Synthesis and electrochemical characterization of nano-CeO2-coated nanostructure LiMn2O4 cathode materials for rechargeable lithium batteries

International Nuclear Information System (INIS)

Arumugam, D.; Kalaignan, G. Paruthimal

2010-01-01

LiMn 2 O 4 spinel cathode materials were coated with 0.5, 1.0, and 1.5 wt.% CeO 2 by a polymeric process, followed by calcination at 850 o C for 6 h in air. The surface-coated LiMn 2 O 4 cathode materials were physically characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron microscopy (XPS). XRD patterns of CeO 2 -coated LiMn 2 O 4 revealed that the coating did not affect the crystal structure or the Fd3m space group of the cathode materials compared to uncoated LiMn 2 O 4 . The surface morphology and particle agglomeration were investigated using SEM, TEM image showed a compact coating layer on the surface of the core materials that had average thickness of about 20 nm. The XPS data illustrated that the CeO 2 completely coated the surface of the LiMn 2 O 4 core cathode materials. The galvanostatic charge and discharge of the uncoated and CeO 2 -coated LiMn 2 O 4 cathode materials were measured in the potential range of 3.0-4.5 V (0.5 C rate) at 30 o C and 60 o C. Among them, the 1.0 wt.% of CeO 2 -coated spinel LiMn 2 O 4 cathode satisfies the structural stability, high reversible capacity and excellent electrochemical performances of rechargeable lithium batteries.

Electrochemical performance of high specific capacity of lithium-ion cell LiV3O8//LiMn2O4 with LiNO3 aqueous solution electrolyte

International Nuclear Information System (INIS)

Zhao Mingshu; Zheng Qingyang; Wang Fei; Dai Weimin; Song Xiaoping

2011-01-01

Research highlights: → In this paper, the electrochemical performance of aqueous rechargeable lithium battery with LiV 3 O 8 and LiMn 2 O 4 in saturated LiNO 3 electrolyte is studied. → The electrochemical performance tests show that the specific capacity of LiMn 2 O 4 using as the cathode of ARLB is similar to that of ordinary lithium-ion battery with organic electrolyte, which works much better than the formerly reported. → In addition, the cell systems exhibit good cycling performance. Therefore, it has great potential comparing with other batteries such as lead acid batteries and alkaline manganese batteries. - Abstract: The electrochemical performance of aqueous rechargeable lithium battery (ARLB) with LiV 3 O 8 and LiMn 2 O 4 in saturated LiNO 3 electrolyte is studied. The results indicate that these two electrode materials are stable in the aqueous solution and no hydrogen or oxygen produced, moreover, intercalation/de-intercalation of lithium ions occurred within the range of electrochemical stability of water. The electrochemical performance tests show that the specific capacity of LiMn 2 O 4 using as the cathode of ARLB is similar to that of ordinary lithium-ion battery with organic electrolyte, which works much better than the formerly reported. In addition, the cell systems exhibit good cycling performance. Therefore, it has great potential comparing with other batteries such as lead acid batteries and alkaline manganese batteries.

High rate performance of LiMn2O4 cathodes for lithium ion batteries synthesized by low temperature oxygen plasma assisted sol–gel process

International Nuclear Information System (INIS)

Chen, C.-L.; Chiu, K.-F.; Chen, Y.-R.; Chen, C.C.; Lin, H.C.; Chiang, H.Y.

2013-01-01

Nano-crystalline LiMn 2 O 4 thin films have been synthesized by the sol–gel process at low temperature (623 K). The low temperature prepared films are treated by a direct current pulsed oxygen plasma, and tested as cathodes for lithium batteries. The plasma treated films are able to sustain charge–discharge cycles under significant high current density of up to 5.4 A/g corresponding to 45 C for battery operation. The capacity ratio for discharging at 1.2 A/g and 0.024 A/g is over 65%, indicating low internal resistance, which meets the requirement of fast charge and discharge for electric vehicles. The stable high current density performances can be attributed to the formation of a dense surface morphology that is induced by the plasma irradiation. The formation of the surface morphology results in the more uniform current distribution on the film surface, which decreases the interface charge transfer resistances as measured by the electrochemical impedance spectra. - Highlights: • A low temperature process has been used to synthesize LiMn 2 O 4 thin films. • Plasma treatment can reduce the interface charge transfer resistances for LiMn 2 O 4 . • LiMn 2 O 4 cathodes treated by plasma treatment can deliver high rate capability

Checkerboard deposition of lithium manganese oxide spinel (LiMn2O4) by RF magnetron sputtering on a stainless steel in all-solid-state thin film battery

Science.gov (United States)

Hsueh, T. H.; Yu, Y. Q.; Jan, D. J.; Su, C. H.; Chang, S. M.

2018-03-01

All-solid-state thin film lithium batteries (TFLBs) are the most competitive low-power sources to be applied in various kinds of micro-electro-mechanical systems and have been draw a lot of attention in academic research. In this paper, the checkerboard deposition of all-solid-state TFLB was composed of thin film lithium metal anode, lithium phosphorus oxynitride (LiPON) solid electrolyte, and checkerboard deposition of lithium manganese oxide spinel (LiMn2O4) cathode. The LiPON and LiMn2O4 were deposited by a radio frequency magnetron sputtering system, and the lithium metal was deposited by a thermal evaporation coater. The electrochemical characterization of this lithium battery showed the first discharge capacity of 107.8 μAh and the capacity retention was achieved 95.5% after 150 charge-discharge cycles between 4.3V and 3V at a current density of 11 μA/cm2 (0.5C). Obviously, the checkerboard of thin film increased the charge exchange rate; also this lithium battery exhibited high C-rate performance, with better capacity retention of 82% at 220 μA/cm2 (10C).

Stress Induced Charge-Ordering Process in LiMn_2O_4

International Nuclear Information System (INIS)

Chen, Yan; Yu, Dunji; An, Ke

2016-01-01

In this letter we report the stress-induced Mn charge-ordering process in the LiMn_2O_4 spinel, evidenced by the lattice strain evolutions due to the Jahn–Teller effects. In situ neutron diffraction reveals the initial stage of this process at low stress, indicating the eg electron localization at the preferential Mn sites during the early phase transition as an underlying charge-ordering mechanism in the charge-frustrated LiMn_2O_4. The initial stage of this transition exhibits as a progressive lattice and charge evolution, without showing a first-order behavior.

Preparation of submicrocrystal LiMn2O4 used Mn3O4 as precursor and its electrochemical performance for lithium ion battery

International Nuclear Information System (INIS)

Liu, Bao-Sheng; Wang, Zhen-Bo; Zhang, Yin; Yu, Fu-Da; Xue, Yuan; Ke, Ke; Li, Fang-Fei

2015-01-01

Graphical abstract: Spinal LiMn 2 O 4 particles synthesized at 800 °C for 12 h has the best crystallinity with a submicron size and smallest cation disorder, resulting in a superior capacity retention ratio of 90.4% after 200 cycles at 1 °C at room temperature, which possesses an initial capacity of 106.8 mA h/g. - Highlights: • High purity spinel LiMn 2 O 4 was synthesized from industrial grade raw materials. • LiMn 2 O 4 prepared by optimal conditions has the smallest cation mixing. • Optimized LiMn 2 O 4 has the highest initial capacity with 112.9 mA h/g. • Capacity retention of optimized LiMn 2 O 4 is 90.4% after 200 cycles at 1 °C. - Abstract: Spinel LiMn 2 O 4 has been synthesized by solid state reaction with industrial grade Mn 3 O 4 and Li 2 CO 3 as precursors without purification, and its electrochemical performance for lithium ion battery has been investigated by CR2025 coin cell. The results of X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images show that the size of LiMn 2 O 4 particles grow up with increasing temperature of calcination, and the sample synthesized at 800 °C for 12 h has the best crystallinity with a submicron size. It can deliver initial capacity of 112.9 mA h/g with capacity retention ratio of 89.1% after 200 cycles at charge/discharge rate of 1 C. The results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) also show that it has the highest electrochemical activity and lowest charge transfer impedance

Study on lithium extraction from brines based on LiMn2O4/Li1-xMn2O4 by electrochemical method

International Nuclear Information System (INIS)

Zhao, Meng-Yao; Ji, Zhi-Yong; Zhang, Yong-Guang; Guo, Zhi-Yuan; Zhao, Ying-Ying; Liu, Jie; Yuan, Jun-Sheng

2017-01-01

Highlights: •A recovery system with LiMn 2 O 4 /Li 1-x Mn 2 O 4 as electrodes was used to extract lithium. •The influence sequence of coexisting ions on lithium extraction was Mg 2+ > Na + > Ca 2+ > K + . •The values of α Li-Na , α Li-Mg and α Li-Ca were more than 300, 70 and 110, respectively. •The specific energy consumption was between 18 and 19 W h·mol −1 . -- Abstract: Lithium rechargeable batteries have been used for lithium extraction in recent years. Here, we report on a highly selective lithium recovery system that consists of a LiMn 2 O 4 positive electrode, a Li 1-x Mn 2 O 4 negative electrode and a monovalent selective anion-exchange membrane. The effect of potential, temperature and coexisting ions on lithium extraction were investigated in this paper, and the lithium recovery system was applied to extract lithium from brine and concentrated seawater. The extraction capacity of Li + reached 34.31 mg· (1 g LiMn 2 O 4 ) −1 at 1.2 V. With higher reaction rate and lower energy consumption, 25 °C (room temperature) was considered as the appropriate temperature. The system still remained high selective for Li + even in the presence of impurity ions (K + , Na + , Mg 2+ , Ca 2+ ). With simulated brine and concentrated seawater as source solutions, the concentrations of Na + , Mg 2+ and Ca 2+ were reduced more than 300, 70 and 100 times, consuming 18–19 W h per mole of lithium recovered. And the electrodes still had high separation coefficients of Li + and Me n+ (Na + , Mg 2+ , Ca 2+ ) after five cycles although a slight drop was existing.

Sputtering graphite coating to improve the elevated-temperature cycling ability of the LiMn2O4 electrode.

Science.gov (United States)

Wang, Jiexi; Zhang, Qiaobao; Li, Xinhai; Wang, Zhixing; Guo, Huajun; Xu, Daguo; Zhang, Kaili

2014-08-14

To improve the cycle performance of LiMn2O4 at elevated temperature, a graphite layer is introduced to directly cover the surface of a commercial LiMn2O4-based electrode via room-temperature DC magnetron sputtering. The as-modified cathodes display improved capacity retention as compared to the bare LiMn2O4 cathode (BLMO) at 55 °C. When sputtering graphite for 30 min, the sample shows the best cycling performance at 55 °C, maintaining 96.2% capacity retention after 200 cycles. Reasons with respect to the graphite layer for improving the elevated-temperature performance of LiMn2O4 are systematically investigated via the methods of cyclic voltammetry, electrochemical impedance spectroscopy, X-ray photoelectron spectrometry, scanning and transmission electron microscopy, X-ray diffraction and inductively coupled plasma-atomic emission spectrometry. The results demonstrate that the graphite coated LiMn2O4 cathode has much less increased electrode polarization and electrochemical impedance than BLMO during the elevated-temperature cycling process. Furthermore, the graphite layer is able to alleviate the severe dissolution of manganese ions into the electrolyte and mitigate the morphological and structural degradation of LiMn2O4 during cycling. A model for the electrochemical kinetics process is also suggested for explaining the roles of the graphite layer in suppressing the Mn dissolution.

Characterization of surface-modified LiMn2O4 cathode materials with indium tin oxide (ITO) coatings and their electrochemical performance

International Nuclear Information System (INIS)

Kim, Chang-Sam; Kwon, Soon-Ho; Yoon, Jong-Won

2014-01-01

Graphical abstract: -- Highlights: • Indium tin oxide (ITO) is used to modify the surface of LiMn 2 O 4 by a sol–gel method. • The surface-modified layer was observed at a scale of several nanometers on LiMn 2 O 4 . • The ITO-coated LiMn 2 O 4 shows better capacity retention at 30 and 55 °C than pristine LiMn 2 O 4 . -- Abstract: Indium tin oxide (ITO) is used to modify the surface of LiMn 2 O 4 by a sol–gel method in an attempt to improve its electrochemical performance at elevated temperatures. The surface-modified LiMn 2 O 4 is characterized via XRD, FE-SEM, TEM, Auger electron spectroscopy (AES) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The surface layer modified by substitution with indium was observed at a scale of several nanometers near the surface on LiMn 2 O 4 . The concentration of ITO for electrochemical performance was varied from 0.3 wt% to 0.8 wt%. The 0.5 wt% ITO coated LiMn 2 O 4 showed the best electrochemical performance. This enhancement in electrochemical performance is mainly attributed to the effect of the surface layer modified through ITO, which could suppress Mn dissolution and reduce the charge transfer resistance at the solid electrolyte interface

Characterizations on the microstructures of LiMn2O4 prepared by a simple soft-chemical technique

International Nuclear Information System (INIS)

Wei Yingjin; Kim, Kwang Bum; Chen Gang; Park, Chul W.

2008-01-01

LiMn 2 O 4 powders were prepared by a simple soft-chemical technique at different temperatures. X-ray diffraction and thermogravimetric analysis suggested that the material prepared at 800 deg. C was stoichiometric LiMn 2 O 4 , whereas those prepared at 600 and 700 deg. C were Li[Mn 0.77 3+ Mn 1.23 4+ ]O 4.115 and Li[Mn 0.85 3+ Mn 1.15 4+ ]O 4.075 . Several typical XRD peaks of the compounds were investigated with an aim to elucidate (i) the Li immigration to the 16d octahedral sites, (ii) the partial tetragonal phase transition of the material and (iii) the mean coherent domain size and microstrain. SEM study showed that the particle size of the materials increased with heating temperature. The activation energy for the material particle growth was determined as 30.4 kJ mol -1

Synthesis, structure and electrochemistry of Ag-modified LiMn2O4 cathode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Zhou Wenjia; He Benlin; Li Hulin

2008-01-01

Spinel lithium manganese oxide was prepared by sol-gel method and a series of Ag/LiMn 2 O 4 composites with different Ag additive contents were prepared by thermal decomposition of AgNO 3 added to the pure LiMn 2 O 4 powders. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX) and various electrochemical measurement methods were used to examine the structural and electrochemical characteristics of the Ag/LiMn 2 O 4 composite powders. Phase analysis showed that Ag particles were dispersed on the surface of LiMn 2 O 4 instead of entering the spinel structure. According to the electrochemical tests results, it is clearly to see that Ag additives efficiently improved the cycling stability, reversibility and high-rate discharge capacity of pristine LiMn 2 O 4 by increasing the electrical conductivity between LiMn 2 O 4 particles, decreasing the polarization of cathode and reducing the dissolution of Mn. Meanwhile the influence of the Ag additive contents on the electrochemical properties of the Ag/LiMn 2 O 4 composites is also investigated in detail

Facile longitudinal unzipping of carbon nanotubes to graphene nanoribbons and their effects on LiMn2O4 cathodes in rechargeable lithium-ion batteries

International Nuclear Information System (INIS)

Ilango, P. Robert; Prasanna, K.; Subburaj, T.; Jo, Yong Nam; Lee, Chang Woo

2015-01-01

Highlights: • The graphene nanoribbons are successfully synthesized by chemical unzipping method. • The LiMn 2 O 4 is surface modified with graphene nanoribbons via ultrasonic-assisted wet-coating. • The electrochemical effects of graphene nanoribbons on LiMn 2 O 4 are studied. • The modified LiMn 2 O 4 shows the good electronic conductivity and improved capacity. - Abstract: A LiMn 2 O 4 cathode has been surface-modified with carbon nanotubes and graphene nanoribbons via an ultrasonic-assisted wet-coating method. The structural stability of the surface-modified LiMn 2 O 4 and the amorphous nature of the coated carbon materials are confirmed using X-ray diffraction (XRD). Field emission scanning electron microscopy (FE-SEM) reveals the strong and uniform distribution of graphene nanoribbons over the LiMn 2 O 4 in comparison to the carbon nanotubes-coated LiMn 2 O 4 . Furthermore, field emission transmission electron microscopy (FE-TEM) confirms the strong adhesion of a smooth, sheet-like graphene nanoribbons layer over the LiMn 2 O 4 surface, whereas the carbon nanotubes are observed to have weak and/or irregular contact with LiMn 2 O 4 . Electrochemical studies have been carried out by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and a galvanostatic cycler. The graphene nanoribbons-modified LiMn 2 O 4 cathode shows better electrochemical properties in terms of a suppressed charge transfer resistance, high current density, negative shift in polarization, longer calendar life, and high rate capabilities. In addition, the graphene nanoribbons-modified LiMn 2 O 4 delivered 90% of the retention capacity after 50 cycles at a rate of 1 C with the potential limits of 3.0–4.5 V vs. Li/Li + .

Growth behavior of LiMn2O4 particles formed by solid-state reactions in air and water vapor

International Nuclear Information System (INIS)

Kozawa, Takahiro; Yanagisawa, Kazumichi; Murakami, Takeshi; Naito, Makio

2016-01-01

Morphology control of particles formed during conventional solid-state reactions without any additives is a challenging task. Here, we propose a new strategy to control the morphology of LiMn 2 O 4 particles based on water vapor-induced growth of particles during solid-state reactions. We have investigated the synthesis and microstructural evolution of LiMn 2 O 4 particles in air and water vapor atmospheres as model reactions; LiMn 2 O 4 is used as a low-cost cathode material for lithium-ion batteries. By using spherical MnCO 3 precursor impregnated with LiOH, LiMn 2 O 4 spheres with a hollow structure were obtained in air, while angulated particles with micrometer sizes were formed in water vapor. The pore structure of the particles synthesized in water vapor was found to be affected at temperatures below 700 °C. We also show that the solid-state reaction in water vapor is a simple and valuable method for the large-scale production of particles, where the shape, size, and microstructure can be controlled. - Graphical abstract: This study has demonstrated a new strategy towards achieving morphology control without the use of additives during conventional solid-state reactions by exploiting water vapor-induced particle growth. - Highlights: • A new strategy to control the morphology of LiMn 2 O 4 particles is proposed. • Water vapor-induced particle growth is exploited in solid-state reactions. • The microstructural evolution of LiMn 2 O 4 particles is investigated. • The shape, size and microstructure can be controlled by solid-state reactions.

Nanoporous LiMn2O4 spinel prepared at low temperature as cathode material for aqueous supercapacitors

Science.gov (United States)

Wang, F. X.; Xiao, S. Y.; Gao, X. W.; Zhu, Y. S.; Zhang, H. P.; Wu, Y. P.; Holze, R.

2013-11-01

LiMn2O4 spinel was prepared by a hydrothermal method using α-MnO2 nanotubes as precursor at 180 °C, a temperature much lower than that in previously reported methods. It is nanoporous with a pore size of about 40-50 nm and a BET surface area of 9.76 m2 g-1. It exhibits a high specific capacitance of 189 F g-1 at 0.3 A g-1 as a cathode for an aqueous supercapacitor. Even at 12 A g-1, it still has a capacitance of 166 F g-1. After 1500 cycles, there is no evident capacity fading. The LiMn2O4 cathode can deliver an energy density of 31.9 Wh kg-1 at 3480 W kg-1 and even maintain 19.4 Wh kg-1 at about 5100 W kg-1 based on the mass of LiMn2O4.

Surface Modification of LiMn2O4 for Lithium Batteries by Nanostructured LiFePO4 Phosphate

Directory of Open Access Journals (Sweden)

B. Sadeghi

2012-01-01

Full Text Available LiMn2O4 spinel cathode materials have been successfully synthesized by solid-state reaction. Surface of these particles was modified by nanostructured LiFePO4 via sol gel dip coating method. Synthesized products were characterized by thermally analyzed thermogravimetric and differential thermal analysis (TG/DTA, X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and energy dispersive X-ray spectroscopy (EDX. The results of electrochemical tests showed that the charge/discharge capacities improved and charge retention of battery enhanced. This improved electrochemical performance is caused by LiFePO4 phosphate layer on surfaces of LiMn2O4 cathode particles.

Developments in the Material Fabrication and Performance of LiMn2O4 dCld Cathode Material

Science.gov (United States)

2016-06-13

manganese oxide spinel materials exhibit promising electrochemical performance and good thermodynamic and kinetic stability when used as a cathode in... oxide spinel (LiMn2O4) is a potential viable active cathode material for use in these versatile applications due to its low toxicity, good capacity...Developments in the Material Fabrication and Performance of LiMn2O4-dCld Cathode Material Paula C Latorre, Ashley L Ruth, and Terrill B Atwater

Co-hydrothermal synthesis of LiMn_2_3_/_2_4Mg_1_/_2_4PO_4·LiAlO_2/C nano-hybrid cathode material with enhanced electrochemical performance for lithium-ion batteries

International Nuclear Information System (INIS)

Zhang, Jun; Luo, Shaohua; Chang, Longjiao; Hao, Aimin; Wang, Zhiyuan; Liu, Yanguo; Xu, Qian; Wang, Qing; Zhang, Yahui

2017-01-01

Highlights: • A co-hydrothermal approach to synthesize LiMn_2_3_/_2_4Mg_1_/_2_4PO_4·LiAlO_2/C composite material in water/PEG system is present. • The Mn_1_-_xMg_xPO_4 precursor is prepared by precipitation reaction. • Co-modified with Mg"2"+ doping and LiAlO_2 compositing strategies play an important role in improving the electronic conductivity and facilitating the diffusion of lithium ion. • LiMn_2_3_/_2_4Mg_1_/_2_4PO_4·LiAlO_2/C composite material exhibits a high specific discharge capacity of 151.8 mAh/g at 0.05C. - Abstract: LiMn_2_3_/_2_4Mg_1_/_2_4PO_4·LiAlO_2/C is synthesized by a co-hydrothermal method in water/PEG system using Li_2CO_3, AAO and Mn_1_-_xMg_xPO_4 as raw material. The electronic structure and micromorphology of multi-component compound LiMn_1_-_xMg_xPO_4/C (x = 0, 1/24, 1/12, 1/6) and nano-hybrid LiMn_2_3_/_2_4Mg_1_/_2_4PO_4·LiAlO_2/C cathode materials are studied by first-principles calculation and experimental research including XRD, SEM, TEM. The calculated band gap of LiMn_2_3_/_2_4Mg_1_/_2_4PO_4/C is 2.296 eV, which is lower than other percentages Mg"2"+ doping samples. Electrochemical tests exhibit LiMn_2_3_/_2_4Mg_1_/_2_4PO_4/C has better cycling performance and rate capability than other contents Mg"2"+ doping samples with the discharge capacity of 143.5 mAh/g, 141.5 mAh/g, 139.2 mAh/g and 136.3 mAh/g at 0.05C, 0.1C, 0.5C and 1C in order. After compositing and preparation of LiMn_2_3_/_2_4Mg_1_/_2_4PO_4·LiAlO_2/C composite material by co-hydrothermal route, the initial discharge capacity reaches up to 151.8 mAh/g, which suggests that co-modified with Mg"2"+ doping and LiAlO_2 compositing material can improve the electronic conductivity of LiMnPO_4/C by facilitating the lithium ion diffusion rate in the interior of the materials.

Ab initio investigation of the thermodynamics of cation distribution and of the electronic and magnetic structures in the LiMn2O4 spinel

Science.gov (United States)

Santos-Carballal, David; Ngoepe, Phuti E.; de Leeuw, Nora H.

2018-02-01

The spinel-structured lithium manganese oxide (LiMn2O4 ) is a material currently used as cathode for secondary lithium-ion batteries, but whose properties are not yet fully understood. Here, we report a computational investigation of the inversion thermodynamics and electronic behavior of LiMn2O4 derived from spin-polarized density functional theory calculations with a Hubbard Hamiltonian and long-range dispersion corrections (DFT+U-D3). Based on the analysis of the configurational free energy, we have elucidated a partially inverse equilibrium cation distribution for the LiMn2O4 spinel. This equilibrium degree of inversion is rationalized in terms of the crystal field stabilization effects and the difference between the size of the cations. We compare the atomic charges with the oxidation numbers for each degree of inversion. We found segregation of the Mn charge once these ions occupy the tetrahedral and octahedral sites of the spinel. We have obtained the atomic projections of the electronic band structure and density of states, showing that the normal LiMn2O4 has half-metallic properties, while the fully inverse spinel is an insulator. This material is in the ferrimagnetic state for the inverse and partially inverse cation arrangement. The optimized lattice and oxygen parameters, as well as the equilibrium degree of inversion, are in agreement with the available experimental data. The partial equilibrium degree of inversion is important in the interpretation of the lithium ion migration and surface properties of the LiMn2O4 spinel.

Electrochemical properties of LiMn2O4 cathode material doped with an actinide

International Nuclear Information System (INIS)

Eftekhari, Ali; Moghaddam, Abdolmajid Bayandori; Solati-Hashjin, Mehran

2006-01-01

Metal substation as an efficient approach for improvement of battery performance of LiMn 2 O 4 was performed by an actinide dopant. Uranium as the last natural element and most common actinide was employed for this purpose. Cyclic voltammetric studies revealed that incorporation of uranium into LiMn 2 O 4 spinel significantly improves electrochemical performance. It also strengthens the spinel stability to exhibit better cycleability. Surprisingly, the capacity increases upon cycling of LiU 0.01 Mn 1.99 O 4 cathode. This inverse behavior is attributed to uniform distribution of dopant during insertion/extraction process. In other words, this is an electrochemical refinement of the nanostructure which is not detectable in microscale morphology, as rearrangement of dopant in nanoscale occurs and this is an unexceptional nanostructural ordering. In addition, uranium doping strengthens the Li diffusion, particularly at redox potentials

Structural study of the controlled hydrothermal synthesis of LiMn2O4 and LixMnyO2

DEFF Research Database (Denmark)

Christiansen, Troels Lindahl; Jensen, Kirsten Marie Ørnsbjerg; Shen, Yanbin

, a layered structure, which can also be described as a defective spinel structure. Here, we show that both LiMn2O4 and LixMnyO2 nanoparticles can be synthesized from a simple, low-temperature hydrothermal synthesis. By tuning a single synthesis parameter (Li-concentration) each of the 2 structures...

Neutron scattering study on cathode LiMn2O4 and solid electrolyte 5(Li2O)(P2O5)

International Nuclear Information System (INIS)

Kartini, E.; Putra, Teguh P.; Jahya, A. K.; Insani, A.; Adams, S.

2014-01-01

Neutron scattering is very important technique in order to investigate the energy storage materials such as lithium-ion battery. The unique advantages, neutron can see the light atoms such as Hydrogen, Lithium, and Oxygen, where those elements are negligible by other corresponding X-ray method. On the other hand, the energy storage materials, such as lithium ion battery is very important for the application in the electric vehicles, electronic devices or home appliances. The battery contains electrodes (anode and cathode), and the electrolyte materials. There are many challenging to improve the existing lithium ion battery materials, in order to increase their life time, cyclic ability and also its stability. One of the most scientific challenging is to investigate the crystal structure of both electrode and electrolyte, such as cathodes LiCoO 2 , LiMn 2 O 4 and LiFePO 4 , and solid electrolyte Li 3 PO 4 . Since all those battery materials contain Lithium ions and Oxygen, the used of neutron scattering techniques to study their structure and related properties are very important and indispensable. This article will review some works of investigating electrodes and electrolytes, LiMn 2 O 4 and 5(Li 2 O)(P 2 O 5 ), by using a high resolution powder diffraction (HRPD) at the multipurpose research reactor, RSG-Sywabessy of the National Nuclear Energy Agency (BATAN), Indonesia

Mixed bi-material electrodes based on LiMn2O4 and activated carbon for hybrid electrochemical energy storage devices

International Nuclear Information System (INIS)

Cericola, Dario; Novak, Petr; Wokaun, Alexander; Koetz, Ruediger

2011-01-01

Highlights: → Bi-material electrodes for electrochemical hybrid devices were characterized. → Bi-material electrodes have higher specific charge than capacitor electrodes. → Bi-material electrodes have better rate capability than battery electrodes. → Bi-material systems outperform batteries and capacitors in pulsed applications. - Abstract: The performance of mixed bi-material electrodes composed of the battery material, LiMn 2 O 4 , and the electrochemical capacitor material, activated carbon, for hybrid electrochemical energy storage devices is investigated by galvanostatic charge/discharge and pulsed discharge experiments. Both, a high and a low conductivity lithium-containing electrolyte are used. The specific charge of the bi-material electrode is the linear combination of the specific charges of LiMn 2 O 4 and activated carbon according to the electrode composition at low discharge rates. Thus, the specific charge of the bi-material electrode falls between the specific charge of the activated carbon electrode and the LiMn 2 O 4 battery electrode. The bi-material electrodes have better rate capability than the LiMn 2 O 4 battery electrode. For high current pulsed applications the bi-material electrodes typically outperform both the battery and the capacitor electrode.

Application of lithiated perfluorosulfonate ionomer binders to enhance high rate capability in LiMn2O4 cathodes for lithium ion batteries

International Nuclear Information System (INIS)

Chiu, Kuo-Feng; Su, Shih Hsuan; Leu, Hoang-Juh; Chen, Yi Shiang

2014-01-01

Lithiated perfluorosulfonate ionomer has been used as the binder for LiMn 2 O 4 cathodes. Casted membranes of the lithiated ionomer exhibit ionic conductivity of 1.4 × 10 −4 S/cm. Composite cathodes composed of LiMn 2 O 4 , carbon black and the ionomer binder have been fabricated. All components of the cathodes are well bound and dispersed as characterized by scanning electron microscope and energy dispersive spectroscope. The cathodes using the conventional poly-vinylidene fluoride binder have also been prepared for comparison. Under high rate (5 C-20 C) and high temperature (60 °C) operation, the LiMn 2 O 4 cathodes with the ionomer binder exhibit higher capacity and improved cycling stability. As indicated by the electrochemical impedance spectra, the ionomer binder forms ion-conducting interface layers on the LiMn 2 O 4 particles and results in lower interface resistance. It enables the cells utilizing the ionomer binder to achieve higher capacity and enhanced cycling stability even under harsh conditions

Electrochemical investigation of LiMn2O4 cathodes in gel electrolyte at various temperatures

International Nuclear Information System (INIS)

Hjelm, Anna-Karin; Eriksson, Tom; Lindbergh, Goeran

2002-01-01

A composite lithium battery electrode of LiMn 2 O 4 in combination with a gel electrolyte (1 M LiBF 4 /24 wt% PMMA/1:1 EC:DEC) has been investigated by galvanostatic cycling experiments and electrochemical impedance spectroscopy (EIS) at various temperatures, i.e. -3 -1 ), the solid phase transfer (∼45 kJ mol -1 ) and of the ionic bulk and effective conductance in the gel phase (∼34 kJ mol -1 ), respectively, were also determined. The kinetic results related to ambient temperature were compared to those obtained in the corresponding liquid electrolyte. The incorporated PMMA was found to reduce the ionic conductivity of the free electrolyte, and it was concluded that the presence of 24 wt% PMMA does not have a significant influence on the kinetic properties of LiMn 2 O 4

Synthesis of LiMn2O4 and LiCr0.2Mn1.8O4 powders by modified Pechini process

Directory of Open Access Journals (Sweden)

Alexandre Urbano

2009-03-01

Full Text Available LiMn2O4 and LiCr0.2Mn1.8O4 powders were synthesized by Pechini process, modified in order to reduce the number of steps and to work at temperatures below or equal to 400oC. Both phases crystallize in the same spinel structure with lattice constants of 8.21 and 8.22 Å respectively. Although the annealing temperature was low, the cristallinity is good and no residual amounts of organic material were detected.

Synthesis of lithium mangan dioxide (LiMn2O4) for lithium-ion battery cathode from various lithium sources

Science.gov (United States)

Priyono, S.; Ginting, N. R.; Humaidi, S.; Subhan, A.; Prihandoko, B.

2018-03-01

LiMn2O4 as a cathode material has been synthesized via solid state reaction. The synthesis has been done by varying lithium sources such as LiOH.H2O and Li2CO3 while MnO2 was used as Mn sources. All raw materials were mixed stoichiometrically to be the precursors of LiMn2O4. The precursors were sintered using high temperature furnace at 800 °C for 4 hours in atmospheric condition to form final product. The final products were sieved to separate the finer and smoother particles from the coarse ones. The products were characterized by X-Ray Diffractometer (XRD) to identify phases and crystal structure. The peak wave number was also determined using Fourier Transform Infra Red (FTIR) to find functional group. LiMn2O4 sheets were prepared by mixing active material with polyvinylidene fluoride (PVdF) and acetylene black (AB) in mass ratio of 85:10:5 wt.% in N,N-Dimethylacetamide (DMAc) solvents to form slurry. The slurry was then coated onto Al foil with thickness of about 0.15 mm and dried in an oven. LiMn2O4 sheet was cut into circular discs and arranged with separator, metallic lithium, and electrolyte in a coin cell. Automatic battery cycler was used to measure electrochemical performance and specific capacity of the cell. XRD analysis showed that sample synthesized with Li2CO3 has higher crystallinity and more pristine than sample synthesized with LiOH.H2O. FTIR analysis revealed that both of samples have identical functional group but sample with Li2CO3 source tend to degrade. Cyclic voltammetry data gave information that sample with LiOH.H2O source has better electrochemical performance. It showed double oxidation/reduction peaks more clearly but sample with Li2CO3 source has higher specific capacity (64.78 mAh/g) than sample with LiOH.H2O (50 mAh/g).

