Skip to main content
SpringerLink
Log in

Advanced Ceramics and Nanocomposites of Half-metallic Ferromagnetic CrO2 for Magnetic, GMR and Optical Sensors

  • Chapter
Functional Nanostructures

Part of the book series: Nanostructure Science and Technology ((NST))

Abstract

The physical properties of metal oxides are diverse, including semiconductors or insulators (ZnO, ZrO2, TiO2), good metals (RuO2), and metal-insulator systems (VO2) in terms of the electron band structure and variation of electrical resistivity (σ) as a function of temperature (T), i.e., thermal coefficient of σ, expressed as In terms of distributing the magnetic spins (of total value S) in the metal cations via O2− anions, a metal oxide behaves to be paramagnetic (C2O3), S ≠0, or diamagnetic (YBa2Cu3O7 and other ceramic superconductors1–5) with S=06–8 Depending on the relative strength of the spin-ordering over thermal effects, a paramagnetic oxide often behaves as a ferrimagnet (γ-Fe2O3 or Fe3O4) or antiferromagnet (FeO or MnO2). Metallic CrO2, with a Curie temperature T C =390 K, is the only ferromagnet in this class. Schwarz9 used local-spin-density-approximation (LSDA) band theory to predict that the S-moment would be the full 2µB required by Hund’s rules for Cr4+ (3d2) state in CrO2. The Fermi levelE F lies in a partly filled (metallic) band for the majority (up-spin)electrons, but for minority (down) spins lies in a semiconductor like energy bandgap aqueous precursor solution of CrO3 or in general a Cr6+ -compound. In the proposed polymer precursor method, the Cr6+ cations ultimately are reduced to Cr4+ cations as soon as admixing to a polymer, whichreacts with Cr6+ to form a metal ion-polymer complex capping in part of the polymer molecules.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

Log in via an institution
eBook
USD 16.99
Price excludes VAT (USA)
  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever
Softcover Book
USD 54.99
Price excludes VAT (USA)
  • Compact, lightweight edition
  • Dispatched in 3 to 5 business days
  • Free shipping worldwide - see info
Hardcover Book
USD 54.99
Price excludes VAT (USA)
  • Durable hardcover edition
  • Dispatched in 3 to 5 business days
  • Free shipping worldwide - see info

Tax calculation will be finalised at checkout

Purchases are for personal use only

Institutional subscriptions

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. J. Jung, J. P. Franck. W. A. Miner, and M. A.-K. Mohamed. Effect of substitution of Bi, Ga. and Fe on the structure and superconducting transition of Y1Ba2Cu3O6.5+δ, Phys. Rev. B 37(13), 7510–7515(1988).

    Google Scholar 

  2. Z. Iqbal, H. Eckhardt, F. Reidinger, A. Bose, J. C. Barry, and B. L. Ramakrishna, Microstructure and properties of the ∼90-K superconductor Bi2Sr3−x CaxCu2Oδ+δ, Phys. Rev. B 38(1), 859–862 (1988).

    Google Scholar 

  3. S. Ram and K. A. Narayan, Effects of Bi(x) additives on microstructure and superconductivity in YBa2−x ,BixCu3O7−δ, Phys. Rev. B 42(13), 8627–8629 (1990).

    Google Scholar 

  4. V. P. S. Awana, A. Gupta, H. Kishan, M. Karppinen, H. Yamauchi, A. V. Naiiikar, E. Galslyan, and I. Feiner. Micro-structure and magnetization of the 80-K superconductor, TbSr2Cu2.7Mo0.3O7+δ. Physica C 415, 69–73 (2004).

    Google Scholar 

  5. A. Knizhnik, G. M. Reisner, and Y. Eckstein. Increase of TC, in the 1:2:3 superconductors YBCO and (CaxLa1−x )(LauBa1−u )2Cu3Oy after slow cooling or low temperature annealing, J. Phys. Chetn. Solids 66, 1137–1144 (2005).

    Google Scholar 

  6. E. P. Wohlfarlh, Ferromagnetic Materials (North Holland, New York, 1982).

    Google Scholar 

  7. R. S. Tebble and D. J. Craik, Magnetic Materials (Wiley-Interscience. London, 1969).

    Google Scholar 

  8. W. D. Kingery, H. K. Bowen, and D. R. Uhlmann, Introduction to Ceramics (John Wiley & Sons, New York, 1975).

    Google Scholar 

  9. K. Schwarz. CrO2 predicted as a half-metallic ferromagnet, J. Phys. F: Met. Phys. 16, L211–L215 (1986).

    Google Scholar 

  10. F. Heusler, Verh. Dtsch. Phys. Ges. 5, 219 (1903).

    Google Scholar 

  11. R. A. de Groot, F. M. Mueller. P. G. van Engen, and K. H. J. Buschow. New class of materials: half-metallic ferromagnets, Phys. Rev. Lett. 50(25), 2024–2027 (1983).

    Google Scholar 

  12. K. H. J. Buschow, Handbook of Magnetic Materials (North-Holland, Amsterdam, 1991).

    Google Scholar 

  13. H. Munekala, H. Ohno, S. von Molnar, A. Segmüller, L. L. Chang, and L. Esaki, Diluted magnetic III–V semiconductors, Phys. Rev. Lett. 63(17), 1849–1852 (1989).

    Google Scholar 

  14. H. Munekala, T. Penny, and L. L. Chang, Diluted magnetic III–V semiconductor structures. Surf. Sci. 267(1–3), 342–348 (1992).

    Google Scholar 

  15. H. Ohno, A. Shen, F. Matsukura, A. Oiwa, A. Endo, S. Katsumoto, and Y. Iye, (Ga,Mn)As: A new dilutedmagneticsemiconductor based onGaAs, Appl. Phys.Lett. 69(3), 363–365 (1996).

    Google Scholar 

  16. A. Oiwa, S. Katsumoto, A. Endo, M. Hirasawa, Y. Iye, H. Ohno, P. Matsukura, A. Shen, and Y. Sugawara, Nonmetal-metal-nonmetal transition and large negative magnetoresistance in (Ga, Mn)As/GaAs, Solid State Commun. 103(4), 209–213 (1997).

    Google Scholar 

  17. S. Koshihara, A. Oiwa, M. Hirasawa. S. Katsumoto, Y. Iye, C. Urano, H. Takagi. and H. Munekata. Ferromagnetic order induced by photogenerated carriers in magnetic III–V semiconductor heteroslructures of (In,Mn)As/GaSb. Phys. Rev. Lett. 78(24), 4617–4620 (1997).

    Google Scholar 

  18. J. P. Bucher, D. C. Douglass, and L. A. Bloomfield, Magnetic properties of free cobalt clusters. Phys. Rev. Lett. 66(23), 3052–3055 (1991).

