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Malik, Rizwan Ahmed,Hussain, Ali,Maqbool, Adnan,Zaman, Arif,Song, Tae Kwon,Kim, Won Jeong,Kim, Myong Ho Materials Research Society of Korea 2015 한국재료학회지 Vol.25 No.6
New lead-free piezoelectric ceramics $0.96[\{Bi_{0.5}(Na_{0.84}K_{0.16})_{0.5}\}_{1-x}La_x(Ti_{1-y}Nb_y)O_3]-0.04SrTiO_3$ (BNKT-ST-LN, where $x=y=0.00{\leq}(x=y){\leq}0.015)$ were synthesized using the conventional solid-state reaction method. Their crystal structure, microstructure, and electrical properties were investigated as a function of the La and Nb (LN) content. The X-ray diffraction patterns revealed the formation of a single-phase perovskite structure for all the LN-modified BNKT-ST ceramics in this study. The temperature dependence of the dielectric curves showed that the maximum dielectric constant temperature ($T_m$) shifted towards lower temperatures and the curves became more diffuse with an increasing LN content. At the optimum composition (LN 0.005), a maximum value of remnant polarization ($33C/cm^2$) with a relatively low coercive field (22 kV/cm) and high piezoelectric constant (215 pC/N) was observed. These results indicate that the LN co-modified BNKT-ST ceramic system is a promising candidate for lead-free piezoelectric materials.
Malik, Rizwan Ahmed,Hussain, Ali,Acosta, Matias,Daniels, John,Han, Hyoung-Su,Kim, Myong-Ho,Lee, Jae-Shin Elsevier 2018 Journal of the European Ceramic Society Vol.38 No.6
<P><B>Abstract</B></P> <P>In this work, the relationship between the structural mechanisms and macroscopic electrical properties of the Nb-modified 0.96(Bi<SUB>0.5</SUB>Na<SUB>0.84</SUB>K<SUB>0.16</SUB>TiO<SUB>3</SUB>)–0.04SrTiO<SUB>3</SUB> (BNKT–ST) system were elucidated by using temperature dependent and <I>in situ</I> synchrotron X-ray diffraction (XRD) techniques. For the composition <I>x</I> = 0.0175, a large-signal piezoelectric coefficient (<I>S</I> <SUB>max</SUB>/<I>E</I> <SUB>max</SUB> = <I>d</I> <SUB>33</SUB>*) of 735 pm V<SUP>−1</SUP> at 6 kV mm<SUP>−1</SUP> was observed at room temperature. Interestingly, at a higher temperature of 110 °C, the sample still showed a large <I>d</I> <SUB>33</SUB>* of 570 pm V<SUP>−1</SUP>. Furthermore, the temperature-invariant electrostrictive coefficient for this sample was found to be 0.0285 m<SUP>4</SUP> C<SUP>−2</SUP> over the temperature range of 25–170 °C. Moreover, the energy density for <I>x</I> = 0.030 sample was ∼1.0 J cm<SUP>−3</SUP> with an energy storage efficiency of ˃70% in the temperature range of 25–135 °C. These results suggest that the synthesized Nb-modified BNKT–ST system is promising for the design of ceramic actuators as well as capacitor applications.</P>
Malik, Rizwan Ahmed,Zaman, Arif,Hussain, Ali,Maqbool, Adnan,Song, Tae Kwon,Kim, Won-Jeong,Sung, Yeon Soo,Kim, Myong-Ho Elsevier 2018 Journal of the European Ceramic Society Vol.38 No.4
<P><B>Abstract</B></P> <P>Lead free piezoelectric ceramics (1–<I>x</I>) (0.67Bi<SUB>1.05</SUB>FeO<SUB>3</SUB>–0.33BaTiO<SUB>3</SUB>)–<I>x</I>LiNbO<SUB>3</SUB> with <I>x</I> =0.00, 0.015 and 0.030 were prepared by using conventional mixed oxide route. The incorporation of LiNbO<SUB>3</SUB> into BF–BT system caused no significant change in crystal structure. However, an obvious variation in electrical properties was observed. The <I>x</I> =0.015 composition showed enhanced ferroelectric and electric field-induced strain properties with dynamic piezoelectric constant <I>S</I> <SUB>max</SUB>/<I>E</I> <SUB>max</SUB> =440 pm/V at a relatively low field of 40kV/cm, along with a high working temperature upto <I>T</I> <SUB>m</SUB> =392°C. LiNbO<SUB>3</SUB> addition improved the temperature insensitivity of relative permittivity (ε<SUB>r</SUB>) at high temperatures. At <I>x</I> =0.030, a near-plateau ε<SUB>r</SUB> ∼5000, extended across the temperature range, 200°C–500°C was observed which is advantageous for temperature insensitive dielectric ceramics for high temperature capacitor applications. Large strain and almost temperature invariant ε<SUB>r</SUB> with high working temperature range makes this system suitable for high temperature electronic devices.</P>
Akram, Fazli,Malik, Rizwan Ahmed,Lee, Soonil,Pasha, Riffat Asim,Kim, Myong Ho Materials Research Society of Korea 2018 한국재료학회지 Vol.28 No.9
Lead free $(1-x)(0.675BiFeO_3-0.325BaTiO_3)-xLiTaO_3$ (BFBTLT, x = 0, 0.01, 0.02, and 0.03, with 0.6 mol% $MnO_2$ and 0.4 mol% CuO) were prepared by a solid state reaction method, followed by air quenching and their crystalline phase, morphology, dielectric, ferroelectric and piezoelectric properties were explored. An X-ray diffraction study indicates that lithium (Li) and tantalum (Ta) were fully incorporated in the BFBT materials with the absence of any secondary phases. Dense ceramic samples (> 92 %) with a wide range of grain sizes from $3.70{\mu}m$ to $1.82{\mu}m$ were obtained in the selected compositions ($0{\leq}x{\leq}0.03$) of BFBTLT system. The maximum temperatures ($T_{max}$) were mostly higher than $420^{\circ}C$ in the studied composition range. The maximum values of maximum polarization ($P_{max}{\approx}31.01{\mu}C/cm^2$), remnant polarization ($P_{rem}{\approx}22.82{\mu}C/cm^2$) and static piezoelectric constant ($d_{33}{\approx}145pC/N$) were obtained at BFBT-0.01LT composition with 0.6 mol% $MnO_2$ and 0.4 mol% CuO. This study demonstrates that the high $T_{max}$ and $d_{33}$ for BFBTLT ceramics are favorable for industrial applications.
Akram, Fazli,Ahmed Malik, Rizwan,Hussain, Ali,Song, Tae-Kwon,Kim, Won-Jeong,Kim, Myong-Ho Elsevier 2018 Materials letters Vol.217 No.-
<P><B>Abstract</B></P> <P>LiTaO<SUB>3</SUB> (LT)-modified (1 − <I>x</I>)(0.675BiFeO<SUB>3</SUB>–0.325BaTiO<SUB>3</SUB>) + 0.6 mol% MnO<SUB>2</SUB> + 0.4 mol% CuO (BFBTMC–<I>x</I>LT, where <I>x</I> = 0–0.030) ceramics were synthesized by solid state reaction method. The crystal symmetry, ferroelectric response, and temperature stable dielectric properties were investigated as a function of different LT-content. The X-ray diffraction study of BFBTMC–LT piezoceramics revealed no remarkable variation in the crystal symmetry. The value of maximum polarization (<I>P</I> <SUB>m</SUB> ≈ 24 μC/cm<SUP>2</SUP>) and remnant polarization (<I>P</I> <SUB>r</SUB> ≈ 18 μC/cm<SUP>2</SUP>) were obtained at BFBTMC–0.010LT composition. The maximum temperature of permittivity (<I>T</I> <SUB>max</SUB>) decreased by the addition of LT-content in BFBTMC materials. The un-doped sample was ferroelectric; a change to relaxor behavior occurred by the addition of LT-content, with broad frequency dependent curves of dielectric mid-value permittivity (ε<SUB>rmid</SUB>) and tangent loss as a function of temperature. A significant enhancement occurred at 3 mol% LT-modified BFBTMC ceramics, with ε<SUB>rmid</SUB> = 5000 ± 9.5% (250–450 °C at 1 kHz). These results are favorable for practical applications in high temperature dielectrics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> LiTaO<SUB>3</SUB>-modified BiFeO<SUB>3</SUB>–BaTiO<SUB>3</SUB> dielectric ceramics were prepared. </LI> <LI> Easy and reproducible solid state reaction method was used. </LI> <LI> Temperature stable dielectric of 5000 ± 9.5% was achieved in the range 250–450 °C. </LI> </UL> </P>
