Purge & Trap-GC를 이용한 의약품 필름코팅 정제 중 잔류용제에 관한 연구

장준식,이명자,소유섭,문춘선,이주헌,박희라,김진숙,강경모,이선옥,방성연,유미자,유문균,금오성,이병욱 식품의약품안전청 2000 식품의약품안전청 연보 Vol.4 No.-

의약품은 약물을 생체에 적풋하기 위하여 유효성분의 효과가 언제나 일정하게 확보되고 사응에 편리하도록 만들어지는 것이므로 유효썽분 이외에 약효에 영향을 주지 않는 성분이 첨가되는 경운가 많다. 이 때 사용되는 용매들은 제피의 광택 및 건쪼시간의 단축 등을 위하여 휘발점이 낮을 용매들이 주로 사용되어진다. 본 연구는 의약품 필름코팅정제 중 잔류용매 4종(chlorofonr benzen, trichloro ethylen, 1,4-dioxane)에 대한 변형된 pirge & trap-GC 장치를 이용한 동시분석방법을 개발하였으며, 각 표준품의 RSD 값은 chloroform 3.03%, benzen 3.17%, trichloroethylen 3.69% and 1,4-dioxane 3.41%였다. 또한 시중 유통중인 의약품 50종에 대하여 잔류웅매 양을 측정하였으며, 검출되는 잔류용매는 한 건도 없었다. This study nras carried out to develope the analytical method for the mixture of chlorefonn, benzen, trichloroethylen and 1,4-dioxane simultaneously and determine the remainingorgauic solvents in coating tablets by Purge & Trap-GC. The results were as follouFs ; 1. Chloroform, benzen, trio:tloroethylen and 1,4-dioxane separated by tenax #5 trap by HP-624GC column by terrlperature programming. The peaks were separated completely at retentiontime of 6.88min for chloroform, 8.21min for benzen, 10.38miu for trichloroethylen and 11.95minfor 1,4-dioxane. 2. Standard RSD were individually chloroform 3.03%, benzen 3.17%, trichloroethylen 3.69%and 1,4-diorane 3.41%. 3. 60 samples were not detrcted chloroform, benzen, trichloroethylen and 1,4-dioxane.

Antifungal Activity of Streptomyces pad anus isolate TH04 against Monilinia fructicola, Brown rot Fungus on Stone-fruits

임태헌,최용화,이동운,한상섭,차병진,Lim, Tae-Heon,Choi, Yong-Hwa,Lee, Dong-Woon,Han, Sang-Sub,Cha, Byeong-Jin The Korean Society of Pesticide Science 2008 농약과학회지 Vol.12 No.3

복숭아 미이라 과일로부터 복숭아 잿빛무늬병 Monilinia fructicola에 대하여 강한 항균활성을 보이는 방선균 Streptomyces padanus TH04를 분리하였다. TH04 균주의 배양 추출물 1%를 함유한 배지에서의 균사생육 및 포자발아는 시험한 M. fructicola의 strain에 따라 각각 $79.8{\sim}81%$와 $73.9{\sim}75.8%$ 억제되었다. 병원균과 TH04 균주 초기접종 밀도를 0.01%, 0.1% 및 1%로 달리하여 동시배양 한 결과, 항균활성은 선발 방선균의 밀도에 따라 $7.5%{\sim}94%$로 나타났다. 사과(품종; 후지)를 이용한 조추출물의 항균활성은 0.1% 처리구 85.9%, 1%처리구 100%로 나타났다. 항균활성 물질 생산, 안정성 및 제형화에 관한 연구가 이루어질 경우 선발한 Streptomyces padanus TH04는 생물학적 방제제로의 개발 가능성 있을 것으로 생각된다. The Streptomyces padanus isolate TH04, isolated from mummified peaches, showed strong antifungal activity to Monilinia fructicola. The inhibition activity of the isolate TH04 to mycelial growth and spore germination at 1% concentration of sub-antifungal powder made from culture suspension (CS) was ranged from 79.8% to 81.0% and from 73.9% to 75.8% to M. fructicola four strains, respectively. In the test of antifungal activity in mixed culture of the isolate and M. fructicola, inhibition rate was 7.5%, 86.8% and 94.0% in 0.01, 0.1, and 1% concentration of CS containing bacterial cell of the isolate, respectively. On apples (cultivar; Fuji), the control values of the isolate TH04 crude filtrates (0.1 and 1%) were 85.9% and 100%, respectively. The results suggest that the isolate TH04 indicate development possibility as biocontrol agent of brown rot caused by M. fructicola with the study on delivery method and fermentation condition to produce an antifungal compound.

