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Dielectric and Ferroelectric Properties of Nb Doped BNT-Based Relaxor Ferroelectrics
Maqbool, Adnan,Hussain, Ali,Malik, Rizwan Ahmed,Zaman, Arif,Song, Tae Kwon,Kim, Won-Jeong,Kim, Myong-Ho Materials Research Society of Korea 2015 한국재료학회지 Vol.25 No.7
The effects of Nb doping on the crystal structure, microstructure, and dielectric ferroelectric and piezoelectric properties of $(Bi_{0.5}Na_{0.5})_{0.935}Ba_{0.065}Ti_{(1-x)}Nb_xO_3-0.01SrZrO_3$ (BNBTNb-SZ, with ${\chi}=0$, 0.01 and 0.02) ceramics have been investigated. X-ray diffraction patterns revealed that all ceramics have a pure perovskite structure with tetragonal symmetry. The grain size of the ceramics slightly decreased and a change in grain morphology from square to spherical shape was observed in the Nb-doped samples. The maximum dielectric constant temperature ($T_m$) increases with increasing amount of Nb; however, ferroelectric-relaxor transition temperature ($T_{F-R}$) and maximum dielectric constant (${\varepsilon}_m$) values decrease gradually. Nb addition disrupted the polarization hysteresis loops of the BNBT-SZ ceramics by leading a reduction in the remnant polarization coercive field and piezoelectric constant.
Adnan Maqbool,Ali Hussain,Jamil Ur Rahman,Rizwan Ahmed Malik,송태권,Myong Ho Kim,Won Jeong Kim 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.12
The influence of SrZrO3 (SZ) addition on the crystal structure, piezoelectric and the dielectric properties of lead-free Bi0.5Na0.5TiO3 (BNT−SZ100x, with x = 0 − 0.10) ceramics was systematically investigated. A significant reduction in the grain size was observed with SZ substitution. The X-ray diffraction analysis of the sintered BNT−SZ ceramics revealed a single perovskite phase with a pseudocubic symmetry; however, electric poling indicated a non-cubic distortion in the poled BNT−SZ ceramics. With increase in the SZ content, the temperature of maximum dielectric constant (Tm) shifted towards lower temperatures, and the curves became more diffuse. Enhanced piezoelectric constant (d33 = 102 pC/N) and polarization response were observed for the BNT−SZ5 ceramics. The results indicated that SZ substitution induced a transition from a ferroelectric to relaxor state with a field-induced strain of 0.24% for BNT−SZ9 corresponding to a normalized strain of 340 pm/V.
Ali HUSSIN,Adnan Maqbool,Rizwan Ahmed Malik,김민수,송태권,김명호,Arif Zaman,김원정 한국물리학회 2015 새물리 Vol.65 No.8
Bi0.5Na0.5TiO3 (BNT) templates with a single phase perovskite structure were produced from a plate-like precursor particles of bismuth-layer-structured ferroelectric Bi4.5Na0.5Ti4O15 (BNT4) through a topochemical microcrystal conversion process. First, the plate-like BNT4 precursor particles were prepared via molten salt synthesis. The layered structure BNT4 transformed into a single phase perovskite BNT templates after its topochemical reaction with the complementary Na2CO3 and TiO2 reactants at 950 ℃ for 4 h in a NaCl flux. The as synthesized BNT templates exhibited large grains (range from 10 to 15 μm), had plate-like morphology and exhibits a single-phase perovskite structure with a pseudo-cubic symmetry. Furthermore, the temperature dependences of dielectric constant and loss at different frequencies showed a relaxor behavior, and polarization versus electric field curves exhibited a typical ferroelectric response.
