KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 10 of 15

Some of the metrics are blocked by your
consent settings
Lead-free (Ba,Ca)(Ti,Zr)O3 ceramics within the polymorphic phase region exhibiting large, fatigue-free piezoelectric strains
(2017-11-05)
Chaiyo, Nopsiri
;
Cann, David P.
;
Vittayakorn, Naratip
Lead-free xBaZrO<inf>3</inf>-(0.85-x)BaTiO<inf>3</inf>-0.15CaTiO<inf>3</inf>; x = 0.00–0.20 (xBZ) ceramics were prepared successfully using the conventional solid-state reaction method. Unipolar electric-field-induced strains of the composition x = 0.125 in the polymorphic phase region (PPR) composition show an extraordinarily high normalized piezoelectric coefficient (d<inf>33</inf>⁎) of 2244 pm/V with relatively low hysteresis at a low electric field of 5 kV/cm, which is higher than that of most reported lead-free ceramics. The PPR composition also exhibits excellent fatigue resistance to bipolar electric cycling with negligible loss of electric-field-induced strain after 106 cycles. A two-phase mixture model featuring short-range ordering, which is dispersed in the long-range ferroelectric phase, is proposed to explain the outstanding piezoelectric properties. The reversible electric-field-induced phase transition between the two states is responsible for the large normalized piezoelectric coefficient and fatigue resistance. Under repeated electric cycling, the domains become more dynamic, and the change in domain configuration becomes easier due to decreased energy requirement upon polarization reversal. Furthermore, the ceramic shows single crystal-like behavior characterized by a nearly vertical slope in the polarization hysteresis data, which correlates to the electric field induced transformation from a multi-domain state to a single-domain state. This environmentally benign lead-free ceramic, with outstanding properties, has great potential use for highly responsive and reliable actuators.
Some of the metrics are blocked by your
consent settings
Effects of BiMO3 on dielectric, ferroelectric, and piezoelectric properties of perovskite lead-free piezoelectric BaTiO3–(Bi0.5Na0.5)TiO3 ceramics
(2017-07-01)
Chaiyo, Nopsiri
;
Muanghlua, Rangson
;
Vittayakorn, Wanwilai
;
Vittayakorn, Naratip
New lead-free piezoelectric ceramics of 0.9BaTiO<inf>3</inf>–(0.1−x)(Bi<inf>0.5</inf>Na<inf>0.5</inf>)TiO<inf>3</inf>–xBiMO<inf>3</inf>, M=Al and Ga, where x=0.00-0.10, were fabricated by the solid-state reaction technique. The effect of BiMO<inf>3</inf> contents on the perovskite structure, phase transition, and dielectric, ferroelectric, and piezoelectric properties was investigated. X-ray diffraction patterns showed that the ceramics exhibit a monophasic perovskite phase up to x=0.06, suggesting stabilized perovskite structures with B-site aliovalent substitutions. Compositional-dependent phase transitions were observed from tetragonal to pseudo-cubic phase with increasing BiMO<inf>3</inf> amounts. Al3+ ions were found to stabilize the transition temperature of the ceramics, while significantly decreasing transition temperature, and a change in the dielectric peak were found with an increasing amount of Ga3+. Regarding Al3+ substitution, the remanent polarization (P<inf>r</inf>) values were found to decrease slightly with the Al3+ amount. With regard to Ga3+ substitution, P<inf>r</inf> values decreased with the Ga3+ amount up to 0.06 and then increased slightly. The ceramics became softer with a higher degree of substitution according to the lower coercive field (E<inf>c</inf>), when compared with 0.9BaTiO<inf>3</inf>–0.1(Bi<inf>0.5</inf>Na<inf>0.5</inf>)TiO<inf>3</inf> ceramics. Ceramics with a lower degree of substitution and tetragonal phase showed butterfly strain loops that correlated with normal ferroelectric behavior.
Some of the metrics are blocked by your
consent settings
Phase transitions, ferroelectric, and piezoelectric properties of lead-free piezoelectric xBaZrO3–(0.25−x)CaTiO3–0.75BaTiO3 ceramics
(2015-09-25)
Chaiyo, Nopsiri
;
Cann, David P.