Reduction and oxidation performance evaluation of manganese-based iron, cobalt, nickel, and copper bimetallic oxide oxygen carriers for chemical-looping combustion

Sub Kwak, Byeong,Park, No-Kuk,Ryu, Ho-Jung,Baek, Jeom-In,Kang, Misook Elsevier 2018 Applied Thermal Engineering Vol.128 No.-

<P><B>Abstract</B></P> <P>Transition metal oxides like Fe<SUB>2</SUB>O<SUB>3</SUB>, Co<SUB>3</SUB>O<SUB>4</SUB>, NiO, and CuO have mainly been used in the chemical-looping combustion (CLC) reaction as oxygen carrier particles because of their outstanding performances due to high reduction potential. However, monometal oxides have a serious problem of rapid deactivation due to agglomeration between each particle after several redox cycles. In order to solve this problem, bimetal oxides based on Mn, which undergoes no deactivation, were synthesized. Mn-based bimetal oxygen carrier particles Fea-Mnb-Ox, Coa-Mnb-Ox, Nia-Mnb-Ox, and Cua-Mnb-Ox were synthesized by using a sol–gel method. The range of a and b in the particle label obtained in this study is 0.5–2.5, depending on the metal content added. The chemical and physical properties of the prepared particles were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), CH<SUB>4</SUB>-/CO-temperature programmed desorption, and thermogravimetric analysis (TGA). The XRD results showed that the prepared particles comprised two- or three-phase mixed metal oxides. The Fe2.0-Mn1.0-Ox particle was in the phases of Fe<SUB>2</SUB>Mn<SUB>1</SUB>O<SUB>4</SUB> and Fe<SUB>20.16</SUB>Mn<SUB>11.84</SUB>O<SUB>48</SUB>, respectively, and the Co2.0-Mn1.0-Ox particle had the phase of Co<SUB>2</SUB>Mn<SUB>1</SUB>O<SUB>4</SUB>. In addition, Ni2.0-Mn1.0-Ox particle has NiO and Ni<SUB>1</SUB>Mn<SUB>2</SUB>O<SUB>4</SUB> phases, and Cu2.0-Mn1.0-Ox particle exist in the phases of CuO, Cu<SUB>2</SUB>O and Cu<SUB>1</SUB>Mn<SUB>1</SUB>O<SUB>2</SUB>, respectively. The distributions of added elements on the particles were observed from the SEM mapping results. The oxygen carrier capacities of the particles were tested by isothermal H<SUB>2</SUB>/air and CH<SUB>4</SUB>/air redox cycle experiments using TGA at 850°C. The improved results obtained in this study revealed that the Cu2.0-Mn1.0-Ox particle was an enhanced bimetal oxide oxygen carrier for CLC under CH<SUB>4</SUB>/air conditions. In particular, among the synthesized particles, the Cu2.0-Mn1.0-Ox particle stably showed 16.7wt% oxygen transfer capacity over 10 redox cycle under CH<SUB>4</SUB>/air at 850°C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Redox performance for Ma-Mnb-Ox (M=Fe, Co, Ni, and Cu) investigated in detail. </LI> <LI> The highest redox performance (16.7wt%) was observed for Cu2.0-Mg1.0-Ox. </LI> <LI> The Cu2.0-Mn1.0-Ox sample was stable up to 10 reaction cycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Redox reaction on the Cua-Mnb-Ox for the chemical looping combustion.</P> <P>[DISPLAY OMISSION]</P>

