High-temperature Solid-phase Method Research Articles

Multifunctional rare earth ions-doped Ba2LaF7 nanocrystals for simultaneous temperature sensing and photothermal therapy

As an urgent problem, cancer has boosted the development and application of many treatment technologies in biomedicine. Photothermal therapy with precise control for tumors has gained more and more attention as a promising technology in biomedical fields. In this work, rare earth ions-doped Ba2LaF7 nanocrystals have been successfully developed by the high-temperature solid-phase method as the core material in a multi-functional system. Optical temperature measurement based on fluorescence intensity ratio improves sensitivity by widely separating Er3+ and Nd3+ emission bands. Meanwhile, the relative sensitivity increases with increasing temperature. From the comparison between the fitting curve and the actual temperature, it can be concluded that the nanocrystals have a good photothermal response to the laser pumping power and can even be used for photothermal imaging. On this basis, to study its optical measurement and photothermal conversion performance, we made a multifunctional system acting on biological tissues. The results suggest that the developed material has a potential application in bio-targeted photothermal therapy.

Synthesis and photoluminescence properties of a novel green-emitting LiYGeO4 :Tb3+ long afterglow phosphor.

A new green luminescent phosphor, Li(Y1-x Tbx )GeO4 , was prepared using a high-temperature solid-phase method. The X-ray diffraction (XRD) measured spectrum agreed well with the standard card JCPDS No. 02-3479, indicating that it is a quaternary compound belonging to the space group of Pnma(62) with an orthogonal crystalline phase; the excitation and emission spectra measured using the phosphor spectrometer showed that it can be effectively excited by near-ultraviolet light at 378 nm and blue light at 482 nm, and produced excellent strong emission of green light at 550 nm. The afterglow test results show that the sample had a good long afterglow effect at lower doping concentrations; the thermal stability test results showed that its thermal burst activation energy ΔE ≈ 0.37 eV had its excellent thermal stability. The rare earth Tb3+ -doped green phosphor, LiYGeO4 :Tb3+ , has potential applications in household lighting, medical therapy, and optical storage.

Enhancing battery performance by glucose addition to form spherical Li4Ti5O12 as an anode material

A high specific capacity spherical Li4Ti5O12 anode material of Lithium-Ion battery was successfully synthesized by a high-temperature solid-phase method consisting of ball milling, spray drying and calcination processes. Its suitable reaction conditions were explored by the orthogonal experiment method, and the effect of glucose addition on the morphology and electrochemical performance of Li4Ti5O12 was studied. The addition of glucose could change the surface structure of Li4Ti5O12, improve its conductivity, therefore enhance its electrochemical performance. The prepared lithium titanate represents a superior specific capacity of 163 mAh·g−1 at 0.2 C rates, approximately 65 mAh·g−1 under 10 C rates, and the capacity retention rate of sample remained 97.55% after 100 cycles of charging/discharging process.

Nanorod-sphere hybrid MnOx synthesized by a simple thiourea reduction of MnO2 for long lifespan aqueous zinc-ion batteries

• Nanorod-sphere hybrid MnOx was successfully synthesized by a mild reaction of MnO 2 with thiourea. • A large number of oxygen vacancies was introduced in MnOx to accelerate the electrochemical kinetics. • The as prepared MnOx shows superior cycling stability than the pristine MnO 2 . Although many reports have improved the electrochemical performance from the perspective of changing the nanostructure of MnO 2 , such as the hydrothermal method and high temperature solid phase method, few studies modulate the morphology of MnO 2 at low temperature. In this work, the nanorod-sphere hybrid MnO x with better cycling stability was successfully synthesized by thiourea reduction of low crystallinity MnO 2 . The oxygen defects introduced by thiourea reduction accelerate the electrochemical kinetics and effectively improve its cycle stability. The MnO x exhibits enhanced cycling stability with 78.9% capacitance retention compared with that of pristine MnO 2 (3.9%).

