• Journal of the Korean Magnetics Society
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• v.3 no.3
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• pp.185-189
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• 1993

급속응고법으로 제작된 비정질 $Fe_{85-x}Co_{x}Zr_{7}B_{7}Cu_{1}$ 합금의 열처리에 따른 구조 및 자기특성이 조사되었다. 비정질 $Fe_{85-x}Co_{x}Zr_{7}B_{7}Cu_{1}$ 합금은 $600^{\circ}C$이하의 열처리온도에서 약 10 nm의 초미세결정립이 형성된다. $600^{\circ}C$이상의 열처리 조건에서는 결정립크기가 급격히 증가하여 자기특성을 열화시킨다. $Fe_{85-x}Co_{x}Zr_{7}B_{7}Cu_{1}$ 합금의 최적열처리온도는 Fe-Zr-B초미세결정립합금에 비하여 낮으며, 결정립크기 또한 감소한다. 이는 Cu의 첨가에 기인하는 것으로 판단된다. 최적열처리조건에서 $Fe_{80}Co_{5}Zr_{7}B_{7}Cu_{1}$ 초미세결정립합금의 포화자화 및 f=50 kHz, $B_{m}=0.2\;T$에서 측정한 투자율 및 철손은 각각 157.3 emu/g(1.5 T), $1.8{\times}10^{4}$ 및 13 W/kg으로 자기특성이 가장 우수하다.

• Journal of the Korean Magnetics Society
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• v.12 no.5
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• pp.189-194
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• 2002

Microstructure and magnetic properties of Sm-Co sintered magnet were investigated with the variation of Zr content and their solution treatment and aging temperatures. The fraction of eutectic structure and the size of eutectic area decreased with increasing x value of cast Sm(C $O_{.688-x}$F $e_{.242}$C $u_{.07}$Z $r_{x}$)$_{7.404}$ alloys. On the other hand, x=0.022 ingot had finer dendritic structure compared to the other alloys. The sintered magnet of Sm(C $O_{.688-x}$F $e_{.242}$C $u_{.07}$Z $r_{x}$)$_{7.404}$ had well defined cell structure which is composed of cell boundary Sm $Co_{5}$ and cell interior S $m_2$Co/ssub 17/ phase. Cell boundary Sm $Co_{5}$ phase has 20nm thickness and its relative angle was 120$^{\circ}$ in x=0.018 and 0.022 alloys. Cell size was decreased with increasing Zr contents. But, x=0.026 alloy has diffuse cell boundary and irregular shape compared to x=0.022 and 0.018 alloys. Maximum value of coercive force and maximum energy Product were obtained from x=0.022 alloys. Optimum solution treatment temperature of Sm(C $O_{.688-x}$F $e_{.242}$C $u_{.07}$Z $r_{x}$)$_{7.404}$ alloy was 1170 $^{\circ}C$ and 1st aging temperature of two step aging process for higher coercivity was 850 $^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.325-325
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• 2007

The perovskites in the $LaAlO_3-BaZrO_3$ system (i.e., $(1-x)LaAlO_3-xBaZrO_3$ were fabricated by a solid state reaction and their dielectric properties were investigated. For the compositions of x=0.1~0.9, the mixture of $LaAlO_3$ with a rhombohedral structure and $BaZrO_3$ with a cubic was observed when the sintering was conducted at $1500^{\circ}C$, indicating that the solubility of constituent elements was very low and a narrow solid solution region might exist. The large difference of ionic radii between $La^{3+}$ ion (0.136nm, C.N.=12) and $Ba^{2+}$ ion (0.161nm) or $Al^{3+}$ ion (0.0535nm, C.N.=6) and $Zr^{4+}$ ion (0.072nm) might hinder the mutual substitution. Within the compositions of x=0~0.7, the dielectric constant of the mixture increased with the amount of $BaZrO_3$, i.e., x value, which was in good agreement with the logarithmic mixing rule (In $_{r,i}={\Sigma}v_iln\;_{r,i}$). The increase in $BaZrO_3$ doping decreased $Q{\times}f$ value significantly due to the low $Q{\times}f$ value of $BaZrO_3$ itself, a poor microstructure of the mixture with an increased grain boundary area per volume, and defects in the cation and oxygen sub-lattices which were respectively caused by the evaporation of barium during the sintering process and the substitution of Ba on La-site or Al on Zr-site.