Hussain, Ali,Maqbool, Adnan,Malik, Rizwan Ahmed,Lee, Jae Hong,Kim, Myong Ho,Song, Tae Kwon,Kim, Won Jeong American Scientific Publishers 2018 Science Of Advanced Materials Vol.10 No.2
<P>This article describes structural characterization of the Na0.5Bi0.5TiO3 (NBT) particles produced using the following techniques: topochemical microcrystal conversion (TMC), molten salt synthesis (MSS) and conventional mixed-oxide (CMO). The NBT particles produced by the TMC method showed high-aspect-ratio plate-like grains. However, the NBT particles prepared by the MSS and CMO methods show equiaxial grains of sizes less than approximately one micron. All NBT particles produced by the three techniques had a similar crystal structure, but different grain orientations. The crystal structure results of these particles were confirmed by transmission electron microscope (TEM) analysis, which showed (100) grain growth for NBT produced by the TMC and along (110) for the same NBT compositions produced by the MSS and CMO methods.</P>
Hussain, Ali,Maqbool, Adnan,Malik, Rizwan Ahmed,Zaman, Arif,Lee, Jae Hong,Song, Tae Kwon,Lee, Jae Hyun,Kim, Won Jeong,Kim, Myong Ho Materials Research Society of Korea 2015 한국재료학회지 Vol.25 No.10
$Bi_{0.5}Na_{0.5}TiO_3$ (BNT) based ceramics are considered potential lead-free alternatives for $Pb(Zr,Ti)O_3$(PZT) based ceramics in various applications such as sensors, actuators and transducers. However, BNT-based ceramics have lower electromechanical performance as compared with PZT based ceramics. Therefore, in this work, lead-free bulk $0.99[(Bi_{0.5}Na_{0.5})_{0.935}Ba_{0.065}]_{(1-x)}La_xTiO_3-0.01SrZO_3$ (BNBTLax-SZ, with x = 0, 0.01, 0.02) ceramics were synthesized by a conventional solid state reaction The crystal structure, dielectric response, degree of diffuseness and electric-field-induced strain properties were investigated as a function of different La concentrations. All samples were crystallized into a single phase perovskite structure. The temperature dependent dielectric response of La-modified BNBT-SZ ceramics showed lower dielectric response and improved field-induced strain response. The field induced strain increased from 0.17%_for pure BNBT-SZ to 0.38 % for 1 mol.% La-modified BNBT-SZ ceramics at an applied electric field of 6 kV/mm. These results show that La-modified BNBT-SZ ceramic system is expected to be a new candidate material for lead-free electronic devices.
Muhammad Asif Hussain,최은주,Adnan Maqbool,Muhammad Atif,Hassan Zeb,여재구,유정아,조영훈,Moses Noh,김정원 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.99 No.-
A facile eco-friendly heterogeneous catalytic system has been developed for amide synthesis that furtherutilized in pharmaceutical and organic chemistry. The Ru/MnO2 catalyst has shown outstanding andunprecedented activity for a wide range of aliphatic and benzylic nitriles in green solvent water at 60 C. The system has also exhibited a remarkable tolerance for selective hydration of heteroatom (e.g. nitrogen,oxygen and sulphur atoms) containing nitriles. Pharmaceutically important nicotinamides andpyrazinamide has been synthesized by hydration of the heteroatomic nitriles with appreciable yieldsand selectivities. Moreover, the Ru/MnO2 catalyst has employed water as a benign solvent, with morethan 30,000 TONs and reusabilityfive times after isolation from the reaction mixture by centrifugationand easy workup that established a path for green environmental and technologically acceptableprotocol.
Zaman, Arif,Malik, Rizwan Ahmed,Maqbool, Adnan,Hussain, Ali,Ahmed, Tanveer,Song, Tae Kwon,Kim, Won-Jeong,Kim, Myong-Ho Minerals, Metals & Materials Society and the Insti 2018 Journal of electronic materials Vol.47 No.3
<P>Crystal structure, dielectric, ferroelectric, piezoelectric, and electric field-induced strain properties of lead-free Nb-modified 0.96Bi(0.5)K(0.5)TiO(3)-0.04Bi(Mg0.5Ti0.5)O-3 (BKT-BMT) piezoelectric ceramics were investigated. Crystal structure analysis showed a gradual phase transition from tetragonal to pseudocubic phase with increasing Nb content. The optimal piezoelectric property of small-signal d (33) was enhanced up to similar to 68 pC/N with a lower coercive field (E (c)) of similar to 22 kV/cm and an improved remnant polarization (P (r)) of similar to 13 mu C/cm(2) for x = 0.020. A relaxor-like behavior with a frequency-dependent Curie temperature T (m) was observed, and a high T (m) around 320A degrees C was obtained in the investigated system. This study suggests that the ferroelectric properties of BKT-BMT was significantly improved by means of Nb substitution. The possible shift of depolarization temperature T (d) toward high temperature T (m) may have triggered the spontaneous relaxor to ferroelectric phase transition with long-range ferroelectric order without any traces of a nonergodic relaxor state in contradiction with Bi0.5Na0.5TiO3-based systems. The possible enhancement in ferroelectric and piezoelectric properties near the critical composition x = 0.020 may be attributed to the increased anharmonicity of lattice vibrations which may facilitate the observed phase transition from a low-symmetry tetragonal to a high-symmetry cubic phase with a decrease in the lattice anisotropy of an undoped sample. This highly flexible (at a unit cell level) narrow compositional range triggers the enhancement of d (33) and P (r) values.</P>