Structure and luminescence properties of Bi3+-doped ZrSiO4 phosphors for near-UV excited white LEDs

• A novel ZrSiO 4 :Bi 3+ phosphor has been synthesized. • The ZrSiO 4 :Bi 3+ samples exhibit broad emission bands peaked at 548 nm when excited at 361 nm. • The ZrSiO 4 :Bi 3+ phosphors own excellent thermal stability. • The luminescence mechanisms and energy transfer processes are discussed. ZrSiO 4 :Bi 3+ phosphors were synthesized by conventional high-temperature solid-phase method. The structural and optical behaviors were investigated by X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy and photoluminescence spectra. Bi 2 O 3 contributes to the ZrSiO 4 phase generation from liquid phase sintering. The ZrSiO 4 :Bi 3+ shows a broad emission band centered at 548 nm when excited at 361 nm. The Bi 3+ doping concentration is optimized to be 4 mol%, and the luminescence intensity of ZrSiO 4 :0.04Bi 3+ at 150 °C keeps 84% of that at room temperature. The results indicate that the ZrSiO 4 :Bi 3+ phosphors offer more possibilities in the near-UV excited white LED applications.

Synthesis and photoluminescence performance of single-component Ca3YAl3B4O15:Dy3+, Eu3+ white-emitting phosphor for white light-emitting diodes

A single-component Ca3YAl3B4O15 (CYAB):Dy3+, Eu3+ phosphor was synthesized by the traditional high temperature solid-phase method, Dy3+ and Eu3+ were codoped in the structure to obtain a warm white emission. The results of XRD and EDS revealed that all samples had the standard Ca3YAl3B4O15 structure, and no impurity phase appeared with codoping. The emission of Dy3+ in CYAB consisted of both main peaks at 476 nm and 570 nm, with which a white emission could be observed. Furthermore, a characteristic emission peak of Eu3+ appeared at 617 nm in Dy3+/Eu3+-codoped samples to supplement red component for the white emission of Dy3+, due to the energy transfer effect between Dy3+ and Eu3+. With the amount of Eu3+ raised, the correlated colour temperature of CYAB:Dy3+, Eu3+ phosphor obviously decreased, and a warm white light was successfully realized from the manufactured w-LEDs. Therefore, all results indicated that the single-component Dy3+/Eu3+ codoped CYAB white-emitting phosphor had a potential application in ultraviolet excited w-LEDs.

Rare earth tungstate high-entropy ceramic powders containing holmium with broad-spectrum antibacterial and antiviral activity

A2W3O12-type (A=La, Sm, Eu, Gd, RE) rare earth tungstate high-entropy ceramic powder with a positively charged surface was fabricated by a high-temperature solid-phase method, and its antibacterial and antiviral properties were evaluated for the first time. Changes in the antibacterial and antiviral activity and ionic solubility of these compounds induced by changing the RE element at the A-position were investigated. The A2W3O12 high-entropy ceramic powder was a stable surface antibacterial material. Its antimicrobial properties are not affected by light and environmental acids and bases. The (La0.2Sm0.2Eu0.2Gd0.2Ho0.2)2W3O12 high-entropy ceramic powder had the best antibacterial performance in the absence of light, and the killing rate was more than 99.9% for both Staphylococcus aureus and Escherichia coli. On this basis, the animal viruses H1N1 influenza virus (enveloped) and EV71 enterovirus (nonenveloped) were selected for antiviral testing, and the survival rate of both viruses decreased by more than 99% within 2 h. The powder was evaluated for ion solubilization under acidic and alkaline service conditions, showing low ion solubilization and superior environmental suitability.

