Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463881
A. Rao, S. B. Raju
Substitution of foreign cation in a ferrite lattice plays a vital role in enhancing its physical properties. In the past, studies on this area rarely deal with higher than tetravalent cations. The role of high valence cations (Ti, Zr, Sn, Nb, Sb, Mo) including tetravalent ions in altering physical properties (such as saturation magnetization and resistivity) of different spinel ferrite system is being investigated.
{"title":"Influence of high valence cations on soft spinel properties","authors":"A. Rao, S. B. Raju","doi":"10.1109/INTMAG.2005.1463881","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463881","url":null,"abstract":"Substitution of foreign cation in a ferrite lattice plays a vital role in enhancing its physical properties. In the past, studies on this area rarely deal with higher than tetravalent cations. The role of high valence cations (Ti, Zr, Sn, Nb, Sb, Mo) including tetravalent ions in altering physical properties (such as saturation magnetization and resistivity) of different spinel ferrite system is being investigated.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130636474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1464440
H. Sukegawa, S. Nakamura, A. Hirohata, N. Tezuka, S. Sugimoto, K. Inomata
Coulomb blockade dominates the electron transport in an ultra-small double tunnel junction. Here, a helicon sputtering deposition system is used to fabricated Co/sub 90/Fe/sub 10//AlO/sub x//Co/sub 90/Fe/sub 10//AlO/sub x//Co/sub 90/Fe/sub 10/ MDTJs. The enhancement of TMR ratio within the Coulomb blockade regime. TMR curves across the MDTJs show a superparamagnetic behavior. It was also observed that the bias voltage dependence of the TMR becomes broader above 50 K, and the enhancement of the TMR around zero bias disappears at room temperature.
{"title":"Tunnel magnetoresistance enhancement in ferromagnetic tunnel junctions with ferromagnetic nano-particle layer insertion","authors":"H. Sukegawa, S. Nakamura, A. Hirohata, N. Tezuka, S. Sugimoto, K. Inomata","doi":"10.1109/INTMAG.2005.1464440","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464440","url":null,"abstract":"Coulomb blockade dominates the electron transport in an ultra-small double tunnel junction. Here, a helicon sputtering deposition system is used to fabricated Co/sub 90/Fe/sub 10//AlO/sub x//Co/sub 90/Fe/sub 10//AlO/sub x//Co/sub 90/Fe/sub 10/ MDTJs. The enhancement of TMR ratio within the Coulomb blockade regime. TMR curves across the MDTJs show a superparamagnetic behavior. It was also observed that the bias voltage dependence of the TMR becomes broader above 50 K, and the enhancement of the TMR around zero bias disappears at room temperature.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130660784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463641
H. Tian, S. Yamada, M. Iwahara, H. Watanabe, H. Tooyama
High lift-off inspection in eddy current testing (ECT) has wide and important applications. However the reliable ECT detection for shallow scratches is generally carried out only on the surface or with a low lift-off height from probe because of the large lift-off noise of sensor and decreasing signal level in the high lift-off condition. In this paper, the proposed ECT probe is consisted of vertical rectangle exciting coil and spin-valve type giant magnetoresistive (SV-GMR) sensor to detect the surface scratches of 0.3 mm depth in a stainless steel plate with a 5 mm lift-off height. This structure of probe can suppress lift-off noise and pick up magnetic field signals up to several /spl mu/T. In addition, 3-D finite element method (FEM) is applied to simulate the length information as well as scratches information using a single GMR sensor probe scanning. Experimental results prove that the proposed ECT probe has good detection capabilities in the condition of high lift-off height.