Molecular dynamics simulations of spinels: LiMn2O4 and Li4Mn5O12 at high temperatures

International Nuclear Information System (INIS)

Ledwaba, R S; Matshaba, M G; Ngoepe, P E

2015-01-01

Energy storage technologies are critical in addressing the global challenge of clean sustainable energy. Spinel lithium manganates have attracted attention due to their electrochemical properties and also as promising cathode materials for lithium-ion batteries. The current study focused on the effects of high temperatures on the materials, in order to understand the sustainability in cases where the battery heats up to high temperature and analysis of lithium diffusion aids in terms of intercalation host compatibility. It is also essential to understand the high temperature behaviour and lithium ion host capability of these materials in order to perform the armorphization and recrystalization of spinel nano-architectures. Molecular dynamics simulations carried out to predict high temperature behaviour of the spinel systems. The NVE ensemble was employed, in the range 300 - 3000K. The melting temperature, lithium-ion diffusion and structural behaviour were monitored in both supercell systems. LiMn 2 O 4 indicated a diffusion rate that increased rapidly above 1500K, just before melting (∼1700K) and reached its maximum diffusion at 2.756 × 10 -7 cm 2 s -1 before it decreased. Li 4 Mn 5 O 12 indicated an exponential increase above 700K reaching 8.303 × 10 −7 cm 2 s −1 at 2000K and allowing lithium intercalation even above its melting point of around 1300K. This indicated better structural stability of Li 4 Mn 5 O 12 and capability to host lithium ions at very high temperatures (up to 3000 K) compared to LiMn 2 O 4 . (paper)

Analyses of desorbed H2O with temperature programmed desorption technique in sol-gel derived HfO2 thin films

International Nuclear Information System (INIS)

Shimizu, H.; Nemoto, D.; Ikeda, M.; Nishide, T.

2009-01-01

Hafnium oxide (HfO 2 ) is a promising material for the gate insulator in highly miniaturized silicon (Si) ultra-large-scale-integration (ULSI) devices (32 nm and beyond). In the field chemistry, a sol-gel processing has been used to fabricate HfO 2 thin film with the advantages of low cost, relative simplicity, and easy control of the composition of the layers formed. Temperature-programmed desorption (TPD) has been used not only for analyzing adsorbed gases on the surfaces of bulk sol-gel-derived HfO 2 of sol-gel-derived HfO 2 thin film fired at 350, 450, 550 and 700 deg C in sol-gel derived HfO 2 films in air is investigated using TPD, and also the material characterization of HfO 2 thin films is evaluated by X-ray diffraction (XRD) method. The dielectric constant of the films was also estimated using the capacitance-voltage (C-V) method. TPD is essentially a method of analyzing desorped gases from samples heated by infra-red light as a function of temperature under vacuum conditions using a detector of quadruple mass spectroscopy (QMS). Sol-gel-derived HfO 2 films were fabricated on 76-mm-diameter Si(100) wafers as follows. Hafnia sol solutions were prepared by dissolving HfCl 4 in NH 4 OH solution, followed by the of HCOOH. (author)

Magnetic ordering in the spinel compound Li[Mn2?xLix]O4(x = 0,0.04)

NARCIS (Netherlands)

Gaddy, J.; Lamsal, J.; Petrovic, M.; Montfrooij, W.; Schmets, A.; Vojta, T.

2009-01-01

The two B-site ions Mn3+ and Mn4+ in the stoichiometric spinel structure LiMn2O4 form a complex, columnar ordered pattern below the charge-ordering transition at room temperature. On further cooling to below 66 K, the system develops long-range antiferromagnetic order. In contrast, whereas

Pengaruh Variasi Temperatur Hidrotermal Pada Sintesis Lithium Mangan Oksida (Limn2o4 Spinel Terhadap Efisiensi Adsorpsi Dan Desorpsi Ion Lithium Dari Lumpur Sidoarjo

Directory of Open Access Journals (Sweden)

Yusuf Kurniawan

2014-09-01

Full Text Available Perkembangan teknologi dalam bidang material menunjukkan perkembangan yang sangat pesat dalam beberapa tahun terakhir.Salah satu material yang sangat dibutuhkan dalam berbagai aplikasi adalah lithium. Lithium sendiri bisa didapatkan dari air laut brines dan geothermal fluid. Salah satunya adalah Lumpur Sidoarjo. Lithium Mangan Oksida Spinel digunakan sebagai material absorben karena murah, tidak beracun dan mudah didapatkan. Pada penelitian ini metode hidrotermal digunakan sebagai metode sintesis pada LiMn2O4 karena dapat dilakukan pada temperatur yang relatif rendah dan menghasilkan partikel yang lebih homogen. Metode hidrotermal dilakukan pada temperatur 160 oC, 180 oC dan 200 oC selama 24 jam. Pengujian XRD dilakukan untuk mengetahui struktur kristal. Pengujian SEM dilakukan untuk mengetahui morfologi material setelah proses hidrotermal. Pengujian BET dilakukan untuk mengetahui surface area. Setelah itu metode acid treatment dilakukan untuk proses adsorpsi dan desorpsi. Adsorpsi dilakukan dengan mencelupkan Lithium Mangan Oksida Spinel yang telah disintesis kedalam Lumpur Sidoarjo.Pengujian ICP dilakukan untuk mengetahui kandungan lithium yang terdapat pada Lumpur Sidoarjo sebelum dan sesudah adsorpsi untuk mengetahui jumlah lithium yang terserap.Pengujian desorpsi dilakukan dengan mencelupkan LiMn2O4 kedalam larutan HCL. Pada uji XRD menunjukkan bahwa LiMn2O4 berstruktur kristal cubic. Dari hasil uji SEM terlihat bahwa tidak banyak perbedaan morfologi pada ketiga variasi.Partikel cenderung membentuk aglomerasi. Pada hasil uji ICP menunjukkan bahwa LiMn2O4 dengan temperatur hidrotermal 160oC memiliki efisiensi adsorpsi paling tinggi dengan 6,775 ppm. Sementara untuk desorpsi yang paling tinggi adalah 200oC sebesar 0.081 ppm

Nature of the Electrochemical Properties of Sulphur Substituted LiMn2O4 Spinel Cathode Material Studied by Electrochemical Impedance Spectroscopy

Directory of Open Access Journals (Sweden)

Monika Bakierska

2016-08-01

Full Text Available In this work, nanostructured LiMn2O4 (LMO and LiMn2O3.99S0.01 (LMOS1 spinel cathode materials were comprehensively investigated in terms of electrochemical properties. For this purpose, electrochemical impedance spectroscopy (EIS measurements as a function of state of charge (SOC were conducted on a representative charge and discharge cycle. The changes in the electrochemical performance of the stoichiometric and sulphur-substituted lithium manganese oxide spinels were examined, and suggested explanations for the observed dependencies were given. A strong influence of sulphur introduction into the spinel structure on the chemical stability and electrochemical characteristic was observed. It was demonstrated that the significant improvement in coulombic efficiency and capacity retention of lithium cell with LMOS1 active material arises from a more stable solid electrolyte interphase (SEI layer. Based on EIS studies, the Li ion diffusion coefficients in the cathodes were estimated, and the influence of sulphur on Li+ diffusivity in the spinel structure was established. The obtained results support the assumption that sulphur substitution is an effective way to promote chemical stability and the electrochemical performance of LiMn2O4 cathode material.

In-situ synchrotron PXRD study of spinel LiMn2O4 formation

DEFF Research Database (Denmark)

Birgisson, Steinar; Jensen, Kirsten Marie Ørnsbjerg; Christiansen, Troels Lindahl

structural properties for the reaction being studied. Normally the reactions are started by heating and a constant temperature is kept throughout the experiment. In this study the hydrothermal reaction previously shown to produce spinel LiMn2O4 nanoparticles is studied in-situ to learn more about the phase......O4, depending on the initial concentration if Li-ions. An impurity phase, identified as Mn3O4, is also detected in different concentrations depending on reaction time and temperature. We have developed an experimental technique for in-situ measurements of solvothermal reactions under sub...... in the in-situ measurements it gives a unique opportunity to study reaction kinetics and thermodynamic quantities of the reactions. A temperature study of the reaction has been conducted to see how the formation rate and particle growth is affected by temperature while the precursor concentration is kept...

A simple, low-cost and eco-friendly approach to synthesize single-crystalline LiMn2O4 nanorods with high electrochemical performance for lithium-ion batteries

International Nuclear Information System (INIS)

Zhao, Hongyuan; Li, Fang; Liu, Xingquan; Xiong, Weiqiang; Chen, Bing; Shao, Huailing; Que, Dongyang; Zhang, Zheng; Wu, Yue

2015-01-01

The single-crystalline LiMn 2 O 4 nanorods were successfully synthesized by a simple, low-cost and eco-friendly approach in which the γ-MnOOH nanorods were prepared through a facile hydrothermal process, in which KMnO 4 was reduced by anhydrous alcohol (CH 3 CH 2 OH) without adding any template reagent or additional surfactant. The crystal structures and morphologies of synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The results showed that the γ-MnOOH nanorods had high crystallinity and well-shaped morphology with an average diameter of 200 nm and an average length of 12 μm. For the resulting LiMn 2 O 4 nanorods, the electrochemical properties were investigated by galvanostatic charge-discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). For the optimal LiMn 2 O 4 nanorods, the initial discharge capacity was 123.5 mAh g −1 and remained 110.2 mAh g −1 after 100 cycles at 1.0 C in the voltage range of 3.20∼4.35 V. Moreover, the optimal LiMn 2 O 4 nanorods can present superior rate performance, especially the capacity recovery performance as the charge-discharge rate restores to 0.1 C from 5.0 C. Such excellent electrochemical performance could make them to be the promising cathode material for high performance lithium-ion batteries

Electrochemistry and safety of Li 4Ti 5O 12 and graphite anodes paired with LiMn 2O 4 for hybrid electric vehicle Li-ion battery applications

Science.gov (United States)

Belharouak, Ilias; Koenig, Gary M.; Amine, K.

A promising anode material for hybrid electric vehicles (HEVs) is Li 4Ti 5O 12 (LTO). LTO intercalates lithium at a voltage of ∼1.5 V relative to lithium metal, and thus this material has a lower energy compared to a graphite anode for a given cathode material. However, LTO has promising safety and cycle life characteristics relative to graphite anodes. Herein, we describe electrochemical and safety characterizations of LTO and graphite anodes paired with LiMn 2O 4 cathodes in pouch cells. The LTO anode outperformed graphite with regards to capacity retention on extended cycling, pulsing impedance, and calendar life and was found to be more stable to thermal abuse from analysis of gases generated at elevated temperatures and calorimetric data. The safety, calendar life, and pulsing performance of LTO make it an attractive alternative to graphite for high power automotive applications, in particular when paired with LiMn 2O 4 cathode materials.

Probing localized strain in solution-derived YB a2C u3O7 -δ nanocomposite thin films

Science.gov (United States)

Guzman, Roger; Gazquez, Jaume; Mundet, Bernat; Coll, Mariona; Obradors, Xavier; Puig, Teresa

2017-07-01

Enhanced pinning due to nanoscale strain is unique to the high-Tc cuprates, where pairing may be modified with lattice distortion. Therefore a comprehensive understanding of the defect landscape is required for a broad range of applications. However, determining the type and distribution of defects and their associated strain constitutes a critical task, and for this aim, real-space techniques for atomic resolution characterization are necessary. Here, we use scanning transmission electron microscopy (STEM) to study the atomic structure of individual defects of solution-derived YB a2C u3O7 (YBCO) nanocomposites, where the inclusion of incoherent secondary phase nanoparticles within the YBCO matrix dramatically increases the density of Y1B a2C u4O8 (Y124) intergrowths, the commonest defect in YBCO thin films. The formation of the Y124 is found to trigger a concatenation of strain-derived interactions with other defects and the concomitant nucleation of intrinsic defects, which weave a web of randomly distributed nanostrained regions that profoundly transform the vortex-pinning landscape of the YBCO nanocomposite thin films.

In situ green synthesis of MnFe_2O_4/reduced graphene oxide nanocomposite and its usage for fabricating high-performance LiMn_1_/_3Fe_2_/_3PO_4/reduced graphene oxide/carbon cathode material for Li-ion batteries

International Nuclear Information System (INIS)

Wu, Kaipeng; Hu, Guorong; Peng, Zhongdong; Cao, Yanbing; Du, Ke

2016-01-01

Highlights: • MnFe_2O_4/rGO was prepared by an in situ green reduction-coprecipitation method. • LiMn_1_/_3Fe_2_/_3PO_4/rGO/C was synthesized by using MnFe_2O_4/rGO as precursor. • Both pyrolytic carbon and rGO could construct an interconnected conductive network. • LiMn_1_/_3Fe_2_/_3PO_4/rGO/C shows excellent electrochemical performance. - Abstract: MnFe_2O_4/reduced graphene oxide nanocomposite (MnFe_2O_4/rGO) has been synthesized via a green reduction-coprecipitation method for the first time, which involved in situ reduction of GO in presence of Fe"2"+ and the ensuing coprecipitation of Fe"3"+ and Mn"2"+ onto the surface of rGO. The resultant MnFe_2O_4/rGO was then employed as the precursor to fabricate LiMn_1_/_3Fe_2_/_3PO_4/reduced graphene oxide/carbon composite (LiMn_1_/_3Fe_2_/_3PO_4/rGO/C) cathode material for Li-ion batteries. The composite consists of homogeneous Mn-Fe distributed LiMn_1_/_3Fe_2_/_3PO_4 with its primary particles (∼200 nm) covered and connected by both pyrolytic carbon and rGO sheets, which could prevent the aggregation of the particles as well as construct an interconnected conductive network for rapid transmission of electrons during charging and discharging process. The fabricated LiMn_1_/_3Fe_2_/_3PO_4/rGO/C can deliver a discharge capacity of 94.8 mAh g"−"1 even at the high rate of 20C, and shows a capacity decay rate of only 6.25% after 900 long-term charge-discharge cycles. Moreover, the proposed synthesis strategy can also be applied to prepare other graphene-decorated multi-component cathode/anode materials for the Li-ion batteries.

Synthesis of Spherical Al-Doping LiMn2O4 via a High-Pressure Spray-Drying Method as Cathode Materials for Lithium-Ion Batteries

Science.gov (United States)

Zhang, Yannan; Zhang, Yingjie; Zhang, Mingyu; Xu, Mingli; Li, Xue; Yu, Xiaohua; Dong, Peng

2018-05-01

Uniform and spherical LiAl0.075Mn1.925O4 particles have been successfully synthesized by the high-pressure spray-drying method. The structures and electrochemical properties of the particles were characterized by various techniques. Benefiting from the sphere-like morphology and Al-doping, LiAl0.075Mn1.925O4 delivers a capacity retention of 81.6% after 1000 cycles at 2°C, while LiMn2O4 exhibits a capacity retention of only 32.2%. The rate capability and reversible cycling performance are also improved. Furthermore, this work significantly alleviates the dissolution of Mn in LiMn2O4 materials, and effectively improves the transfer rate of lithium ions at the electrode/electrolyte interface. The spherical LiAl0.075Mn1.925O4 prepared by a facile method shows great potential for practical application in low-cost and long-life lithium-ion batteries.

Experimental and ab initio investigations on textured Li–Mn–O spinel thin film cathodes

International Nuclear Information System (INIS)

Fischer, J.; Music, D.; Bergfeldt, T.; Ziebert, C.; Ulrich, S.; Seifert, H.J.

2014-01-01

This paper describes the tailored preparation of nearly identical lithium–manganese–oxide thin film cathodes with different global grain orientations. The thin films were synthesized by rf magnetron sputtering from a LiMn 2 O 4 -target in a pure argon plasma. Under appropriate processing conditions, thin films with a cubic spinel structure and a nearly similar density and surface topography but different grain orientation, i.e. (111)- and (440)-textured films, were achieved. The chemical composition was determined by inductively coupled plasma optical emission spectroscopy and carrier gas hot extraction. The constitution- and microstructure were evaluated by X-ray diffraction and Raman spectroscopy. The surface morphology and roughness were investigated by scanning electron and atomic force microscopy. The differently textured films represent an ideal model system for studying potential effects of grain orientation on the lithium ion diffusion and electrochemical behavior in LiMn 2 O 4 -based thin films. They are nearly identical in their chemical composition, atomic bonding behavior, surface-roughness, morphology and thickness. Our initial ab initio molecular dynamics data indicate that Li ion transport is faster in (111)-textured structure than in (440)-textured one. - Highlights: • Thin film model system of differently textured cubic Li–Mn–O spinels. • Investigation of the Li–Mn–O thin film mass density by X-ray reflectivity. • Ab initio molecular dynamics simulation on Li ion diffusion in LiMn 2 O 4

Molten salt-directed synthesis method for LiMn2O4 nanorods as a cathode material for a lithium-ion battery with superior cyclability

CSIR Research Space (South Africa)

Kebede, Mesfin A

2017-02-01

Full Text Available A molten salt synthesis technique has been used to prepare nanorods of Mn2O3 and single-crystal LiMn2O4 nanorods cathode material with superior capacity retention. The molten salt-directed synthesis involved the use of NaCl as the eutectic melt...

The use of a long chain ionic liquid in an LiMn2O4 based lithium ion cell

International Nuclear Information System (INIS)

Sutto, Thomas E.; Duncan, Teresa T.

2012-01-01

A long chain substituted imidazolium ionic liquid, 1,2-dimethyl-3-octylimidazolium bis(trifluoromethanesulfonyl)imide (MMOITFSI), is used as the electrolyte for reversible intercalation of Li into LiMn 2 O 4 . Ionic conductivity measurements indicate that in spite of the longer chain attached to the imidazolium ring, the conductivity for the pure liquid and with 0.5 M LiTFSI present, remains above 1 mS/cm. Cyclic voltammetry revealed high reversibility of Li + into LiMn 2 O 4 in this ionic liquid. Charge/discharge experiments indicated reversible capacity of 115 mAHr/g at a discharge rate of C/6 for 0.5 M Li in MMOITFSI. Higher discharge rates (C/3) resulted in lower capacities (below 100 mAHr/g), most likely due to the higher viscosity of the long chain ionic liquid. Improved discharge rates, of 111 mAHr/g at a higher discharge rate of C/3, were observed when 10 wt% of a short chain ionic liquid, 1,2-dimethyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide (MMPITFSI), was added to the MMOITFSI. For both the pure MMOITFSI and the ionic liquid blend of MMOITFSI with MMPITFSI, cycle lifetimes showed minimal degradation due to intercalation by the imidazolium cation into the graphite used to enhance the conductivity of the cathode material.

Enhancement of Electrochemical Performance of LiMn2O4 Spinel Cathode Material by Synergetic Substitution with Ni and S

Directory of Open Access Journals (Sweden)

Monika Bakierska

2016-05-01

Full Text Available Nickel and sulfur doped lithium manganese spinels with a nominal composition of LiMn2−xNixO4–ySy (0.1 ≤ x ≤ 0.5 and y = 0.01 were synthesized by a xerogel-type sol-gel method followed by subsequent calcinations at 300 and 650 °C in air. The samples were investigated in terms of physicochemical properties using X-ray powder diffraction (XRD, transmission electron microscopy (EDS-TEM, N2 adsorption-desorption measurements (N2-BET, differential scanning calorimetry (DSC, and electrical conductivity studies (EC. Electrochemical characteristics of Li/Li+/LiMn2−xNixO4–ySy cells were examined by galvanostatic charge/discharge tests (CELL TEST, electrochemical impedance spectroscopy (EIS, and cyclic voltammetry (CV. The XRD showed that for samples calcined at 650 °C containing 0.1 and 0.2 mole of Ni single phase materials of Fd-3m group symmetry and nanoparticles size of around 50 nm were obtained. The energy dispersive X-ray spectroscopy (EDS mapping confirmed homogenous distribution of nickel and sulfur in the obtained spinel materials. Moreover, it was revealed that the adverse phase transition at around room temperature typical for the stoichiometric spinel was successfully suppressed by Ni and S substitution. Electrochemical results indicated that slight substitution of nickel (x = 0.1 and sulfur (y = 0.01 in the LiMn2O4 enhances the electrochemical performance along with the rate capability and capacity retention.

Synthesis and electrochemical characteristics of spinel LiMn2O4 via a precipitation spray-drying process

International Nuclear Information System (INIS)

Wu, H.M.; Tu, J.P.; Yuan, Y.F.; Li, Y.; Zhao, X.B.; Cao, G.S.

2005-01-01

Spinel LiMn 2 O 4 has been successfully synthesized using a precipitation spray-drying process. After the precursor was annealed at 750 deg. C for 10 h, the synthesized material was well-crystallized spinel particle, and exhibited uniform particle size distribution. From cyclic voltammetry results, there is an anomalous redox peaks (3.75/3.26 V). In the charge/discharge potential (versus Li) ranging from 3.2 to 4.5 V, it delivered a high initial discharge capacity of 123 mAh/g at a discharge rate of 60 μA/cm 2 (1/4 C rate). At a high discharge rate of 2.4 mA/cm 2 (10 C rate), the obtainable reversible capacity was 79 mAh/g. The simple procedure of precipitation spray-drying process is time and energy saving, and thus is promising for commercial application

Deposition of Li{sub 4}Ti{sub 5}O{sub 12} and LiMn{sub 2}O{sub 4} films on the lithium-ion conductor of Li{sub 1.3}Al{sub 0.3}Ti{sub 1.7}(PO{sub 4}){sub 3} sintered pellet

Energy Technology Data Exchange (ETDEWEB)

Wu, Xian Ming, E-mail: xianmingwu@163.com [College of Chemistry and Chemical Engineering, Jishou University, Jishou Hunan 416000 (China); Xiangxi Minerals and New Materials Research and Service Center, Jishou Hunan 416000 (China); Chen, Shang [College of Chemistry and Chemical Engineering, Jishou University, Jishou Hunan 416000 (China); Xiangxi Minerals and New Materials Research and Service Center, Jishou Hunan 416000 (China); He, Ze Qiang; Chen, Shou Bin; Li, Run Xiu [College of Chemistry and Chemical Engineering, Jishou University, Jishou Hunan 416000 (China)

2015-08-31

LiMn{sub 2}O{sub 4} and Li{sub 4}Ti{sub 5}O{sub 12} films were deposited on the lithium-ion conductor of Li{sub 1.3}Al{sub 0.3}Ti{sub 1.7}(PO{sub 4}){sub 3} sintered pellet by spray technique. The effect of annealing temperature, annealing time, Li:Ti and Li:Mn molar ratio on the phase and crystallization of the films were investigated with X-ray diffraction. The LiMn{sub 2}O{sub 4}/Li{sub 1.3}Al{sub 0.3}Ti{sub 1.7}(PO{sub 4}){sub 3}/Li{sub 4}Ti{sub 5}O{sub 12} thin-film lithium-ion battery using Li{sub 1.3}Al{sub 0.3}Ti{sub 1.7}(PO{sub 4}){sub 3} sintered pellet as both electrolyte and substrate was also studied. The results show that the effect of annealing temperature, annealing time, Li:Ti and Li:Mn molar ratio has great effect on the phase and crystallization of Li{sub 4}Ti{sub 5}O{sub 12} and LiMn{sub 2}O{sub 4} films deposited on the Li{sub 1.3}Al{sub 0.3}Ti{sub 1.7}(PO{sub 4}){sub 3} sintered pellet. The optimal Li:Ti and Li:Mn molar ratio for the deposition of Li{sub 4}Ti{sub 5}O{sub 12} and LiMn{sub 2}O{sub 4} films on Li{sub 1.3}Al{sub 0.3}Ti{sub 1.7}(PO{sub 4}){sub 3} sintered pellet are 7.2:5 and 1.05:2, respectively. The optimal annealing temperature and time for the deposition of LiMn{sub 2}O{sub 4} film on Li{sub 1.3}Al{sub 0.3}Ti{sub 1.7}(PO{sub 4}){sub 3} sintered pellet are 650 °C and 10 min. While those for Li{sub 4}Ti{sub 5}O{sub 12} film are 700 °C and 10 min. The LiMn{sub 2}O{sub 4}/Li{sub 1.3}Al{sub 0.3}Ti{sub 1.7}(PO{sub 4}){sub 3}/Li{sub 4}Ti{sub 5}O{sub 12} thin-film battery offers a working voltage about 2.25 V and can be easily cycled. - Highlights: • LiMn{sub 2}O{sub 4} and Li{sub 4}Ti{sub 5}O{sub 12} films spray deposited on Li{sub 1.3}Al{sub 0.3}Ti{sub 1.7}(PO{sub 4}){sub 3} sintered pellet • Film crystal phase depends on the spray solution composition and annealing conditions. • Prepared thin-film lithium-ion battery employs sintered pellet as electrolyte and substrate. • LiMn{sub 2}O{sub 4}/Li{sub 1.3}Al{sub 0.3}Ti{sub 1

A new rechargeable lithium-ion battery with a xLi2MnO3.(1 - x) LiMn0.4Ni0.4Co0.2O2 cathode and a hard carbon anode

International Nuclear Information System (INIS)

Liu Jinlong; Wang Jie; Xia Yongyao

2011-01-01

Highlights: → A new type of battery with 0.4Li 2 MnO 3 0.6LiMn 0.4 Ni 0.4 Co 0.2 O 2 and hard carbon was proposed. → The irreversible capacity encountered at both electrodes, can be counterbalanced each other. → The battery delivers capacities of 105 mAh g -1 and specific energies of 315 Wh kg -1 . - Abstract: We reported a new type of rechargeable lithium-ion battery consisting of a structurally integrated 0.4Li 2 MnO 3 .0.6LiMnNi 0.4 Co 0.2 O 2 cathode and a hard carbon anode. The drawback of the high irreversible capacity loss of both electrodes, occurring at the first charge/discharge process, can be counterbalanced each other. The battery shows good reversibility with a sloping voltage from 1.5 V to 4.5 V and delivers a capacity of 105 mA h g -1 and a specific energy of 315 W h kg -1 based on the total weight of the both active electrode materials.

Chemical solution deposition of CaCu3Ti4O12 thin film

Indian Academy of Sciences (India)

Administrator

CaCu3Ti4O12; thin film; chemical solution deposition; dielectric properties. 1. Introduction. The CaCu3Ti4O12. (CCTO) compound has recently attracted considerable ... and Kelvin probe force microscopy (Chung et al 2004). Intrinsic .... SEM images of CCTO thin films as a function of sintering temperature. silicon based ...

Thin films of lithium manganese oxide spinel as cathode materials for secondary lithium batteries

International Nuclear Information System (INIS)

Shui, J.L.; Jiang, G.S.; Xie, S.; Chen, C.H.

2004-01-01

The miniaturization of rechargeable lithium-ion batteries requires high quality thin-film electrodes. Electrostatic spray deposition (ESD) technique was used to fabricate LiMn 2 O 4 thin-film electrodes with three different morphologies: sponge-like porous, fractal-like porous, and dense structures. X-ray diffraction (XRD) and scanning electron microscopy were used to analyze the structures of the electrodes. These electrodes were made into coin cells against metallic lithium for electrochemical characterization. Galvanostatic cycling of the cells revealed different rate capability for the cells with LiMn 2 O 4 electrodes of different morphologies. It is found that the cells with LiMn 2 O 4 electrodes of porous, especially the sponge-like porous, morphology better rate capability than those with dense LiMn 2 O 4 electrodes. Electrochemical impedance spectroscopy (EIS) study indicates that the large surface area of the porous electrodes should be attributed to the smaller interfacial resistance and better rate capability

Oxothiomolybdenum derivatives of the superlacunary crown heteropolyanion {P8W48}: structure of [K4{Mo4O4S4(H2O)3(OH)2}2(WO2)(P8W48O184)]30– and studies in solution.

Science.gov (United States)

Korenev, Vladimir S; Floquet, Sébastien; Marrot, Jérôme; Haouas, Mohamed; Mbomekallé, Israël-Martyr; Taulelle, Francis; Sokolov, Maxim N; Fedin, Vladimir P; Cadot, Emmanuel

2012-02-20

Reaction of the cyclic lacunary [H(7)P(8)W(48)O(184)](33-) anion (noted P(8)W(48)) with the [Mo(2)S(2)O(2)(H(2)O)(6)](2+) oxothiocation led to two compounds, namely, [K(4){Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2)(WO(2))(P(8)W(48)O(184))](30-) (denoted 1) and [{Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2)(P(8)W(48)O(184))](36-) (denoted 2), which were characterized in the solid state and solution. In the solid state, the structure of [K(4){Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2)(WO(2))(P(8)W(48)O(184))](30-) reveals the presence of two disordered {Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2+) "handles" connected on both sides of the P(8)W(48) ring. Such a disorder is consistent with the presence of two geometrical isomers where the relative disposition of the two {Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2+) handles are arranged in a perpendicular or parallel mode. Such an interpretation is fully supported by (31)P and (183)W NMR solution studies. The relative stability of both geometrical isomers appears to be dependent upon the nature of the internal alkali cations, i.e., Na(+) vs K(+), and increased lability of the two {Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2+) handles, compared to the oxo analogous, was clearly identified by significant broadening of the (31)P and (183)W NMR lines. Solution studies carried out by UV-vis spectroscopy showed that formation of the adduct [{Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2)(P(8)W(48)O(184))](36-) occurs in the 1.5-4.7 pH range and corresponds to a fast and quantitative condensation process. Furthermore, (31)P NMR titrations in solution reveal formation of the "monohandle" derivative [{Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(P(8)W(48)O(184))](38-) as an intermediate prior to formation of the "bishandle" derivatives. Furthermore, the electrochemical behavior of [{Mo(4)O(4)S(4)(H(2)O)(3)(OH)(2)}(2)(P(8)W(48)O(184))](36-) was studied in aqueous medium and compared with the parent anion P(8)W(48).

Synthesis and characterization of multilayered BaTiO3/NiFe2O4 thin films

Directory of Open Access Journals (Sweden)

Branimir Bajac

2013-03-01

Full Text Available Presented research was focused on the fabrication of multiferroic thin film structures, composed of ferrielectric barium titanate perovskite phase and magnetostrictive nickel ferrite spinel phase. The applicability of different, solution based, deposition techniques (film growth from solution, dip coating and spin coating for thefabrication of multilayered BaTiO3 /NiFe2O4 thin films was investigated. It was shown that only spin coating produces films of desired nanostructure, thickness and smooth and crackfree surfaces.

Synthesis and performance of LiMn0.7Fe0.3PO4 cathode material for lithium ion batteries

International Nuclear Information System (INIS)

Chang Xiaoyan; Wang Zhixing; Li Xinhai; Zhang Long; Guo Huajun; Peng Wenjie

2005-01-01

Pure and carbon-containing olivine LiMn 0.7 Fe 0.3 O 4 were synthesized at 600 deg. C by the method of solid-state reaction. Structure, surface morphology and charge/discharge performance of LiMn 0.7 Fe 0.3 O 4 were characterized by X-ray diffraction, scanning electron microscopy, and electrochemical measurement, respectively. The prepared materials with and without carbon both show the single olivine structure. The morphologies of primary particles are greatly affected by the addition of carbon. Large particles (500-1000 nm) and densely sintered blocks were observed in pure LiMn 0.7 Fe 0.3 PO 4 , which made the insertion and extraction of lithium ions difficult. Battery made from this sample can not charge and discharge effectively. The carbon-containing LiMn 0.7 Fe 0.3 PO 4 has a small particle size (100-200 nm) and a regular appearance. This material demonstrates high reversible capacity of about 120 mAh g -1 , perfect cycling performance, and excellent rate capability. It is obvious that the addition of carbon plays an important role in restricting the particle size of the material, which helps to prepare LiMn 0.7 Fe 0.3 PO 4 with excellent electrochemical performance. The electrochemical reaction resistance is much lower in the partly discharged state than in the fully charged or fully discharged state by the measurement of ac impedance for carbon-containing LiMn 0.7 Fe 0.3 PO 4 . It is indicated that the mixed-valence of Fe 3+ /Fe 2+ or Mn 3+ /Mn 2+ is beneficial to the transfer of electron which happens between the interface

Preparation of LiMn{sub 2}O{sub 4} cathode thin films for thin film lithium secondary batteries by a mist CVD process

Energy Technology Data Exchange (ETDEWEB)

Tadanaga, Kiyoharu, E-mail: tadanaga@chem.osakafu-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka, 599-8531 (Japan); Yamaguchi, Akihiro; Sakuda, Atsushi; Hayashi, Akitoshi; Tatsumisago, Masahiro [Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka, 599-8531 (Japan); Duran, Alicia; Aparacio, Mario [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas, Kelsen 5 (Campus de Cantoblanco), Madrid, 28049 (Spain)

2014-05-01

Highlights: • LiMn{sub 2}O{sub 4} thin films were prepared by using the mist CVD process. • An aqueous solution of lithium and manganese acetates is used for the precursor solution. • The cell with the LiMn{sub 2}O{sub 4} thin films exhibited a capacity of about 80 mAh/g. • The cell showed good cycling performance during 10 cycles. - Abstract: LiMn{sub 2}O{sub 4} cathode thin films for thin film lithium secondary batteries were prepared by using so-called the “mist CVD process”, employing an aqueous solution of lithium acetate and manganese acetate, as the source of Li and Mn, respectively. The aqueous solution of starting materials was ultrasonically atomized to form mist particles, and mists were transferred by nitrogen gas to silica glass substrate to form thin films. FE-SEM observation revealed that thin films obtained by this process were dense and smooth, and thin films with a thickness of about 750 nm were obtained. The electrochemical cell with the thin films obtained by sintering at 700 °C exhibited a capacity of about 80 mAh/g, and the cell showed good cycling performance during 10 cycles.

Magnetic signature of charge ordering in Li[Mn sub 1 sub . sub 9 sub 6 Li sub 0 sub . sub 0 sub 4]O sub 4 and Li sub 0 sub . sub 2 [Mn sub 1 sub . sub 9 sub 6 Li sub 0 sub . sub 0 sub 4]O sub 4

CERN Document Server

Verhoeven, V W J; Mulder, F M

2002-01-01

The stoichiometric compound LiMn sub 2 O sub 4 is known to show charge ordering with well-defined Mn sup 3 sup + and Mn sup 4 sup + sites just below room temperature (RT). Above RT the electrons are hopping rapidly between sites. For lithium-ion batteries the material Li[Mn sub 1 sub . sub 9 sub 6 Li sub 0 sub . sub 0 sub 4]O sub 4 is technologically relevant. Due to the small amount of Li on the Mn site, the low-T regular ordering of the Mn charge appears to be destroyed completely, as is evidenced by neutron diffraction in the magnetically ordered state. However, the charges are still fixed in an irregular fashion, as can also be deduced from sup 7 Li nuclear magnetic resonance measurements. In the lithium-extracted compound Li sub 0 sub . sub 2 [Mn sub 1 sub . sub 9 sub 6 Li sub 0 sub . sub 0 sub 4]O sub 4 , predominantly Mn sup 4 sup + is present. Neutron diffraction in the magnetically ordered state shows a well-defined antiferromagnetic ordering, with doubling of the unit cell in three directions. Clear...