Study on energy transfer mechanism and optical properties of LiLaSiO4: Dy3+, Tb3+ phosphors with excellent thermal stability and color tunability

In this paper, a variety of color-tunable LiLaSiO4: xDy3+, yTb3+ phosphors were manufactured by high temperature solid phase method. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Photoluminescence (PL) were used to characterize the phase, luminescence properties and thermal stability of the samples. In LiLaSiO4: Dy3+ phosphors, the best doping concentration is x = 0.03, corresponding to the pale yellow emission band. In LiLaSiO4: Dy3+, yTb3+ (y = 0–0.06) phosphors, energy transfer can be verified and the energy transfer mechanism are discussed in detail. In addition, by adjusting the concentration ratio of Dy3+/Tb3+ in LiLaSiO4 phosphors, the color tuning from pale yellow to green was realized. Finally, we also study its thermal stability, the activation energy (ΔE) is −0.1483 eV. Current research shows that Dy3+, Tb3+ co-doped LiLaSiO4 phosphors have wide application potential in fluorescent display devices.

Self-Reduction Mechanism and Luminescence Properties of Eu2+-Eu3+Doped Ca(PO3)2 Phosphor

A series of Ca(PO3)2 phosphors mono-doped with Eu3+ were successfully synthesized by the conventional high-temperature solid-phase method. Rietveld correction of the X-ray diffraction shows that Eu3+ ions occupy Ca2+ positions in the Ca(PO3)2 lattice and have no effect on the matrix structure. In this work, the self-reduction of Eu3+ was observed and verified by photoluminescence (PL), excitation spectroscopy (PLE) and X-ray photoelectron spectroscopy (XPS). Under excitation at 238 nm, Ca(PO3)2: Eu exhibits a broad blue Eu2+ emission band in addition to the usual orange-red emission of Eu3+. The fact that europium ions exist in divalent and trivalent forms was further confirmed, and the corresponding mechanism of the anomalous reduction of Eu3+ to Eu2+ is discussed. On this basis, the effect of Eu concentration on the structure and luminescence properties of Ca(PO3)2 phosphor was investigated in detail. The luminescence of the phosphor exhibited bright tunable emission in the blue region and the red region. These results indicate that the Ca(PO3)2: Eu phosphors have potential applications as a n-UV convertible phosphor for light-emitting diodes.

Synthesis of NaNi0.5Mn0.5O2 cathode materials for sodium-ion batteries via spray pyrolysis method

Because of the rich sodium reserves in nature, low cost, and high initial sodium content, O3-NaNi0.5Mn0.5O2 material stands out from other cathode materials. However, O3-NaNi0.5Mn0.5O2 shows poor kinetics and undergoes serious irreversible phase transitions, resulting in structural collapse and deteriorated cyclic performance. Herein, NaNi0.5Mn0.5O2 material with distinguished cyclic and rate performance was prepared via spray pyrolysis combined with a high-temperature solid-phase sintering method, which can deliver a specific capacity of 98.4 mAh g−1 at 1 C between 2.0 and 4.0 V. After 100 cycles, it shows outstanding capacity retention of 89.1 %. Moreover, it can recover 70.4 % of the capacity of 0.1 C even at a high rate of 10 C. This newly proposed synthesis method provides an alternative method to prepare superior electrode materials for sodium-ion batteries.

Synthesis, structure and thermal stability of iodine-contained sodalites Na8(AlSiO4)6Cl2-I (x = 0–2) for 129I immobilization

Sodalites are one of the potential candidate forms for the radioactive 129I immobilization. In this work, the synthesis, structure and thermal stability of iodine-contained sodalites Na8(AlSiO4)6Cl2-xIx (x = 0–2) were studied. The high temperature solid phase method combined with high pressure tableting and NaOH solution scrubbing was proposed to synthesize iodine-contained sodalites with single phase. The X-ray diffraction Rietveld analysis shows that, the crystal structure of Na8(AlSiO4)6Cl2-xIx varies as a function of the iodine content, x. The thermal stability of iodine-contained sodalites was studied by thermogravimetric analysis and high temperature annealing experiments. The iodine-contained sodalites exhibit good stability below 750 °C. A phase decomposition from the sodalite phase into the nepheline phase was observed for each composition at higher temperatures. The quantitative analysis of phase decomposition of Na8(AlSiO4)6Cl2-xIx annealed at 900 °C for 3 h further confirms the negative effects of iodine-doping on the thermal stability of samples.

