Papers by Keyword: Solid-State Method

Abstract: In this study, LiTi₂(PO₄)₃ (LTP) was synthesized by the addition of lithium fluoride (LiF) of 0 %, 5 %, and 10 wt.%. A wet solid-state reaction method is applied by mixing Li₂CO₃, TiO_2, and NH₄H₂PO₄ into a ball mill, then calcined at 900^o C for 12 hr. XRD pattern of Fluoride-doped LTP is indexed and found in two phases. First is the Nasicon phase (LiTi₂(PO₄)₃) with rhombohedral structure, and second, the Olivine phase (LiTiPO5) with orthorhombic structure at the addition of 5 % and 10 wt. % of LiF. The higher LiF decreases the cell volume while the crystallite size, particle size, and material density increase. The morphology of the Fluoride-doped LTP is increasingly homogeneous and more rectangle-shape. LTP 2, adding 10 wt. % of LiF, has high ionic conductivity at 4.77 10^-4 S cm^-1 as a promising candidate material for solid-electrolyte of lithium-ion battery.

Abstract: Barium Titanate (BT) is one of the most intriguing ferroelectric materials widely exploited both for academic and technological utilization. The study aimed to investigate characteristics of BT ceramics Synthesized by co-precipitation (BT-C) and solid-state methods (BT-S) with variation of sintering temperatures. Here, the sintering temperatures are 900°C, 1000°C, 1100°C, and 1200°C for 4 h of each The characteristics are microstructure, morphology, and dielectric properties evaluated using X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), and Inductance-Capacitance-Resistance (LCR) meter, respectively. As results, the XRD patterns shows a pure perovskite single phase of BT was obtained by solid-state method at sintering temperature of 1000°C. While, the same result was obtained by co-precipitation at sintering temperature of 1100°C. The average crystallite size of BT-C and BT-S ceramics are in close values and getting larger with the higher sintering temperatures. Meanwhile, tetragonality of the BT-C tends to be larger as compared to the BT-S. The morphology results revealed big formed particles agglomeration (>5 μm) of the BT-C ceramics and the densities proportionally increased as the higher temperatures exhibited less porosity of ceramics. Meanwhile, the BT-S grains were visible and agglomerated in a much smaller size with the density values were different as the change of the sintering temperatures. The dielectric permittivity of the BT-C and BT-S ceramics were increased with higher sintering temperature. Further, the BT-C ceramics possessed higher permittivity than the BT-S due to high densities (less porosity) of ceramics. The highest permittivity of 1150 at 40 kHz was achieved by BT-C at 1200°C.

Abstract: The synthesis of LiFeSi_0.03P_0.97O₄/C (LFSP/C) composites have been done by solid state method. This study investigates the effects of carbon coating on the structure, microstructure and electrical conductivity of LFSP/C cathode materials. The carbon coating on Lithium Ferro Phosphate (LFP) plays a crucial role in determining its electrical conductivity. The variation of carbon content is 0wt.%; 6wt.%; 7wt.%; 8wt.% (LFP-0%, LFP-6%, LFP-7% and LFP-8%). The characterization was performed using X-Ray Diffraction (XRD), Scanning Electron Microscopy - Energy Dispersive X-ray (SEM-EDX), HighResolution-Transmission Electron Microscopy (HR-TEM) and LCR Meter tests. The XRD result have shown single-phase olivine (LiFePO₄) in all samples. The analysis microstructure using SEM have shown increasing carbon content can reduce agglomeration. The particles size of LFSP is 845.570 nm, and after coating carbon the particles size decreased up to 457.191 nm. The EDX results showed that the amount of atomic percentage for carbon tends to increase as the amount of carbon content increased. HR-TEM images indicates that the formation of carbon layer have formed, but not perfectly coat the LFP particle. The average carbon layer size is 78,31 nm with the size of LFSP particle is 352.82 nm. The LCR Meter result showed that LFP-7% had the largest electronic conductivity (2,275x10^-7 S/cm). The carbon coating led to significant enhancement in electronic conductivity from ~10^-9-10^-10 S/cm to ~10^-7 S/cm.

Abstract: Ba_0.95Ca_0.05Ti_0.85Zr_0.15O₃ (BCTZ) dielectric ceramics were fabricated by traditional solid-state method, using barium carbonate, calcium carbonate, titanium dioxide and zirconium dioxide as the starting materials. Rare earth dopants have a significant influence on the dielectric properties of BCTZ ceramics. The doping effects of Y and Ho with different content on the dielectric properties and structure were studied respectively. The results reveal that the effects of Y and Ho are similar, they perfer to occpy B site, and they move the dielectric peak to lower temperature, widen the peak and increase the insulation resistivity, thus improve the dielectric properties obviously. The effects were investigated by X-ray diffraction, scanning electron microscope, and dielectric property measurements. After rare earth elements-doping, the BCTZ ceramics satify the Y5V EIA specifications, mainly due to the change of structure. The BCTZ dielectric ceramics with high permittivity over 10,000, high insulation resistivity over 10¹² Ωcm, low dielectric loss less than 1%, can be applied in multilayer ceramic capacitors (MLCCs).

