Low-temperature Route Research Articles

A Low Temperature Calciothermic Reduction Approach for the Synthesis of LaB6 Powders

In this work, we report the synthesis of a polycrystalline LaB6 powders with a uniform morphology by a low-temperature metallothermic reduction route using calcium as a reductant. The processing methodology and heat treatment parameters are optimized based on thermodynamic estimates in order to favour the reaction kinetics and for complete formation of LaB6 powders with highest purity. The synthesised powder was subjected to comprehensive characterization studies. X-Ray Diffraction (XRD) revealed the complete formation of LaB6 compound without any traces of reactants. Scanning Electron Microscopy (FE-SEM) along with chemical mapping shows the morphology and elemental distribution of LaB6 powder. X-Ray Photoelectron Spectroscopy (XPS) results show the futuristic peaks with photon energies that are assigned to the core levels of the La and B without significant impurities whereas the Fourier transform infrared (FTIR) spectrum indicates an apparent presence of La-B bonds at 1045.4 cm−1, 585.5 cm−1, and at 463.1 cm−1.

In Situ Neutron Diffraction Showing Lithium-Yttrium Chloride Local Structure By Synthesis Method

Lithium halide-based solid electrolytes have high Li+ conductivity and are mostly synthesized through mechanochemical methods.[1] However, Li3InCl6 can be readily synthesized through low-temperature aqueous solution routes by mere dehydration, presumably due to stable InCl6 3- complexation. [2-4] Replacing In for Y results in partial hydrolysis to form YOCl during dehydration because H2O coordinates more strongly to Y3+ cations. We provide insight into the reaction mechanisms involved in synthesizing halide solid electrolytes, highlighting the importance of synthetic and processing conditions to optimize their performance in all-solid-state batteries. We will describe the synthesis process of Li3YCl6 using three different methods and the evolution thereof using in situ neutron diffraction. Our results show that aqueous-based synthesis requires the formation of an ammonium halide complex intermediate. We found that the synthesis method affects changes in local structure within the lattice, which then affect ionic transport and Li+ diffusivity, as determined through diffusion NMR measurements. We ascribe these changes to the correlative transport of Li+. Synthesis affects particle morphology at the macroscale and relates to cycle life when used in a full cell.This project was supported by the Vehicle Technologies Office (VTO) under the Office of Energy Efficiency and Renewable Energy (EERE) as part of the Battery Materials Research (BMR) program. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.[1] Park, K.-H.; Kaup, K.; Assoud, A.; Zhang, Q.; Wu, X.; Nazar, L. F. High-Voltage Superionic Halide Solid Electrolytes for All-Solid-State Li-Ion Batteries. ACS Energy Lett. 2020, 5, 2, 533–539.[2] Li, X.; Liang, J.; Luo, J.; Norouzi Banis, M.; Wang, C.; Li, W.; Deng, S.; Yu, C.; Zhao, F.; Hu, Y.; Sham, T.-K.; Zhang, L.; Zhao, S.; Lu, S.; Huang, H.; Li, R.; Adair, K. R.; Sun, X. Air-Stable Li3InCl6 Electrolyte with High Voltage Compatibility for All-Solid-State Batteries. Energy Environ. Sci. 2019, 12, 2665-2671.[3] Li, W.; Liang, J.; Li, M.; Adair, K. R.; Li, X.; Hu, Y.; Xiao, Q.; Feng, R.; Li, R.; Zhang, L.; Lu, S.; Huang, H.; Zhao, S.; Sham, T.-K.; Sun, X. Unraveling the Origin of Moisture Stability of Halide Solid- State Electrolytes by In Situ and Operando Synchrotron X-Ray Analytical Techniques. Chem. Mater. 2020,32, 16, 7019–7027.[4] Sacci, R.L.; Bennett, T.H.; Drews, A.R.; Anandan, V.; Kirkham, M.J.; Daemen, L.L.; Nanda, K. Phase evolution during lithium indium halide superionic conductor dehydration. J. Mater. Chem. A, 2021,9, 990-996.

Tuning Optical and Electrical Properties of Vanadium Oxide with Topochemical Reduction and Substitutional Tin.

