Anucha Ruangphanit

Extraction of mobility degradation, effective channel length and total series resistance of NMOS at elevated temperature

This article describes the extraction of total series resistance, effective channel length and low field effective channel mobility degradation parameter at temperature in the range of 25°C–125°C of NMOS device. The relation of I<inf>DS</inf> and V<inf>GS</inf> in a linear region was used with a different of channel length. The procedure is based on the measurement of the transconductance characteristics of MOSFET in the linear region. The transconductance characteristics is determine for the several devices of difference drawn channel length. The results shows that, the effective channel length is increased in a range of 5×10⁻¹⁰ m/°C. The low field mobility degradation parameter is decreased by the factor of 0.733. The total series resistance is increased in the range of 1.4 Ω-µm/°C. The errors between the predicted model and measured of I<inf>DS</inf>&V<inf>GS</inf> in linear region is approximately 3 %

A Comparison of Cation Distribution and Valence State in Spinel Crystal Structure of Zinc and Nickel Ferrites Using the Synchrotron X-ray Absorption Spectroscopy (XAS) Analysis

In this work, the physical structure, magnetism and local structure of zinc and nickel ferrites (ZnFe2O4 and NiFe2O4) synthesized by typical sol-gel combustion method, were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The formation of the single phase cubic spinel crystal structure and the different values of crystallite size (D), interplanar distance (d) and lattice constant (a) for all ferrite samples were evaluated by the XRD data. The VSM measurement provides the characteristic magnetic hysteresis loop (M-H) for each sample which was found to be significantly different from each other. The chemical shifts in Zn, Ni and Fe K-edges XANES spectra indicate the existence of Zn2+, Ni2+ and Fe3+ ions in these ferrites. The EXAFS spectra analyses applied to track Zn, Ni and Fe cation distribution indicate the distinct character of spinel crystal structure of both ferrites. The results exhibit that zinc ferrite is a normal spinel, while the nickel ferrite is an inverse spinel. Moreover, these EXAFS spectra analyses reveal that the distances between metal ion (Zn2+ or Ni2+) to central oxygen ion and to Fe3+ ions in the opposite lattice site for each ferrite sample are unequal which highly affect its magnetism. The overall simulated results are one of the important evidence encouraging the explanation on the paramagnetism for ZnFe2O4 and the ferrimagnetism for NiFe2O4.

CaCu3Ti4O12 Ceramic Synthesized by Sonochemical-Assisted Process

CaCu3Ti4O12 powders were synthesized by sonochemical-assisted process via a precursor solution of calcium nitrate trihydrate, titanium isopropoxide and copper nitrate trihydrate. The reaction process was conducted with the assistance of intense sonication using Sonics Model VCX 750 until the completely precipitated product was reached, followed by calcinations process. The physical microstructures, morphologies of as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. From XRD observation, it is evident that CaCu3Ti4O12 ceramic could be obtained by this synthesis process. It was additionally revealed that its crystallization and particle size was strongly dependent on the reaction time and calcinations temperature.

Preparation and Properties of Lead Free Bismuth Sodium Titanate−Bismuth Zinc Titanate Ceramics

Lead-free piezoelectric ceramics based on (1–x)Bi 1/2 Na 1/2 TiO 3 – x Bi(Zn 1/2 Ti 1/2 )O 3 (x = 0.0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.30, 0.40, and 0.5) were obtained via solid-state processing techniques. The influence of BZT addition on BNT characteristics, sintering, microstructure and properties was investigated. A single perovskite phase with rhombohedral symmetry was obtained for Bi(Zn 1/2 Ti 1/2 )O 3 substitutions of up to 10 mole%. A small amount of BZT was effective for improving both sintering behavior and dielectric properties of BNT ceramics. Optimized dielectric properties were obtained for samples with a maximum density of ρ = 98.3% for the composition, x = 0.1.