    Google Scholar 

  19. A. J. Cox, J. G. Louderback, and L. A. Bloomfield, Experimental observation of magnetism in rhodium clusters, Phys. Rev. Lett. 71(6), 923–926 (1993).

    Google Scholar 

  20. S. E. Ampsel, J. W. Emmen. J. Deng, and L. A. Bloomfield, Surface-enhanced magnetism in nickel clusters, Phys. Rev. Lett. 76(9), 1441–1444 (1996).

    Google Scholar 

  21. S. Ram and H. J-Fecht, Millimeter sized ferromagnetic Fe-clusters: formation by mechanical attrition, microstructure and magnetic properties, Mater. Trans.. JIM. 41(7), 754–760 (2000).

    Google Scholar 

  22. S. Ram, Surface structure and surface-spin induced magnetic properties and spin-glass transition in nanometer Co-granules of fcc crystal structure, J. Mater. Sci. 35, 3561–3571 (2000).

    Google Scholar 

  23. S. Ram. Allotropic phase transformations in hcp, fcc and bcc metastable structures in conanoparticles, Mater. Sci. & Eng. A 304–06, 923–927 (2001).

    Google Scholar 

  24. S. Ram and G. P Johari. Glass-liquid transition in hyperquenched metal alloys. Phil. Mag. B 61, 299–310 (1990).

    Google Scholar 

  25. S. Ram, Calorimetric investigation of structural relaxation in supercooled Ni75Al22Zr2B amorphous alloy, Phys. Rev. B 42(15), 9582–9586 (1990).

    Google Scholar 

  26. S. Ram and J. C. Joubert. Crystallization of small and separated magnetic particles of Nd2Fe14B alloy, J.Appl. Phys. 72, 1164–1171 (1992).

    Google Scholar 

  27. S. Ram and J. C. Joubert, Production of substantially stable Nd-Fe-B hydride (magnetic) powders using chemicaldissociation of water. Appl. Phys. Lett. 61(5), 613–615 (1992).

    Google Scholar 

  28. R S. Frankwicz, S. Ram, and H. J. Fecht, Enhanced microhardness in Zr65.0Al7.5Ni10.0Cu17.5 amorphous rods on coprecipitation of nanocrystallites through supersaturated intermediate solid phase particles. Appl. Phys. Lett. 68(20), 2825–2827 (1996).

    Google Scholar 

  29. S. Ram and P. S. Frankwicz. Granular GMR sensors of Co-Cu and Co-Ag nanoparticles synthesized through a chemical routeusing NaBH4, Phys. Stat. Sol. (a) 188(3), 1129–1140 (2001).

    Google Scholar 

  30. G. Kumar, J. Eckert, S. Roth, W. looser. S. Ram. and L. Schultz, Magnetic properties of Nd-Fe-Co(Cu)-Al-B amorphous alloys prepared by nonequilibrium techniques. J. Appl. Phys. 91, 3764–3768 (2002).

    Google Scholar 

  31. M. Sagawa, S. Hirosawa, H. Yamamoto. S. Fujimura, and Y. Matsuura. Nd-Fe-B permanent magnet materials, Jpn. J. Appl,Phys. 26(6), 785–800 (1987).

    Google Scholar 

  32. E. Claude, S. Ram, I. Gimenez, P. Chaudouet. D. Boursier, and J. C. Joubert, Evidence of a quantitative relationship between the degree of hydrogen intercalation and the coercivity of the two permanent magnet alloys Nd2Fe14B and Nd2Fe11Co3B, IEEE. Trans. Magn. 29, 2767–2769 (1993).

    Google Scholar 

  33. S. Ram, Kinetics of the desorption of interstitial hydrogen in stable Nd2Fe14BHx, x≤5, Phys. Rev. B 49(14), 9632–9638 (1994).

    Google Scholar 

  34. S. Ram, E. Claude, and J. C. Joubert, Synthesis, stability against air and moisture corrosion, and magnetic properties of finely divided loose Nd2Fe14BHx, x≤5, hydride powders. IEEE. Trans. Magn. 31, 2200–2208 (1995).

    Google Scholar 

  35. S. Ram, M. Febri, H. J. Fechl, and J. C. Joubert. Synthesis of Nd2Fe14B nanocrystals using interstitial hydrides, Nanostruct. Mater. 6, 473–476 (1995).

    Google Scholar 

  36. S. Haldar, S. Ram, P. Ramachandrarao, and H.D. Banerjee, Synthesis of high-energy-density Pr2Fe14−x CoxB, x≤3, magnets for practical applications, Bull. Mater. Sci. 18, 963–974 (1995).

    Google Scholar 

  37. S. Ram. Synthesis, magnetic properties, and formalism of magnetic properties of high-quality refined Nd2Fe14B powders for permanent magnet devices, J. Mater. Sci. 32, 4133–4148 (1997).

    Google Scholar 

  38. S. Ram, H.-J. Fecht, S. Haldar. P. Ramachandrarao, and H.D. Banerjee, Calorimetric study of the desorption of the interstitial hydrogenatoms in ferromagnetic Nd2Fe14BHx (x≤5) microcrystals, Phys. Rev. B 56(2), 726–737 (1997).

    Google Scholar 

  39. S. Ram, H. D. Banerjee. S. Haldar, and P. Ramachandrarao, Formation of Nd2Fe14BHx, x≤5, hydride by milling of anhydride particles in toluene in a closed reactor. Bull. Mater. Sci. 20, 1049–1058 (1997).

    Google Scholar 

  40. J. L. Tsai, T. S. Chin, and S. K. Chen, Coercivity mechanism and microstructure study of sputtered Nd-Fe-B/X/Si(III) (X=W, Pt) films, Jpn. J. Appl. Phys. 38(10), 5879–5884 (1999).

    Google Scholar 

  41. H. Brändie, D. Weiler, S. S. P. Parkin, J. C. Scott, P. Fumagalli, W. Reim, R. J. Gambino, R. Ruf, and G. Güntherodt, Magneto-optical properties of CrO2, Phys. Rev. B 46(21), 13889–13895 (1992).

    Google Scholar 

  42. S. P. Lewis, P. B. Allen, and T. Sasaki. Band structure and transport properties of CrO2, Phys. Rev. B 55(16), 10253–10260 (1997).

    Google Scholar 

  43. I.I. Mazin, Robust half metallicity in FexCo1−x S2, Appl.Phys.Lett. 77(19), 3000–3002 (2000).

    Google Scholar 

  44. R. Yamamoto, A. Machida. Y. Moritomo, and A. Nakamura. Electronic structure of half-metallic materials: comparison of pyrite with doped manganite. Physica B 281–282, 705–706 (2000).

    Google Scholar 

  45. I. S. Elfimov. S. Yunoki, and G. A. Sawatzky, Possible path to a new class of ferromagnetic and half-metallic ferromagneticmaterials, Phys. Rev. Lett. 89(21), 216403 (2002).

