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Influence of Particle Size and Sintering Temperatures on Electrical Properties of 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 Lead Free Ceramics

Gul Mert, Gurbuz Mevlüt, Gokceyrek Abdi B., Toktaş Aysegül, Kavas Taner, Dogan Aydın

Archives of Metallurgy and Materials

2020

Vol. 65, iss. 2

609--614

In this study, lead-free 0.94 Na0.5 Bi0.5 TiO3 -0.06BaTiO3 (NBT-BT) compositions at morphotropic phase boundary were successfully synthesized by solid-state reaction method. The effects of the particle size for various milling time (12-24-48 hours) and sintering temperatures (1100-1125-1150-1175°C for 2 h) on the electrical properties of the NBT-BT ceramics were evaluated. Experimental results showed that particle size and sintering temperatures significantly affect the electrical properties of NBT-BT ceramics. The particle size of the ceramic powders decreasing while milling time increases to 48 hours. Particle size values for 0, 12, 24 and 48 hours (h) milled powders were measured as nearly 1.5 μm, 1 μm, 700 nm, and 500 nm respectively. The bulk density enhanced with increasing sintering temperature and showed the highest value (5.73 g/cm3) at 1150°C for 48 h milled powder. Similarly, the maximum piezoelectric constant (d33 ) = 105 pC/N, electromechanical coupling coefficient (kp ) = 25.5% and dielectric constant (KT) = 575 were measured at 1150°C for 48 h milled powder. However, mechanical quality factor (Qm ) was reduced from 350 to 175 with decreasing particle size. Similarly, remnant polarization was dropped by decreasing powder particle size from 56 μC/cm2 to 45 μC/cm2.

Dielectric and Raman studies of Ba0.06(Na1/2Bi1/2)0.94TiO3–NaNbO3 ceramics

Roy S. K., Chaudhuri S., Kotnala R. K., Singh D. K., Singh B. P., Singh S. N., Chandra K. P., Prasad K.

Materials Science Poland

2016

Vol. 34, No. 2

437--445

In this work the X-ray diffraction, scanning electron microscopy, Raman and dielectric studies of lead free perovskite (1 – x)Ba0.06(Na1/2Bi1/2)0.94TiO3–xNaNbO3 (0 ≤x ≤ 1.0) ceramics, prepared using a standard solid state reaction method, were investigated. X-ray diffraction studies of all the ceramics suggested the formation of single phase with crystal structure transforming from rhombohedral-tetragonal to orthorhombic symmetry with the increase in NaNbO3 content. Raman spectra also confirmed the formation of solid solution without any new phase. Dielectric studies showed that the phase transition is of diffusive character and diffusivity parameter decreases with increasing NaNbO3 content. The compositional fluctuation was considered to be the main cause of diffusivity.

The Effect Of Void Formation On The Reliability Of ED-XRF Measurements In Lead-Free Reflow Soldering

Koncz-Horváth D., Gergely G., Gacsi Z.

Archives of Metallurgy and Materials

2015

Vol. 60, iss. 2B

1445--1448

In lead-free reflow soldering, the presence of voids should be taken into account. For this reason, the effect of the applied heating profiles was examined via the characterization of voids in galvanic and immersion Sn coatings. According to EU Directive 2002/95/EC, the screening of Pb element of reflow soldering (i.e. of electrical and electronic equipment) is necessary; and the practical implementation of this measurement is largely affected by the characteristics of the solder (i.e. the presence of voids and the inhomogeneity of the solder). Comparing the results of the above two coating methods, it was found that by chemical coating more voids were formed and the detected lead content was higher than for galvanic Sn. The standard deviation of Ag and Cu concentrations was mainly influenced by the appearance of large compounds in the second case, while with chemical coating, no large compounds were formed due to the elevated number of voids.