Chiang Mai, Thailand
Chiang Mai, Thailand

Time filter

Source Type

Pisitpipathisin N.,Chiang Mai University | Kantha P.,Chiang Mai University | Inthata U.,Chiang Mai University | Eitssayeam S.,Chiang Mai University | And 6 more authors.
Ferroelectrics | Year: 2011

Glasses have been formed from PbO-Bi 3O 2-GeO 2 system by conventional meltquenching method. The glasses were melted in Pt crucible in an air atmosphere. The resulting glass pieces were subjected to the heat treatment schedule at various crystallization temperatures. The glass and glass-ceramics samples were then investigated by XRD and SEM spectroscopy. The dielectric and ferroelectric properties were also measured. Moreover, DTA analysis has been used to examine the crystallization temperatures of glasses. The controlled heat treatment process has been applied to the crystallization temperatures and glass-ceramic samples were obtained. The XRD showed that the crystals of ferroelectric phase, hexagonal Pb 3Bi 2(GeO 4) 3;PBG, were precipitated in the glass matrix and this is the dominant phase in the region of 34.50 mol% PbO: 11.49 mol% Bi 2O 3: 54.01 mol% GeO 2 on the heat treatment temperature at 527°C. The dielectric constant (er) and P-E loop of Pb 3Bi 2(GeO 4) 3 glass-ceramic confirmed that this material may have high possibility to be ferroelectric at room temperature with coercive field (Ec) of 30.9 kV/cm. However, the remanent polarization (Pr) = 1.36 μC/cm 2 is rather small, therefore it is quite difficult to confirm that the P-E loop is the feature of truly ferroelectric, it may represent a lossy capacitor behavior. Copyright © Taylor & Francis Group, LLC.


Yongsiri P.,Chiang Mai University | Eitssayeam S.,Chiang Mai University | Eitssayeam S.,Materials Science Research Center | Sirisoonthorn S.,National Metal and Materials Technology Center | And 2 more authors.
Electronic Materials Letters | Year: 2013

In this research, the fabrication of lead-free ferroelectric glass-ceramics from the (K0.5Na0.5)NbO3 system via incorporation method was carried out. For the incorporation method, calcined KNN was added into glass batches as a heterogeneous nucleating agent. Glass-ceramics KNNs were prepared from two compositions of KNN-SiO2 with a ratio of 75: 25 (C1) and 80: 20 (C2) mol.%. Thermal properties resulting from DTA showed samples C1 and C2 having glass transition temperatures of 532°C and 520°C and crystallization temperatures of 645°C and 620°C, respectively. The prepared glasses were subsequently subjected to a heat treatment schedule in a temperature range of 500°C - 575°C for crystallization. XRD results showed that the KNN phase occurred in C1. The C2 glass-ceramic samples contained unidentified phases together with the KNN phase. From SEM observation, it was found that bulk crystals with an equiaxed shape of KNN phase dispersed well in all glass-ceramic matrices. Crystal sizes increased with increasing heat treatment temperatures. In C2 glass-ceramics, unidentified phases were found together with the KNN phase. © 2013 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.


Kantha P.,Chiang Mai University | Pisitpipathsin N.,Chiang Mai University | Leenakul W.,Chiang Mai University | Eitssayeam S.,Chiang Mai University | And 6 more authors.
Ferroelectrics | Year: 2011

To study the effect of thermal annealing on the electrical properties of lead-free Bi 2GeO 5 ferroelectric glass ceramics, the glass ceramics with composition of Bi 2GeO 5 were prepared by the conventional melt-quenching and heat-treatment methods subsequently. Glass ceramics of Bi2GeO5 was produced by subjecting the glasses from BiO 1.5-GeO 2-BO 1.5 system to the heat treatment schedule at 475°C for 18 h. After that, the resulting samples were separately annealed at 275 and 375°C for 4, 8, 12 and 18 h, respectively. The important properties of the annealed Bi 2GeO 5 glass ceramics such as physical properties, phase formation and electrical properties were then investigated. It was found that the annealing treatment played an important role on electrical properties of these glass ceramics. The XRD patterns confirm the secondary phase of Bi 4Ge 3O 12 co-existed with Bi 2GeO 5 which increased at higher annealing temperature and time. This caused a change in density and related electrical properties of the Bi 2GeO 5 glass ceramics. Both annealing temperature of 275 and 375°C with various times can improve dielectric properties and ferroelectric behavior of the resulting Bi 2GeO 5 glass ceramics when comparing with that of un-annealed sample. The optimum annealing temperature and time for the improvement of dielectric properties of Bi 2GeO 5 glass ceramics was found at 375°C/12 h, where the maximum values of the dielectric constant (er) of 246 and low dielectric loss (tand) of 0.024 were obtained. Moreover, the ferroelectric property of all annealed glass ceramics exhibited the slim P-E loop and Pr values which slightly increased with increasing annealing temperature and time. However, the P-E loops are not the feature of truly ferroelectric, it may be represent a lossy capacitor behavior. Copyright © Taylor & Francis Group, LLC.