High energy mechano-chemical milling: Convenient approach to synthesis of LiMn1.5Ni0.5O4 high voltage cathode for lithium ion batteries

International Nuclear Information System (INIS)

Datta, Moni Kanchan; Ramanathan, Madhumati; Jampani, Prashanth; Saha, Partha; Epur, Rigved; Kadakia, Karan; Chung, Sung Jae; Patel, Prasad; Gattu, Bharat; Manivannan, Ayyakkannu; Kumta, Prashant N.

2014-01-01

Graphical abstract: Nanostructured high voltage spinel phase of LiMn 1.5 Ni 0.5 O 4 (LMNO) of particle size ∼10–40 nm has been synthesized by a cost effective high energy mechanical milling (HEMM) approach followed by low temperature thermal treatments. High energy mechanical milling of lithium and manganese oxide precursors followed by moderate heat treatment results in the formation of single phase of LMNO, the high voltage spinel phase. The nanostructured LMNO has been studied as a high voltage cathode for lithium ion rechargeable batteries. Cyclic voltammetry as well as the differential capacity plots of nanostructured LMNO show the occurrence of two major reversible reactions occurring in the potential window of ∼2–3.6 V and ∼3.6–5.1 V with an associated specific capacity ∼105 mAh/g and ∼128 mAh/g, respectively. The nanostructured LMNO synthesized by the HEMM process followed by thermal treatments at ∼773 K, ∼873 K and ∼973 K shows a reversible capacity ∼120–110 mAh/g when cycled at a rate of ∼20 mA/g (∼C/6) in the potential window ∼3.6–5.1 V. Furthermore, the nanostructured HEMM derived LMNO shows a moderate rate capability with a capacity retention ∼87 mAh/g when cycled at ∼80 mA/g (∼C) rate. - Highlights: • Generation of LiMn 1.5 Ni 0.5 O 4 (LMNO) spinel by a cost effective HEMM process. • HEMM derived LMNO spinel phase shows a capacity of ∼128 mAh/g. • HEMM derived spinel exhibits a capacity retention of ∼87 mAh/g at ∼1C rate. • SEM analysis shows good structural integrity of the cycled electrode. • Charge transfer resistance increase during cycling causes capacity fade. - Abstract: The high voltage spinel form of LiMn 1.5 Ni 0.5 O 4 (LMNO) with a particle size ∼10–40 nm has been synthesized for the first time using high energy mechanical milling (HEMM) followed by low temperature thermal treatments using Li 2 O, MnO 2 and NiO as the starting precursors. The nanostructured LMNO cathode

Stable nickel-substituted spinel cathode material (LiMn1.9Ni0.1O4) for lithium-ion batteries obtained by using a low temperature aqueous reduction technique

CSIR Research Space (South Africa)

Kunjuzwa, Niki

2016-11-01

Full Text Available A nickel substituted spinel cathode material (LiMn1.9Ni0.1O4) with enhanced electrochemical performance was successfully synthesized by using a locally-sourced, low-cost manganese precursor, electrolytic manganese dioxide (EMD), and NiSO4·6H2O as a...

The effect of solution pH on the electrochemical performance of nanocrystalline metal ferrites MFe2O4 (M=Cu, Zn, and Ni) thin films

Science.gov (United States)

Elsayed, E. M.; Rashad, M. M.; Khalil, H. F. Y.; Ibrahim, I. A.; Hussein, M. R.; El-Sabbah, M. M. B.

2016-04-01

Nanocrystalline metal ferrite MFe2O4 (M=Cu, Zn, and Ni) thin films have been synthesized via electrodeposition-anodization process. Electrodeposited (M)Fe2 alloys were obtained from aqueous sulfate bath. The formed alloys were electrochemically oxidized (anodized) in aqueous (1 M KOH) solution, at room temperature, to the corresponding hydroxides. The parameters controlling the current efficiency of the electrodeposition of (M)Fe2 alloys such as the bath composition and the current density were studied and optimized. The anodized (M)Fe2 alloy films were annealed in air at 400 °C for 2 h. The results revealed the formation of three ferrite thin films were formed. The crystallite sizes of the produced films were in the range between 45 and 60 nm. The microstructure of the formed film was ferrite type dependent. The corrosion behavior of ferrite thin films in different pH solutions was investigated using open circuit potential (OCP) and potentiodynamic polarization measurements. The open circuit potential indicates that the initial potential E im of ZnFe2O4 thin films remained constant for a short time, then sharply increased in the less negative direction in acidic and alkaline medium compared with Ni and Cu ferrite films. The values of the corrosion current density I corr were higher for the ZnFe2O4 films at pH values of 1 and 12 compared with that of NiFe2O4 and CuFe2O4 which were higher only at pH value 1. The corrosion rate was very low for the three ferrite films when immersion in the neutral medium. The surface morphology recommended that Ni and Cu ferrite films were safely used in neutral and alkaline medium, whereas Zn ferrite film was only used in neutral atmospheres.

Thermodynamics of CoAl2O4-CoGa2O4 solid solutions

International Nuclear Information System (INIS)

Lilova, Kristina I.; Navrotsky, Alexandra; Melot, Brent C.; Seshadri, Ram

2010-01-01

CoAl 2 O 4 , CoGa 2 O 4 , and their solid solution Co(Ga z Al 1-z ) 2 O 4 have been studied using high temperature oxide melt solution calorimetry in molten 2PbO.B 2 O 3 at 973 K. There is an approximately linear correlation between lattice parameters, enthalpy of formation from oxides, and the Ga content. The experimental enthalpy of mixing is zero within experimental error. The cation distribution parameters are calculated using the O'Neill and Navrotsky thermodynamic model. The enthalpies of mixing calculated from these parameters are small and consistent with the calorimetric data. The entropies of mixing are calculated from site occupancies and compared to those for a random mixture of Ga and Al ions on octahedral site with all Co tetrahedral and for a completely random mixture of all cations on both sites. Despite a zero heat of mixing, the solid solution is not ideal in that activities do not obey Raoult's Law because of the more complex entropy of mixing. - Graphical abstract: Measured enthalpies of mixing of CoAl 2 O 4 -CoGa 2 O 4 solid solutions are close to zero but entropies of mixing reflect the complex cation distribution, so the system is not an ideal solution.

A Lithium-ion Battery Using Partially Lithiated Graphite Anode and Amphi-redox LiMn2O4 Cathode.

Science.gov (United States)

Jeon, Yuju; Noh, Hyun Kuk; Song, Hyun-Kon

2017-11-01

Delithiation followed by lithiation of Li + -occupied (n-type) tetrahedral sites of cubic LiMn 2 O 4 spinel (LMO) at ~4 [Formula: see text] (delivering ~100 mAh g LMO -1 ) has been used for energy storage by lithium ion batteries (LIBs). In this work, we utilized unoccupied (p-type) octahedral sites of LMO available for lithiation at ~3 [Formula: see text] (delivering additional ~100 mAh g LMO -1 ) that have never been used for LIBs in full-cell configuration. The whole capacity of amphi-redox LMO, including both oxidizable n-type and reducible p-type redox sites, at ~200 mAh g LMO -1 was realized by using the reactions both at 4 [Formula: see text] and 3 [Formula: see text]. Durable reversibility of the 3 V reaction was achieved by graphene-wrapping LMO nanoparticles (LMO@Gn). Prelithiated graphite (Li n C 6 , n < 1) was used as anodes to lithiate the unoccupied octahedral sites of LMO for the 3 V reaction.

Synthesis and Electrochemical Properties of Ni Doped Spinel LiNixMn2-xO4 (0 ≤ x ≤ 0.5) Cathode Materials for Li-Ion Battery

CSIR Research Space (South Africa)

Kebede, M

2013-11-01

Full Text Available Spherical pristine LiMn2O4 and Ni doped LiNixMn2-xO4 (x=0.1, 0.2, 0.3, 0.4, 0.5) cathode materials for lithium ion battery with high first cycle discharge capacity and excellent cycle performance were synthesized using the solution...

Synergetic Fe substitution and carbon connection in LiMn1−xFexPO4/C cathode materials for enhanced electrochemical performances

International Nuclear Information System (INIS)

Yan, Su-Yuan; Wang, Cheng-Yang; Gu, Rong-Min; Sun, Shuai; Li, Ming-Wei

2015-01-01

Highlights: • LiMn 0.6 Fe 0.4 PO 4 /C cathode material shows enhanced rate capability. • The Fe doped in the partial Mn sites could significantly facilitate the Li ions transfer. • The enhanced Li + ions diffusion contributes to the optimized rate capability of LiMn 0.6 Fe 0.4 PO 4 . • ACM carbonization forms well carbon coating and a 3D carbon network structure. - Abstract: To enhance the rate and cyclic performances of LiMnPO 4 cathode material for lithium-ion batteries, Mn is partially substituted with Fe, and LiMn 1−x Fe x PO 4 (x = 0.2, 0.3, 0.4, 0.5) solid solutions are synthesized and investigated. Amphiphilic carbonaceous material (ACM) forms well carbon coating and connects the LiMn 1−x Fe x PO 4 crystallites by a three-dimensional (3D) carbon network. The synergetic Fe substitution and carbon connection obviously improve the samples’ rate capacities and cyclic stability. The optimized LiMn 0.6 Fe 0.4 PO 4 /C sample delivers discharge capacities of 160 mA h g −1 at 0.05 C, 148 mA h g −1 at 1 C, and 115 mA h g −1 at 20 C. All samples have well capacity retention (>92%) after 50 charge/discharge cycles at 1 C. The enhanced electrochemical properties are mainly attributed to the improvement of Li ion and electron transport in the LiMn 1−x Fe x PO 4 /C samples, respectively mainly resulting from their modified crystal structures caused by Fe substitution and the 3D carbon coating/connection originating from ACM carbonization. LiMn 1−x Fe x PO 4 materials exhibit two discharge plateaus at ∼4.0 and ∼3.5 V (vs. Li + /Li), whose heights respectively reflect the redox potentials of Mn 3+ /Mn 2+ and Fe 3+ /Fe 2+ couples. The plateaus’ lengths correspond to the Mn/Fe ratio in LiMn 1−x Fe x PO 4 and are affected by the kinetic behavior of samples. Though the ∼4.0 V plateau shrinks with increasing discharge rate, the ∼3.5 V plateau may slightly elongate. Moreover, the Fe substituted in the partial Mn sites could significantly improve

Characterization of Carbon Composite LiMn1-xFexPO4 Cathodes

International Nuclear Information System (INIS)

Mishima, Y; Honda, S; Sadamura, H; Nakayama, N; Moriyoshi, C; Kuroiwa, Y

2011-01-01

The discharge capacities of 148 mAh/g (87 % theoretical value) at C/10 and 114mAh/g at 5C between 2.0 and 4.5 V at 25 deg. C were achieved for the carbon composite LiMn 0.8 Fe 0.2 PO 4 (C-LiMn 0.8 Fe 0.2 PO 4 ) cathode material of lithium-ion batteries (LIB), synthesized by a hydrothermal and annealing process. To improve the battery properties, we investigated the characteristics of C-LiMn 1-x Fe x PO 4 powders (x = 0.2 and 1) and the delithiated compound. While it was easier to form the homogeneous carbon layer on the surface of LiFePO 4 particles from the pyrolysis of sucrose, there was a tendency to form the particulate carbon on the LiMn 0.8 Fe 0.2 PO 4 particles. The lattice distortion of Mn 0.8 Fe 0.2 PO 4 was revealed by electron charge density study because of the Jahn-Teller active Mn 3+ ion associated with the phosphate ion. The surface and size of C- LiMn 0.8 Fe 0.2 PO 4 had to be modified because of these phenomena.

Chemical solution deposition of CaCu 3 Ti 4 O 12 thin film

Indian Academy of Sciences (India)

CaCu3Ti4O12 (CCTO) thin film was successfully deposited on boron doped silica substrate by chemical solution deposition and rapid thermal processing. The phase and microstructure of the deposited films were studied as a function of sintering temperature, employing X-ray diffractometry and scanning electron ...

n-Type Conductivity of Cu2O Thin Film Prepared in Basic Aqueous Solution Under Hydrothermal Conditions

Science.gov (United States)

Ursu, Daniel; Miclau, Nicolae; Miclau, Marinela

2018-03-01

We report for the first time in situ hydrothermal synthesis of n-type Cu2O thin film using strong alkaline solution. The use of copper foil as substrate and precursor material, low synthesis temperature and short reaction time represent the arguments of a new, simple, inexpensive and high field synthesis method for the preparation of n-type Cu2O thin film. The donor concentration of n-type Cu2O thin film obtained at 2 h of reaction time has increased two orders of magnitude than previous reported values. We have demonstrated n-type conduction in Cu2O thin film prepared in strong alkaline solution, in the contradiction with the previous works. Based on experimental results, the synthesis mechanism and the origin of n-type photo-responsive behavior of Cu2O thin film were discussed. We have proposed that the unexpected n-type character could be explained by H doping of Cu2O thin film in during of the hydrothermal synthesis that caused the p-to-n conductivity-type conversion. Also, this work raises new questions about the origin of n-type conduction in Cu2O thin film, the influence of the synthesis method on the nature of the intrinsic defects and the electrical conduction behavior.

Thermal Measurement during Electrolysis of Pd-Ni Thin-film -Cathodes in Li2SO4/H2O Solution

Science.gov (United States)

Castano, C. H.; Lipson, A. G.; S-O, Kim; Miley, G. H.

2002-03-01

Using LENR - open type calorimeters, measurements of excess heat production were carried out during electrolysis in Li_2SO_4/H_2O solution with a Pt-anode and Pd-Ni thin film cathodes (2000-8000 Åthick) sputtered on the different dielectric substrates. In order to accurately evaluate actual performance during electrolysis runs in the open-type calorimeter used, considering effects of heat convection, bubbling and possible H_2+O2 recombination, smooth Pt sheets were used as cathodes. Pt provides a reference since it does not produce excess heat in the light water electrolyte. To increase the accuracy of measurements the water dissociation potential was determined for each cathode taking into account its individual over-voltage value. It is found that this design for the Pd-Ni cathodes resulted in the excess heat production of ~ 20-25 % of input power, equivalent to ~300 mW. In cases of the Pd/Ni- film fracture (or detachment from substrate) no excess heat was detected, providing an added reference point. These experiments plus use of optimized films will be presented.

Modification of low temperature deposited LiMn2O4 thin film cathodes by oxygen plasma irradiation

International Nuclear Information System (INIS)

Chen, Chen Chung; Chiu, Kuo-Feng; Lin, Kun Ming; Lin, Hsin Chih

2009-01-01

Lithium manganese oxides have been deposited by radio frequency magnetron sputter deposition with relatively lower annealing temperatures and then post-treated with a radio frequency (rf) driven oxygen plasma. Following oxygen plasma irradiation, the film properties were modified, and the performance of the thin film cathode has been enhanced. The electrochemical properties of the treated thin-film cathodes were characterized and compared. The results showed that the samples with moderate plasma treatment also maintained good cyclic properties as cycled at a wide range potential window of 2.0 V-4.5 V. Its electrochemical properties were significantly improved by this process, even though the films were prepared under low annealing temperature.

Effect of solution composition on anatase to rutile transformation of sprayed TiO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Juma, Albert Owino, E-mail: albert.juma@ttu.ee [Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, EE-19086 Tallinn (Estonia); Acik, Ilona Oja [Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, EE-19086 Tallinn (Estonia); Mikli, Valdek [Chair of Semiconductor Materials Technology, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, EE-19086 Tallinn (Estonia); Mere, Arvo; Krunks, Malle [Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, EE-19086 Tallinn (Estonia)

2015-11-02

Acetylacetone is used as a chelating agent for titanium(IV) isopropoxide to inhibit hydrolysis and stabilize the precursor solution. The effect of the molar ratio between titanium(IV) isopropoxide and acetylacetone of 1:1, 1:2, 1:3 and 1:4 in the precursor solution on the morphological, structural and optical properties of TiO{sub 2} thin film was investigated. These properties were studied using Fourier transformed infrared spectroscopy, scanning electron microscopy, Raman spectroscopy, X-ray diffraction and UV–vis spectroscopy as a function of the molar ratios for the as-deposited thin films and films annealed at temperatures of 700, 800 and 950 °C. Mixed anatase and rutile phases were detected after annealing at 800 °C for 1:1 and 1:2 molar ratios and at 700 °C for 1:3 and 1:4 molar ratios. The optical band gap decreased from 3.45 to 3.02 eV with an increase in the annealing temperature in agreement with corresponding structural changes. - Highlights: • The grain sizes of TiO{sub 2} thin films could be varied over the range of 20 to 210 nm. • TTIP and AcacH ratio affects the transformation process from anatase to rutile. • TiO{sub 2} bandgap decreased from 3.45 to 3.02 eV with an increase in annealing temperature.

A feasibility study on SnO2/NiFe2O4 nanocomposites as anodes for Li ion batteries

International Nuclear Information System (INIS)

Balaji, S.; Vasuki, R.; Mutharasu, D.

2013-01-01

Highlights: ► The morphological analysis performed has shown the existence of nanocomposite. ► Sp. capacity after 50 cycles of pure NiFe 2 O 4 , 5 and 10 wt.% SnO 2 are 450, 750 and 780 mA h/g. ► The results are higher than the theoretical capacity of graphite (374 mA h/g). ► The capacity retention is also found to increase with SnO 2 addition in the NiFe 2 O 4 . ► Charge and discharge capacities of LiMn 2 O 4 vs. 10 wt.% SnO 2 /NiFe 2 O 4 are 232 and 138 mA h/g. -- Abstract: The SnO 2 /NiFe 2 O 4 nanocomposite samples with varying concentration of SnO 2 such as 5 wt.% and 10 wt.% were synthesized via urea assisted combustion synthesis. The kinetics of the combustion reactions were studied using thermo gravimetry analysis and from which the compound formation temperature of all the samples were observed to be below 400 °C. From the morphological analysis the grain size of NiFe 2 O 4 , 5 wt.% SnO 2 /NiFe 2 O 4 and 10 wt.% SnO 2 /NiFe 2 O 4 samples were observed to be around 1.7, 2.3 and 3.5 μm. The chrono potentiometry analyses of the samples were performed against lithium metal electrode. The capacity retention was found to be higher for composite with 10 wt.% SnO 2 . The discharge capacity of 10 wt.% SnO 2 sample with respect to Li metal and LiMn 2 O 4 electrode was observed to be around 980 mA h/g and 138 mA h/g respectively

Preparation of Li4Ti5O12 electrode thin films by a mist CVD process with aqueous precursor solution

Directory of Open Access Journals (Sweden)

Kiyoharu Tadanaga

2015-03-01

Full Text Available Spinel Li4Ti5O12 thin films were prepared by a mist CVD process, using an aqueous solution of lithium nitrate and a water-soluble titanium lactate complex as the source of Li and Ti, respectively. In this process, mist particles ultrasonically atomized from a source aqueous solution were transferred by nitrogen gas to a heating substrate to prepare thin films. Scanning electron microscopy observation showed that thin films obtained by this process were dense and smooth, and thin films with a thickness of about 500 nm were obtained. In the X-ray diffraction analysis, formation of Li4Ti5O12 spinel phase was confirmed in the obtained thin film sintered at 700 °C for 4 h. The cell with the thin films as an electrode exhibited a capacity of about 110 mAh g−1, and the cell showed good cycling performance during 10 cycles.

Solid solutions in the system Nd2(SeO4)3 - Sm2(SeO4)3 - H2O

International Nuclear Information System (INIS)

Serebrennikov, V.V.; Tsybukova, T.N.; Velikov, A.A.

1984-01-01

Using the method of isothermal solubility at 25 deg C the system Nd 2 (SeO 4 ) 3 -Sm 2 (SeO 4 ) 3 -H 2 O has been studied. Roentgenographic recording of solid ''residues'' is realized. For solid solutions energies of interchange and formation heats are calculated. Formation heats of solid solutions on the basis of samarium selenates are also found experimentally

Electrodeposited ZnIn{sub 2}S{sub 4} onto TiO{sub 2} thin films for semiconductor-sensitized photocatalytic and photoelectrochemical applications

Energy Technology Data Exchange (ETDEWEB)

Assaker, Ibtissem Ben, E-mail: ibtissem.ben-assaker@laposte.net [Laboratoire Photovoltaïque, Centre de Recherches et des Technologies de l’Energie Technopole borj cedria, Bp 95, Hammamm lif 2050 (Tunisia); Gannouni, Mounir; Naceur, Jamila Ben [Laboratoire Photovoltaïque, Centre de Recherches et des Technologies de l’Energie Technopole borj cedria, Bp 95, Hammamm lif 2050 (Tunisia); Almessiere, Munirah Abdullah; Al-Otaibi, Amal Lafy; Ghrib, Taher [Laboratory of Physical Alloys (LPA), College of Science, University of Dammam (Saudi Arabia); Shen, Shouwen [Advanced Analysis Unit, Technical Service Division Research & Development Center Saudi Aramco, Dhahran (Saudi Arabia); Chtourou, Radhouane [Laboratoire Photovoltaïque, Centre de Recherches et des Technologies de l’Energie Technopole borj cedria, Bp 95, Hammamm lif 2050 (Tunisia)

2015-10-01

Graphical abstract: - Highlights: • ZnIn{sub 2}S{sub 4} thin films was grown using electrodeposition route onto TiO{sub 2}/ITO coated glass substrate. • Study of the heterostructure ZnIn{sub 2}S{sub 4}/TiO{sub 2} thin films. • Photocatalytic activity of ZnIn{sub 2}S{sub 4}/TiO{sub 2} heterostructure under visible light irradiation. • High performance of Photoelectrochemical properties in the presence of the junction ZnIn{sub 2}S{sub 4}/TiO{sub 2}. - Abstract: In this study, ZnIn{sub 2}S{sub 4}/TiO{sub 2} heterostructure was successfully synthesized on ITO-coated glass substrates via a facile two-step process from aqueous solution. First, TiO{sub 2} thin film was prepared by sol–gel and deposited onto ITO coated glass substrate by spin-coating method. Then the zinc indium sulfide semiconductor was fabricated via electrodeposition technique onto TiO{sub 2}/ITO coated glass electrode. The X-ray diffraction patterns confirm that the heterostructure is mixed of both Anatase TiO{sub 2} and Rhombohedric ZnIn{sub 2}S{sub 4}. The scanning electron microscopy (SEM) images show that the morphology change with the deposition of ZnIn{sub 2}S{sub 4} over TiO{sub 2} thin film and a total coverage of the electrode surface was obtained. Optical absorption spectroscopy study of ZnIn{sub 2}S{sub 4}/TiO{sub 2} heterostructure exhibits a remarkable red-shift compared to the TiO{sub 2} and ZnIn{sub 2}S{sub 4} achieve the best efficiency of visible light absorption. Therefore, it is expected to apply to visible-light photocatalysis and solar cells. To investigate the effect of the heterojunction on the photocatalytic activity of ZnIn{sub 2}S{sub 4}/TiO{sub 2} thin films, photodegradation of methylene blue in the presence of ZnIn{sub 2}S{sub 4} was performed. ZnIn{sub 2}S{sub 4}/TiO{sub 2} heterostructure exhibited strong photocatalytic activity, and the degradation of methylene blue eached 91% after irradiation only for 4 h. Also, the study of the photocurrent density produced

Mixed-carbon-coated LiMn_0_._4Fe_0_._6PO_4 nanopowders with excellent high rate and low temperature performances for lithium-ion batteries

International Nuclear Information System (INIS)

Zou, Bang-Kun; Wang, He-Yang; Qiang, Zi-Yue; Shao, Yu; Sun, Xin; Wen, Zhao-Yin; Chen, Chun-Hua

2016-01-01

Graphical abstract: Ascorbic acid acts as both an antioxidant and a surfactant to form organic groups (first carbon source) on the surface of as-solvothermal products, in which the −OH (or H_2O) groups of glucose (second carbon source) are closely bonded to the surface to form a uniform adsorption layer. Uniform mixed-carbon-coated LiMn_0_._4Fe_0_._6PO_4 nanopowders are formed after calcination, which demonstrate excellent electrochemical performances. - Highlights: • Ascorbic acid acts as both an antioxidant and a first-time carbon coating source. • Reaction mechanisms of the synthesis are carefully studied. • Mixed-carbon-coated LiMn_0_._4Fe_0_._6PO_4 nanopowders process excellent high rate and low temperature performances. - Abstract: A novel solvothermal approach with ascorbic acid as both an antioxidant and a first-time carbon coating source is developed to synthesize LiMn_0_._4Fe_0_._6PO_4 nano-particles with a uniform particle size distribution around 150 nm. A calcination step for the second-time carbon coating and further crystallization is adopted following the solvothermal step. The structures and electrochemical properties of the obtained samples are studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Fourier transformation infrared, Infrared carbon-sulfur analyzer and galvanostatic cell cycling. Ascorbic acid plays a crucial role in the formation of uniform carbon layer and nano-particles. Compared with single-carbon-coated LiMn_0_._4Fe_0_._6PO_4 without adding ascorbic acid, the mixed-carbon-coated LiMn_0_._4Fe_0_._6PO_4 shows much better electrochemical performance. It can deliver specific capacities of 154.8 and 128.5 mAh g"−"1 at 1C and 20C, respectively, at 25 °C. Even at −20 °C, its specific capacities are 106.6 and 68.8 mAh g"−"1 at 0.2C and 5C, respectively.

Growth and characterization of thin oriented Co{sub 3}O{sub 4} (111) films obtained by decomposition of layered cobaltates Na{sub x}CoO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Buršík, Josef, E-mail: bursik@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68, Husinec-Řež 1001 (Czech Republic); Soroka, Miroslav, E-mail: soroka@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68, Husinec-Řež 1001 (Czech Republic); Kužel, Radomír, E-mail: kuzel@karlov.mff.cuni.cz [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Mika, Filip, E-mail: filip.mika@isibrno.cz [Institute of Scientific Instruments, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 147, 612 64 Brno (Czech Republic)

2015-07-15

The formation and structural characterization of highly (111)-oriented Co{sub 3}O{sub 4} films prepared by a novel procedure from weakly (001)-oriented Na{sub x}CoO{sub 2} is reported. The Na{sub x}CoO{sub 2} films were deposited on both single crystal and amorphous substrates by chemical solution deposition (CSD) method and crystallized at 700 °C. Subsequently they were transformed into (111)-oriented Co{sub 3}O{sub 4} phase during post-growth annealing at 900 °C. The degree of preferred orientation in Co{sub 3}O{sub 4}, which was determined by phi-scan and pole figure measurements, depends on the content of Na in the starting Na{sub x}CoO{sub 2} phase. Surface morphology of the films was investigated using electron microscopy and atomic force microscopy. - Graphical abstract: Structure of growth twins and possible O{sup 2−} stacking sequences in (111)-oriented Co{sub 3}O{sub 4} thin films on α-Al{sub 2}O{sub 3}(001) prepared by chemical solution deposition through the transformation of (001)-oriented Na{sub x}CoO{sub 2} thin film. - Highlights: • Single phase Co{sub 3}O{sub 4} thin films was prepared by means of chemical solution deposition. • Conditions for γ-Na{sub x}CoO{sub 2} to Co{sub 3}O{sub 4} transformation were optimized. • Growth twinning of Co{sub 3}O{sub 4} films due to two possible O{sup 2−} stacking sequences. • Growth with (pseudo)epitaxial relation Co{sub 3}O{sub 4} (111)[−121]//α-Al{sub 2}O{sub 3} (001)[10−10].

Controlled growth of epitaxial CeO2 thin films with self-organized nanostructure by chemical solution method

DEFF Research Database (Denmark)

Yue, Zhao; Grivel, Jean-Claude

2013-01-01

Chemical solution deposition is a versatile technique to grow oxide thin films with self-organized nanostructures. Morphology and crystallographic orientation control of CeO2 thin films grown on technical NiW substrates by a chemical solution deposition method are achieved in this work. Based...

Nanocrystalline Pd:NiFe2O4 thin films: A selective ethanol gas sensor

International Nuclear Information System (INIS)

Rao, Pratibha; Godbole, R.V.; Bhagwat, Sunita

2016-01-01

In this work, Pd:NiFe 2 O 4 thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe 2 O 4 thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost. - Highlights: • Ethanol gas sensors based on Pd:NiFe 2 O 4 nanoparticle thin film were fabricated. • Pd incorporation in NiFe 2 O 4 matrix inhibits grain growth. • The sensors were more selective to ethanol gas. • Sensors exhibited fast response and recovery when doped with palladium. • Pd:NiFe 2 O 4 thin film sensor displays excellent long–term stability.

Electrochemical and Electronic Charge Transport Properties of Ni-Doped LiMn2O4 Spinel Obtained from Polyol-Mediated Synthesis

Directory of Open Access Journals (Sweden)

Shuo Yang

2018-05-01

Full Text Available LiNi0.5Mn1.5O4 (LNMO spinel has been extensively investigated as one of the most promising high-voltage cathode candidates for lithium-ion batteries. The electrochemical performance of LNMO, especially its rate performance, seems to be governed by its crystallographic structure, which is strongly influenced by the preparation methods. Conventionally, LNMO materials are prepared via solid-state reactions, which typically lead to microscaled particles with only limited control over the particle size and morphology. In this work, we prepared Ni-doped LiMn2O4 (LMO spinel via the polyol method. The cycling stability and rate capability of the synthesized material are found to be comparable to the ones reported in literature. Furthermore, its electronic charge transport properties were investigated by local electrical transport measurements on individual particles by means of a nanorobotics setup in a scanning electron microscope, as well as by performing DFT calculations. We found that the scarcity of Mn3+ in the LNMO leads to a significant decrease in electronic conductivity as compared to undoped LMO, which had no obvious effect on the rate capability of the two materials. Our results suggest that the rate capability of LNMO and LMO materials is not limited by the electronic conductivity of the fully lithiated materials.

Photocatalytic activity of galvanically synthesized nanostructure SnO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Jana, Sumanta, E-mail: sumantajana85@gmail.com [Department of Chemistry, Bengal Engineering and Science University, Botanic Garden, Howrah 711103, WB (India); Mitra, Bibhas Chandra [Department of Physics, Bengal Engineering and Science University, Botanic Garden, Howrah 711103, WB (India); Bera, Pulakesh [Department of Chemistry, Panskura Banamali College, Purba Medinipur, Panskura 721152, WB (India); Sikdar, Moushumi [Department of Chemistry, Bengal Engineering and Science University, Botanic Garden, Howrah 711103, WB (India); Mondal, Anup, E-mail: anupmondal2000@yahoo.co.in [Department of Chemistry, Bengal Engineering and Science University, Botanic Garden, Howrah 711103, WB (India)

2014-07-25

Graphical abstract: Nanostructured porous tin dioxide (SnO{sub 2}) thin films have been synthesized by simple and cost effective galvanic technique. The synthesized porous SnO{sub 2} thin films show excellent photocatalytic activity for degrading methyl orange (MO) dye under light irradiation. The porous morphological grain growth due to annealing is likely to play an active role for this degradation. - Highlights: • SnO{sub 2} thin films have been successfully synthesized by galvanic technique. • A drastic morphological change occurs after annealing as deposited SnO{sub 2} thin films. • Morphological advantage results enhanced photodegradation of dye. - Abstract: The study demonstrates an approach to synthesize nanostructure SnO{sub 2} thin films on TCO (transparent conducting oxide) coated glass substrates by galvanic technique. Aqueous solution of hydrated stannic chloride (SnCl{sub 4}⋅5H{sub 2}O) in potassium nitrate (KNO{sub 3}) solution was used as the working solution. The process involves no sophisticated reactor or toxic chemicals, and proceeds continuously under ambient condition; it provides an economic way of synthesizing nanostructure SnO{sub 2} semiconductor thin films. The influence of sintering temperature on crystalline structure, morphology, electrical and dielectric properties has been studied. A detail analysis of I−V, C−V and dielectrics for annealed SnO{sub 2} thin films have been carried out. The morphological advantage i.e. nanoporous flake like structure allows more efficient transport of reactant molecules to the active interfaces and results a strong photocatalytic activity for degrading methyl orange (MO) dye.

Microwave-assisted synthesis of high-voltage nanostructured LiMn1.5Ni0.5O4 spinel: tuning the Mn3+ content and electrochemical performance

CSIR Research Space (South Africa)

Jafta, CJ

2013-08-01

Full Text Available on the Mn3+ concentration and electrochemistry of the LiMn1.5Ni0.5O4 spinel. It is shown that microwave is capable of tuning the Mn3+ content of the spinel for enhanced electrochemical performance (high capacity, high capacity retention, excellent rate...

Fabrication of assembled ZnO/TiO2 heterojunction thin film transistors using solution processing technique

Science.gov (United States)

Liau, Leo Chau-Kuang; Lin, Yun-Guo

2015-01-01

Ceramic-based metal-oxide-semiconductor (MOS) field-effect thin film transistors (TFTs), which were assembled by ZnO and TiO2 heterojunction films coated using solution processing technique, were fabricated and characterized. The fabrication of the device began with the preparation of ZnO and TiO2 films by spin coating. The ZnO and TiO2 films that were stacked together and annealed at 450 °C were characterized as a p-n junction diode. Two types of the devices, p-channel and n-channel TFTs, were produced using different assemblies of ZnO and TiO2 films. Results show that the p-channel TFTs (p-TFTs) and n-channel TFTs (n-TFTs) using the assemblies of ZnO and TiO2 films were demonstrated by source-drain current vs. drain voltage (IDS-VDS) measurements. Several electronic properties of the p- and n- TFTs, such as threshold voltage (Vth), on-off ratio, channel mobility, and subthreshold swing (SS), were determined by current-voltage (I-V) data analysis. The ZnO/TiO2-based TFTs can be produced using solution processing technique and an assembly approach.

