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22 Jul 2002

Volume 81, Issue 4, pp. 571-782

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Photoluminescence stabilization of anodically-oxidized porous silicon layers by chemical functionalization

Rabah Boukherroub, Danial D. M. Wayner, and David J. Lockwood

Appl. Phys. Lett. 81, 601 (2002); http://dx.doi.org/10.1063/1.1492306 (3 pages) | Cited 24 times

Online Publication Date: 16 July 2002

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Electrochemical oxidation of porous silicon (PSi) produces a surface that is covered with native silicon–hydrogen (Si–Hx) bonds and regions with oxidized Si–Si back-bonds (OSi–Hx). Such anodically oxidized PSi layers were chemically modified using 1-decene under thermal conditions. The hydrosilylation reaction consumes mainly the nonoxidized Si–Hx bonds and yields a surface with oxidized and alkylated regions that were characterized using transmission IR and Raman spectroscopies. The brightest photoluminescence (PL) was obtained when the PSi sample was anodized in 1 M sulfuric acid (H2SO4) at 3 mA/cm2 for 5 min. The chemical process preserves the PL and the physical properties of the porous layer. The derivatized PSi surfaces are stable in boiling CCl4 and in water. © 2002 American Institute of Physics.
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81.65.Rv Passivation
81.65.Mq Oxidation
78.55.Ap Elemental semiconductors
82.45.Jn Surface structure, reactivity and catalysis
78.55.Mb Porous materials
78.30.Am Elemental semiconductors and insulators

AlN/AlGaN superlattices as dislocation filter for low-threading-dislocation thick AlGaN layers on sapphire

Hong-Mei Wang, Jian-Ping Zhang, Chang-Qing Chen, Q. Fareed, Jin-Wei Yang, and M. Asif Khan

Appl. Phys. Lett. 81, 604 (2002); http://dx.doi.org/10.1063/1.1494858 (3 pages) | Cited 55 times

Online Publication Date: 16 July 2002

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We report on an approach of using AlN/AlGaN superlattices (SLs) for threading-dislocation-density reduction to grow high quality thick AlGaN on sapphire. Using x-ray diffraction (XRD) measurements and etch pits counting by atomic force microscopy, we show that the insertion of AlN/AlGaN SLs suppresses the material mosaicity and decreases the threading dislocation density by two orders of magnitude, and then eliminates cracking. Dislocation densities deduced from the XRD results and those from chemical etching are in a good agreement. © 2002 American Institute of Physics.
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68.65.Cd Superlattices
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.37.Ps Atomic force microscopy (AFM)
81.05.Ea III-V semiconductors
85.60.Jb Light-emitting devices

Structural characterization of a porous low-dielectric-constant thin film with a non-uniform depth profile

Eric K. Lin, Hae-Jeong Lee, Gary W. Lynn, Wen-li Wu, and Mark L. O’Neill

Appl. Phys. Lett. 81, 607 (2002); http://dx.doi.org/10.1063/1.1495079 (3 pages) | Cited 6 times

Online Publication Date: 16 July 2002

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High-resolution x-ray reflectivity (XR) and small-angle neutron scattering (SANS) are applied to characterize both the nonuniform depth profile and pore structure of a low-dielectric-constant (low-k) thin film as prepared on a silicon substrate. The XR data show that the density depth profile has a multilayered structure with a dense, nonporous top layer and a less dense, porous bulk layer. A scattering invariant analysis of the SANS data is used to determine the average chord length of the pores, (14.8±2.0) nm, independent of the depth profile. Given the elemental composition of the film, the XR and SANS data are combined to calculate the mass density of the top layer, (1.13±0.05) g/cm3, the porosity of the less dense layer, (0.28±0.10), and the wall density, (0.92±0.15) g/cm3. © 2002 American Institute of Physics.
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77.84.Jd Polymers; organic compounds
77.55.-g Dielectric thin films
68.55.-a Thin film structure and morphology
77.22.Ch Permittivity (dielectric function)

