A New One-dimensional Aluminium Fluorophosphate Templated by Organic Amine

A new one-dimensional aluminum fluorophosphate, AlP2O5（OH）3F·0.5[H2dien] （dien=diethylenetriamine）, was solvothermally synthesized by using organic amine as the structure directing agent, and its structure was determined by single-crystal X-ray diffraction. The complex inorganic architecture consists of trans-corner-sharing AlO4F2 octahedra chain decorated by phosphate tetrahedra along both sides of the -F-Al-F-Al-F- backbone displaying a series of Al2P three-membered rings, which will represent a new fundamental structural type in metal phosphates. The results of CHN elemental analysis, EDS, and TGA are also presented. Crystal data： C4H18Al2F2N3O16P4, monoclinic, space group P21/c with a=6.9107（14）, b=15.749（3）, c=8.9741（18） , β=109.829（2）o, V=918.8（3） 3, Z=2, Mr=580.05, Dc=2.097 g/cm3, μ=0.618 mm-1, S=1.022, F（000）=590, the final R=0.0510 and wR=0.1284 for 1607 observed reflections （I 〉 2σ（I））.

Spectroscopic properties in Er^(3+)/Yb^(3+) Co-doped fluorophosphate glass

Using the technique of high-temperature melting, a new Er3＋/Yb3＋ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er3＋ and Yb3＋ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd Ofelt theory, the oscillator strength was computed. The lifetime of 4113/2 level （t-m） of Er3＋ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 μm. The large stimulated emission cross section of the Er3＋ was calculated by the McCumher theory. The spectroscopic properties of Er3＋ ion were compared with those in different glasses. The full width at half maximum and σe are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.

Structure and Properties of Poly (ethylene terephthalate)/Tin Fluorophosphate Glass Hybrids

Poly(ethylene terephthalate)(PET)/tin fluorophosphate glass(Pglass) hybrids were prepared via melt blending in the present paper,and the phase morphology,dynamic rheology,crystallization behavior,dynamic and static mechanical properties,and thermal stability of the hybrids have been investigated.Scanning electron microscopy(SEM) and transmission electron microscopy(TEM) showed the Pglass particles well dispersed in the PET matrix within a nanoscale.The results showed that the addition of Pglass induced some advantages on the properties of PET matrix,such as the decreasing of melt viscosity,increasing the isothermal crystallization rate and crystallinity,and improving the storage modulus and elasticity modulus.

Fluorophosphates and fluorosulfates cathode materials: Progress towards high energy density sodium-ion battery

The rapid diffusion of renewable energy boosts the wide deployment of large-scale energy storage system.With the low cost and high crustal abundance,sodium-ion battery(SIB)technology is expected to become a dominant technology in that area in the future.Toward the practical application,novel cathode materials are urged to develop that show high energy density without sacrificing their cost and benignity to the environment.While the years of many studies,this still remains a huge challenge to battery scientists.In this review,we discuss recent breakthroughs in SIB cathode materials with high energy density,namely fluorphosphates and fluorosulfates.The design of materials,the crystal structure,the electrochemical performance,and the underlaying intercalation mechanism are systematically reviewed.Useful strategies and research directions are also provided to advance future high-energy,low-cost,and ecofriendly cathode materials for next generation SIB.

Nano self-assembly of fluorophosphate cathode induced by surface energy evolution towards high-rate and stable sodium-ion batteries

In the field of materials science and engineering,controlling over shape and crystal orientation remains a tremendous challenge.Herein,we realize a nano self-assembly morphology adjustment of Na3V2(PO4)2F3(NVPF)material,based on surface energy evolution by partially replacing V3+with aliovalent Mn2+.Crystal growth direction and surface energy evolution,main factors in inducing the nano self-assembly of NVPF with different shapes and sizes,are revealed by high-resolution transmission electron microscope combined with density functional theory.Furthermore,NVPF with a two-dimensional nanosheet structure(NVPF-NS)exhibits the best rate capability with 68 mAh·g−1 of specific capacity at an ultrahigh rate of 20 C and cycle stability with 80.7%of capacity retention over 1,000 cycles at 1 C.More significantly,when matched with Se@reduced graphene oxide(rGO)anode,NVPF-NS//Se@rGO sodium-ion full cells display a remarkable long-term stability with a high capacity retention of 93.8%after 500 cycles at 0.5 C and−25°C.Consequently,experimental and theoretical calculation results manifest that NVPF-NS demonstrates such superior performances,which can be mainly due to its inherent crystal structure and preferential orientation growth of{001}facets.This work will promise insights into developing novel architectural design strategies for high-performance cathode materials in advanced sodium-ion batteries.