Vanadium oxides are widely tunable materials, with many thermodynamically stable phases suitable for applications spanning catalysis to neuromorphic computing. The stability of vanadium in a range of oxidation states enables mixed-valence polymorphs of kinetically accessible metastable materials. Low-temperature synthetic routes to, and the properties of, these metastable materials are poorly understood and may unlock new optoelectronic and magnetic functionalities for expanded applications. In this work, we demonstrate topochemical reduction of α-V2O5 to produce metastable vanadium oxide phases with tunable oxygen vacancies (>6%) and simultaneous substitutional tin incorporation (>3.5%). The chemistry is carried out at low temperature (65 °C) with solution-phase SnCl2, where Sn2+ is oxidized to Sn4+ as V5+ sites are reduced to V4+ during oxygen vacancy formation. Despite high oxygen vacancy and tin concentrations, the transformations are topochemical in that the symmetry of the parent crystal remains intact, although the unit cell expands. Band structure calculations show that these vacancies contribute electrons to the lattice, whereas substitutional tin contributes holes, yielding a compensation doping effect and control over the electronic properties. The SnCl2 redox chemistry is effective on both solution-processed V2O5 nanoparticle inks and mesoporous films cast from untreated inks, enabling versatile routes toward functional films with tunable optical and electronic properties. The electrical conductance rises concomitantly with the SnCl2 concentration and treatment time, indicating a net increase in density of free electrons in the host lattice. This work provides a valuable demonstration of kinetic tailoring of electronic properties of vanadium-oxygen systems through top-down chemical manipulation from known thermodynamic phases.

Low-Temperature Synthesis of GeTe Nanoparticles.

Nanoparticles can offer an alternative approach to fabricate phase-change materials. The chemical synthesis of GeTe nanoparticles using organometallic precursors exploits high-boiling solvents and relatively high temperatures (close or even above crystallization temperatures), as reported in the available literature. The aim of this work is the preparation of GeTe nanoparticles by a low-temperature synthetic method exploiting new organometallic precursors and common organic solvents. Indeed, different preparation methods and characterization of GeTe nanoparticles is discussed. The characterization of the prepared nanomaterial was performed on the basis of X-ray diffraction, transmission electron microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, laser ablation time-of-flight mass spectrometry, Raman scattering spectroscopy, and dynamic light scattering. The results show that the low-temperature synthetic route leads to amorphous GeTe nanoparticles. Exploited organometallic precursor is stabilised by neutral ligand which can be isolated after the reaction and repeatedly used for further reactions. Furthermore, GeTe nanoparticle size can be tuned by the conditions of the synthesis.

Cold sintering of α- and γ-modifications of aluminum oxohydroxides: A low-temperature route to porous corundum ceramics

Objectives. To obtain porous corundum ceramics using an innovative cold sintering process starting from different phase modifications of aluminum oxohydroxide — boehmite γ-AlOOH and diaspore α-AlOOH; to study the phase and structural properties of the resulting materials; and to assess their permeability to water.Results. Cold sintering enables the formation of single-phase corundum ceramics with an open porosity of 47.9% directly from the initial boehmite powder with the addition of 5 wt % corundum in the presence of 20 wt % water at a temperature of 450°C, mechanical pressure of 220 MPa, and isothermal exposure for 30 min. Under the same conditions of cold sintering, a mixture of diaspore and boehmite was transformed into α-AlOOH ceramics. This then turned into corundum with an open porosity of 39% when calcined in air at 600°C for 1 h. The resulting materials had permeability for pure water above 5000 L/(m2∙h∙bar).Conclusions. Cold sintering is a promising approach to producing porous corundum ceramics which can be used in filtration systems. Compared to traditional ceramic technology, the new approach reduces energy, time, and labor costs in the material manufacturing. It also eliminates the need to use auxiliary substances (binders, pore-forming agents, etc.).

A synthetic method for lanthanum hydroxychloride suitable for industrialization and its thermal decomposition properties.

A reactive crystallization method for the synthesis of lanthanum hydroxychloride (La(OH)2Cl) was developed to provide a new low-carbon route for the purification of rare earth elements in hydrometallurgy. The synthetic method reported herein represents a unique low-temperature route, short preparation time and inexpensive materials compared with previous methods, thus making it promising for industrial applications. The key factors controlling the product's phase were determined using single factor tests involving temperature, concentration of NH4Cl in the base solution and the molar ratio of NH4OH/La3+ added per minute into the base solution. Otherwise, the outcome is lanthanum hydroxide (La(OH)3). Subsequently, the synthesized products were characterized by employing X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). Finally, the thermal decomposition behavior of La(OH)2Cl was assessed using thermogravimetry (TG) and differential scanning calorimetry (DSC). Lanthanum oxychloride (LaClO) was obtained at about 360 °C. The thermal transformation from LaClO to La2O3 started at 400 °C and was a slow oxidation process. Pure La2O3 could be obtained when the temperature increased to 1500 °C.