{"title":"Eddy-current scratch inspection with high probe lift-off","authors":"H. Tian, S. Yamada, M. Iwahara, H. Watanabe, H. Tooyama","doi":"10.1109/INTMAG.2005.1463641","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463641","url":null,"abstract":"High lift-off inspection in eddy current testing (ECT) has wide and important applications. However the reliable ECT detection for shallow scratches is generally carried out only on the surface or with a low lift-off height from probe because of the large lift-off noise of sensor and decreasing signal level in the high lift-off condition. In this paper, the proposed ECT probe is consisted of vertical rectangle exciting coil and spin-valve type giant magnetoresistive (SV-GMR) sensor to detect the surface scratches of 0.3 mm depth in a stainless steel plate with a 5 mm lift-off height. This structure of probe can suppress lift-off noise and pick up magnetic field signals up to several /spl mu/T. In addition, 3-D finite element method (FEM) is applied to simulate the length information as well as scratches information using a single GMR sensor probe scanning. Experimental results prove that the proposed ECT probe has good detection capabilities in the condition of high lift-off height.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123625236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1464129
Ee-Ling Kek, Yansheng Ma, S. Sinha, Bo Liu
The load/unload (L/UL) processes of relatively high flying height (FH) sliders have been studied extensively. The pitch static attitude (PSA), roll static attitude (RSA), L/UL velocities, disk RPM, suspension limiter, and slider air-bearing surface (ABS) design are important factors that can affect the L/UL performance significantly. It is inevitable that sliders are required to fly below 5 nm with the rapid increase in areal density. At such a low FH, it is a big challenge to L/UL a slider safely. However, L/UL process and slider design strategy for a safe L/UL of ultra-low FH sliders are seldom studied so far. In this paper, the effects of vertical L/UL velocities, disk RPM, PSA and RSA gram load, slider crown/camber and mask shifting in the slider manufacturing process on the L/UL performance of a sub-5-nm FH slider are studied. Then, a design guideline for better L/UL performance is proposed and its effectiveness is verified.
{"title":"Load/unload processes for sub-5-nm flying height sliders","authors":"Ee-Ling Kek, Yansheng Ma, S. Sinha, Bo Liu","doi":"10.1109/INTMAG.2005.1464129","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464129","url":null,"abstract":"The load/unload (L/UL) processes of relatively high flying height (FH) sliders have been studied extensively. The pitch static attitude (PSA), roll static attitude (RSA), L/UL velocities, disk RPM, suspension limiter, and slider air-bearing surface (ABS) design are important factors that can affect the L/UL performance significantly. It is inevitable that sliders are required to fly below 5 nm with the rapid increase in areal density. At such a low FH, it is a big challenge to L/UL a slider safely. However, L/UL process and slider design strategy for a safe L/UL of ultra-low FH sliders are seldom studied so far. In this paper, the effects of vertical L/UL velocities, disk RPM, PSA and RSA gram load, slider crown/camber and mask shifting in the slider manufacturing process on the L/UL performance of a sub-5-nm FH slider are studied. Then, a design guideline for better L/UL performance is proposed and its effectiveness is verified.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121330784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463938
S.F. Zhao, J. Zhao, Z. Zeng, X. Han, Y. Ando, T. Miyazaki
Double barrier magnetic tunnel junction (DBMTJ) with layer structures Ta/Cu/Ni/sub 79/Fe/sub 21//Ir/sub 22/Mn/sub 78//Co/sub 75/Fe/sub 25//Al -oxide/Ni/sub 79/Fe/sub 21//Al-oxide/Co/sub 75/Fe/sub 25//Ir/sub 22/Mn/sub 78// Py/Cu/Ta are deposited on Si/SiO/sub 2/ wafer using magnetron sputtering. Tunneling magnetoresistance(TMR) ratio of 18.7% and 28.4%, resistance-area product RS of around 12.7 and 10.3 k/spl Omega//spl mu/m/sup 2/ and coercivity of 17.5 and 2.0 Oe at room temperature are obtained for the DBMTJ. Micromagnetic simulations for the dynamic domain structures under increasing DC current and the magnetic switching properties are done using the energy minimization method. The magnetocrystalline anisotropy constant K/sub 1/=1.0/spl times/10/sup 3/ erg/cm/sup 3/, spontaneous magnetization M/sub s/=800 Oe, and exchange interaction constant A=1.0/spl times/10/sup -6/ erg/cm values for the free layer are taken from the parameters of Ni/sub 79/Fe/sub 21/ alloy. The simulations show that the dynamic butterfly-shaped domains and magnetization switching can occur in the free layer when a DC current passes through the DBMTJ on the order of 100 /spl mu/A to 10 mA, under a DC bias voltage of 10-1000 mV. It decreases the magnetization in the free layer which results into the low TMR ratio observed in the DBMTJ.
