Electrical Properties Of Thick Films Research Articles

Lithium La0.57Li0.33TiO3 Perovskite and Li1.3Al0.3Ti1.7(PO4)3 Li-NASICON Supported Thick Films Electrolytes Prepared by Tape Casting Method

In this work, thick films of Perovskite La0.57Li0.33TiO3 (LLTO) and Li-NASICON Li1.3Al0.3Ti1.7(PO4)3 (LATP) Li-conductors have been prepared by tape casting and their microstructure and homogeneity assessed by SEM and confocal Raman spectroscopy. Electrical properties of thick films have been investigated by Impedance spectroscopy. In particular, bulk, grain-boundary and electrode contributions to conductivity have been differentiated as a function of frequency. However, modifications on the grain-boundary chemistry affects considerably ion conductivity of films. The confocal Raman spectroscopy results allowed the observation of the resulting phases particles connectivity in thick films and a better understanding of ionic conductivity results in relation with the samples heterogeneity. In LLTO films, the reactivity of the film particles against water leads to formation of hydroxyl groups that decreases the Li mobility at the particles surface after sintering. In LTAP films the formation of a high conducting grain-boundary phase leads to improve total conductivity values making thick films promising candidates for application in all solid state Li secondary batteries.

알루미나 기판에 스크린 프린팅된 Ag(Ta,Nb)O3후막의 유전특성 및 초고주파 특성에 대한 연구

Perovskite niobates and tantalates have been placed on a short list of functional materials for future technologies. This article was investigated ferroelectric materials <TEX>$Ag(Ta,Nb)O_3$</TEX> thick film. In this study, we have fabricated the <TEX>$Ag(Ta,Nb)O_3$</TEX> thick film on the <TEX>$Al_2O_3$</TEX> substrates by screen printing method. The <TEX>$Ag(Ta,Nb)O_3$</TEX> thick film were fabricated by the mixed oxide method. The sintering temperature and time were 1,150<TEX>$^{\circ}C$</TEX>, 2 hr. The electrical properties of <TEX>$Ag(Ta,Nb)O_3$</TEX> thick film were investigated at 30~100<TEX>$^{\circ}C$</TEX>.

Influence of Mn 2+ on the electrical properties of textured KNN thick films

Textured K 0.5Na 0.5NbO 3 thick film was prepared by the reactive templated grain growth method. The effects of Mn 2+ doping on the phase structure, microstructure and electrical properties of the K 0.5Na 0.5NbO 3 textured thick film were investigated. The grain orientation degree decreased with increasing Mn 2+ and reduced to 50% for the thick film with 5 mol% Mn 2+. The addition of Mn 2+ improved the microstructure of the thick film. The electric properties of the thick film were also enhanced because of the high densification, the vacancy compensation effect and the acceptor doping effects of Mn 2+. The K 0.5Na 0.5NbO 3 thick film with 2 mol% Mn 2+ doping possessed the optimum properties: P r = 3.05 μC/cm 2, E c = 4.79 kV/cm, J = 4.6 × 10 −6A/cm 2 (at 25 kV/cm) and d 33 * = 124 pm/V .

Improvement in ferroelectric properties of PZT thick films prepared by a modified sol–gel technique using low temperature laser annealing

Low temperature continuous-wave CO2 laser annealing technique was successfully adopted to fabricate ferroelectric Pb(Zr0.52Ti0.48)O3(PZT) thick films of different thickness on a Pt/Ti/SiO2/Si substrate using powder-mixing and sol–gel spin coating process. X-ray diffractometer (XRD) results showed that laser annealing provides an extremely efficient way to crystallize the materials. Films of type-I with thickness of 5 μm showed cracks and rough surface morphology, indicating the importance of controlling interfacial stress and choosing appropriate size of the mixing powders. Better microstructure was observed in the type-II films. Type-II PZT film 5 μm thick and annealed at 121 W cm2 exhibited better ferroelectric properties (Pr = 15.86 μ C cm2) compared to type-I PZT film. The results indicated that porosity and electrical properties of thick films can be controlled using appropriate processing parameters, suggesting the applicability of continuous-wave CO2 laser annealing in the fabrication of PZT films.