Zirconium doped TiO{sub 2} thin films deposited by chemical spray pyrolysis

Energy Technology Data Exchange (ETDEWEB)

Juma, A. [Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Department of Physics and Astronomy, Botswana International University of Science and Technology, Private bag 16, Palapye (Botswana); Oja Acik, I., E-mail: ilona.oja@ttu.ee [Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Oluwabi, A.T.; Mere, A. [Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Mikli, V.; Danilson, M. [Chair of Semiconductor Materials Technology, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Krunks, M. [Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia)

2016-11-30

Highlights: • Mean crystallite size of TiO{sub 2}:Zr film decreases with increasing [Zr] in the solution. • Zr doping supresses the anatase to rutile transformation process in TiO{sub 2} films. • Band gap of TiO{sub 2}:Zr film is 3.4 eV irrespective of the annealing temperature. - Abstract: Chemical spray pyrolysis (CSP) is a flexible deposition technique that allows for mixing of the precursor solutions in different proportions suitable for doping thin films. The CSP method was used to dope TiO{sub 2} thin films with Zr by adding zirconium(IV) acetylacetonate into a solution of titanium(IV) isopropoxide in ethanol stabilized by acetylacetone at [Zr]/[Ti] of 0, 5, 10 and 20 at%. The Zr-doped TiO{sub 2} thin films were uniform and homogeneous showing much smaller grains than the undoped TiO{sub 2} films. Zr stabilized the anatase phase to temperatures above 800 °C depending on Zr concentration in the spray solution. The concentration of Zr determined by XPS was 6.4 at% for the thin film deposited from the 20 at% solution. According to AFM studies, Zr doping decreased the root mean square roughness of TiO{sub 2} film from 5.9 to 1.1 nm. An XRD study of samples with the highest Zr amount showed the ZrTiO{sub 4} phase started forming after annealing at 800 °C. The optical band gap for TiO{sub 2} decreased from 3.3 eV to 3.0 eV after annealing at 800 °C but for the TiO{sub 2}:Zr(20) film it remained at 3.4 eV. The dielectric constant increased by more than four times with Zr-doping and this was associated with the change in the bond formations caused by substitution of Ti by Zr in the lattice.

Ferroelectric properties of sandwich structured (Bi, La)4T3O12/Pb(Zr, Ti)O3/ (Bi, La)4Ti3O12 thin films on Pt/Ti/SiO2/Si substrates

International Nuclear Information System (INIS)

Bao Dinghua; Wakiya, Naoki; Shinozaki, Kazuo; Mizutani, Nobuyasu

2002-01-01

Sandwich structured (Bi, La) 4 Ti 3 O 12 /Pb(Zr, Ti)O 3 /(Bi, La) 4 Ti 3 O 12 thin films were fabricated on Pt/Ti/SiO 2 /Si substrates, with the intention of simultaneously utilizing the advantages of both (Bi, La) 4 Ti 3 O 12 (BLT) and Pb(Zr, Ti)O 3 (PZT) thin films such as non-fatigue behaviours of BLT and good ferroelectric properties of PZT. Both BLT and PZT layers were prepared by a chemical solution deposition technique. The experiments demonstrated that the sandwich structure showed fatigue-free characteristics at least up to 10 10 switching bipolar pulse cycles under 8 V and excellent retention properties. The sandwich structured thin films also exhibited well-defined hysteresis loops with a remanent polarization (2P r ) of 8.8 μC cm -2 and a coercive field (E c ) of 47 kV cm -1 . The room-temperature dielectric constant and dissipation factor were 210 and 0.031, respectively, at a frequency of 100 kHz. These results suggest that this sandwich structure is a promising material combination for ferroelectric memory applications. (author)

Orientation control of chemical solution deposited LaNiO3 thin films

International Nuclear Information System (INIS)

Ueno, Kengo; Yamaguchi, Toshiaki; Sakamoto, Wataru; Yogo, Toshinobu; Kikuta, Koichi; Hirano, Shin-ichi

2005-01-01

High quality LaNiO 3 (LNO) thin films with preferred orientation could be synthesized on Pt/Ti/SiO 2 /Si substrates at 700 deg. C using the chemical solution deposition method. The homogeneous and stable LNO precursor solutions were prepared using lanthanum isopropoxide and nickel (II) acetylacetonate in a mixed solvent of absolute ethanol and 2-methoxyethanol. The oriented LNO thin films exhibit metallic electro-conduction, and their resistivity at room temperature is sufficiently low for making them an alternative electrode material for functional ceramic thin films

Nanostructured Networks for Energy Storage: Vertically Aligned Carbon Nanotubes (VACNT as Current Collectors for High-Power Li4Ti5O12(LTO//LiMn2O4(LMO Lithium-Ion Batteries

Directory of Open Access Journals (Sweden)

Fabian Pawlitzek

2017-11-01

Full Text Available As a concept for electrode architecture in high power lithium ion batteries, self-supported nanoarrays enable ultra-high power densities as a result of their open pore geometry, which results in short and direct Li+-ion and electron pathways. Vertically aligned carbon nanotubes (VACNT on metallic current collectors with low interface resistance are used as current collectors for the chemical solution infiltration of electroactive oxides to produce vertically aligned carbon nanotubes decorated with in situ grown LiMn2O4 (LMO and Li4Ti5O12 (LTO nanoparticles. The production processes steps (catalyst coating, VACNT chemical vapor deposition (CVD, infiltration, and thermal transformation are all scalable, continuous, and suitable for niche market production to achieve high oxide loadings up to 70 wt %. Due to their unique transport structure, as-prepared nanoarrays achieve remarkably high power densities up to 2.58 kW kg−1, which is based on the total electrode mass at 80 C for LiMn2O4//Li4Ti5O12 full cells. The tailoring of LTO and LMO nanoparticle size (~20–100 nm and VACNT length (array height: 60–200 µm gives insights into the rate-limiting steps at high current for these kinds of nanoarray electrodes at very high C-rates of up to 200 C. The results reveal the critical structural parameters for achieving high power densities in VACNT nanoarray full cells.

Cathodic electrochemical deposition of Magnéli phases TinO2n−1 thin films at different temperatures in acetonitrile solution

International Nuclear Information System (INIS)

Ertekin, Zeliha; Tamer, Uğur; Pekmez, Kadir

2015-01-01

Highlights: • TiO x films were prepared by cathodic electrodeposition in acetonitrile. • One-step electrodeposition of TiO x films without heat treatment process. • Different crystalline Ti n O 2n−1 films (γTi 3 O 5 , λTi 3 O 5 , Ti 4 O 7 , Ti 5 O 9 ) were obtained. - Abstract: The Magnéli phase titanium oxide films prepared by cathodic electrodeposition on indium–tin-oxide coated glass substrates from saturated peroxo-titanium solution in acetonitrile. Electrodeposited brownish semi-conductor thin films were identified via X-ray diffraction, Raman spectroscopy, UV–vis spectroscopy and scanning electron microscopy (SEM). The effects of different potentials and temperatures on the crystallinity of the thin films have been discussed. Ti 3 O 5 , Ti 4 O 7 and Ti 5 O 9 as the most favorable forms of the Ti n O 2n−1 were electrodeposited on ITO electrode at electrochemical deposition potentials and different temperatures. The present investigation reveals that the electrochemical deposition of crystalline Ti n O 2n−1 films by a simple one-step electrodeposition method (without any heat treatment) in acetonitrile solution is possible and very promising as a preparation method for electrochemical applications

Evidence of a splitting of the Mn-O distance and of a large lattice disorder in the charge-ordered phase of LiMn2O4 obtained by EXAFS

International Nuclear Information System (INIS)

Paolone, A.; Castellano, C.; Cantelli, R.; Rousse, G.; Masquelier, C.

2003-01-01

We measured the extended x-ray-absorption fine-structure (EXAFS) spectrum of LiMn 2 O 4 below room temperature in the charge-ordered phase and for comparison at room temperature in the cubic phase. By means of a standard fit procedure we verified that, as reported by neutron-scattering experiments, also at the local level there are two different Mn-O distances below room temperature, which correspond to the surroundings of well-defined Mn 3+ and Mn 4+ ions. This result is different from the ones obtained from previous EXAFS measurements and confirms the physical picture of the phase transition caused by the ordering of charges in contrast to a cooperative Jahn-Teller phenomenon. Moreover a large lattice disorder in the charge-ordered state, which determines a significant static contribution to the EXAFS Debye-Waller factor, has been found. This last result can be considered as the EXAFS spectral mark of charge-order transitions, even in those materials in which there is no clear evidence of the splitting of bond lengths

Thin (111) oriented CoFe{sub 2}O{sub 4} and Co{sub 3}O{sub 4} films prepared by decomposition of layered cobaltates

Energy Technology Data Exchange (ETDEWEB)

Buršík, Josef, E-mail: bursik@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Soroka, Miroslav, E-mail: soroka@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Uhrecký, Róbert, E-mail: uhrecky@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Kužel, Radomír, E-mail: kuzel@karlov.mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Mika, Filip, E-mail: filip.mika@isibrno.cz [Institute of Scientific Instruments, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 147, 612 64 Brno (Czech Republic); Huber, Štěpán, E-mail: stepan.huber@vscht.cz [University of Chemistry and Technology, Faculty of Chemical Technology, Technická 5, 166 28 Prague 6 (Czech Republic)

2016-07-15

Graphical abstract: Pole figures of NaCoO{sub 2} (left) and of CoFe{sub 2}O{sub 4} (right) films formed through the transformation of O3-type NaCoO{sub 2} phase in consequence of sodium deintercalation occurring at 800 °C. Films were prepared by chemical solution deposition on MgO(111) substrate. - Highlights: • Epitaxial Na(CoFe)O{sub 2} thin films by means of chemical solution deposition were prepared. • Oriented spinel films through transformation of Na(CoFe)O{sub 2} were obtained. • Orientation relation to MgO, SrTiO{sub 3} and Zr(Y)O{sub 2} substrates were determined. • Structural aspects of Na(CoFe)O{sub 2} → CoFe{sub 2}O{sub 4} transformation pathway were elucidated. - Abstract: The formation and structural characterization of highly (111)-oriented Co{sub 3}O{sub 4} and CoFe{sub 2}O{sub 4} films prepared by a novel procedure from 00l-oriented NaCoO{sub 2} and Na(CoFe)O{sub 2} is reported. The Na(CoFe)O{sub 2} films were deposited on MgO, SrTiO{sub 3}, LaAlO{sub 3}, and Zr(Y)O{sub 2} single crystals with (100) and (111) orientations by chemical solution deposition method and crystallized at 700 °C. Subsequently they were transformed into (111)-oriented spinel phase during post-growth annealing at 800–1000 °C. Morphology and structure of the films was investigated by means of scanning electron microscopy and X-ray diffraction. While all spinel films exhibit pronounced out-of-plane orientation irrespective of substrate, the rate of in-plane orientation strongly depend on lattice misfit values. Different epitaxial phenomena ranging from true one-to-one epitaxy to the existence of many-to-one epitaxy involving two or more orientations were determined by full 3D texture analysis.

Microstructure and Electrical Properties of Fe,Cu Substituted (Co,Mn)3O4 Thin Films

DEFF Research Database (Denmark)

Szymczewska, Dagmara; Molin, Sebastian; Hendriksen, Peter Vang

2017-01-01

In this work, thin films (~1000 nm) of a pure MnCo2O4 spinel together with its partially substituted derivatives (MnCo1.6Cu0.2Fe0.2O4, MnCo1.6Cu0.4O4, MnCo1.6Fe0.4O4) were prepared by spray pyrolysis and were evaluated for electrical conductivity. Doping by Cu increases the electrical conductivit...

First report on synthesis of ZnFe_2O_4 thin film using successive ionic layer adsorption and reaction: Approach towards solid-state symmetric supercapacitor device

International Nuclear Information System (INIS)

Raut, Shrikant S.; Sankapal, Babasaheb R.

2016-01-01

Highlights: • First report on synthesis of ZnFe_2O_4 thin film using SILAR method. • ZnFe_2O_4 electrode yields the specific capacitance of 471 Fg"−"1 at a scan rate of 5 mV s"−"1 in 1 M NaOH aqueous solution. • Solid-state symmetric supercapacitor device based on ZnFe_2O_4 sandwiched in polyvinyl alcohol (PVA)–LiClO_4 gel electrolyte exhibits voltage windows of 1.0 V. • ZnFe_2O_4-SSS supercapacitor device shows good energy and power density with long cycle life. - Abstract: ZnFe_2O_4 thin film has been synthesized by a simple and low cost successive ionic layer adsorption and reaction (SILAR) method without the use of surfactant or template. The nanoplate composed of nanoparticles with porous surface morphology has been revealed which is beneficial towards supercapacitor application. Formed ZnFe_2O_4 thin film has been tested as an electrode material for supercapacitor through electrochemical analysis. First attempt for SILAR synthesized ZnFe_2O_4 thin film exhibited a specific capacitance of 471 Fg"−"1 at a scan rate of 5 mVs"−"1 in 1 M NaOH aqueous solution. Further, ZnFe_2O_4 solid-state symmetric (SSS) supercapacitor device demonstrated voltage window of 1.0 V with specific capacitance of 32 Fg"−"1, energy density of 4.47 Whkg"−"1 and power density of 277 Wkg"−"1 at 1 Ag"−"1 current density. Such high performance capacitive behavior indicates ZnFe_2O_4 thin film is promising and low cost electrode material towards energy storage devices for various portable electronic systems.

Preparation and characterization of Bi2Sr2CaCu2O8+δ thin films on MgO single crystal substrates by chemical solution deposition

DEFF Research Database (Denmark)

Grivel, Jean-Claude; Kepa, Katarzyna; Hlásek, T.

2013-01-01

Bi2Sr2CaCu2O8 thin films have been deposited on MgO single crystal substrates by spin-coating a solution based on 2-ethylhexanoate precursors. Pyrolysis takes place between 200°C and 450°C and is accompanied by the release of 2-ethylhexanoic acid, CO2 and H2O vapour. Highly c-axis oriented Bi2Sr2Ca...

Photocatalytic properties of porous TiO2/Ag thin films

International Nuclear Information System (INIS)

Chang, C.-C.; Chen, J.-Y.; Hsu, T.-L.; Lin, C.-K.; Chan, C.-C.

2008-01-01

In this study, nanocrystalline TiO 2 /Ag composite thin films were prepared by a sol-gel spin-coating technique. By introducing polystyrene (PS) spheres into the precursor solution, porous TiO 2 /Ag thin films were prepared after calcination at a temperature of 500 deg. C for 4 h. Three different sizes (50, 200, and 400 nm) of PS spheres were used to prepare porous TiO 2 films. The as-prepared TiO 2 and TiO 2 /Ag thin films were characterized by X-ray diffractometry (XRD) and by scanning electron microscopy to reveal structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. When PS spheres of different sizes were introduced after calcination, the as-prepared TiO 2 films exhibited different porous structures. XRD results showed that all TiO 2 /Ag films exhibited a major anatase phase. The photodegradation of porous TiO 2 thin films prepared with 200 nm PS spheres and doped with 1 mol% Ag exhibited the best photocatalytic efficiency where ∼ 100% methylene blue was decomposed within 8 h under UV exposure

A Novel Ternary CoFe2O4/CuO/CoFe2O4 as a Giant Magnetoresistance Sensor

Directory of Open Access Journals (Sweden)

Ramli

2016-12-01

Full Text Available This paper reports the results of a study relating to the synthesis of a novel ternary CoFe2O4/CuO/CoFe2O4 thin film as a giant magnetoresistance (GMR sensor. The CoFe2O4/CuO/CoFe2O4 thin film was prepared onto silicon substrate via DC magnetron sputtering with the targets facing each other. X-ray diffraction was used to determine the structure of the thin film and a 4-point method was used to measure the MR ratio. The GMR ratio is highly dependent on the ferrimagnetic (CoFe2O4 and nonmagnetic (CuO layer thickness. The maximum GMR ratio at room temperature obtained in the CoFe2O4/CuO/CoFe2O4 thin film was 70% when the CoFe2O4 and the CuO layer had a thickness of 62.5 nm and 14.4 nm respectively.

Design and fabrication of ZnO/TiO2-based thin-film inverter circuits using solution processing techniques

International Nuclear Information System (INIS)

Liau, Leo Chau-Kuang; Kuo, Juo-Wei; Chiang, Hsin-Ni

2012-01-01

Novel and cost-effective ceramic-based thin-film inverter circuits, based on two layers of TiO 2 and ZnO films to construct junction field-effect transistors (FETs), were designed and fabricated by solution coating techniques. The double layers of the sol–gel ZnO and TiO 2 films were coated and characterized as a diode according to the current–voltage performance. Two types of FETs, the p-channel (p-FET) and the n-channel (n-FET) devices, were produced using different coating sequences of ZnO and TiO 2 layers. Both of the transistor performances were evaluated by analyzing the source–drain current versus voltage (I ds –V ds ) data with the control of the gate voltage (V g ). The ZnO/TiO 2 -based inverter circuits, such as the complementary-FET device, were further fabricated using the integration of the p-FET and the n-FET. The voltage transfer characteristics of the inverters were estimated by the tests of the input voltage (V in ) versus the output voltage (V out ) for the thin-film inverter circuits. (paper)

Growing barium hexaferrite (BaFe_1_2O_1_9) thin films using chemical solution deposition

International Nuclear Information System (INIS)

Budiawanti, Sri; Soegijono, Bambang

2016-01-01

Barium hexaferrite (BaFe_1_2O_1_9, or simply known as BaM) thin films has been recognized as a potential candidate for microwave-based devices, magnetic recording media and data storage. To grow BaM thin films, chemical solution deposition is conducted using the aqueous solution of metal nitrates, which involves spin coatings on Si substrates. Furthermore, Thermal Gravimeter Analysis (TGA), X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) are applied to evaluate the decomposition behavior, structure, morphology, and magnetic properties of BaM thin films. Additionally, the effects of number of layers variation are also investigated. Finally, magnetic properties analysis indicates the isotropic nature of the films.

Performance improvement for solution-processed high-mobility ZnO thin-film transistors

International Nuclear Information System (INIS)

Li Chensha; Loutfy, Rafik O; Li Yuning; Wu Yiliang; Ong, Beng S

2008-01-01

The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process

Performance improvement for solution-processed high-mobility ZnO thin-film transistors

Energy Technology Data Exchange (ETDEWEB)

Li Chensha; Loutfy, Rafik O [Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L7 (Canada); Li Yuning; Wu Yiliang; Ong, Beng S [Materials Design and Integration Laboratory, Xerox Research Centre of Canada, 2660 Speakman Drive, Mississauga, Ontario L5K 2L1 (Canada)], E-mail: lichnsa@163.com

2008-06-21

The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process.

Preparation and optical properties of ZnGa{sub 2}O{sub 4}:Cr{sup 3+} thin films derived by sol-gel process

Energy Technology Data Exchange (ETDEWEB)

Zhang Weiwei [School of Physics and Nuclear Energy Engineering, Beihang University, No. 37 XueYuan Road, HaiDian District, Beijing 100191 (China); Zhang Junying, E-mail: zjy@buaa.edu.cn [School of Physics and Nuclear Energy Engineering, Beihang University, No. 37 XueYuan Road, HaiDian District, Beijing 100191 (China); Li Yuan; Chen Ziyu; Wang Tianmin [School of Physics and Nuclear Energy Engineering, Beihang University, No. 37 XueYuan Road, HaiDian District, Beijing 100191 (China)

2010-05-01

ZnGa{sub 2}O{sub 4}:Cr{sup 3+} thin films with bright red emission were synthesized using a sol-gel process, characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Auger electron spectroscopy (AES) and UV-vis and fluorescence spectrophotometry measurements. Effects of calcining temperature, film thickness, calcining duration and substrates on the crystal structure and photoluminescent property have been investigated. It is found that the crystallinity, Ga/Zn ratio and band gap energy (E{sub g}) are significant factors influencing optical characteristics, while the nature of substrates affect the surface morphologies of ZnGa{sub 2}O{sub 4}:Cr{sup 3+} thin films.

Nanocrystalline Pd:NiFe{sub 2}O{sub 4} thin films: A selective ethanol gas sensor

Energy Technology Data Exchange (ETDEWEB)

Rao, Pratibha; Godbole, R.V.; Bhagwat, Sunita, E-mail: smb.agc@gmail.com

2016-10-15

In this work, Pd:NiFe{sub 2}O{sub 4} thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe{sub 2}O{sub 4} thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost. - Highlights: • Ethanol gas sensors based on Pd:NiFe{sub 2}O{sub 4} nanoparticle thin film were fabricated. • Pd incorporation in NiFe{sub 2}O{sub 4} matrix inhibits grain growth. • The sensors were more selective to ethanol gas. • Sensors exhibited fast response and recovery when doped with palladium. • Pd:NiFe{sub 2}O{sub 4} thin film sensor displays excellent long–term stability.

Post mortem analysis of fatigue mechanisms in LiNi0.8Co0.15Al0.05O2 - LiNi0.5Co0.2Mn0.3O2 - LiMn2O4/graphite lithium ion batteries

Science.gov (United States)

Lang, Michael; Darma, Mariyam Susana Dewi; Kleiner, Karin; Riekehr, Lars; Mereacre, Liuda; Ávila Pérez, Marta; Liebau, Verena; Ehrenberg, Helmut

2016-09-01

The fatigue of commercial lithium ion batteries after long-term cycling at two different temperatures and cycling rates is investigated. The cells are opened after cycling and post-mortem analysis are conducted. Two main contributions to the capacity loss of the batteries are revealed. The loss of active lithium leads to a relative shift between anodes and cathodes potentials. A growth of the solid electrolyte interface (SEI) on the anode is determined as well as the formation of lithium fluoride species as an electrolyte decomposition product. Those effects are reinforced by increasing cycling rates from 1C/2C (charge/discharge) to 2C/3C as well as by increasing cycling temperatures from 25 °C to 40 °C. The other contribution to the capacity loss originates from a fatigue of the blended cathodes consisting of LiNi0.5Co0.2Mn0.3O2 (NCM), LiNi0.8Co0.15Al0.05O2 (NCA) and LiMn2O4 (LMO). Phase-specific capacity losses and fatigue mechanisms are identified. The layered oxides tend to form microcracks and reveal changes of the surface structure leading to a worsening of the lithium kinetics. The cathode exhibits a loss of manganese at 40 °C cycling temperature. Cycling at 40 °C instead of 25 °C has the major impact on cathodes capacity loss, while cycling at 2C/3C rates barely influences it.

Effect of different solutions on electrochemical deposition of ZnO

International Nuclear Information System (INIS)

Asil, H.; Chinar, K.; Gur, E.; Tuzemen, S.

2010-01-01

ZnO thin films were grown by electrochemical deposition (ECD) onto indium tin oxide using different compounds such as Zn(NO 3 ) 2 , Zn(C 2 H 3 O 2 ) 2 , ZnCl 2 , Zn(ClO 4 ) 2 and different solvents such as dimethylsulfoxide (DMSO) and 18 M deionized water. Furthermore, solutions were prepared using different electrolytes and concentrations in order to determine the optimum deposition parameters of ZnO. All the grown films were characterized by X-ray diffraction, optical absorption and photoluminescence measurement techniques. It is indicated that films grown by using Zn(ClO 4 ) 2 show high crystallinity and optical quality. The X-ray diffraction analysis showed that ZnO thin films which were grown electrochemically in a non-aqueous solution (DMSO) prepared by Zn(ClO 4 ) 2 have highly c-axis preferential orientation. PL measurements showed that ZnO thin films grown in Zn(ClO 4 ) 2 indicates high quality emission characteristics compared to the thin films grown by other solutions

Layered lithium manganese(0.4) nickel(0.4) cobalt(0.2) oxide(2) as cathode for lithium batteries

Science.gov (United States)

Ma, Miaomiao

The lithium ion battery occupies a dominant position in the portable battery market today. Intensive research has been carried out on every part of the battery to reduce cost, avoid environmental hazards, and improve battery performance. The commercial cathode material LiCoO2 has been partially replaced by LiNiyCo1- yO2 in the last two years, and mixed metal oxides have been introduced in the last quarter. From a resources point of view, only about 10 million tons of cobalt deposits are available from the world's minerals. However, there is about 500 times more manganese available than cobalt. Moreover, cobalt itself is not environmentally friendly. The purpose of this work is to find a promising alternative cathode material that can maintain good cycling performance, while at the same time reducing the cost and toxicity. When the cost is lowered, it is then possible to consider the larger scale use of lithium ion batteries in application such as hybrid electric vehicles (HEV). The research work presented in this thesis has focused on a specific composition of a layered lithium transition metal oxide, LiMn0.4Ni 0.4Co0.2O2 with the R3¯m structure. The presence of cobalt plays a critical role in minimizing transition metal migration to the lithium layer, and perhaps also in enhancing the electronic conductivity; however, cobalt is in limited supply and it is therefore more costly than nickel or manganese. The performance of LiMn0.4Ni0.4Co 0.2O2 was investigated and characterized utilizing various techniques an its performance compared with cobalt free LiMn0.5N i0.5O2, as well as with LiMn1/3Ni1/3Co 1/3O2, which is the most extensively studied replacement candidate for LiNiyCo1- yO2, and may be in SONY'S new hybrid cells. First, the structure and cation distribution in LiMn0.4Ni 0.4Co0.2O2 was studied by a combination of X-ray and neutron diffraction experiments. This combination study shows that about 3--5% nickel is present in the lithium layer, while manganese and

Synthesis and photophysical properties of pyrene-functionalized nano-SiO{sub 2} hybrids in solutions and doped-PMMA thin films

Energy Technology Data Exchange (ETDEWEB)

Wu, Wen-Jie; He, Wen-Li; Yu, Hong-Yu [Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433 (China); Huang, Hong-Xiang [State Key Laboratory of Molecular Engineering of Polymers, Fudan University, 220 Handan Road, Shanghai 200433 (China); Chen, Meng [Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433 (China); Qian, Dong-Jin, E-mail: djqian@fudan.edu.cn [Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433 (China)

2017-01-15

Luminescent pyrene-functionalized nano-SiO{sub 2} (nano-SiO{sub 2}Pyr) hybrids were synthesized and characterized using thermogravimetry, infrared, UV–vis absorption and, X-ray photoelectron spectroscopy, as well as field emission transmission electron microscopy (FETEM). The organic substituents immobilized on the nano-SiO{sub 2}Pyr hybrids accounted for approximately 10% of the total weight. Polyethylene glycol 200 (PEG200) was found to be the most suitable solvent to suspend the nano-SiO{sub 2}Pyr hybrids compared to other commonly used organic solvents. FETEM images indicated an average SiO{sub 2} nanoparticle diameter of approximately 12 nm and a 1- to 2-nm thick organic species functionalization layer. Several emission peaks were recorded at wavelengths of 380–580 nm and were designated as emissions arising from either the monomer or excimer of the pyrene substituents. Excimer formation was concentration and solvent polarity dependent, with higher concentrations and a stronger solvent polarity benefiting excimer formation. Further, nano-SiO{sub 2}Pyr hybrids were doped in poly(methyl methacrylate) (PMMA) thin films; fluorescence spectra indicated that the excimer could be formed almost exclusively from neighboring nano-SiO{sub 2}Pyr hybrids. Time-resolved fluorescence decays revealed that the emission lifetimes of nano-SiO{sub 2}Pyr monomers and excimers were approximately 190 ns and 65–100 ns in the PEG200 solution, respectively, which was shortened to 0.45 ns to tens of ns in doped PMMA thin films, depending on the nano-hybrid concentration. Thus, the present study not only provides a method to prepare luminescent nano-materials but also a route to investigate excimer formation in solutions and thin films. - Highlights: • Luminescent pyrene-functionalized nano-SiO{sub 2}Pyr hybrids were prepared. • A 1- to 2- nm thick organic functionalization layer on nano-SiO{sub 2} was observed. • Formation of pyrene excimer was concentration and solvent

THE THICKNESS DEPENDENCE OF OXYGEN PERMEABILITY IN SOL-GEL DERIVED CGO-COFE2O4 THIN FILMS ON POROUS CERAMIC SUBSTRATES: A SPUTTERED BLOCKING LAYER FOR THICKNESS CONTROL

Energy Technology Data Exchange (ETDEWEB)

Brinkman, K

2009-01-08

Mixed conductive oxides are a topic of interest for applications in oxygen separation membranes as well as use in producing hydrogen fuel through the partial oxidation of methane. The oxygen flux through the membrane is governed both by the oxygen ionic conductivity as well as the material's electronic conductivity; composite membranes like Ce{sub 0.8}Gd{sub 0.2}O{sub 2-{delta}} (CGO)-CoFe{sub 2}O{sub 4} (CFO) use gadolinium doped ceria oxides as the ionic conducting material combined with cobalt iron spinel which serves as the electronic conductor. In this study we employ {approx} 50 nm sputtered CeO{sub 2} layers on the surface of porous CGO ceramic substrates which serve as solution 'blocking' layers during the thin film fabrication process facilitating the control of film thickness. Films with thickness of {approx} 2 and 4 microns were prepared by depositing 40 and 95 separate sol-gel layers respectively. Oxygen flux measurements indicated that the permeation increased with decreasing membrane thickness; thin film membrane with thickness on the micron level showed flux values an order of magnitude greater (0.03 {micro}mol/cm{sup 2} s) at 800 C as compared to 1mm thick bulk ceramic membranes (0.003 {micro}mol/cm{sup 2}).

Synthesis of nanocrystalline TiO2 thin films by liquid phase ...

Indian Academy of Sciences (India)

WINTEC

goes degradation efficiently in presence of TiO2 thin films by exposing its aqueous solution to .... Figure 6. Photodegradation of IGOR organic dye by a. bare TiO2 thin film and b. ... Meng L-J and Dos Santos M P 1993 Thin Solid Films 226 22.

Nanocrystalline Pd:NiFe2O4 thin films: A selective ethanol gas sensor

Science.gov (United States)

Rao, Pratibha; Godbole, R. V.; Bhagwat, Sunita

2016-10-01

In this work, Pd:NiFe2O4 thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe2O4 thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost.

Combustion synthesis of LiMn{sub 2}O{sub 4} with citric acid and the effect of post-heat treatment

Energy Technology Data Exchange (ETDEWEB)

Han, Y.S. [Korea Advanced Istitute of Science and Technology, Taejeon (Korea); Son, J.T. [Dong-A Electric Equipment Co. LTD., Seoul (Korea); Kim, H.G. [Korea Advanced Istitute of Science and Technology, Taejeon (Korea); Jung, H.T. [Dongshin University, Chonnam (Korea)

2001-04-01

Combustion process with citrate was used to produce the LiMn{sub 2}O{sub 4} powder. Precursors are pre-ignited in open air followed by post-heating in the range from 600 deg. C to 800 deg. C for 4 h. With varying the molar ration (R) of ethylene glycol (EG) to citric acid (CA) from 0 to 4, the effect of EG content on powder characteristics is evaluated. Vacuum drying promote the auto-ignition at room temperature. With small addition of EG metal ion was selectively segregated with organic substances and undesired lithium evaporation occurred during post-heating. LiMn {sub 2}O{sub 4} phase which is produced by combustion reaction was decomposed back to Mn {sub 3}O{sub 4} because the reaction temperature was higher than 950 deg. C. With increasing EG content, the homogeneity of LiMn {sub 2}O{sub 4} powder increased and specific surface area increased. And lithium evaporation during vacuum drying and/or ignition also increased. (author). 18 refs., 1 tab., 11 figs.

MOCVD growth of transparent conducting Cd2SnO4 thin films

International Nuclear Information System (INIS)

Metz, A.W.; Poeppelmeier, K.R.; Marks, T.J.; Lane, M.A.; Kannewurt, C.R.

2004-01-01

The first preparation of transparent conducting Cd 2 SnO 4 thin films by a simple MOCVD process is described. As-deposited films using Cd(hfa) 2 (TMEDA) (Figure), at 365 C are found to be highly crystalline with a relatively wide range of grain size of 100-300 nm. XRD indicates a cubic spinel Cd 2 SnO 4 crystal structure and the possible presence of a small amount of CdO. The films exhibit conductivities of 2170 S/cm and a bandgap of 3.3 eV, rivaling those of commercial tin-doped indium oxide. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

Effect of yttrium doping on the dielectric properties of CaCu{sub 3}Ti{sub 4}O{sub 12} thin film produced by chemical solution deposition

Energy Technology Data Exchange (ETDEWEB)

Saji, Viswanathan S., E-mail: vssaji@chosun.ac.k [Chosun University, College of Dentistry and 2nd Stage of Brain Korea 21 for College of Dentistry, Gwangju-501-759 (Korea, Republic of); Choe, Han Cheol [Chosun University, College of Dentistry and 2nd Stage of Brain Korea 21 for College of Dentistry, Gwangju-501-759 (Korea, Republic of)

2009-05-29

Pure and yttrium substituted CaCu{sub 3}Ti{sub 4-x}Y{sub x}O{sub 12-x/} {sub 2} (x = 0, 0.02, 0.1) thin films were prepared on boron doped silica substrate employing chemical solution deposition, spin coating and rapid thermal annealing. The phase and microstructure of the sintered films were examined using X-ray diffraction and scanning electron microscopy. Dielectric properties of the films were measured at room temperature using electrochemical impedance spectroscopy. Highly ordered polycrystalline CCTO thin film with bimodal grain size distribution was achieved at a sintering temperature of 800 {sup o}C. Yttrium doping was found to have beneficial effects on the dielectric properties of CCTO thin film. Dielectric parameters obtained for a CaCu{sub 3}Ti{sub 4-x}Y{sub x}O{sub 12-x} {sub /2} (x = 0.02) film at 1 KHz were k {approx} 2700 and tan {delta} {approx} 0.07.

Magnetic and optical properties of MgAl2O4-(Ni0.5Zn0.5Fe2O4 thin films prepared by pulsed laser deposition

Directory of Open Access Journals (Sweden)

Takeshi Misu, Naonori Sakamoto, Kazuo Shinozaki, Nobuyasu Adachi, Hisao Suzuki and Naoki Wakiya

2011-01-01

Full Text Available Thin films composed of MgAl2O4 and (Ni0.5Zn0.5Fe2O4 ([MA(100-x-NZFx] films were grown on fused SiO2 substrates by pulsed laser deposition. X-ray diffraction measurements revealed that the films were polycrystalline, and that their lattice constant varied linearly with composition, indicating the formation of a solid solution. The film with x=60 was paramagnetic and those with x ≥ 70 were ferromagnetic. The films had a transparency above 75% in the visible range, but the transparency decreased with the x value. The optical band gaps were 2.95, 2.55, 2.30 and 1.89 eV for x=20, 40, 60, 80 and 100, respectively. The Faraday rotation angle increased with x in the visible range, and the film with x=70 exhibited a value of 2000 degrees cm-1 at 570 nm, which is comparable to the rotation angle of Y3Fe5O12. Owing to their high transparency, which extends into the visible range, the [MA(100-x-NZFx] films can be used in novel magneto-optical devices.