Bi_1/2Na_1/2TiO₃-BiAlO₃ 무연 압전 세라믹스의 유전 및 전기 기계적 변형 특성에 대한 SrTiO₃ 첨가 효과

이상섭,이창헌,즈엉 짱 안,김동혁,김병우,한형수,이재신,Lee, Sang Sub,Lee, Chang-Heon,Duong, Trang An,Kim, Dong Hyeok,Kim, Byeong Woo,Han, Hyoung-Su,Lee, Jae-Shin 한국재료학회 2021 한국재료학회지 Vol.31 No.10

(Bi_1/2Na_1/2)TiO₃ (BNT)-based ceramics are considered promising candidates for actuator application owing to their excellent electromechanical strain properties However, to obtain large strain properties, there remain several issues such as thermal stability and high operating fields. Therefore, this study investigates a reduction of operating field in (0.98-x)Bi_1/2Na_1/2TiO₃-0.02 BiAlO₃-xSrTiO₃ (BNT-2BA-100xST, x = 0.20, 0.21, 0.22, 0.23, and 0.24) via analyses of the microstructure, crystal structure, dielectric, polarization, ferroelectric and electromechanical strain properties. The average grain size of BNT-${\underline{2}}$BA-100xST ceramics decreases with increasing ST content. Results of polarization and electromechanical strain properties indicate that a ferroelectric to relaxor state transition is induced by ST modification. As a consequence, a large electromechanical strain of 592 pm/V is obtained at a relatively low electric field of 4 kV/mm in 22 mol% ST-modified BNT-2BA ceramics. We believe that the materials synthesized in this study are promising candidates for actuator applications.

Synthesis of basalt fiber@Zn_1-xMg_xO core/shell nanostructures for selective photoreduction of CO₂ to CO

Kwak, Byeong Sub,Kim, Kang Min,Park, Sun-Min,Kang, Misook Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.407 No.-

<P><B>Abstract</B></P> <P>This study focused on the development of a catalyst for converting carbon dioxide, the main cause of global warming, into a beneficial energy source. Core@shell structured particles, BF@ZnO and BF@Zn<SUB>1-x</SUB>Mg<SUB>x</SUB>O, are synthesized in order to selectively obtain CO gas from the photoreduction of CO<SUB>2</SUB>. A modified sol-gel process is used to synthesize the core@shell structures with a three-dimensional microstructure, which are subsequently characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDAX), ultraviolet (UV)–vis absorption, photoluminescence (PL), and photocurrent density analysis. The CO<SUB>2</SUB> adsorption abilities of the core@shell particles are estimated through CO<SUB>2</SUB>-temperature programmed desorption (TPD). The core@shell structured BF@Zn<SUB>1-x</SUB>Mg<SUB>x</SUB>O particles including the Mg ingredient significantly increased the adsorption of CO<SUB>2</SUB> gas at the microfiber/nanoparticle interface. Both the BF@ZnO and BF@Zn<SUB>1-x</SUB>Mg<SUB>x</SUB>O particles selectively reduce the carbon dioxide to carbon monoxide, with almost no other reduced products being observed. These results are attributed to the effective adsorption of CO<SUB>2</SUB> gas and inhibited recombination of the photogenerated electron–hole pairs. BF@Zn<SUB>0.75</SUB>Mg<SUB>0.25</SUB>O exhibited superior photocatalytic behavior and selectively produced 5.0μmolg<SUB>cat</SUB> <SUP>−1</SUP> L<SUP>−1</SUP> of CO gas after 8h of reaction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnO and Zn<SUB>1-x</SUB>Mg<SUB>x</SUB>O crystals were grown onto the BFs. </LI> <LI> The core@shell structured BF@Zn<SUB>1-x</SUB>Mg<SUB>x</SUB>O particles significantly increased the adsorption of CO<SUB>2</SUB> gas. </LI> <LI> The BF@ZnO or BF@Zn<SUB>1-x</SUB>Mg<SUB>x</SUB>O particles selectively reduce the carbon dioxide to carbon monoxide. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Improvement of reduction and oxidation performance of MMgOx (M=Fe, Co, Ni, and Cu) particles for chemical looping combustion

