Isothermal Variation Of The Entropy (Δ St) For The Compound Gd5 Ge4 Under Hydrostatic Pressure

In the present work, the isothermal variation of the entropy (Δ ST) for the compound Gd5 Ge4 was studied at different applied hydrostatic pressures (from 0 up to 0.58 GPa). In all pressure ranges, we observe the giant magnetocaloric effect. The Δ ST data for the compound Gd5 Ge4 at zero applied pressure present two peaks: the lowest temperature peak is due to irreversible processes and the highest temperature peak is due to magnetostructural transitions. Increasing the pressure, the lowest temperature peak displaces to lower temperatures and disappears. The magnitude of the other peak has a nonlinear behavior with pressure. Different protocols were used to obtain Δ ST at zero applied pressure and the results indicate that Δ ST strongly depends on the initial and final states of Gd5 Ge4 compound. We also present a T-P magnetic phase diagram built from the available magnetic data. © 2008 American Institute of Physics.1046Pecharsky, V.K., Gschneidner Jr., K.A., (1999) J. Magn. Magn. Mater., 200, p. 44. , 0304-8853 10.1016/S0304-8853(99)00397-2Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , (IOP, Bristol)Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 0031-9007 10.1103/PhysRevLett.78.4494Magen, C., Arnold, Z., Morellon, L., Skorokhod, Y., Algarabel, P.A., Ibarra, M.R., Kamarad, J., (2003) Phys. Rev. Lett., 91, p. 207202. , 0031-9007 10.1103/PhysRevLett.91.207202Levin, E.M., Gschneidner Jr., K.A., Pecharsky, V.K., (2002) Phys. Rev. B, 65, p. 214427. , 0163-1829 10.1103/PhysRevB.65.214427Levin, E.M., Pecharsky, V.K., Gschneidner Jr., K.A., Miller, G.J., (2001) Phys. Rev. B, 64, p. 235103. , 0163-1829 10.1103/PhysRevB.64.235103Tang, H., Pecharsky, V.K., Gschneidner Jr., K.A., (2004) Phys. Rev. B, 69, p. 064410. , 0163-1829 10.1103/PhysRevB.69.064410Chattopadhyay, M.K., Manekar, M.A., Pecharsky, A.O., Pecharsky, V.K., Gschneidner Jr., K.A., Moore, J., Perkins, G.K., Cohen, L.F., (2004) Phys. Rev. B, 70, p. 214421. , 0163-1829 10.1103/PhysRevB.70.214421Mudryk, Ya., Holm, A.P., Gschneidner Jr., K.A., Pecharsky, V.K., (2005) Phys. Rev. B, 72, p. 064442. , 0163-1829 10.1103/PhysRevB.72.064442Levin, E.M., Gschneidner Jr., K.A., Lograsso, T.A., Schlagel, D.L., Pecharsky, V.K., (2004) Phys. Rev. B, 69, p. 144428. , 0163-1829 10.1103/PhysRevB.69.144428Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Appl. Phys. Lett., 70, p. 3299. , 0003-6951 10.1063/1.119206Nikitin, S.A., Myalikgulyev, G., Tishin, A.M., Annaorazov, M.P., Asatryan, K.A., Tyurin, A.L., (1990) Phys. Lett. A, 148, p. 363. , 0375-9601 10.1016/0375-9601(90)90819-APecharsky, V.K., Gschneidner Jr., K.A., (1999) J. Appl. Phys., 86, p. 565. , 0021-8979 10.1063/1.370767Carvalho, A.M.G., (2006), Ph.D. thesis, UNICAMPCarvalho, A.M.G., Alves, C.S., De Campos, A., Coelho, A.A., Gama, S., Gandra, F.C.G., Von Ranke, P.J., De Oliveira, N.A., (2005) J. Appl. Phys., 97, pp. 10M320. , 0021-8979 10.1063/1.1860932Gschneidner Jr., K.A., Pecharsky, V.K., (2000) Annu. Rev. Mater. Sci., 30, p. 387. , 0084-6600 10.1146/annurev.matsci.30.1.387Carvalho, A.M.G., Alves, C.S., Colucci, C.C., Bolanho, M.A., Coelho, A.A., Gama, S., Nascimento, F.C., Cardoso, L.P., (2007) J. Alloys Compd., 432, p. 11. , 0925-8388 10.1016/j.jallcom.2006.05.121Wood, M.E., Potter, W.H., (1985) Cryogenics, 25, p. 667. , 0011-2275 10.1016/0011-2275(85)90187-0Magnus, A., Carvalho, G., Coelho, A.A., Gama, S., Von Ranke, P.J., De Oliveira, N.A., Da Silva, L.M., Gandra, F.C.G., (submitted