Synthesis and Morphology Evolution of Lead-Free Piezoelectric K1/2Na1/2NbO3 Powder at Low Temperature

A synthetic route for modified solid state reaction has been developed for the synthesis of the perovskite phase of potassium sodium niobate, K1/2Na1/2NbO3 (KNN). Potassium oxalate monohydrate (K2C2O4.H2O) and sodium oxalate (Na2C2O4) were employed as a source of potassium and sodium, respectively. The formation of the K1/2Na1/2NbO3 phase was investigated as a function of calcination conditions by TG-DTA and XRD techniques. Morphology and particle size were determined via an SEM technique. It was found that the minor phases of Na2CO3 and K2CO3 tend to form together with K1/2Na1/2NbO3, depending on calcination conditions. The perovskite phase was successfully synthesized at a low temperature of 400°C. As calcination temperatures increased from 600° to 850°C, the KNN solid solution became more homogeneous, XRD peaks became narrower, and a pattern similar to that expected for orthorhombic K1/2Na1/2NbO3 was achieved after 600°C, as indicated by the separate peaks of 0 2 2 and 2 0 0.

Synthesis, Characterization and Multiferroic Properties of Ni0.5Zn0.5Fe2O4-K0.5Na0.5NbO3 Nanocomposites

In this work, nanocrystalline lead-free multiferroic composites of nickel zinc ferrite (Ni0.5Zn0.5Fe2O4) – potassium sodium niobate (K0.5Na0.5NbO3) were synthesized by a sol-gel combustion method. The influence of Ni0.5Zn0.5Fe2O4 content, on the crystal structure, chemical bonding, morphologies, dielectric properties and magnetic behavior of K0.5Na0.5NbO3 was investigated using X-ray diffraction measurement, Raman spectroscopy, scanning electron microscope, LCR meter and vibrating sample magnetometer, respectively. The overall characterization results indicate that the various contents of ferrite and ferroelectric materials in those composites have a significant influence on their multiferroic properties. In addition, this method is proven as one of an ordinary, fast and efficacious way to synthesize functional multiferroic materials with simple availability implements.

Sol-gel Combustion Synthesis and Characterizations of Nanocrystalline Zinc, Nickel and Nickel-Zinc Ferrites

In this work, X-ray diffraction (XRD), Raman spectroscopy (RAMAN) and vibrating sample magnetometer (VSM) measurements were employed to investigate the crystal structure, chemical bonding and magnetic properties of the nanocrystalline Zinc, Nickel and Nickel-Zinc ferrites (ZnFe2O4, NiFe2O4 and Ni0.5Zn0.5Fe2O4) which were synthesized by sol-gel combustion method. Moreover, the composition of elements and the electronic structure including the cation distribution for all ferrite samples were examined through synchrotron X-ray fluorescence (XRF) and X-ray absorption near-edge structure (XANES) spectra. The overall characterization results indicate that the different amount of zinc and nickel ions in ferrites has crucial effect on their physical, magnetism and the site occupancy distribution of Fe3+ ions.

Structure and Dielectric Properties of Bi0.5K0.5TiO3-SrTiO3 Lead-Free Ceramics

Bismuth potassium titanate – strontium titanate (1-x)Bi0.5K0.5TiO3-(x)SrTiO3 (BKT-ST) lead-free ceramics when x = 0-0.20 were synthesized by the solid state reaction method with normal sintering. The ferroelectric phase transition was studied by X-ray diffraction (XRD). All compositions showed a single phase perovskite structure with tetragonal symmetry at room temperature and the phase structure transformed from ferroelectric tetragonal – paraelectric cubic in the range of x ³ 0.10 . Dielectric study revealed that the dielectric relaxor behavior was induced with increasing ST and transition temperature (Tm@εr max) of ST-doped BKT had a tendency to decrease with increasing ST. The Bi0.5K0.5TiO3 – SrTiO3 system was expected to be a new and promising candidate for lead-free capacitors.

Facile Synthesis of Lead-Free Piezoelectric Sodium Niobate (NaNbO3) Powders via the Solution Combustion Method

Nanocrystalline perovskite sodium niobate, NaNbO3 (NN), was prepared by means of the glycine-nitrate combustion process (GNP). This was achieved by using sodium nitrate and niobium pentoxide as starting materials. The X-ray diffraction technique (XRD) was used to investigate the phase formation and purity of synthesized powder. The morphology of the powder obtained was characterized using a scanning electron microscope (SEM). The amount of glycine in the starting solution was found to have significant influence on the combustion process and the final phase purity. The fuel-rich ratio (fuel-to-oxidant molar ratio of 1.0) was found to produce NaNbO3 powder of an average crystalline size (defined by XRD) of 31.31 ± 4.37 nm. Calcination at 400°C for 4 h produced single phase NN with an average crystalline size of about 26.60 to 37.14 nm.