Lithium Phosphate Research Articles

Self-Diffusion Effect Assisted TiO2/Li3PO4 Electron Selective Passivating Contact in Silicon Solar Cells Approaching 23% Efficiency.

Carrier selective contacts with passivation effects are considered to have a significant influence on the performance of crystalline silicon (c-Si) solar cells. It is essential for electron selective contact materials to meet the requirements of ultra-low contact resistance and excellent passivation effects. This work introduces a stack layer of Lithium Phosphate (Li3PO4) /Titanium Dioxide (TiO2) as a new electron selective passivating contact. It is found that the stack achieves an impressive contact resistivity (ρc) of 0.128mΩcm2 on n-type c-Si substrates with resistivity ranging from 1 to 3Ωcm (14.6mΩcm2 for the n-Si/a-Si:H/Li3PO4/TiO2/Al contact). Furthermore, it effectively reduces the surface recombination parameter (J0) to less than 4fA by incorporating a 6nm a-Si:H(i) layer. The characterization of the n-Si/Li3PO4/TiO2 interface reveals that phosphorus diffusion into silicon plays a crucial role in achieving the ultra-low contact resistivity, while the presence of PO4 3- groups helps in fixing hydrogen atoms to maintain the desired chemical passivation effect. Finally, a silicon heterojunction solar cell (SHJ) with a rear full-area configuration of a-Si:H/Li3PO4/TiO2/Al is successfully demonstrated achieving an impressive power conversion efficiency of 22.89%. The result proves the efficacy of employing hydrogen-rich low-work function metal oxide stacks as electron selective passivating contacts.

Electrochemical performance study of AlF₃-containing lithium phosphate glass electrolytes

This study aims to enhance the performance of Li₂O-P₂O₅-based lithium phosphate glass electrolytes for all-solid-state lithium batteries by incorporating aluminum fluoride (AlF₃). Initially, Li₂O-P₂O₅ glass was melted, followed by the addition of stoichiometric AlF₃, and remelted to achieve an optimized composition of 10AlF₃⋅50Li₂O⋅40P₂O₅. By adjusting the melting temperatures and the ratios of raw materials, we explored different synthesis procedures and obtained the lithium fluoro-phosphate glass electrolytes and systematically investigated their physicochemical properties and electrochemical performance. Its physicochemical properties include the glass composition, NMR spectra, and glass transition temperature. Symmetrical cell tests conducted at high current densities demonstrated that the incorporation of AlF₃ significantly enhanced the stability of the interface with lithium metal, maintaining excellent cycling performance. Furthermore, the doping with AlF₃ did not reduce the ionic conductivity of the original Li₂O-P₂O₅-based glass electrolyte, and the activation energy remained unchangeable.

Development of an ESP32 Microcontroller-based Colorimeter with an Android App for the Verification of Roasting Degree of Coffee Beans

A lo w-cost and portable colorimeter was developed using an ESP32 microcontroller and a TCS34725 color sensor to monitor the degree of coffee roast, crucial for maintaining flavor consistency and controlling product quality across different batches. The colorimeter detected color recognition resulting in RGB color intensity values, which could be displayed on the device’s TFT LCD touchscreen. Additionally, colorimetric data was transmitted in real-time via WiFi and stored in a MySQL database using an Android app created with the MIT App Inventor platform. The colorimeter was powered by a rechargeable lithium phosphate battery. The consistency of coffee roasting was ensured by self-identifying the standard RGB values of the roasted coffee beans at five degrees (light, light-medium, medium, medium-dark, and dark) with the app. The darker the color of the roasted coffee, the lower the RGB values were gained. The color detection was highly precise, with a relative standard deviation of less than 5%.

Electrochemical Performance of Deposited LiPON Film/Lithium Electrode in Lithium-Sulfur Batteries.