Theoretical Investigation On The Existence Of Inverse And Direct Magnetocaloric Effect In Perovskite Euzro 3

We report on the magnetic and magnetocaloric effect calculations in antiferromagnetic perovskite-type EuZrO 3. The theoretical investigation was carried out using a model Hamiltonian including the exchange interactions between nearest-neighbor and next-nearest-neighbor for the antiferromagnetic ideal G-type structure (the tolerance factor for EuZrO 3 is t = 0.983, which characterizes a small deformation from an ideal cubic perovskite). The molecular field approximation and Monte Carlo simulation were considered and compared. The calculated magnetic susceptibility is in good agreement with the available experimental data. For a magnetic field change from zero to 2 T a normal magnetocaloric effect was calculated and for a magnetic field change from zero to 1 T, an inverse magnetocaloric effect was predicted to occur below T = 3.6 K. © 2011 American Institute of Physics.1098Warburg, E., (1881) Ann. Phys., 13, p. 141. , 10.1002/andv249:5Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 10.1103/PhysRevLett.78.4494Von Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) J. Magn. Magn. Mater., 277, p. 78. , 10.1016/j.jmmm.2003.10.013De Oliveira, N.A., Von Ranke, P.J., (2008) Phys. Rev. B, 77, p. 214439. , 10.1103/PhysRevB.77.214439Von Ranke, P.J., De Oliveira, N.A., Plaza, E.J.R., De Sousa, V.S.R., Alho, B.P., Magnus, A., Carvalho, G., Reis, M.S., (2008) J. Appl. Phys., 104, p. 093906. , 10.1063/1.3009974Sande, P., Hueso, L.E., Miguens, D.R., Rivas, J., Rivadulla, F., Lopez-Quintela, M.A., (2001) Appl. Phys. Lett., 79, p. 2040. , 10.1063/1.1403317Yamada, H., Goto, T., (2004) Physica B, 346-347, p. 104. , 10.1016/j.physb.2004.01.029Nobrega, E.P., De Oliveira, N.A., Von Ranke, P.J., Troper, A., (2006) Phys. Rev. B, 74, p. 144429. , 10.1103/PhysRevB.74.144429Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , 1st ed. (Institute of Physics, Bristol)De Oliveira, N.A., Von Ranke, P.J., (2010) Phys. Rep., 489, p. 89. , 10.1016/j.physre2009.12.006Sasaki, S., Prewitt, C.T., Liebermann, R.C., (1983) Am. Mineral., 68, p. 1189Kuz'Min, M.D., Tishin, A.M., (1991) J. Phys. D: Appl. Phys., 24, p. 2039. , 10.1088/0022-3727/24/11/020Kimura, H., Numazawa, T., Sato, M., Ikeya, T., Fukuda, T., (1995) J. Appl. Phys., 77, p. 432. , 10.1063/1.359349Phan, M.-H., Yu, S.-C., Review of the magnetocaloric effect in manganite materials (2007) Journal of Magnetism and Magnetic Materials, 308 (2), pp. 325-340. , DOI 10.1016/j.jmmm.2006.07.025, PII S0304885306009577Zong, Y., Fujita, K., Akamatsu, H., Murai, S., Tanaka, K., (2010) J. Solid State Chem., 183, p. 168. , 10.1016/j.jssc.2009.10.014Kolodiazhnyi, T., Fujita, K., Wang, L., Zong, Y., Tanaka, K., Sakka, Y., Takayama-Muromachi, E., (2010) Appl. Phys. Lett., 96, p. 252901. , 10.1063/1.3456730Greedan, J.E., Chien, C.-L., Johnston, R.G., (1976) J. Solid State Chem., 19, p. 155. , 10.1016/0022-4596(76)90163-8Nobrega, E.P., De Oliveira, N.A., Von Ranke, P.J., Troper, A., Monte Carlo calculations of the magnetocaloric effect in Gd5(SixGe1-x)4 compounds (2005) Physical Review B - Condensed Matter and Materials Physics, 72 (13), pp. 1-7. , http://oai.aps.org/oai/?verb=ListRecords&metadataPrefix= oai_apsmeta_2&set=journal:PRB:72, DOI 10.1103/PhysRevB.72.134426, 134426Nbrega, E.P., De Oliveira, N.A., Von Ranke, P.J., Troper, A., (2008) J. Magn. Magn. Mater., 320, p. 147. , 10.1016/j.jmmm.2008.02.036Landau, D.P., Binder, K., (2000) A Guide to Monte Carlo Simulations in Statistical Physics, , (Cambridge University Press, Cambridge)Yang, H., Ohishi, Y., Kurosaki, K., Muta, H., Yamanaka, S., (2010) J. Alloys Compd., 504, p. 201. , 10.1016/j.jallcom.2010.05.088Terki, R., Bertrand, G., Aourag, H., Coddet, C., Thermal properties of Ba 1-xSr xZrO 3 compounds from microscopic theory (2008) Journal of Alloys and Compounds, 456 (1-2), pp. 508-513. , DOI 10.1016/j.jallcom.2007.02.133, PII S0925838807005397Bagayoko, D., Zhao, G.L., Fan, J.D., Wang, J.T., (1998) J. Phys. Condens. Matter, 10, p. 5645. , 10.1088/0953-8984/10/25/014Von Ranke, P.J., Mota, M.A., Grangeia, D.F., Carvalho, A.M.G., Gandra, F.C.G., Coelho, A.A., Caldas, A., Gama, S., Magnetocaloric effect in the RNi 5 (R = Pr, Nd, Gd, Tb, Dy, Ho, Er) series (2004) Physical Review B - Condensed Matter and Materials Physics, 70 (13), pp. 1344281-1344286. , DOI 10.1103/PhysRevB.70.134428, 13442