Kwak, Byeong Sub,Park, No-Kuk,Baek, Jeom-In,Ryu, Ho-Jung,Kang, Misook Elsevier 2017 Powder technology Vol.312 No.-

<P><B>Abstract</B></P> <P>The objective of this study was to use Mg to improve the performance in chemical looping combustion. Oxygen carrier particles were synthesized in which Mg was doped into the M-sites with Fe, Co, Ni, and Cu to produce FeaMgbOx, CoaMgbOx, NiaMgbOx, and CuaMgbOx, respectively, with M/Mg ratios ranging from 1.5 to 3.0. The structure and properties of the prepared samples were characterized using XRD, SEM, CH<SUB>4</SUB>-/CO-TPD, XPS, and TGA. The XRD results explore that the Fe2Mg1Ox sample has a pure cubic structure of Fe<SUB>2</SUB>MgO<SUB>4</SUB>, whereas the Co2Mg1Ox and Ni2Mg1Ox samples exist as a solid solution. Nevertheless, the mixed compound formation of orthorhombic structure of Cu<SUB>2</SUB>MgO<SUB>3</SUB> and cubic structure of MgO has been observed in Cu2Mg1Ox. The CH<SUB>4</SUB> absorption is the highest on the Cu2Mg1Ox sample according to the CH<SUB>4</SUB>-TPD results. The CO-TPD and H<SUB>2</SUB>–TPR results showed that the adsorption of the Cu and Mg complex metal oxide is higher than that of the pure metal oxide. The oxygen carrier capacity of the samples was studied by isothermal H<SUB>2</SUB> (FR)/air (AR) and CH<SUB>4</SUB> (FR)/air (AR) redox cycle experiments at 850°C using TGA. The promising results obtained from chemical looping combustion indicate that the CuaMgbOx samples are potentially useful for CLC in H<SUB>2</SUB> and CH<SUB>4</SUB> atmospheres.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Redox performance for MaMgbOx (M=Fe, Co, Ni, and Cu) was investigated in detail. </LI> <LI> The highest redox performance (15.29wt%) was observed for Cu2.0Mg1.0Ox. </LI> <LI> The Cu2.0Mg1.0Ox sample was stable up to 10 reaction cycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Redox reaction on the M2.0Mg1.0Ox (M=Fe, Co, Ni, and Cu) for the chemical looping combustion.</P> <P>[DISPLAY OMISSION]</P>

Reliable oxygen transfer in MgAl₂O₄ spinel through the reversible formation of oxygen vacancies by Cu²⁺/Fe³⁺ anchoring

Do, Jeong Yeon,Son, Namgyu,Park, No-Kuk,Kwak, Byeong Sub,Baek, Jeom-In,Ryu, Ho-Jung,Kang, Misook Elsevier 2018 APPLIED ENERGY Vol.219 No.-