This paper presents a composed lithium phosphate (LiPON) solid electrolyte interface (SEI) film which was coated on a lithium electrode via an electrodeposit method in a lithium-sulfur battery, and the structure of the product was characterized through infrared spectrum (IR) analysis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), environment scanning electron microscope (ESEM), etc. Meanwhile, the electrochemical impedance spectrum and the interface stability of the lithium electrode with the LiPON film was analyzed, while the coulomb efficiency and the cycle life of the lithium electrode with the LiPON film in the lithium-sulfur battery were also studied. It was found that this kind of film can effectively inhibit the charge from transferring at the interface between the electrode and the solution, which can produce a more stable interface impedance on the electrode, thereby improving the interface contact with the electrolyte, and effectively improve the discharge performance, cycle life, and the coulomb efficiency of the lithium-sulfur battery. This is of great significance for the further development of solid electrolyte facial mask technology for lithium-sulfur batteries.

A novel approach for the direct production of lithium phosphate from brine and the synthesis of lithium iron phosphate

The secure supply of lithium is vital for the sustainable development of energy-related industries such as electric vehicles, and grid-level energy storage systems. Salt lake brines as important lithium resources, have a profound impact on the supply of lithium. Among them, carbonate-type brine has gained attention due to the advantage of not requiring lithium‑magnesium separation. However, carbonate-type brines have not been efficiently utilized due to their complex composition and high alkalinity. This paper introduces a method for directly obtained Li3PO4 from carbonate-type brine by seed-induced precipitation, avoiding the time-consuming evaporation and concentration processes in existing methods. The effect of each reaction condition on lithium recovery was investigated in detail and the optimal reaction conditions were determined. The recycling experiment of seeds confirms that the seed was reusable, reducing costs and environmental impact. Additionally, the LiFePO4/C with good electrochemical performance was synthesized using the Li3PO4 obtained from brine. This novel approach achieves a closed-loop production from mineral resources to battery materials, demonstrating strong competitiveness and industrial prospects.

Recovery of Lithium from Industrial Li-Containing Wastewater Using Fluidized-Bed Homogeneous Granulation Technology

In this study, a novel fluidized-bed homogeneous granulation (FBHo-G) process was developed to recover lithium (Li) from industrial Li-impacted wastewater. Five important operational variables (i.e., temperatures, pH, [P]0/[Li]0 molar ratios, surface loadings, and up-flow velocities (Umf)) were selected to optimize the Li recovery (TR%) and granulation ratio (GR%) efficiencies of the process. The optimal operational conditions were determined as the following: a temperature of 75 °C, pH of 11.5, [P]0/[Li]0 of 0.5, surface loading of 2.5 kg/m2·h, and Umf of 35.7 m/h). The TR% and GR% at optimal condition could be as much as 90%. The material characterization of the recovery pellet products showed that they were highly crystallized Li3PO4 (purity ~88.2%). The pellets had a round shape and smooth surface with an average size of 0.65 mm, so could easily be stored and transported. The high purity enables them to be further directly reused as raw materials for a wide range of industrial applications (e.g., in the synthesis of cathode materials). Our calculation shows that the FBHo-G process could recover up to 0.1845 kg of lithium per cubic meter of Li-containing wastewater, at a recovery rate of ~90%. A brief technoeconomic analysis shows that FBHG process had economic viability, with an estimate production cost of USD 26/kg Li removed, while the potential gained profit for selling lithium phosphate pellets could be up to USD 48 per the same volume of wastewater and the net profit up to USD 22/m3 Li treated. In all, fluidized-bed homogeneous granulation, a seedless one-step recovery process, opens a promising pathway toward a green and sustainable recycling industry for the recovery and application of the resource-limited lithium element from nonconventional water sources.