Calculation Of The Giant Magnetocaloric Effect In The Mnfep 0.45as0.55 Compound

We report the theoretical investigations on the giant magnetocaloric compound MnFeP0.45As0.55. The magnetic state equation used takes into account the magnetoelastic effect that leads the magnetic system to order under first order paramagnetic-ferromagnetic phase transition. The model parameters were determined from the magnetization data adjustment and used to calculate the magnetocaloric thermodynamic quantities. The theoretical calculations are compared with the available experimental data.709944101-094410-5Yu, B.F., Gao, Q., Zhang, B., Mang, X.Z., Chen, Z., (2003) Int. J. Refrig., 26, p. 622Gschneidner Jr., K.A., Pecharsky, V.K., (1997) Rare Earths: Science, Technology and Application III, , edited by R. C. Bautista, C. O. Bounds, T. W. Ellis, and B. T. Kilbourn The Minerals, Metals & Materials Society, WarendaleBrown, G.V., (1976) J. Appl. Phys., 47, p. 3673Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494Tegus, O., Brück, E., Buschow, K.H.J., De Boer, F.R., (2002) Nature, 415, p. 150. , LondonMorellon, L., Algarabel, P.A., Ibarra, M.R., Blasco, J., García-Landa, B., Arnold, Z., Albertini, F., (1998) Phys. Rev. B, 58, pp. R14721Rodbell, D.S., (1961) Phys. Rev. Lett., 7, p. 1Bean, C.P., Rodbell, D.S., (1961) Phys. Rev., 126, p. 104Bacmann, M., Soubeyroux, J.-L., Barrett, R., Fruchart, D., Zach, R., Niziol, S., Fruchart, R., (1983) J. Magn. Magn. Mater., 134, p. 59Brück, E., Tegus, O., Li, X.W., Deboer, F.R., Buschow, K.H.J., (2003) Physica B, 327, p. 431Tegus, O., Brück, E., Zhang, L., Dagula, Buschow, K.H.J., De Boer, F.R., (2002) Physica B, 319, p. 174Zach, R., Guillot, M., Tobola, J., (1998) J. Appl. Phys., 83, p. 7237Tegus, O., (2003) Novel Materials for Magnetic Refrigeration, , PhD thesis, Van der Waals-Zeeman Instituut, Universiteit van Amsterdam, Printer Partners Ipskamp B. V., ISBN: 9057761076, OctoberVon Ranke, P.J., Grangeia, D.F., Caldas, A., De Oliveira, N.A., (2003) J. Appl. Phys., 93, p. 4055Wada, H., Tanabe, Y., (2001) Appl. Phys. Lett., 79, p. 3302Wada, H., Morikawa, T., Taniguchi, K., Shibata, T., Yamada, Y., Akishige, Y., (2003) Physica B, 328, p. 11

