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Hyperspectral images (HSIs) can help deliver more reliable representations of real scenes than traditional images and enhance the performance of many computer vision tasks. However, in real cases, an HSI is often degraded by a mixture of various types of noise, including Gaussian noise and impulse noise. In this paper, we propose a logarithmic nonconvex regularization model for HSI mixed noise removal. The logarithmic penalty function can approximate the tensor fibered rank more accurately and treats singular values differently. An alternating direction method of multipliers (ADMM) is also presented to solve the optimization problem, and each subproblem within ADMM is proven to have a closed-form solution. The experimental results demonstrate the effectiveness of the proposed method.

A CN/diamond composite structure on silicon substrate was obtained by a two-step technique in preparing polycrystalline diamond layers by microwave plasma assisted chemical vapor deposition and then CN films by reactive rf magnetron sputtering. The samples were annealed at different temperatures in the range of 200 to 800 °C, respectively. All the as-grown and annealed CN films, which fully covered the diamond underlayer with the formation of a rather adhesive interface, exhibited amorphous nature uniquely. X-ray photoelectron spectroscopy and energy-dispersive x-ray studies both revealed that the nitrogen concentration of the films decreases after annealed at high temperature. Infrared spectra also suggested the thermal modifications on the content and structure of the CN films. The electric resistivity varies in a large range as the annealing temperature increasing, and confirmed the bonding configuration in favor of a graphite-like structure at high temperature.

The magnetic properties of Y(Fe 1- x Co x ) 10 Si 2 compounds with x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0 and YFe 8 M 2 Si 2 compounds with M=Fe, Ni, Co and Mn have been investigated. All investigated compounds are isotypical and crystallize in the ThMn 12 -type structure. The Co concentration dependence of the Curie temperature T c of Y(Fe 1- x Co x ) 10 Si 2 compounds exhibits a maximum. Substitution of Mn for Fe leads to a distinct decrease of T C . Substitution of Ni for Fe has no remarkable influence on T C . The X-ray diffraction patterns of magnetically aligned samples show that the easy magnetization direction at room temperature is along the c -axis for all YFe 8 M 2 Si 2 compounds with M=Fe, Co, Ni and Mn. Substitution of Mn and Ni for Fe leads to a pronounced decrease of the anisotropy field, whereas substitution of Co for Fe has no remarkable influence on the anisotropy field. The anisotropy fields of YFe 8 Mn 2 Si 2 and YFe 8 Ni 2 Si 2 increase monotonously with decreasing temperature.

Pb(Zr0.53Ti0.47)O-3 (PZT 53/47) is a polycrystalline film with coarse square-shaped grains. The surface morphology can be improved by reducing the cooling rate at the Curie temperature region; however this morphology still does not meet the requirement of device engineering. Pb(Zr0.2Ti0.8)O-3 (PZT 20/80) film has been synthesized, to reduce the lattice mismatch between PZT and substrate. This film has a smooth surface without any evident crystalline features. A TEM of the cross-sectional PZT/YBa2Cu3O7 (YBCO) integrated film shows there is no interaction between the PZT, YBCO and substrate. ZrO2 particles are detected in the PZT film.

TbMn6-xTixSn6 compounds with x = 0, 0.5, 1.0, 1.5 and 2.0 have been studied in this paper. All compounds crystallize in the HfFe6Ge6-type structure (space group, P6/mmm). The substitution of Ti for Mn in TbMn6Sn6 results in a linear increase in the lattice constants and the unit-cell volume from a = 5.531 Angstrom, c = 9.025 Angstrom and V = 239.10 Angstrom(3) at x = 0, to a = 5.588 Angstrom, c = 9.150 Angstrom and V = 247.44 Angstrom(3) at x = 2.0. The ordering temperature and the reorientation temperature of the easy axis of these compounds decrease monotonically with Ti content from 423 K and 330 K at x = 0 to 362 K and 285 K at x = 2.0. In thermal magnetic curves a new transition was found at the temperature T-f at which the magnetization begin to increase and T-f increases from 37 K at x = 0 to 150 K at x = 2.0. The saturation magnetization at room temperature decreases linearly with increasing Ti content. The magnetization curves at 1.5 K in fields up to 70 kOe are given and the magnetization values at 1.5 K are derived from them.

The magnetic properties of Y(Co 1− x Fe x ) 10 Si 2 ( x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) compounds have been studied. All compounds crystallize in ThMn 12 type structures. The lattice parameters a and c increase with increasing iron content, while the Curie temperature has a maximum at about x = 0.6. The easy magnetization direction at room temperature changes from basal plane to the c -axis at about x = 0.2. The anisotropy field obtained by the SPD technique reaches a maximum at x = 1.0, with values of 2.1 T at room temperature and 2.6 T at 77 K respectively.