Thiocarbamoyl sulfamic acid‐derived mesoporous silica: a comprehensive study on selective adsorption of cobalt and lithium from spent lithium‐ion batteries

AbstractBACKGROUNDThe recycling of spent lithium‐ion batteries (LIBs) is crucial for resource conservation and environmental sustainability, particularly due to the valuable metals they contain, such as cobalt and lithium. This study focuses on developing an ion‐exchange method for cobalt recovery from waste LIB solutions, using a mesoporous silica derivative of carbamoyl sulfamic acid (PST‐SA) as the adsorbent.RESULTSThe batch method for adsorption experiments identified the most effective conditions: a pH of 8, 0.08 g PST‐SA, and a shaking time of 60 min, at room temperature. These experiments demonstrated a remarkable cobalt uptake capacity of 270.70 mg g−1, highlighting PST‐SA's exceptional adsorption capabilities. Additionally, thermodynamic studies revealed the adsorption process to be both endothermic and spontaneous, enhancing our understanding of its chemically reactive mechanisms.CONCLUSIONSThe practical application of PST‐SA, particularly when processing spent LIBs, showcases its real‐world utility. The efficient separation of cobaltous oxalate and lithium phosphate into pure forms emphasizes PST‐SA's potential in recycling and resource recovery. Given its cost‐effectiveness and strong adsorption capacity, PST‐SA stands out as an excellent solution for the removal of Co(II) from discarded LIBs, promoting sustainable material recovery practices. © 2024 Society of Chemical Industry (SCI).

Hydrothermal synthesis of LiMn0.79Fe0.2Mg0.01PO4/C composite cathode materials using different Li3PO4 precursors

Doping and particle size controlling are two important approaches to improve the electrochemical performance of LiMnxFe1−xPO4 cathode materials. By employing a straightforward hydrothermal method and utilizing cost-effective lithium phosphate (Li3PO4) as the precursor, we successfully synthesized high Mn-content LiMn0.79Fe0.2Mg0.01PO4/C composites. The results reveal that the minute amount of Mg substantially enhances the electrochemical performance. In the subsequent mechanism study using Li3PO4 precursors with different particle size, we found that the nucleation process, dependent on specific surface area and diffusion rate, is likely to play a critical role for the size and morphology of formed LiMn0.79Fe0.2Mg0.01PO4. LiMn0.79Fe0.2Mg0.01PO4/C (LMFP-1), synthesized from initially smaller-sized and less agglomerated Li3PO4 (LPO-1), exhibited the most diminutive average particle size coupled with the highest specific surface area, which further facilitated electrolyte interfacial interaction and promoted Li+ diffusion kinetics. At 1C, LMFP-1 displayed a specific capacity of 110.7 mAh g−1, with 97.07% capacity retention after 200 cycles. This study provides pivotal insights for the synthesis of high-performance LiMnxFe1−xPO4 materials.

Interdiffusion suppression at the cathode‐electrolyte interface of all‐solid‐state‐batteries by Li3PO4 conformal coating

AbstractAll‐solid‐state lithium batteries (ASSLBs) are promising energy‐storage devices with high energy density and safety. However, the discharge capacity of ASSLBs that use sulfide solid electrolytes (SEs) and Ni‐rich cathode active materials (CAMs) deteriorates significantly during electrochemical cycling. Interfacial coatings between CAM and sulfide SEs are known to effectively alleviate capacity deterioration. Among the various coating materials, lithium phosphate (LPO) was selected and synthesized via atomic layer deposition (ALD). The crystal phase of the LPO thin film irreversibly changed, and the Li‐ion conductivity deteriorated after heat treatment. Additionally, particle ALD (P‐ALD) of LPO was successfully performed to completely passivate the CAM particles. Torque cells with the LPO‐coated CAMs showed excellent capacity retention, whereas the cells without the LPO coating showed a significantly deteriorated discharge capacity with increased internal resistances. The passivation effect of the LPO coating was confirmed by the cross‐sectional images from a FIB and scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM–EDS) dual system. We believe that the study will help us investigate the effects of side reactions between sulfide SEs and CAMs on the performance and stability of P‐ALD.

