Improved properties of La2/3Ca1/3MnO3 thin films by addition of silver

Shreekala, R.; Rajeswari, M.; Pai, S. P.; Lofland, S. E.; Smolyaninova, Vera N.; Ghosh, K.; Ogale, S. B.; Bhagat, S. M.; Downes, M.; Greene, R. L.; Ramesh, R.; Venkatesan, T.

doi:10.1063/1.124037

Cited by 73 publications

(48 citation statements)

References 14 publications

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“…Ag composites Ag is not substituted into main LCMO lattice but remain rather as an additive in the system. (280 K) is comparable to aligned thin films [6,8,15] of LCMO, and to our knowledge is the best one yet obtained for any polycrystalline mangenites. As far fixed temperature and varying field MR is concerned its shape is changed from U type to V type.…”

mentioning

confidence: 54%

“…The former guarantees the above room temperature T MI and the later high MR. The highest TCR values yet obtained were around 20% for Ag implanted LCMO laser ablated thin films [6,8] and 50% for La 2/3 (Ca,Pb) 1/3 MnO 3 single crystals [9]. For polycrystalline LCMO or similar compounds the TCR values yet seen had always been below 10%.…”

Section: Introductionmentioning

confidence: 92%

“…In case of Ag = 0.2, 0.3 and 0.4 samples the transition is quite sharp and the obvious LCMO polycrystalline hump is not seen, further TCR is improved by nearly an order of magnitude. To our knowledge these are first LCMO:Ag polycrystalline compounds having very sharp T MI , which is generally the case for aligned LCMO films [6,8,15] or single crystals [9]. For large applications occasionally the bulk compounds in form of solid rods etc are required and hence the present LCMO:Ag composites will prove to be very useful in this direction.…”

Section: Introductionmentioning

confidence: 99%

“…In these regards there had been some trials in literature [4][5][6]. For example by increasing the amount of Mn 4+ through substitutions like RE/Ag [4,5], or increase in overall oxygen content [1,7], one could shift the T MI and T FM above/close to the room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Magneto-transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3 : Ag polycrystalline composites

Awana

Tripathi

Balamurugan

et al. 2006

Solid State Communications

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We report the synthesis, (micro)structural, magneto-transport and magnetization of polycrystalline La 2/3 Ca 1/3 MnO 3 :Ag x composites with x = 0.0, 0.1, 0.2, 0.3 and 0.4. The temperature coefficient of resistance (TCR) near ferromagnetic (FM) transition is increased significantly with addition of Ag. The FM transition temperature (T FM ) is also increased slightly with Ag addition. Magneto-transport measurements revealed that magneto-resistance MR is found to be maximum near T FM . Further the increased MR of up to 60% is seen above 300 K for higher silver added samples in an applied field of 7 Tesla. Sharp TCR is seen near T FM with highest value of up to 15 % for Ag (0.4) sample, which is an order of magnitude higher than as for present pristine sample and best value yet reported for any polycrystalline LCMO compound. Increased TCR, T FM and significant above room temperature MR of La 2/3 Ca 1/3 MnO 3 :Ag x composites is explained on the basis of improved grains size and connectivity with silver addition in the matrix. Better coupled FM domains and nearly conducting grain boundaries give rise to improved physical properties of the La 2/3 Ca 1/3 MnO 3 manganites. Ag composites Ag is not substituted into main LCMO lattice but remain rather as an additive in the system. (280 K) is comparable to aligned thin films [6,8,15] of LCMO, and to our knowledge is the best one yet obtained for any polycrystalline mangenites. As far fixed temperature and varying field MR is concerned its shape is changed from U type to V type. And is maximum at all fields up to 7 Tesla at 300 K. Infact with an increase in Ag content the low T below 300K MR% decrease and the room temperature 300 K increase. For LCMO: Ag (0.4) sample the MR of up to 60% is observed in 7 Tesla field at 300 K. Even at low fields of say 1 Tesla the MR of up to 16% is seen.The results of magnetization and magneto transport of LCMO:Ag x composites can be summarized as follows: 7 1. Ag does not substitute into host LCMO matrix in our polycrystalline LCMO:Ag x composites but improved significantly the grain morphology of the host.2. The T MI and T c remain nearly invariant with increase in x (Ag content).3. The sharpness of insulator-metal transition increases dramatically with increase in x (Ag content) and high (15%) sharp TCR is observed for Ag composites 4. Though the MR is seen in all the samples right from 300 K down to 5 K, the same is negligible at 300 K and more at lower T for pure sample and is maximum at 300 K and least at 5 K for Ag (0.4) containing compounds. DISCUSSIONNow we try to explain in broad sense the main results summarized above, as far as (1) is concerned there are some very recent reports in literature, which deals with the LCMO and LCMO/ZrO 2 [20]. In all these composites the quality of the LCMO was deteriorated. In case of LCMO:Ag there is a good probability of Ag being distributed at grain boundaries and hence providing better connectivity of grains, which is seen in Fig. 2(b). In most of other composites [16][17][18][19][20] the addi...