Osmotic and activity coefficients of aqueous NaTcO4 and NaReO4 solutions at 250C

International Nuclear Information System (INIS)

Boyd, G.E.

1978-01-01

Isopiestic vapor-pressure comparison experiments were performed with aqueous binary sodium perchlorate, pertechnetate, and perrhenate solutions to concentrations of approximately 8.5 m. Osmotic coefficients for these solutions and mean molal ionic activity coefficients for NaTcO 4 and NaReO 4 were derived from the isotonic molalities. Pitzer's treatment was applied to describe the concentration dependence of the osmotic coefficients of NaClO 4 , NaTcO 4 , and NaReO 4 , and the implications of the parameters derived from a least-squares fit are discussed in terms of solvent structure and interionic forces. 4 tables, 1 figure

Structural and corrosive properties of ZrO2 thin films on zircaloy-4 by RF reactive magnetron sputtering

International Nuclear Information System (INIS)

Kim, Soo Ho; Lee, Kwang Hoon; Ko, Jae Hwan; Yoon, Young Soo; Baek, Jong Hyuk; Lee, Sang Jin

2006-01-01

Zirconium-oxide (ZrO 2 ) thin films as protective layers were grown on a Zircaloy-4 (Z-4) cladding material as a substrate by RF reactive magnetron sputtering at room temperature. To investigate the effect of plasma immersion on the structural and the corrosive properties of the as-grown ZrO 2 thin film, we immersed Z-4 in plasma during the deposition process. X-ray diffraction (XRD) measurements showed that the as-grown ZrO 2 thin films immersed in plasma had cubic, well as monoclinic and tetragonal, phases whereas those immersed in the plasma had monoclinic and tetragonal phases only. Atomic force microscopy (AFM) measurements of the surface morphology showed that the surface roughness of the as-grown ZrO 2 thin films immersed in plasma was larger than that of the films not immersed in plasma. In addition, the corrosive property of the as-grown ZrO 2 thin films immersed in the plasma was characterized using the weight gains of Z-4 after the corrosion test. Compared with the non-immersed films, the weight gains of the immersed films were larger. These results indicate that the ZrO 2 films immersed in plasma cannot protect Z-4 from corrosive phenomena.

Spray pyrolysed Ru:TiO2 thin film electrodes prepared for electrochemical supercapacitor

Science.gov (United States)

Fugare, B. Y.; Thakur, A. V.; Kore, R. M.; Lokhande, B. J.

2018-04-01

Ru doped TiO2 thin films are prepared by using 0.06 M aqueous solution of potassium titanium oxalate (pto), and 0.005 M aqueous solution of ruthenium tri chloride (RuCl3) precursors. The deposition was carried on stainless steel (SS) by using well known ultrasonic spray pyrolysis technique (USPT) at 723° K by maintaining the spray rate 12 cc/min and compressed air flow rate 10 Lmin-1. Prepared Ru:TiO2 thin films were characterized by structurally, morphologically and electrochemically. Deposited RuO2 shows amorphous structure and TiO2 shows tetragonal crystal structure with rutile as prominent phase at very low decomposition temperature. SEM micrographs of RuO2 exhibits porous, interconnected, spherical grains type morphology and TiO2 shows porous, nanorods and nanoplates like morphology and also Ru doped TiO2 shows porous, spherical, granular and nanorods type morphology. The electrochemical cyclic voltammetery shows mixed capacitive behavior. The achieved highest value of specific capacitance 2692 F/g was Ru doped TiO2 electrode in 0.5 M H2SO4.

Structural and magnetic properties of [001] CoCr2O4 thin films

NARCIS (Netherlands)

Guzman, Roger; Heuver, Jeroen; Matzen, Sylvia; Magen, Cesar; Noheda, Beatriz

2017-01-01

The spinel CoCr2O4 (CCO) is one of the few bulk multiferroics with net magnetic moment. However, studies on the properties of CCO thin films are scarce. Here, we investigate the interplay between microstructure and magnetism of a series of CCO epitaxial thin films by means of x-ray diffraction,

Dependency of the band gap of electrodeposited Copper oxide thin films on the concentration of copper sulfate (CuSO4.5H2O) and pH in bath solution for photovoltaic applications

KAUST Repository

Islam, Md. Anisul

2016-03-10

In this study, Copper oxide thin films were deposited on copper plate by electrodeposition process in an electrolytic bath containing CuSO4.5H2O, 3M lactic acid and NaOH. Copper oxide films were electrodeposited at different pH and different concentration of CuSO4.5H2O and the optical band gap was determined from their absorption spectrum which was obtained from UV-Vis absorption spectroscopy. It was found that copper oxide films which were deposited at low concentration of CuSO4.5H2O have higher band gap than those deposited at higher bath concentration. The band gap of copper oxide films also significantly changes with pH of the bath solution. It was also observed that with the increase of the pH of bath solution band gap of copper oxide film decreased. © 2015 IEEE.

Synthesis of nanocrystalline nickel-zinc ferrite (Ni0.8Zn0.2Fe2O4) thin films by chemical bath deposition method

International Nuclear Information System (INIS)

Pawar, D.K.; Pawar, S.M.; Patil, P.S.; Kolekar, S.S.

2011-01-01

Graphical abstract: Display Omitted Research highlights: → We have successfully synthesized nickel-zinc ferrite (Ni 0.8 Zn 0.2 Fe 2 O 4 ) thin films on stainless steel substrates using a low temperature chemical bath deposition method. → The surface morphological study showed the compact flakes like morphology. → The as-deposited thin films are hydrophilic (10 o o ) whereas the annealed thin films are super hydrophilic (θ o ) in nature. → Ni 0.8 Zn 0.2 Fe 2 O 4 thin films could be used in supercapacitor. - Abstract: The nickel-zinc ferrite (Ni 0.8 Zn 0.2 Fe 2 O 4 ) thin films have been successfully deposited on stainless steel substrates using a chemical bath deposition method from alkaline bath. The films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), static water contact angle and cyclic voltammetry measurements. The X-ray diffraction pattern shows that deposited Ni 0.8 Zn 0.2 Fe 2 O 4 thin films were oriented along (3 1 1) plane. The FTIR spectra showed strong absorption peaks around 600 cm -1 which are typical for cubic spinel crystal structure. SEM study revealed compact flakes like morphology having thickness ∼1.8 μm after air annealing. The annealed films were super hydrophilic in nature having a static water contact angle (θ) of 5 o .The electrochemical supercapacitor study of Ni 0.8 Zn 0.2 Fe 2 O 4 thin films has been carried out in 6 M KOH electrolyte. The values of interfacial and specific capacitances obtained were 0.0285 F cm -2 and 19 F g -1 , respectively.

High-temperature x-ray diffraction study of HfTiO4-HfO2 solid solutions

International Nuclear Information System (INIS)

Carpenter, D.A.

1975-01-01

High-temperature x-ray diffraction techniques were used to determine the axial thermal expansion curves of HfTiO 4 -HfO 2 solid solutions as a function of composition. Data show increasing anisotropy with increasing HfO 2 content. An orthorhombic-to-monoclinic phase transformation was detected near room temperature for compositions near the high HfO 2 end of the orthorhombic phase field and for compositions within the two-phase region (HfTiO 4 solid solution plus HfO 2 solid solution). An orthorhombic-to-cubic phase transformation is indicated by data from oxygen-deficient materials at greater than 1873 0 K. (U.S.)

Electrical and optical properties of thermally-evaporated thin films from A2[TiO(C2O4)2] (A = K, PPh4) and 1,8-dihydroxyanthraquinone

International Nuclear Information System (INIS)

Carbia-Ruelas, E.; Sanchez-Vergara, M.E.; Garcia-Montalvo, V.; Morales-Saavedra, O.G.; Alvarez-Bada, J.R.

2011-01-01

In this work, the synthesis of molecular materials formed from A 2 [TiO(C 2 O 4 ) 2 ] (A = K, PPh4) and 1,8 dihydroxyanthraquinone is reported. The synthesized materials were characterized by atomic force microscopy (AFM), infrared (IR) and ultraviolet-visible (UV-vis) spectroscopy. IR spectroscopy showed that the molecular-material thin-films, deposited by vacuum thermal evaporation, exhibit the same intra-molecular vibration modes as the starting powders, which suggests that the thermal evaporation process does not alter the initial chemical structures. Electrical transport properties were studied by dc conductivity measurements. The electrical activation energies of the complexes, which were in the range of 0.003-1.16 eV, were calculated from Arrhenius plots. Optical absorption studies in the wavelength range of 190-1090 nm at room temperature showed that the optical band gaps of the thin films were around 1.9-2.3 eV for direct transitions Eg d . The cubic NLO effects were substantially enhanced for materials synthesized from K 2 [TiO(C 2 O 4 ) 2 ], where χ (3) (-3ω; ω, ω, ω) values in the promising range of 10 -12 esu have been evaluated.

TiO2 and Cu/TiO2 Thin Films Prepared by SPT

Directory of Open Access Journals (Sweden)

S. S. Roy

2015-12-01

Full Text Available Titanium oxide (TiO2 and copper (Cu doped titanium oxide (Cu/TiO2 thin films have been prepared by spray pyrolysis technique. Titanium chloride (TiCl4 and copper acetate (Cu(CH3COO2.H2O were used as source of Ti and Cu. The doping concentration of Cu was varied from 1-10 wt. %. The X-ray diffraction studies show that TiO2 thin films are tetragonal structure and Cu/TiO2 thin films implies CuO has present with monoclinic structure. The optical properties of the TiO2 thin films have been investigated as a function of Cu-doping level. The optical transmission of the thin films was found to increase from 88 % to 94 % with the addition of Cu up to 8 % and then decreases for higher percentage of Cu doping. The optical band gap (Eg for pure TiO2 thin film is found to be 3.40 eV. Due to Cu doping, the band gap is shifted to lower energies and then increases further with increasing the concentration of Cu. The refractive index of the TiO2 thin films is found to be 2.58 and the variation of refractive index is observed due to Cu doped. The room temperature resistivity of the films decreases with increasing Cu doping and is found to be 27.50 - 23.76 W·cm. It is evident from the present study that the Cu doping promoted the thin film morphology and thereby it is aspect for various applications.

Fabrication of amorphous InGaZnO thin-film transistor with solution processed SrZrO3 gate insulator

Science.gov (United States)

Takahashi, Takanori; Oikawa, Kento; Hoga, Takeshi; Uraoka, Yukiharu; Uchiyama, Kiyoshi

2017-10-01

In this paper, we describe a method of fabrication of thin film transistors (TFTs) with high dielectric constant (high-k) gate insulator by a solution deposition. We chose a solution processed SrZrO3 as a gate insulator material, which possesses a high dielectric constant of 21 with smooth surface. The IGZO-TFT with solution processed SrZrO3 showed good switching property and enough saturation features, i.e. field effect mobility of 1.7cm2/Vs, threshold voltage of 4.8V, sub-threshold swing of 147mV/decade, and on/off ratio of 2.3×107. Comparing to the TFTs with conventional SiO2 gate insulator, the sub-threshold swing was improved by smooth surface and high field effect due to the high dielectric constant of SrZrO3. These results clearly showed that use of solution processed high-k SrZrO3 gate insulator could improve sub-threshold swing. In addition, the residual carbon originated from organic precursors makes TFT performances degraded.

Investigation of positive electrode materials based on MnO2 for lithium batteries

International Nuclear Information System (INIS)

Le, My Loan Phung; Lam, Thi Xuan Binh; Pham, Quoc Trung; Nguyen, Thi Phuong Thoa

2011-01-01

Various composite materials of MnO 2 /C have been synthesized by electrochemical deposition and then used for the synthesis of lithium manganese oxide (LiMn 2 O 4 ) spinel as a cathode material for lithium ion batteries. The structure and electrochemical properties of electrode materials based on MnO 2 /C, spinel LiMn 2 O 4 and doped spinel LiNi 0.5 Mn 1.5 O 4 have been studied. The influence of synthesis conditions on the structural and electrochemical properties of synthesized materials was investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electronic microscopy (TEM) and charge–discharge experiments. Some of the studied materials exhibit good performance of cycling and discharge capacity

Synthesis and characterization of nanosized lithium manganate and its derivatives

Science.gov (United States)

Iqbal, Muhammad Javed; Zahoor, Sabia

Spinel lithium manganese oxide, LiMn 2O 4 and its derivatives are prepared by the sol-gel method. The lattice constant of the pure material is calculated as 8.23 Å. Different transition metal cations of chromium, iron, cobalt, nickel, copper and zinc (0.05 and 0.15 M) are doped in place of manganese in the LiMn 2O 4. X-ray powder diffraction data show that the spinel framework preserved its integrity upon doping. Formation of a single phase and the purity of the samples are confirmed by X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The crystallite size of the samples is calculated by use of the Scherrer formula and is found to be within a range of 43-66 nm. The electrical conductivity of the samples is determined over a temperature range of 200-300 K by means of four-point probe method. An increasing trend of conductivity with increase in temperature is noted for all the samples. The parent compound LiMn 2O 4 has a conductivity value of 3.47 × 10 -4 ohm -1 cm -1 at room temperature. This value increases on doping with the above-mentioned transition metal cations.

Electrical properties of solution-deposited ZnO thin-film transistors by low-temperature annealing.

Science.gov (United States)

Lim, Chul; Oh, Ji Young; Koo, Jae Bon; Park, Chan Woo; Jung, Soon-Won; Na, Bock Soon; Chu, Hye Yong

2014-11-01

Flexible oxide thin-film transistors (Oxide-TFTs) have emerged as next generation transistors because of their applicability in electronic device. In particular, the major driving force behind solution-processed zinc oxide film research is its prospective use in printing for electronics. A low-temperature process to improve the performance of solution-processed n-channel ZnO thin-film transistors (TFTs) fabricated via spin-coating and inkjet-printing is introduced here. ZnO nanoparticles were synthesized using a facile sonochemical method that was slightly modified based on a previously reported method. The influence of the annealing atmosphere on both nanoparticle-based TFT devices fabricated via spin-coating and those created via inkjet printing was investigated. For the inkjet-printed TFTs, the characteristics were improved significantly at an annealing temperature of 150 degrees C. The field effect mobility, V(th), and the on/off current ratios were 3.03 cm2/Vs, -3.3 V, and 10(4), respectively. These results indicate that annealing at 150 degrees C 1 h is sufficient to obtain a mobility (μ(sat)) as high as 3.03 cm2/Vs. Also, the active layer of the solution-based ZnO nanoparticles allowed the production of high-performance TFTs for low-cost, large-area electronics and flexible devices.

High performance In2O3 thin film transistors using chemically derived aluminum oxide dielectric

KAUST Repository

Nayak, Pradipta K.

2013-07-18

We report high performance solution-deposited indium oxide thin film transistors with field-effect mobility of 127 cm2/Vs and an Ion/Ioff ratio of 106. This excellent performance is achieved by controlling the hydroxyl group content in chemically derived aluminum oxide (AlOx) thin-film dielectrics. The AlOx films annealed in the temperature range of 250–350 °C showed higher amount of Al-OH groups compared to the films annealed at 500 °C, and correspondingly higher mobility. It is proposed that the presence of Al-OH groups at the AlOx surface facilitates unintentional Al-doping and efficient oxidation of the indium oxide channel layer, leading to improved device performance.

High performance In2O3 thin film transistors using chemically derived aluminum oxide dielectric

KAUST Repository

Nayak, Pradipta K.; Hedhili, Mohamed N.; Cha, Dong Kyu; Alshareef, Husam N.

2013-01-01

We report high performance solution-deposited indium oxide thin film transistors with field-effect mobility of 127 cm2/Vs and an Ion/Ioff ratio of 106. This excellent performance is achieved by controlling the hydroxyl group content in chemically derived aluminum oxide (AlOx) thin-film dielectrics. The AlOx films annealed in the temperature range of 250–350 °C showed higher amount of Al-OH groups compared to the films annealed at 500 °C, and correspondingly higher mobility. It is proposed that the presence of Al-OH groups at the AlOx surface facilitates unintentional Al-doping and efficient oxidation of the indium oxide channel layer, leading to improved device performance.

Nanocrystalline Cobalt-doped SnO2 Thin Film: A Sensitive Cigarette Smoke Sensor

Directory of Open Access Journals (Sweden)

Patil Shriram B.

2011-11-01

Full Text Available This article discusses a sensitive cigarette smoke sensor based on Cobalt doped Tin oxide (Co-SnO2 thin films deposited on glass substrate by a conventional Spray Pyrolysis technique. The Co-SnO2 thin films have been characterized by X-ray Diffraction (XRD, Scanning Electron Microscopy (SEM and Energy Dispersive X-ray Spectroscopy (EDAX. The XRD spectrum shows polycrystalline nature of the film with a mixed phase comprising of SnO2 and Co3O4. The SEM image depicts uniform granular morphology covering total substrate surface. The compositional analysis derived using EDAX confirmed presence of Co in addition to Sn and O in the film. Cigarette smoke sensing characteristics of the Co-SnO2 thin film have been studied under atmospheric condition at different temperatures and smoke concentration levels. The sensing parameters such as sensitivity, response time and recovery time are observed to be temperature dependent, exhibiting better results at 330 oC.

Improved photoelectrochemical performance of BiVO4/MoO3 heterostructure thin films

Science.gov (United States)

Kodan, Nisha; Mehta, B. R.

2018-05-01

Bismuth vanadate (BiVO4) and Molybdenum trioxide (MoO3) thin films have been prepared by RF sputtering technique. BiVO4 thin films were deposited on indium doped tin oxide (In: SnO2; ITO) substrates at room temperature and 80W applied rf power. The prepared BiVO4 thin films were further annealed at 450°C for 2 hours in air to obtain crystalline monoclinic phase and successively coated with MoO3 thin films deposited at 150W rf power and 400°C for 30 minutes. The effect of coupling BiVO4 and MoO3 on the structural, optical and photoelectrochemical (PEC) properties have been studied. Optical studies reveal that coupling of BiVO4 and MoO3 results in improvement of optical absorption in visible region of solar spectrum. PEC study shows approximate 3-fold and 38-fold increment in photocurrent values of BiVO4/MoO3 (0.38 mA/cm2) heterostructure thin film as compared to MoO3 (0.15 mA/cm2) and BiVO4 (10 µA/cm2) thin films at applied bias of 1 V vs Ag/AgCl in 0.5 M Na2SO4 (pH=7) electrolyte.

An electrochemical study of the systems Li1+-xV2O4 and Li1-xVO2 (0≤x≤1)

International Nuclear Information System (INIS)

De Picciotto, L.A.; Thackeray, M.M.; Pistoia, G.

1988-01-01

Electrochemical properties of the systems Li 1±x V 2 O 4 (0≤x≤1), Li 1-x VO 2 (0≤x 2 O 4 is reversible, which confirms that lithium may be cycled, topotactically, in and out of the Li 1+x V 2 O 4 spinel structure. Delithiation of the LiV 2 O 4 spinel is irreversible; during this process the vanadium ions migrate through the oxide layers. This results in a defect rocksalt phase, which can, in turn, be relithiated by a different mechanism. Lithium extraction for the layered compound LiVO 2 yields a structure similar to the delithiated LiV 2 O 4 product. The spinel-derived compounds Li 1 +-x/V 2 O 4 (0 -3 Ω -1 cm -1 at x=0 and 10 -6 Ω -1 cm -1 at x=1. Lithium diffusion rates in Li 1±x V 2 O 4 samples increase with lithiation from D=4x10 -10 cm 2 /s in LiV 2 O 4 to D=6x10 -8 cm 2 /s in Li 2 V 2 O 4 . Intermediate values of D are obtained in the delithiated compound Li 0.28 V 2 O 4 and in the layered oxide LiVO 2 ; significantly lower values of D, viz. 1x10 -11 cm 2 /s and 4x10 -11 cm 2 /s , are found in the spinels LiMn 2 O 4 and Fe 3 O 4 respectively. 28 refs.; 5 figs.; 1 table

Synthesis of TiO{sub 2} sol in a neutral solution using TiCl{sub 4} as a precursor and H{sub 2}O{sub 2} as an oxidizing agent

Energy Technology Data Exchange (ETDEWEB)

Sasirekha, Natarajan; Rajesh, Baskaran [Department of Chemical Engineering, National Central University, Chung-Li 320, Taiwan (China); Chen, Yu-Wen, E-mail: ywchen@cc.ncu.edu.t [Department of Chemical Engineering, National Central University, Chung-Li 320, Taiwan (China)

2009-11-02

Nanosize TiO{sub 2} thin film on glass substrate was obtained through dip-coating method using TiO{sub 2} sol. Suspended nanosize TiO{sub 2} sols with anatase structure in aqueous solution were synthesized by sol-gel method using TiCl{sub 4} as a precursor. TiCl{sub 4} was reacted with an aqueous solution of NH{sub 4}OH to form Ti(OH){sub 4}, and H{sub 2}O{sub 2} was then added to form peroxo titanic acid. It was further heated in water and converted to TiO{sub 2}. The effects of the preparation parameters, viz., pH value of the Ti(OH){sub 4} gel, concentration of H{sub 2}O{sub 2}, and heating temperature and time, on the properties of the TiO{sub 2} sol were investigated. The materials were characterized by X-ray diffraction, Fourier transform-infrared spectroscopy, and transmission electron microscopy. The results showed that the primary TiO{sub 2} particles were rhombus with the major axis ca. 10 nm and minor axis ca. 4 nm, and were in anatase structure. The sol was excellent in dispersibility and was stable in neutral and even slight basic conditions for at least 2 years without causing agglomeration. The best preparation condition was optimized with the pH value of Ti(OH){sub 4} gel at 8, H{sub 2}O{sub 2}/TiO{sub 2} mole ratio of 2, and heating at 97 {sup o}C for 8 h. The transparent adherent TiO{sub 2} film on glass substrates exhibits strong hydrophilicity after illuminating with ultraviolet light and it can be used as an efficient photocatalyst.

Metal-assisted chemical etching in HF/Na2S2O8 OR HF/KMnO4 produces porous silicon

NARCIS (Netherlands)

Hadjersi, T.; Gabouze, N.; Kooij, Ernst S.; Zinine, A.; Zinine, A.; Ababou, A.; Chergui, W.; Cheraga, H.; Belhousse, S.; Djeghri, A.

2004-01-01

A new metal-assisted chemical etching method using Na2S2O8 or KMnO4 as an oxidizing agent was proposed to form a porous silicon layer on a highly resistive p-type silicon. A thin layer of Ag or Pd is deposited on the Si(100) surface prior to immersion in a solution of HF and Na2S2O8 or HF and KMnO4.

Preparation and properties of KCl-doped Cu2O thin film by electrodeposition

International Nuclear Information System (INIS)

Yu, Xiaojiao; Li, Xinming; Zheng, Gang; Wei, Yuchen; Zhang, Ama; Yao, Binghua

2013-01-01

With the indium tin oxide-coated glass as working electrode, cuprous oxide thin film is fabricated by means of electrodeposition. The effects of KCl doped and annealing treatment upon Cu 2 O thin film morphology, surface resistivity, open-circuit voltage, electric conduction types and visible light response are studied. The research results indicate that KCl doped has a great effect upon Cu 2 O crystal morphology, thus, making Cu 2 O thin film surface resistivity drop, and the open-circuit voltage increase and that electric conduction types are transformed from p type into n type, and the visible light (400–500 nm) absorption rate is slightly reduced. Annealing treatment can obviously decrease Cu 2 O thin film surface resistivity and improve its open-circuit voltage. When KCl concentration in electrolytic solution reaches 7 mmol/L, Cu 2 O thin film morphology can be changed from the dendritic crystal into the cubic crystal and Cu 2 O thin film surface resistivity decreases from the initial 2.5 × 10 6 Ω cm to 8.5 × 10 4 Ω cm. After annealing treatment at 320 °C for 30 min, the surface resistivity decreases to 8.5 × 10 2 Ω cm, and the open-circuit voltage increases from the initial 3.1 mV to 79.2 mV.

Application of Ti/RuO{sub 2}-Ta{sub 2}O{sub 5} electrodes in the electrooxidation of ethanol and derivants: Reactivity versus electrocatalytic efficiency

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, J.; De Andrade, A.R. [Departamento de Quimica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, 14040-9010 Ribeirao Preto, SP (Brazil); Purgato, F.L.S. [Departamento de Quimica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, 14040-9010 Ribeirao Preto, SP (Brazil); Equipe Electrocatalyse, UMR 6503 CNRS, Universite de Poitiers, 40 Avenue du Recteur Pineau 86022 Poitiers Cedex (France); Kokoh, K.B.; Leger, J.-M. [Equipe Electrocatalyse, UMR 6503 CNRS, Universite de Poitiers, 40 Avenue du Recteur Pineau 86022 Poitiers Cedex (France)

2008-11-15

The influence of the preparation method on the performance of RuO{sub 2}-Ta{sub 2}O{sub 5} electrodes was evaluated toward the ethanol oxidation reaction (EOR). Freshly prepared RuO{sub 2}-Ta{sub 2}O{sub 5} thin films containing between 30 and 80 at.% Ru were prepared by two different methods: the modified Pechini-Adams method (DPP) and standard thermal decomposition (STD). Electrochemical investigation of the electrode containing RuO{sub 2}-Ta{sub 2}O{sub 5} thin films was conducted as a function of electrode composition in a 0.5-mol dm{sup -3} H{sub 2}SO{sub 4} solution, in the presence and absence of ethanol and its derivants (acetaldehyde and acetic acid). At a low ethanol concentration (5 mmol dm{sup -3}), ethanol oxidation leads to high yields of acetic acid and CO{sub 2}. On the other hand, an increase in ethanol concentration (15-1000 mmol dm{sup -3}) favors acetaldehyde formation, so acetic acid and CO{sub 2} production is hindered, in this case. Electrodes prepared by DPP provide higher current efficiency than STD electrodes for all the investigated ethanol concentrations. This may be explained by the increase in electrode area obtained with the DPP preparation method compared with STD. (author)

Electrochemical behavior and assembly of tetranuclear Dawson-derived sandwich compound [Cd4(H2O)2(As2W15O56)2]16- on 4-aminobenzoic acid modified glassy carbon electrode

International Nuclear Information System (INIS)

Bi Lihua; Shen Yan; Jiang Junguang; Wang Erkang; Dong Shaojun

2005-01-01

The transition metal-substituted heteropolyoxoanion, Cd 4 (H 2 O) 2 (As 2 W 15 O 56 ) 2 12- (As 4 W 30 Cd 4 ), is one of the trivacant Dawson derivatives. Its redox electrochemistry has been studied in acid buffer solutions using cyclic voltammetry. It exhibited three steps of four-electron redox waves attributed to redox processes of the tungsten-oxo framework. Through layer-by-layer assembly, the compound was first successfully immobilized on a 4-aminobenzoic acid modified glassy carbon electrode surface by alternate deposition with a quaternized poly(4-vinylpyridine) partially complexed with [Os(bpy) 2 Cl] 2+/+ (denoted as QPVP-Os). Thus, prepared multilayer films have been characterized by cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy (UV-vis). The electrocatalytic activities of the multilayer films containing As 4 W 30 Cd 4 have been investigated on the reduction of three substrates of important analytical interests, NO 2 - , BrO 3 - and IO 3 - . And with the increase of the number of As 4 W 30 Cd 4 layers, the catalytic current towards the reduction of BrO 3 - was enhanced and the catalytic potential shifted positively

Improved performance of solution-processed a-InGaZnO thin-film transistors due to Ar/O2 mixed-plasma treatment

International Nuclear Information System (INIS)

Kim, Kwan-Soo; Hwang, Yeong-Hyeon; Hwang, In-Chan; Cho, Won-Ju

2014-01-01

We investigated the effects of Ar and O 2 treatment and of Ar/O 2 mixed plasma treatment on the electrical characteristics of solution-processed amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The electrical performance and the instability of a-IGZO TFTs were significantly improved by the plasma treatments. The plasma treatments reduced the carbon-based residual contamination that acted as possible trap sites. In particular, the O 2 -plasma treatment produced a significant improvement in the reliability of a-IGZO TFTs when compared with the Ar-plasma-treated device, owing to the elimination of residual carbon in the active channel of the solution-processed a-IGZO. However, the optimized improvement of the solution-processed a-IGZO TFT under a gate bias stress was obtained for the device treated with an Ar/O 2 mixed-gas plasma. The plasma treatment in the Ar/O 2 -mixed ambience remarkably enhanced not only the reliability but also the electrical performance of the a-IGZO TFT; the on/off-current ratio, the field-effect mobility, and the subthreshold slope were 6.78 x 10 7 , 1.24 cm 2 /V·s, and 513 mV/dec, respectively.

Thin film fabrication and transport properties of the heavy Fermion oxide LiV{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Niemann, Ulrike [Max Planck Institute for Solid State Research, Stuttgart (Germany); Hirai, Daigorou [University of Tokyo, Tokyo (Japan); Takagi, Hidenori [Max Planck Institute for Solid State Research, Stuttgart (Germany); University of Tokyo, Tokyo (Japan); Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Stuttgart (Germany)

2016-07-01

The spinel compound LiV{sub 2}O{sub 4} is well-known for its heavy fermion behaviour, although it contains no f-electron bands. This unexpected behaviour has been a subject of several studies, but the origin of it is still not fully understood. In this study, we successfully fabricated single crystalline epitaxial thin film of LiV{sub 2}O{sub 4} on SrTiO{sub 3}, LSAT and MgO substrates, using a pulsed laser deposition technique. By changing film thickness and substrate materials, dimensionality and epitaxial strain was controlled. The formation of an epitaxially grown LiV{sub 2}O{sub 4} phase has been confirmed by X-ray diffraction measurements. LiV{sub 2}O{sub 4} films on MgO were found to be strained, due to the small lattice mismatch, in contrast to fully relaxed films on SrTiO{sub 3}.The heavy fermion behaviour of bulk LiV{sub 2}O{sub 4} at low temperatures is well reproduced in thick enough (∼ 7 nm) films on SrTiO{sub 3} substrates. In contrast, an insulating phase was found in strained LiV{sub 2}O{sub 4} thin films on MgO substrates, revealing the key role of the lattice in stabilising the metallic ground state. In this presentation, we discuss the thin film fabrication and the effect of epitaxial strain on heavy fermion behaviour in LiV{sub 2}O{sub 4}.

Solute activity coefficients in dilute aqueous electrolyte mixutes. III. The ternary system HCLO4 + UO2(CLO4)2 + H2O at 250C

International Nuclear Information System (INIS)

Boyd, G.E.

1977-01-01

Isopiestic vapor pressure comparison measurements were conducted with the three-component system HClO 4 + UO 2 (ClO 4 ) 2 + H 2 O in the concentration range between I = 0.05 and 1.9 m. Analysis of the mixture composition and concentration dependence of the osmotic coefficients with the Scatchard neutral-electrolyte and ion-component methods and with the Pitzer ion-component methods gave equally satisfactory results. Prediction of the observed osmotic coefficients by two-component approximations was satisfactory, and the data agreed well with values estimated with a model based on the osmolal fraction. A fair concordance was also found between predicted solute activity coefficients from simple models and values derived from complete treatments which included interaction terms

A photochemical proposal for the preparation of ZnAl{sub 2}O{sub 4} and MgAl{sub 2}O{sub 4} thin films from β-diketonate complex precursors

Energy Technology Data Exchange (ETDEWEB)

Cabello, G., E-mail: gerardocabelloguzman@hotmail.com [Departamento de Ciencias Básicas, Facultad de Ciencias, Universidad del Bío-Bío, Chillán (Chile); Lillo, L.; Caro, C.; Seguel, M.; Sandoval, C. [Departamento de Ciencias Básicas, Facultad de Ciencias, Universidad del Bío-Bío, Chillán (Chile); Buono-Core, G.E. [Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso (Chile); Chornik, B.; Flores, M. [Deparamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago 8370415 (Chile)

2016-05-15

Highlights: • ZnAl{sub 2}O{sub 4} and MgAl{sub 2}O{sub 4} thin films were prepared by photo-chemical method. • The Zn(II), Mg(II) and Al(III) β-diketonate complexes were used as precursors. • The photochemical reaction was monitored by UV–vis and FT-IR spectroscopy. • The results reveal spinel oxide formation and the generation of intermediate products. - Abstract: ZnAl{sub 2}O{sub 4} and MgAl{sub 2}O{sub 4} thin films were grown on Si(100) and quartz plate substrates using a photochemical method in the solid phase with thin films of β-diketonate complexes as the precursors. The films were deposited by spin-coating and subsequently photolyzed at room temperature using 254 nm UV light. The photolysis of these films results in the deposition of metal oxide thin films and fragmentation of the ligands from the coordination sphere of the complexes. The obtained samples were post-annealed at different temperatures (350–1100 °C) for 2 h and characterized by FT-Infrared spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force miscroscopy (AFM), and UV–vis spectroscopy. The results indicate the formation of spinel-type structures and other phases. These characteristics determined the quality of the films, which were obtained from the photodeposition of ternary metal oxides.