;
Vittayakorn, Naratip
Lead-free xBaZrO<inf>3</inf>–(0.25−x)CaTiO<inf>3</inf>–0.75BaTiO<inf>3</inf>; x = 0.00–0.25 ceramics were successfully prepared using the conventional solid-state reaction method. Analysis of the sintered ceramics showed that all compositions exhibited a pure phase perovskite. The effects of composition on the phase transition, ferroelectric properties, and piezoelectric properties were studied. With the increasing BaZrO<inf>3</inf> content, the phase transition temperature (T<inf>C</inf>) decreased and the coercive field E<inf>c</inf> decreased. The phase diagram featuring a cubic–rhombohedral–tetragonal triple point (x ~ 0.125) was derived from X-ray diffraction data and dielectric data as a function of temperature. Compositions near the convergence region exhibited the maximum peak in permittivity of ~11,400 at T<inf>C</inf>. In addition, the morphotropic phase boundary compositions showed an enhancement in ferroelectric and piezoelectric properties. The composition 0.125BaZrO<inf>3</inf>–0.125CaTiO<inf>3</inf>–0.75BaTiO<inf>3</inf> exhibited the highest strain values of 0.14 % and a d<inf>33</inf>* of 474 pm/V.
Some of the metrics are blocked by your
consent settings
Synthesis and characterization of thermochromic la 0.75 Ca 0.25MnO3 perovskite manganites nano-powders by microwave-assisted solution combustion synthesis
(2014-01-02)
Kahatta, Sagulthai
;
Techitdheera, Wicharn
;
Chaiyo, Nopsiri
;
Pecharapa, Wisanu
;
Vittayakorn, Naratip
The microwave-assisted solution combustion synthesis was developed for application with initially synthesized thermochromic perovskite manganese oxide La0.75Ca0.25MnO<inf>3</inf> nano-powders. Dry and very fine powders were obtained after one-step combustion reaction for less than 10 min in a modified domestic microwave oven. The thermal behavior, phase formation and purity of the precursor, and as-synthesized and calcined powders, were investigated by TGA/DTA, X-ray diffraction (XRD) and FT-IR techniques. The morphology of the powder obtained was characterized using a scanning electron microscope (SEM). The XRD pattern and FT-IR results showed that as-synthesized La <inf>0.75</inf>Ca<inf>0.25</inf>MnO<inf>3</inf> powders were crystalline, and the monophasic perovskite phase occurred with an average crystallite size of 30.46 ± 5.54 nm for 6 h at a relatively low calcination temperature of 900°C. The small particle size obtained by SEM suggested a high specific surface area and high sinterability. This method was found to be simple, rapid and cheap, and an effective way to prepare nano-size perovskite powders. © 2014 Taylor and Francis Group, LLC.
Some of the metrics are blocked by your
consent settings
Rapid synthesis of potassium sodium niobate (K 1/2Na 1/ 2NbO3) lead-free piezoelectric powder using the combustion method
(2013-12-01)
Chaiyo, Nopsiri
;
Muanghlua, Rangson
;
Wongprasert, Yothin
;
Seeharaj, Panpailin
;
Vittayakorn, Naratip
Potassium sodium niobate (K1/<inf>2</inf>Na1/<inf>2</inf>NbO<inf>3</inf>) powder was synthesized successfully by the combustion synthesis. The raw materials of KNO<inf>3</inf>, NaNO<inf>3</inf> and Nb<inf>2</inf>O<inf>5</inf> were used with glycine as fuel. The thermal behaviour of the precursor was determined using thermo gravimetric analysis (TGA) and derivative thermo gravimetric (DTG) analysis. The conditions for preparing perovskite phase formation, influence of the fuel-to-oxidizer molar ratio, and crystal structure were characterized by the X-ray diffraction technique (XRD) and Fourier transform infrared (FTIR) spectroscopy. The morphology and particle size were investigated through a scanning electron microscope (SEM). © 2013 Copyright Taylor and Francis Group, LLC.
Some of the metrics are blocked by your
consent settings
Microwave-assisted solution combustion synthesis and characterization of thermoelectric Ca3Co2O6 powders
(2013-10-29)
Kahatta, Sagulthai
;
Chaiyo, Nopsiri
;
Ruttanapun, Chesta
;
Techitdheera, Wicharn
;
Pecharapa, Wisanu
The microwave-assisted solution combustion synthesis was applied to the initial synthesizing of Ca<inf>3</inf>Co<inf>2</inf>O<inf>6</inf> powder using glycine as a fuel and nitrate as an oxidant. The assynthesized powders were calcined at 700-1,000°C for 4h. Product characterization was performed using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Scanning electron microscope (SEM). The fuel-to-oxidizer molar ratio was found to affect the combustion reaction and character of the powder obtained. The phase composition of powder after calcination at various temperatures has shown that the formation of Ca<inf>3</inf>Co<inf>2</inf>O<inf>6</inf> occurs directly. The calcined powder possesses a rhombohedral crystal structure with an X-ray diffraction pattern that could be matched with the Ca<inf>3</inf>Co<inf>2</inf>O<inf>6</inf>JCPDS: 89-0629. This method is a simple way of synthesizing fine Ca<inf>3</inf>Co<inf>2</inf>O<inf>6</inf> powder with a low calcination temperature. © (2013) Trans Tech Publications, Switzerland.
