Cu-Zn-MG Ferrite의 자기적 특성에 미치는 소결온도의 영향

고재귀 崇實大學校 2000 論文集 Vol.30 No.1

The basic composition of Cu-Zn-Mg ferrite was CuxZnyMgz Feu0₄(x+y+z+u=1) Small amounts of additives such as 0.13 mol % NiO and 0.01 mol% CaC0₃were added to the basic composition of Cu-Zn-Mg ferrite. Specimens were sintered at different temperature at (1030℃, 1050℃, 1070℃) for 2.0 hours in air and followed by air cooling. The effect of the sintered temperature on the physical properties such as inductions, coercive forces, intial permeabilities, loss factors, curie emperature, etc. of Cu-Zn-Mg ferrite have been investigated. The physical properties obtained from the aforementioned Cu-Zn-Mg ferrite specimens are found out to be in 887 gauss for the residual induction, 2.0 oersted for the coercive force, 350 for the initial permeability, 75 for the Q value, etc. in this study. These physical properties indicate that the specimens can be utilized as the core of intermediated frequency transformer in the amplitude modulation, etc..

Weinberg-Salam 모형에서 弱力子의 生成

고재걸,김귀년,김재원 경북대학교 교육대학원 1985 논문집 Vol.17 No.-

We caclulated the production and decay rates for the intermediate vector bosons (W,Z) in Winberg-Salam model. And we presented the differential cross sections for the processes e^+e^-→W^+W^-, e^+e^-→ZZ and e^+e^-→γZ in e^+e^-CM frame. Using these expressions we discussed the possibility of the event rate for the reactions.

첨가제가 Mn-Zn 페라이트의 자기적 성질에 미치는 효과

이명호,김민경,고재귀,송승기 명지대학교 자연과학연구소 2004 자연과학논문집 Vol.23 No.-

우리 연구는 첨가제가 페라이트에 미치는 효과를 연구하기 위해 두 종류의 서로 다른 금속이온을 첨가제로 한 Mn-Zn 페라이트 시료를 제작하여 이들의 자기적 성질을 비교 분석하였다. 시료 제작에 사용된 Mn-Zn 페라이트의 주 원료 조성비는 31 mol% MnO, 16 mol% ZnO 그리고 53 mol% Fe_(2)O_(3)이다. 볼밀 작업을 통해 주 원료를 잘 혼합한 후 950℃에서 3시간 동안 하소하였다. 하소된 재료에 실험에 필요한 첨가물을 혼합한 뒤 성형과정을 거쳐 1300℃에서 3시간 동안 소결하였다. 첨가물은 0.1 wt% Na_(2)SiO_(3)만을 사용한 경우 (Sample 1)와 0.05 wt% Na_(2)SiO_(3), 0.1 wt% CaO와 0.05 wt% Al_(2)O_(3)를 첨가한 (Sample 2) 두 종류의 첨가제를 이용하였다. 두 시료에 대한 자성 특성을 측정한 결과 Sample 2 시료가 Sample 1에 비해 포화자속밀도(saturation flux density) B_(8)는 더 커진 반면 잔류자속밀도(residual flux density) B_(1)과 보자력(coercive force) H_(6)는 더 적어졌음을 확인하였다. 또한 고주파 측정에서도 0.05 wt% Na_(2)SiO_(3), 0.1 wt% CaO와 0.05 wt% Al_(2)O_(3)가 첨가된 시료에서 주파수 증가에 따르는 자기손실이, 다른 시료에 비해, 매우 완만하게 증가하는 것을 관찰하였다. 이들 자기 측정으로부터 0.05 wt% Na_(2)SiO_(3), 0.1 wt% CaO와 0.05 wt% Al_(2)O_(3)의 첨가제가 Mn-Zn 페라이트의 연자성 특성을 향상시켯음을 확인하였고, 이 결과는 이들 첨가물이 소결(sintering)과정에 관하여 Mn-Zn 페라이트 미세구조의 치밀화와 입자성장을 촉진시키는 효과가 있음을 보인다. We prepared two kinds of Mn-Zn ferrites composed of 31 mol% MnO, 16 mol% ZnO and 53 mol% Fe_(2)O_(3) as a main material. These were well mixed in a ball-milling machine and calcinated at 950℃ for 3 hours. After being mixed with two kinds of additives of 0.1 wt% Na_(2)SiO_(3) (Sample 1) and 0.05 wt% Na_(2)SiO_(3), 0.1 wt% CaO and 0.05 wt% Al_(2)O_(3) (Sample 2) respectively, the materials were molded and sintered at 1300℃ for 3 hours. The sample 2 was found to have more saturation flux density, and less residual flux density and coercive force than the other one, which means that the sample 2 is more suitable for soft-magnetic material. When the samples were applied by AC magnetic field in the frequency range of 10 kMz~1 MHz, both have shown relatively stable initial permeabilities up to 1 MHz. On the other hand, the loss factof of sample 2 became less than that of sample 1 in the high frequency range above 100 kHz although there was no much difference in the resistivity of both samples through the frequency change, which suggests the additives in the sample 2 has suppressed the viscosity loss in the high frequency range. We conclude that the 0.05 wt% Na_(2)SiO_(3), 0.1 wt% CaO and 0.05 wt% Al_(2)O_(3) additives has promoted coarsening and densification of the microstructure of the Mn-Zn ferrite and resulted in the better quality of the Mn-Zn ferrite