Enhanced properties of hard metal WC-Ni processed from nanostructured powders

In this study, we investigated the effects of nanostructured composite powders (WC-Ni), nickel binder content, and sintering techniques on the morphology and mechanical properties of tungsten carbide. An alternative low-temperature gas-solid reaction route with a short reaction time was employed to produce nanostructured composite powders with 5 and 15 wt% Ni. The powders were consolidated using spark plasma sintering (SPS) and conventional vacuum furnace sintering at temperatures of 1350 °C and 1450 °C. The composite powders were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and particle size measurements. The expansion/contraction of the compacted nanocomposite powders was studied through dilatometric analysis. The composite powders exhibited a uniform distribution of Ni, in both compositions. For the WC-5 wt% Ni nanocomposite powders, the average crystallite sizes for WC and Ni were 41.6 nm and 46.2 nm, respectively. While, for the WC-15 wt% Ni nanocomposite, the crystallite sizes for WC and Ni were 45.6 and 38.4 nm. The sintered composites were evaluated through XRD, SEM, measurements of density and Vickers hardness. The enhanced sinterability of the nanostructured powders enabled their consolidation into (WC-Ni) hard metal with densities approaching the theoretical relative density of 96.07 %, even with low binder content (5 wt% Ni). This is attributed to the uniform distribution of Ni and an extensive Ni-WC interface present prior to sintering. The SPS process at 1350 °C produced sintered bodies (WC-5 wt% Ni and WC-15 wt% Ni) with higher Vickers hardness (2322 HV and 1512 HV, respectively) and superior microstructural quality compared to samples produced by conventional vacuum furnace techniques. These results demonstrated that the mechanical properties of the system WC-Ni processed by SPS are superior to those obtained by vacuum furnace. Therefore, WC-Ni hard metals processed by this approach is a promising alternative to conventional hard metals (WC-Co) for a wide range of applications.

Structure and optical properties of ZnxCd1-xS and Cu:ZnxCd1-xS templated on DNA molecules

One-dimensional ZnxCd1−xS and Cu: Zn x Cd1−x S nanostructures were prepared using DNA as a template to promote growth along the molecular axis. The formation of homogeneously alloyed nanocrystals with cubic zinc blende-type structures was verified using x-ray diffraction and Raman spectroscopy. X-ray photoemission spectra revealed the presence of Cu(I) in the doped Cu: Zn x Cd1−x S nanocrystals. The effectiveness of the DNA template to direct the semiconductor growth in one dimension was demonstrated by AFM and TEM. The nanostructures displayed a granular morphology comprising nanoparticles with an average diameter of 14 nm composed of assemblies of smaller crystallites of 2.0 nm in size. Rope-like assemblies with an average diameter of 48 nm and extending in length to several hundred micrometres were obtained by evaporation-induced self-assembly. UV-Vis absorption and emission spectra indicated that the optical bandgaps (2.89–4.00eV) and photoluminescence peaks (608–819 nm) of the DNA-templated nanocrystals could be precisely controlled by modifying the molar ratios of their Zn/Cd precursors. Doping with Cu(I) gave an increase in photoluminescence intensity and a composition-independent red-shift of 0.23 eV. The preparation of DNA-templated Zn x Cd1−x S and Cu: Zn x Cd1−x S provides a simple, low-temperature route to aqueous dispersions of inorganic materials with controlled optical gap.

Color-Tunable CsCdCl3 Perovskite for Low-Temperature Anticounterfeiting and Information Storage Applications.