{"title":"Tunneling current-induced butterfly-shaped domains and magnetization switching in double-barrier magnetic tunnel junctions","authors":"S.F. Zhao, J. Zhao, Z. Zeng, X. Han, Y. Ando, T. Miyazaki","doi":"10.1109/INTMAG.2005.1463938","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463938","url":null,"abstract":"Double barrier magnetic tunnel junction (DBMTJ) with layer structures Ta/Cu/Ni/sub 79/Fe/sub 21//Ir/sub 22/Mn/sub 78//Co/sub 75/Fe/sub 25//Al -oxide/Ni/sub 79/Fe/sub 21//Al-oxide/Co/sub 75/Fe/sub 25//Ir/sub 22/Mn/sub 78// Py/Cu/Ta are deposited on Si/SiO/sub 2/ wafer using magnetron sputtering. Tunneling magnetoresistance(TMR) ratio of 18.7% and 28.4%, resistance-area product RS of around 12.7 and 10.3 k/spl Omega//spl mu/m/sup 2/ and coercivity of 17.5 and 2.0 Oe at room temperature are obtained for the DBMTJ. Micromagnetic simulations for the dynamic domain structures under increasing DC current and the magnetic switching properties are done using the energy minimization method. The magnetocrystalline anisotropy constant K/sub 1/=1.0/spl times/10/sup 3/ erg/cm/sup 3/, spontaneous magnetization M/sub s/=800 Oe, and exchange interaction constant A=1.0/spl times/10/sup -6/ erg/cm values for the free layer are taken from the parameters of Ni/sub 79/Fe/sub 21/ alloy. The simulations show that the dynamic butterfly-shaped domains and magnetization switching can occur in the free layer when a DC current passes through the DBMTJ on the order of 100 /spl mu/A to 10 mA, under a DC bias voltage of 10-1000 mV. It decreases the magnetization in the free layer which results into the low TMR ratio observed in the DBMTJ.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114078171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463846
S. Wang, H. Fujiwara
The general features of magnetisation response of bilayer systems to an applied field is investigated to facilitate better understanding of the mechanism of the toggle-switching. Based on the detailed analysis of the response of the magnetisations of the SAF (synthetic antiferromagnet) using Stoner-Wohlfarth model, it is reported that the operating field can be substantially reduced by setting the shape anisotropy orthogonal to the intrinsic induced anisotropy, keeping the direction of the stable anti-parallel configuration parallel to the intrinsic anisotropy when no field is applied.
{"title":"Orthogonal shape/intrinsic anisotropy toggle-MRAM","authors":"S. Wang, H. Fujiwara","doi":"10.1109/INTMAG.2005.1463846","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463846","url":null,"abstract":"The general features of magnetisation response of bilayer systems to an applied field is investigated to facilitate better understanding of the mechanism of the toggle-switching. Based on the detailed analysis of the response of the magnetisations of the SAF (synthetic antiferromagnet) using Stoner-Wohlfarth model, it is reported that the operating field can be substantially reduced by setting the shape anisotropy orthogonal to the intrinsic induced anisotropy, keeping the direction of the stable anti-parallel configuration parallel to the intrinsic anisotropy when no field is applied.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"30 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114528501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1464154
Y. Sakuraba, J. Nakata, M. Oogane, H. Kubota, Y. Ando, A. Sakuma, T. Miyazaki
This paper presents an experiment performed to determine the growth condition of an ideal Co/sub 2/MnAl epitaxial films as a bottom electrode of magnetic tunnel junctions (MTJ). A high-quality epitaxial films of Heusler-type alloys Co/sub 2/MnAl was fabricated using magnetron sputtering in ultrahigh vacuum. On a single crystal MgO(001) substrate, a 40 nm-thick Cr(001) buffer layer was deposited at room temperature before it was annealed to achieve better substrate morphology. A 30 nm-thick Co/sub 2/MnAl bottom electrode was then subsequently grown at various temperatures. From X-ray diffraction (XRD) results, a perfect [001]-preferred growth from the /spl theta/-2/spl theta/ mode was confirmed and the Co/sub 2/MnAl lattice is rotated by 45/spl deg/ relative to the MgO lattice in the plane. Atomic force microprobe measured the substrate temperature dependence of surface roughness, Ra, of samples with and without Cr buffer layer. It was observed that Ra was improved using Cr buffer layer. The film deposited at room temperature was found to have the flattest surface. However, from magnetization measurement by SQUID, it showed that Co-Mn type disorder causing a reduction of spin polarization could occur in the Co/sub 2/MnAl film, which is unsuitable for an electrode of MTJ. The films were post-annealed at various temperatures and obtained a high spin-polarization in the fabricated Co/sub 2/MnAl film.