Recovery of pure lithium phosphate from sulfuric acid leaching solutions of spent LiFePO4 batteries by solvent extraction and chemical precipitation

With the increasing use of electric vehicles, the demand for lithium iron phosphate batteries (LiFePO4) has risen sharply. Therefore, the recycling of metals from these batteries at the end of their life is necessary. In this study, a hydrometallurgical process for the recovery of lithium phosphate from spent LiFePO4 batteries was developed. The effects of the parameters on the recovery process, consisting of leaching, solvent extraction, and precipitation were investigated. The addition of H2O2 to the H2SO4 solution was ineffective for the selective leaching of Li(I) over iron. The results showed that Li(I) and iron were completely dissolved by 1.5 mol/L H2SO4, 100 g/L pulp density at 25 ?C for 60 min at 300 rpm. After oxidation of Fe(II) in the leaching solution by addition of H2O2, Fe(III) was completely separated from the solution by five steps of cross-flow extraction with 1.0 mol/L D2EHPA at room temperature. The loaded Fe(III) was successfully separated by four steps of cross-current stripping with 50% (v/v) aqua regia solution. Finally, most Li(I) was recovered by precipitation of lithium phosphate from the iron-free raffinate by maintaining the pH of the solution at 11 and the temperature at 95 ?C for 30 min. The optimum conditions for the complete dissolution of LiFePO4 batteries by sulfuric acid solution and for the separation of iron and lithium ions from the leaching solutions were determined. A hydrometallurgical process was proposed for the recovery of pure lithium phosphate from spent LiFePO4 batteries.

Advancing solid-state lithium phosphate electrolyte: Synthesis and characterization of Li2NaPO4–ZrO2 nanocomposites for solid-state batteries

Lithium phosphates are one of the most promising groups of inorganic solid electrolytes under investigation owing to their excellent Li-ion conductivity. A series of compositions with different weight percentages of (1-x) Li2NaPO4-(x) ZrO2 samples have been prepared by the solid-state technique and characterized by FT-IR, XRD, SEM-EDS, TEM, and Impedance Spectroscopy. Among the various compositions, 20 wt % ZrO2 exhibits the highest ionic conductivity, i.e., σ = 4.5 × 10−3 Scm−1, and the lowest activation energy 0.0759 eV at 298 K. XRD analysis reveals that the addition of ZrO2 nano-filler up to the optimum value of 20 wt % suggests the formation of the amorphous phase. SEM micrographs reveal that the introduction of ZrO2 nanofiller reduces the crystallinity of the Li2NaPO4 and enhances the ionic conductivity compared with pure Li2NaPO4. Our study marks substantial advancement in the synthesis of innovative nanocomposite solid electrolytes for batteries with superior energy storage capacities.

A sustainable method for lithium recovery from waste liquids: Thermodynamic analysis and application

In this study, lithium was efficiently enriched and recovered from low concentration waste liquids by sodium phosphate precipitation and wet conversion. Firstly, the efficient extraction of lithium at low concentration was realized based on the lower solubility of lithium phosphate. The factors involved in the lithium phosphate precipitation process by sodium phosphate were systematically investigated, and it was discovered that the high temperature process promoted the formation of lithium phosphate, with the lithium precipitation rate reached 94.32% under optimal conditions. The feasibility of the conversion of lithium phosphate into lithium chloride solution and iron phosphate by ferric chloride solution was analyzed by thermodynamic study. The experimental results also further confirmed that the lithium conversion rate was as high as 96.06% when the reaction temperature was 25 °C and the pH of the system was 2. The conversion process achieved the enrichment of lithium from low to high concentrations, avoiding the high energy consumption caused by conventional evaporation and concentration. More importantly, the alkaline leaching of the converted residue realized the separation of phosphorus and iron sources, and then the re-synthesis of ferric chloride solution and sodium phosphate reagent was accomplished by acid leaching and crystallization, respectively, allowing for reagent recycling in the lithium extraction process. The proposed process is expected to provide a green and sustainable route for the recovery of low concentration lithium from waste liquids.