A new series of compounds, Gd x Dy 1− x Fe 11.35 Nb 0.65 , with a ThMn 12 structure was synthesized. The corresponding nitrides prepared by gas solid reaction retain the structure of their parent alloys, but with an expansion of 3% of the unit cell volume. Their Curie temperature increases by about 200 K. For the alloys, the spin-reorientation transition temperature T sr1 decrease, while the Curie temperature and the magnetocrystalline anisotropy field increase with the substitution of Gd for Dy. Upon nitrogenation, the spin reorientation of the nitrides disappear, and the magnetocrystalline anisotropy field of the nitrides decrease with increasing Gd content.

In this paper, the remanence properties of Co-Sn, Co-Ti and CO-Ti-Sn substituted Ba-ferrite (BaF) oriented particulate samples are compared with those of some oriented acicular particulate samples. A new parameter, the minor remanence distribution (MRD), is proposed to review the remanence properties of magnetic particles and the capabilities for resisting the recording demagnetization of magnetic recording media. It is shown that the MRD values of the oriented BaF particulate samples were smaller compared to oriented Co-gamma-Fe2O3 samples, even though the squareness ratios (SR) of some of the BaF samples were smaller than those of the Co-gamma-Fe2O3 samples. It is the small MRD, SFD(r), IRS and large DH(r) of a medium that can result in a large resistance to the effects of recording demagnetization and therefore in superior characteristics for high density magnetic recording. Since Co-Sn substituted BaF platelet-shaped particles exhibit these characteristics and have a very low temperature coefficient of coercivity, these particles can be expected to be a promising candidate for high density magnetic recording.

In the present paper, the structure and magnetic properties of TbMn6Sn6 have been investigated. TbMn6Sn6 is found to be of HfFe6Ge6-type structure (space group P6/mmm) with a = 5.5461 Angstrom, c = 9.0477 A and V = 241 Angstrom(3). This compound shows ferrimagnetic behaviour with the ordering temperature T-c = 421 K. A peak is also observed in the thermal magnetic curve at 330 K. Under magnetic fields of 100, 300 and 400 Oe, the magnetization values first increase with increasing temperature, next exhibit a peak and then decrease with further increase in temperature. When the applied magnetic field is sufficiently large, e.g. 1000 and 2100 Oe, the magnetization of the whole sample decreases with increasing temperature. With increasing temperature from the range 77-300 K, the coercivity first increases, next undergoes a peak at about 200 K and then decreases. At room temperature a magnetization jump is observed in the magnetization curves at a field of about 4 kOe in both the aligned and the free powder samples. This jump may be attributed to the spin-flop or metamagnetic transition. The magnetic anisotropy field at room temperature is found to be 8.33 kOe.

We have studied random as well as field-aligned powders of (Sm1−xPrx)2Fe17 and their nitrides (0≤x≤1.0), to investigate, by Pr substitution for Sm, the effects on the Curie temperature, saturation magnetization, anisotropy field and hyperfine interaction parameters. Pr substitution for Sm causes the Curie temperature and anisotropy field to decrease monotonously, but it has the opposite effect in the saturation magnetization. The concentration dependence of the magnetic hyperfine fields of (Sm1−xPrx)2Fe17Ny and their parent compounds for different iron sites are given. As the P content x exceeds 0.6, the spin reorientation takes place, which has been confirmed by aligned powder X-ray diffraction as well as Mossbauer fitting results.

In a systematic study of the Sm 10 Fe 85 Ti x (4.7 x 3 (Fe, Ti) 29 compound has been found to be a new phase, of which the structure is Nd 3 (Fe, Ti) 29 -type. The X-ray diffraction pattern of Sm 3 (Fe 0.933Ti 0.06 7) 29 can be indexed on the monoclinic symmetry with the lattice parameters a = 1.065 nm, b = 0.858 nm, c = 0.972 nm and β = 96.98°. The Sm 3 (Fe 0.933 Ti 0.067 ) 29 compound exhibits ferromagnetic ordering with a Curie temperature T C = 486 K. The saturation magnetization M S is 125 A m 2 /kg at 77 K and 119 A m 2 /kg at room temperature. The room temperature anisotropy field is 3.4 T.

The field dependence of the coercive field for isotropic and aligned Sm2Fe17Nx epoxy resin bonded magnets are investigated. Results indicate that the coercive field of the isotropic magnet is larger than that of the aligned magnet. For small magnetizing fields, the coercive field of the sample magnetized antiparallel to the alignment direction is larger than that of the sample magnetized parallel to the alignment direction of the magnets. When the magnetizing field is large enough, the coercivities obtained after magnetizing the aligned sample in parallel and antiparallel directions are the same. The microstructural parameter derived from the temperature dependence of the coercive field implies that both nucleation and pinning mechanism could be responsible for the magnetic hardening of the Sm2Fe17Nx epoxy resin bonded magnets.

The hard magnetic properties of a new interstitial nitride Sm3(Fe0.933Ti0.067)29Ny (y approximately 5) have been investigated by ball milling. The saturation magnetization linearly decreases with ball-milling time. By ball milling, maxima of remanence Br=1.04 T, intrinsic coercivity mu 0iHc=0.83 T and energy product (BH)max=105 W m-3 are achieved at 293 K.