Direct transformation of cubic diamond to hexagonal diamond

Hongliang He, T. Sekine, and T. Kobayashi

Appl. Phys. Lett. 81, 610 (2002); http://dx.doi.org/10.1063/1.1495078 (3 pages) | Cited 22 times

Online Publication Date: 16 July 2002

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For a long time, hexagonal diamond has been formed only by static and shock wave compression of well-crystallized graphites. Here, we demonstrate that cubic diamond loses its structure stability and transforms to hexagonal diamond in massive. This transformation has been completed in nanoseconds under a shock wave compression of cubic diamond, in which the shock pressure and temperature are only tens of giga pascal and hundreds of kelvin, thermodynamically being within the stability of cubic diamond. The formation of hexagonal diamond is interpreted as a direct transition (solid to solid) of cubic diamond by a kinetic mechanism due to the shear stress and enhanced temperature induced by the rapid shock wave compression. © 2002 American Institute of Physics.
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64.70.K- Solid-solid transitions
62.50.-p High-pressure effects in solids and liquids

Role of the wetting layer in the carrier relaxation in quantum dots

S. Sanguinetti, K. Watanabe, T. Tateno, M. Wakaki, N. Koguchi, T. Kuroda, F. Minami, and M. Gurioli

Appl. Phys. Lett. 81, 613 (2002); http://dx.doi.org/10.1063/1.1495525 (3 pages) | Cited 31 times

Online Publication Date: 16 July 2002

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We present picosecond time resolved photoluminescence measurements of GaAs/AlGaAs quantum dot structures—grown by modified droplet epitaxy—where no wetting layer is connecting the dots. We find a fast carrier relaxation time (30 ps) to the dot ground state, which becomes even faster for increasing the photogenerated carrier injection. This shows that the two–dimensional character of the wetting layer is not relevant in determining the quantum dot capture, in contrast with the conclusions of several models so far presented in literature. We discuss the role of the barrier states as well as the possibility of Auger processes involving the zero-dimensional levels of the quantum dots. © 2002 American Institute of Physics.
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73.21.La Quantum dots
78.67.Hc Quantum dots
73.63.Kv Quantum dots
81.07.Ta Quantum dots
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
81.05.Ea III-V semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.47.-p Spectroscopy of solid state dynamics

Large-scale ordered macroporous SiO2 thin films by a template-directed method

Yong-Hong Ye, Simona Badilescu, and Vo-Van Truong

Appl. Phys. Lett. 81, 616 (2002); http://dx.doi.org/10.1063/1.1495902 (3 pages) | Cited 15 times

Online Publication Date: 16 July 2002

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Ordered three-dimensional macroporous SiO2 films were fabricated by colloidal crystal templating. Scanning electron microscope measurements showed that the size of the air sphere replicates that of the initial polystyrene spheres, and that the porous sample exhibits long-range order. Optical measurements show that the macroporous sample exhibits the behavior of a photonic band gap, indicating crystalline order in the sample. Fourier-transform infrared measurements revealed that a strong network of Si–O–Si bonds have been formed throughout the voids of the template before the solidification of the gel. It is proposed that this network hinders the large volume shrinkage during the subsequent heat treatment, and thus high-quality large-scale ordered macroporous films can be obtained. © 2002 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.05.Rm Porous materials; granular materials
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
78.66.Nk Insulators
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
61.43.Gt Powders, porous materials
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
42.70.Qs Photonic bandgap materials
81.40.Gh Other heat and thermomechanical treatments
61.72.Qq Microscopic defects (voids, inclusions, etc.)
61.50.Lt Crystal binding; cohesive energy
78.30.Hv Other nonmetallic inorganics

Metal–insulator transition at room temperature and infrared properties of Nd0.7Eu0.3NiO3 thin films

F. Capon, P. Laffez, J.-F. Bardeau, P. Simon, P. Lacorre, and M. Zaghrioui

Appl. Phys. Lett. 81, 619 (2002); http://dx.doi.org/10.1063/1.1493645 (3 pages) | Cited 15 times

