Effect of ceramic oxide on PVC-PMMA hybrid polymer electrolytes

The preparation and characterization of PVC-PMMA-LiBF₄/LiAsF₆-DBP composite polymer electrolytes for different concentrations of ZrO₂ have been investigated. FTIR studies indicate complex formation between the polymers, salt and plasticizer. The electrical conductivity values measured by ac impedance spectroscopy were found to depend upon the ZrO₂ concentration. The temperature dependence of the conductivity of the polymer films seems to obey the VTF relation. The conductivity values are presented and the results are discussed.     

Characterization of nanocomposite polymer electrolyte based on P(ECH-EO)

ZrO₂ nanoparticles have been prepared by poly acrylamide gel route. The synthesized nanosized ZrO₂ have been incorporated into plasticized polymer electrolyte (PPE), P(ECH-EO): LiClO₄: γ-BL system to understand the effect of ZrO₂ on the ionic conductivity. The X-ray diffraction pattern of the synthesized ZrO₂ nanoparticles reveals the crystalline phase. The X-ray diffraction patterns of P(ECH-EO) based NCPEM confirm the polymer-salt-nanoparticle complexation. The scanning electron microscope image of NCPEM confirms that the ZrO₂ nanoparticles were distributed uniformly in the polymer matrix. The presence of nano filler has increased the ionic conductivity and the maximum dc conductivity value is found to be 6.24×10⁻⁶ S cm⁻¹ at 303 K for 96(PPE): 4ZrO₂ (mol%).     

Ionic conductivity studies in composite solid polymer electrolytes based on methylmethacrylate

The preparation and characterization of composite polymer electrolytes of PMMA-LiClO₄-DMP for different concentrations of CeO₂ have been investigated. FTIR studies indicate complex formation between the polymer, salt and plasticizer. The electrical conductivity values measured by a.c. impedance spectroscopy are found to depend upon the CeO₂ concentration. The temperature dependence of the conductivity of the polymer films seems to obey the VTF relation. The conductivity values are presented and the results are discussed.     

3ω法加热/测温膜中温度波解析及其在微/纳米薄膜导热系数测量中的应用

给出了3ω法测试系统中描述薄膜表面加热/测温膜中温度波动的级数形式解，并将复数温度波动的实部和虚部分开表示.利用该解分析了交流加热频率、加热膜宽度和材料热物性的组合参数对加热膜温度波动幅度的影响.并根据此解对测量原理的数学模型进行了修正，建立了相应的3ω测试系统，首先测定了厚度为500 nm SiO₂薄膜的导热系数，验证了实验系统的合理性.加大了测试频率，利用级数模型在高频段直接得到SiO₂薄膜的导热系数，结合低频段的数据同时确定了Si基体的导热系数.利用级数解分析测试了激光晶体Nd:YAG〈111〉面上多层ZrO₂/SiO₂增透膜的导热系数，测试的ZrO₂薄膜的导热系数比体材料小.进行了不确定度分析.结果表明，提出的分析方法可以有效研究微器件表面薄膜结构的导热性能. 关键词： ω法')" href="#">3ω法 微/纳米薄膜 导热系数 微尺度加热膜     

Two-band conductivity of ZrO<Subscript>2</Subscript> synthesized by molecular beam epitaxy

Using experiments on the injection of minority carriers from n-and p-type silicon, the contribution of electrons and holes to the conductivity of ZrO₂ in the Si/ZrO₂/Al structure is determined. It is found that electrons and holes make a contribution to the conductivity of ZrO₂, so that ZrO₂ exhibits two-band conductivity.     

Study of phase transition in ZrO2 doped with Pb3O4

Electrical conductivity of ZrO₂ doped with Pb₃O₄ has been measured at different temperatures for different molar ratios (x=0, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06). The conductivity increases due to migration of vacancies, created by doping. The conductivity increases with increase in temperature till 180 °C and thereby decreases due to collapse of the fluorite framework. A second rise in conductivity at higher temperatures beyond 500-618 °C is due to phase transition of ZrO₂. DTA and X-ray powder diffraction were carried out for confirming doping effect and transition in ZrO₂.The addition of Pb₃O₄ to ZrO₂ shifted the phase transition of ZrO₂ due to the interaction between Pb₃O₄ and ZrO₂.     