Electromechanical properties of ternary BiFeO3−0.35BaTiO3-BiGaO3 piezoelectric ceramics
Akram, Fazli,Malik, Rizwan Ahmed,Khan, Salman Ali,Hussain, Ali,Lee, Soonil,Lee, Myang-Hwan,In, Choi Hai,Song, Tae-Kwon,Kim, Won-Jeong,Sung, Yeon Soo,Kim, Myong-Ho Springer-Verlag 2018 JOURNAL OF ELECTROCERAMICS Vol.41 No.1
Akram, Fazli,Malik, Rizwan Ahmed,Song, Tae Kwon,Lee, Soonil,Kim, Myong-Ho Elsevier 2019 Journal of the European Ceramic Society Vol.39 No.7
<P><B>Abstract</B></P> <P>The thermal stability of the dielectric behavior and the crystal structure, surface morphology, polarization, and piezoelectric properties of lead-free BiGaO<SUB>3</SUB> (BG)-modified 0.65Bi<SUB>1.05</SUB>FeO<SUB>3</SUB>–0.35BaTiO<SUB>3</SUB> (abbreviated as BF–BT–<I>x</I>BG with 0 ≤ <I>x</I> ≤ 0.03) ceramics were investigated. XRD analysis of BF–BT–<I>x</I>BG dielectric ceramics revealed no remarkable change in the crystal structure within the studied composition range. Around the critical composition (BF–BT–0.02BG), the piezoelectric constant (<I>d</I> <SUB>33</SUB>) and electromechanical coupling factor (<I>k</I> <SUB>p</SUB>) reached maximum values of ⁓205 pC/N and 34.5%, respectively. The BF–BT–BG dielectric system also exhibited a thermally-stable ε<SUB>r</SUB> (801–902, at 30 °C – 500 °C), high <I>T</I> <SUB>max</SUB> (395 °C – 416 °C), colossal ε<SUB>rmax</SUB> (46,363–76,303), and ε<SUB>rmid</SUB> (2241 ± 15%–3678 ± 15%, with tan<I>δ</I> ≤ 0.08) across a wide temperature range of 198 °C–332 °C. This improvement in the dielectric properties and high <I>T</I> <SUB>max</SUB> of the optimum specimen can be attributed to the BiGaO<SUB>3</SUB>-modification and quenching process, which made the system viable for applications that require high-temperature dielectric stability.</P>
Synthesis and mechanical characterization of alumina based composite material for armor application
Muhammad Shahid,Rizwan Ahmed Malik,Hussein Alrobei,Jaehwan Kim,Muhammad Latif,Azhar Hussaina,Muhammad Uzair Iqbal,Azeem Hafiz 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.2
This study focuses on development of advance ceramic with improved toughness which can be used as armor material forpersonnel protection. Toughness is the characteristics that defines material resistance to fracture. Ceramics are important classof materials with combination of good strength, toughness and with stand multiple-striking. In this study, three differentsamples i.e. alumina, Zirconia toughened alumina (ZTA), and alumina incorporated with SiC (SiCA); hexagonal shapesamples were made by dry pressing and sintered at 1600 oC in argon atmosphere. Microstructural characterization: SEM andOptical microscopy demonstrated fine grain size distribution in matrix phase. BSE images confirmed the presence of ZrO2particles. High porosity of about 6.35% was observed in SiCA samples. EDX analysis confirms the composition. Mechanicalcharacterization showed improved toughness at the expense of hardness. SiCA samples showed maximum value of hardnesswhile ZTA showed maximum toughness of 4.6 MPa·m1/2. The obtained properties are comparable to other ceramic materialsprepared by different methods.