B_(2)O_(3)를 첨가한 Ni-Cu-Zn Ferrite의 자성에 대한 소결온도 효과

김민경,이명호,고재귀,송승기 명지대학교 자연과학연구소 2005 자연과학논문집 Vol.24 No.-

B_(2)O_(3)가 첨가된 Ni-Cu-Zn 페라이트의 소결온도 변화에 따른 자기적 성질을 연구하였다. 실험에 사용한 시료는 0.1 wt%의 B_(2)O_(3)를 (Ni_(0.204)Cu_(0.204)Zn_(0.612))Fe_(1.198)O_(2.98)에 첨가하여 각각 1000℃, 1100℃ 그리고 1200℃으로 4시간 동안 소결시켜 제작했다. 시료의 자기적 성질은 X-ray 회절 패턴, 자기이력 곡선, 초투자율, 손실계수 그리고 비저항을 측정하여 연구하였다. 자기이력 곡선과 초투자율 측정 결과로부터 세 시료 모두 우수한 연자성체가 되었음을 확인하였고, 소결온도가 높을수록 coercive force(H_(c))의 감소와 초투자율의 증가가 관찰되었다. 특히 가장 높은 온도(1200℃)로 소결한 시료의 Hc는 0.217Oe이었고, 초투자율은 전 영역의 주파수에 걸쳐 가장 큰 값을 유지하였다. 전력손실은 1 ㎑~10 ㎒ 주파수 영역의 교류에 대해 시료 모두 안정된 값을 갖고, 1200℃로 소결된 시료의 전력손실과 비저항은 시료 중 가장 적은 값을 가졌다. We have studied the dependence of B-doped Ni-Cu-Zn ferrite on sintering temperature. The samples were prepared from 0.1 wt% B_(2)O_(3)-doped (Ni_(0.204)Cu_(0.204)Zn_(0.612))Fe_(1.198)O_(2.98) ferrites and sintered at 1000℃, 1100℃ and 1200℃ for 4 hours respectively. The crystal structures of the samples were identified by X-ray diffraction pattern, and the magnetic properties of those were investigated by measuring X-ray diffraction pattern, hysteresis curve, initial permeability and resistivity. The results showed that all of the three samples were good soft magnetic materials, and initial permeability increased with the decreasing of Hc as the sintering temperature became higher. Especially, the sample sintered at 1200℃ showed Hc of 0.217Oe and maintained the highest value of initial permeability through the whole frequency range. The loss factors of the samples showed good frequency stability from 1 ㎑ to 10 ㎒ and both the loss factor and resistivity of the ssample sintered at 1200℃ was the least.

Studies of the Rare - Earth Magnets

Jae Gui Koh,F. Pourarian,S. Simizu,S. G. Sankar 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.5

Specimens of Nd-Fe-B magnets with various compositions have been prepared and their physical properties investigated. The basic composition of Nd-Fe-B system is Nd_(15-x)Dy_xFe_(78.5)B_(6.5) with x varying between 0 and 2. Addition of Dy improves the coercivty significantly. The bulk density of the finished magnets is -7.5 g/cc. A remanence of 1.25 kG, and energy product of 42.1 MGOe have been observed with magnets containing x=1. Thermomagnetic measurements of alloys showed that the starting alloys exhibited a Curie temperature. of -330 C.

Studies of the Magnetic Properties of Ni-Zn-Cu Ferrite and its Synthesis by Using Metal Nitrate Salts

Jae Gui Koh 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.6

Ni-Zn-Cu ferrite was synthesized by decomposing the metal nitrates Ni(NO3)26H2O, Cu(NO3)23H2O, Zn(NO3)26H2O, and Fe(NO3)39H2O at 200 C for 20 hours. The ferrite powder was calcined at 400 C and pulverized for 3, 6, 9, or 12 hours in a steel ball mill. Then, it was sintered from 700 C to 1000 C in 100 C steps for 1 hour at each step. Thus, we could study the eects of the synthesis conditions on the microstructure and magnetic properties of Ni-Zn-Cu ferrite. We could chemically bond initial specimens in liquid at a low-temperature of 150 C owing to the low melting points, less than 200 C, of the metal nitrates instead of mechanical ball-mill pulverization, thus narrowing the distance between the particles a molecular one and lowering the sintering point at least by 200 C to 300 C. The initial permeability was 50 to 470, and the maximum magnetic induction and coercive force were 0.2410 T and 39.79 A/m to 95.496 A/m, respectively, which are similar to values for Ni-Zn-Cu ferrite synthesized using a conventional process.