Effect of HPC and Water Concentration on the Evolution of Size,Aggregation and Crystallization of Sol-gel Nano Zirconia

Nano-sized zirconia (ZrO₂) powder is synthesized using sol-gel technique involving hydrolysis and condensation of zirconium(IV) n-propoxide in an alcohol solution, utilizing hydroxypropyl cellulose (HPC) polymer as a steric stabilizer. It is demonstrated that ZrO₂ nanoparticle size can be reduced using high R-value (defined as the ratio of molar concentrations of water and alkoxide). It is also shown that ZrO₂ nanoparticle size can be reduced further by synthesizing these particles in the presence of HPC polymer. The agglomeration tendency of ZrO₂ nanoparticles is demonstrated to decrease due to the steric hindrance created by the adsorbed polymer. The nanocrystallite size and their 'hard-aggregates' formation tendency are observed to affect the high temperature metastable tetragonal phase stabilization at room temperature within ZrO₂ particles.     

Zirconia based oxide ion conductors for solid oxide fuel cells

The electrical conductivity in the ZrO₂-Ln₂O₃ and ZrO₂-MO₂-Ln₂O₃(M = Hf, Ce, Ln = lanthanides) systems has been examined.The highest conductivity of 0.3 S/cm at 1000 °C was found in the ZrO₂-Sc₂O₃ system. The addition of MO₂ into the ZrO₂-Ln₂O₃(Ln = Sc, Y, Yb) systems showed the conductivity decreasing. The conduction mechanism in the zirconia based oxide ion conductors was discussed in view of the dopant ionic radius. The aging effect of the conductivity in the ZrO₂-Ln₂O₃ systems has been measured in a temperature rang 800–1000 °C. ZrO₂ with a high content of Ln₂O₃ showed no significant conductivity degradation. Paper presented at the 97th Xiangshan Science Conference on New Solid State Fuel Cells, Xiangshan, Beijing, China, June 14–17, 1998.     

ZrO2涂层热性质的弧光光热分析技术和有限差分热流模型研究

应量汞弧光灯作加热光源的背表面检测光热技术和有限差分热流模型研究了ＺｒＯ₂涂层的热导和热扩散率。其值分别为：ｋ＝０．００６９Ｊ／ｃｍ·Ｋ·ｓ和α＝０．００２８ｃｍ²／ｓ．结果表明对于带涂层的多层系统的光热检测，有限差分热流模型法是一个有效的数据处理方法。 关键词：     

Study of electrical conductivity changes and phase transitions in Co3O4 doped ZrO2

The electrical conductivity of ZrO₂ doped with Co₃O₄ has been measured at various temperatures for different molar ratios. The conductivity increases due to the migration of vacancies created by doping. The conductivity is also found to increase with rise in temperature up to 120°C, and after attaining a maximum the conductivity decreases due to a collapse of the lattice framework. A second rise in conductivity around 460°C in all the compositions confirms the phase transition in ZrO₂ from monoclinic to tetragonal symmetry. X-ray powder diffraction and DTA studies were carried out for confirming the doping effects and the transition in ZrO₂.     

Horizontally networked carbon nanotubes grown on Au–Fe catalyst nanoparticles

Undoped and doped indium tin oxide (ITO) with different concentrations (2, 4, and 6 mol%) of different dopants (CuO, Cr₂O₃, and ZrO₂) were prepared in the nano-size scale (19–33 nm) using Pechini method. The thermal decomposition of the precursors was studied. The electrical properties of all the prepared samples were investigated. All the investigated systems have higher conductivity than that of ITO. For ITO doped with CuO, as the concentration of CuO increases, the conductivity increases. The highest conductivity was obtained for ITO doped with 6 mol% of CuO. For ITO doped with Cr₂O₃, as the concentration of Cr₂O₃ increases the conductivity increases and above 4 mol% Cr₂O₃ the conductivity decreases. For ITO doped with ZrO₂, as the ZrO₂ concentration increases, the conductivity increases up to 4 mol% of ZrO₂ and then decreases. The band gap was detected for all the investigated systems.     

FTIR and conductivity studies of PVC based polymer electrolyte systems

Poly (vinylchloride) (PVC)-LiBF₄ polymer electrolytes plasticized with DBP in different mole ratios have been studied by FTIR and Impedance Spectroscopic techniques. The complexation has been confirmed from FTIR studies. The maximum room temperature conductivity (2.1·.10⁻⁷ S·.cm⁻¹) has been observed for PVC-LiBF₄-DBP (10-5-85 mole%) complex. The temperature dependence of the conductivity of the polymer films seems to obey the VTF relation. The conductivity values are presented and the results are discussed.     