Atomic Layer Deposition of Lithium Borate and Borophosphate Thin Films for Lithium-Ion Battery Applications

Lithium-ion batteries (LiBs) are widely used in portable electronic devices and electric vehicles because of their high energy density and long cycle life. However, their performance is limited by unwanted side reactions that occur at the electrolyte-electrode interface during charge/discharge cycles.Previous studies have indicated that the application of a conformal and ultra-thin protective coating on the electrode surface through atomic layer deposition (ALD) is a promising strategy to prevent these undesired side reactions [1]. Due to their high stability, metal phosphates are deemed a promising class of materials for protective coatings, and several studies have focused on ALD of metal phosphates [2], with lithium phosphate as a particularly relevant material. However, the low ionic conductivity, as evidenced by the reported value of 1.4 x 10-10 S cm-1 with an activation energy of 0.92 eV for crystalline Li3PO4 films deposited by ALD [3] may hinder the flow of lithium ions through the coating. It has been shown, albeit using other deposition techniques, that the inclusion of borate species can enhance the ionic conductivity of phosphate materials, including lithium phosphate [4]. However, lithium borates exhibit a more narrow electrochemical stability window. Here, we investigate the combination of lithium phosphate and lithium borate into a new, intermixed ALD coating, i.e. lithium borophosphate, aiming to increase the ionic conductivity of the protective coating while preserving as much as possible its electrochemical stability.To date, only one ALD process for lithium borate has been reported by Kazyak et al. [5], which resulted in films with significant carbon incorporation. In this work, we have developed an ALD process for depositing lithium borate with minimal contaminants (< 5 at.% as determined by XPS) using LiHMDS, H2O and TMB as precursors. Through-plane impedance spectroscopy measurements were used to determine the ionic conductivity. For a lithium borate ALD film with a thickness of 81 nm deposited at 250°C, an ionic conductivity of 1.60 ± 0.03 x 10-7 S cm-1 was obtained at 30 °C, with an activation energy of 0.58 ± 0.01 eV.By combining this lithium borate ALD process with the well-known lithium phosphate ALD process [6], the composition of the film could be precisely controlled, resulting in tailored electrochemical properties. Cyclic voltammetry was employed to evaluate the electrochemical stability of the lithium borophosphate mixtures. The coatings were deposited on top of an ion-blocking material and cycled to high voltages. Initial results indicate that the stability of the coating material decreases as the amount of lithium borate to lithium phosphate cycles increases.These promising preliminary results demonstrate that ALD is a valuable tool in developing high-performance battery technologies, enabling the deposition of new protective coatings with controllable electrochemical properties. Finding the optimal lithium borophosphate coating will require a trade-off between ionic conductivity and electrochemical stability and will ultimately depend on the intended application. References Jung, Y. S., J. Electrochem. Soc. 157, A75 (2009).Henderick, L., Appl. Phys. Rev. 9, 011310 (2022).Put, B., J. Electrochem. Soc. 166, A1239 (2019).Magistris, A., J. Power Sources 14, 87 (1985).Kazyak, E., J. Mater. Chem. A 6, 19425 (2018).Hämäläinen, J., J. Electrochem. Soc. 159, A259 (2012). Figure 1

In vitro biodegradation, blood, and cytocompatibility studies of a bioactive lithium silicate glass-ceramic

This study investigates a novel non-stoichiometric lithia-silica glass-ceramic (Bioactive LD) designed for bone tissue engineering applications. Incorporating SiO2–Li2O–CaO–P2O5–K2O–SrO–ZnO, the glass-ceramic underwent optimized thermal treatments resulting in a composition predominantly of lithium disilicate (Li2Si2O5 - 87 %) with a minor lithium phosphate phase (Li3PO4 - 13 %). Structural analysis using X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed a refined microstructure with Li2Si2O5 crystals in rod form with a high aspect ratio of around 4:1. Expanding on previous work, this study investigates the in vitro osteoblastic response of Bioactive LD compared to a commercial glass-ceramic (E-Max CAD®). The evaluation, employing live/dead assays, resazurin assays, and alkaline phosphatase activity measurements at different time points, demonstrated comparable cell viability and proliferation on both glass-ceramics. The chemical stability of the samples was tested, and the Bioactive LD showed a higher amount of leached ions in the solution, without significant mass loss, consistent with the standardized values for a class 4 material (ISO 6872), with no significant change in its microstructure. The chemical solubility tests were investigated employing SEM and energy dispersive X-ray analysis (EDS), giving insights into the role of leached ions in the microstructure and bioactivity of the materials. Notably, Bioactive LD exhibits higher alkaline phosphatase activity, indicating enhanced stimulation of osteoblastic cells. Additionally, the Bioactive LD promotes mineralization matrix production, as evidenced by alizarin red S staining. The study also employs SEM-EDS to evaluate the formation of apatite mineralized matrix. Bioactive LD exhibits a homogeneous mineralized matrix with increased Calcium and Sulfur signals, suggesting early hydroxyapatite formation after Alizarin Red S assay. In contrast, Commercial LD shows limited reactivity and bioactivity, with no substantial calcium deposition. An indirect cytotoxicity test indicates minimal cytotoxicity for Bioactive LD, while Commercial LD exhibits slight cytotoxicity, consistent with findings from the literature. The results highlight Bioactive LD's potential for bone regeneration, emphasizing its enhanced bioactivity and the formation of a complex mineralized matrix that could contribute to improved bone integration properties.