Synthesis and optical properties of novel apatite-type NaCa_(3)Bi(PO_(4))_(3)F:Dy^(3+)yellow-emitting fluorophosphate phosphors for white LEDs

In this study,novel yellow-emitting fluorophosphate NaCa_(3)Bi(PO_(4))_(3)F phosphors doped with different concentrations of Dy^(3+)ions were first obtained via high-temperature solid-state reaction.The crystal structure,phase purity,particle morphology,photoluminescence(PL)properties,thermal stability,and luminescence decay curves of the resulting phosphors were then characterized in detail.Under the excitation of 349 nm,the three dominant peaks of the NaCa_(3)Bi(PO_(4))_(3)F:Dy^(3+)are centered at 480 nm(^(4)F_(9/2)-^(6)H_(15/2)),577 nm(^(4)F_(9/2)-^(6)H_(13/2)),and 662 nm(^(4)F_(9/2)-^(6)H_(11/2)).The optimal doping concentration of Dy^(3+)ions in the NaCa_(3)Bi(PO_(4))_(3)F:xDy^(3+)phosphors is x=5 mol%.The phosphors show excellent thermal stability with high activation energy(Ea=0.32 eV).Eventually,the synthesized white lightemitting diode(w-LED)demonstrates the Commission International de L’Eclairage(CIE)chromaticity coordinates of(0.341,0.334),a good correlated color temperature(CCT)of 5083 K,and a high color rendering index(Ra)of 92.Revealing its potential as yellow-emitting phosphors,the feasibility of the fabricated apatite-type NaCa_(3)Bi(PO_(4))_(3)F:Dy^(3+)fluorophosphate phosphors was confirmed for wLEDs.

Realizing high-performance Na_(3)V_(2)(PO_(4))_(2)O_(2)F cathode for sodium-ion batteries via Nb-doping

Na_(3)V_(2)(PO_(4))_(2)O_(2)F(NVPOF)has received considerable interest as a promising cathode material for sodium-ion batteries because of its high working voltage and good structural/thermal stability.However,the sluggish electrode reaction resulting from its low intrinsic electronic conductivity significantly restricts its electrochemical performance and thus its practical application.Herein,Nb-doped Na_(3)V_(2-x)Nb_(x)(PO_(4))_(2)O_(2)F/graphene(rGO)composites(x=0,0.05,0.1)were prepared using a solvothermal method followed by calcination.Compared to the un-doped NVPOF/r GO,doping V-site with high-valence Nb element(Nb^(5+))(Na_(3)V_(1.95)Nb_(0.05)(PO_(4))_(2)O_(2)F/r GO(NVN05POF/rGO))can result in the generated V4^(+)/V3^(+)mixed-valence,ensuring the lower bandgap and thus the increased intrinsic electronic conductivity.Besides,the expanded lattice space favors the Na^(+)migration.With the structure feature where NVN05POF particles are attached to the rGO sheets,the electrode reaction kinetics is further accelerated owing to the well-constructed electron conductive network.As a consequence,the as-prepared NVN05POF/r GO sample exhibits a high specific capacity of~72 m Ah·g^(-1)at 10C(capacity retention of 65.2%(vs.0.5C))and excellent long-term cycling stability with the capacity fading rate of~0.099%per cycle in 500 cycles at 5C.

Plum pudding model inspired KVPO4F@3DC as high-voltage and hyperstable cathode for potassium ion batteries

The investigation on the cathode material of potassium ion batteries(PIBs),one of the most promising alternatives to lithium ion batteries,is of great significance.Potassium vanadium fluorophosphate(KVPO4F)with a high working voltage is an appealing cathode candidate for PIBs,while the poor cycling performance and low electronic conductivity dramatically hinder the application.Herein,a plum pudding model inspired three-dimensional amorphous carbon network modified KVPO4F composite(KVPO4F@3DC)is successfully designed in this study to tackle these problems.In the composite,KVPO4F particles are homogeneously wrapped by a layer of amorphous carbon and bridged by crosslinked large area carbon sheets.As the cathode for PIBs,the KVPO4F@3DC composite exhibits a high average operating voltage about 4.10 V with a super-high discharge capacity of 102.96 mAh g^-1 at 20 mA g^-1.An excellent long cycle stability with a capacity retention of 85.4%over 550 cycles at 500 mA g^-1 is achieved.In addition,it maintains 83.6%of its initial capacity at 50 mA g^-1 after 100 cycles at 55℃.The design of KVPO4F@3DC with plum pudding structure provides facilitative electron conductive network and stable electrode/electrode interface for electrode,successfully innovating an ultra-stable and high-performance cathode material for potassium ion batteries.

Research and development of new neodymium laser glasses

This work presents a brief introduction on three kinds of newly developed Nd^(3+)-doped laser glasses in Shanghai Institute of Optics and Fine Mechanics(SIOM), China. Two Nd^(3+)-doped phosphate glasses with lower thermal expansion coefficient and thermal shock resistance 4 times higher than that of N31 glass are developed for laser processing.Nd:Silicate and Nd:Aluminate glasses with peak emission wavelength at 1061 and 1065 nm, effective emission bandwidth of 34 and 50 nm, respectively, are developed for Exawatt-class laser system application. Fluorophosphate glasses with low nonlinear refractive index(n_2=0.6–0.86) and long fluorescence lifetime(430–510 μs) are investigated for the purpose of decreasing B integral in high-power laser system. The properties of all these glasses are presented and compared with those of commercial neodymium laser glasses.