Yongsiri P.,Chiang Mai University | Eitssayeam S.,Chiang Mai University | Eitssayeam S.,Materials Science Research Center | Inthata U.,Mae Fah Luang University | And 7 more authors.
Ferroelectrics | Year: 2011

In this research, the fabrication of glass ceramics containing ferroelectric KNN crystals has been carried out in aluminosilicate glass system by using conventional mixed oxide technique in alumina crucible. Alumina was chosen to increase mechanical robust and the stability of KNN glass ceramic in ratio 0, 5, 10 and 15 mol%. The received glass ceramics were all transparent. The glasses were subjected to heat treatment processes at the temperature between 600 and 700°C in order to form the glass ceramics with desired crystal phases. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used for phase identification and microstructural studies, respectively. The bulk crystallization of KAlSiO2 phase was observed in the glass ceramics with heat treatment temperatures from 600 - 675°C while KNN phase started to appear at higher temperature of 700°C. The glass ceramic containing 23.75 mol% SiO2 possesses the optimum values of dielectric constant (er): ∼260 and low dielectric loss (tand): ∼0.02 at 10 kHz in room temperature. Copyright © Taylor & Francis Group, LLC.


Saiwanich P.,Chiang Mai University | Pengpat K.,Chiang Mai University | Pengpat K.,Materials Science Research Center | Rujijanagul G.,Chiang Mai University | And 4 more authors.
Advanced Materials Research | Year: 2012

In this work, thepreparation and morphology of biphasic calcium phosphate (BCP) have been studied. The biphasic calcium phosphate(BCP) ceramics were prepared by mixing between hydroxyapatite (HA) and Beta-tricalcium phosphate (β-TCP) powder by ball milling technique with different ratios (100:0, 80:20, 60:40, 50:50, 40:60, 20:80 and 0:100). After that the mixtures were forming by Gel casting method and then sintered at 1200°C, respectively. The phase formation of the biphasic calcium phosphateceramics were studied by X-ray diffraction (XRD) and their ceramic microstructure, shrinkage and density were investigated. © (2012) Trans Tech Publications.


Yongsiri P.,Chiang Mai University | Mhuangthong P.,Chiang Mai University | Munpakdee A.,Srinakharinwirot University | Pengpat K.,Chiang Mai University | Pengpat K.,Materials Science Research Center
Ferroelectrics | Year: 2014

In the present study, potassium sodium niobate (KNN) doped with Er 2O3 in TeO2 glasses were successfully prepared using melting-quenching method. The glass composition of 70KNN-30TeO2 mol% doped with 1 mol% of Er2O3 has been chosen. A batch was subsequently melted at 800°C and 900°C for 30-60 min and heated at the temperature ranging between 300-530°C in order to form the glass ceramics with desired crystal phases. XRD results showed that KNN crystals distributed over the glass-ceramic samples. From SEM observation, it was found that nano-crystals of several phases were precipitated in all glass-ceramic matrices. Dielectric constant increased with increasing heat treatment temperature. © 2014 Taylor and Francis Group, LLC.


