Formation Enthalpy Calculation of Oxygen Vacancy Defect in Doped Lithium Niobate Crystals

The relationship between temperature and oxygen vacancy concentration is deduced in this paper. Based on the data of thermal weight-loss experiment, the formation enthalpies of congruent and several doped LN crystals have been calculated. It was found that the formation enthalpy of oxygen vacancies can be decreased evidently by doping valence-changeable ions. The experimental results were discussed and a new reduction process of the photorefractive LN crystal at a relatively low temperature was proposed, and the reduced crystals showed a good effect in practical use.

Synthesis and Characterization of Cubic Zinc Titanate Doped with Lithium

Cubic （Zn,Li）TiO3 powders were synthesized through a modified sol-gel route including the Pechini process via a three-step heat treatment.The as-synthesized （Zn,Li）TiO3 could be stable up to 1000 °C.The dielectric constant and dielectric loss tangent of all the synthesized （Zn,Li）TiO3 samples at different measurement frequencies showed the similar tendency.At the same frequency,the dielectric constant and the dielectric loss tangent of （Zn,Li）TiO3 samples decreased and increased,respectively,with the lithium doping content increase.The as-prepared （Zn,Li）TiO3 showed improved microwave dielectric properties,and its maximum value of quality factor could reach 34000 GHz.

Enhanced thermoelectric performance in p-type Mg3Sb2 via lithium doping

The Zintl compound Mg3Sb2 has been recently identified as promising thermoelectric material owing to its high thermoelectric performance and cost-effective,nontoxicity and environment friendly characteristics.However,the intrinsically p-type Mg3Sb2 shows low figure of merit（z T = 0.23 at 723 K） for its poor electrical conductivity.In this study,a series of Mg（3-x）LixSb2 bulk materials have been prepared by high-energy ball milling and spark plasma sintering（SPS） process.Electrical transport measurements on these materials revealed significant improvement on the power factor with respect to the undoped sample,which can be essentially attributed to the increased carrier concentration,leading to a maximum z T of0.59 at 723 K with the optimum doping level x = 0.01.Additionally,the engineering z T and energy conversion efficiency are calculated to be 0.235 and 4.89%,respectively.To our best knowledge,those are the highest values of all reported p-type Mg3Sb2-based compounds with single element doping.

Recovery of lithium using H_(4)Mn_(3.5)Ti_(1.5)O_(12)/reduced graphene oxide/polyacrylamide composite hydrogel from brine by Ads-ESIX process

Powdery Li^(+)-imprinted manganese oxides adsorbent was widely used to the recovery of Li^(+),but there are some difficulties,such as poor stability in acid solution,inconvenience of operation and separation.In this work,a useful hydrogel composite based H_(4)Mn_(3.5)Ti_(1.5)O_(12)/reduced graphene oxide/polyacrylamide(HMTO-rGO/PAM)was fabricated by thermal initiation method with promising stable,conductive and selective properties.The resulting materials were characterized by field emission scanning electron microscope,infrared absorption spectrum,X-ray diffraction,X-ray photoelectron spectroscopy and electrochemical techniques.The recovery of Li^(+)was investigated using HMTO-rGO/PAM from brine by a separated two-stage sorption statically and electrically switched ion exchange desorption process.The adsorption capacity of 51.5 mg·g^(-1)could be achieved with an initial Li^(+)concentration of 200 mg·L^(-1)in pH 10,at 45℃ for 12 h.Li^(+)ions could be quickly desorbed by cyclic voltammetry(CV)in pH 3,0.1 mol·L^(-1)HCl/NH;Cl accompanying the exchange of Li^(+)and H+(NH;)and the transfer of LMTO-rGO/PAM to HMTO-rGO/PAM.