    Google Scholar 

  46. I. Galanakis, P. H. Dederichs, and N. Papanikolaou, Slater-Pauling behavior and origin of the half-metallicity of the full-Heusler alloys, Phys. Rev. B 66, 174429 (2002).

    Google Scholar 

  47. C. M. Fang, G. A. de Wijs, and R. A. de Groot, Spin-polarization in half-metals, J.Appl. Phys. 91(10), 8340–8344 (2002).

    Google Scholar 

  48. J. M. D. Coey and M. Venkatesan. Half-metallic ferromagnctism: example of CrO2, J. Appl. Phys. 91(10), 8345–8350 (2002).

    Google Scholar 

  49. Z. Szotek, W. M. Temmerman. A. S Vane. L. Petit, and H. Winter. Electronic structure of half-metallic double perovskites, Phys. Rev. B 68, 104411 (2003).

    Google Scholar 

  50. M. Zhang, X. Dai, H. Hu, G. Liu, Y. Cui, Z. Liu, J. Chen, J. Wang, and G. Wu, Search for new half-metallic ferromagneis in semi-Heusler alloys NiCrM (M=P. As, Sb, S. Se and Te), J. Phys.: Contiens. Matter 15, 7891–7899 (2003).

    Google Scholar 

  51. B. Nadgorny, I. I. Mazin, M. Osofsky, R. J. Soulen. P. Broussard, R. M. Stroud, D. J. Singh. V. G. Harris. A. Arsenov, and Y. Mukovskii. Origin of high transport spin polarization in La0.7Sr0.3MnO3: direct evidence for minority spin states. Phys.Rev. B 63, 184433 (2001).

    Google Scholar 

  52. S. Picozzi, A. Continenza, and A. J. Freeman, Co2MnX (X=Si, Ge, Sn) Heusler compounds: an ab initio study of their structural,electronic, and magnetic properties at zero and elevated pressure, Phys. Rev. B 66, 094421 (2002).

    Google Scholar 

  53. R. Vidya, P. Ravindran, A. Kjekshus, and H. Fjellvåg, Huge magneto-optical effects in half-metallic double perovskites, Phys. Rev. B 70, 184414 (2004).

    Google Scholar 

  54. Y. Sakuraba, J. Nakata, M. Oogane, Y. Ando, H. Kalo, A. Sakuma, T. Miyazaki, and H. Kubota, Magnetic tunnel junctions using B2-ordcred Co2MnAI Heusler alloy epitaxial electrode. Appl. Phys. Lett. 88, 022503 (2006).

    Google Scholar 

  55. H. Y. Hwang, S.-W. Cheong, N. P. Ong, and B. Batlogg. Spin-polarized intergrain tunneling in La2/3Sr1/3MnO3, Phys. Rev. Lett. 77(10), 2041–2044 (1996).

    Google Scholar 

  56. P. Bach, A. S. Bader, C. Rüster, C. Gould, C. R. Becker, G. Schmidt. L. W. Molenkamp, W. Weigand, C. Kumpf, E. Umbach, R. Urban, G. Wollersdorf, and B. Heinrich, Molecuiar-beam epitaxy of the half-Heusler alloy NtMnSb on (In,Ga)As/InP (001), Appl. Phys. Lett. 83(3), 521–523 (2003).

    Google Scholar 

  57. Y. S. Dedkov. U. Rüdiger, and G. Gunlherodt, Evidence for (he half-metallic ferromagnetic state of Fe3O4 by spin-resolved photoelectron spectroscopy. Phys. Rev. B 65(6), 064417 (2002).

    Google Scholar 

  58. Z. Szotek, W. M. Temmernian, A. Svane, L. Petit, G. M. Slocks, and H. Winter. Ah initio study of charge order in Fe3O4, Phys. Rev. B 68, 054415 (2003).

    Google Scholar 

  59. J. S. Parker, P. G. Ivanov, D. M. Lind, P. Xiong. and Y. Xin, Large inverse magnetoresistance of CrO2/Co junctions with an artificial barrier, Phys. Rev. B 69, 220413 (2004).

    Google Scholar 

  60. L. Wang, K. Umemolo, R. M. Wentzcovitch, T. Y Chen, C. L. Chien. J. G. Checkelsky. J. C. Eckeil. E. D. Dahlberg, and C. Ixighton. Co1−x FexS2: a tunable source of highly spin-polarized electrons, Phys. Rev. Lett. 94, 056602 (2005).

    Google Scholar 

  61. G. Banach, R. Tyer. and W. M. Temmerman, Study of half-metallicily in LSMO, J. Magn. & Magn. Mater. 272–276, 1963–1964 (2004).

    Google Scholar 

  62. K.-I. Kobayashi, T. Kimura, H. Sawada, K. Terakura, and Y. Tokura. Room-temperature magnetoresistance in an oxide materialwith an ordered double-perovskite structure. Nature 395, 677–680 (1998).

    Google Scholar 

  63. R. Weht, and W. E. Pickett, Half-metallic ferrimagnetism in Mn2 VA1, Phys. Rev. B 60(18), 13006–13010 (1999).

    Google Scholar 

  64. D. J. Singh. Magnetoelectronic effects in pyrochlore TI2Mn2O7: role of TI-O covalency, Phys. Rev. B 55(1), 313–316 (1997).

    Google Scholar 

  65. H. Y Hwang, and S.-W. Cheong, Low-field magnetoresistance in the pyrochlore TI2Mn2O7, Nature 389, 942–944 (1997).

    Google Scholar 

  66. P. Mavropoulos, I. Galanakis, and P. H. Dederichs. Multilayers of zinc-blende half-metals with semiconductors, J. Phys.: Condens. Matter 16, 4261–4272 (2004).

    Google Scholar 

  67. M. R. Castell, P. L. Wincott, N. G. Condon, C. Muggelberg. G. Thornton, S. L. Dudarev, A. P. Sutton, and G. A. D. Briggs, Atomic-resolution STM of a system with strongly correlated electrons: NiO (001) surface structure and defect sites, Phys. Rev. B 55(12), 7859–7863 (1997).

    Google Scholar 

  68. H. Akai, Ferromagnetismand its stability in the diluted magnetic semiconductor (In. Mn)As, Phys. Rev. Lett. 81(14), 3002–3005 (1998).

    Google Scholar 

  69. N. A. Hill, Why are there so few magnetic ferroelectrics?, J. Phys. Chem. B 104(29), 6694–6709 (2000).

    Google Scholar 

  70. M.M. Kumar, A. Srinivas, and S. V. Suryanarayana. Structure property relations in BiFeO3/BaTiO3 solid solutions, J. Appl Phys. 87(2), 855–862 (2000).

    Google Scholar 

  71. J. Y. Son. B. G. Kim, C. H. Kim, and J. H. Cho. Writing polarization bits on the multiferroic BiMnO3 thin film using Kelvin probe force microscope. Appl. Phys. Lett. 84(24), 4971–4973 (2004).