Online Publication Date: 16 July 2002

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Nd0.7Eu0.3NiO3 thin films are deposited by rf sputtering and subsequent oxygen pressure annealing on (100) oriented silicon substrate. We characterize the thermochromic properties of films by measuring electrical transition, infrared transmittance, and reflectance. The thermochromic effect at room temperature is observed. Resistivity measurements exhibit a sharper hysteresis loop than is usually observed in NdNiO3 thin films. Infrared properties in the 8–14 μm wavelength range spectra reveal a contrast of 30% in reflectance and 55% in transmittance. © 2002 American Institute of Physics.
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71.30.+h Metal-insulator transitions and other electronic transitions
72.60.+g Mixed conductivity and conductivity transitions
78.66.Nk Insulators
81.40.Rs Electrical and magnetic properties related to treatment conditions
73.50.Dn Low-field transport and mobility; piezoresistance
73.61.Ng Insulators
78.30.Hv Other nonmetallic inorganics
78.20.N- Thermo-optic effects
78.20.nb Photothermal effects
81.40.Gh Other heat and thermomechanical treatments
81.40.Tv Optical and dielectric properties related to treatment conditions
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Role of copper in the green luminescence from ZnO crystals

N. Y. Garces, L. Wang, L. Bai, N. C. Giles, L. E. Halliburton, and G. Cantwell

Appl. Phys. Lett. 81, 622 (2002); http://dx.doi.org/10.1063/1.1494125 (3 pages) | Cited 216 times

Online Publication Date: 16 July 2002

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Electron paramagnetic resonance (EPR), photoluminescence, and infrared optical absorption have been used to investigate a ZnO crystal before and after a thermal anneal for 1 h in air at 900 °C. The sample was an undoped high quality crystal grown by the chemical vapor transport method. In addition to shallow donor impurities, the crystal contained trace amounts of copper ions. Prior to the thermal anneal, these ions were all in the Cu+ (3d10) state and the observed luminescence at 5 K, produced by 364 nm light, consisted of a broad structureless band peaking at 500 nm. After the high-temperature anneal, the Cu2+ (3d9) EPR spectrum was observed and the luminescence had changed significantly. The emission then peaked near 510 nm and showed structure identical to that reported by Dingle [Phys. Rev. Lett. 23, 579 (1969)]. Our data reaffirm that the structured green emission in ZnO is associated with Cu2+ ions. We suggest that the unstructured green emission (observed before the high-temperature anneal) is donor–acceptor pair recombination involving the Cu+ acceptors. © 2002 American Institute of Physics.
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78.55.Et II-VI semiconductors
71.55.Gs II-VI semiconductors
81.05.Dz II-VI semiconductors
78.30.Fs III-V and II-VI semiconductors
76.30.Fc Iron group (3d) ions and impurities (Ti-Cu)
61.72.Cc Kinetics of defect formation and annealing
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Local order of Sb and Bi dopants in hydrogenated amorphous germanium thin films studied by extended x-ray absorption fine structure

G. Dalba, P. Fornasini, R. Grisenti, F. Rocca, and I. Chambouleyron

Appl. Phys. Lett. 81, 625 (2002); http://dx.doi.org/10.1063/1.1496137 (3 pages) | Cited 2 times

Online Publication Date: 16 July 2002

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This letter reports on the investigation of the local order and coordination of Sb and Bi impurities in hydrogenated amorphous germanium thin films. The study uses the extended x-ray absorption fine structure technique in fluorescence mode at room temperature. The investigation includes doping concentrations ranging from 1.1×1019 to 5×1020 cm−3. For both impurities, the evidence is that the thermal equilibrium model is not applicable in this case. This result qualitatively follows the behavior of Ga and In impurities in hydrogenated amorphous germanium (a-Ge:H) samples except for Bi. These findings are consistent with data on the transport properties of Sb- and Bi-doped a-Ge:H films. © 2002 American Institute of Physics.
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61.43.Dq Amorphous semiconductors, metals, and alloys
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.05.Cy Elemental semiconductors
81.05.Gc Amorphous semiconductors
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
78.70.Dm X-ray absorption spectra
71.55.Cn Elemental semiconductors
61.72.uf Ge and Si