Optical Properties and Surface Morphology of Nano-composite PMMA: TiO2 Thin Films

International Nuclear Information System (INIS)

Lyly Nyl Ismail; Ahmad Fairoz Aziz; Habibah Zulkefle

2011-01-01

There are two nano-composite PMMA: TiO 2 solutions were prepared in this research. First solution is nano-composite PMMA commercially available TiO 2 nanopowder and the second solution is nano-composite PMMA with self-prepared TiO 2 powder. The self-prepared TiO 2 powder is obtained by preparing the TiO 2 sol-gel. Solvo thermal method were used to dry the TiO 2 sol-gel and obtained TiO 2 crystal. Ball millers were used to grind the TiO 2 crystal in order to obtained nano sized powder. Triton-X was used as surfactant to stabilizer the composite between PMMA: TiO 2 . Besides comparing the nano-composite solution, we also studied the effect of the thin films thickness on the optical properties and surface morphology of the thin films. The thin films were deposited by sol-gel spin coating method on glass substrates. The optical properties and surface characterization were measured with UV-VIS spectrometer equipment and atomic force microscopy (AFM). The result showed that nano-composite PMMA with self prepared TiO 2 give high optical transparency than nano-composite PMMA with commercially available TiO 2 nano powder. The results also indicate as the thickness is increased the optical transparency are decreased. Both AFM images showed that the agglomerations of TiO 2 particles are occurred on the thin films and the surface roughness is increased when the thickness is increased. High agglomeration particles exist in the AFM images for nano-composite PMMA: TiO 2 with TiO 2 nano powder compare to the other nano-composite solution. (author)

Epitaxial integration of CoFe2O4 thin films on Si (001) surfaces using TiN buffer layers

Science.gov (United States)

Prieto, Pilar; Marco, José F.; Prieto, José E.; Ruiz-Gomez, Sandra; Perez, Lucas; del Real, Rafael P.; Vázquez, Manuel; de la Figuera, Juan

2018-04-01

Epitaxial cobalt ferrite thin films with strong in-plane magnetic anisotropy have been grown on Si (001) substrates using a TiN buffer layer. The epitaxial films have been grown by ion beam sputtering using either metallic, CoFe2, or ceramic, CoFe2O4, targets. X-ray diffraction (XRD) and Rutherford spectrometry (RBS) in random and channeling configuration have been used to determine the epitaxial relationship CoFe2O4 [100]/TiN [100]/Si [100]. Mössbauer spectroscopy, in combination with XRD and RBS, has been used to determine the composition and structure of the cobalt ferrite thin films. The TiN buffer layer induces a compressive strain in the cobalt ferrite thin films giving rise to an in-plane magnetic anisotropy. The degree of in-plane anisotropy depends on the lattice mismatch between CoFe2O4 and TiN, which is larger for CoFe2O4 thin films grown on the reactive sputtering process with ceramic targets.

Electrodeposition of In{sub 2}O{sub 3} thin films from a dimethylsulfoxide based electrolytic solution

Energy Technology Data Exchange (ETDEWEB)

Henriquez, R.; Munoz, E.; Gomez, H. [Instituto de Quimica, Facultad de Ciencias, Pontificia Universidad Catolica de Valparaiso, Curauma Valparaiso (Chile); Dalchiele, E.A.; Marotti, R.E. [Instituto de Fisica and CINQUIFIMA, Facultad de Ingenieria, Montevideo (Uruguay); Martin, F.; Leinen, D.; Ramos-Barrado, J.R. [Laboratorio de Materiales y Superficie, Departamento de Fisica Aplicada and Ingenieria Quimica, Universidad de Malaga (Spain)

2013-02-15

Indium (III) oxide (In{sub 2}O{sub 3}) thin films have been obtained after heat treatment of In(OH){sub 3} precursor layers grown by a potential cycling electrodeposition (PCED) method from a dimethylsulfoxide (DMSO) based electrolytic solution onto fluorine-doped tin oxide (FTO) coated glass substrates. X-ray diffraction (XRD) measurements indicate the formation of a polycrystalline In{sub 2}O{sub 3} phase with a cubic structure. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed a smooth morphology of the In{sub 2}O{sub 3} thin films after an optimized heat treatment had been developed. The surface composition and chemical state of the semiconductor films was established by X-ray photoelectron spectroscopy analysis. The nature of the semiconductor material, flat band potential and donor density were determined from Mott-Schottky plots. This study reveals that the In{sub 2}O{sub 3} films exhibited n-type conductivity with an average donor density of 2.2 x 10{sup 17} cm{sup -3}. The optical characteristics were determined through transmittance spectra. The direct and indirect band gap values obtained are according to the accepted values for the In{sub 2}O{sub 3} films of 2.83 and 3.54 eV for the indirect and direct band gap values. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

TiO2 thin-films on polymer substrates and their photocatalytic activity

International Nuclear Information System (INIS)

Yang, Jae-Hun; Han, Yang-Su; Choy, Jin-Ho

2006-01-01

We have developed dip-coating process for TiO 2 -thin film on polymer substrates (acrylonitrile-butadiene-styrene polymer: ABS, polystyrene: PS). At first, a monodispersed and transparent TiO 2 nano-sol solution was prepared by the controlled hydrolysis of titanium iso-propoxide in the presence of acetylacetone and nitric acid catalyst at 80 deg. C. Powder X-ray diffraction patterns of the dried particles are indicative of crystalline TiO 2 with anatase-type structure. According to the XRD and transmission electron microscopy (TEM) studies, the mean particle size was estimated to be ca. 5 nm. The transparent thin films on ABS and PS substrates were fabricated by dip-coating process by changing the processing variables, such as the number of dip-coating and TiO 2 concentration in nano-sol solution. Scanning electron microscopic (SEM) analysis for the thin film samples reveals that the acetylacetone-modified TiO 2 nano-sol particles are effective for enhancing the interfacial adherence between films and polymeric substrates compared to the unmodified one. Photocatalytic degradation of methylene blue (MB) on the TiO 2 thin-films has also been systematically investigated

Solution derived ZnO:Al films with low resistivity

International Nuclear Information System (INIS)

Schellens, K.; Capon, B.; De Dobbelaere, C.; Detavernier, C.; Hardy, A.; Van Bael, M.K.

2012-01-01

ZnO:Al thin films were prepared via chemical solution deposition, using 2-butoxyethanol as an alternative for 2-methoxyethanol, which is more commonly used, but acutely toxic. The precursor solutions can be readily spin coated. The phase, morphology, electrical and optical properties of the deposited films are investigated, by XRD (X-ray diffraction), scanning electron microscopy, a two-point contact measurement and UV–vis spectrophotometry respectively. This way, the effect of this solvent is investigated. The films are deposited on borosilicate glass substrates and were found to be continuous and smooth. XRD measurements show a highly preferential c-axis orientation. The effects of the thermal treatment profile and Al dopant concentration are studied with respect to the obtained electrical properties. Optimally, the electrical resistivity was lowered to 6.5 × 10 −3 Ω cm after annealing at 450 °C in a 95% He/5% H 2 atmosphere. - Highlights: ► 2-Butoxyethanol as alternative for 2-methoxyethanol for precursor synthesis. ► Al:ZnO thin films with a strong preferential c-axis orientation are obtained. ► A forming gas anneal greatly improves the electrical properties. ► The addition of 1 at.% Al is found to improve the electrical properties.

Electric conduction mechanism of some heterocyclic compounds, 4,4′-bipyridine and indolizine derivatives in thin films

Energy Technology Data Exchange (ETDEWEB)

Danac, Ramona, E-mail: rdanac@uaic.ro [Faculty of Chemistry, Alexandru Ioan Cuza University of Iasi, Bulevardul Carol I, Nr. 11, 700506 Iasi (Romania); Leontie, Liviu, E-mail: lleontie@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bulevardul Carol I, Nr. 11, 700506 Iasi (Romania); Carlescu, Aurelian, E-mail: carlescu_aurelian@yahoo.com [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bulevardul Carol I, Nr. 11, 700506 Iasi (Romania); Shova, Sergiu, E-mail: shova@icmpp.ro [Petru Poni Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda, Nr. 41A, 700487 Iasi (Romania); Tiron, Vasile, E-mail: vasile.tiron@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bulevardul Carol I, Nr. 11, 700506 Iasi (Romania); Rusu, George G., E-mail: rusugxg@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bulevardul Carol I, Nr. 11, 700506 Iasi (Romania); Iacomi, Felicia, E-mail: iacomi@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bulevardul Carol I, Nr. 11, 700506 Iasi (Romania); Gurlui, Silviu, E-mail: sgurlui@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bulevardul Carol I, Nr. 11, 700506 Iasi (Romania); Șușu, Oana, E-mail: oasusu@gmail.com [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bulevardul Carol I, Nr. 11, 700506 Iasi (Romania); Rusu, Gheorghe I., E-mail: girusu@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bulevardul Carol I, Nr. 11, 700506 Iasi (Romania)

2016-08-01

Temperature dependence of d. c. electric conductivity of some recently synthesized heterocyclic compounds, 4,4′-bipyridine and indolizine derivatives, in thin films (d = 0.27–0.51 μm) spin-coated from chloroform solutions onto glass, is studied. The investigated compounds are polycrystalline (as shown by X-ray Diffraction analysis) and show typical n-type semiconductor behavior. The activation energy of d. c. electric conduction ranges between 1.55 and 2.33 eV. Some correlations between semiconducting characteristics and essential features of molecular structure of organic compounds have been established. In the higher temperature range (400–520 K), the electronic transport properties in present compounds can be explained in the frame of band gap representation model, while in the lower temperature range (300–350 K), the Mott's variable-range hopping conduction model can be conveniently used. - Highlights: • 4,4′-bipyridine and indolizine derivatives in thin films behave as n-type semiconductors. • The electron transfer is favored by extended conjugation and packing capacity. • The band gap representation is suitable in the higher temperature range. • The Mott's VRH conduction model may be used in the lower temperature range.

Electrochemical behavior of nanostructured MnO2/C (Vulcan® composite in aqueous electrolyte LiNO3

Directory of Open Access Journals (Sweden)

Vujković Milica

2011-01-01

Full Text Available The electrolytic solutions of contemporary Li-ion batteries are made exclusively with the organic solvents since anodic materials of these batteries have potentials with greater negativity than the potential of the water reduction, thus the organic electrolytes can withstand the voltages of 3-5 V that are characteristic for these batteries. Ever since it was discovered that some materials can electrochemically intercalate and deintercalate Li+ ions in aqueous solutions, numerous studies have been conducted with the aim of extending operational time of the aqueous Li-ion batteries. Manganese oxide has been studied as the electrode material in rechargeable lithium-ion batteries with organic electrolytes. In this paper its electrochemical behavior as an anode material in aqueous electrolyte solutions was examined. MnO2 as a component of nanodispersed MnO2/C (Vulcan® composite was successfully synthesized hydrothermally. Electrochemical properties of this material were investigated in aqueous saturated LiNO3 solution by both cyclic voltammetry and galvanostatic charging/discharging (LiMn2O4 as cathode material techniques. The obtained composite shows a relatively good initial discharge capacity of 96.5 mAh/g which, after 50th charging/discharging cycles, drops to the value of 57mAh/g. MnO2/C (Vulcan® composite, in combination with LiMn2O4 as a cathode material, shows better discharge capacity compared to other anodic materials used in aqueous Li-ion batteries according to certain studies that have been conducted. Its good reversibility and cyclability, and the fact that hydrothermal method is simple and effective, makes MnO2/C(Vulcan® composite a promising anodic material for aqueous Li-ion batteries.

New Method for Fabrication of Co3O4 Thin Film Sensors: Structural, Morphological and Optoelectronic Properties

Directory of Open Access Journals (Sweden)

Vikas PATIL

2011-05-01

Full Text Available Nanocrystalline Co3O4 thin films have been deposited by spin coating technique and then have been analyzed to test their application in NH3 gas-sensing technology. In particular, spectrophotometric and conductivity measurements have been performed in order to determine the optical and electrical properties of Co3O4 thin films. The structure and the morphology of such material have been investigated by X ray diffraction and Scanning electron microscopy. The X-ray diffraction studies confirmed that the films grown by this technique have good crystalline cubic spinel structure and present a random orientation. The morphology of the sol gel derived Co3O4 shows nanocrystalline grains with some overgrown clusters .The optical band gap has been determined from the absorption coefficient. We found that the optical band gap energy decreases from 2.58 eV to 2.07 eV with increasing annealing temperature between 400-700 oC. These mean that the optical quality of Co3O4 films is improved by annealing. The dc electrical conductivity of Co3O4 thin films were increased from 10-4 to 10-2(Ω cm-1 with increase in annealing temperature. The electron carrier concentration (n and mobility (μ of Co3O4 films annealed at 400-700 oC were estimated to be of the order of 2.4 to 4.5 x 1019 cm-3 and 5.2 to 7.0 x 10-5 cm2 V-1 s-1 respectively. It is observed that Co3O4 thin film annealing at 700 oC after deposition provide a smooth and flat texture suited for optoelectronic applications. Gas sensing properties showed that the Co3O4 films (at 700 oC were sensitive as well as fast in responding to NH3. A high sensitivity for ammonia indicates that the Co3O4 films are selective for this gas.

Preparation and properties of KCl-doped Cu{sub 2}O thin film by electrodeposition

Energy Technology Data Exchange (ETDEWEB)

Yu, Xiaojiao, E-mail: yxjw@xaut.edu.cn [Xi’an University of Technology, Xi’an 710048 (China); Li, Xinming [Xi’an University of Technology, Xi’an 710048 (China); Zheng, Gang [Xi’an University of Technology, Xi’an 710048 (China); Northwestern Polytechnical University, Xi’an 710072 (China); Wei, Yuchen [The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Zhang, Ama; Yao, Binghua [Xi’an University of Technology, Xi’an 710048 (China)

2013-04-01

With the indium tin oxide-coated glass as working electrode, cuprous oxide thin film is fabricated by means of electrodeposition. The effects of KCl doped and annealing treatment upon Cu{sub 2}O thin film morphology, surface resistivity, open-circuit voltage, electric conduction types and visible light response are studied. The research results indicate that KCl doped has a great effect upon Cu{sub 2}O crystal morphology, thus, making Cu{sub 2}O thin film surface resistivity drop, and the open-circuit voltage increase and that electric conduction types are transformed from p type into n type, and the visible light (400–500 nm) absorption rate is slightly reduced. Annealing treatment can obviously decrease Cu{sub 2}O thin film surface resistivity and improve its open-circuit voltage. When KCl concentration in electrolytic solution reaches 7 mmol/L, Cu{sub 2}O thin film morphology can be changed from the dendritic crystal into the cubic crystal and Cu{sub 2}O thin film surface resistivity decreases from the initial 2.5 × 10{sup 6} Ω cm to 8.5 × 10{sup 4} Ω cm. After annealing treatment at 320 °C for 30 min, the surface resistivity decreases to 8.5 × 10{sup 2} Ω cm, and the open-circuit voltage increases from the initial 3.1 mV to 79.2 mV.

New family of lanthanide-based inorganic-organic hybrid frameworks: Ln2(OH)4[O3S(CH2)nSO3]·2H2O (Ln = La, Ce, Pr, Nd, Sm; n = 3, 4) and their derivatives.

Science.gov (United States)

Liang, Jianbo; Ma, Renzhi; Ebina, Yasuo; Geng, Fengxia; Sasaki, Takayoshi

2013-02-18

We report the synthesis and structure characterization of a new family of lanthanide-based inorganic-organic hybrid frameworks, Ln(2)(OH)(4)[O(3)S(CH(2))(n)SO(3)]·2H(2)O (Ln = La, Ce, Pr, Nd, Sm; n = 3, 4), and their oxide derivatives. Highly crystallized samples were synthesized by homogeneous precipitation of Ln(3+) ions from a solution containing α,ω-organodisulfonate salts promoted by slow hydrolysis of hexamethylenetetramine. The crystal structure solved from powder X-ray diffraction data revealed that this material comprises two-dimensional cationic lanthanide hydroxide {[Ln(OH)(2)(H(2)O)](+)}(∞) layers, which are cross-linked by α,ω-organodisulfonate ligands into a three-dimensional pillared framework. This hybrid framework can be regarded as a derivative of UCl(3)-type Ln(OH)(3) involving penetration of organic chains into two {LnO(9)} polyhedra. Substitutional modification of the lanthanide coordination promotes a 2D arrangement of the {LnO(9)} polyhedra. A new hybrid oxide, Ln(2)O(2)[O(3)S(CH(2))(n)SO(3)], which is supposed to consist of alternating {[Ln(2)O(2)](2+)}(∞) layers and α,ω-organodisulfonate ligands, can be derived from the hydroxide form upon dehydration/dehydroxylation. These hybrid frameworks provide new opportunities to engineer the interlayer chemistry of layered structures and achieve advanced functionalities coupled with the advantages of lanthanide elements.

Thin film composites in the BiFeO3–Bi4Ti3O12 system obtained by an aqueous solution-gel deposition methodology

Directory of Open Access Journals (Sweden)

Carlos Gumiel

2018-01-01

Full Text Available Thin film multiferroic composites, with a high quantity of interfaces between the different materials, represent a more feasible alternative to single phase systems in which the multifunctional response is usually hampered due to intrinsic physical constraints. Nowadays some of these composites can be produced by applying deposition techniques such as PLD, CVD, MBE or the like, which allow a high degree of crystallographic control. However, despite their effectiveness, all these techniques also involve a high consumption of energy in terms of temperature and/or vacuum. Within this frame, the present contribution proposes a sustainable chemical solution deposition process to prepare thin films of the multiferroic BiFeO3–Bi4Ti3O12 composite system. More specifically an aqueous solution-gel plus spin-coating methodology is employed which also avoids the organic solvents typically used in a conventional sol–gel method, so further keeping an eye on the environmentally friendly conditions. Attempts are conducted that demonstrate how by systematically controlling the processing parameters it is possible to obtain thin film composites with a promising 3-3 type connectivity at temperatures as low as 600 °C.

Thin film composites in the BiFeO3–Bi4Ti3O12 system obtained by an aqueous solution-gel deposition methodology

International Nuclear Information System (INIS)

Gumiel, C.; Vranken, T.; Bernardo, M.S.; Jardiel, T.; Hardy, A.; Van Bael, M.K.; Peiteado, M.

2018-01-01

Thin film multiferroic composites, with a high quantity of interfaces between the different materials, represent a more feasible alternative to single phase systems in which the multifunctional response is usually hampered due to intrinsic physical constraints. Nowadays some of these composites can be produced by applying deposition techniques such as PLD, CVD, MBE or the like, which allow a high degree of crystallographic control. However, despite their effectiveness, all these techniques also involve a high consumption of energy in terms of temperature and/or vacuum. Within this frame, the present contribution proposes a sustainable chemical solution deposition process to prepare thin films of the multiferroic BiFeO3–Bi4Ti3O12 composite system. More specifically an aqueous solution-gel plus spin-coating methodology is employed which also avoids the organic solvents typically used in a conventional sol–gel method, so further keeping an eye on the environmentally friendly conditions. Attempts are conducted that demonstrate how by systematically controlling the processing parameters it is possible to obtain thin film composites with a promising 3-3 type connectivity at temperatures as low as 600°C. [es

Low-temperature fabrication of an HfO2 passivation layer for amorphous indium-gallium-zinc oxide thin film transistors using a solution process.

Science.gov (United States)

Hong, Seonghwan; Park, Sung Pyo; Kim, Yeong-Gyu; Kang, Byung Ha; Na, Jae Won; Kim, Hyun Jae

2017-11-24

We report low-temperature solution processing of hafnium oxide (HfO 2 ) passivation layers for amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). At 150 °C, the hafnium chloride (HfCl 4 ) precursor readily hydrolyzed in deionized (DI) water and transformed into an HfO 2 film. The fabricated HfO 2 passivation layer prevented any interaction between the back surface of an a-IGZO TFT and ambient gas. Moreover, diffused Hf 4+ in the back-channel layer of the a-IGZO TFT reduced the oxygen vacancy, which is the origin of the electrical instability in a-IGZO TFTs. Consequently, the a-IGZO TFT with the HfO 2 passivation layer exhibited improved stability, showing a decrease in the threshold voltage shift from 4.83 to 1.68 V under a positive bias stress test conducted over 10,000 s.

Photoluminescence properties of BaMoO4 amorphous thin films

International Nuclear Information System (INIS)

Marques, Ana Paula Azevedo; Melo, Dulce M.A. de; Longo, Elson; Paskocimas, Carlos A.; Pizani, Paulo S.; Leite, Edson R.

2005-01-01

BaMoO 4 amorphous and crystalline thin films were prepared from polymeric precursors. The BaMoO 4 was deposited onto Si wafers by means of the spinning technique. The structure and optical properties of the resulting films were characterized by FTIR reflectance spectra, X-ray diffraction (XRD), atomic force microscopy (AFM) and optical reflectance. The bond Mo-O present in BaMoO 4 was confirmed by FTIR reflectance spectra. XRD characterization showed that thin films heat-treated at 600 and 200 deg. C presented the scheelite-type crystalline phase and amorphous, respectively. AFM analyses showed a considerable variation in surface morphology by comparing samples heat-treated at 200 and 600 deg. C. The reflectivity spectra showed two bands, positioned at 3.38 and 4.37 eV that were attributed to the excitonic state of Ba 2+ and electronic transitions within MoO 2- 4 , respectively. The optical band gaps of BaMoO 4 were 3.38 and 2.19 eV, for crystalline (600 deg. C/2 h) and amorphous (200 deg. C/8 h) films, respectively. The room-temperature luminescence spectra revealed an intense single-emission band in the visible region. The PL intensity of these materials was increased upon heat-treatment. The excellent optical properties observed for BaMoO 4 amorphous thin films suggested that this material is a highly promising candidate for photoluminescent applications

Oriented growth of Sr n+1Ti n O3n+1 Ruddlesden-Popper phases in chemical solution deposited thin films

International Nuclear Information System (INIS)

Gutmann, Emanuel; Levin, Alexandr A.; Reibold, Marianne; Mueller, Jan; Paufler, Peter; Meyer, Dirk C.

2006-01-01

Oriented thin films of perovskite-related Sr n +1 Ti n O 3 n +1 Ruddlesden-Popper phases (n=1, 2, 3) were grown on (001) single-crystalline SrTiO 3 substrates. Preparation of the films was carried out by wet chemical deposition from metalorganic Sr-Ti solutions (rich in Sr) and subsequent conversion into the crystalline state by thermal treatment in air atmosphere at a maximum temperature of 700 deg. C. Solutions were prepared by a modified Pechini method. The films were investigated by wide-angle X-ray scattering and high-resolution transmission electron microscopy. The phase content of powders prepared from the dried solutions and annealed under similar conditions differed from that present in the films, i.e. only polycrystalline SrTiO 3 was detected together with oxides of Ti and Sr. - Graphical abstract: Cross-sectional image of an oriented chemical solution deposited thin film obtained by high-resolution transmission electron microscopy. Periodical spacings corresponding to SrTiO 3 substrate (right) and Sr 2 TiO 4 Ruddlesden-Popper phase (n=1) film region (left) are marked

Nanostructural origin of semiconductivity and large magnetoresistance in epitaxial NiCo2O4/Al2O3 thin films

Science.gov (United States)

Zhen, Congmian; Zhang, XiaoZhe; Wei, Wengang; Guo, Wenzhe; Pant, Ankit; Xu, Xiaoshan; Shen, Jian; Ma, Li; Hou, Denglu

2018-04-01

Despite low resistivity (~1 mΩ cm), metallic electrical transport has not been commonly observed in inverse spinel NiCo2O4, except in certain epitaxial thin films. Previous studies have stressed the effect of valence mixing and the degree of spinel inversion on the electrical conduction of NiCo2O4 films. In this work, we studied the effect of nanostructural disorder by comparing the NiCo2O4 epitaxial films grown on MgAl2O4 (1 1 1) and on Al2O3 (0 0 1) substrates. Although the optimal growth conditions are similar for the NiCo2O4 (1 1 1)/MgAl2O4 (1 1 1) and the NiCo2O4 (1 1 1)/Al2O3 (0 0 1) films, they show metallic and semiconducting electrical transport, respectively. Post-growth annealing decreases the resistivity of NiCo2O4 (1 1 1)/Al2O3 (0 0 1) films, but the annealed films are still semiconducting. While the semiconductivity and the large magnetoresistance in NiCo2O4 (1 1 1)/Al2O3 (0 0 1) films cannot be accounted for in terms of non-optimal valence mixing and spinel inversion, the presence of anti-phase boundaries between nano-sized crystallites, generated by the structural mismatch between NiCo2O4 and Al2O3, may explain all the experimental observations in this work. These results reveal nanostructural disorder as being another key factor for controlling the electrical transport of NiCo2O4, with potentially large magnetoresistance for spintronics applications.

Synthesis and electrochemical analysis of AlVMoO7 oxide prepared ...

Indian Academy of Sciences (India)

2018-05-16

May 16, 2018 ... solid solution and two-phase regimes. In the voltage ... LiMn2O4) [1]. Among these compounds, olivine LiFePO4, ... polyanions provide numerous metal oxidation states, struc- tural stability ... 2.1a Sol–gel synthesis (SG): In SG synthesis method, ... AlVMoO7 and confirms that only a single phase is formed.

Development of thin film cathodes for lithium-ion batteries in the material system Li–Mn–O by r.f. magnetron sputtering

International Nuclear Information System (INIS)

Fischer, J.; Adelhelm, C.; Bergfeldt, T.; Chang, K.; Ziebert, C.; Leiste, H.; Stüber, M.; Ulrich, S.; Music, D.; Hallstedt, B.; Seifert, H.J.

2013-01-01

Today most commercially available lithium ion batteries are still based on the toxic and expensive LiCoO 2 as a standard cathode material. However, lithium manganese based cathode materials are cheaper and environmentally friendlier. In this work cubic-LiMn 2 O 4 spinel, monoclinic-Li 2 MnO 3 and orthorhombic-LiMnO 2 thin films have been synthesized by non-reactive r.f. magnetron sputtering from two ceramic targets (LiMn 2 O 4 , LiMnO 2 ) in a pure argon discharge. The deposition parameters, namely target power and working gas pressure, were optimized in a combination with a post deposition heat treatment with respect to microstructure and electrochemical behavior. The chemical composition was determined using inductively coupled plasma optical emission spectroscopy and carrier gas hot extraction. The films' crystal structure, phase evolution and morphology were investigated by X-ray diffraction, micro Raman spectroscopy and scanning electron microscopy. Due to the fact that these thin films consist of the pure active material without any impurities, such as binders or conductive additives like carbon black, they are particularly well suited for measurements of the intrinsic physical properties, which is essential for fundamental understanding. The electrochemical behavior of the cubic and the orthorhombic films was investigated by galvanostatic cycling in half cells against metallic lithium. The cubic spinel films exhibit a maximum specific capacity of ∼ 82 mAh/g, while a specific capacity of nearly 150 mAh/g can be reached for the orthorhombic counterparts. These films are promising candidates for future all solid state battery applications. - Highlights: ► Synthesis of 3 Li–Mn–O structures by one up-scalable thin film deposition method ► Formation of o-LiMnO 2 by r.f. magnetron sputtering in combination with post-annealing ► Discharge capacity with o-LiMnO 2 cathodes twice as high as for c-LiMn 2 O 4 ► Thin film deposition of m-Li 2 MnO 3 and

Magnetic and transport properties of Zn0.4Fe2.6O4 thin films with highly preferential orientation

International Nuclear Information System (INIS)

Lu, Z.L.; Zou, W.Q.; Liu, X.C.; Lin, Y.B.; Lu, Z.H.; Wang, J.F.; Xu, J.P.; Lv, L.Y.; Zhang, F.M.; Du, Y.W.

2007-01-01

Highly preferentially oriented Zn 0.4 Fe 2.6 O 4 thin films have been fabricated on Si, SrTiO 3 and ZrO 2 substrates, respectively, using RF magnetron sputtering. All the films show a large saturation magnetization of about 4.2μ B and low coercive field at 300 K and a spin (cluster) glass transition at about 60 K due to the non-magnetic Zn 2+ ions substitution. Moreover, the fairly high spin polarization of the carrier at 300 K has been confirmed by both the giant magnetoresistance and anomalous Hall coefficient measurements

Solution derived ZnO:Al films with low resistivity

Energy Technology Data Exchange (ETDEWEB)

Schellens, K. [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan, Building D, 3590 Diepenbeek (Belgium); Capon, B. [Ghent University, Department of Solid State Sciences, Krijgslaan 281/S1, 9000 Ghent (Belgium); IMEC and SIM program SoPPoM, Kapeldreef 75, 3001 Leuven (Belgium); De Dobbelaere, C. [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan, Building D, 3590 Diepenbeek (Belgium); Detavernier, C. [Ghent University, Department of Solid State Sciences, Krijgslaan 281/S1, 9000 Ghent (Belgium); IMEC and SIM program SoPPoM, Kapeldreef 75, 3001 Leuven (Belgium); Hardy, A. [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan, Building D, 3590 Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Institute for Materials Research, Wetenschapspark 1, 3590 Diepenbeek (Belgium); IMEC and SIM program SoPPoM, Kapeldreef 75, 3001 Leuven (Belgium); Van Bael, M.K., E-mail: marlies.vanbael@uhasselt.be [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan, Building D, 3590 Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Institute for Materials Research, Wetenschapspark 1, 3590 Diepenbeek (Belgium); IMEC and SIM program SoPPoM, Kapeldreef 75, 3001 Leuven (Belgium)

2012-12-01

ZnO:Al thin films were prepared via chemical solution deposition, using 2-butoxyethanol as an alternative for 2-methoxyethanol, which is more commonly used, but acutely toxic. The precursor solutions can be readily spin coated. The phase, morphology, electrical and optical properties of the deposited films are investigated, by XRD (X-ray diffraction), scanning electron microscopy, a two-point contact measurement and UV-vis spectrophotometry respectively. This way, the effect of this solvent is investigated. The films are deposited on borosilicate glass substrates and were found to be continuous and smooth. XRD measurements show a highly preferential c-axis orientation. The effects of the thermal treatment profile and Al dopant concentration are studied with respect to the obtained electrical properties. Optimally, the electrical resistivity was lowered to 6.5 Multiplication-Sign 10{sup -3} {Omega} cm after annealing at 450 Degree-Sign C in a 95% He/5% H{sub 2} atmosphere. - Highlights: Black-Right-Pointing-Pointer 2-Butoxyethanol as alternative for 2-methoxyethanol for precursor synthesis. Black-Right-Pointing-Pointer Al:ZnO thin films with a strong preferential c-axis orientation are obtained. Black-Right-Pointing-Pointer A forming gas anneal greatly improves the electrical properties. Black-Right-Pointing-Pointer The addition of 1 at.% Al is found to improve the electrical properties.

Facile synthesis of LiAl0.1Mn1.9O4 as cathode material for lithium ion batteries: towards rate and cycling capabilities at an elevated temperature

International Nuclear Information System (INIS)

Guo, Donglei; Li, Bao; Chang, Zhaorong; Tang, Hongwei; Xu, Xinhong; Chang, Kun; Shangguan, Enbao; Yuan, Xiao-Zi; Wang, Haijiang

2014-01-01

To improve the cycling performance of spinel LiMn 2 O 4 , Al-doped LiMn 2 O 4 , LiAl 0.1 Mn 1.9 O 4 , is synthesized using Mn 1.9 Al 0.1 O 3 precursor and LiOH·H 2 O via a low temperature solid-phase reaction. The Mn 1.9 Al 0.1 O 3 precursor, prepared from the electrolytic manganese dioxide (EMD) and Al(OH) 3 , is composed of spherical particles with an average diameter of 300 nm, and has a large interspace. Energy dispersive spectrometer (EDS) indicates the Al element is well distributed in Mn 1.9 Al 0.1 O 3 and LiAl 0.1 Mn 1.9 O 4 . The scanning electron microscopy (SEM) and transmission electron microscope (TEM) images show that the LiAl 0.1 Mn 1.9 O 4 sample has a high crystallinity with sizes ranging from 300 to 500 nm. Electrochemical properties of LiAl 0.1 Mn 1.9 O 4 are studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge. The results show that LiAl 0.1 Mn 1.9 O 4 possesses better rate and cycling capabilities than LiMn 2 O 4 at both 25 °C and 55 °C. At a rate of 5 C, the capacity retention ratio of the LiMn 1.9 Al 0.1 O 4 electrode after 100 cycles is about 95% at 25 °C and about 90% at 55 °C

Growth and in-plane magnetic anisotropy of inverse spinel Co{sub 2}MnO{sub 4} thin films

Energy Technology Data Exchange (ETDEWEB)

Koo, Taeyeong; Kim, Jaeyeong [Pohang University of Science and Technology, Pohang (Korea, Republic of); Song, Jonghyun [Chungnam National University, Daejeon (Korea, Republic of)

2014-11-15

Epitaxial Co{sub 2}MnO{sub 4} thin films were grown on Nb(0.1wt.)-doped SrTiO{sub 3} single-crystal substrates with (100) and (110) crystal orientations by using pulsed laser deposition. Their crystal structures and magnetic properties were investigated. Both samples exhibited ferrimagnetic transitions with enhanced transition temperatures. Isotropic M-H loops were observed on the in-plane surface of Co{sub 2}MnO{sub 4}(00l) grown on Nb(0.1wt)-doped SrTiO{sub 3}(100). Strong magnetic anisotropy was observed on the in-plane surface for Co{sub 2}MnO{sub 4} (ll0) grown on Nb(0.1wt)-doped SrTiO{sub 3}(110). A magnetic easy axis existed along the elongated tetragonal direction. This was attributed to the strong interplay between the spin and lattice degrees of freedom in the Co{sub 2}MnO{sub 4} thin film.

Synthesis of Cu2ZnSnS4 thin films by a precursor solution paste for thin film solar cell applications.

Science.gov (United States)

Cho, Jin Woo; Ismail, Agus; Park, Se Jin; Kim, Woong; Yoon, Sungho; Min, Byoung Koun

2013-05-22

Cu2ZnSnS4 (CZTS) is a very promising semiconductor material when used for the absorber layer of thin film solar cells because it consists of only abundant and inexpensive elements. In addition, a low-cost solution process is applicable to the preparation of CZTS absorber films, which reduces the cost when this film is used for the production of thin film solar cells. To fabricate solution-processed CZTS thin film using an easily scalable and relatively safe method, we suggest a precursor solution paste coating method with a two-step heating process (oxidation and sulfurization). The synthesized CZTS film was observed to be composed of grains of a size of ~300 nm, showing an overall densely packed morphology with some pores and voids. A solar cell device with this film as an absorber layer showed the highest efficiency of 3.02% with an open circuit voltage of 556 mV, a short current density of 13.5 mA/cm(2), and a fill factor of 40.3%. We also noted the existence of Cd moieties and an inhomogeneous Zn distribution in the CZTS film, which may have been triggered by the presence of pores and voids in the CZTS film.