Positive and negative interaction have been found to co-exist in Sm2Fe17Nx and Nd2Fe14B isotropic magnets. The measured positive interaction may come from the interactions from those grains with small deviation angle between its easy axis and the direction of external field, whereas the negative interaction may come from those grains with large deviation angle. The numerical calculations of the magnetostatic fields around a particle indicate that the positive interaction results from the magnetostatic interaction among nearest-particles located in forefront and backfront along their common easy axis of magnetizations and the negative interaction results from the magnetostatic interaction among those particles located in same plane perpendicular to their easy axis of magnetizations. In soft-hard multiphase materials, larger the remanence enhancement is, stronger the negative interparticle interaction becomes. The remanence enhancement in SmFeN materials have also been investigated.

The structural and magnetic properties of the R(2)Fe(16)SiC(2) (R = Y, Sm, Gd, Tb, Dy, Ho, Er and Tm) compounds have been investigated. These carbides were prepared by the arc-melting method and found to crystallize in the rhombohedral Th2Zn17-type structure. The substitution of Si for Fe in the R(2)Fe(17)C(2) compounds is able to stabilize the structure of the 2:17-type carbides although it results in small decreases in saturation magnetization and Curie temperature. The Sm2Fe16SiC2 compound is found to have a uniaxial magnetocrystalline anisotropy and shows a roam-temperature anisotropy field of about 110 kOe. Spin-reorientation transitions are observed in the Er2Fe16SiC2 and Tm2Fe16SiC2 compounds. The replacement of Fe by Si in the R(2)Fe(17)C(2) compounds increases the uniaxial anisotropy of the R sublattice, resulting in the increase in spin-reorientation temperature.

In the present work, hard magnetic behaviours of (Sm1-yPry)2Fe17Nx magnets are investigated. Remanence enhancement is observed when some of the Sm atoms are replaced by Pr atoms in the compounds, which is due to the larger saturation magnetization of (Sm1-yPry)2Fe17Nx than of pure Sm2Fe17Nx. Meanwhile the coercivity of (Sm1-yPry)2Fe17Nx decreases with increasing Pr content in the compounds, which corresponds to the decrease of the anisotropy field in the compounds. In order to obtain a combined good effect on the remanence and the coercivity, the Pr content y should be no more than 0.4 in (Sm1-yPry)2Fe17Nx nitrides.

The coercivity of the Sm3(Fe,Ti)29Ny nitride is controlled by the nucleation mechanism. The phenomenon of a minimum of the coercivity in the angular dependence of the coercivity is found for the Sm3(Fe,Ti)29Ny nitride. The small magnetizing field required to obtain the saturation coercivity and the small interparticle interaction for the isotropic Sm3(Fe, Ti)29Ny magnet imply that grains of Sm3(Fe, Ti)29Ny are well isolated.

By means of x‐ray phase analysis, it is shown that all the interstitial Sm2(Fe1−xAlx)17Ny nitrides and the parent compounds crystallize in Th2Zn17‐type structure for x≤0.4. The lattice constants of the parent compounds increase linearly with Al concentration. The introduction of nitrogen leads to a further increase in lattice constants, but the amplitude of the increase decreases with increasing Al concentration. The introduction of nitrogen leads to an increase of Curie temperature Tc . The composition dependence of Tc of the parent compounds exhibits a maximum, whereas Tc of the nitride decreases monotonously with increasing Al concentration from 750 K for x=0 to 313 K for x=0.4. The mean magnetic moments of iron ions in both nitrides and parents decrease monotonously with increasing Al concentration.

Magnetocrystalline anisotropy, Curie temperatures, spin reorientation temperatures, and first‐order magnetization processes (FOMP) are reported for RFe10Si2 compounds with R=Y, Gd, Tb, Dy, Ho, Er, and Lu. The saturation magnetizations of them at 1.5 K are determined. The value of the R‐Fe magnetic‐coupling constant JRFe/k, derived by a mean‐field analysis of the Curie temperatures, is about −10 K. A tentative spin‐phase diagram for the RFe10Si2 series is presented.

In China there are several laboratories which have pulsed magnetic fields up to 30–40 T. A study of 50 T pulsed magnets has been carried out. A hybrid-magnet project to obtain steady fields up to 20 T is also being carried out. In various laboratories, research on high-field magnetization processes, anistropy of rare-earth compounds, magnetophonon resonance of two-dimensional electron systems and the high-field properties of superconducting materials is performed.

The structure and magnetocrystalline anisotropy of SmMo2Fe10 alloy were investigated. X-ray analysis revealed that SmMo2Fe10 has the tetragonal ThMn12 structure with parameters a = 8.6015 A , c = 4.7996 A , v = 355 A 3 . SmMo2Fe10 has an easy axis [001] from 78 to 293 k. The temperature dependence of the magnetization was measured. The Curie temperature was found to be 463 K. The temperature dependence of magnetic anisotropy field in the range 77 k – 300 k was determined. The value of magnetic anisotropy field at 300k is 45 kOe. It shows that SmMo2Fe10 based alloys can serve as permanent magnet materials.