Synthesis, Crystal Structure, Fluorescence, Thermal Stability and Magnetic Properties of the Dinuclear Manganese(Ⅱ) Complex [Mn_2(L)_2(2,2'-bipy)_2(H_2O)_5]_2·3H_2O

A new dinuclear manganese complex [Mn2（L）2（2,2＇-bipy）2（H2O）512·3H2O has been synthesized with MnSO4·H2O, 2,2＇-bibenzoic acid （H2L） and 2,2＇-bipyridine（2,2＇-bipy） in the mixed solvent ethanol and water. It crystallizes in monoclinic, space group Pi with a = 9.9944（10）, b = 21.939（2）, c = 25.628（3） A, a = 108.429（3）, β = 100.613（4）, 7 = 102.821（3）°, V = 4997.9（9） A3, Dc= 1.355 g/cm^3, Z = 2, F（000） = 2108, GOOF = 1.074, the R= 0.0626 and wR= 0.1531. The structure of the complex contains two [Mn2（L）2（2,2＇-bipy）2] units, ten coordinated H2O molecules and three uncoordinated H2O molecules. The fluorescence, thermal stability and magnetic properties of the complex were investigated.

Hydrothermal Synthesis, Crystal Structure, Thermal Stability and Magnetic Properties of a Dinuclear Copper(Ⅱ) Complex

A new dinuclear copper（Ⅱ） complex [Cu（CH3COO）（C7H5N4）（H2O）]2·3.5H2 O has been hydrothermally synthesized with copper acetate, o-acetamidobenzoic acid and 3-（pyridin-2-yl）-1,2,4-triazole. It crystallizes in the monoclinic space group P21/c, with a = 12.0188（7）, b = 13.7993（8）, c = 8.7488（5） A, β = 101.7350（10）o, V = 1420.67（14） A3, D3 c = 1.568 g/cm, Z = 1, F（000） = 690, the final GOOF = 1.145, R = 0.0437, and w R = 0.1097. The crystal structure shows that the whole molecule consists of two copper ions bridged by two μ2-η1：η0 3-（pyridin-2-yl）-1,2,4-triazole anions. The coordination environment of Cu（Ⅱ） ion is Cu O2N3, giving a distorted square pyramidal geometry. The thermal stability and magnetic properties of the complex were investigated.

Effects of terbium sulfide addition on magnetic properties,microstructure and thermal stability of sintered Nd-Fe--B magnets

To increase coercivity and thermal stability of sintered Nd–Fe–B magnets for high-temperature applications, a novel terbium sulfide powder is added into（Pr（0.25）Nd（0.75））（30.6）Cu（0.15）Fe（bal）B1（wt.%） basic magnets. The effects of the addition of terbium sulfide on magnetic properties, microstructure, and thermal stability of sintered Nd–Fe–B magnets are investigated.The experimental results show that by adding 3 wt.% Tb2S3, the coercivity of the magnet is remarkably increased by about 54% without a considerable reduction in remanence and maximum energy product. By means of the electron probe microanalyzer（EPMA） technology, it is observed that Tb is mainly present in the outer region of 2：14：1 matrix grains and forms a well-developed Tb-shell phase, resulting in enhancement of HA, which accounts for the coercivity enhancement.Moreover, compared with Tb2S3-free magnets, the reversible temperature coefficients of remanence（α） and coercivity（β） and the irreversible flux loss of magnetic flow（hirr） values of Tb2S3-added magnets are improved, indicating that the thermal stability of the magnets is also effectively improved.

Magnetic Properties and Thermal Stability of Pr_(1-x)La_xCo_(5-y)Alloys

Pr1-xLaxCo5-y (x=0, 0.15. 0.25, 0.35,1.0, y=0.5, 0.7, 0.9, 1.0) alloys were investigated. The effect of the variation of x and y on magnetic properties and thermal stability of the alloys were studied. The magnetic properties for the Pr0.85La0.15Co4.3 and Pr0.75La0.25Co4.1 magnets are iHc=368 kA/m, Br=0.91 T, (BH)max=145.6 kJ/m3, αBr=-0.03%/℃ and iHc=568 kA/m,Br=0.8 T, (BH)max=127.2 kJ/m3,αBr,=-0.06%/℃, respectively The phase structures of as-cast alloys and magnets were investigated

Thermodynamic behaviour of Rashba quantum dot in the presence of magnetic field

The thermodynamic properties of an In Sb quantum dot have been investigated in the presence of Rashba spin–orbit interaction and a static magnetic field. The energy spectrum and wave-functions for the system are obtained by solving the Schrodinger wave-equation analytically. These energy levels are employed to calculate the specific heat, entropy,magnetization and susceptibility of the quantum dot system using canonical formalism. It is observed that the system is susceptible to maximum heat absorption at a particular value of magnetic field which depends on the Rashba coupling parameter as well as the temperature. The variation of specific heat shows a Schottky-like anomaly in the low temperature limit and rapidly converges to the value of 2kB with the further increase in temperature. The entropy of the quantum dot is found to be inversely proportional to the magnetic field but has a direct variation with temperature. The substantial effect of Rashba spin–orbit interaction on the magnetic properties of quantum dot is observed at low values of magnetic field and temperature.