Phothawan A.,Chiang Mai University | Nganvongpanit K.,Chiang Mai University | Tunkasiri T.,Chiang Mai University | Tunkasiri T.,Materials Science Research Center | And 2 more authors.
Advanced Materials Research | Year: 2012

The aim of this research is to study the mechanical properties such as hardness, wear resistance etc, of the magnesium oxide (MgO) doped alumina (Al 2O 3) and yttria stabilized zirconia (YSZ) composite, We first prepared MgO-doped Al 2O 3 (denoted as Al 4) by mixing Al 2O 3 powder and 0.4 wt% of MgO powder. After that Al 4 powder was mixed YSZ powder, with the formula [(x)Al 4 - (100-x)YSZ] when x was varied from 0 - 100 by wt%. The samples were sintered at 1450, 1500, 1550, 1600 and 1650 °C. In addition, microstructure of the surface was studied employing both optical and scanning electron microscopes. The hardness of the surface was investigated by Vickers indentation technique and pin on disk apparatus was employed for wear rate measurement. The results showed that the density and volume shrinkage decreased with the increase of Al 4 content. The grain size and porosity of the specimens tend to decrease when the sintering temperature increases. The hardness and wear resistance of the samples increased with the increase of Al 4 up to 90 %. It was also found that the material is not toxic to the body. © (2012) Trans Tech Publications.


Panyata S.,Chiang Mai University | Eitssayeam S.,Chiang Mai University | Eitssayeam S.,Materials Science Research Center | Rujijanagul G.,Chiang Mai University | And 5 more authors.
Advanced Materials Research | Year: 2012

In this research, the two-step sintering method was employed to develop the physical properties of Hydroxyapatite (HA) ceramics. HA powder was extracted from bovine bone and vibro-milling method was used to make the fine particles. For the two-step sintering process, the samples were heated up to the first step temperature (T 1=1200°C) for 6 min then the temperature was lowered down to second step temperatures (T 2=1150°C and 1100°C) for 5, 10 and 15 h. Another set of samples were heated up to the first step temperature (T 1=1250°C) for 6 min then the temperature was lowered down to second step temperature (T 2=1150°C) for 5, 10 and 15 h. X-ray diffraction (XRD) was carried out for investigating the phase formation in the prepared ceramics. Physical properties of the prepared ceramics were studied such as porosity, density by Archimedes's principle. It is found that most of the samples exhibit Ca 5(PO 4) 3(OH) phase with JCPDS number 09-0432. The first step temperature plays the most roles on controlling the density of HA ceramics than T 2 and dwell times. Microstructures of the HA powder and ceramics were characterized using scanning electron microscope (SEM). The feasibility in using the prepared ceramics for bone replacement applications was discussed. © (2012) Trans Tech Publications.


Naeem S.,Materials Science Research Center | Zafar U.,Materials Science Research Center | Zahra N.,Materials Science Research Center | Rasool G.,Materials Science Research Center
Journal of the Chemical Society of Pakistan | Year: 2010

In this investigation, adsorption of Cu2+ on α-Alumina has been studied by means of batch-technique. Percentage adsorption was determined for α-Alumina-Copper solution system as a function of contact time, pH, adsorbate concentration and temperature. Adsorption data has been interpreted in terms of Freundlich and Langmuir equations. Thermodynamics parameters for the adsorption system have been determined at three different temperatures. The value of ΔHo= 15.822KJ/mole and ΔGo=-1.0775KJ/ mole at 288K suggest that the adsorption of copper on α-Alumina is endothermic and spontaneous process. The desorption studies especially with 1 % NaOH, 1% CaCl2and 1%HC1 at given copper loadings on α-Alumina show that no significant percentage of the element is reversibly desorbed.


Yongsiri P.,Chiang Mai University | Pengpat K.,Chiang Mai University | Pengpat K.,Materials Science Research Center
Integrated Ferroelectrics | Year: 2013

In this research, materials characterization of transparent glass-ceramics containing ferroelectric potassium sodium niobate (K0.5Na 0.5)NbO3 (KNN) crystals in a tellurite glass system were studied. The samples were prepared via an incorporation method. Glass-ceramics containing KNN crystals were successfully fabricated by mixing KNN calcined powder with TeO2 of about 70 and 80 mol% and melting at 800°C for 15 min in a platinum crucible. The prepared glasses were then subjected to heat treatment at 350-550°C. The optical properties of the samples were characterized by UV-Vis-NIR and ellipsometer. It was found that heat treatment temperature had significantly affected the optical properties. XRD patterns of the glass-ceramics revealed an amorphous-like structure with different degrees of crystallinity. SEM results confirmed the XRD data, where the degree of crystallinity increased with increasing heat treatment temperature. Copyright © Taylor & Francis Group, LLC.

Loading Materials Science Research Center collaborators
Loading Materials Science Research Center collaborators