Low-temperature processing of sol-gel derived Pb(Zr,Ti)O3 thick films using CO2 laser annealing

Fabrication of ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thick films on a Pt/Ti/SiO2/Si substrate using powder-mixing sol-gel spin coating and continuous wave CO2 laser annealing technique to treat the specimens with at a relatively low temperature was investigated in the present work. PZT fine powders were prepared by drying and pyrolysis of sol-gel solutions and calcined at temperatures from 400 to 750°C. After fine powder-containing sol-gel solutions were spin-coated on a substrate and pyrolyzed, CO2 laser annealing was carried out to heat treat the specimens. The results show that laser annealing provides an extremely efficient way to crystallize the materials, but an amorphous phase may also form in the case of overheating. Thicker films absorb laser energy more effectively and therefore melt at shorter periods, implying a significant volume effect. A film with thickness of 1 μm shows cracks and rough surface morphology and it was difficult to obtain acceptable electrical properties, indicating importance of controlling interfacial stress and choosing appropriate size of the mixing powders. On the other hand, a thick film of 5 μm annealed at 100 W/cm2 for 15 s exhibits excellent properties (P r = 36.1 μC/cm2, E c = 19.66 kV/cm). Films of 10 μm form a melting zone at the surface and a non-crystallized bottom layer easily at an energy density of 100 W/cm2, showing poor electrical properties. Besides, porosity and electrical properties of thick films can be controlled using appropriate processing parameters, suggesting that CO2 laser annealing of modified sol-gel films is suitable for fabricating films of low dielectric constants and high crystallinity.

Effects of the Particle Size and the Firing Atmosphere on Electrical Properties in PNN-PZT Thick Films

Pb(Ni 1/3 Nb 2/3 )O3─PbZrO3─PbTiO3 (PNN-PZT) thick films were screen-printed on platinized alumina substrates and fired at 800–1000°C under PbO atmosphere or in air. Effects of the starting particle size and the firing atmosphere on the microstructure and electrical properties of the thick films were investigated. Attrition milling produced smaller particle size than ball milling. Thick films prepared from attrition-milled powders showed more uniform microstructure at all firing temperatures and also denser microstructure and better electrical properties at firing temperature above 900°C than thick films prepared from ball-milled powders. PbO atmosphere improved electrical properties of thick films prepared from attrition-milled powders while little influenced on those of thick films prepared from ball-milled powders. Electrical properties of the thick film prepared from attrition-milled powders and fired at 900°C under PbO atmosphere were as follows: dielectric constant of 604, remanent polarization of 17.4 μ C/cm2 and coercive field of 60.6 kV/cm.

Electrical properties of screen printed BaTiO 3 thick films

The deposition of thick film pastes by screen-printing is a relatively simple and convenient method to produce thicker layers with thickness up to 100 μm. In the present work, the barium titanate thick films were prepared from mechanically activated powders based on BaCO 3 and TiO 2. After mixing, the powders were calcined at low temperature by slow heating and cooling rates. The thick films were deposited on to Al 2O 3 substrates through hybrid technology. The obtained films were fired at 850 °C together with electrode material (silver/palladium). The electrical properties of thick films: dielectric permittivity, dielectric losses, Curie temperature, hysteresis loop were reported. The obtained BT thick films can be applied in as multilayer capacitors or in gas sensor application.

Thick films of MgFe 2O 4 for humidity sensors

In this paper the humidity-sensitive electrical properties of MgFe 2O 4 thick-films are studied. Thick films were prepared by screen printing on alumina substrates and subsequent firing. Pastes for screen printing were obtained by adding an organic vehicle and Bi 2O 3, as a sintering aid, to MgFe 2O 4 powders. The microstructure of the films was varied using MgFe 2O 4 powders with different grain sizes and by changing the firing temperatures. The microstructure of the films was studied by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), and Hg porosimetry. The humidity-sensitive electrical properties of thick films were tested by electrochemical impedance spectroscopy (EIS). D.C. measurements were made to test reproducibility and time response, and to study the conduction mechanism. The electrical response of the films was correlated with their microstructure and the distribution of Bi 2O 3 in the films.

Structural and electrical properties of screen-printed thick films of YBa 2Cu 3O 7 − x superconductors

Screen-printed thick films of the ceramic oxide superconductor material YBa 2Cu 3O 7 − x have been prepared on alumina substrates. A buffer layer of glass between the substrate and the oxide film has been used to promote adhesion as well as to decrease the reaction between the substrate and the film and thus to prevent “poisoning” of the superconducting thick film. Structural and electrical properties of the thick films have been studied. The sintered films show an orthorhombic structure with columnar growth with an oriented c axis. The films exhibit onset of superconductivity at 82 K with a 2 K transition width and a critical current density of 100 A cm −1 at 77 K.

Heteroepitaxial GaAs on Aluminum Oxide: The Formation and Electrical Properties of Zn‐ and Cd‐Doped Films

An all metalorganic‐hydride chemical vapor deposition process has been used to produce p‐type films on sapphire. Dimethylcadmium or di-ethylzinc have been combined with trimethylgallium and arsine to produce films with net acceptor concentrations as high as and , respectively. The doping concentrations are found to be an exponential function of growth temperature when other parameters remain fixed. The electrical properties of thick films are found to be equivalent to good quality bulk . Hole mobilities approximately 80–90% of the best thick‐film values have been obtained for acceptor concentrations ∼1019 cm−3 in thin (∼1 pm) films on sapphire and spinel.