The Giant Anisotropic Magnetocaloric Effect In Dyal2

We report on calculations of the anisotropic magnetocaloric effect in DyAl2 using a model Hamiltonian including crystalline electrical field effects. The anisotropic effect is produced by the rotation of a constant magnetic field from the easy to a hard magnetic direction in the crystal and is enhanced by the first order nature of the field induced spin reorientation transition. The calculated results indicate that for a field with modulus of 2 T rotating from a hard to the easy direction, the isothermal magnetic entropy (Δ Siso) and adiabatic temperature (Δ Tad) changes present peak values higher than 60% the ones observed in the usual process, in which the field direction is kept constant and the modulus of the field is varied. © 2008 American Institute of Physics.1049Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , 1st ed. (Institute of Physics, Bristol)Warburg, E., (1881) Ann. Phys. (N.Y.), 13, p. 141. , 0003-4916Brown, G.V., (1976) J. Appl. Phys., 47, p. 3673. , 0021-8979 10.1063/1.323176Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 0031-9007 10.1103/PhysRevLett.78.4494Von Ranke, P.J., De Oliveira, N.A., Mello, C., Garcia, D.C., De Souza, V.A., Magnus, A., Carvalho, G., (2006) Phys. Rev. B, 74, p. 054425. , 0163-1829 10.1103/PhysRevB.74.054425Hill, T.W., Wallace, W.E., Craig, R.S., Inuone, T.J., (1973) Solid State Chem., 8, p. 364. , 10.1016/S0022-4596(73)80036-2De Oliveira, I.G., Garcia, D.C., Von Ranke, P.J., (2007) J. Appl. Phys., 102, p. 073907. , 0021-8979 10.1063/1.2783781Lima, A.L., Tsokol, A.O., Gschneidner Jr., K.A., Pecharky, V.K., Lograsso, T.A., Schlagel, D.L., (2005) Phys. Rev. B, 72, p. 024403. , 0163-1829 10.1103/PhysRevB.72.024403Von Ranke, P.J., De Oliveira, I.G., Guimarães, A.P., Da Silva, X.A., (2000) Phys. Rev. B, 61, p. 447. , 0163-1829 10.1103/PhysRevB.61.447Von Ranke, P.J., De Oliveira, N.A., Garcia, D.C., De Sousa, V.S.R., De Souza, V.A., Magnus, A., Carvalho, G., Reis, M.S., (2007) Phys. Rev. B, 75, p. 184420. , 0163-1829 10.1103/PhysRevB.75.184420Purwins, H.G., Leson, A., (1990) Adv. Phys., 39, p. 309. , 0001-8732 10.1080/00018739000101511Von Ranke, P.J., Pecharsky, V.K., Gschneidner Jr., K.A., (1998) Phys. Rev. B, 58, p. 1211

Experimental And Theoretical Analyses Of Pr Al2 And Nd Al2 Composite For Use As An Active Magnetic Regenerator

We report the theoretical and experimental investigations on the magnetocaloric effect in the Pr Al2 and Nd Al2 compounds and a composite of these compounds for use as an active magnetic regenerator. The theoretical calculations were performed considering the crystalline electrical field anisotropy and the magnetocaloric potentials were calculated in the three main crystallographic directions. The experimental data, obtained for the polycrystalline samples, are in good agreement with the theoretical results. Also, an optimum molar fraction of the Pr Al2 and Nd Al2 composite was determined theoretically and experimentally and discussed in the framework of the optimum regeneration Ericsson cycle. © 2005 American Institute of Physics.978Brown, G.V., (1976) J. Appl. Phys., 47, p. 3673Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494Tegus, O., Bruck, E., Buschow, K.H.J., De Boer, F.R., (2002) Nature (London), 415, p. 150Wada, H., Taniguchi, K., Tanabe, Y., (2002) Mater. Trans., JIM, 43, p. 73Wada, H., Tanabe, Y., (2001) Appl. Phys. Lett., 79, p. 3302Von Ranke, P.J., Nobrega, E.P., De Oliveira, I.G., Gomes, A.M., Sarthour, R.S., (2001) Phys. Rev. B, 63, p. 184406Von Ranke, P.J., De Oliveira, N.A., Tovar Costa, M.V., Caldas, A., De Oliveira, I.G., Nobrega, E.P., (2001) J. Magn. Magn. Mater., 226, p. 990Von Ranke, P.J., Pecharsky, V.K., Gschneidner Jr., K.A., (1998) Phys. Rev. B, 58, p. 12110Von Ranke, P.J., De Oliveira, I.G., Guimarães, A.P., Da Silva, X.A., (2000) Phys. Rev. B, 61, p. 447Williams, H.J., Wernick, J.H., Nesbit, E.A., Sherwood, R.C., (1962) J. Phys. Soc. Jpn., 17, p. 91Swift, W.M., Wallace, W.E., (1968) J. Phys. Chem. Solids, 29, p. 2053Mader, K.H., Segal, E., Wallace, W.E., (1969) J. Phys. Chem. Solids, 30, p. 1Nereson, N., Olsen, C., Arnold, G., (1968) J. Appl. Phys., 39, p. 4605Nereson, N., Olsen, C., Arnold, G., (1966) J. Appl. Phys., 37, p. 4575Rossignol, M.F., (1980), University of GrenoblePurwins, H.G., Leson, A., (1990) Adv. Phys., 39, p. 309Lima, A.L., Oliveira, I.S., Gomes, A.M., Von Ranke, P.J., (2002) Phys. Rev. B, 65, p. 172411Hashimoto, T., Kuzuhara, T., Sahashi, M., Inomata, K., Tomokiyo, A., Yayama, H., (1991) J. Appl. Phys., 70, p. 1911Yan, Z., Chen, J., (1992) J. Appl. Phys., 72, p. 1Smaïli, A., Chahine, R., (1996) Adv. Cryog. Eng., 42, p. 445Dai, W., (1992) J. Appl. Phys., 71, p. 527