Osteogenic lithium-doped brushite cements for bone regeneration

This study investigated the osteogenic performance of new brushite cements obtained from Li+-dopedβ-tricalcium phosphate as a promising strategy for bone regeneration.Lithium(Li+)is a promising trace element to encourage the migration and proliferation of adipose-derived stem cells(hASCs)and the osteogenic differentiation-related gene expression,essential for osteogenesis.In-situ X-ray diffraction(XRD)and in-situ 1H nuclear magnetic resonance(1H NMR)measurements proved the precipitation of brushite,as main phase,and monetite,indicating that Li+favored the formation of monetite under certain conditions.Li+was detected in the remaining pore solution in significant amounts after the completion of hydration.Isothermal calorimetry results showed an accelerating effect of Li+,especially for low concentration of the setting retarder(phytic acid).A decrease of initial and final setting times with increasing amount of Li+was detected and setting times could be well adjusted by varying the setting retarder concentration.The cements presented compressive mechanical strength within the ranges reported for cancellous bone.In vitro assays using hASCs showed normal metabolic and proliferative levels.The immunodetection and gene expression profile of osteogenic-related markers highlight the incorporation of Li+for increasing the in vivo bone density.The osteogenic potential of Li-doped brushite cements may be recommended for further research on bone defect repair strategies.

Electrochemical performance of interfacially polymerized polyaniline nanofibres as electrode materials for non-aqueous redox supercapacitors

H+ doped polyaniline nanofibre(PH) was synthesized by interfacial polymerization and polyanilines doped with Li salt(PLI and PHLI) were prepared by immersing emeraldine base(EB) and H+ doped polyaniline in 1 mol/L LiPF6/(EC-EMC-DMC),respectively.PH,PLI and PHLI were all characterized by scanning electron microscopy(SEM) and Fourier transform infrared(FT-IR) spectrometry.With 1 mol/L LiPF6/(EC-EMC-DMC) as electrolyte,PH,PHLI and PLI were used as the active materials of symmetric non-aqueous redox supercapacitors.PLI shows the highest initial specific capacitance of 120 F/g(47 F/g for PH and 66 F/g for PHLI) among three samples.After 500 cycles,the specific capacitance of PLI remains 75 F/g,indicating the good cycleability.

A nanoporous nitrogen-doped graphene for high performance lithium sulfur batteries

A nanoporous N-doped reduced graphene oxide（p-N-rGO） was prepared through carbothermal reaction between graphene oxide and ammonium-containing oxometalates as sulfur host for Li-S batteries.The p-N-rGO sheets have abundant nanopores with diameters of 10-40 nm and the nitrogen content is 2.65 at%.When used as sulfur cathode,the obtained p-N-rGO/S composite has a high reversible capacity of 1110mAhg^-1 at 1C rate and stable cycling performance with 781.8 mAhg-1 retained after 110 cycles,much better than those of the rGO/S composite.The enhanced electrochemical performance is ascribed to the rational combination of nanopores and N-doping,which provide efficient contact and wetting with the electrolyte,accommodate volume expansion and immobilize polysulfides during cycling.

Nd^(3+)-doped Li_3V_2(PO_4)_3 cathode material with high rate capability for Li-ion batteries

A series of Nd^3＋-doped LiNdxV2-x（PO4）3（x = 0.00, 0.02, 0.05, 0.08 or 0.1） composites are synthesized by the rheological phase reaction method. The XRD results indicate that Nd3＋ions have been successfully merged into a lattice structure. Doped samples show good electrochemical performance in high discharge rate and long cycle. In the potential range of 3.0–4.3 V, Li3Nd0.08V1.92（PO4）3exhibits an initial discharge capacity of 115.8 m Ah/g at 0.2 C and retain 80.86% of capacity retention at 2 C in the 51 st cycle.In addition, Li3Nd0.05V1.95（PO4）3holds at 100.4 m Ah/g after 80 cycles at 0.2 C with a capacity retention of92.4%. Finally, the CV test proves that the potential polarization of Li3Nd0.08V1.92（PO4）3decreased compared with the un-doped one.