Low-temperature anticounterfeiting technologies play a crucial role in ensuring the authenticity and integrity of temperature-sensitive products such as vaccines, pharmaceuticals, and food items. In this work, a low-temperature anticounterfeiting route based on the differentiated photoluminescence (PL), PersL, and thermally stimulated luminescence (TSL) behaviors of metal halide perovskite, pure CsCdCl3, and CsCdCl3:10% Te4+ is proposed. The CsCdCl3 host exhibits pronounced color shifts, encompassing PL, PersL, and TSL behaviors, ranging from blue to yellow and orange as the temperature rises from 100 K to room temperature. This color change is attributed to a change in the luminous center (from the D3d octahedron to the C3v octahedron). Conversely, the addition of Te4+ as the luminescence center inhibits the matrix emission, maintains the characteristic orange emission of Te4+, and regulates the trap distribution of the matrix at low temperature and the TL luminescence intensity. This work highlights the significant promise of CsCdCl3:10% Te4+ and CsCdCl3 phosphors as innovative low-temperature anticounterfeiting technologies, especially for cold-chain vaccine safety monitoring.

Spin-coated BiFeO3 films on Si wafers: Low processing temperature but prominent piezoelectricity

The direct integration of crystalline oxide layers with industrial Si substrate, specifically compatible with CMOS technology, requires the development of relatively simple, low-temperature processing routes below 450 °C. Here, a novel nonstoichiometric approach is proposed to achieve fabrication of BiFeO3 films at 450 °C. Of particular importance is that, a saturation and remnant polarization of ∼80 μC/cm2 and ∼60 μC/cm2 and a strain as large as 1% are obtained. This strain stands as one of the most impressive values reported for thin films, comparable to the most superior strain obtained in ferroelectric films fabricated at temperatures exceeding 700 °C. The current work provides a new paradigm with significant simplicity and novel efficacy in reducing processing temperatures, as well offers a promising material for memory and piezo-driven actuating applications, especially meeting the increasing demand for precision position control systems at the nanometer scale.

Low-temperature solvent-free synthesis route of blue and green luminescent phases of tris(8-hydroxyquinoline)aluminum (AlQ3)

Recent research studies have shifted towards simple, efficient, and more eco-friendly synthesis methods. The current study focuses on using a free-solvent reaction to synthesize trichelate 8-hydroxyquinoline (8HQ) octahedral Al(III) coordination complex (AlQ3), which still represents the most widely used electroluminescent material in organic light-emitting devices (OLEDs). We have developed a new safe and easy route for synthesizing AlQ3 via a pure solid-state reaction between 8HQ and AlCl3 with sodium carbonate as an inorganic base. The formation of the free-solvent prepared AlQ3 was confirmed using FT-IR, UV–Vis spectroscopy, SEM/EDS analysis, powder, and single crystal. Our investigation overturns the belief that fac-AlQ3 is only formed at high temperature; the developed synthesis method enabled the production of blue-fluorescent AlQ3 at room temperature. Furthermore, this study presents a low-temperature synthesis pathway for obtaining pure AlQ3 phases for the first time. We controlled the washing step of the isolated AlQ3 to produce large amounts of blue and green luminescent AlQ3. The optical properties of the samples were determined using photoluminescence (PL) spectroscopy.

Monolithic three-dimensional tier-by-tier integration via van der Waals lamination.

Two-dimensional (2D) semiconductors have shown great potential for monolithic three-dimensional (M3D) integration due to their dangling-bonds-free surface and the ability to integrate to various substrates without the conventional constraint of lattice matching1-10. However, with atomically thin body thickness, 2D semiconductors are not compatible with various high-energy processes in microelectronics11-13, where the M3D integration of multiple 2D circuit tiers is challenging. Here we report an alternative low-temperature M3D integration approach by van der Waals (vdW) lamination of entire prefabricated circuit tiers, where the processing temperature is controlled to 120 °C. By further repeating the vdW lamination process tier by tier, an M3D integrated system is achieved with 10 circuit tiers in the vertical direction, overcoming previous thermal budget limitations. Detailed electrical characterization demonstrates the bottom 2D transistor is not impacted after repetitively laminating vdW circuit tiers on top. Furthermore, by vertically connecting devices within different tiers through vdW inter-tier vias, various logic and heterogeneous structures are realized with desired system functions. Our demonstration provides a low-temperature route towards fabricating M3D circuits with increased numbers of tiers.