Pseudodielectric function of ZnGeP2 from 1.5 to 6 eV

V. Blickle, K. Flock, N. Dietz, and D. E. Aspnes

Appl. Phys. Lett. 81, 628 (2002); http://dx.doi.org/10.1063/1.1492022 (3 pages) | Cited 2 times

Online Publication Date: 16 July 2002

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We report pseudodielectric function data 〈ε〉 = 〈εa1〉+i〈εa2〉 and 〈ε〉 = 〈εc1〉+i〈εc2〉 for the optically uniaxial material ZnGeP2, critical point energies of structures in these data, and dielectric function data for the natural oxide. Annealing reduces the values of the peaks of 〈εa2〉. © 2002 American Institute of Physics.
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77.22.Ch Permittivity (dielectric function)
81.05.Hd Other semiconductors
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Epitaxial growth of dielectric CaCu3Ti4O12 thin films on (001) LaAlO3 by pulsed laser deposition

Y. Lin, Y. B. Chen, T. Garret, S. W. Liu, C. L. Chen, L. Chen, R. P. Bontchev, A. Jacobson, J. C. Jiang, E. I. Meletis, J. Horwitz, and H.-D. Wu

Appl. Phys. Lett. 81, 631 (2002); http://dx.doi.org/10.1063/1.1490624 (3 pages) | Cited 55 times

Online Publication Date: 16 July 2002

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High dielectric CaCu3Ti4O12 (CCTO) thin films were epitaxially grown on (001) LaAlO3 (LAO) substrates by pulsed laser deposition. Microstructural studies by x-ray diffraction, pole figure measurements, and transmission electron microscopy show that the as-grown films are good single crystalline quality with an interface relationship of (001)CCTO//(001)LAO and [100]CCTO//[100]LAO. Dielectric property measurements show that the films have an extremely high dielectric constant with value of 10 000 at 1 MHz at room temperature. It is interesting to note that the twinned substrate results in the formation of twinning or dislocations inside the CCTO film. © 2002 American Institute of Physics.
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81.15.Fg Pulsed laser ablation deposition
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
68.55.-a Thin film structure and morphology
77.22.Ch Permittivity (dielectric function)
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Thermal annealing below the glass transition temperature: A general way to increase performance of light-emitting diodes based on copolyfluorenes

Yu-Hua Niu, Qiong Hou, and Yong Cao

Appl. Phys. Lett. 81, 634 (2002); http://dx.doi.org/10.1063/1.1495898 (3 pages) | Cited 23 times

Online Publication Date: 16 July 2002

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Polymer light-emitting diodes based on copolyfluorene with barium/aluminum cathode were thermally annealed at different temperatures through different time periods. It was found that by annealing just below the glass transition temperature (sub-Tg) of these copolymers the device performance was greatly enhanced. Lower turn-on voltage, higher maximum brightness, and more than two times higher external electroluminescent (EL) quantum efficiency could be achieved in this way. We found out that the enhancement in electron injection and the increase in carrier mobility after thermal annealing at a temperature close to Tg of the EL polymers are responsible for the improvement in device performance. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
42.70.Jk Polymers and organics

Capacitance–voltage studies of Al-Schottky contacts on hydrogen-terminated diamond

J. A. Garrido, C. E. Nebel, M. Stutzmann, E. Snidero, and P. Bergonzo

Appl. Phys. Lett. 81, 637 (2002); http://dx.doi.org/10.1063/1.1496495 (3 pages) | Cited 14 times