Influence Of Spin Reorientation On Magnetocaloric Effect In Nd Al2: A Microscopic Model

We report a theoretical investigation about the influence of the spin reorientation from easy magnetic direction 001 to the applied magnetic field direction 111 on the magnetocaloric properties of Nd Al2. This compound was fully investigated using a model Hamiltonian which includes the Zeeman-exchange interactions and the crystalline electrical field, which are responsible for the magnetic anisotropy. All theoretical results were obtained using the proper model parameters for Nd Al2, found in the literature. The existence of a minimum in magnetic entropy change below the phase transition was predicted and ascribed to the strong jump on the spin reorientation. © 2006 The American Physical Society.745Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , Institute of Physics, BristolPecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , PRLTAO 0031-9007 10.1103/PhysRevLett.78.4494Tegus, O., Brück, E., Buschow, K.H.J., De Boer, F.R., (2002) Nature, 415, p. 150. , NATUAS 0028-0836 10.1038/415150AWada, H., Tanabe, Y., (2001) Appl. Phys. Lett., 79, p. 3302. , APPLAB 0003-6951Wada, H., Morikawa, T., Taniguchi, K., Shibata, T., Yamada, Y., Akishige, Y., (2003) Physica B, 328, p. 114. , PHYBE3 0921-4526 10.1016/S0921-4526(02)01822-7Hu, F., Shen, B., Sun, J., Cheng, Z., Rao, G., Zhang, X., (2001) Appl. Phys. Lett., 78, p. 3675. , APPLAB 0003-6951Fujita, A., Fujieda, S., Hasegawa, Y., Fukamichi, K., (2003) Phys. Rev. B, 67, p. 104416. , PRBMDO 0163-1829 10.1103/PhysRevB.67.104416Brown, G.V., (1976) J. Appl. Phys., 47, p. 3673. , JAPIAU 0021-8979 10.1063/1.323176Von Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) J. Magn. Magn. Mater., 277, p. 78. , JMMMDC 0304-8853 10.1016/j.jmmm.2003.10.013Von Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) Phys. Lett. a, 320, p. 302. , PYLAAG 0375-9601 10.1016/j.physleta.2003.10.067Von Ranke, P.J., De Campos, A., Caron, L., Coelho, A.A., Gama, S., De Oliveira, N.A., (2004) Phys. Rev. B, 70, p. 094410. , PRBMDO 0163-1829 10.1103/PhysRevB.70.094410Gama, S., Coelho, A.A., De Campos, A., Carvalho, A.M., Gandra, F.C.G., Von Ranke, P., De Oliveira, N.A., (2004) Phys. Rev. Lett., 93, p. 237202. , PRLTAO 0031-9007 10.1103/PhysRevLett.93.237202Von Ranke, P.J., De Oliveira, N.A., Mello, C., Carvalho, A.M., Gama, S., (2005) Phys. Rev. B, 71, p. 054410. , PRBMDO 0163-1829 10.1103/PhysRevB.71.054410Von Ranke, P.J., Gama, S., Coelho, A.A., De Campos, A., Carvalho, A.M., Gandra, F.C.G., De Oliveira, N.A., (2006) Phys. Rev. B, 73, p. 014415. , PRBMDO 0163-1829 10.1103/PhysRevB.73.014415Von Ranke, P.J., Pecharsky, V.K., Gschneidner, K.A., Korte, B.J., (1998) Phys. Rev. B, 58, p. 14436. , PRBMDO 0163-1829 10.1103/PhysRevB.58.14436Von Ranke, P.J., Mota, M.A., Grangeia, D.F., Carvalho, A.M., Gandra, F.C.G., Coelho, A.A., Caldas, A., Gama, S., (2004) Phys. Rev. B, 70, p. 134428. , PRBMDO 0163-1829 10.1103/PhysRevB.70.134428Lima, A.L., Tsokol, A.O., Gschneidner Jr., K.A., Pecharsky, V.K., Lograsso, T.A., Schlagel, D.L., (2005) Phys. Rev. B, 72, p. 024403. , PRBMDO 0163-1829 10.1103/PhysRevB.72.024403Von Ranke, P.J., De Oliveira, I.G., Guimaraes, A.P., Da Silva, X.A., (2000) Phys. Rev. B, 61, p. 447. , PRBMDO 0163-1829 10.1103/PhysRevB.61.447Lea, K.R., Leask, M.J.M., Wolf, W.P., (1962) J. Phys. Chem. Solids, 33, p. 1381. , JPCSAW 0022-3697Stevens, K.W.H., (1952) Proc. Phys. Soc., London, Sect. a, 65, p. 209. , PPSAAM 0370-1298 10.1088/0370-1298/65/3/308Purwins, H.G., Leson, A., (1990) Adv. Phys., 39, p. 309. , ADPHAH 0001-8732 10.1080/00018739000101511Bak, P., (1974) J. Phys. C, 7, p. 4097. , JPSOAW 0022-3719 10.1088/0022-3719/7/22/014Nereson, N., Olsen, C., Arnold, G., (1996) J. Appl. Phys., 37, p. 4575. , JAPIAU 0021-8979 10.1063/1.1708083Deenadas, C., Thompson, A.W., Graig, R.S., Wallace, W.E., (1971) J. Phys. Chem. Solids, 32, p. 1843. , JPCSAW 0022-3697Inoue, T., Sankar, S.G., Graig, R.S., Wallace, W.E., Gschneidner Jr., K.A., (1997) J. Phys. Chem. Solids, 38, p. 487. , JPCSAW 0022-3697Barbara, B., Boucherle, J.X., Michelutti, B., Rossignol, M.F., (1979) Solid State Commun., 31, p. 477. , SSCOA4 0038-1098Barbara, B., Rossignol, M.F., Boucherle, J.X., (1975) Phys. Lett., 55, p. 321. , PYLAAG 0375-9601 10.1016/0375-9601(75)90489-