Greatly enhanced deep-red luminescence performance of Ca2InSbO6:Mn4+ phosphor via multiple optimization strategies

Phosphors with high luminescence intensity, thermal stability, and spectral matching are important for indoor plant cultivation (IPC) light-emitting diodes (LEDs). Mn4+ ion-doped phosphors are considered potential deep-red emitters for plant growth LEDs. Herein, Ca2InSbO6:Mn4+ (CISO:Mn4+) phosphors were first synthesized via high-temperature solid-phase method. Their luminescence performance was greatly enhanced by using three kinds of strategies (charge compensator, solid solution, and rare earth ion co-doping). Furthermore, the optimization mechanisms were studied in depth on the basis of the principle of charge compensation and reduced quenching centers. Surprisingly, the internal quantum efficiency of the Ca1·9Y0·1InSb0·6Ta0·4O6:0.006Mn4+ phosphor was greatly enhanced to 71.4%, which was 42.75 times that of the CISO:0.006Mn4+ phosphor. Under 373 nm excitation, the Ca1·9Y0·1InSb0·6Ta0·4O6:0.006Mn4+ phosphor showed intense deep-red emission at 695 nm attributed to the 2Eg→4A2g transition of Mn4+ ions, which indicated a good match with far red phytochrome (Pfr, 84%). Finally, the fabricated IPC-LED displayed superior spectral matching, color purity (99.9%), and CIE chromaticity coordinates (0.692, 0.308). Thus, it has great potential as deep-red substitutes in the field of IPC. This work adopted a series of comprehensive strategies to optimize the luminescence performance of Mn4+-doped oxide phosphors and discussed the optimization mechanisms in depth, aiming to provide new ideas for the future optimization of phosphors.

Regulation of the Phase Composition on Zn1.4Al1.2Ge0.4O4: Cr3+ Phosphor Luminescence Color

We have proposed a type of Cr3+-doped Zn1.4Al1.2Ge0.4O4: Cr3+ phosphor by replacing ZnAl2O4: Cr3+ with germanium at different sintering temperatures in the high-temperature solid-phase method. Unlike the luminescence of common near-infrared ZnAl2O4 phosphors, Zn1.4Al1.2Ge0.4O4: Cr3+ phosphors have a more intense and persistent luminescence. At the same time, under the irradiation of 254 nm ultraviolet light, samples with different sintering temperatures show different luminescence colors. Phosphors exhibit long afterglow bluish white emission at sintering temperature below 1200 °C, and above 1200 °C (including 1200 °C), phosphors exhibit near-infrared long afterglow emission. This experiment systematically studies the effect of sintering temperature on Zn1.4Al1.2Ge0.4O4: Cr3+. The experimental results show that the abnormal blueish white emission of phosphors is related to the Zn2GeO4 formed during sintering. Zn2GeO4 is a self-luminous material with natural defects and shows a bluish white emission excited by ultraviolet rays. As the sintering temperature increases, the Zn2GeO4 phase in phosphors gradually disappears, Ge4+ ions enter the ZnAl2O4 lattice to replace Al3+ ions, and the emission color of Zn1.4Al1.2Ge0.4O4: Cr3+ phosphors changes from bluish white emission to near-infrared emission. Zn1.4Al1.2Ge0.4O4: Cr3+ phosphors showed different luminescence colors at different sintering temperatures, which enriched the luminescent properties of zinc aluminate-based phosphors.

A novel red phosphor Ca2 YNbO6 :Eu3+ for WLEDs.