Phase-pure Na3V2(PO4)2F3 embedded in carbon matrix through a facile polyol synthesis as a potential cathode for high performance sodium-ion batteries

In this study,a pseudo-layered Na super-ionic conductor of Na3V2(PO4)2F3 (NVPF)/C cathode for sodium-ion batteries is prepared successfully using a facile polyol refluxing process without any impurity phases.The X-ray diffraction and Rietveld refinement results confirm that NVPF possesses tetragonal NASICON-type lattice with a space group of P42/mnm.In this preparative method,polyol is utilized as a solvent as well as a carbon source.The presence of nanosized NVPF particles in the carbon network is confirmed by field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM).The existence of carbon is analyzed by Raman scattering and elemental analysis.When applied as a Na-storage material in a potential window of 2.0-4.3 V,the electrode exhibits two flat voltage plateaus at 3.7 and 4.2 V with an electrochemically active V^3+/V^4+ redox couple.In addition,Na3V2(PO4)2F3/C composite achieved a retention capacity of ~ 88% even after 1,500 cycles at 15 C.Moreover,at high current densities of 30 and 50 C,Na3V2(PO4)2F3/C cathode retains the specific discharge capacities of 108.4 and 105.9 mAh·g-1,respectively,revealing the structural stability of the material prepared through a facile polyol refluxing method.

Rapid microwave-assisted refluxing synthesis of hierarchical mulberry-shaped Na_3V_2(PO_4)_2O_2F@C as high performance cathode for sodium & lithium-ion batteries

Unique hierarchical mulberry-shaped Na3V2(PO4)2O2F@C nanocomposite was fabricated by a rapid microwave-assisted low-temperature refluxing strategy. The V(acac)3 reverse micelle systems in the water-in-oil microemulsions played key roles in forming the self-assembly architectures. The prepared Na3V2(PO4)2O2F@C nanoparticles with the anisotropic growth along the [002] direction were in-situ encapsulated in carbon shells, which greatly contribute to fast Na+/e-transfer in electrodes. And the self-assemblies with high structure stability help to improve the cycle performance and mitigate voltage fading. The initial discharge capacity of Na3V2(PO4)2O2F@C as cathode for sodium ion batteries is about 127.9 m A h g-1 at 0.1 C. Besides, a high rate performance with a capacity of 88.1 mA h g-1 at 20 C has been achieved, and the capacity retains 82.1% after 2,000 cycles. In addition, the reaction kinetics and Na+ transportation mechanism of Na3V2(PO4)2O2F@C were preliminarily investigated by the ex situ X-ray diffraction, X-ray photoelectron spectroscopy and galvanostatic intermittent titration technique. More interestingly, when coupled with Li, the fabricated hybrid Li/Na-ion batteries also exhibit excellent rate and cycling performances. The proposed rapid refluxing strategy to synthesize mulberry-shaped Na3V2(PO4)2O2F@C opens up a new opportunity to develop high-performance electrode materials for the energy storage systems.

Fast and stable Mg^2+ intercalation in a high voltage NaV2O2(PO4)2F/rGO cathode material for magnesium-ion batteries

Sluggish kinetics of Mg^2+intercalation and low working potential seriously hinder the development of highenergy-density magnesium-ion batteries(MIBs).Hence developing cathode materials with fast Mg^2+diffusion and high working voltage is a key to overcome the obstacles in MIBs.Herein,a tetragonal NaV2O2(PO4)2 F/reduced graphene oxide(r GO)is proposed as an effective Mg^2+host for the first time.It exhibits the highest average discharge voltage(3.3 V vs.Mg^2+/Mg),fast diffusion kinetics of Mg^2+with the average diffusivity of 2.99×10^-10 cm^2s^-1,and ultralong cycling stability(up to 9500 cycles).The Mg^2+storage mechanism of NaV2O2(PO4)2 F/r GO is demonstrated as a single-phase(de)intercalation reaction by in situ X-ray diffraction(XRD)technology.Density functional theory(DFT)computations further reveal that Mg^2+ions tend to migrate along the a direction.X-ray absorption near edge structure(XANES)demonstrates a decrease in the average valence of vanadium,and the local coordination environment around vanadium site is highly conserved after magnesiation.Moreover,the assembled NaV2O2(PO4)2 F//Mg0.79NaTi2(PO4)3 Mg-ion full cell exhibits high power and energy densities,which indicates that NaV2O2(PO4)2 F/r GO owns potential for practical applications.This work achieves a breakthrough in the working voltage of cathode materials for MIBs and provides a new opportunity for high-energy-density MIBs.

Synthesis/Structure and Cathode Properties of Li_2CoPO_4F for High-Voltage Li-ion Batteries

1 Results Although phospho-olivine LiFePO4 has attracted much attention as next-generation cathode, the gravimetric energy density is restricted. Fluorophosphate Li2CoPO4F is strong candidate for new high-voltage cathode with large capacity,if 2 Li+ can be reversibly removed[1]. In the present study, we tried to synthesized Li2CoPO4F by two methods, solid state reaction in vacuumed quartz tube with Pt crucible and melt-quench process using Cu single roller in Ar. The obtained latter amorphous sample was...