Finishing technique effect on strength of zirconia-reinforced lithium silicate ceramic.

The aim of this study was to evaluate the effect of two finishing techniques, glazing or polishing, in comparison with the as-cut condition, on the biaxial-flexural-strength (BFS) of a zirconia-reinforced lithium silicate ceramic (ZLS). Cylinders were milled from CAD/CAM blocks and sliced to obtain disc-shaped specimens (ISO6872:2015). Polished and glazed specimens were processed following the manufacturer's instructions. Thirty-three specimens were obtained for each condition and microstructural and BFS/fractographic characterizations were performed. BFS and roughness data were analyzed using Weibull statistics and ANOVA one-way with Tukey post-hoc test, respectively. While a rougher surface was observed for as-cut specimens, smoother surfaces were observed for polished and glazed ZLS at microscopical evaluation and confirmed through surface-roughness evaluation. X-ray spectra depicted aglass phase for all groups and characteristic metasilicate, lithium disilicate, and lithium phosphate peaks for the as-cut and polished specimens. Glazed specimens showed higher characteristic strength than polished and as-cut specimens, which did not differ significantly. While higher Weibull-modulus was observed for the polished than for the as-cut specimens, no statistically significant differences were noted between glazed and polished, and between glazed and as-cut specimens. ZLS presents higher strength when glazed, and polishing increases the structural reliability of the material relative to the as-cut condition. Both finishing techniques reduced surface roughness similarly.

Sequential separation and recovery of phosphorus and lithium from lithium phosphate slag by selective extraction-precipitation

The efficient utilization of lithium and phosphate resources from lithium phosphate slag, a byproduct originated from lithium extraction, holds great significance for environmental protection and industrial advancement. Existing methods primarily focus on Li extraction from this slag, while phosphate resources are often overlooked. In this work, we proposed an alternative approach based on impurity extraction, followed by sequential precipitation of FePO4 and Li2CO3, to concurrently recover lithium and phosphate from lithium phosphate slag. The results demonstrated an aluminum separation efficiency of 85 %, effectively reducing the aluminum concentration in the raffinate to below 25.0 mg/L. The extraction reaction, facilitated by saponification, involved cation exchange between Al3+ and Na+. The synthesis process of FePO4·2H2O was predominantly controlled by the chemical reaction with an activation energy of 102.8 kJ/mol. The obtained FePO4·2H2O and Li2CO3 products met the standards for battery-grade materials. Notably, the process achieved a remarkable phosphorus recovery rate of 98.7 % while maintaining a low lithium loss rate of below 2.0 %. This work presents an efficient and environmentally friendly method for achieving comprehensive recovery of lithium and phosphate resources from lithium phosphate slag.