Some of the metrics are blocked by your
consent settings
Combustion synthesis of lead-free piezoelectric alkali metal niobate family
(2013-01-01)
Chaiyo, Nopsiri
;
Muanghlua, Rangson
;
Wongprasert, Yothin
;
Seeharaj, Panpailin
;
Vittayakorn, Naratip
Nano-crystalline alkali metal niobate (ANbO<inf>3</inf>; A = K and Na) powders were synthesized by the combustion of nitrate compounds and Nb <inf>2</inf>O<inf>5</inf> using glycine as the fuel. The chemical reaction, nucleation mechanisms and influence of the fuel-to-oxidizer ratio to phase formation were studied. The precursor and product powders were characterized, using the thermo gravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) technique, and scanning electron microscopy (SEM). Different fuel-to-oxidizer ratios were found to be a key factor of the process. As-prepared and calcined powders provided the perovskite structure with a nano-scale of mean crystalline size. © 2013 Copyright Taylor and Francis Group, LLC.
Some of the metrics are blocked by your
consent settings
Non-isothermal kinetics of the thermal decomposition of sodium oxalate Na2C2O4
(2012-03-01)
Chaiyo, Nopsiri
;
Muanghlua, Rangson
;
Niemcharoen, Surasak
;
Boonchom, Banjong
;
Seeharaj, Panpailin
The thermal transformation of Na<inf>2</inf>C<inf>2</inf>O<inf>4</inf> was studied in N<inf>2</inf> atmosphere using thermo gravimetric (TG) analysis and differential thermal analysis (DTA). Na<inf>2</inf>C<inf>2</inf>O<inf>4</inf> and its decomposed product were characterized using a scanning electron microscope (SEM) and the X-ray diffraction technique (XRD). The non-isothermal kinetic of the decomposition was studied by the mean of Ozawa and Kissinger-Akahira-Sunose (KAS) methods. The activation energies (Eα) of Na<inf>2</inf>C<inf>2</inf>O<inf>4</inf> decomposition were found to be consistent. Decreasing Eα at increased decomposition temperature indicated the multi-step nature of the process. The possible conversion function estimated through the Liqing-Donghua method was 'cylindrical symmetry (R <inf>2</inf> or F<inf>1/2</inf>)' of the phase boundary mechanism. Thermodynamic functions (DH*, DG* and DS*), calculated by the Activated complex theory and kinetic parameters, indicated that the decomposition step is a high energy pathway and revealed a very hard mechanism. © Akadémiai Kiadó, Budapest, Hungary 2011.
Some of the metrics are blocked by your
consent settings
Facile synthesis of lead-free piezoelectric sodium niobate (NaNbO 3) Powders via the solution combustion method
(2011-07-29)
Chaiyo, Nopsiri
;
Ruangphanit, Anucha
;
Boonchom, Banjong
;
Vittayakorn, Naratip
Nanocrystalline perovskite sodium niobate, NaNbO<inf>3</inf> (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 NaNbO <inf>3</inf> 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. Copyright © Taylor &Francis Group, LLC.
Some of the metrics are blocked by your
consent settings
Synthesis of potassium niobate (KNbO3) nano-powder by a modified solid-state reaction
(2011-03-01)
Chaiyo, Nopsiri
;
Ruangphanit, Anucha
;
Muanghlua, Rangson
;
Niemcharoen, Surasak
;
Boonchom, Banjong
Crystalline lead-free piezoelectric potassium niobate (KNbO<inf>3</inf>) powders have been synthesized through a modified solid-state reaction method. The thermal behavior of the K<inf>2</inf>C<inf>2</inf>O<inf>4</inf>-H <inf>2</inf>O and Nb<inf>2</inf>O<inf>5</inf> raw material mixture was investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The X-ray diffraction technique (XRD) was used to investigate the phase formation and purity. The morphology of the powder obtained was characterized using a scanning electron microscope (SEM). The XRD pattern showed that the monophasic perovskite phase of KNbO<inf>3</inf> could be synthesized successfully at a temperature as low as 550 °C for 240 min, with an average crystallite size of 36 ± 8 nm. The SEM images suggested that the average particle size of the powder obtained was 278 ± 75 nm. © Springer Science+Business Media, LLC 2010.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results