<P><B>Abstract</B></P> <P>This study focused on Cu<SUB>x</SUB>Mg<SUB>1-x</SUB>Fe<SUB>y</SUB>Al<SUB>2-y</SUB>O<SUB>4</SUB> oxygen carriers for application in the chemical looping combustion of methane. Cu<SUB>x</SUB>Mg<SUB>1-x</SUB>Fe<SUB>y</SUB>Al<SUB>2-y</SUB>O<SUB>4</SUB> was fabricated by simultaneously substituting Mg<SUP>2+</SUP> and Al<SUP>3+</SUP> with Cu<SUP>2+</SUP> and Fe<SUP>3+</SUP> in the spinel structure of MgAl<SUB>2</SUB>O<SUB>4</SUB>. As a result, a great synergistic effect was observed: Cu<SUB>0.75</SUB>Mg<SUB>0.25</SUB>Fe<SUB>1.5</SUB>Al<SUB>0.5</SUB>O<SUB>4</SUB> exhibited 7.85% oxygen transfer capacity in the CH<SUB>4</SUB>-CO<SUB>2</SUB>/air redox system. Methane and carbon monoxide were significantly adsorbed on the surface of the Cu<SUB>x</SUB>Mg<SUB>1-x</SUB>Fe<SUB>y</SUB>Al<SUB>2-y</SUB>O<SUB>4</SUB> particles. Cyclic voltammetry studies predicted the active lifetime of the oxygen carrier, which had not been reported until now. Cu<SUB>0.75</SUB>Mg<SUB>0.25</SUB>Fe<SUB>1.5</SUB>Al<SUB>0.5</SUB>O<SUB>4</SUB> was expected to exhibit the greatest oxygen transfer capacity after 300 redox cycles and maintain an oxygen transfer efficiency of 92% until the 1000th redox cycle in the H<SUB>2</SUB>-N<SUB>2</SUB>/air redox system. This study concluded that the active metal species, containing Cu<SUP>2+</SUP> and Fe<SUP>3+</SUP> ions, were stably anchored in the spinel structure; this led to the reversible formation of oxygen vacancies in the spinel structure, resulting in an excellent oxygen transfer capacity that could be maintained for a long time.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu<SUB>x</SUB>Mg<SUB>1-x</SUB>Fe<SUB>y</SUB>Al<SUB>2-y</SUB>O<SUB>4</SUB> spinel structured oxygen carriers were successfully prepared. </LI> <LI> Reversible oxygen vacancies were observed in a Cu<SUB>x</SUB>Mg<SUB>1-x</SUB>Fe<SUB>y</SUB>Al<SUB>2-y</SUB>O<SUB>4</SUB> spinel structure. </LI> <LI> CH<SUB>4</SUB> and CO gases were much adsorbed on the surface of Cu<SUB>0.75</SUB>Mg<SUB>0.25</SUB>Fe<SUB>1.5</SUB>Al<SUB>0.5</SUB>O<SUB>4</SUB> spinel particle. </LI> <LI> The greatest oxygen transfer in Cu<SUB>0.75</SUB>Mg<SUB>0.25</SUB>Fe<SUB>1.5</SUB>Al<SUB>0.5</SUB>O<SUB>4</SUB> particle was obtained. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Reliable oxygen transfer in MgAl<SUB>2</SUB>O<SUB>4</SUB> spinel through the reversible formation of oxygen vacancies by Cu<SUP>2+</SUP>/Fe<SUP>3+</SUP> anchoring.</P> <P>[DISPLAY OMISSION]</P>

Effective hydrogen production from ethanol steam reforming using CoMg co-doped SiO₂@Co_1−xMg_xO catalyst

Kim, Kang Min,Kwak, Byeong Sub,Im, Younghwan,Park, No-Kuk,Lee, Tae Jin,Lee, Sang Tae,Kang, Misook Elsevier 2017 Journal of industrial and engineering chemistry Vol.51 No.-

<P><B>Abstract</B></P> <P>In this study, the activities of core@shell-structured SiO<SUB>2</SUB>@Co<SUB>1−x</SUB>Mg<SUB>x</SUB>O catalysts in ethanol steam reforming (ESR) were investigated, and the promotion effect of Mg upon H<SUB>2</SUB> production was assessed. The loading of SiO<SUB>2</SUB>@CoO with Mg resulted in an increase in ethanol conversion and H<SUB>2</SUB> yield with the concomitant suppression of carbon coke deposition and CO emission. Oxygen transfer from the MgO supporter (or improver) to the main cobalt catalytic species during ESR might play a role in maintaining the partially oxidized Co state. In longevity tests, the SiO<SUB>2</SUB>@Co<SUB>1−x</SUB>Mg<SUB>x</SUB>O core@shell material, despite being reused three times, exhibited superior H<SUB>2</SUB> production for 100h without structural collapse or coke formation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The core@shell structured SiO<SUB>2</SUB>@Co<SUB>1−x</SUB>Mg<SUB>x</SUB>O was prepared. </LI> <LI> CO-WGS on the core@shell structured SiO<SUB>2</SUB>@Co<SUB>1−x</SUB>Mg<SUB>x</SUB>O was promoted. </LI> <LI> Carbon coke deposition was suppressed by Mg loading. </LI> <LI> Both Co<SUP>0</SUP> and Co<SUP>2+</SUP> played the active sites on SiO<SUB>2</SUB>@Co<SUB>1−x</SUB>Mg<SUB>x</SUB>O. </LI> <LI> SiO<SUB>2</SUB>@Co<SUB>1−x</SUB>Mg<SUB>x</SUB>O exhibited high hydrogen production. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of acidity on the performance of a Ni-based catalyst for hydrogen production through propane steam reforming: K-AlSi_<i>x</i>O_<i>y</i> support with different Si/Al ratios