Due to the advantages of good physicochemical properties, thermal stability, and optical properties, double perovskite compounds have received extensive attention. On this basis, a new type of red phosphor, Ca2 YNbO6 :xEu3+ , was synthesized using a high-temperature solid-phase method. Its phase purity, morphology, elemental composition, absorption spectrum, photoluminescence, thermal stability, and Commission Internationale de l'éclairage (CIE) chromaticity coordinates were thoroughly investigated. The results display that there is no impurity phase in the samples and the convergence factor Rwp = 14.2%; the microscopic particles are uniform and full, and the distribution of each element is uniform. The energy band gap ΔE is between 3.71 eV and 3.65 eV. The luminescence intensity is the best when the doped Eu3+ concentration x reaches 0.4, and emits 612 nm red light (5 D0 →7 F2 ) under 465 nm excitation, and the concentration quenching is attributed to a d-d interaction. The luminescence intensity at 425 K was still 75% of the room temperature luminescence intensity, which indicates that the thermal stability is extremely superior. The CIE chromaticity coordinates (0.6534, 0.3455) of the Ca2YNbO6:0.4Eu3+ phosphors are very close to National Television Standards Committee(0.670, 0.330), and the samples have low correlated colour temperature (2656 K) and high colour purity (99.90%). All findings suggest that Ca2 YNbO6 :Eu3+ can serve as a substitute for red phosphor in WLEDs.

Double Perovskite Ba2LaTaO6 for Ultrafast Fiber Lasers in Anomalous and Normal Net Dispersion Regime.

Double perovskites (DPs) have been attracting attention in an assortment of optoelectronic applications, for they hold advantages such as high quantum efficiency, long carrier migration distance and strong linear and nonlinear absorptions. As specific kinds of perovskites (PVKs), DPs are gifted with orthorhombic crystal structures which provide rich conversion combinations and broaden the space for research and application. However, few works have been reported about DPs in ultrafast photonics applications. In this article, a DP with chemical formula of Ba2LaTaO6 (BLT) was successfully synthesized by high-temperature solid phase method. The microstructures and morphologies were observed, and the linear and nonlinear absorption were characterized. By first using BLT as a novel saturable absorber in both normal and anomalous dispersion region fiber lasers, dual-wavelength soliton and dissipative soliton were successfully operated at C-band. This study affirms BLT’s nonlinear optical properties, lays the foundation for optical research on BLT, and meanwhile provides a meaningful reference for future development of pulsed lasers based on DPs.

Preparation and optical properties of CaYAl3O7:Eu2+, Dy3+ phosphors with blue long afterglow luminescence

In this paper, a new blue long afterglow luminescent material CaYAl3O7:Eu2+, Dy3+ was prepared by high-temperature solid-phase method. The physical phase analysis was carried out by X-ray diffraction; the elemental valence analysis was conducted by X-ray photoelectron spectroscopy; the luminescence properties of the samples were characterized by fluorescence spectrometer and UV absorption spectrometer; and the afterglow properties were measured by afterglow spectrometer. The results show that the doping of Eu2+ and Dy3+ did not change the physical phase of the crystals. In this long afterglow material, the introduction of Dy3+ as a trap center did not change the shape of the excitation and emission spectra of the samples, but the afterglow brightness can be significantly enhanced. The best afterglow performance was achieved when the doping concentration of Dy3+was 1%, with an afterglow time of 109 min for a brightness greater than 3.2 mcd/m2 discernible to the naked eye.

Preparation and luminescence properties of Ca2+-doped LaVO4:Dy3+ phosphors

LaVO4:Dy3+phosphors with and without Ca2+ doping (La1-x-y(DyxCay)VO4) were prepared by high temperature solid phase method, and their luminescence characteristics were studied. The luminescence performance of LaVO4 phosphor is the best when Dy3+ doping concentration is 0.05. Significant improvements in photoluminescence of LaVO4:Dy3+ phosphors were observed by Ca2+ doping. When the doping concentration of Ca2+ is 0.08, the luminescence performance of LaVO4 phosphor is the best. The Ca2+ ions incorporation increases the intensity of the Dy3+ ions luminescence. The underlying mechanisms of these results were calculated and investigated using first principles. The research shows that Ca2+ doping reduces the band gap value of LaVO4: Dy3+, resulting in the energy level splitting of Dy-d orbital, and the single atomic orbital shifts to higher energy direction after Ca2+ doping. First-principles calculations predict that calcium doping reduces the bandgap, resulting in matrix sensitization and an increase in luminescence intensity. Theoretical calculation results explain the improvement effect of Ca2+ doping on the luminescence properties of LaVO4:Dy3+ and reveal the mechanism.