A Comparative Study Of The Magnetocaloric Effect In Rni2 (r=nd,gd,tb) Intermetallic Compounds

Conventional and anisotropic magnetocaloric effects were studied in cubic rare earth RNi2 (R=Nd,Gd,Tb) ferromagnetic intermetallic compounds. These three compounds are representative of small, null, and large magnetocrystalline anisotropy in the series, respectively. Magnetic measurements were performed in polycrystalline samples in order to obtain the isothermal magnetocaloric data, which were confronted with theoretical results based on mean field calculations. For the R=Tb case, we explore the crystalline electrical-field anisotropy to predict the anisotropic magnetocaloric behavior due to the rotation of an applied magnetic field of constant intensity. Our results suggest the possibility of using both conventional and anisotropic magnetic entropy changes to extend the range of temperatures for use in the magnetocaloric effect. © 2009 American Institute of Physics.1051Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 0031-9007 10.1103/PhysRevLett.78.4494Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Appl. Phys. Lett., 70, p. 3299. , 0003-6951 10.1063/1.119206Von Ranke, P.J., De Oliveira, N.A., Mello, C., Garcia, D.C., De Souza, V.A., Carvalho, A.M.G., (2006) Phys. Rev. B, 74, p. 054425. , 0163-1829 10.1103/PhysRevB.74.054425De Oliveira, I.G., Garcia, D.C., Von Ranke, P.J., (2007) J. Appl. Phys., 102, p. 073907. , 0021-8979 10.1063/1.2783781Lima, A.L., Tsokol, A.O., Gschneidner Jr., K.A., Pecharsky, V.K., Lograsso, T.A., Schlagel, D.L., (2005) Phys. Rev. B, 72, p. 024403. , 0163-1829 10.1103/PhysRevB.72.024403Von Ranke, P.J., De Oliveira, N.A., Garcia, D.C., De Souza, V.S.R., De Souza, V.A., Carvalho, A.M.G., Gama, S., Reis, M.S., (2007) Phys. Rev. B, 75, p. 184420. , 0163-1829 10.1103/PhysRevB.75.184420Carvalho, A.M.G., Campoy, J.C.P., Coelho, A.A., Plaza, E.J.R., Gama, S., Von Ranke, P.J., (2005) J. Appl. Phys., 97, p. 083905. , 0021-8979 10.1063/1.1876575Plaza, E.J.R., De Sousa, V.S.R., Alho, B.P., Von Ranke, P.J., (unpublished)Von Ranke, P.J., De Oliveira, N.A., Plaza, E.J.R., De Souza, V.S.R., Alho, B., Carvalho, A.M.G., Gama, S., Reis, M.S., (2008) J. Appl. Phys., 104, p. 093906. , 0021-8979 10.1063/1.3009974Lindbaum, A., Gratz, E., Heathman, S., (2002) Phys. Rev. B, 65, p. 134114. , 0163-1829 10.1103/PhysRevB.65.134114Purwins, H.G., Leson, A., (1990) Adv. Phys., 39, p. 309. , 0001-8732 10.1080/00018739000101511Lea, K.R., Leask, M.J.M., Wolf, W.P., (1962) J. Phys. Chem. Solids, 23, p. 1381. , 0022-3697 10.1016/0022-3697(62)90192-0Stevens, K.W.H., (1952) Proc. Phys. Soc., London, Sect. A, 65, p. 209. , 0370-1298 10.1088/0370-1298/65/3/308Von Ranke, P.J., Pecharsky, V.K., Gschneidner Jr., K.A., (1998) Phys. Rev. B, 58, p. 12110. , 0163-1829 10.1103/PhysRevB.58.12110Von Ranke, P.J., Nóbrega, E.P., De Oliveira, I.G., Gomes, A.M., Sarthour, R.S., (2001) Phys. Rev. B, 63, p. 184406. , 0163-1829 10.1103/PhysRevB.63.18440

