Effects of different iron sources on the performance of LiFePO_4/C composite cathode materials

Olivine LiFePO4/C composite cathode materials were synthesized by a solid state method in N2 ＋ 5vol% H2 atmosphere. The effects of different iron sources, including Fe（OH）3 and FeC2O4·2H2O, on the performance of as-synthesized cathode materials were investigated and the causes were also analyzed. The crystal structure, the morphology, and the electrochemical performance of the prepared samples were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, laser particle-size distribution measurement, and other electrochemical techniques. The results demonstrate that the LiFePO4/C materials obtained from Fe（OH）3 at 800℃ and FeC2O4·2H2O at 700℃ have the similar electrochemical performances. The initial discharge capacities of LiFePO4/C synthesized from Fe（OH）3 and FeC2O4·2H2O are 134.5 mAh.g^-1 and 137.4 mAh.g^-1 at the C/5 rate, respectively. How- ever, the tap density of the LiFePO4/C materials obtained from Fe（OH）3 are higher, which is significant for the improvement of the capacity of the battery.

Preparation of Luminescent Tb^3＋ Doped CaO Green Phosphor

CaCO3 was chosen as main raw material and Solid State method was used to prepare the sample. The precursor was directly sintered at 1100 ℃ with reducing atmosphere for 3 h to obtain new green CaO：Tb^3＋, Li^＋ Phosphors. The effects of the content of the doping ions Tb^3＋ on the luminescent properties have been studied. The structure, morphology and luminescent properties of the phosphors were characterized by XRD, SEM, UV and PL-PLE spectra respectively. The results showed that the CaO：Tb^3＋, Li^＋ was a single face-centered cubic crystals, the phosphor particle distributed uniformly. The phosphor has a strong absorptive capacity excited by 282 nm ultraviolet ray, and could emit the strong green light with the wavelength of 543 nm （^5D4→^7F5）. The CaO：Tb^3＋, Li^＋ is a new type of green fluorescent material.

The Effect of Replacement of Zn 2+ Cation with Ni 2+ Cation on the Structural Properties of Ba sub>2Zn sub>1–x Ni sub>xWO sub>6 Double Perovskite Oxides (X = 0, 0.25, 0.50, 0.75, 1)

The Ba2Zn1-xNixWO6 double perovskite oxides were synthesized using solid state reaction method. The effect of replacement of Zn2+ with Ni2+ cation on the structural properties was investigated by X-ray diffraction (XRD) at room temperature. From the X-ray diffraction and by means of standard Rietiveld method, the samples showed the same cubic crystal structure with (Fm-3m) space group and the crystallite size ranging from 71.91 nm to 148.71 nm. The unit cell volume was found to decrease as a result of the replacement, while there was no significant difference in the value of tolerance factor of the samples. This is may be due to the convergence of ionic radii of Ni2+ and Zn2+ cations. The Fourier Transform Infrared Spectroscopy (FTIR) was performed for the samples and the resultant characteristic absorption bands confirmed the double perovskite structure.

Synthesis of NiFe2O4 Nanowires with NiO Nanosheet as Precursor via a Topochemical Solid State Method

Large scale NiFe2O4 nanowires were synthesized with NiO nanosheets as precursor by means of the topochemical solid state method. The morphologies and magnetic properties of NiFe2O4 annealed at different temperatures were studied. An appropriate annealing temperature was requested to transfer NiO nanosheets and Feions into NiFe2O4 nanowires. In the beginning stage of synthesizing process, the shape ofNiO nanosheets remained unchanged at low temperatures. And then, NiO nanosheets split into nanowires from 400 ℃ to 600 ℃. At last they transformed into nanoparticles from 700 ℃ to 1000 ℃. Thus, the optimized annealing temperature was selected as 600 ℃ because the NiFe2O4 obtained at 600 ℃（N600） exhibited a maximum aspect ratio of 50 with a diameter of 20 nm and a length of 1 μm. Furthermore, N600 also displayed the largest magnetization value of 26.86 A·m^2/kg and the lowest coercivity（Hc） of 8914 A/m.

Synthesis and electrochemical performance of TiO_2-B as anode material

TiO2-B was synthesized by solid-state reaction. The structures, surface morphologies and electrochemical performances of TiO2-B were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM） and electrochemical measurement, respectively. The effects of calcining temperature, molar ratio of K2O to TiO2 and calcining time on the characteristics of TiO2-B were investigated. The results show that the calcining time exerts a significant influence on the electrochemical performances of TiO2-B. The TiO2-B is obtained with good crystal structure and suitable size by using K2Ti4O9, which is prepared at 950 ℃for 24 h under the condition of x（K2O）/x（TiO2）=1：3.5. The TiO2-B delivers all initial discharge capacity of 231.6 mA.h/g. And the rate caoacitv is 73.2 mA-h/g at 1 675 mA/g, which suggests that TiO2-B is a promising anode material for the lithium ion batteries.

Mass Production of Bi3NbO7/Bi2Zn(2/3)Nb(4/3)O7 Composites and Their Visible-light Photocatalytic Activity

Series Bi3NbO7/Bi2Zn（2/3）Nb（4/3）O7 （BN/BZN） composites were synthesized through a facile solid state reaction method. The products were characterized by X-ray diffraction（XRD）, field emission scanning electron microscopy（FE-SEM） and UV-vis diffuse reflectance spectroscopy（DRS）. When BN： BZN=0.1 mole ratio, the BN/BZN composite showed the best visible-light-driven photocatalytic performance, which decomposed nearly 100% of Rh B（10 ppm, p H=3-4） within 40 min. The results demonstrated that in-situ solid state synthesis of BN/BZN composites could be an efficient strategy to develop new photocatalyst for environmental remediation.

Preparation and Characterisation of Sr2CeO_4:Eu^(3+) Rare Earth Luminescent Material by High Temperature Mechano-Chemical Method

A novel, high-temperature, mechano-chemical（HTMC） method was developed to synthesise singlephase Sr_2CeO_4：Eu^（3＋）phosphor. Phosphors were characterised by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, and luminescence spectra. Compared with phosphors prepared by the traditional hightemperature solid state method and citric acid gel method, single-phase Sr_2CeO_4：Eu^（3＋）powders by using the HTMC method, with small average particle sizes of about 5 μm, a narrow size distribution range and uniform dispersion, were prepared at 800 ℃, and reached their maximum luminescent intensity at 900 ℃.Under ultraviolet excitation at 298 nm, the sample showed good luminescence with the strongest red light of 616 nm. However, Sr_2CeO_4：Eu^（3＋）was prepared at the higher temperature of 1100 ℃ by solid state method and citric acid gel method. The particle size was too large and uneven with phosphor agglomeration by high-temperature solid state method. The luminescent intensity reached a maximum for Sr_2CeO_4：Eu^（3＋）phosphor at a synthesis temperature of 1100 ℃ by using the high-temperature solid state method, and at 1200 ℃ by both citric acid gel and chemical precipitation methods. Furthermore, the advantages of the Sr_2CeO_4：Eu^（3＋）powder prepared by HTMC method were discussed compared with that prepared using traditional high-temperature solid state and citric acid gel methods.