{"title":"Fabrication of Heusler-type Co/sub 2/MnAl epitaxial films by using sputtering method","authors":"Y. Sakuraba, J. Nakata, M. Oogane, H. Kubota, Y. Ando, A. Sakuma, T. Miyazaki","doi":"10.1109/INTMAG.2005.1464154","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464154","url":null,"abstract":"This paper presents an experiment performed to determine the growth condition of an ideal Co/sub 2/MnAl epitaxial films as a bottom electrode of magnetic tunnel junctions (MTJ). A high-quality epitaxial films of Heusler-type alloys Co/sub 2/MnAl was fabricated using magnetron sputtering in ultrahigh vacuum. On a single crystal MgO(001) substrate, a 40 nm-thick Cr(001) buffer layer was deposited at room temperature before it was annealed to achieve better substrate morphology. A 30 nm-thick Co/sub 2/MnAl bottom electrode was then subsequently grown at various temperatures. From X-ray diffraction (XRD) results, a perfect [001]-preferred growth from the /spl theta/-2/spl theta/ mode was confirmed and the Co/sub 2/MnAl lattice is rotated by 45/spl deg/ relative to the MgO lattice in the plane. Atomic force microprobe measured the substrate temperature dependence of surface roughness, Ra, of samples with and without Cr buffer layer. It was observed that Ra was improved using Cr buffer layer. The film deposited at room temperature was found to have the flattest surface. However, from magnetization measurement by SQUID, it showed that Co-Mn type disorder causing a reduction of spin polarization could occur in the Co/sub 2/MnAl film, which is unsuitable for an electrode of MTJ. The films were post-annealed at various temperatures and obtained a high spin-polarization in the fabricated Co/sub 2/MnAl film.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116199616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463664
T. Kim, I. Hwang, Y.K. Kim, R. Gambino, W. Park
Magnetic tunnel junctions (MTJ) with large tunnelling magnetoresistance are described. The MTJs are comprised of a half-metallic ferromagnetic Co/sub 2/MnSi (a Heusler alloy) layer, AlO/sub x/ as the insulating tunnel barrier, and a ferromagnetic layer of CoFe. The CoFe layer is pinned by exchange coupling to antiferromagnetic IrMn capped with 60 nm of Ru to prevent oxidation of the antiferromagnetic layer. The Heusler alloy with well defined smooth surface roughness was deposited by sputtering on to oxidized silicon substrates using a seed layer of Ta.
{"title":"Extraordinary tunnel magnetoresistance in half metallic ferromagnetic devices","authors":"T. Kim, I. Hwang, Y.K. Kim, R. Gambino, W. Park","doi":"10.1109/INTMAG.2005.1463664","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463664","url":null,"abstract":"Magnetic tunnel junctions (MTJ) with large tunnelling magnetoresistance are described. The MTJs are comprised of a half-metallic ferromagnetic Co/sub 2/MnSi (a Heusler alloy) layer, AlO/sub x/ as the insulating tunnel barrier, and a ferromagnetic layer of CoFe. The CoFe layer is pinned by exchange coupling to antiferromagnetic IrMn capped with 60 nm of Ru to prevent oxidation of the antiferromagnetic layer. The Heusler alloy with well defined smooth surface roughness was deposited by sputtering on to oxidized silicon substrates using a seed layer of Ta.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116334774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1464455
K. Perdue, M. Carey, P. Sparks, J. Eckert
This work uses the giant magnetoresistance (GMR) of spin valves with pico-scale IrMn layers to determine the exchange biasing effects. The samples were prepared by magnetron sputtering. This paper focuses on the results for the 5 K measurements of the GMR, exchange field and coercive field. The coercive field and exchange field are measured as a function of IrMn thickness and it was found that for IrMn layers /spl les/12 /spl Aring/, the coercive field is larger than the exchange field.