Magnetocaloric Effect In The Rni5 (r = Pr, Nd, Gd, Tb, Dy, Ho, Er) Series

In this paper, the magnetocaloric effect in the hexagonal intermetallic compounds belonging to the RNi5 series was calculated using a Hamiltonian including the crystalline electrical field, exchange interaction, and the Zeeman effect. Experimental work was performed and the two thermodynamics quantities, namely, isothermal entropy change and adiabatic temperature change were obtained for polycrystalline samples using heat capacity measurements, and compared to the theoretical predictions.70131344281-134428-6Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494Gschneidner Jr., K.A., Pecharsky, V.K., (1997) Rare Earths: Science, Technology and Application III, , edited by R. C. Bautista, C. O. Bounds, T. W. Ellis, and B. T. Kilbourn (The Minerals, Metals and Materials Society, Warendale, PATegus, O., Bruck, E., Buschow, K.H.J., De Boer, F.R., (2002) Nature (London), 415, p. 150Wada, H., Tanabe, Y., (2001) Appl. Phys. Lett., 79, p. 20(2001) Appl. Phys. Lett., 79, p. 3302Wada, H., Morikawa, T., Taniguchi, K., Shibata, T., Yamada, Y., Akishige, Y., (2003) Physica B, 328, p. 114Von Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) J. Magn. Magn. Mater., 277, p. 78Von Ranke, P.J., De Campos, A., Caron, L., Coelho, A.A., Gama, S., De Oliveira, N.A., unpublishedVon Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) Phys. Lett. A, 320, p. 302Von Ranke, P.J., Lima, A.L., Nóbrega, E.P., Da Silva, X., Guimarães, A.P., Oliveira, I.S., (2001) Phys. Rev. B, 63, p. 024422Von Ranke, P.J., Pecharsky, V.K., Gschneidner, K.A., Korte, B.J., (1998) Phys. Rev. B, 58, p. 14436Buschow, K.H.J., Van Der Goot, A.S., (1971) Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem., 27, p. 1085Stevens, K.W.H., (1952) Proc. Phys. Soc., London, Sect. A, 65, p. 209Radwanski, R.J., Kim-Ngan, N.H., Kayzel, F.E., Franse, J.J.M., Gignoux, D., Schmitt, D., Zhang, F.Y., (1992) J. Phys.: Condens. Matter, 4, p. 8853Tishin, A.M., Magnetocaloric effect in the vicinity of phase transitions (1999) Handbook of Magnetic Materials, 12, pp. 395-524. , edited by K. H. J. Buschow (North-Holland Elsevier, Amsterdam, the Netherlands), Chap. 4Marzouk, N., Graig, R.S., Wallace, W.E., (1973) J. Phys. Chem. Solids, 34, p. 15Barthem, V.M.T.S., Gignoux, D., Schmitt, D., (1989) J. Magn. Magn. Mater., 78, p. 56Zhang, F.Y., Gignoux, D., Schmitt, D., Franse, J.J.M., Kayzel, F.E., Kim-Ngan, N.H., Radwanski, R.J., (1994) J. Magn. Magn. Mater., 130, p. 108Morellon, L., Algarabel, P.A., Ibarra, M.R., Del Moral, A., Gignoux, D., Schmitt, D., (1996) J. Magn. Magn. Mater., 153, p. 17Barthem, V.M.T.S., Gignoux, D., Nait-Saada, A., Schmitt, D., Takeuchi, A.Y., (1989) J. Magn. Magn. Mater., 80, p. 142Gignoux, D., Givord, D., Del Moral, A., (1976) Solid State Commun., 19, p. 891Andreeff, A., Valter, V., Grissmann, H., Kaun, L.P., Lipold, B., Mats, V., Franzkhaim, T., (1978) JINR Rapid Commun., 1978, pp. 14-11324Marzouk, N., Graig, R.S., Wallace, W.E., (1973) J. Phys. Chem. Solids, 34, p. 1