Controllable hydrothermal synthesis of star-shaped Sr3Fe2（OH）12 assemblies and their thermal decomposition and magnetic properties

Pure phase star-shaped hydrogarnet Sr3Fe2（OH）12 assemblies were synthesized by a mild hydrothermal method （210℃, 12 h）, and the effects of the preparation conditions on the phase composition of the product were investigated. It was found that the impurity phases could be decreased or eliminated by increasing the molar ratio of Sr2＋ to Fe3＋, and that high temperatures favored the formation of Sr3 Fe2（OH）12 and reduced the concentration of CO32- -containing byproducts. The thermal decomposition of the star-shaped Sr3Fe2（OH）12 assemblies was examined, and the results showed that the dehydration process at higher temperatures is accompanied by the formation of SrFeO3-δ. Above 655 ℃, a solid state reaction between the SrFeO3-δ and Sr（OH）2 or SrCO3 results in the formation of Sr4Fe3O10-δ.The mag- netic properties of the as-synthesized Sr3Fe2（OH）12 and of samples calcined at different temperatures were assessed. A sample calcined at 575 ℃ exhibited greatly enhanced ferromagnetic properties, with a remanent magnetization of 1.28 emu/g and a coercivity of 4522.1 Oe at room temperature.

Structure, magnetic properties, and thermal stability of Sm(1-x)Tm_xCo_5compounds

Structure, magnetic properties, and thermal stability of ternary Sm1-xTmxCo5 compounds were studied via X-ray diffraction（XRD）, thermal magnetic analysis（TMA）, and magnetic measurements. XRD results show that all the compounds have a main phase of hexagonal CaCu5-type crystal structure with small amount of impurity phases; increasing Tm content is associated with contraction of the hexagonal unit cell in the direction of the c axis and expansion of the a and b parameters. TMA results indicate that the Curie temperature（TC） of Sm1-xTmxCo5 compounds gets higher with the increase in Tm content.Magnetic measurements show that both the magnetic anisotropy field（HA） and the magnetization at an applied field of 7 T（M7 T） decrease with the increase of Tm content. However, the thermal stability of both the HAand M7 Tof all the Tm doped compounds is remarkably improved compared with that of the pure SmCo5 compound, leading to the result that both the M7 Tand HAof Sm0.8Tm0.2Co5 .2are higher than those of SmCo5 compound at 473 K, which indicates the good potential of Tm doped compound in the practical applications at elevated temperature.

Effect of niobium substitution on microstructures and thermal stability of TbCu7-type Sm-Fe-N magnets

This paper reports crystal structures, magnetic properties and thermal stability of TbCu7-type Sm（8.5）Fe（（85.8-x）Co（4.5）Zr（1.2）Nbx（x = 0-1.8） melt-spun compounds and their nitrides, investigated by means of X-ray diffraction, vibrating sample magnetometer, flux meter and transmission electron microscope. It is found that the lattice parameter ratio c/a of TbCu7-type crystal structure increases with Nb substitution, which indicates that the Nb can increase the stability of the metastable phase in the Sm-Fe ribbons. Nb substitution impedes the formation of magnetic soft phase a-Fe in which reversed domains initially form during the magnetization reversal process. Meanwhile, Nb substitution refines grains and leads to homogeneous micro structure with augmented grain boundaries. Thus the exchange coupling pining field is enhanced and irreversible domain wall propagation gets suppressed. As a result, the magnetic properties are improved and the irreversible flux loss of magnets is notably decreased. A maximum value 771.7 kA/m of the intrinsic coercivity H（cj） is achieved in the 1.2 at% substituted samples.The irreversible flux loss for 2 h exposure at 120 ℃ declines from 8.26% for Nb-free magnets to 6.32% for magnets with 1.2 at% Nb substitution.

Physico-chemical properties of 3-methoxy-2-nitrobenzoates of some rare earth elements(Ⅲ)

The complexes of 3-methoxy-2-nitrobenzoates of Pr（Ⅲ）, Nd（Ⅲ）, Sm（Ⅲ）, Eu（Ⅲ）, Gd（Ⅲ）, Tb（Ⅲ）, Er（Ⅲ） and Tm（Ⅲ） with the formula： Ln（C8H6NO5）3·2H2O, where Ln=lanthanides（Ⅲ）, were synthesized and characterized by elemental analysis, Forier transform irtrared （FTIR） spectroscopy, magnetic and thermogravimetric studies and also by X-ray diffraction （XRD） measurements. The complexes had col- ours typical for Ln（Ⅲ） ions. The carboxylate groups bound as bidentate chelating. On heating to 1173 K in air they decomposed in the same way, at first, dehydrated in one step to anhydrous salts, and then decomposed to the oxides of respective metals with intermediate formation of the oxycarbonates. The enthalpy values of the dehydration process changed from 133.72 to 44.50 kJ/mol. Their solubility in water at 293 K was of the order of 10-4 mol/dm3. The magnetic moments of analysed complexes were determined by Gouy＇s method in the range of 76-303 K.

Micron-scale 1:5H-based precipitated phase with the lamellar structure of sintered Sm_(2)Co_(17)-based magnets and its potential application

The excellent thermal stability of magnetic properties of Sm_(2)Co_(17)-based magnets is their most impor-tant feature.However,this stability is reduced when the maximum energy product of Sm_(2)Co_(17)-based magnets is improved,which is mainly determined by the Fe/Cu distribution of the 2:17R cell and 1:5H cell boundary phases.During the demagnetization process,the Cu-rich 1:5H cell boundary phase with a width of 2-15 nm obstructs the motion of the domain walls,yielding coercivity.Herein,we report a micron-scale Cu/Zr-rich and Fe-lean 1:5H-based precipitated phase with a lamellar structure,probably induced by Sm_(2)O_(3) doping.This structure enables the separate regulation of Fe and Cu distribution for Sm_(2)Co_(17)-based magnets with Fe-rich 2:17R cell phases and Cu-rich 1:5H cell boundary phases,consid-erably optimizing the thermal stability of magnetic properties.This discovery can be further developed to produce Sm_(2)Co_(17)-based magnets with high performance and excellent thermal stability of magnetic properties.