Effect of High-Energy Ball Milling Mixing Process on Electrical Performance and Synthesis Temperature of LiFePO4/C Cathode Material

In this paper, high-energy ball milling method was used to prepare LiFePO4/C precursor and high temperature solid phase method to prepare LiFePO4/C cathode material. The influence of mixing process on the electrical performance and synthesis temperature of LiFePO4/C cathode material was studied by changing the ball milling time.The ball milling time selected in this paper is 0, 0.5, 1, 1.5, 2 h, and XRD, SEM and particle size analysis are used to characterize the properties of LiFePO4/C powder. The research results show that the LiFePO4/C powder obtained under the ball milling time of 1 h has the smallest particle size and uniform distribution. The XRD results also show that the LiFePO4/C phase obtained under this condition has good purity and crystallinity.The electrical performance of the LiFePO4/C material prepared after high-energy ball milling are tested. The results show that the first discharge specific capacity at 0.2 C rate is 163.3 m·Ah/g, which is 19.7% higher than that of the non-ball milled sample.The TG-DTA curve results show that the reaction temperature of the sample after high-energy ball milling is 454 °C, and the mass loss ends at about 570 °C. Compared with the sample without ball milling, the reaction temperature is reduced by 60 °C.The results of this study show that the preparation of precursor by high-energy ball milling can effectively improve the electrical performance of LiFePO4/C materials and reduce the material synthesis temperature.

Influence of Mn2+ doping on the emission spectrum of Sr2La8(SiO4)6O2:Eu(2+,3+) phosphor

A series of novel Sr1.9-xLa8(SiO4)6O2:0.1Eu(2+,3+), xMn2+ (0 ≤ x ≤ 0.10) phosphors were successfully prepared by high temperature solid-phase method. The series of samples belong to hexagonal system, and the space group is P63/m(1 7 6) or P-3. The emission spectrum range of Sr1.9-xLa8(SiO4)6O2:0.1Eu(2+,3+), xMn2+ are 500–750 nm. When x ≥ 0.03 mol, realizing the energy transfer of Eu3+ → Mn2+. The valence states of Eu and Mn in the phosphors were analyzed by XPS spectra. The emission light of Sr1.9-xLa8(SiO4)6O2:0.1Eu(2+,3+), xMn2+ phosphors is shifted from the yellow light region to the orange-red light region by controlling the Mn2+ ion doped.

Far-red-emitting LaSrRO4:Mn4+ (R = Al and Ga) phosphor: Synthesis and optical properties

LaSrRO4:Mn4+ (R = Al and Ga) are prepared by the high-temperature solid-phase method in air. Their luminescence properties, crystal structure, concentration dependent spectra, time-resolved spectra, fluorescence lifetime, and luminous mechanism are systematically researched, respectively. Mn4+ ion is the luminescence center of LaSrRO4:Mn4+ (R = Al and Ga). The excitation spectra of LaSrRO4:Mn4+ (R = Al and Ga) under monitored at 715 nm lie in the range 210 – 650 nm with two main excitation peaks at ∼360 nm and 520 nm. With the excitation at 360 and 520 nm, LaSrRO4:Mn4+ (R = Al and Ga) emit far-red light and have the emission spectra covering the region from 650 to 800 nm due to the 2Eg → 4A2g transition of Mn4+ ions. The ideal Mn4+ concentration in LaSrAlO4:Mn4+ and LaSrGaO4:Mn4+ are ∼ 0.4 mol% and 0.6 mol%, respectively. The spectral properties of samples verify the crystal field s via the Tanabe-Sugano energy level diagram of Mn4+ ion. LaSrRO4:Mn4+ (R = Al and Ga) have the emission spectra match with the absorption spectra of the plant photosensitive pigments red light and far-red light, which infers their promising application in plant growth light-emitting diode (LED) lamp