    Google Scholar 

  72. J. Zhai. N. Cai, Z. Shi, Y. Lin, and C. W. Nan, Coupled magnetodielectric properties of laminated PbZr0.53Ti0.47O3/NiFe2O4 ceramics, J.Appl. Phys. 95(10), 5685–5690 (2004).

    Google Scholar 

  73. S. B. Majumder, S. Bhattacharyya, R. S. Katiyar, A. Manivannan, P. Dutta, and M. S. Seehra, Dielectric and magnetic properties of sol-gel-derived lead iron niobate ceramics, J. Appl.Phys. 99, 024108 (2006).

    Google Scholar 

  74. C. Tien, E. V. Charnaya, V. M. Gropyanov, I. S. Miknailova, C. S. Wur. and A. A. Abramovich, Magnetic properties of a cermet on the base of Al2O3. J. Magn.& Magn. Mater. 220, 147–151 (2000).

    Google Scholar 

  75. S. Ram, D. Ghosh, and S. K Roy, Microstructure and topological analysis of Co:Al3O3 nanocermets in new FCC and BCC metastable Co-structures, J. Mater. Sci. 36, 3745–3753 (2001).

    Google Scholar 

  76. S. Ram. Self-confined dimension of thermodynamic stability in Co-nanoparticles in fcc and bcc allotrope structures with a thin amorphous Al2O3 surface layer. Acta Mater. 49, 2297–2307 (2001).

    Google Scholar 

  77. S. Rana, S. Ram, S. Seal, and S. K. Roy, Surface structure and topology in surface stabilized Co-nanoparticles with a thin Al2O3 amorphous layer. Appl. Surface Sci. 236, 141–154 (2004).

    Google Scholar 

  78. S. Rana, and S. Ram, X-ray diffraction and x-ray photoelectron spectroscopy studies of stabilized cobalt nanoparticles with a thin Al2O3 surface layer, Mater. Sci. & Tech. 21(2), 243–249 (2005).

    Google Scholar 

  79. S. Biswas, and S. Ram. (a) Morphology and stability in a half-metallic ferromagneticCrO2 compound of nanoparticles synthesized via a polymer precursor, Chem. Phys. 306, 163–169 (2004) and (b) Synthesis of shape-controlled ferromagnetic CrO2 nanoparticles by reaction in micelles of Cr6+-PVA polymer chelates. Mater. Chem. Phys. (in press).

    Google Scholar 

  80. J. H. Kim, H. Kim. D. Kim, Y. E. Ihm, and W. K. Choo, tMagnetoresistance in laser-deposited Zn1−x CoxO thin films, Physica B 327, 304–306 (2003).

    Google Scholar 

  81. S.-J. Han, B. Y. Lee, J.-S. Ku, Y. B. Kim. and Y. H. Jeong. Magnetic properties of Zn1−x CoxO, Magn. & Magn. Mater. 272–276, 2008–2009 (2004).

    Google Scholar 

  82. A. Dinia, G. Schmerber. V. Pierron-Bohnes. C. Meny, P. Panissod, and E. Beaurepaire. Magnetic perpendicular anisotropy in sputtered (Zn0.75Co0.25)O dilute magnetic semiconductor. J. Magn. & Magn. Mener. 286. 37–40 (2005).

    Google Scholar 

  83. H.-J. Lee, S. H. Choi, C. R. Cho, H. K. Kim, and S.-Y. Jeong, tThe formation of precipitates in the ZnCoO system, Europhys. Lett. 72(1), 76–82 (2005).

    Google Scholar 

  84. H. Ndilimabaka, S. Colis. G. Schmerber, D. Muller, J. J. Grob, L. Gravier, C. Jan, E. Beaurepaire, and A. Dinia, tAs-doping effect on magnetic, optical and transport properties of Zn0.9Co0.1O diluted magnetic semiconductor, Chem. Phys. Lett. 421. 184–188 (2006).

    Google Scholar 

  85. D. Rodic, V. Spasojevic, A. Bajorek, and P. Onnerud. Similarity of structure properties of Hg1−x Mnx S and Cd1−x Mnx S (structure properties of HgMnS and CdMnS), J. Magn. & Magn. Mater. 152, 159–164 (1996).

    Google Scholar 

  86. D.-S. Chuu, Y.-C. Chang, and C.-Y. Hsieh, Growth of CdMnS films by pulsed laser evaporation, Thin Solid Films 304, 28–35 (1997).

    Google Scholar 

  87. L. Levy. D. Ingert. N. Feltin. and M. P. Pileni, Cd1−yMnyS nanoparticles: absorption and photoluminescence properties, J. Crystal Growth 184/185, 377–382 (1998).

    Google Scholar 

  88. Q. Pang, B. C. Guo, C. L. Yang, S. H. Yang, M. L. Gong, W. K. Ge, and J. N. Wang, Cd1−x MnxS quantum dots: new synthesis and characterization, J. Crystal Growth 269, 213–217 (2004).

    Google Scholar 

  89. J. P. Woods, B. M. Patterson, A. S. Fernando, S. S. Jaswal, D. Welipitiya, and D. J. Sellmyer, Electronic structures and Curie temperatures of iron-based rare-earth permanent-magnet compounds, Phys. Rev. B 51(2), 1064–1072 (1995).

    Google Scholar 

  90. J. M. D. Coey, Interstitial interme tallics, J. Magn. & Magn. Mater. 159, 80–89 (1996).

    Google Scholar 

  91. J. M. D. Coey and P. A. I. Smith. Magnetic nitrides, J. Magn. & Magn. Mater. 200, 405–424 (1999).

    Google Scholar 

  92. R. Q. Wu, G. W. Peng, L. Liu, and Y. P. Feng. Possible graphitic-boron-nilride-based metal-free molecular magnets from first principles study, J. Phys.: Condens. Matter 18, 569–575 (2006).

    Google Scholar 

  93. H. Eschrig and W. E. Pickett, Density functional theory of magnetic systems revisited, Solid State Commun. 118, 123–127 (2001).

    Google Scholar 

  94. K. P. Kämper, W. Schmitt, G. Güntherodt, R. J. Gambino, and R. Ruf. CrO2—a new half-metallic ferromagnet?, Phys. Rev. Lett. 59(24), 2788–2791 (1987).

    Google Scholar 

  95. H. Y. Hwang and S.-W. Chcong. Enhanced intergrain tunneling magnetoresistance in half-metallic CrO2 films, Science 278(5343), 1607–1609 (1997).

    Google Scholar 

  96. M. A. Korotin, V. I. Anisimov, D. I. Khomskii, and G. A. Sawatzky, CrO2: a self-doped double exchange ferromagnet, Phys. Rev. Lett. 80(19), 4305–4308 (1998).

