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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.
Amir Ullah,Muneeb-ur-Rahman,Muhammad Javid Iqbal,Chang Won Ahn,Ill Won Kim,Aman Ullah 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.12
The electrical properties of the 0.925(Bi0.5(Na0.40K0.10)TiO3-0.075(Ba0.70Sr0.30)TiO3 (0.925BNKT-0.075BST) ceramic were investigated by using AC impedance spectroscopy over a wide range of frequencies (10−2 105 Hz). The X-ray diffraction patterns confirmed the formation of a single-phase compound. A single semicircular arc in the impedance spectrum indicates that the main contribution of the bulk resistance (Rb) were due to grain effects, with Rb decreasing with increasing temperature. The conductivity of the ceramics increased with increasing temperature, and the activation energy resulting from the DC conductivity was 0.86 eV. The ceramic displayed a typical negative temperature coefficient of resistance (NTCR) behavior, like that of a semiconductor.
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.
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.
Ju Sung Kim,Chang Won Ahn,Amir Ullah,Song A. Chae,Ill Won Kim 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.12
The Li, Ta, and Sb-substituted lead-free (K0.44Na0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3 (KNLNTS) thin films were fabricated on Pt(111)/TiO2/SiO2/Si substrates using the radio frequency (RF) magnetron sputtering method. The KNLNTS thin films were annealed at 750 C for 1 h in an oxygen ambient. The film with a thickness of 350 nm exhibited a typical ferroelectric P − E hysteresis loop without fatigue even after 1010 pulses. The KNLNTS thin film exhibited a relatively low leakage current density of 10−7 A/cm2 even up to an applied electric field of 142 kV/cm. A well-saturated piezoelectric hysteresis loop was obtained with a piezoelectric coefficient d33 of 21 pm/V.
Static Magnetic Properties of Maghemite Nanoparticles
Zulfiqar,Muneeb Ur Rahman,M. Usman,Syed Khurshid Hasanain,Zia-ur-Rahman,Amir Ullah,Ill Won Kim 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.11
We report the static magnetic properties of Maghemite (-Fe2O3) nanoparticles with an averagecrystallite size of 14 ± 1.8 nm synthesized via a co-precipitation method. The zero-field-cooled(ZFC) and the field-cooled (FC) magnetization measurements were performed using a physicalproperties measurements system (PPMS) at temperatures from 5 K to 300 K. The ZFC/FC measurementsshowed a typical superparamagnetic behavior with a narrow size distribution.
Muhammad Khalid Alamgir,M. Ikram,Ghalib Hussain Mughal,Ghulam Asghar,Sha q ur Rehman,S. Qaseem,M. Kamran,Amir Ullah,Sartaj Khan 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.5
Non-evaporable getter (NEG) thin films of Ti-Al-Zr and Ti-Zr were prepared on stainless-steel substrate by using the cathodic arc deposition technique. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and in-situ X-ray photoelectron spectroscopy (XPS) were used to analyze the getter behavior of the non-evaporable getter thin films. The SEM images displayed the porous and rough surfaces of the thin films, which is an indication of high adsorption and sticking probabilities for the residual gases present in the chamber. The volume elemental composition of the thin films was measured by using EDX. The XRD patterns of the synthesized thin films indicated that the films had an amorphous nature and high structural stability. The in-situ X-ray photoelectron spectroscopy (XPS) studies revealed that the superficial layers disappeared when the non-evaporable getter of Ti-Al-Zr thin films was heated at a temperature below 250~$^\circ$C for 30 minutes, there by activating the surface. However, for Ti-Zr thin films, no reasonable activation was observed at 250~$^\circ$C. This outcome reveals that thin films of Ti-Al-Zr are good for reducing the outgassing and producing an ultra-high vacuum.