Online Publication Date: 16 July 2002

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The electrical properties of Al contacts on hydrogen-terminated diamond have been characterized. Capacitance–voltage experiments were carried out in order to obtain further insight into the origin of the Schottky contact behavior of Al. Schottky diodes with different areas and peripheries were fabricated and analyzed. We have found that the capacitance of these structures is not proportional to the area but to the length of the contact periphery, supporting the two-dimensional nature of the surface charge layer in hydrogen-terminated diamond. A model based on the negative electron affinity of hydrogen-terminated diamond and the work function of Al is used to explain the in-plane capacitance of the Al Schottky contacts. © 2002 American Institute of Physics.
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73.30.+y Surface double layers, Schottky barriers, and work functions
81.05.U- Carbon/carbon-based materials
81.05.Bx Metals, semimetals, and alloys
73.40.Ns Metal-nonmetal contacts
81.05.Cy Elemental semiconductors
85.30.Hi Surface barrier, boundary, and point contact devices
85.30.Kk Junction diodes

Influence of the growth procedure on the Cd distribution in CdSe/ZnSe heterostructures: Stranski–Krastanov versus two-dimensional islands

D. Litvinov, A. Rosenauer, D. Gerthsen, P. Kratzert, M. Rabe, and F. Henneberger

Appl. Phys. Lett. 81, 640 (2002); http://dx.doi.org/10.1063/1.1496133 (3 pages) | Cited 30 times

Online Publication Date: 16 July 2002

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Molecular beam epitaxy is used to grow different types of ZnSe/CdSe/ZnSe heterostructures. The topography of the bare CdSe surface studied with in situ atomic force microscopy is compared with high-resolution transmission electron microscopy data on overgrown structures. The growth procedure critically influences morphology and Cd distribution. Only use of thermal activation after low-temperature CdSe deposition enables the accomplishment of a distinct Stranski–Krastanov (SK) morphology with three-dimensional islands with a core of pure CdSe. Interdiffusion effects during activation of the SK transition as well as overgrowth are of minor importance. © 2002 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.Ct Interface structure and roughness
68.55.-a Thin film structure and morphology
81.05.Dz II-VI semiconductors
68.37.Ps Atomic force microscopy (AFM)
68.37.Lp Transmission electron microscopy (TEM)
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation

Boron suboxide: As hard as cubic boron nitride

Duanwei He, Yusheng Zhao, L. Daemen, J. Qian, T. D. Shen, and T. W. Zerda

Appl. Phys. Lett. 81, 643 (2002); http://dx.doi.org/10.1063/1.1494860 (3 pages) | Cited 61 times

Online Publication Date: 16 July 2002

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The Vickers hardness of boron suboxide single crystals was measured using a diamond indentation method. Under a loading force of 0.98 N, our test gave an average Vickers hardness of 45 GPa. The average fracture toughness was measured as 4.5 MPa m1/2. We also measured the hardness of the cubic boron nitride and sapphire single crystals for comparison. The average measured hardness for boron suboxide was found to be very close to that of cubic boron nitride under the same loading force. Our results suggest that the boron suboxide could be a new superhard material for industrial applications, surpassed in hardness only by diamond and cubic boron nitride. © 2002 American Institute of Physics.
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81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp Friction, tribology, and hardness
62.20.M- Structural failure of materials

Sensitive imaging of an elastic nonlinear wave-scattering source in a solid

Vyacheslav V. Kazakov, Alexander Sutin, and Paul A. Johnson

Appl. Phys. Lett. 81, 646 (2002); http://dx.doi.org/10.1063/1.1495081 (3 pages) | Cited 29 times

Online Publication Date: 16 July 2002

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We have developed an imaging method for locating isolated nonlinear scattering source(s) in solids. It relies on extracting the nonlinear response of a solid by modulation of a high by a low-frequency wave, and employing moving-window, synchronous detection. The resulting image consists of nonlinear wave reflection profiles with remarkable sensitivity to an isolated elastic nonlinear source(s). In creating the image, we can distinguish between a nonlinear scattering source and other wave scatterers in the material. The method should work equally well for imaging the relative nonlinearity of different regions within a volume. © 2002 American Institute of Physics.
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46.40.Cd Mechanical wave propagation (including diffraction, scattering, and dispersion)
43.25.Dc Nonlinear acoustics of solids

Interband optical properties of higher manganese silicide thin films

M. Rebien, W. Henrion, H. Angermann, and S. Teichert

Appl. Phys. Lett. 81, 649 (2002); http://dx.doi.org/10.1063/1.1496135 (3 pages) | Cited 8 times