    Google Scholar 

  97. M. Rabe, J. Dreßen, D. Dahmen, J. Pommer, H. Stahl, U. R üdiger, G. Güntherodt, S. Senz, and D. Hesse, Preparation and characterization of thin ferromagnetic CrO2 films for applications in magnetoelectronics, J. Magn. & Magn. Mater. 211, 314–319 (2000).

    Google Scholar 

  98. A. Gupta, X. W. Li, and G. Xiao, Magnetic and transport properties of epitaxial and polycrystalline chromium dioxide thin films, J. Appl. Phys. 87(9), 6073–6078 (2000).

    Google Scholar 

  99. A. Barry, J. M. D. Coey, and M. Viret, A CrO2-based magnetic tunnel junction, J. Phys.: Condens. Matter. 12, L173–L175 (2000).

    Google Scholar 

  100. J. Dai and J. Tang, Junction-like magnetoresistance of intergranular tunneling in field-aligned chromium dioxide powders, Phys. Rev. B 63, 054434 (2001).

    Google Scholar 

  101. W. F. McClume. JCPDS X-ray powder diffraction file 9–332, Joint Committee on powder diffraction standards (International Center for Diffraction Data, Swarthmore, PA USA, 1979).

    Google Scholar 

  102. J. Dai, J. Tang, H. Xu, L. Spimi, W. Wang, K. Wang, A. Kumbhar, M. Li. and U. Diebold, Characterization of the natural barriers of intergranular tunnel junctions: Cr2O3 surface layers on CrO2 nanoparticles, Appl. Phys. Lett. 77(18), 2840–2842 (2000).

    Google Scholar 

  103. R. Cheng. B. Xu, C. N. Borca, A. Sokolov, C.-S. Yang, L. Yuan, S.-H. Liou, B. Doudin, and P. A. Dowben. Characterization of the native Cr2O3 oxide surface of CrO2, Appl. Phys. Lett. 79(19), 3122–3124 (2001).

    Google Scholar 

  104. H. Gleiter, Nanocrystalline materials, Prog. Mater. Sci. 33(4), 223–315 (1989).

    Google Scholar 

  105. R. W. Siegel, Cluster-assembled nanophase materials, Annu. Rev. Mater. Sci. 21, 559–578 (1991).

    Google Scholar 

  106. B. Kubota, Decomposition of higher oxides of chromium under various pressures of oxygen, J. Am. Ceram. Soc. 44(5), 239–248 (1961).

    Google Scholar 

  107. L. Ranno, A. Barry, and J. M. D. Coey. Production and magnetotransport properties of CrO2 films, J. Appl. Phys. 81(8), 5774–5776 (1997).

    Google Scholar 

  108. M. A. K. L. Dissanayake and L. L. Chase, MoO2, and WO2 in the range 0.2–6 eV, Phys. Rev. B 18(12), 6872–6879 (1978).

    Google Scholar 

  109. J. Dai and J. Tang, Temperature dependence of the conductance and magnetoresistance of CrO2 powder compacts, Phys. Rev. B 63, 064410 (2001).

    Google Scholar 

  110. S. Ishibashi, T. Namikawa, and M. Satou, (a) Epitaxial growth of CrO2 on sapphire in air, Jpn. J. Appl. Phys. 17(1), 249–250 (1978) and (b) Epitaxial growth of ferromagnetic CrO2 films in air, Mater. Res. Bull. 14(1), 51–57 (1979).

    Google Scholar 

  111. J.J. Liang, S. F. Lee, Y. D. Yao, C. C. Wu, S. G. Shyu, and C. Yu, Magnetotransport study of granular chromium dioxide thin films prepared by the chemical vapor deposition technique, J. Magn. & Magn. Mater. 239, 213–216 (2002).

    Google Scholar 

  112. W. J. DeSisto, P. R. Broussard, T. F. Ambrose, B. E. Nadgomy, and M. S. Osofsky. Highly spinpolarized chromium dioxide thin films prepared by chemical vapor deposition from chromyl chloride, Appl. Phys. Lett. 76(25), 3789–3791 (2000).

    Google Scholar 

  113. A. Anguelouch, A. Gupta, G. Xiao, D. W. Abraham, Y. Ji, S. Ingvarsson, and C. L. Chien, Nearcomplete spin polarization in atomically smooth chromium-dioxide epitaxial films prepared using a CVD liquid precursor, Phys. Rev. B 64, 180408 (2001).

    Google Scholar 

  114. P.G. Ivanov, S. M. Watts, and D. M. Lind, Epitaxial growth of CrO2 thin films by chemical-vapor deposition from a Cr8O21 precursor, J. Appl. Phys. 89(2), 1035–1040 (2001).

    Google Scholar 

  115. P. A. Dowben, Y. G. Kim, S. Baral-Tosh, G. O. Ramseyer, C. Hwang, and M. Onellion, Fabrication of ferromagnetic and antiferromagnetic chromium oxides by organometallic chemical vapor deposition, J. Appl. Phys. 67(9). 5658–5660 (1990).

    Google Scholar 

  116. R. C. DeVries, Epitaxial growth of CrO2, Mater. Res. Bull. 1(2), 83–93 (1966).

    Google Scholar 

  117. A. Bajpai and A. K. Nigam, Synthesis of high-purity samples of CrO2 by a simple route, Appl. Phys. Lett. 87, 222502 (2005).

    Google Scholar 

  118. Y. J. Chen, X. Y. Zhang, and Z. Y. Li. Enhanced room-temperature magnetoresistance in half-metallic CrO2/polymer composites, Chem. Phys. Lett. 375, 213–218 (2003).

    Google Scholar 

  119. Y. J. Chen, X. Y. Zhang, T. Y. Cai, and Z. Y. Li, Temperature dependence of ac response in diluted half-metallic CrO2 powder compact, J. Alloy. Compd. 379, 240–246 (2004).

    Google Scholar 

  120. T. J. Swoboda, P. Arthur, N. L. Cox, J. N. Ingraham, A. L. Oppegard, and M. S. Sadler, Synthesis and properties of ferromagnetic chromium oxide, J. Appl. Phys. 32(3), S374–S375 (1961).

    Google Scholar 

  121. B. L. Chamberland. (a) Crystal growth of CrO2, Mater. Res. Bull. 2(9), 827–835 (1967) and (b) The chemical and physical properties of chromium (IV) oxide and tetravalent chromium oxide derivatives, Crit. Rev. Solid State Mater. Sci. 7(1), 1–31 (1977).

    Google Scholar 

  122. T. S. Kannan and A. Jaleel, Indian Patent No. 627/Del/87 (1987).

    Google Scholar 

  123. R. A. McCurrie, Ferromagnetic Materials: Structure & Properties (Academic Press. New York, 1994).

    Google Scholar 

  124. K. Ramesha and J. Gopalakrishnan, A new method for the synthesis of chromium (IV) oxide at ambient pressure, Chem. Commun. 1173–1174 (1999).

