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Mateen Ullah,Amir Ullah,Hidayat Ullah Khan,Imtiaz Ahmad,김일원 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.2
Piezoelectric ceramics (Bi0.5Na0.5)0.935Ba0.065Ti1-x(Al0.5Nb0.5)xO3 (BNBT-AN) have been synthesized for x = 0, 0.010, 0.015, 0.020, 0.025, and 0.030 through simple solid state reaction technique. Synthesis and sintering of all the systems were successful as single phase was obtained through out. This work explains the influence of AN on morphology, phase structure, electrical and electromechanical characteristics of the parent BNBT matrix. All compositions were single phase perovskites by X-ray diffraction (XRD), that could be confirmed as the tetragonal, P4/m, and rhombohedral, R3c, mixed structures. Tetragonality was increased with increase in the AN content. With similar modification, dynamic piezoelectric constant d*33 (= Smax/Emax) was increased monotonically gaining a highest value of 354 pm/V corresponding to x = 0.030. The overall increase was found in remnant polarization (Pr) for all the systems except for the one with x = 0.030. Maximum Pr, 30.6 μC/cm^2, was noted for x = 0.025. This phenomenon was also accompanied by a persistent decrease in coercive field Ec, from 28.0 kV/cm for undoped to 14.5 kV/cm for 3 mol%. The ceramics were signified with encouraging electrical properties.
Dielectric and Electromechanical Properties of Zr-Doped BNT-ST Lead-Free Piezoelectric Ceramics
Amir Ullah,Mateen Ullah,Aman Ullah,A. V. Trukhanov,Ghulam Saddiq,Burhan Ullah,Aurang Zeb,Saeed Ullah Jan,김일원 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.74 No.6
0.72(Bi$_{0.5}$Na$_{0.5}$)Ti$_{(1-x)}$Zr$_x$O$_3$-0.28SrTiO$_3$ (BNTZ-ST) with $x$ = 0.00, 0.01, 0.02 and 0.03 were produced using a solid solution reaction procedure. Results from the X-ray diffraction (XRD) analysis showed the presence of a perovskite structure with cubic symmetry for all samples. Surface analysis was completed using field emission scanning electron microscopy (FE-SEM), and the grain size was found to decrease slightly with increasing Zr doping. The grain morphology was primarily rectangular, but morphed into a rounder shape with increases in Zr. In a dielectric constant study, the depolarization temperature was found to decrease with increasing Zr$^{+4}$ content and increasing frequency. The strain was found to be 0.34\% for the undoped samples with an equivalent dynamic strain ($S_{max}/E_{max}$) of 618 pm/V, without negative strain. However, the strain decreased slightly and hysteresis loops become slim and more symmetric, attaining a relaxor ferroelectric behavior with increasing Zr content.
Incipient ferroelectricity of AgTaO3 and ferroelectric nature of (Li0.008Ag0.992)TaO3
Khan Hidayat Ullah,Ullah Amir,Sualiheen Karishma,Ahmad Imtiaz,Ullah Mateen 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.9
AgTaO3 (AT) and ( Li0.008Ag0.992)TaO3 (LAT-0.8) compositions have been fabricated successfully via solid-state reaction (SSR) route. Phase purity of both the calcined powder and crushed sintered pellet was confirmed with XRD peaks which were indexed according to the rhombohedral structure with R3c∕R3c. The smooth hysteretic behavior of the LAT-0.8 system evidenced unlocking of the hidden ferroelectricity of AT. This phenomenon confirmed the incipient ferroelectric/quantum paraelectric nature of AT. So far, the triggering of ferroelectricity with 0.8% Li modification in AT has not been reported in the literature. A fair ferroelectric response of AT and LAT-0.8 at − 20 °C was obtained.