Online Publication Date: 16 July 2002

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Semiconducting MnSi1.7 has been investigated by ellipsometric as well as reflectance and transmittance measurements. The interband dielectric functions of epitaxial films on Si(001) and polycrystalline films have been determined. Below the lowest direct transition at 0.96 eV, an indirect gap of 0.40 eV is obtained. The optical properties of the native oxide of MnSi1.7 are found to closely resemble those of SiO2. © 2002 American Institute of Physics.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.Li Other semiconductors
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons

Exciton spectra of an AlN epitaxial film on (0001) sapphire substrate grown by low-pressure metalorganic vapor phase epitaxy

T. Onuma, S. F. Chichibu, T. Sota, K. Asai, S. Sumiya, T. Shibata, and M. Tanaka

Appl. Phys. Lett. 81, 652 (2002); http://dx.doi.org/10.1063/1.1493666 (3 pages) | Cited 29 times

Online Publication Date: 16 July 2002

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Exciton resonance energies in an AlN epilayer on (0001) sapphire substrate grown by low-pressure metalorganic vapor phase epitaxy were determined as a function of temperature by means of optical reflectance (OR) and cathodoluminescence measurements. The OR spectra exhibited distinct reflectance anomalies at the photon energies just above the multiple internal reflection fringes, and the spectral line shape was fitted considering A (Γ7vu→Γ7c) and BC (Γ9v,Γ7vl→Γ7c) exciton transitions. The fitting gave the values of them at 0 K to be 6.211 and 6.266 eV, giving the crystal- field splitting (Δcr) of approximately 55 meV. The AlN film exhibited an excitonic emission even at 300 K, which is due to the small Bohr radius of excitons and large longitudinal optical phonon energies. The Einstein characteristic temperature ΘE was estimated to be 580 K. © 2002 American Institute of Physics.
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78.66.Fd III-V semiconductors
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
78.60.Hk Cathodoluminescence, ionoluminescence
63.20.kk Phonon interactions with other quasiparticles
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.70.Ch Crystal and ligand fields

Local environment surrounding magnetic impurity atoms in a structural phase transition of Co-doped TiO2 nanocrystal ferromagnetic semiconductors

Y. L. Soo, G. Kioseoglou, S. Kim, Y. H. Kao, P. Sujatha Devi, John Parise, R. J. Gambino, and P. I. Gouma

Appl. Phys. Lett. 81, 655 (2002); http://dx.doi.org/10.1063/1.1495544 (3 pages) | Cited 45 times

Online Publication Date: 16 July 2002

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The local environment surrounding magnetic impurity atoms and the host crystal structure of codoped TiO2 (TiO2:Co) nanocrystal ferromagnetic semiconductors have been investigated using the x-ray absorption fine structure and powder diffraction techniques. It has been found that the magnetic Co impurity atoms substitute for the Ti sites in an anataselike local environment through a structural phase transition when the material changes from an amorphous phase to a mixture of anatase and rutile crystal structures and then to a rutile structure as a result of increasing the anneal temperature. This result reveals an interesting feature that the local structure around magnetic impurity atoms can remain practically unchanged while the material undergoes drastic structural variations and a loss of room-temperature ferromagnetism. © 2002 American Institute of Physics.
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64.70.Nd Structural transitions in nanoscale materials
61.46.-w Structure of nanoscale materials
81.07.Bc Nanocrystalline materials
75.30.Hx Magnetic impurity interactions
75.50.Tt Fine-particle systems; nanocrystalline materials
61.72.S- Impurities in crystals
64.70.K- Solid-solid transitions
61.43.-j Disordered solids
75.50.Pp Magnetic semiconductors
75.50.Dd Nonmetallic ferromagnetic materials
78.70.Dm X-ray absorption spectra
75.30.Et Exchange and superexchange interactions
81.40.Gh Other heat and thermomechanical treatments
81.40.Rs Electrical and magnetic properties related to treatment conditions
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