    Google Scholar 

  125. N. L. Cox, US Patent 3 278 263 (1966).

    Google Scholar 

  126. M. Essig, M. W. Müller, and E. Schwab, Structural analysis of the stabilization layer of chromium dioxide particles, IEEE Trans. Magn. 26(1), 69–71 (1990).

    Google Scholar 

  127. T. Yu, Z. X. Shen, J. He, W. X. Sun, S. H. Tang, and J. Y. Lin, Phase control of chromium oxide in selective microregions by laser annealing, J. Appl. Phys. 93(7), 3951–3953 (2003).

    Google Scholar 

  128. E. Gaffel, M. Abdellaoui, and N. Malhouroux-Gaffet, Formation of nanosfruclural materials induced by mechanical processings (Overview), Mater. Trans., JIM, 36(2), 198–209 (1995).

    Google Scholar 

  129. J. Y. Huang, Y. K. Yu, and H. Q. Ye, Allotropic transformation of cobalt induced by ball milling, Acta mater. 44(3), 1201–1209 (1996).

    Google Scholar 

  130. V. R. Palkar, P. Ayyub, S. Chattopadhyay, and M. Multani, Size-induced structural transitions in the Cu-O and Ce-O systems, Phys. Rev B 53(5), 2167–2170 (1996).

    Google Scholar 

  131. B. S. Murly and S. Ranganalhan, Novel materials synthesis by mechanical alloying/milling. Inter. Mater. Rev. 43(3), 101–141 (1998).

    Google Scholar 

  132. M. Qi and H. J-Fecht, Structural transition of zirconia during mechanical attrition, Mater. Sci. Forum 269-272, 187–192 (1998).

    Google Scholar 

  133. T. Tsuzuki and P. G. McCormick, Synthesis of Cr2O3 nanoparticles by mechanochemical processing, Acta mater. 48(11), 2795–2801 (2000).

    Google Scholar 

  134. O. K. Tan, W. Cao, Y. Hu, and W. Zhu, Nanostructured oxides by high-energy ball milling technique: application as gas sensing materials, Solid Stale Ion. 172, 309–316 (2004).

    Google Scholar 

  135. S. Ram and S. Biswas, Indian Patent 1981 30 (2005).

    Google Scholar 

  136. M. P. Klug and L. E. Alexander, X-ray Diffraction Procedure for Polycrystalline and Amorphous Materials (Wiley, New York, 1974).

    Google Scholar 

  137. Y. Shibasaki, F. Kanamaru, and M. Koizumi, The conversion from CrO2 into orthorhombic CrOOH, Mater. Res. Bull. 8(5), 559–564 (1973).

    Google Scholar 

  138. W. Krakow, H. Colign, and O. Müller, Phil. Magn. A 41(3), 369–384 (1980).

    Google Scholar 

  139. Z. C. Wang, T. J. Davies, N. Ridley, and A. A. Ogwu, Superplasticity of ceramic materials—II. Effect of initial porosity and doping on the superplasiic behaviour of alumina,Ada. Mater. 44(11), 4301–4309(1996).

    Google Scholar 

  140. H. Yang, A. Kuperman, N. Coombs, S. M. Afara, and G. A. Ozin, Synthesis of oriented films of mesoporous silica on mica, Nature 379, 703–705 (1996).

    Google Scholar 

  141. S. H. Joo, S. J. Choi, I. Oh, J. Kwak, Z. Liu, O. Terasaki, and R. Ryoo. Ordered nanoporous arrays of carbon supporting high dispersions of platinum nanoparticles. Nature 412, 169–172 (2001).

    Google Scholar 

  142. S. lnagaki, S. Guan, T. Ohsuna, and O. Terasaki, An ordered mesoporous organosilica hybrid material with a crystal-like wall structure, Nature 416, 304–307 (2002).

    Google Scholar 

  143. M. E. Davis, Ordered porous materials for emerging applications, Nature 417, 813–821 (2002).

    Google Scholar 

  144. T. Sun, and J.Y. Ying, Synthesis of microporous transition-metal-oxide molecular sieves by a supramolecular templating mechanism, Nature 389, 704–706 (1997).

    Google Scholar 

  145. W. Cai, Y. Zhang, J. Jia, and L. Zhang, Semiconducting optical properties of silver/silica mesoporous composite, Appl. Phys. Lett. 73(19), 2709–2711 (1998).

    Google Scholar 

  146. O. Jessensky, F. Muller, and U. Gosele. Self-organized formation of hexagonal pore arrays in anodic alumina, Appl. Phys. Lett. 72(10), 1173–1175 (1998).

    Google Scholar 

  147. S. Kondoh, Y. Iwamoto, K. Kikuta, and S. Hirano, Novel processing for mesoporous silica films with one-dimensional through channels normal to the substrate surface, J. Am. Ceram. Soc. 82(1), 209–212 (1999).

    Google Scholar 

  148. H. Gleiter, Nanostructured materials: basic concepts and microstructure, Acta Mater. 48(1), 1–29 (2000).

    Google Scholar 

  149. Y. Sakamoto, M. Kaneda, O. Terasaki, D.Y. Zhao, J. M. Kim, G. Stucky, H. J. Shin, and R. Ryoo, Direct imaging of the pores and cages of three-dimensional mesoporous materials, Nature 408, 449–453 (2000).

    Google Scholar 

  150. S. Ram and S. Rana. Synthesis of porous Al2O3 ceramic clusters by surface hydrolysis of a thin Al-metal plate in water, Mater. Sci. & Eng. A 304-306, 790–795 (2001).

    Google Scholar 

  151. P. Mohanty and S. Ram, (a) Confined growth in Eu2O3 nanocrystals in a new polymorph in an amorphous mesoporous Al2O3, Phil, Magn. B 82, 1129–1144 (2002), and (b) Enhanced photoemission in dispersed Eu2O3 nanoparticles in amorphous Al2O3, J. Mater. Chem. 13, 3021–3028 (2003).

    Google Scholar 

  152. S. Ram, Dynamics of formation of self-organized mesoporous AlO(OH).αH2O structure in Al-metal surface hydrolysis in humid air. J. Am. Ceram. Soc. 86(12), 2037–2043 (2003).

    Google Scholar 

  153. A. Mondai and S. Ram, Synthesis of nanoparticles of monolithic zirconia in a new polymorphs in orthorhombic crystal structure, Chem. Phys. Lett. 382, 297–306 (2003).

    Google Scholar 

  154. P. Mohanty and S. Ram, Multiple light emission associated with the 5D0 → 7F3 forbidden transition in Eu3+ cations dispersed in a Eu3+:Al2O3 mesoporous structure, Phil. Magn. Lett. (in press).

    Google Scholar 

  155. H. van Leuken and R. A. de Grool. Electronic structure of the chromium dioxide (001) surface. Phys. Ren B 51(11), 7176–7178 (1995).