La implanted band engineering of ZnO nanorods for enhanced photoelectrochemical water splitting performance

In the quest to improve photoelectrochemical water-splitting performance, we have doped lanthanum (La) in highly crystalline zinc oxide (ZnO) nanorods (NRs) using a facile and low-temperature hydrothermal route and successful substitution of La3+ at the Zn2+ site is confirmed from structural and chemical analysis. The tapered NRs morphology gained after La doping resulted in lower optical bandgap of 3.17 eV, enhanced visible light trapping, and multiphoton absorption, which assist in achieving good PEC activity. The La doping also offered higher Urbach energy (EU), subsidizing the number of oxygen vacancies. The UPS spectra show that La doping reduces conduction band energy level and endorses smooth charge transportation. The La-doped ZnO exhibits two times enhancement in photocurrent (1.54 mA·cm−2) compared to pristine ZnO (0.81 mA·cm−2). The higher applied bias to the photon conversion efficiency of ∼1.14% for La-doped ZnO confirms the efficient utilization of solar energy. The EIS measurements demonstrated reduction in charge transfer resistance with La-doping. Mott-Schottky analysis shows that La doping lowers the flat-band potential and enhances charge transportation, making it a potential photoanode for PEC water-splitting applications.

Synthesis, Structure, and Properties of CuBiSeCl2: A Chalcohalide Material with Low Thermal Conductivity.

Mixed anion halide-chalcogenide materials have recently attracted attention for a variety of applications, owing to their desirable optoelectronic properties. We report the synthesis of a previously unreported mixed-metal chalcohalide material, CuBiSeCl2 (Pnma), accessed through a simple, low-temperature solid-state route. The physical structure is characterized through single-crystal X-ray diffraction and reveals significant Cu displacement within the CuSe2Cl4 octahedra. The electronic structure of CuBiSeCl2 is investigated computationally, which indicates highly anisotropic charge carrier effective masses, and by experimental verification using X-ray photoelectron spectroscopy, which reveals a valence band dominated by Cu orbitals. The band gap is measured to be 1.33(2) eV, a suitable value for solar absorption applications. The electronic and thermal properties, including resistivity, Seebeck coefficient, thermal conductivity, and heat capacity, are also measured, and it is found that CuBiSeCl2 exhibits a low room temperature thermal conductivity of 0.27(4) W K-1 m-1, realized through modifications to the phonon landscape through increased bonding anisotropy.

Low-temperature synthesis of transparent conducting La-doped BaSnO3via rejuvenation of the dried peroxo-precursor

In this article, we develop a low-temperature route for the synthesis of the high figure-of-merit transparent conductor, La-doped BaSnO3. Towards this, we first study the evolution of the cubic perovskite phase of the undoped BaSnO3 during solution combustion synthesis. A peroxo/superoxo precursor synthesized via H2O2 assisted co-precipitation is employed as the oxidizing agent. Typically, precursor drying is detrimental to the low-temperature conversion of the precursor to crystalline BaSnO3. The synthesis procedure developed herein is agnostic to the altered precursor composition obtained under the particular drying conditions. This is achieved by re-solvation of the precursor with ethyl alcohol prior to the annealing. The added ethanol plays the role of fuel, enabling an exothermic reaction of the components of the mixture, providing the heat of reaction for conversion and crystal growth. Complete conversion of the precursor to phase-pure BaSnO3 with a three-fold increase in the crystallite size at lower temperatures is thus achieved. We then demonstrate the facile incorporation of lanthanum as a dopant through this method. The low-temperature synthesized lanthanum substituted BaSnO3 displays optical absorption in the NIR region corresponding to free carrier generation, and n-type conductivity.

Phase formation, microstructural and dielectric properties of bismuth ferrite nanoceramics synthesized by low-temperature molten salt flux route

BiFeO3 nano-ceramics were synthesized using the low-temperature molten salt synthesis route to study the influence of calcination temperature and salt ratios. The Rietveld refinement revealed the distorted perovskite structure of BFO. These granular-shaped BFO samples’ grains morphology was studied using the FESEM. The FTIR revealed the presence of Metal-Oxygen bonds in the BFO ceramics. The XPS studies exhibited the respective constituent elements’ oxidation states and validated the presence of oxygen ion vacancies. The frequency-dependent dielectric properties were measured at various temperatures. The electrical conductivity measurement showed a linear variation as a function of frequency which validated Jonscher’s power law.

