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Chiang Mai, Thailand

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. Source


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. Source


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. Source


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. Source


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. Source

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