Do, Jeong Yeon,Kwak, Byeong Sub,Park, No-Kuk,Lee, Tae Jin,Lee, Sang Tae,Jo, Seung Won,Cha, Moon Soon,Jeon, Min-Kyu,Kang, Misook Pergamon Press 2017 International journal of hydrogen energy Vol.42 No.36

<P><B>Abstract</B></P> <P>Propane steam reforming (PSR) for the production of H<SUB>2</SUB> was catalyzed by a NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalyst synthesized with various Si/Al ratios (Si/Al = 0, 0.3, 0.5, 0.7, and 1.0). The effect of the Si/Al ratio on the acidity of the NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalyst for PSR was investigated. NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> gave a higher H<SUB>2</SUB> selectivity and stability during PSR than NiO/K-SiO<SUB>2</SUB> and NiO/K-Al<SUB>2</SUB>O<SUB>3</SUB>. The NH<SUB>3</SUB>-TPD results showed that the acid quantity and strength of NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> changed significantly depending on the Si/Al ratio. With an increased Si/Al ratio, the densities of both weak and strong acid sites increased. The C<SUB>3</SUB>H<SUB>8</SUB>- and CO-TPD results indicated that desorption amounts increased significantly in all NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalysts relative to those of NiO/K-SiO<SUB>2</SUB> and NiO/K-Al<SUB>2</SUB>O<SUB>3</SUB>, and the adsorption amount increased with the Si/Al ratio. PSR results showed that the NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalyst exhibited much better stability than the NiO/K-SiO<SUB>2</SUB> and NiO/K-Al<SUB>2</SUB>O<SUB>3</SUB> catalysts. This study confirms the following facts: when the acidity is appropriately adjusted for the catalyst, adsorption of the reaction gas increases, which eventually increases the reaction rate and also inhibits strong sintering between the nickel and the Al<SUB>2</SUB>O<SUB>3</SUB> support. As a result, deterioration of the catalyst can be reduced.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalyst was synthesized for the production of H<SUB>2</SUB> from PRS. </LI> <LI> The acid quantity and strength of NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> changed significantly depending on the Si/Al ratio. </LI> <LI> The adsorptions of C<SUB>3</SUB>H<SUB>8</SUB> and CO increased with the Si/Al ratio. </LI> <LI> The NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalyst exhibited much better stability during PSR. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhancement of electromechanical properties in lead-free (1-x)K_0.5Na_0.5O_3-xBaZrO₃3 piezoceramics

( Trang An Duong ),( Hoang Thien Khoi Nguyen ),( Sang-sub Lee ),( Chang Won Ahn ),( Byeong Woo Kim ),( Jae Shin Lee ),( Hyoung Su Han ) 한국센서학회 2021 센서학회지 Vol.30 No.6

This study analyzes the phase transition behavior and electrical properties of lead-free (1-x)K_0.5Na_0.5NbO_3-xBaZrO₃ (KNN-100xBZ) piezoelectric ceramics. The stabilized crystal structures in BaZrO₃-modified KNN ceramics is clarified to be pseudocubic. The polymorphic phase transition from the orthorhombic to pseudocubic phases can be observed with KNN-6BZ ceramics considering the optimized piezoelectric constant (d₃₃). Electromechanical strain behaviors are discussed. Accordingly, the enhancement of strain value at x = 0.08 (composition) may originate from the coexistence of ferroelectric domains and polar nanoregions. A schematic of domains for KNN, KNN-8BZ, and KNN-15BZ ceramics has been proposed to describe the relationship between the stabilized relaxor and changes in electrical properties.