Conductivity behaviour of a cubic/tetragonal phase stabilized nanocrystalline La2O3-ZrO2

La₂O₃ doped nanocrystalline zirconia (ZrO₂) was prepared by chemical co-precipitation method for the 3, 5, 8, 10, 15, 20 and 30 mol.% concentrations of La₂O₃. Structural studies were performed using X-ray diffraction (XRD). All the as-synthesized samples were found to be in monoclinic phase. As-synthesized samples were given heat treatment at higher temperatures for tetragonal/cubic structural phase stabilization. Sintering the samples at temperature 1173 K stabilized the tetragonal and cubic phases. A slight shift in the 100% peak of the cubic phase was observed towards the low diffraction angle indicating the substitution of the bigger La³⁺ ion into the ZrO₂ lattice. Grain sizes were found to lie between 10 and 13 nm. Electrical conductivity studies were performed on the cubic phase stabilized La₂O₃-ZrO₂ by complex impedance spectroscopy. The conductivity increases up to the dopant concentration 10 mol.% and then decreases with further increase in La₂O₃ concentration. Initial increase in conductivity is correlated to the stabilization of the cubic phase and the subsequent decrease in the conductivity with the dopant content is interpreted on the basis of the oxygen-ion movement model. Electrical conductivity has contributions from grain and grain boundary regions. But the grain boundary conductivity is slightly higher than the corresponding grain conductivity. Higher grain boundary conductivity shows higher diffusion coefficient for the atoms on the surface of the ZrO₂ grains. The possible mechanism of the oxygen ion conduction in the La₂O₃ stabilized zirconia (LSZ) is reported. The Barton, Nakajima and Namikawa (BNN) relation has been applied to the conductivity data and found that the d.c. and a.c. conductions have been correlated to each other by the same mechanism.     

The role of zirconium oxide as nano-filler on the conductivity,morphology, and thermal stability of poly(methyl methacrylate)–poly(styrene-co-acrylonitrile)-based plasticized composite solid polymer electrolytes

The plasticized composite solid polymer electrolytes (CSPE) involving polymer blends poly(methyl methacrylate)-poly(styrene-co-acrylonitrile) (PMMA-SAN), plasticizers ethylene carbonate (EC), and propylene carbonate (PC) with lithium triflate (LiCF₃SO₃) as salt and varying concentration of composite nano-filler zirconium oxide (ZrO₂) is prepared by solution casting technique using THF as solvent. The powder X-ray diffraction (XRD) studies reveal amorphous nature of the CSPE samples. Fourier transform infrared (FT-IR) spectroscopy studies reveal interaction of Li⁺ ion with plasticizers, both C=O and OCH₃ group of the PMMA, while nitrile group of SAN is inert. AC impedance and dielectric studies reveal that the ionic conductivity (σ), dielectric constant (ε’), and dielectric loss (ε”) of the prepared CSPE samples increase with increasing content of ZrO₂ nano-filler up to 6 wt% and decrease with further additions. The temperature dependence of ionic conductivity follows Arrhenius relation and indicates ion-hopping mechanism. The sample Z2 (6 wt% ZrO₂) with relaxation time τ of 8.13?×?10^–7 s possess lowest activation energy (E_a?=?0.23 eV) and highest conductivity (2.32?×?10^–4 S cm^?1) at room temperature. Thermogravimetric analysis (TGA) reveals thermal stability of highest conducting sample Z2 up to 321 °C after complete removal of residual solvent, moisture, and its impurities. Differential scanning calorimetric (DSC) studies reveal absence of glass transition temperature (T_g) corresponding to atactic PMMA for the CSPE Z2, while isotactic PMMA component shows T_g around 70 °C, which is due to increased interaction of filler with PMMA leading to change in its tacticity. Scanning electron microscopy (SEM) analysis reveals blending of PMMA/SAN polymers and lithium triflate salt. The incorporation of nano-filler ZrO₂ leads to change in surface topology of polymer matrix. Rough surface of the CSPE Z2 leads to new pathway for ionic conduction leading to maximum ionic conductivity.     

The effect of alumina addition on the conductivity, microstructure and mechanical strength of zirconia — yttria electrolytes

The effect of alumina additions on the ionic conductivity and mechanical properties of 3 and 8 mol% Y₂O₃ - ZrO₂ compositions has been investigated. Such materials are of interest for use in fuel cells and other similar applications. Sintered specimens were characterised by XRD, SEM, impedance spectroscopy, four — probe DC conductivity and mechanical strength measurements. Alumina additions had no affect on the conductivity degradation behaviour at 1000 °C and the activation energy but resulted in an increase in the strength of 8 mol% Y₂O₃ - ZrO₂ composition by about 25%. However, a significant drop in the ionic conductivity well above what could be accounted for by the decrease in the volume fraction of the conducting phase, was observed.     