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mentioning

confidence: 54%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magneto-transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3 : Ag polycrystalline composites

Awana

Tripathi

Balamurugan

et al. 2006

Solid State Communications

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“…[4][5][6] However the high TCR and optimized reasonable MR, in particular at low fields is always seen at below room temperature ͑Ͻ265 K͒ only. [4][5][6][7] As mentioned before for practical use of manganites as sensors, one aspires for high TCR and MR at room temperature. Though, the working temperature could be enhanced to near room temperature in case of La 0.7 Ca 0.3−x Ba x MnO 3 , the observed values of TCR and MR are reasonably good, but could not improved a lot with silver addition.…”

Section: Introductionmentioning

confidence: 99%

Magnetotransport of La0.70Ca0.3−xSrxMnO3(Ag): A potential room temperature bolometer and magnetic sensor

Awana¹,

Tripathi²,

Kumar³

et al. 2010

Journal of Applied Physics

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Here we report the optimized magnetotransport properties of polycrystalline La 0.70 Ca 0.3−x Sr x MnO 3 and their composites with Ag. The optimization was carried out by varying the Sr and Ag contents simultaneously to achieve large temperature coefficient of resistance ͑TCR͒ as well as low field magnetoresistance ͑MR͒ at room temperature. Sharpest paramagnetic ͑PM͒-ferromagnetic ͑FM͒ and insulator-metal ͑IM͒ transition is observed in the vicinity of the room temperature ͑T C Ϸ 300 K Ϸ T IM ͒ for the composition La 0.70 Ca 0.20 Sr 0.10 MnO 3 :Ag 0.20 . Partial substitution of larger Sr 2+ ions at the Ca 2+ ions sites controls the magnitude of the FM and IM transition temperatures, while the Ag induces the desired sharpness in these transitions. For the optimized composition, maximum TCR and MR are tuned to room temperature ͑300 K͒ with the former being as high as 9% and the later being ϳ20% and ϳ30% at 5 and 10 kOe magnetic fields respectively. Such sharp single peak ͑TCRϳ 9%͒ at room temperature can be used for the bolometric and infrared detector applications. The achievement of large TCR and low field MR at T ϳ 300 K in polycrystalline samples is encouraging and we believe that further improvements can be achieved in thin films which by virtue of their low conduction noise are more suitable for device applications.

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Ag‐doped manganite nanoparticles: New materials for temperature‐controlled medical hyperthermia

Mel’nikov

Gorbenko

Markelova

et al. 2008

J Biomedical Materials Res

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The purpose of this study was to introduce newly synthesized nanomaterials as an alternative to superparamagnetic ironoxide based particles (SPIO) and thus to launch a new platform for highly controllable hyperthermia cancer therapy and imaging. The new material that forms the basis for this article is lanthanum manganite particles with silver ions inserted into the perovskite lattice: La(1-x)Ag(x)MnO(3+delta). Adjusting the silver doping level, it is possible to control the Curie temperature (T(c)) in the hyperthermia range of interest (41-44 degrees C). A new class of nanoparticles based on silver-doped manganites La(1-x)Ag(x)MnO(3+delta) is suggested. New nanoparticles are stable, and their properties were not affected by the typical ambient conditions in the living tissue. It is possible to monitor the particle uptake and retention by MRI. When these particles are placed into an alternating magnetic field, their temperature increases to the definite value near T(c) and then remains constant if the magnetic field is maintained. During the hyperthermia procedure, the temperature can be restricted, thereby preventing the necrosis of normal tissue. A new class of nanoparticles based on silver-doped manganites La(1-x)Ag(x)MnO(3+delta) was suggested. Ag-doped perovskite manganites particles clearly demonstrated the effect of adjustable Curie temperature necessary for highly controllable cellular hyperthermia. The magnetic relaxation properties of the particles are comparable with that of SPIO, and so we were able to monitor the particle movement and retention by MRI. Thus, the new material combines the MRI contrast enhancement capability with targeted hyperthermia treatment.

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Improved properties of La2/3Ca1/3MnO3 thin films by addition of silver

Cited by 73 publications

References 14 publications

Magneto-transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3 : Ag polycrystalline composites

Magneto-transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3 : Ag polycrystalline composites

Magnetotransport of La0.70Ca0.3−xSrxMnO3(Ag): A potential room temperature bolometer and magnetic sensor

Ag‐doped manganite nanoparticles: New materials for temperature‐controlled medical hyperthermia

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