Single-crystalline MgAl2O4 spinel nanotubes using a reactive and removable MgO nanowire template

International Nuclear Information System (INIS)

Fan Hongjin; Knez, Mato; Scholz, Roland; Nielsch, Kornelius; Pippel, Eckhard; Hesse, Dietrich; Goesele, Ulrich; Zacharias, Margit

2006-01-01

Using MgO nanowires as a reactive template, we fabricated for the first time single-crystal MgAl 2 O 4 spinel nanotubes through an interfacial solid-state reaction of MgO-Al 2 O 3 core-shell nanowires. Single-crystal MgO nanowires are coated with a conformal thin layer of amorphous Al 2 O 3 via atomic layer deposition. Subsequent annealing at 700 deg. C activates the interfacial reaction between MgO and Al 2 O 3 , transforming the alumina shell into a spinel shell. Finally, after etching away the remaining MgO core in ammonia sulfuric solution, MgAl 2 O 4 spinel nanotubes are obtained. As a transition from conventional planar spinel layers via thin-film interface reactions, our result might open a window for the fabrication of a wide variety of MgO-based spinel one-dimensional nanostructures

Improved performance of solution-processed a-InGaZnO thin-film transistors due to Ar/O{sub 2} mixed-plasma treatment

Energy Technology Data Exchange (ETDEWEB)

Kim, Kwan-Soo; Hwang, Yeong-Hyeon; Hwang, In-Chan; Cho, Won-Ju [Kwangwoon University, Seoul (Korea, Republic of)

2014-08-15

We investigated the effects of Ar and O{sub 2} treatment and of Ar/O{sub 2} mixed plasma treatment on the electrical characteristics of solution-processed amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The electrical performance and the instability of a-IGZO TFTs were significantly improved by the plasma treatments. The plasma treatments reduced the carbon-based residual contamination that acted as possible trap sites. In particular, the O{sub 2}-plasma treatment produced a significant improvement in the reliability of a-IGZO TFTs when compared with the Ar-plasma-treated device, owing to the elimination of residual carbon in the active channel of the solution-processed a-IGZO. However, the optimized improvement of the solution-processed a-IGZO TFT under a gate bias stress was obtained for the device treated with an Ar/O{sub 2} mixed-gas plasma. The plasma treatment in the Ar/O{sub 2}-mixed ambience remarkably enhanced not only the reliability but also the electrical performance of the a-IGZO TFT; the on/off-current ratio, the field-effect mobility, and the subthreshold slope were 6.78 x 10{sup 7}, 1.24 cm{sup 2}/V·s, and 513 mV/dec, respectively.

Synthesis of ZnFe2O4/SiO2 composites derived from a diatomite template.

Science.gov (United States)

Liu, Zhaoting; Fan, Tongxiang; Zhou, Han; Zhang, Di; Gong, Xiaolu; Guo, Qixin; Ogawa, Hiroshi

2007-03-01

A novel porous ZnFe2O4/SiO2 composite product has been generated with a template-directed assembly method from porous diatomite under different synthesis conditions, such as precursor concentrations (metallic nitrates), calcination temperature and diatomite type. The phase composition and morphology of all the materials were examined by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The results indicated that an inherited hierarchical porous structure from the diatomite template can be obtained, and the synthesis conditions were found to have clear effects on the formation of the ZnFe2O4/SiO2 composite. The ideal composite of ZnFe2O4/SiO2 can be obtained through optimization of diatomite template type, precursor solution and calcination temperature. Furthermore, the adsorption abilities of two types of diatomites were analyzed in detail using FTIR spectra and nitrogen adsorption measurements etc, which proved that A-diatomite (Shengzhou-diatomite) is better than B-diatomite (Changbai-diatomite) on the aspect of adsorbing Zn and Fe ions, and of forming the ZnFe2O4.

Growth and giant coercive field of spinel-structured Co3- x Mn x O4 thin films

Science.gov (United States)

Kwak, Yongsu; Song, Jonghyun; Koo, Taeyeong

2016-08-01

We grew epitaxial thin films of CoMn2O4 and Co2MnO4 on Nb-doped SrTiO3(011) and SrTiO3(001) single crystal substrates using pulsed laser deposition. The magnetic Curie temperature ( T c ) of the Co2MnO4 thin films was ~176 K, which is higher than that of the bulk whereas CoMn2O4 thin films exhibited a value of T c (~151 K) lower than that of the bulk. For the Co2MnO4 thin films, the M - H loop showed a coercive field of ~0.7 T at 10 K, similar to the value for the bulk. However, the M -H loop of the CoMn2O4(0 ll) thin film grown on a Nb-doped SrTiO3(011) substrate exhibited a coercive field of ~4.5 T at 30 K, which is significantly higher than those of the Co2MnO4 thin film and bulk. This giant coercive field, only observed for the CoMn2O4(0 ll) thin film, can be attributed to the shape anisotropy and strong spin-orbit coupling.

Improved performance of dye-sensitized solar cells: An TiO{sub 2}-nano-SiO{sub 2} hybrid photoanode with post-treatment of TiCl{sub 4} aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Liu Ling; Niu Haihong; Zhang Shouwei; Wan Lei [School of Electrical Engineering and Automation, Hefei University of Technology (HFUT), School of Chemical Engineering, HFUT, Hefei 230009 (China); Miao Shiding, E-mail: miaosd@iccas.ac.cn [School of Electrical Engineering and Automation, Hefei University of Technology (HFUT), School of Chemical Engineering, HFUT, Hefei 230009 (China); Xu Jinzhang, E-mail: xujz@hfut.edu.cn [School of Electrical Engineering and Automation, Hefei University of Technology (HFUT), School of Chemical Engineering, HFUT, Hefei 230009 (China)

2012-11-15

Highlights: Black-Right-Pointing-Pointer A TiO{sub 2}-nano-SiO{sub 2} hybrid film was prepared by depositing a paste of TiO{sub 2} (P{sub 25}) incorporated with SiO{sub 2}. Black-Right-Pointing-Pointer The optimal concentration of TiCl{sub 4} solution was found to be 75 mM for the post-treatment. Black-Right-Pointing-Pointer A photoelectron conversion efficiency of 6.39% was achieved for the prepared dye-sensitized solar cells (DSSCs). Black-Right-Pointing-Pointer SiO{sub 2} gives a significant improvement in the performance of the DSSCs. - Abstract: A TiO{sub 2}-nano-SiO{sub 2} hybrid film was prepared on a conductive F-doped tin oxide (FTO) substrate by depositing a mixture paste of TiO{sub 2} (P{sub 25}) and nano-sized SiO{sub 2} particles. The hybrid film was further treated by a titanium tetrachloride (TiCl{sub 4}) aqueous solution with different concentrations before it was assembled as a photoanode in dye sensitized solar cells (DSSCs). We studied the performance of DSSCs by using the dye molecule of cis-bis(isothiocy-anato)-bis-(2,2 Prime -bipyridyl-4,4 Prime -dicarboxylato) -ruthenium(II) bis-tetrabutylammonium (N719) as sensitizer. Results suggested that the post-treatment using TiCl{sub 4} could enhance the dye adsorption. The thin TiO{sub 2} layer hydrolyzed from TiCl{sub 4} could fill gaps between nanoparticles in the composite film, leading to a better electron transport than non-treated films, and improve the light harvesting efficiency. The optimal concentration was found to be 75 mM for the post-treatment of TiO{sub 2}-SiO{sub 2} hybrid film by TiCl{sub 4} solution. A photoelectron conversion efficiency of 6.39% was achieved in the back-side illuminated dye-sensitized solar cells, which is {approx}105% higher than the basic efficiency of the bare TiO{sub 2} sensitized sample. TiO{sub 2}-nano-SiO{sub 2} hybrid photoanode was prepared by incorporation of nano-sized SiO{sub 2} in the TiO{sub 2} film. The introduced SiO{sub 2} as a wide band

Microwave-assisted synthesis and characterization of poly(acrylic)/SiO2-TiO2 core-shell nanoparticle hybrid thin films

International Nuclear Information System (INIS)

Chien, Wen-Chen; Yu, Yang-Yen; Chen, Po-Kan; Yu, Hui-Huan

2011-01-01

In this study, poly(acrylic)/SiO 2 -TiO 2 core-shell nanoparticle hybrid thin films were successfully synthesized by microwave-assisted polymerization. The coupling agent 3-(trimethoxysilyl) propyl methacrylate (MSMA) was hydrolyzed with colloidal SiO 2 -TiO 2 core-shell nanoparticles, and then polymerized with two acrylic monomers and initiator to form a precursor solution. The results of this study showed that the spin-coated hybrid films had relatively good surface planarity, high thermal stability, a tunable refractive index (1.525 2 -TiO 2 core-shell nanoparticle hybrid thin films, for potential use in optical applications.

Liquid flow deposited spinel (Ni,Mn){sub 3}O{sub 4} thin films for microbolometer applications

Energy Technology Data Exchange (ETDEWEB)

Le, Duc Thang, E-mail: ducthang36@skku.edu [Intelligent Electronic Component Team, Electronic Materials Convergence Division, Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of); School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Jeon, Chang Jun; Lee, Kui Woong; Jeong, Young Hun; Yun, Ji Sun [Intelligent Electronic Component Team, Electronic Materials Convergence Division, Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of); Yoon, Dae Ho, E-mail: dhyoon@skku.edu [School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Cho, Jeong Ho, E-mail: goedc@kicet.re.kr [Intelligent Electronic Component Team, Electronic Materials Convergence Division, Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of)

2015-03-01

Highlights: • Highly quality (Ni,Mn){sub 3}O{sub 4} thin films were grown using liquid flow deposited (LFD) technique. • It is possible to deposit multi–component manganite–oxide thin films by LFD at low temperatures. • Nickel–manganite films showed a good negative temperature coefficient (NTC) characteristic. • Liquid flow deposited (Ni,Mn){sub 3}O{sub 4} thin films are very potential for microbolometer applications. - Abstract: A liquid flow deposition (LFD) technique was initially used for the fabrication of single-component Mn{sub 3}O{sub 4} thin films onto Si wafer substrates at a range of substrate temperatures of 30–80 °C, with the introduction of an oxidizing reagent (H{sub 2}O{sub 2}). As a result, solid thin films were well formed from an aqueous solution. An X-ray diffraction (XRD) analysis showed typical characteristics of hausmannite Mn{sub 3}O{sub 4} with a spinel tetragonal phase. Field-emission scanning electron microscopy (FE-SEM) observations revealed nano-sized grains arranged uniformly on a dense and smooth surface for all of the as-deposited films. On the other hand, the LFD method was then extended to prepare two-component nickel–manganite films according to the binary chemical composition of Ni{sub x}Mn{sub 3−x}O{sub 4} with x = 0.02–0.2. The as-grown nickel–manganite films showed a surface with a good quality with a spherical bead-like architecture when x ≤ 0.10, while a conversion from spherical grains into highly porous nanowalls in the microstructure was noted in films when x ≥ 0.12. These results signify that it is possible to fabricate various multi-component manganite-oxide thin films at a low temperature. In addition, the dependences of the room-temperature electrical resistivity (ρ) and the temperature coefficient of resistance (TCR) on the Ni substitution level (x) were investigated on films annealed at 400 °C.

Ca{sub 2−x}Li{sub 2x}GeO{sub 4} solid solutions. Chemical composition range and flux crystal growth

Energy Technology Data Exchange (ETDEWEB)

Ivanov, V.A. [N.I. Lobachevsky State University of Nizhni Novgorod, Nizhni Novgorod, 603950 (Russian Federation); Marychev, M.O., E-mail: marychev@yandex.ru [N.I. Lobachevsky State University of Nizhni Novgorod, Nizhni Novgorod, 603950 (Russian Federation); Andreev, P.V.; Lykov, V.A.; Faddeev, M.A. [N.I. Lobachevsky State University of Nizhni Novgorod, Nizhni Novgorod, 603950 (Russian Federation); Koseva, I. [Bulgarian Academy of Science, Institute of General and Inorganic Chemistry, BU-1113 Sofia (Bulgaria); Nikolov, V. [N.I. Lobachevsky State University of Nizhni Novgorod, Nizhni Novgorod, 603950 (Russian Federation)

2015-11-01

A series of Ca{sub 2−x}Li{sub 2x}GeO{sub 4} specimens with 0 < 2x < 2, were synthesized by the classical solid state method. X-ray analysis revealed that for 0 < 2x < 0.6 only Ca{sub 2−x}Li{sub 2x}GeO{sub 4} solid solutions of Ca{sub 2}GeO{sub 4} structure crystallized. The cell parameters of these solid solutions linearly decreased upon increasing the lithium concentration, which means that the solutions are in accordance with the Vegard's law. For 2x > 0.6 the specimens contained two phases: (i) Ca{sub 2−x}Li{sub 2x}GeO{sub 4} solid solutions with maximum lithium concentration approximately equal to that for 2x = 0.6 and minimum values of the cell parameters and (ii) Li{sub 2}CaGeO{sub 4} phase. Li{sub 2}O·MoO{sub 3}–Ca{sub 2}GeO{sub 4} high-temperature solutions were used to grow Ca{sub 2−x}Li{sub 2x}GeO{sub 4} solid solutions and Li{sub 2}CaGeO{sub 4} single crystals by the high temperature solution (flux) method. Li{sub 2}CaGeO{sub 4} crystals were grown in the concentration range 8–26 wt. % Ca{sub 2}GeO{sub 4} in the temperature range 830–980 °C. Crystals with chemical compositions of the Ca{sub 2−x}Li{sub 2x}GeO{sub 4} solid solutions with different Li concentrations were grown in the concentration range 26–40 wt. % Ca{sub 2}GeO{sub 4} in the temperature range 980–1090 °C. - Highlights: • Ca{sub 2−x}Li{sub 2x}GeO{sub 4} solid solutions are established for the first time. • The Li concentration range into the solutions is between 0 and 0.6. • The solid solutions are in accordance to Vegard's law. • Suitable solutions are found out for Ca{sub 2−x}Li{sub 2x}GeO{sub 4} and Li{sub 2}CaGeO{sub 4} crystal growth.

Dopamine/TiO{sub 2} hybrid thin films prepared by the liquid phase deposition method

Energy Technology Data Exchange (ETDEWEB)

Gutierrez-Tauste, David [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain)], E-mail: davidg@qf.uab.es; Domenech, Xavier [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain); Domingo, Concepcion [Instituto de Ciencia de Materiales (CSIC), Campus UAB, 08290 Cerdanyola del Valles, Barcelona (Spain); Ayllon, Jose A. [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain)

2008-04-30

Liquid phase deposition method is applied to one-step production of a hybrid material composed by dopamine(DA) and TiO{sub 2} anatase. An optimized amount of the enediol derivative is added to a fluoride titania precursor aqueous solution in order to entrap this modifier within the growing TiO{sub 2}, yielding a DA/TiO{sub 2} nanocomposite material. Uniform, well-adhered and brown-colored thin films are deposited on indium tin oxide covered glass substrate. The DA/TiO{sub 2} hybrid material has been characterized by infrared spectroscopy, electronic microscopy, X-ray diffraction and UV-vis spectroscopy. The formation of the hybrid material seems to be reasonably explained by linkage of different TiO{sub 2} nanocrystallites taking advantage of both enediol and amine groups of DA.

Manufacture of Bi-cuprate thin films on MgO single crystal substrates by chemical solution deposition

DEFF Research Database (Denmark)

Grivel, Jean-Claude; Bertelsen, Christian Vinther; Andersen, Niels Hessel

2014-01-01

Bi2Sr2CaCu2O8 thin films have been deposited on MgO single crystal substrates by spin-coating a solution based on 2-ethylhexanoate precursors dissolved in xylene. Pyrolysis takes place between 200°C and 450°C and is accompanied by the release of 2-ethylhexanoic acid, CO2 and H2O vapour. Highly c...

Enhancement of photocurrents due to the oxidation of water and organic compounds at BiZn2VO6 particulate thin film electrodes by treatment with a TiCl4 solution

International Nuclear Information System (INIS)

Liu Haimei; Imanishi, Akihito; Yang Wensheng; Nakato, Yoshihiro

2010-01-01

Photocurrents due to water oxidation at BiZn 2 VO 6 (E g 2.4 eV) particulate thin film electrodes were largely enhanced by pre-treatment with an aqueous TiCl 4 solution. Photocurrents for BiZn 2 VO 6 electrodes with no TiCl 4 treatment were also enhanced by the addition of organic compounds such as methanol and trimethyl amine to the aqueous electrolyte. Interestingly, such enhanced photocurrents by organic compounds were further enhanced by the TiCl 4 pre-treatment. EDAX and SEM investigations showed the formation of a flock-like TiO 2 overlayer on BiZn 2 VO 6 particles after the TiCl 4 treatment. The photocurrent enhancement by the TiCl 4 pre-treatment is thus mainly attributed to the necking effect of the flock-like TiO 2 overlayer, which facilitates the transport of photogenerated electrons within the BiZn 2 VO 6 particulate thin film electrode.

Manufacturing and investigation of surface morphology and optical properties of composite thin films reinforced by TiO2, Bi2O3 and SiO2 nanoparticles

Science.gov (United States)

Jarka, Paweł; Tański, Tomasz; Matysiak, Wiktor; Krzemiński, Łukasz; Hajduk, Barbara; Bilewicz, Marcin

2017-12-01

The aim of submitted paper is to present influence of manufacturing parameters on optical properties and surface morphology of composite materials with a polymer matrix reinforced by TiO2 and SiO2 and Bi2O3 nanoparticles. The novelty proposed by the authors is the use of TiO2 and SiO2 and Bi2O3 nanoparticles simultaneously in polymeric matrix. This allows using the combined effect of nanoparticles to a result composite material. The thin films of composite material were prepared by using spin-coating method with various spinning rates from solutions of different concentration of nanoparticles. In order to prepare the spinning solution polymer, Poly(methyl methacrylate) (PMMA) was used as a matrix. The reinforcing phase was the mixture of the nanoparticles of SiO2, TiO2 and B2O3. In order to identify the surface morphology of using thin films and arrangement of the reinforcing phase Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) were used. In order to study the optical properties of the obtained thin films, the thin films of composites was subjected to an ellipsometry analysis. The measurements of absorbance of the obtained materials, from which the value of the band gap width was specified, were carried out using the UV/VIS spectroscopy. The optical properties of obtain composite thin films depend not only on the individual components used, but also on the morphology and the interfacial characteristics. Controlling the participation of three kinds of nanoparticles of different sizes and optical parameters allows to obtaining the most optimal optical properties of nanocomposites and also controlling the deposition parameters allows to obtaining the most optimal surface morphology of nanocomposites.

(0 0 2-oriented growth and morphologies of ZnO thin films prepared by sol-gel method

Directory of Open Access Journals (Sweden)

Guo Dongyun

2016-09-01

Full Text Available Zinc acetate was used as a starting material to prepare Zn-solutions from solvents and ligands with different boiling temperature. The ZnO thin films were prepared on Si(1 0 0 substrates by spin-coating method. The effect of baking temperature and boiling temperature of the solvents and ligands on their morphologies and orientation was investigated. The solvents and ligands with high boiling temperature were favorable for relaxation of mechanical stress to form the smooth ZnO thin films. As the solvents and ligands with low boiling temperature were used to prepare Zn-solutions, the prepared ZnO thin films showed (0 0 2 preferred orientation. As n-propanol, 2-methoxyethanol, 2-(methylaminoethanol and monoethanolamine were used to prepare Zn-solutions, highly (0 0 2-oriented ZnO thin films were formed by adjusting the baking temperature.

Synthesis of nanocrystalline nickel-zinc ferrite (Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) thin films by chemical bath deposition method

Energy Technology Data Exchange (ETDEWEB)

Pawar, D.K. [Department of Chemistry, Shivaji University, Kolhapur 416 004 (M.S.) (India); Pawar, S.M. [Department of Materials Science and Engineering, Chonnam National University, 500 757 (Korea, Republic of); Patil, P.S. [Department of Physics, Shivaji University, Kolhapur 416 004 (M.S.) (India); Kolekar, S.S., E-mail: kolekarss2003@yahoo.co.in [Department of Chemistry, Shivaji University, Kolhapur 416 004 (M.S.) (India)

2011-02-24

Graphical abstract: Display Omitted Research highlights: > We have successfully synthesized nickel-zinc ferrite (Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) thin films on stainless steel substrates using a low temperature chemical bath deposition method. > The surface morphological study showed the compact flakes like morphology. > The as-deposited thin films are hydrophilic (10{sup o} < {theta} < 90{sup o}) whereas the annealed thin films are super hydrophilic ({theta} < 10{sup o}) in nature. > Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} thin films could be used in supercapacitor. - Abstract: The nickel-zinc ferrite (Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) thin films have been successfully deposited on stainless steel substrates using a chemical bath deposition method from alkaline bath. The films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), static water contact angle and cyclic voltammetry measurements. The X-ray diffraction pattern shows that deposited Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} thin films were oriented along (3 1 1) plane. The FTIR spectra showed strong absorption peaks around 600 cm{sup -1} which are typical for cubic spinel crystal structure. SEM study revealed compact flakes like morphology having thickness {approx}1.8 {mu}m after air annealing. The annealed films were super hydrophilic in nature having a static water contact angle ({theta}) of 5{sup o}.The electrochemical supercapacitor study of Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} thin films has been carried out in 6 M KOH electrolyte. The values of interfacial and specific capacitances obtained were 0.0285 F cm{sup -2} and 19 F g{sup -1}, respectively.

First identification and thermodynamic characterization of the ternary U(VI) species, UO2(O2)(CO3)2(4-), in UO2-H2O2-K2CO3 solutions.

Science.gov (United States)

Goff, George S; Brodnax, Lia F; Cisneros, Michael R; Peper, Shane M; Field, Stephanie E; Scott, Brian L; Runde, Wolfgang H

2008-03-17

In alkaline carbonate solutions, hydrogen peroxide can selectively replace one of the carbonate ligands in UO2(CO3)3(4-) to form the ternary mixed U(VI) peroxo-carbonato species UO2(O2)(CO3)2(4-). Orange rectangular plates of K4[UO2(CO3)2(O2)].H2O were isolated and characterized by single crystal X-ray diffraction studies. Crystallographic data: monoclinic, space group P2(1)/ n, a = 6.9670(14) A, b = 9.2158(10) A, c = 18.052(4) A, Z = 4. Spectrophotometric titrations with H 2O 2 were performed in 0.5 M K 2CO 3, with UO2(O2)(CO3)2(4-) concentrations ranging from 0.1 to 0.55 mM. The molar absorptivities (M(-1) cm(-1)) for UO2(CO3)3(4-) and UO2(O2)(CO3)2(4-) were determined to be 23.3 +/- 0.3 at 448.5 nm and 1022.7 +/- 19.0 at 347.5 nm, respectively. Stoichiometric analyses coupled with spectroscopic comparisons between solution and solid state indicate that the stable solution species is UO2(O2)(CO3)2(4-), which has an apparent formation constant of log K' = 4.70 +/- 0.02 relative to the tris-carbonato complex.

Optimization of time on CF_4/O_2 etchant for inductive couple plasma reactive ion etching of TiO_2 thin film

International Nuclear Information System (INIS)

Adzhri, R.; Fathil, M. F. M.; Ruslinda, A. R.; Gopinath, Subash C. B.; Voon, C. H.; Foo, K. L.; Nuzaihan, M. N. M.; Azman, A. H.; Zaki, M.; Arshad, M. K. Md.; Hashim, U.; Ayub, R. M.

2016-01-01

In this work, we investigate the optimum etching of titanium dioxide (TiO_2) using inductive couple plasma reactive ion etching (ICP-RIE) on our fabricated devices. By using a combination of CF_4/O_2 gases as plasma etchant with ratio of 3:1, three samples of TiO_2 thin film were etched with different time duration of 10 s, 15 s and 20 s. The ion bombardment of CF_4 gases with plasma enhancement by O_2 gas able to break the oxide bond of TiO_2 and allow anisotropic etch profile with maximum etch rate of 18.6 nm/s. The sample was characterized by using optical profilometer to determine the depth of etched area and scanning electron microscopy (SEM) for etch profile characterization.

TiO 2 Thin Films Prepared via Adsorptive Self-Assembly for Self-Cleaning Applications

KAUST Repository

Xi, Baojuan

2012-02-22

Low-cost controllable solution-based processes for preparation of titanium oxide (TiO 2) thin films are highly desirable, because of many important applications of this oxide in catalytic decomposition of volatile organic compounds, advanced oxidation processes for wastewater and bactericidal treatments, self-cleaning window glass for green intelligent buildings, dye-sensitized solar cells, solid-state semiconductor metal-oxide solar cells, self-cleaning glass for photovoltaic devices, and general heterogeneous photocatalysis for fine chemicals etc. In this work, we develop a solution-based adsorptive self-assembly approach to fabricate anatase TiO 2 thin films on different glass substrates such as simple plane glass and patterned glass at variable compositions (normal soda lime glass or solar-grade borofloat glass). By tuning the number of process cycles (i.e., adsorption-then-heating) of TiO 2 colloidal suspension, we could facilely prepare large-area TiO 2 films at a desired thickness and with uniform crystallite morphology. Moreover, our as-prepared nanostructured TiO 2 thin films on glass substrates do not cause deterioration in optical transmission of glass; instead, they improve optical performance of commercial solar cells over a wide range of incident angles of light. Our as-prepared anatase TiO 2 thin films also display superhydrophilicity and excellent photocatalytic activity for self-cleaning application. For example, our investigation of photocatalytic degradation of methyl orange indicates that these thin films are indeed highly effective, in comparison to other commercial TiO 2 thin films under identical testing conditions. © 2012 American Chemical Society.

CuAlO2 and CuAl2O4 thin films obtained by stacking Cu and Al films using physical vapor deposition

Science.gov (United States)

Castillo-Hernández, G.; Mayén-Hernández, S.; Castaño-Tostado, E.; DeMoure-Flores, F.; Campos-González, E.; Martínez-Alonso, C.; Santos-Cruz, J.

2018-06-01

CuAlO2 and CuAl2O4 thin films were synthesized by the deposition of the precursor metals using the physical vapor deposition technique and subsequent annealing. Annealing was carried out for 4-6 h in open and nitrogen atmospheres respectively at temperatures of 900-1000 °C with control of heating and cooling ramps. The band gap measurements ranged from 3.3 to 4.5 eV. Electrical properties were measured using the van der Pauw technique. The preferred orientations of CuAlO2 and CuAl2O4 were found to be along the (1 1 2) and (3 1 1) planes, respectively. The phase percentages were quantified using a Rietveld refinement simulation and the energy dispersive X-ray spectroscopy indicated that the composition is very close to the stoichiometry of CuAlO2 samples and with excess of aluminum and deficiency of copper for CuAl2O4 respectively. High resolution transmission electron microscopy identified the principal planes in CuAlO2 and in CuAl2O4. Higher purities were achieved in nitrogen atmosphere with the control of the cooling ramps.

Properties of NiO thin films deposited by chemical spray pyrolysis using different precursor solutions

Energy Technology Data Exchange (ETDEWEB)

Cattin, L. [Universite de Nantes, Nantes Atlantique Universites, LAMP, EA 3825, Faculte des Sciences et des Techniques, 2 rue de la Houssiniere, BP 92208, Nantes F-44000 (France); Reguig, B.A.; Khelil, A. [Universite d' Oran Es-Senia, LPCM2E (Algeria); Morsli, M. [Universite de Nantes, Nantes Atlantique Universites, LAMP, EA 3825, Faculte des Sciences et des Techniques, 2 rue de la Houssiniere, BP 92208, Nantes F-44000 (France); Benchouk, K. [Universite d' Oran Es-Senia, LPCM2E (Algeria); Bernede, J.C. [Universite de Nantes, Nantes Atlantique Universites, LAMP, EA 3825, Faculte des Sciences et des Techniques, 2 rue de la Houssiniere, BP 92208, Nantes F-44000 (France)], E-mail: Jean-Christian.Bernede@univ-nantes.fr

2008-07-15

NiO thin films have been deposited by chemical spray pyrolysis using a perfume atomizer to grow the aerosol. The influence of the precursor, nickel chloride hexahydrate (NiCl{sub 2}.6H{sub 2}O), nickel nitrate hexahydrate (Ni(NO{sub 3}){sub 2}.6H{sub 2}O), nickel hydroxide hexahydrate (Ni(OH){sub 2}.6H{sub 2}O), nickel sulfate tetrahydrate (NiSO{sub 4}.4H{sub 2}O), on the thin films properties has been studied. In the experimental conditions used (substrate temperature 350 deg. C, precursor concentration 0.2-0.3 M, etc.), pure NiO thin films crystallized in the cubic phase can be achieved only with NiCl{sub 2} and Ni(NO{sub 3}){sub 2} precursors. These films have been post-annealed at 425 deg. C for 3 h either in room atmosphere or under vacuum. If all the films are p-type, it is shown that the NiO films conductivity and optical transmittance depend on annealing process. The properties of the NiO thin films annealed under room atmosphere are not significantly modified, which is attributed to the fact that the temperature and the environment of this annealing is not very different from the experimental conditions during spray deposition. The annealing under vacuum is more efficient. This annealing being proceeded in a vacuum no better than 10{sup -2} Pa, it is supposed that the modifications of the NiO thin film properties, mainly the conductivity and optical transmission, are related to some interaction between residual oxygen and the films.

Structural and optical properties of ZnO–SnO{sub 2} mixed thin films deposited by spray pyrolysis

Energy Technology Data Exchange (ETDEWEB)

Tharsika, T., E-mail: tharsika@siswa.um.edu.my; Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Sabri, M.F.M., E-mail: faizul@um.edu.my

2014-05-02

Nanocrystalline ZnO–SnO{sub 2} mixed thin films were deposited by the spray pyrolysis technique at various substrate temperatures during deposition. The mixed films were prepared in the range of 20.9 at.% to 73.4 at.% by altering the Zn/(Sn + Zn) atomic ratio in the starting solution. Morphology, crystal structures, and optical properties of the films were characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and ultraviolet–visible and photoluminescence (PL) spectroscopy. XRD analysis reveals that the crystallinity of the Sn-rich mixed thin films increases with increasing substrate temperatures. FESEM images show that the grain size of mixed thin films is smaller compared to that of pure ZnO and SnO{sub 2} thin films. A drop in the thickness and optical bandgap of the film was observed for films fabricated at high temperatures, which coincided with the increased crystallinity of the films. The average optical transmission of mixed thin films increased from 70% to 95% within the visible range (400–800 nm) as the substrate temperature increases. Optical bandgap of the films was determined to be in the range of 3.21–3.96 eV. The blue shift in the PL spectra from the films was supported by the fact that grain size of the mixed thin films is much smaller than that of the pure ZnO and SnO{sub 2} thin films. Due to the improved transmission and reduced grain size, the ZnO–SnO{sub 2} mixed thin films can have potential use in photovoltaic and gas sensing applications. - Highlights: • ZnO–SnO{sub 2} mixed thin films were deposited on glass substrate by spray pyrolysis. • Crystallinity of the thin films increases with substrate temperature. • Grain size of the mixed thin films is smaller than that of the pure thin films. • Reduction of grain size depends on mixed atomic ratios of precursor solution. • Optical band gap of films could be engineered by changing substrate temperature.

Double molybdates in Li2MoO4 - Na2MoO4 - H2O system at 25 grad C

International Nuclear Information System (INIS)

Karov, Z.G.; Mirzoev, R.S.; Makitova, D.D.; Zhilova, S.B.; Podnek, A.G.; Urusova, R.Kh.

1989-01-01

Solubility in Li 2 MoO 4 - Na 2 MoO 4 - H 2 O system at 25 deg C is first stuied. Formation of two Li 2 MoO 4 · Na 2 MoO 4 · 4H 2 O and Li 2 MoO 4 · 3Na 2 MoO 4 · 12H 2 O compounds in a system is ascertained. Density, refractive index, viscosity, surface tension, electric conductivity and pH of saturated solutions are determined. Isothermes of mole volume, equivalent and reduced electric conductivity and seeming mole volume of salts sum in solutions are calculated. All these properties adequtely confirm the character of components interaction in a system determined by solubility method. Crystallhydrates of binary molybdates are separated, indentified and studied

Disappearance of superconductivity in the solid solution between (Ca4Al2O6)(Fe2As2) and (Ca4Al2O6)(Fe2P2) superconductors.

Science.gov (United States)

Shirage, Parasharam M; Kihou, Kunihiro; Lee, Chul-Ho; Takeshita, Nao; Eisaki, Hiroshi; Iyo, Akira

2012-09-19

The effect of alloying the two perovskite-type iron-based superconductors (Ca(4)Al(2)O(6))(Fe(2)As(2)) and (Ca(4)Al(2)O(6))(Fe(2)P(2)) was examined. While the two stoichiometric compounds possess relatively high T(c)'s of 28 and 17 K, respectively, their solid solutions of the form (Ca(4)Al(2)O(6))(Fe(2)(As(1-x)P(x))(2)) do not show superconductivity over a wide range from x = 0.50 to 0.95. The resultant phase diagram is thus completely different from those of other typical iron-based superconductors such as BaFe(2)(As,P)(2) and LaFe(As,P)O, in which superconductivity shows up when P is substituted for As in the non-superconducting "parent" compounds. Notably, the solid solutions in the non-superconducting range exhibit resistivity anomalies at temperatures of 50-100 K. The behavior is reminiscent of the resistivity kink commonly observed in various non-superconducting parent compounds that signals the onset of antiferromagnetic/orthorhombic long-range order. The similarity suggests that the suppression of the superconductivity in the present case also has a magnetic and/or structural origin.

Preparation of acid salt M(HPO4)2.nH2 O thin films

International Nuclear Information System (INIS)

Kassem, M.

