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초음파 분무 열분해법에 의한 $(Zr, SN)TiO_4$ 구형 미분말의 합성
조서용,이종흔,김명철,박순자 한국세라믹학회 1994 한국세라믹학회지 Vol.31 No.5
Fine, spherical (Zr, SN)TiO4 powders were prepared from the aqueous solution of metal chlorides by ultrasonic spray pyrolysis. Single phase (Zr, SN)TiO4 powders could be obtained above $700^{\circ}C$ (=temperature of the reactor) and all powders exhibited sizes in the range of 0.1 to 2.0 ${\mu}{\textrm}{m}$ and a narrow size distribution. The sintering properties of the prepared powders were better than those of the powders from solid-state reaction.
$La(Mg_{1/2}Ti_{1/2})O_3$와 $La(Mg_{1/2}Zr){1/2})O_3$에서의 양이온 규칙과 고주파 유전특성
조서용,고경현,홍국선,박순자 한국세라믹학회 1997 한국세라믹학회지 Vol.34 No.3
1:1 복합 페로스카이트 물질인 La(Mg1/2Ti1/2)O3 and La(Mg1/2Zr1/2)O3의 양이온 규칙 존재와 고주파 유전특성을 x선 회절과 회로망분석기를 사용하여 조사하였다. 기존의 연구에서는 두 물질 모두 양이온 규칙이 없으며 입방정 구조를 갖는다고 보고되었지만, 본 연구에서의 x선 분석에서는 양이온 규칙을 나타내는 초격자회절선과 비입방정 구조를 의미하는 기본회절선의 split이 발견되었다. 고주파 영역에서의 유전율은 La(Mg1/2Ti1/2)O3의 경우 29,La(Mg1/2Zr1/2)O3는 24, 품질계수(Q*f)는 각각 73000, 49000이다. 공진주파수 온도계수는 La(Mg1/2Ti1/2)O3의 경우 - 65ppm/$^{\circ}$C,La(Mg1/2Zr1/2)O3는 -80ppm/$^{\circ}$C로 음의 값을 가진다.
$(Na_{1/2}Bi_{1/2})TiO_3-PbTiO_3$ 고용체의 강유전 상전이 거동
홍국선,조서용,박승익 한국세라믹학회 1995 한국세라믹학회지 Vol.32 No.8
The morphotropic phase boundary and phase transitions of the solid solutiion system, (1-x)(Na1/2Bi1/2)TiO3-PbTiO3+xPbTiO3 were studied by investigating changes in crystal structure, variations in permittivity with temperature, and calorimetric behavior. It was observed that the morphotropic phase boundary (MPB) of this solid solutiion system was at near 14 mol% of PbTiO3. Compositions containing less than 10mol% PbTiO3 (x<0.1) exhibited a phase transition, i.e. ferroelectric rhombohedrallongrightarrowparaelectric paraelectric cubic, with increasing temperature. Composition containing more than 14 mol% PbTiO3 (x 0.14) showed a phase transition from ferroelectric tetragonal to paraelectric cubic. In the composition range of 0.1<x<0.14 an anomaly in $\varepsilon$ (T) curve, which coincided with a phase transition from ferroelectric rhombohedral to an intermediate phase, was also found.
$La(Zn_{1/2}Ti_{1/2})O_3$의 합성 및 고주파 유전특성
서명기,조서용,홍국선,박순자 한국세라믹학회 1996 한국세라믹학회지 Vol.33 No.9
The dielectric properties at microwave frequencies of B site complex perovskite La(Zn1/2Ti1/2)O3 which has +3 ion in A site were investigated. maximum Q*F value of the specimens was 59000 dielectric constant 34, temperature coefficient of resonant frequency -52 ppm/$^{\circ}C$. XRD pattern of the sintered specimen shows (111) ssuperlattice reflection which indicates Zn and Ti cation ordering.
$Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$계 완화형 강유전체의 특성에 미치는 PbTiO3 첨가량의 영향 -II. 상전이 및 전계인가 변위특성-
박재환,김인태,김동영,조서용,흥국선,박순자 한국세라믹학회 1996 한국세라믹학회지 Vol.33 No.5
In order to understand the electrostrictive behavior of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) solid solutions the dielectric constants the electric-field-induced strains and the pyroelectric coefficients of (1-x)PMN-xPT (x=0.1-0.4) were investigated in the temperature range -50~20$0^{\circ}C$. For x=0.1~0.35 where the phase transi-tion is diffusive the strain has a maxima at the temperature of maximum pyroelectric coefficient (depolrizing temperature) rather than the temperature of maximum dielectric constant. For x=0.4 where the phase transition is relatively sharp the strain decreases monotonically as the temperature increases. Relationships among the above experimental results are discussed.