The Magnetic And Magnetocaloric Properties Of Gd 5ge 2si 2 Compound Under Hydrostatic Pressure

The Gd5 Ge2 Si2 compound presents a giant magnetocaloric effect with transition temperature at around 276 K and is a very good candidate for application as an active regenerator material in room temperature magnetic refrigerators. Recently it has been shown that pressure induces a colossal magnetocaloric effect in MnAs, a material that presents a giant magnetocaloric effect and a strong magnetoelastic coupling, as also happens with the Gd5 Ge2 Si2 compound. This motivated a search of the colossal effect in the Gd5 Ge2 Si2 compound. This work reports our measurements on the magnetic properties and the magnetocaloric effect of Gd5 Ge2 Si2 under hydrostatic pressures up to 9.2 kbar and as a function of temperature. Contrary to what happens with MnAs, pressure increases the Curie temperature of the compound, does not affect the saturation magnetization and decreases markedly its magnetocaloric effect. © 2005 American Institute of Physics.9710Pecharsky, V.K., Gschneidner Jr., K.A., (1977) Phys. Rev. Lett., 78, p. 4494Pecharsky, V.K., Gschneidner Jr., K.A., (2001) Adv. Mater. (Weinheim, Ger.), 13, p. 683Morellon, L., Algarabel, P.A., Ibarra, M.R., Blasco, J., García-Landa, B., Arnold, Z., Albertini, F., (1998) Phys. Rev. B, 58, p. 14721Del Moral, A., Algarabel, P.A., Arnaudas, J.I., Benito, L., Ciria, M., De La Fuente, C., García-Landa, B., De Teresa, J.M., (2002) J. Magn. Magn. Mater., 242-245, p. 788Pecharsky, A.O., Gschneidner Jr., K.A., Pecharsky, V.K., (2003) J. Magn. Magn. Mater., 267, p. 60Pecharsky, A.O., Gschneidner Jr., K.A., Pecharsky, V.K., (2003) J. Appl. Phys., 93, p. 4722Gama, S., De Campos, A., Carvalho Magnus, A.G., Coelho, A.A., Gandra, F.C.G., Von Ranke, P.J., De Oliveira, N.A., (2004) Phys. Rev. Lett., 93, p. 237202Von Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) J. Magn. Magn. Mater., 277, p. 78Pecharsky, V.K., Gschneidner Jr., K.A., (1998) Adv. Cryog. Eng., 43, p. 1729Menyuk, N., Kafalas, J.A., Dwight, K., Goodenough, J.B., (1969) Phys. Rev., 177, p. 942Morellon, L., Arnold, Z., Algarabel, P.A., Magen, C., Ibarra, M.R., Skorodhod, Y., (2004) J. Phys.: Condens. Matter, 16, p. 162