{"title":"Exchange bias and giant magnetoresistance in spin valves with pico-scale antiferromagnetic layers","authors":"K. Perdue, M. Carey, P. Sparks, J. Eckert","doi":"10.1109/INTMAG.2005.1464455","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464455","url":null,"abstract":"This work uses the giant magnetoresistance (GMR) of spin valves with pico-scale IrMn layers to determine the exchange biasing effects. The samples were prepared by magnetron sputtering. This paper focuses on the results for the 5 K measurements of the GMR, exchange field and coercive field. The coercive field and exchange field are measured as a function of IrMn thickness and it was found that for IrMn layers /spl les/12 /spl Aring/, the coercive field is larger than the exchange field.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121485441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463658
Sang Won Lee, Sam Jin Kirm, I. Shim, C. Kim
Synthesis of iron oxide nanoparticles and correct characterizations by Mossbauer spectroscopy and transmission electron microscope (TEM) are reported. Mossbauer studies are essential tool because the only X-ray diffractometer (XRD) patterns in nanoparticles could not distinguish iron oxides from magnetite, maghemite, and spinel oxides because of similar crystal structure. MFe/sub 2/O/sub 4/ (M = Fe, Co) with spinel structure are made by reaction of iron(III) acetylacetonate [Fe(acac)/sub 3/] with surfactants at high temperature. We have used the phenyl ether, benzyl ether, and 1,2-hexadecanediol as solvents. Fe(acac)/sub 3/ was mixed in phenyl ether and benzyl ether for synthesis of the magnetite (Fe/sub 3/O/sub 4/). As boiling point of phenyl ether (259 /spl deg/C) is lower than that of benzyl ether (298 /spl deg/C), the size of magnetite nanoparticles can be controlled. And then, iron oxide nanoparticles have been coated by tetraethyl orthosilicate (TEOS) mixed ethyl alcohol and NH/sub 4/OH. The average particle sizes of iron oxides were 6, 13, and 18 nm, narrow size distribution was convinced by TEM. The Mossbauer spectrum for the 6 nm sample at room temperature displays a superparamagnetic behavior as demonstrated by the single quadrupole doublet with zero hyperfine fields. While 13 and 18 nm particle show partially superparamagnetic behavior at room temperature. It is concluded that 13 nm and 18 nm samples are maghemite and magnetite, respectively, from the Mossbauer spectra. It is suggested that 6 nm samples are available for biomedical applications such as hyperthermia and drug delivery system as a magnetic fluid carrier.
{"title":"Mossbauer studies of nano-size controlled iron oxide for biomedical applications","authors":"Sang Won Lee, Sam Jin Kirm, I. Shim, C. Kim","doi":"10.1109/INTMAG.2005.1463658","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463658","url":null,"abstract":"Synthesis of iron oxide nanoparticles and correct characterizations by Mossbauer spectroscopy and transmission electron microscope (TEM) are reported. Mossbauer studies are essential tool because the only X-ray diffractometer (XRD) patterns in nanoparticles could not distinguish iron oxides from magnetite, maghemite, and spinel oxides because of similar crystal structure. MFe/sub 2/O/sub 4/ (M = Fe, Co) with spinel structure are made by reaction of iron(III) acetylacetonate [Fe(acac)/sub 3/] with surfactants at high temperature. We have used the phenyl ether, benzyl ether, and 1,2-hexadecanediol as solvents. Fe(acac)/sub 3/ was mixed in phenyl ether and benzyl ether for synthesis of the magnetite (Fe/sub 3/O/sub 4/). As boiling point of phenyl ether (259 /spl deg/C) is lower than that of benzyl ether (298 /spl deg/C), the size of magnetite nanoparticles can be controlled. And then, iron oxide nanoparticles have been coated by tetraethyl orthosilicate (TEOS) mixed ethyl alcohol and NH/sub 4/OH. The average particle sizes of iron oxides were 6, 13, and 18 nm, narrow size distribution was convinced by TEM. The Mossbauer spectrum for the 6 nm sample at room temperature displays a superparamagnetic behavior as demonstrated by the single quadrupole doublet with zero hyperfine fields. While 13 and 18 nm particle show partially superparamagnetic behavior at room temperature. It is concluded that 13 nm and 18 nm samples are maghemite and magnetite, respectively, from the Mossbauer spectra. It is suggested that 6 nm samples are available for biomedical applications such as hyperthermia and drug delivery system as a magnetic fluid carrier.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121555950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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