    Google Scholar 

  156. J. B. Goodenough, Metallic oxides, Prog. Solid State Chem. 5, 145–399 (1971).

    Google Scholar 

  157. P. I. Sorantin and K. Schwarz, Chemical bonding in rutile-type compounds, Inorg. Chem. 31(4), 567–576(1992).

    Google Scholar 

  158. C. Zener. Interaction between the d-shells in the transition metals. II. Ferromagnetic compounds of manganese with perovskite structure, Phys. Rev. 82(3), 403–405 (1951).

    Google Scholar 

  159. A. R. Williams, J. Kübier, and C. D. Gelatt Jr., Cohesive properties of metallic compounds: augmented-spherical-wave calculations, Phys. Rev. B 19(12), 6094–6118 (1979).

    Google Scholar 

  160. Y. J. Chen, X. Y. Zhang, and Z. Y. Li, Role of grain boundaries on magnetoresistance of CrO2-TiO2 composites: impedance spectroscopy study, J. Magn. & Magn. Mater. 267, 152–160 (2003).

    Google Scholar 

  161. Q. Zou, H. E. Ruda, B. G. Yacobi, K. Saegusa, and M. Farrell. Dielectric properties of lead zirconate titanate thin films deposited on metal foils, Appl. Phys. Lett. 77(7), 1038–1040 (2000).

    Google Scholar 

  162. H. B. Park, C. Y. Park, Y. S. Hong, K. Kim, and S. J. Kim, Structural and dielectric properties of PLZT ceramics modified with lanthanide ions. J. Am. Ceram. Soc. 82(1), 94–102 (1999).

    Google Scholar 

  163. R. Rai, S. Sharma, and R. N. P. Choudhary, Dielectric and piezoelectric studies of Fe doped PLZT ceramics, Mater. Lett. 59, 3921–3925 (2005).

    Google Scholar 

  164. S. Canulescu, G. Dinescu, G. Epurescu, D. G. Matei, C. Grigoriu, F. Crachin, P. Verardi. and M. Dinescu. Properties of BaTiO3 thin films deposited by radiofrequency beam discharge assisted pulsed laser deposition, Mater. Sci. & Eng. B 109, 160–166 (2004).

    Google Scholar 

  165. I. S. Zheludev, Physics of crystalline dielectrics (Plenum Press, New York, 1971).

    Google Scholar 

  166. R. N. P. Choudhary, R. Palai, and S. Sharma, Structural, dielectric and electrical properties of lead cadmium tungstate ceramics, Mater. Sc. & Engg. B 77, 235–240 (2000).

    Google Scholar 

  167. R. Palai, R. N. P. Choudhary, and H. S. Tewari, Structural and dielectric properties of Ba4R2Ti4Nb6O30 (R=Y, Sm and Dy) ferroelectric ceramics, J. Phys. Chem. Solids 62, 695–700 (2001).

    Google Scholar 

  168. M. Thirumal and A. K. Ganguli, Studies on dielectric oxide materials containing niobium and tantalum, Prog. Crystal Growth and Charaet. 44, 147–154 (2002).

    Google Scholar 

  169. A. Wu, P. M. Vilarinho, I. M. M. Salvado, and J. L. Baptista, Sol-gel preparation of lead zirconate titanate powders and ceramics: Effect of alkoxidc stabilizers and lead precursors, J. Am. Ceram. Soc. 83(6), 1379–1385 (2000).

    Google Scholar 

  170. A. M. Abo El Ata and M. A. Ahmed. Dielectric and AC conductivity for BaCo2−x CuxFe16O27 ferrites, J. Magn. & Magn. Mater. 208, 27–36 (2000).

    Google Scholar 

  171. K. Bouayad, S. Sayouri, T. Lamcharfil, M. Ezzejari, D. Mezzane, L. Hajji, A. E. Ghazouali, M. Filalil, P. Dieudonne, and M. Rhoula, Sol-gel processing and dielectric properties of (Pb1−y Lay(Zr0.52Ti0.48)O3 ceramics, Physica A 358, 175–183 (2005).

    Google Scholar 

  172. P. H. Xiang, X. L. Dong, C. D. Feng, R. H. Liang, and Y. L. Wang, Dielectric behavior of lead zirconate titanate/silver composites, Mater. Chem. Phys. 97, 410–414 (2006).

    Google Scholar 

  173. C. M. Fu, C. J. Lai, J. S. Wu, J. C. A. Huang, C.-C. Wu, and S.-G. Shyu, High frequency impedance spectra on the chromium dioxide thin film, J. Appl. Phys. 89(11), 7702–7704 (2001).

    Google Scholar 

  174. C. M. Fu, C. J. Lai, H. S. Hsu, Y. C. Chao, J. C. A. Huang, C.-C. Wu, and S.-G. Shyu, Characterization of magneloimpedance on polycrystalline and amorphous chromium oxides bilayered thin films, J. Appl. Phys. 91(10), 7143–7145 (2002).

    Google Scholar 

  175. C. M. Fu, Y. C. Chao, S. H. Hung, C. P. Lin, and J. Tang, Impedance spectra of field-aligned CrO2 needle-shape powders, J. Magn. & Magn. Mater. 282, 283–286 (2004).

    Google Scholar 

  176. J. M. D. Coey, A. E. Berkowitz, L. Balcells, F. F. Putris, and A. Barry, Magnetoresistance of chromium dioxide powder compacts, Phys. Rev. Lett. 80(17), 3815–3818 (1998).

    Google Scholar 

  177. S. S. Manoharan, D. Elefant, G. Reiss, and J. B. Goodenough, Extrinsic giant magnetoresistance in chromium (IV) oxide, CrO2, Appl. Phys. Lett. 72(8), 984–986 (1998).

    Google Scholar 

  178. S. M. Watts, S. Wirth, S. von Molnar, A. Barry, and J. M. D. Coey. Evidence for twoband magnetotransport in half-metallic chromium dioxide, Phys. Rev. B 61(14), 9621–9628 (2000).

    Google Scholar 

  179. P. A. Stampe, R. J. Kennedy, S. M. Watts, and S. von Molnar, Strain effects in thin films of CrO2 on rutile and sapphire substrates, J. Appl. Phys. 89(11), 7696–7698 (2001).

    Google Scholar 

  180. A. Barry, J. M. D. Coey, L. Ranno, and K. Ounadjela, Evidence for a gap in the excitation spectrum of CrO2, J. Appl. Phys. 83(11), 7166–7168 (1998).

    Google Scholar 

  181. J. Inoue and S. Maekawa, Theory of tunneling magnetoresistance in granular magnetic films, Phys. Rev. B 53(18), 11927–11929 (1996).

    Google Scholar 

  182. T. Zhu and Y. J. Wang, Enhanced tunneling magnetoresistance of Fe-Al2O3 granular films in the coulomb blockade regime, Phys. Rev. B 60(17), 11918–11921 (1999).