Abstract: Lanthanum magnesium hexaaluminate (LaMgAl11O19, LMA) has attracted much interest as its widely used in solid state lasers, TV phosphors and fluorescent lamps. In this paper, LaMgAl11O19 ceramic was pressureless sintered at 1650 °C for 10 h in air atmosphere using LaMgAl11O19 powders prepared by solid-state reaction at 1500 °C for 4 h. The result indicated that the synthesis temperature of LaMgAl11O19 powders was about 1500 °C. The LMA ceramic sample was dense and had a microstructure of platelet-like gains. The excitation spectrum shows two wide bands with the peaks at about 254 nm and 265 nm by monitoring the strongest 362 nm emission, and the emission spectra is consisted of a broad band emission with their peaks near 362 nm with a half-width about 5 nm exciting with 265 nm wavelength.

Abstract: In this experimental, solid state method is used to synthesize proportioned nano-ZnO and SiO₂ powders into Zn₂SiO₄ phosphor, and to achieve better control on grain size and grain shape than traditional powder. La is used to replace Mn; and to achieve better control on grain size and grain shape than traditional powder. With different sintering conditions, With different sintering conditions, the effect of the luminescent intensity due to sintering temperature and the concentration of activator would be discussed by the X-Ray Diffraction, SEM and TEM were utilized in the characterization of phase purity and microstructure of phosphor particles. Photoluminescence (PL) spectroscopy was utilized to characterize the optical properties. This use of phosphor materials is the application of the main light source, display components. Therefore, our study zinc silicate as the main principle of doping Mn, La of the characteristics of, expects to find the best glow.

Abstract: Spinel compounds Li4Ti5O12 were synthesized via solid state reaction in an Air atmosphere and electrochemical properties were investigated by means of X-ray diffraction, cyclic voltammetry, and charge–discharge tests. The results indicated that the compound was spinel structure, and the initial capacity could reach 162.28 mAh•g-1 and the cycling performance was good, implying the spinel structure of Li4Ti5O12 was more stable when the material was tested by charging-discharging. The Li+ could reversibly intercalate and deintercalate in the anode material. The material prepared by solid-state method showed a promising commercial application in lithium-ion batteries.

Abstract: Phase pure Li₄Ti₅O₁₂/C composite was synthesized by solid-state method using Li₂CO₃ and anatase TiO₂ as starting materials, and glucose, citric acid and oxalic acid as carbon sources, respectively. The effects of different carbon sources and various glucose amounts on the microstructure and electrochemical properties were systematically investigated. The as-prepared samples were characterized by means of XRD, SEM and particle size analysis. The electrochemical properties were investigated in terms of constant-current charge/discharge cycling tests. The results showed that the Li₄Ti₅O₁₂/C composite with 2wt% glucose exhibited the optimal electrochemical performance with a specific discharge capacity of 190.8mAh/g at 0.2C rate. The discharge capacity could still reach 151.0mAh/g after 80 cycles at 1C rate, exhibiting excellent cycling performance.

Abstract: Li₄Ti₅O₁₂ spinel-type anode materials were synthesized by high-energy ball milling and solid-state method using TiO₂ (Anatase) and Li₂CO₃ as starting materials. The powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), thermo-gravimetric (TG)/differential scanning calorimetric (DSC). The results showed that Li₄Ti₅O₁₂ in a single phase can be fabricated above 750 °C for 3h when the mixture powders were high-energy ball milled at 500r/m for 30min. The grain size was 0.3-0.5 m and particle size distribution was narrow.

Abstract: SiO₂, CaO and MgO was chosen as main raw material and Solid State method was used to prepare the samples. The precursor was directly sintered at 1000°Cfor 3h to obtain new green CaMgSi₂O₆:Eu³⁺,Li⁺Phosphors.The effects of the content of the doping ions Eu³⁺ on the luminescent properties have been studied. The structure, morphology and luminescent properties of the phosphors were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM),UV and PL-PLE spectra respectively.The results showed that the CaMgSi₂O₆:Eu³⁺,Li⁺ was base-centered monoclinic crystals, the phosphor particle distributed uniformly.The phosphor has a strong absorptive capacity excited by 248 nm ultraviolet ray, and could emit the strong red light with the wavelength of 590nm(⁵D₀→⁷F₁)and 615nm(⁵D₀→⁷F₂). The CaMgSi₂O₆:Eu³⁺,Li⁺ is a new type of red fluorescent material.