• Current Applied Physics
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• v.18 no.11
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• pp.1359-1367
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• 2018

In this work, we investigated the spectroscopic properties of $LiY_xSr_yZrO_{3+{\alpha}:Eu^{3+}$, a red emitting nanophosphor based on $SrZrO_3$ perovskite. The synthesis process was an auto-combustion process. X-ray diffractograms show the orthorhombic structure of $SrZrO_3$. Photoluminescence (PL) excitation spectra display a split charge transfer band revealing the presence of two possible sites for the $Eu^{3+}$ ions. The emission spectra at 231 nm excitation illustrate the dominance of the $^5D_0-^7F_1$ transition, which is an indication that the smaller sized $Eu^{3+}$ ions are mostly situated at the more ordered (symmetric) $Sr^{2+}$ sites. The emission spectra at 292 nm & 397 nm excitations show the dominance of $^5D_0-^7F_2$ transition which suggests some of the $Eu^{3+}$ ions are also situated at the distorted $Zr^{4+}$ sites. Both the intensity parameters, asymmetry ratio and the decay lifetimes of the nanophosphors show dependence on $Y^{3+}$ concentration, signifying a modification in the host structure. Maximum quantum efficiency value of ${\approx}46%$ was obtained for the nanophosphors which indicate the need for improvement for practical applications. CIE coordinates show the suitability of this phosphor for both red emission in LED and as a complementary colour for white LED applications.

• Journal of the Korean Ceramic Society
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• v.32 no.5
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• pp.535-542
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• 1995

The effect of sintering temperature, sintering time and forming pressure on microwave dielectric properties of (Zr1-xSnx)TiO4 ceramics containing 1.0wt% B2O3, 0.3 wt% La2O3 and 1.0wt% NiTa2O6 was investigated using the response surface methodology. The optimum values of processing variables were determined based on the reproducibility. The optimum values of the dielectric constant of >35. Q.f0 of >55000 and $\tau$f=$\pm$5 ppm/$^{\circ}C$ could be obtained when the sample was pressed at 500~600kg/$\textrm{cm}^2$ and sintered at 1500~155$0^{\circ}C$ for 2~3 hrs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.391-395
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• 2000

In this study, the temperature coefficient of resonant frequency(TC $F_{r}$), dielectric and piezoelectric properties of Pb[(S $b_{1}$2/N $b_{1}$2/)$_{0.0035}$-(M $n_{1}$3/N $b_{2}$3/)$_{0.0065}$-(Z $r_{x}$ $Ti_{1-x}$ )$_{0.90}$] $O_3$ceramics is investigated with Zr/Ti ratio. The dielectric constant and electromechanical coupling factor( $k_{p}$) showed the highest values of 1257, 0.562 respectively when the Zr/Ti ratio is 49.5/50.5. The mechanical quality factor( $Q_{m}$) is the lowest value of 713 when the Zr/Ti ratio is 49.5/50.5, and increased with the decrease of the Zr/Ti ratio. The temperature coefficient of resonant frequency(TC $F_{r}$) change abruptly at the morphotropic phase boundary(MPB), which is between the rhombohedral phase with highly negative TC $F_{r}$ of -106ppm/$^{\circ}C$ and the tetragonal phase with highly positive TC $F_{r}$ of +64pp $m^{\circ}C$ as Zr/Ti ratio changes from 50/50 to 49.5/50.5.50.5..5.50.5.5.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.428-433
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• 2003