    Google Scholar 

  183. Y. J. Chen, X. Y. Zhang, T. Y. Cai, and Z. Y. Li, Study of the conductance and magnetotransport of CrO2-TiO2 composites, Mater. Lett. 58, 262 (2004).

    Google Scholar 

  184. C. H. Shang, J. Nowak, R. Jansen, and J. S. Moodera, Temperature dependence of magnetoresistance and surface magnetization in ferromagnetic tunnel junctions, Phys. Rev. B 58(6), 2917–2920 (1998).

    Google Scholar 

  185. L. I. Glazman and K. A. Matveev, Inelastic tunneling across thin amorphous films, Sow Phys. JETP 67 (6), 1276–1282 (1988).

    Google Scholar 

  186. F. Y. Yang, C. L. Chien, E. F. Ferrari, X. W. Li, G. Xiao, and A. Gupta, Uniaxial anisotropy and switching behavior in epitaxial CrO2 films, Appl. Phys. Lett. 77(2), 286–288 (2000).

    Google Scholar 

  187. J. K. Burden, G. J. Miller, J. W. Richardson. Jr., and J. V. Smith, Low-temperature neutron powder diffraction study of CrO2 and the validity of the Jahn-Teller viewpoint, J. Am. Chem. Soc. 110, 8064–8071 (1988).

    Google Scholar 

  188. X. W. Li, A. Gupta, and G. Xiao, Influence of strain on the magnetic properties of epitaxial (100) chromium dioxide (CrO2) films, Appl. Phys. Lett. 75(5), 713–715 (1999).

    Google Scholar 

  189. S. Ram, Development of planar hexagonal Fe2-Y ferrite particles for millimeter wave devices. J. Magn. & Magn, Mater. 72, 315–318 (1988).

    Google Scholar 

  190. S. Ram and J. C. Joubert. Variation in particle morphology and Curie temperature of SrZn2Fe16O27 ceramic powders, Phys. Rev. B 44, 6825–6831 (1991).

    Google Scholar 

  191. S. Ram and J. C. Joubert, Development of high quality ceramic powders of Sr0.9Ca0.1Zn2-W type hexagonal ferrite for permanent magnet devices, IEEE. Trans. Magn. 28, 15–20 (1992).

    Google Scholar 

  192. P. Lubitz, M. Rubinstein, M. S. Osofsky, B. E. Nadgorny, R. J. Soulen, K. M. Bussmann, and A. Gupta, Ferromagnetic resonance observation of exchange and relaxation effects in CrO2, J. Appl. Phys. 89(11), 6695–6697 (2001).

    Google Scholar 

  193. A. Gupta, X. W. Li, and G. Xiao, Inverse magnetoresistance in chromium-dioxide-based magnetic tunnel junctions, Appl. Phys. Lett. 78(13), 1894–1896 (2001).

    Google Scholar 

  194. Y. Xu, D. Ephron, and M. R. Beasley. Directed inelastic hopping of electrons through metal-insulator-melal tunnel junctions, Phys. Rev. B 52(4), 2843–2859 (1995).

    Google Scholar 

  195. H. Itoh, T. Ohsawa, and J. Inoue, Magnetoresistance of ferromagnetic tunnel junctions in the double-exchange model, Phys. Rev. Lett. 84(11), 2501–2504 (2000).

    Google Scholar 

  196. V. Petricevic, S. K. Gayen, and R. R. Alfano, Laser action in chromium-activated forsterite for near-infrared excitation: Is Cr4+ the lasing ion?, Appl. Phys. Lett. 53(26), 2590–2592 (1988).

    Google Scholar 

  197. N. V. Kulcshov, V. P. Mikhailov, V. G. Scherbitsky, B. I. Minkov, T. J. Glynn, and R. Sherlock, Luminescence study of Cr4+-doped silicates, Opt. Mater. 4, 507–513 (1995).

    Google Scholar 

  198. X. Wu, H. Yuan, W. M. Yen, and B. G. Aitken, Compositional dependence of the luminescence from Cr4+-doped calcium aluminale glass, J. Lumin. 66 & 67, 285–289 (1996).

    Google Scholar 

  199. B. Lipavsky, Y. Kalisky, Z. Burshtein, Y. Shimony, and S. Rotman. Some optical properties of Cr4+-doped crystals, Opt. Mater. 13, 117–127 (1999).

    Google Scholar 

  200. X. Feng and S. Tanabe, Spectroscopy and crystal-field analysis for Cr(lV) in alumino-silicate glasses, Opt. Mater. 20, 63–72 (2002).

    Google Scholar 

  201. Y. Tanabe and S. Sugano, The absoiption spectra of complex ions, J. Phys. Sac. Jpn. 9, 753–766 (1954).

    Google Scholar 

  202. D. F. Shrirer, P. W. Atkins, and C. H. Langford, Inorganic Chemistry (Wiley, New York, 1990).

    Google Scholar 

  203. A. Paul, Chemistry of Glasses (Chapman and Hall, London, 1990).

    Google Scholar 

  204. S. Ram, K. Ram. and B. S. Shukla, Optical absorption and FPR studies of borate glasses with PbCrO4 and Pb2CrO5 microcrystals, J. Mater. Sci. 27, 511–519 (1992).

    Google Scholar 

  205. R. Bhalt, S. Kar, K. S. Barlwal, and V. K. Wadhawan, The effect of Cr doping on optical and photoluminescence properties of LiNbO3 crystals, Solid State Commun. 127, 457–462 (2003).

    Google Scholar 

  206. S. Ram, Synthesis and structural and optical properties of metaslable ZrO2 nanoparticles with intergranular Cr3+/Cr4+ doping and grain surface modification, J. Mater. Sci. 38, 643–655 (2003).

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Materials Science Centre, Indian Institute of Technology, Kharagpur, 721302, India

    S. Ram & S. Biswas

  2. Division of Electronic Materials, University of Ulm, Albert Einstein Allee 47, Ulm, D-89061, Germany

    H. J-Fecht

Authors
  1. S. Ram
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. S. Biswas
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. H. J-Fecht
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to S. Ram .

Editor information

Editors and Affiliations

  1. Advanced Materials Processing and Analysis Center, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida, 32816-2455

    Sudipta Seal

Rights and permissions

Reprints and permissions

Copyright information

© 2008 Springer Science+Business Media, LLC

About this chapter

Cite this chapter

Ram, S., Biswas, S., J-Fecht, H. (2008). Advanced Ceramics and Nanocomposites of Half-metallic Ferromagnetic CrO2 for Magnetic, GMR and Optical Sensors. In: Seal, S. (eds) Functional Nanostructures. Nanostructure Science and Technology. Springer, New York, NY. https://doi.org/10.1007/978-0-387-48805-9_1

Download citation

Publish with us

Policies and ethics

Search

Navigation