AC impedance, FTIR and XRD investigations of poly acrylonitrile complexed with LiCF3SO3

Solid polymer electrolytes of high ionic conductivity are prepared using poly acrylonitrile (PAN), propylene carbonate (PC), ethylene carbonate (EC) and LiCF₃SO₃. The polymer films are characterised by X-ray diffraction, FTIR and a.c. impedance spectroscopic techniques. The conductivity studies of PAN-LiCF₃SO₃-PC-EC polymer electrolyte systems are carried out in the temperature range 301–373 K. The temperature dependence of the conductivity of the polymer films obeys the VTF relation. The conductivity values are presented and the results are discussed.     

Phase composition, microstructure and electrical properties of alumina-zirconia eutectic composites

Oxide eutectic composites prepared by a directional solidification are noticeable for their good mechanical properties and high temperature stability in oxidizing environments. In this paper we study the influence of stabilizers (Y, Sc) on the phase composition, microstructure and electrical properties of Al₂O₃ - ZrO₂ eutectic composites. At a hypereutectic composition of the melt, we have prepared the composites with tetragonal ZrO₂, which possesses conductivities comparable to those of the composites containing cubic ZrO₂. An addition of Sc₂O₃ improves the ionic conductivity of the Al₂O₃ - (Y₂O₃)ZrO₂ eutectic composite at high temperatures. Both the microstructure and ionic conductivity do not change along the composite (grown at a constant growth rate). Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16–22, 2001.     

The transport and thermal properties of glassy LiPO<Subscript>3</Subscript>/crystalline Al<Subscript>2</Subscript>O<Subscript>3</Subscript> (ZrO<Subscript>2</Subscript>) composite electrolytes

Glassy LiPO₃/crystalline Al₂O₃ and glassy LiPO₃/crystalline ZrO₂ (0–12.5 vol.% of oxide fillers) composite solid electrolytes have been prepared by glass matrix softening. Their thermal and transport properties have been investigated by differential scanning calorimetry (DSC) and impedance spectroscopy methods. The addition of ZrO₂ leads to a decrease in the crystallization temperature of LiPO₃ glass. It was found that the conductivity behavior depends on the nature of the dispersed addition. In the case of the Al₂O₃ addition, the increase in the electrical conductivity is observed. The ionic conductivity of the LiPO₃/10% Al₂O₃ composite reaches 5.8 × 10^?8 S/cm at room temperature. In contrast, the conductivity in the LiPO₃/ZrO₂ composite system decreases.     

Structural ordering and chemical stability of a complex perovskite oxide DyBa2ZrO5.5 with YBa2Cu3O7-δ superconductors

2 ZrO_5.5 has been synthesized by solid-state reaction. Structural ordering in this material has been studied by X-ray diffraction (XRD). The XRD spectra reveal that DyBa₂ZrO_5.5 has an ordered complex cubic perovskite structure. The presence of superstructure reflections in the XRD spectra is characteristic of A₂BB’O₆-type crystalline structure. The chemical stability of DyBa₂ZrO_5.5 with YBa₂CuO_7-δ (YBCO) superconductors has been studied by XRD and electrical resistivity measurements. These studies show that DyBa₂ZrO_5.5 is chemically stable with YBCO and there is no degradation in the superconducting transition temperature T_c of YBCO even when mixed up to 1:1 vol%, with DyBa₂ZrO_5.5 in YBCO. Detailed study of the superconducting transition region shows that T_c(onset) and T_c(0) values of pure YBCO and YBCO–DyBa₂ZrO_5.5 composites are similar in both cases. The implications are discussed. Accepted: 13 October 1997     

Investigations on PMMA-PVdF polymer blend electrolyte with esters of dibenzoic acids as plasticizers

Plasticizers can be used to change the electrical and mechanical properties of polymer electrolytes by reducing the degree of crystallinity and lowering the glass transition temperature. The transport properties of gel type ionic conducting membranes consisting of poly (methyl methacrylate) (PMMA), poly (vinylidene fluriode) (PVdF), Lithium perchlorate (LiClO₄) and dioctyl phthalate (DOP), dibutyl phthalate (DBP), dimethyl phthalate (DMP) or diethyl phthalate (DEP) were studied. The polymer films were characterized by X-ray diffraction, Thermal, Fourier transform infrared and impedance spectroscopic studies. It is found that the addition of DMP as the plasticizer in the PMMA / PVdF-LiClO₄ polymer complex favours an enhancement in ionic conductivity. The temperature dependence of the conductivity of the polymer films seems to obey the VTF relation. The conductivity values are presented and the results are discussed.