In this study, we investigated the variation of microstructural and electromagnetic properties of YIG ferrites for Isolator/Circulator application with the sintering temperature and Zr addition. The composition of the ferrites was Y$_{2.1}$Ca$_{0.9}$Fe$_{4.4-x}$V$_{0.5}$In$_{0.05}$Al$_{0.05}$Zr$_{x}$O$_{12}$ with x=0, 0.05, 0.1 and 0.2. The YIG ferrites were prepared by the conventional ceramic sintering process. The Zr-substituted YIG ferrite, Y$_{2.1}$ Ca$_{0.9}$Fe$_{4.4-x}$V$_{0.5}$In$_{0.05}$Al$_{0.05}$ Zr$_{x}$O$_{12}$ showed the highest saturation magnetization (1097 gauss) at x=0.1. The microwave properties were shown as isolation of 18.60 dB and insertion loss of 0.45 dB at x=0.2. Additionally, Zr-substitution was effective in decreasing ferromagnetic resonance linewidth with Zr content.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.487-490
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• 1995

With the object of developing a new magnetic core materials for high frequency use, the crystallization behaviors and the soft magnetic properties of amorphous $F_{86-x}Al_{4}B_{10}Zr_{x}\;(5{\leq}x{\leq}10\;at%)$ alloys subjected to annealing treatment at wide temperature range were investigated. For optimally annealed $Fe_{86-x}Al_{4}B_{10}Zr_{x}$ alloys in amorphous state, rather good soft magnetic properties of ${\mu}_{e}=17000~25000,\;H_{c}=20~30$ mOe and $B_{10}{\geq}0.6$ T are obtained. However, as the alloys crystallize, the soft magnetic properties are largely dergely deteriorated, which is attributed principally to the narrow temperature gap between $T_{x1}$ and $T_{x2}$, which allows the nearly co-precipitation of bcc phase and Fe-B compounds in incipient crystallization stage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.208-209
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• 2006

Sinterability and microwave dielectric properties of the $Zr1-x(Zn_{1/3}Nb_{2/3})xTiO_4$(x=4, 6) system ceramics have been investigated as functions of zinc-borosilicate(ZBS) glass contents and amount of $Zn_{1/3}Nb_{2/3}O_2$ substitution with a view to applying the composition to LTCC technology. The addition of 25 wt% ZBS glass ensured successful sintering below $925^{\circ}C$. With increasing ZBS glass and $Zn_{1/3}Nb_{2/3}O_2$ contents increased dielectric constant and sinterability but addition ZBS glass decreased the quality factor significantly due to the formation of an excessive liquid and second phases. The sintered $Zr4(Zn_{1/3}Nb_{2/3})6TiO_4$ system ceramics at $925^{\circ}C$ with 25 wt% ZBS glass demonstrated 27.7 in dielectric constant (${\varepsilon}_r$), 3,850 m quality factor($Q{\times}f_0$), and +6 ppm/$^{\circ}C$ in temperature coefficient of resonant frequency($\tau_f$).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.127-137
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• 2019

Zr electrorefining is demonstrated herein using Zirlo tubes in a chloride-fluoride mixed molten salt in the presence of $AlF_3$. Cyclic voltammetry reveals a monotonic shift in the onset of metal reduction kinetics towards positive potential and an increase in intensity of the additional peaks associated with Zr-Al alloy formation with increasing $AlF_3$ concentration. Unlike the galvanostatic deposition mode, a radial plate-type Zr growth is evident at the top surface of the salt during Zr electrorefining at a constant potential of -1.2 V. The diameter of the plate-type Zr deposit gradually increases with increasing $AlF_3$ concentration. Scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) analyses for the plate-type Zr deposit show that trace amount of Al is incorporated as Zr-Al alloys with different chemical compositions between the top and bottom surface of the deposit. Addition of $AlF_3$ is effective in lowering the residual salt content in the deposit and in improving the current efficiency for Zr recovery.