New Approaches to Synthesizing Nanostructured Electrode Materials Based on Double Lithium and Cobalt Phosphates in Salt Melts

New Approaches to Synthesizing Nanostructured Electrode Materials Based on Double Lithium and Cobalt Phosphates in Salt Melts

Suppress moisture sensitivity of Ni-rich cathode materials by bioinspired self-assembly hydrophobic layer

Ni-rich layered oxides have shown great potential as lithium-ion batteries in the field of powered vehicles. However, the chemical instability at the cathode–air interface leads to high sensitivity in humid air and easily produces residual lithium, posing challenges for interfacial stability. In this work, we used alkyl phosphoric (AP) material as a bioinspired coating on the surface of LiNi0.83Mn0.11Co0.06O2 (N83) for molecular self-assembly to form a strongly robust cathode–air interface with improved chemical environmental stability. Results showed that the bioinspired self-assembled hydrophobic coating (BSHC) inhibits the formation of residual lithium due to Li+/H+ ion exchange on the high nickel surface and improves the stability of the cathode–air interface. Moreover, the lithium phosphate generated by surface conversion remarkably enhances the migration rate of Li+, alleviates irreversible gas release, and effectively inhibits electrolyte erosion. Given the synergistic effect, the Ni-rich material coated with 16 carbon chains of alkyl phosphoric (N83@16C) provide higher capacity (151.3 mAh/g) and capacity retention (91.38%) after 300 cycles, exhibiting excellent chemical and cycling stability after exposure. This work helps improve the environmental chemical stability of Ni-rich materials and provides guidance for the development of other cathode materials with sensitive cathode–air interfaces.

Synthesis of LiPON Solid Electrolyte Films by Thermal Evaporation of Lithium Orthophosphate

Lithium phosphorus-oxynitride (LiPON) films were deposited by the method of anodic evaporation of Li3PO4 in the nitrogen plasma of a low-pressure arc. A method for adjusting the degree of decomposition of vapors is proposed based on a change in the frequency of interaction of electrons with vapors at a constant heating power of the anode-crucible. The conditions ensuring the formation of films with a homogeneous microstructure and ionic conductivity (1–2) × 10−6 S/cm at a deposition rate of 8 nm/min have been determined. It is shown that the degree of vapor dissociation critically affects the morphology of the films and the magnitude of their ionic conductivity. The results of cyclic tests of LiPON films deposited by anodic evaporation in a low-pressure arc are presented.

Microstructure and mechanical properties of an experimental lithium disilicate dental glass-ceramic

After testing over 50 experimental lithium disilicate (LS2)-based glass-ceramic (GC) compositions and evaluating their glass-forming ability and the effect of various heat treatments on their crystallized fraction, crystal size, and morphology, a particularly promising formulation was selected for the optimization of the mechanical properties of materials. The specimens were divided into groups submitted to a nucleation heat treatment at different times and temperatures, i.e., T1 (500 °C/90′), T2 (500 °C/180′), T3 (500 °C/360′) and T4 (480 °C/360′), followed by a crystal growth treatment to induce the lithium metasilicate (700 °C) and LS2 (840 °C) phases. However, a third (minor) phase, lithium phosphate, also precipitated. IPS e.max CAD was used as the control group (C, 500 °C/360′). The elastic modulus (E) was measured by the impulse excitation technique (ASTM E 1876-15), while the Vickers hardness (HV) and biaxial flexural strength (BFS) were determined by indentation and the piston-on-three balls test (ISO 6872), respectively. The E and HV results were analyzed by ANOVA one-way with Games–Howell post-hoc test, whereas the BFS data were investigated by Kruskal-Wallis with Dunn's post-hoc test (α = 0.05). The E of all GCs were within the expected range for commercial LS2 glass-ceramics. The T2 and T4 GCs exhibited the best properties when compared to the C group, and despite their relatively small crystallized fraction (∼57 %), they showed a hardness of 5.8 ± 0.2 GPa, a value that is adequate and statistically equal to that of the control group. The same groups reached BFS values of 359 ± 89 MPa and 493 ± 147 MPa, respectively, which are also statistically equal to that of the C group (338 ± 61 MPa). The mechanical properties of the material studied was successfully optimized through variations in the nucleation temperature and time, reaching values comparable to (but not better than) commercial dental glass-ceramics.