Fe-doping on CaV2O6 for oxygen vacancy controlling lithium storage

Currently, alkaline earth metal vanadates as the anode materials for lithium-ion batteries (LIBs) are gradually sparking attention due to their low cost, environmental friendliness, high theoretical capacity and safety. However, their practical application is still hampered by the fast capacity degradation resulting from the prolonged cycling condition and intrinsic low electrical conductivity. Herein, single-crystal Fe-doped CaV2O6 is prepared via the low-temperature combustion synthesis route. The Fe-doping accelerates the generation of low-valence-state vanadium in CaV2O6–2%Fe, leading to the production of oxygen vacancies for maintaining electroneutrality. The versatile design of CaV2O6–2%Fe improves the electron conductivity and promotes the Li-ion diffusion rate based on the generated dual defects of interstitial atoms of Fe and oxygen vacancies accordingly. As expected, the CaV2O6–2%Fe electrode exhibits superior rate capacity of 96.6 mA h g−1 at 5 A g−1 and a remarkable capacity retention of 125.6 mA h g−1 after 1000 cycles at 1 A g−1. Additionally, the partial decomposition of CaV2O6 during the initial lithiation stage, and the formation of amorphous Li–V–O in the subsequent cycle can be used to depict the lithium storage mechanism of CaV2O6–2%Fe.

Tetragonal phase-free crystallization of highly conductive nanoscale cubic garnet (Li6.1Al0.3La3Zr2O12) for all-solid-state lithium-metal batteries

The synthesis and processing of garnet-type conductors is usually done at temperatures above 1100 °C to reach the high Li-ion conducting cubic phase resulting in micron-sized particles and potential Li-loss, which are unfavorable for further processing and electrode-electrolyte assembly. Here, we tackle this problem and report a novel low-temperature aqueous synthesis route to stabilize the cubic phase of Li6.1Al0.3La3Zr2O12 (c-Al-LLZO) at a temperature as low as 600 °C, while obtaining nano-crystallites at around 100 - 200 nm. Moreover, a dual-reaction mechanism was proposed to describe the process of c-Al-LLZO crystallization. The as-synthesized nanoscale c-Al-LLZO particles facilitate the densification of the solid-state electrolyte (SSE) pellets with less endowed grain boundaries (exhibiting a high relative density of 97.8 %). The ionic conductivity reaches 0.42 mS cm−1 at 21 °C and the low activation energy (half of the published values) is 0.17 eV. The results presented here show that symmetric cells with Li metal exhibit excellent stability at the current density of 0.2 mA/cm2 and 0.5 mA/cm2, and an improved critical current density (CCD) of 2.16 mA/cm2. This work provides a feasible method of low-temperature crystallization of nanoscale cubic garnet SSEs with good performance for the fabrication of stable SSLBs.

Morphology-controlled synthesis of novel nanostructured Li4P2O7 with enhanced Li-ion conductivity for all-solid-state battery applications.

Mechanical stiffness of oxide-type solid-electrolytes is a major drawback which has hindered their practical application in all-solid-state Li-ion batteries to date. Despite their enhanced structural and electrochemical stabilities, lack of deformability of fast-ion conducting oxides impedes the integration of these materials in bulk-type solid-state cells. Deformable solid-electrolytes such as sulfides, on the other hand, lack sufficient electrochemical stability in contact with conventional cathodes. This has recently triggered a search for new materials that combine high ion-conductivity, deformability and sufficient electrochemical stability. Here, we report the synthesis of a novel form of Li4P2O7 that can be densified by cold-pressing and possesses an ion conductivity that is two orders of magnitude higher than conventional Li4P2O7 phases. The material is synthesized by a combination of microwave synthesis and chemical lithiation and adopts a nanostructured morphology with a small amorphous component. The material is electrochemically stable at voltages >5 V vs. Li+/Li, which suggests safe use with high-voltage cathodes. The newly-synthesized material is therefore a bulk, deformable analogue of LiPON, with comparable ion conductivity and phase stability. This research highlights the potential of using novel low-temperature synthetic routes to control the morphology and enhance the electrochemical performance of conventional functional materials.

A low-temperature self-flux route to prepare hexagonal rare earth fluorides and manipulation of upconversion luminescence in rodlike NaYbF4:Tm3+/Fe3+ crystals

The distorted lattice, ET between Tm3+ and Fe3+ and no ET between Yb3+ and Fe3+ make 89Yb1Tm10Fe crystals obtained in low-temperature self-flux system exhibit the strongest emission with its absolute UCQY of 0.46% and of 0.56% with and without the magnetic field of 15 kOe, respectively.