고투자율, 저보자력을 갖는 Ni - Zn Ferrite의 개발에 관한 연구

고재귀(Jae Gui Koh) 한국자기학회 1997 韓國磁氣學會誌 Vol.7 No.1

The effects of the various raw material composition and sintered temperature on the physical properties of Ni-Zn ferrite have been investigated.<br/> They turned out to be spinel structure by X-ray diffraction and the size of grain from microscope was from 6 ㎛ to 16 ㎛.<br/> As the sintering temperature was increased from 1030 ℃ to 1070 ℃, the initial permeability and magnetic induction has increased and the both of Q factor and coercive force has decreased.<br/> The coercive force and curie temperature were almost the same at each specimen. Their values were about 0.20 Oe and 220 ℃. The frequency of specimen will used in the range from 400 ㎑ to 20 ㎒. The basic composition of Ni_(0.14)Zn_(0.64)Cu_(0.22)Fe₂O₄ (specimen B) sintered at 1050 ℃ shows the best results at magnetic induction(Br & Bm).

Mn - Zn ferrite의 성분 및 소결 온도에 따른 물리적 특성의 향상 연구

고재귀(Jae Gui Koh) 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.4

The basic composition of Mn-Zn ferrite was Mn_(0.631)Zn_(0.316)Fe_(2.053)O₄(specimen A), Mn_(0.584)Zn_(0.312)Fe_(2.104)O₄(specimen B) and Mn_(0.538)Zn_(0.308)Fe_(2.145)O₄(specimen C) with additional 0.1 ㏖% CaCO₃ and 0.04 ㏖% V₂O_5. For high permeability and acceleration of grain growth, CaCO₃ and V₂O_5. was added.<br/> The mixture of the law materials was calcinated at 950℃ for 3 hours and then milled. The compacts of toroidal type were sintered at different temperature(1250 ℃, 1300 ℃, 1350 ℃) for 2 hours in N₂ atmosphere.<br/> The effects of the various raw material composition and sintered temperature on the physical properties of Mn-Zn ferrite have been investigated.<br/> They turned out to be spinel structure by X-ray diffraction and the size of grain from SEM was from 18 ㎛ to 23㎛.<br/> As the sintering temperature was increased from 1250 ℃ to 1350 ℃, the initial permeability and magnetic induction has increased and the both of Q factor and coercive force has decreased.<br/> The coercive force and curie temperature were almost the same at each specimen. Their values were about 0.45 Oe and 200 ℃. The frequency of specimen will used in the range from 200 ㎑ to 2 ㎒. The basic composition of Mn_(0.584)Zn_(0.312)Fe_(2.104)O₄ (specimen B) sintered at 1300 ℃ shows the best results at magnetic induction (Br & Bm).

Pr - Fe - B계 희토류 자석의 물리적 특성 향상에 관한 연구

고재귀(Jae Gui Koh),임상희(Sang-Hee Lim) 한국자기학회 1996 韓國磁氣學會誌 Vol.6 No.5

To obtain the Pr-Fe-B ternary system magnets with higher (BH)max, the effect of composition ratio and various heat-treatment temperatures on the magnetic properties of Pr-Fe-B system rare-earth magnets were investigated.<br/> The magnets with various composition of Pr and Fe were heat-treated at 990 ℃, 625 ℃, 585 ℃, 550 ℃ after sintering.<br/> Curie temperature is 310 ℃ and quantitative analysis by SEM, EDX shows that the Pr₂Fe₁₄B, Pr-rich phase consist of Pr~14 at.% and Fe~86 at.%, Pr~58 at.% and Fe~42 at.%, respectively, The coercivity is decreased after heat-treating at 990 ℃ and increased from 5.6 to 6.3 kOe at 625 ℃. The maximum energy product is decreased from 43.4 to 30.3 MGOe after the heat-treating at 990 ℃ but increased from 42.7 to 45.0 MGOe, about 5 %, by heat-treating at 625℃.

ZnO가 Lithium ferrite의 물리적 특성에 미치는 영향에 관한 연구

고재귀(Jae Gui Koh) 한국자기학회 1999 韓國磁氣學會誌 Vol.9 No.5

Lithium ferrites are prominent in the element of microwave frequency communication core and high frequency memory core because of their low coercivity and the high squareness ratio. This paper reports primarily the development of lithium ferrites with the low coercivity and high squareness ratio. The materials with Li_(0.48-0.5x)Bi_(0.02)Ni_(0.04)Zn_xFe_(2.46-0.5x)O₄(x=0, 0.01, 0.02, 0.03) have been prepared to investigate the physical properties. The addition of ZnO gave raised maximun induction (Bm) and decreased coercive force (Hc), but the squareness ratio (R = Bm/Br) was decreased. The specimen of squareness ratio R=0.82, coercive force Hc=1.80 Oe was obtained for Li_(0.48-0.5x)Bi_(0.02)Ni_(0.04)Zn_xFe_(2.46-0.5x)O₄(X=0) sintered at 1050 ℃. Also the sample of squareness ratio R=0.75, coercive force Hc=1.70 Oe for Li_(0.48-0.5x)Bi_(0.02)Ni_(0.04)Zn_xFe_(2.46-0.5x)O₄(X=0) sintered at 1100 ℃ was measured. The Tc was obtained 463 ℃ and the Br of enviromental temperature variation was stable.