1998-01-01

The layered crystalline powders of Titanium Phosphate with the formula Ti(HPO 4 ) 2 .nH 2 O (phase α when n=2, phase γ when n=1) were prepared by reaction of titanium three chloride with phosphoric acid under specific thermal conditions. Starting from these powders thin films have been prepared using some methods such as: Thermal evaporation, sol-gel and vapor phase transport. The results of X-ray diffraction and differential thermal deferential analysis show that the temperature plays an important role in the determination of the crystalline phases and the phase transition of the prepared films. (author). 7 refs

Electrical and optical properties of thermally-evaporated thin films from A{sub 2}[TiO(C{sub 2}O{sub 4}){sub 2}] (A = K, PPh{sub 4}) and 1,8-dihydroxyanthraquinone

Energy Technology Data Exchange (ETDEWEB)

Carbia-Ruelas, E. [Coordinacion de Ingenieria Mecatronica. Facultad de Ingenieria, Universidad Anahuac Mexico Norte. Avenida Universidad Anahuac 46, Col. Lomas Anahuac, 52786, Huixquilucan (Mexico); Sanchez-Vergara, M.E., E-mail: elena.sanchez@anahuac.mx [Coordinacion de Ingenieria Mecatronica. Facultad de Ingenieria, Universidad Anahuac Mexico Norte. Avenida Universidad Anahuac 46, Col. Lomas Anahuac, 52786, Huixquilucan (Mexico); Garcia-Montalvo, V. [Instituto de Quimica, Universidad Nacional Autonoma de Mexico. Circuito Exterior, Ciudad Universitaria, 04510, Mexico, D. F (Mexico); Morales-Saavedra, O.G. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, CCADET-UNAM. A. P. 70-186, Coyoacan, 04510, Mexico, D. F (Mexico); Alvarez-Bada, J.R. [Coordinacion de Ingenieria Mecatronica. Facultad de Ingenieria, Universidad Anahuac Mexico Norte. Avenida Universidad Anahuac 46, Col. Lomas Anahuac, 52786, Huixquilucan (Mexico)

2011-02-01

In this work, the synthesis of molecular materials formed from A{sub 2}[TiO(C{sub 2}O{sub 4}){sub 2}] (A = K, PPh4) and 1,8 dihydroxyanthraquinone is reported. The synthesized materials were characterized by atomic force microscopy (AFM), infrared (IR) and ultraviolet-visible (UV-vis) spectroscopy. IR spectroscopy showed that the molecular-material thin-films, deposited by vacuum thermal evaporation, exhibit the same intra-molecular vibration modes as the starting powders, which suggests that the thermal evaporation process does not alter the initial chemical structures. Electrical transport properties were studied by dc conductivity measurements. The electrical activation energies of the complexes, which were in the range of 0.003-1.16 eV, were calculated from Arrhenius plots. Optical absorption studies in the wavelength range of 190-1090 nm at room temperature showed that the optical band gaps of the thin films were around 1.9-2.3 eV for direct transitions Eg{sub d}. The cubic NLO effects were substantially enhanced for materials synthesized from K{sub 2}[TiO(C{sub 2}O{sub 4}){sub 2}], where {chi}{sup (3)} (-3{omega}; {omega}, {omega}, {omega}) values in the promising range of 10{sup -12} esu have been evaluated.

Surface Modification of Solution-Processed ZrO2 Films through Double Coating for Pentacene Thin-Film Transistors

Science.gov (United States)

Kwon, Jin-Hyuk; Bae, Jin-Hyuk; Lee, Hyeonju; Park, Jaehoon

2018-03-01

We report the modification of surface properties of solution-processed zirconium oxide (ZrO2) dielectric films achieved by using double-coating process. It is proven that the surface properties of the ZrO2 film are modified through the double-coating process; the surface roughness decreases and the surface energy increases. The present surface modification of the ZrO2 film contributes to an increase in grain size of the pentacene film, thereby increasing the field-effect mobility and decreasing the threshold voltage of the pentacene thin-film transistors (TFTs) having the ZrO2 gate dielectric. Herein, the molecular orientation of pentacene film is also studied based on the results of contact angle and X-ray diffraction measurements. Pentacene molecules on the double-coated ZrO2 film are found to be more tilted than those on the single-coated ZrO2 film, which is attributed to the surface modification of the ZrO2 film. However, no significant differences are observed in insulating properties between the single-and the double-coated ZrO2 dielectric films. Consequently, the characteristic improvements of the pentacene TFTs with the double-coated ZrO2 gate dielectric film can be understood through the increase in pentacene grain size and the reduction in grain boundary density.

Apparent molar volumes for dilute solutions of NaClO4 and [Co(en) 3](ClO4)3 in D2O and H2O at 278-318 K

International Nuclear Information System (INIS)

Bottomley, G.A.; Glossop, L.G.

1981-01-01

Apparent molar volumes for dilute solutions of NaClO 4 and [Co(en) 3 ](ClO 4 ) 3 in D 2 O and H 2 O were measured by using a dilatometry technique at 278, 298 and 318K. Comparison of limiting slopes with the Debye-Huckel predictions from the dielectric constant and compressibility of H 2 O and D 2 O is complicated by ion pairing. The apparent molar volumes for NaClO 4 were less in D 2 O than in H 2 O. The complex [Co(en) 3 ](ClO 4 ) 3 when studied in D 2 O had its amine protons exchanged by deuterium; this did not allow a direct comparison of the apparent molar volumes of the protonated complex in each solvent system, but revealed a large isotope effect. The apparent molar volumes of the [Co(en) 3 ](ClO 4 ) 3 showed a much larger temperature dependence than that of NaClO 4

Structural and optical properties of (Sr,Ba)2SiO4:Eu2+ thin films grown by magnetron sputtering

International Nuclear Information System (INIS)

Li, Leliang; Zheng, Jun; Zuo, Yuhua; Cheng, Buwen; Wang, Qiming

2014-01-01

(Sr,Ba) 2 SiO 4 :Eu 2+ thin films were deposited on Si at different substrate temperatures by magnetron sputtering. The morphology and crystalline phases of the films were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements, respectively. The silicate crystal phase was presented when films were annealed above 900 °C and the annealing temperature had great impact on the film morphology. The samples annealed at 1000 °C in a non-reducing atmosphere for 30 s show intense room temperature Eu 2+ emission. These findings may open a promising way to prepare efficient phosphor thin films for on-chip light emitting diodes application. - Highlights: • The (Sr, Ba) 2 SiO 4 :Eu 2+ films are fabricated by magnetron sputtering. • A very strong RT PL emission at 540 nm is achieved. • The morphology and optical properties dependent on temperature are studied

Ferroelectric properties of bilayer structured Pb(Zr0.52Ti0.48)O3/SrBi2Ta2O9 (PZT/SBT) thin films on Pt/TiO2/SiO2/Si substrates

International Nuclear Information System (INIS)

Zhang Wenqi; Li Aidong; Shao Qiyue; Xia Yidong; Wu Di; Liu Zhiguo; Ming Naiben

2008-01-01

Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films with large remanent polarization and SrBi 2 Ta 2 O 9 (SBT) thin films with excellent fatigue-resisting characteristic have been widely studied for non-volatile random access memories, respectively. To combine these two advantages , bilayered Pb(Zr 0.52 Ti 0.48 )O 3 /SrBi 2 Ta 2 O 9 (PZT/SBT) thin films were fabricated on Pt/TiO 2 /SiO 2 /Si substrates by chemical solution deposition method. X-ray diffraction patterns revealed that the diffraction peaks of PZT/SBT thin films were completely composed of PZT and SBT, and no other secondary phase was observed. The electrical properties of the bilayered structure PZT/SBT films have been investigated in comparison with pure PZT and SBT films. PZT/SBT bilayered thin films showed larger remanent polarization (2P r ) of 18.37 μC/cm 2 than pure SBT and less polarization fatigue up to 1 x 10 9 switching cycles than pure PZT. These results indicated that this bilayered structure of PZT/SBT is a promising material combination for ferroelectric memory applications

Facile Synthesis of Novel Nanostructured MnO2Thin Films and Their Application in Supercapacitors

Directory of Open Access Journals (Sweden)

Xia H

2009-01-01

Full Text Available Abstract Nanostructured α-MnO2thin films with different morphologies are grown on the platinum substrates by a facile solution method without any assistance of template or surfactant. Microstructural characterization reveals that morphology evolution from dandelion-like spheres to nanoflakes of the as-grown MnO2is controlled by synthesis temperature. The capacitive behavior of the MnO2thin films with different morphologies are studied by cyclic voltammetry. The α-MnO2thin films composed of dandelion-like spheres exhibit high specific capacitance, good rate capability, and excellent long-term cycling stability.

Structural relaxation and colour in the spinel-magnesiochromite (MgAl2O4-MgCr2O4) and gahnite-zincochromite (ZnAl2O4-ZnCr2O4) solid solution series

Science.gov (United States)

Hålenius, U.; Andreozzi, G. B.; Skogby, H.

2009-04-01

Recent studies on binary mineral solid solution series utilising synchrotron based x-ray absorption spectroscopies have indicated strong structural relaxation. For instance, it has been suggested that the real Cr-O bond distances remain nearly constant (relaxation parameter (ɛ) of 0.85, where ɛ=1 equals full relaxation) over the entire compositional range of the MgAl2O4-MgCr2O4 series (Juhin et al. 2007). In the present study we have measured room temperature optical absorption spectra of synthetic single crystals of the ZnAl2-2xCr2xO4 (0.03?x?1) and MgAl2-2xCr2xO4(0.02?x?1) series with the aim to explore the real architecture of the structure and in particular the Cr-O distance as function of composition. Our crystals were synthesized by means of flux-growth methods under atmospheric pressure and temperature profiles resulting in an estimated cation ordering temperature of ca 850 °C. Crystals close to the spinel (sensu stricto) and gahnite end-member compositions were faintly red in colour. With increasing Cr-content the crystals become more intensely red-coloured and at the higher Cr-contents there is a distinct shift towards a dark greenish colouration. These colour changes are reflected in the measured optical spectra by the position and intensity of the two spin-allowed electronic d-d transitions in octahedrally coordinated Cr3+ at ca 18000 (4A2g -4T2g (4F) transition) and 25000 cm-1(4A2g -4T1g (4F) transition). The energy of the first transition (?1-band) is ca 1200 cm-1 lower in magnesiochromite than in weakly Cr-doped spinel (x=0.02) and ca 1400 cm-1 lower in zincochromite than in gahnite with the lowest Cr-content (x=0.03). Concomitantly the energy of the second transition (?2-band) decreases with increasing Cr-content in both series by ca. 1800 cm-1. From the position of the ?1-band, a decrease in crystal field splitting, 10Dq, for six-coordinated Cr3+ with increasing Cr-content in the MgAl2-2xCr2xO4 and ZnAl2-2xCr2xO4 series of 6.5 and 7

A New High Energy Lithium ion Batteries Consisting of 0.5Li2MnO3·0.5LiMn0.33Ni0.33Co0.33O2 and Soft Carbon Components

International Nuclear Information System (INIS)

Wang, Tao; Chen, Zhanjun; Zhao, Ruirui; Li, Aiju; Chen, Hongyu

2016-01-01

Electrochemical performance of the 18650 lithium-ion batteries consisting lithium-rich layered oxides 0.5Li 2 MnO 3 ·0.5LiMn 0.33 Ni 0.33 Co 0.33 O 2 cathode material and soft carbon anode is investigated in detail. The cathode is synthesized by a spray drying process and the properties are studied by various methods, while the soft carbon is commercial available. The assembled batteries can exhibit excellent cyclic performance with a capacity retention of 90.2% even after 600 cycles in the voltage ranges of 2.0-4.5 V (at 1C-rate). Moreover, they can also deliver excellent rate capabilities as the discharge capacity under 40C is nearly equal to 83.9% of that under 1C (voltage range is in 2.0-4.5 V). Furthermore, in order to evaluate the mechanism of the superior performance exhibited by the full cells, cells after 300 cycles are disassembled in a glove box to assess the changes on the active materials by using a series of technique methods, including a scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), High-resolution transmission electron microscope (TEM) and selected area electron diffraction (SAED).

Optical and structural properties of natural MnSeO{sub 4} mineral thin film

Energy Technology Data Exchange (ETDEWEB)

Kariper, Ishak Afsin, E-mail: akariper@gmail.com [Erciyes University, Education Faculty, Kayseri (Turkey)

2017-05-15

Manganese selenite (MnSeO{sub 4}) crystalline thin film has been produced with chemical bath deposition on substrates (commercial glass). Properties of the thin film, such as transmittance, absorption, and optical band gap and refraction index have been investigated via UV/VIS Spectrum. The structural properties of orthorhombic form have been observed in XRD. The structural and optical properties of MnSeO{sub 4} thin films, deposited at different pH levels were analyzed. Some properties of the films have been changed with the change of pH level, which has been deeply investigated. The grain size of MnSeO{sub 4} thin film has reached its highest value at pH 9. The refraction index and extinction coefficient of MnSeO{sub 4} thin films were measured to be 1.53, 2.86, 2.07, 1.53 (refraction index) and 0.005, 0.029, 0.014, 0.005 (extinction coefficient) for grain sizes 21, 13, 26, and 5 nm respectively. The band gaps (Eg) of the films were measured to be 2.06, 2.57, 2.04, and 2.76 eV for the grain sizes mentioned above. The value of dielectric constant at pH 10 was calculated as 1.575. (author)

TiO{sub 2} and TiO{sub 2}-SiO{sub 2} thin films and powders by one-step soft-solution method: Synthesis and characterizations

Energy Technology Data Exchange (ETDEWEB)

Ennaoui, A.; Sankapal, B.R.; Skryshevsky, V.; Lux-Steiner, M.Ch. [Division Solar Energy Research, Department Heterogeneous Material Systems, Hahn-Meitner-Institut, Glienicker Strasse 100, 14109 Berlin (Germany)

2006-06-15

Simple soft-solution method has been developed to synthesize films and powders of TiO{sub 2} and mixed TiO{sub 2}-SiO{sub 2} at relatively low temperatures. This method is simple and inexpensive. Furthermore, reactor can be designed for large-scale applications as well as to produce large quantities of composite powders in a single step. For the preparation of TiO{sub 2}, we used aqueous acidic medium containing TiOSO{sub 4} and H{sub 2}O{sub 2}, which results in a peroxo-titanium precursor while colloidal SiO{sub 2} has been added to the precursor for the formation of TiO{sub 2}-SiO{sub 2}. Post annealing at 500{sup o}C is necessary to have anatase structure. Resulting films and powders were characterized by different techniques. TiO{sub 2} (anatase) phase with (101) preferred orientation has been obtained. Also in TiO{sub 2}-SiO{sub 2} mixed films and powders, TiO{sub 2} (anatase) phase was found. Fourier transform infrared spectroscopy (FTIR) results for TiO{sub 2} and mixed TiO{sub 2}-SiO{sub 2} films have been presented and discussed. The method developed in this paper allowed obtaining compact and homogeneous TiO{sub 2} films. These compact films are highly photoactive when TiO{sub 2} is used as photo anode in an photoelectrochemical cell. Nanoporous morphology is obtained when SiO{sub 2} colloids are added into the solution. (author)

Systems of OsO4-RuO4 and Re2O7-OsO4

International Nuclear Information System (INIS)

Nisel'son, L.A.; Sokolova, T.D.; Orlov, A.M.; Shorikov, Yu.S.

1981-01-01

The meltability diagrams of the systems OsO 4 -RuO 4 and Re 2 O 7 -OsO 4 are studied using the visual-polythermal method. The OsO 4 -RuO 4 system forms a continuous series of solid solutions with practically rectilinear line of the liquidus. The Re 2 O 7 -OsO 4 system of the eutectic type has the eutectics degenerated from the side of OsO 4 . For the system OsO 4 (basis)-RuO 4 (admixture) the equilibrium coefficient of distribution is determined using the method of directed crystallization [ru

Bias Stability Enhancement in Thin-Film Transistor with a Solution-Processed ZrO2 Dielectric as Gate Insulator

Directory of Open Access Journals (Sweden)

Shangxiong Zhou

2018-05-01

Full Text Available In this paper, a high-k metal-oxide film (ZrO2 was successfully prepared by a solution-phase method, and whose physical properties were measured by X-ray diffraction (XRD, X-ray reflectivity (XRR and atomic force microscopy (AFM. Furthermore, indium–gallium–zinc oxide thin-film transistors (IGZO-TFTs with high-k ZrO2 dielectric layers were demonstrated, and the electrical performance and bias stability were investigated in detail. By spin-coating 0.3 M precursor six times, a dense ZrO2 film, with smoother surface and fewer defects, was fabricated. The TFT devices with optimal ZrO2 dielectric exhibit a saturation mobility up to 12.7 cm2 V−1 s−1, and an on/off ratio as high as 7.6 × 105. The offset of the threshold voltage was less than 0.6 V under positive and negative bias stress for 3600 s.

Nanocrystalline Sr2CeO4 thin films grown on silicon by laser ablation

International Nuclear Information System (INIS)

Perea, Nestor; Hirata, G.A.

2006-01-01

Blue-white luminescent Sr 2 CeO 4 thin films were deposited by using pulsed laser ablation (λ = 248 nm wavelength) on 500 deg. C silicon (111) substrates under an oxygen pressure of 55 mTorr. High-resolution electron transmission microscopy, electron diffraction and X-ray diffraction analysis revealed that the films were composed of nanocrystalline Sr 2 CeO 4 grains of the order of 20-30 nm with a preferential orientation in the (130) crystallographic direction. The excitation and photoluminescence spectra measured on the films maintained the characteristic emission of bulk Sr 2 CeO 4 however, the emission peak appeared narrower and blue-shifted as compared to the luminescence spectrum of the target. The blue-shift and a preferential crystallographic orientation during the growth formation of the film is related to the nanocrystalline nature of the grains due to the quantum confinement behavior and surface energy minimization in nanostructured systems

Texture-Etched SnO2 Glasses Applied to Silicon Thin-Film Solar Cells

Directory of Open Access Journals (Sweden)

Bing-Rui Wu

2014-01-01

Full Text Available Transparent electrodes of tin dioxide (SnO2 on glasses were further wet-etched in the diluted HCl:Cr solution to obtain larger surface roughness and better light-scattering characteristic for thin-film solar cell applications. The process parameters in terms of HCl/Cr mixture ratio, etching temperature, and etching time have been investigated. After etching process, the surface roughness, transmission haze, and sheet resistance of SnO2 glasses were measured. It was found that the etching rate was increased with the additions in etchant concentration of Cr and etching temperature. The optimum texture-etching parameters were 0.15 wt.% Cr in 49% HCl, temperature of 90°C, and time of 30 sec. Moreover, silicon thin-film solar cells with the p-i-n structure were fabricated on the textured SnO2 glasses using hot-wire chemical vapor deposition. By optimizing the texture-etching process, the cell efficiency was increased from 4.04% to 4.39%, resulting from the increment of short-circuit current density from 14.14 to 15.58 mA/cm2. This improvement in cell performances can be ascribed to the light-scattering effect induced by surface texturization of SnO2.

Rapid removal of uranium from aqueous solutions using magnetic Fe3O4@SiO2 composite particles.

Science.gov (United States)

Fan, Fang-Li; Qin, Zhi; Bai, Jing; Rong, Wei-Dong; Fan, Fu-You; Tian, Wei; Wu, Xiao-Lei; Wang, Yang; Zhao, Liang

2012-04-01

Rapid removal of U(VI) from aqueous solutions was investigated using magnetic Fe(3)O(4)@SiO(2) composite particles as the novel adsorbent. Batch experiments were conducted to study the effects of initial pH, amount of adsorbent, shaking time and initial U(VI) concentrations on uranium sorption efficiency as well as the desorbing of U(VI). The sorption of uranium on Fe(3)O(4)@SiO(2) composite particles was pH-dependent, and the optimal pH was 6.0. In kinetics studies, the sorption equilibrium can be reached within 180 min, and the experimental data were well fitted by the pseudo-second-order model, and the equilibrium sorption capacities calculated by the model were almost the same as those determined by experiments. The Langmuir sorption isotherm model correlates well with the uranium sorption equilibrium data for the concentration range of 20-200 mg/L. The maximum uranium sorption capacity onto magnetic Fe(3)O(4)@SiO(2) composite particles was estimated to be about 52 mg/g at 25 °C. The highest values of uranium desorption (98%) was achieved using 0.01 M HCl as the desorbing agent. Fe(3)O(4)@SiO(2) composite particles showed a good selectivity for uranium from aqueous solution with other interfering cation ions. Present study suggested that magnetic Fe(3)O(4)@SiO(2) composite particles can be used as a potential adsorbent for sorption uranium and also provided a simple, fast separation method for removal of heavy metal ion from aqueous solution. Copyright © 2011 Elsevier Ltd. All rights reserved.

Complexing in the system Rb2SeO4-UO2SeO4-H2O

International Nuclear Information System (INIS)

Kuchumova, N.V.; Shtokova, I.P.; Serezhkina, L.B.; Serezhkin, V.N.

1989-01-01

Method of isothermal solubility at 25 deg C is used to study interaction of rubidium and uranyl selenates in aqueous solution. Formation of congruently soluble Rb 2 UO 2 (SeO 4 ) 2 x2H 2 O and Rb 2 (UO 2 ) 2 x(SeO 4 ) 3 x6H 2 O is stated. For the last compound crystallographic characteristics (a=10.668; b=14.935(9); c=13.891(7) A; β=104.94(1); Z=4, sp.gr. P2 1 /c) are determined. Thermal decomposition of a compound results in formation of Rb 2 U 2 O 7

Cs2SeO4-UO2SeO4-H2O system at 25 deg C

International Nuclear Information System (INIS)

Serezhkina, L.B.; Serezhkin, V.N.

1987-01-01

Using the method of isothermal solubility at 25 deg C the interaction of cesium and uranyl selenates in aqueous solution is studied. Formation of congruently soluble Cs 2 UO 2 (SeO 4 ) 2 x2H 2 O and Cs 2 (UO 2 ) 2 x(SeO 4 ) 3 is ascertained, their crystallographic characteristics being determined

Highly Sensitive Nanostructured SnO2 Thin Films For Hydrogen Sensing

Science.gov (United States)

Patil, L. A.; Shinde, M. D.; Bari, A. R.; Deo, V. V.

2010-10-01

Nanostructured SnO2 thin films were prepared by ultrasonic spray pyrolysis technique. Aqueous solution (0.05 M) of SnCl4ṡ5H2O in double distilled water was chosen as the starting solution for the preparation of the films. The stock solution was delivered to nozzle with constant and uniform flow rate of 70 ml/h by Syringe pump SK5001. Sono-tek spray nozzle, driven by ultrasonic frequency of 120 kHz, converts the solution into fine spray. The aerosol produced by nozzle was sprayed on glass substrate heated at 150 °C. The sensing performance of the films was tested for various gases such as LPG, hydrogen, ethanol, carbon dioxide and ammonia. The sensor (30 min) showed high gas response (S = 3040 at 350 °C) on exposure of 1000 ppm of hydrogen and high selectivity against other gases. Its response time was short (2 s) and recovery was also fast (12 s). To understand reasons behind this uncommon gas sensing performance of the films, their structural, microstructural, and optical properties were studied using X-ray diffraction, electron microscopy (SEM and TEM) respectively. The results are interpreted

Li4SiO4-Based Artificial Passivation Thin Film for Improving Interfacial Stability of Li Metal Anodes.

Science.gov (United States)

Kim, Ji Young; Kim, A-Young; Liu, Guicheng; Woo, Jae-Young; Kim, Hansung; Lee, Joong Kee

2018-03-14

An amorphous SiO 2 (a-SiO 2 ) thin film was developed as an artificial passivation layer to stabilize Li metal anodes during electrochemical reactions. The thin film was prepared using an electron cyclotron resonance-chemical vapor deposition apparatus. The obtained passivation layer has a hierarchical structure, which is composed of lithium silicide, lithiated silicon oxide, and a-SiO 2 . The thickness of the a-SiO 2 passivation layer could be varied by changing the processing time, whereas that of the lithium silicide and lithiated silicon oxide layers was almost constant. During cycling, the surface of the a-SiO 2 passivation layer is converted into lithium silicate (Li 4 SiO 4 ), and the portion of Li 4 SiO 4 depends on the thickness of a-SiO 2 . A minimum overpotential of 21.7 mV was observed at the Li metal electrode at a current density of 3 mA cm -2 with flat voltage profiles, when an a-SiO 2 passivation layer of 92.5 nm was used. The Li metal with this optimized thin passivation layer also showed the lowest charge-transfer resistance (3.948 Ω cm) and the highest Li ion diffusivity (7.06 × 10 -14 cm 2 s -1 ) after cycling in a Li-S battery. The existence of the Li 4 SiO 4 artificial passivation layer prevents the corrosion of Li metal by suppressing Li dendritic growth and improving the ionic conductivity, which contribute to the low charge-transfer resistance and high Li ion diffusivity of the electrode.

Structure and electrical properties of (La, Zn) Co-doped BiFeO3 thin films prepared by using chemical solution deposition

Science.gov (United States)

Kim, Y. J.; Kim, H. J.; Kim, J. W.; Raghavan, C. M.; Kim, S. S.

2012-08-01

We prepared pure BiFeO3 (BFO) and (Bi0.9La0.1)(Fe0.975Zn0.025)O3- δ (BLFZO) thin films on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. Improved electrical properties were observed in the co-doped BLFZO thin film. The leakage current density of the BLFZO thin film was four orders of magnitude lower than that of the pure BFO, 4.17 × 10-7 A/cm2 at 100 kV/cm. The remnant polarization (2 P r ) and the coercive electric field (2 E c ) of the BLFZO thin film were 97 µC/cm2 and 903 kV/cm at an applied electric field of 972 kV/cm and at a frequency of 1 kHz, and the values decreased with increasing measurement frequency to 63 µC/cm2 and 679 kV/cm at 10 kHz, respectively. Also, after 1.44 × 1010 cycles, a better fatigue endurance was observed in the BLFZO thin film, which was 90% of its initial value. We also confirmed that the remnant polarization (2 P r ) and the coercive electric field (2 E c ) were fairly saturated above a measurement frequency of 15 kHz for the BLFZO thin film.

Thin-Film Photoluminescent Properties and the Atomistic Model of Mg2TiO4 as a Non-rare Earth Matrix Material for Red-Emitting Phosphor

Science.gov (United States)

Huang, Chieh-Szu; Chang, Ming-Chuan; Huang, Cheng-Liang; Lin, Shih-kang

2016-12-01

Thin-film electroluminescent devices are promising solid-state lighting devices. Red light-emitting phosphor is the key component to be integrated with the well-established blue light-emitting diode chips for stimulating natural sunlight. However, environmentally hazardous rare-earth (RE) dopants, e.g. Eu2+ and Ce2+, are commonly used for red-emitting phosphors. Mg2TiO4 inverse spinel has been reported as a promising matrix material for "RE-free" red light luminescent material. In this paper, Mg2TiO4 inverse spinel is investigated using both experimental and theoretical approaches. The Mg2TiO4 thin films were deposited on Si (100) substrates using either spin-coating with the sol-gel process, or radio frequency sputtering, and annealed at various temperatures ranging from 600°C to 900°C. The crystallinity, microstructures, and photoluminescent properties of the Mg2TiO4 thin films were characterized. In addition, the atomistic model of the Mg2TiO4 inverse spinel was constructed, and the electronic band structure of Mg2TiO4 was calculated based on density functional theory. Essential physical and optoelectronic properties of the Mg2TiO4 luminance material as well as its optimal thin-film processing conditions were comprehensively reported.

Modified voltammetric, impedimetric and optical behavior of polymer- assisted sol-gel MgFe2O4 nanostructured thin films

International Nuclear Information System (INIS)

Bazhan, Z.; Ghodsi, F.E.; Mazloom, J.

2017-01-01

Highlights: •Electrochemical properties of spinel PEG/PVP MgFe 2 O 4 thin films prepared by spin coating technique have been investigated. •PSD analysis indicated that spectral roughness of films decreased by polymer incorporation. •Optical calculations exhibited a blue shift on optical band gap by polymer addition. •CV curves revealed that ion storage capacitance of PEG/MgFe 2 O 4 is two times higher than MgFe 2 O 4 thin films. •EIS analysis confirmed that incorporation of appropriate amount of PEG reduced the charge transfer resistance. -- Abstract: The effect of polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) on physical properties of sol-gel prepared magnesium ferrite (MF) thin films was investigated. The X-ray diffraction (XRD) results showed the formation of cubic spinel magnesium ferrite for all samples. The surface morphology of films changed and average surface roughness decreased by polymer addition. The height-height correlation function and fractal dimension were evaluated using cube counting and triangulation methods from atomic force microscopy (AFM) images. The refractive index and extinction coefficient of MF thin films decreased by adding polymer while the band gap value increased from 2.24 to 2.72 eV. The PEG addition enhanced the electrochemical performance while PVP addition didn’t have significant effect on cyclic voltammetry (CV) of magnesium ferrite thin films. The sample with highest value of PEG showed the maximum specific capacitance (68.5 mF cm −2 ) and the smallest charge transfer resistance (565 Ω) among all samples.

solution growth and characterization of copper oxide thin films ...

African Journals Online (AJOL)

Thin films of copper oxide (CuO) were grown on glass slides by using the solution growth technique. Copper cloride (CuCl ) and potassium telluride (K T O ) were used. Buffer 2 2e 3 solution was used as complexing agent. The solid state properties and optical properties were obtained from characterization done using PYE ...

Electron transport properties of some new 4-tert-butylcalix[4]arene derivatives in thin films

Energy Technology Data Exchange (ETDEWEB)

Leontie, Liviu, E-mail: lleontie@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, B-dul Carol I, Nr. 11, 700506 Iasi (Romania); Danac, Ramona [Faculty of Chemistry, Alexandru Ioan Cuza University of Iasi, B-dul Carol I, Nr. 11, 700506 Iasi (Romania); Girtan, Mihaela [Laboratoire LPhiA, Angers University, 2, Bd. Lavoisier, 49045, Angers (France); Carlescu, Aurelian; Rambu, Alicia Petronela; Rusu, Gheorghe I. [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, B-dul Carol I, Nr. 11, 700506 Iasi (Romania)

2012-07-16

Temperature dependences of electric conductivity and thermoelectric power of some recently synthesized organic compounds, 4-tert-butylcalix[4]arene derivatives, are studied. Thin-film samples (d = 0.10-0.40 {mu}m) spin-coated from chloroform solutions onto glass substrates were used. Organic films with reproducible electron transport properties can be obtained if, after deposition, they are submitted to a heat treatment within temperature range of 295-575 K. The studied polycrystalline compounds show typical p-type semiconductor behavior. The activation energy of the electric conduction ranges between 0.82 and 1.12 eV, while the ratio of charge carrier mobilities was found in the range of 0.83-0.94. Some correlations between semiconducting parameters and molecular structure of the organic compounds have been discussed. In the higher temperature ranges (T > 420 K), the electron transport in examined compounds can be interpreted in terms of the band gap representation model, while in the lower temperature range, the Mott's variable-range hopping conduction model was found to be appropriate. The investigated compounds hold promise for thermistor applications. - Highlights: Black-Right-Pointing-Pointer 4-tert-butylcalix(4)arene derivatives in thin films are p-type semiconductors. Black-Right-Pointing-Pointer The electron transfer is favored by their extended conjugation and packing capacity. Black-Right-Pointing-Pointer The band gap representation is suitable in the higher temperature range. Black-Right-Pointing-Pointer The Mott's VRH conduction model may be applied in the lower temperature range. Black-Right-Pointing-Pointer As-prepared organic compounds are promising for thermistor applications.

Electron transport properties of some new 4-tert-butylcalix[4]arene derivatives in thin films

International Nuclear Information System (INIS)

Leontie, Liviu; Danac, Ramona; Girtan, Mihaela; Carlescu, Aurelian; Rambu, Alicia Petronela; Rusu, Gheorghe I.

2012-01-01

Temperature dependences of electric conductivity and thermoelectric power of some recently synthesized organic compounds, 4-tert-butylcalix[4]arene derivatives, are studied. Thin-film samples (d = 0.10–0.40 μm) spin-coated from chloroform solutions onto glass substrates were used. Organic films with reproducible electron transport properties can be obtained if, after deposition, they are submitted to a heat treatment within temperature range of 295–575 K. The studied polycrystalline compounds show typical p-type semiconductor behavior. The activation energy of the electric conduction ranges between 0.82 and 1.12 eV, while the ratio of charge carrier mobilities was found in the range of 0.83–0.94. Some correlations between semiconducting parameters and molecular structure of the organic compounds have been discussed. In the higher temperature ranges (T > 420 K), the electron transport in examined compounds can be interpreted in terms of the band gap representation model, while in the lower temperature range, the Mott's variable-range hopping conduction model was found to be appropriate. The investigated compounds hold promise for thermistor applications. - Highlights: ► 4-tert-butylcalix(4)arene derivatives in thin films are p-type semiconductors. ► The electron transfer is favored by their extended conjugation and packing capacity. ► The band gap representation is suitable in the higher temperature range. ► The Mott's VRH conduction model may be applied in the lower temperature range. ► As-prepared organic compounds are promising for thermistor applications.

Precipitation method for barium metaborate (BaB2O4) synthesis from borax solution

International Nuclear Information System (INIS)

Akşener, Eymen; Figen, Aysel Kantürk; Pişkin, Sabriye

2013-01-01

In this study, barium metaborate (BaB 2 O 4 , BMB) synthesis from the borax solution was carried out. BMB currently is used in production of ceramic glazes, luminophors, oxide cathodes as well as additives to pigments for aqueous emulsion paints and also β−BaB 2 O 4 single crystals are the best candidate for fabrication of solid-state UV lasers operating at a wavelength of 200 nm due to excellent nonlinear optical properties. In the present study, synthesis was carried out from the borax solution (Na 2 B 4 O 7⋅ 10H 2 O, BDH) and barium chloride (BaCI 2⋅ 2H 2 O, Ba) in the glass-batch reactor with stirring. The effect of, times (5-15 min), molar ratio [stoich.ration (1.0:2.0), 1.25:2.0, 1.5:2.0, 2.5:2:0, 3.0:2.0, 3.5:2.0,4.0:2.0, 5.0:2.0] and also crystallization time (2-6 hour) on the BMB yield (%) was investigated at 80 °C reaction temperature. It is found that, BMB precipitation synthesis with 90 % yield can be performed from 0.50 molar ration (BDH:Ba), under 80 °C, 15 minute, and 6 hours crystallization time. The structural properties of BMB powders were characterized by using XRD, FT-IR and DTA-TG instrumental analysis technique