to two lithium atoms is favorable for the overall stability and electrochemical performance.