The crystal structure and phase relations of the Pr2Fe14B-La2Fe14B system were investigated by X-ray powder diffraction （XRD）, differential scanning calorimetry （DSC） and scanning electron microscopy （SEM） equipped with energy dispersive X-ray spectroscopy （EDS）. The crystal structure parameters were determined by full-profile Rietveld refinements. The results revealed that all alloys of （Pr1–xLax）2Fe14B crystallized the Nd2Fe14B-type structure with the space groupP42/mnm and formed a continuous solid solutions betweenx=0.0 and 1.0. The lattice parametera,c, unit-cell volumeVand c/a ratio increased linearly with the La concentra-tion. Determined by thermogravimetry analysis, the Curie temperature （TC）, phase transition temperature and melting temperature of （Pr1–xLax）2Fe14B decreased linearly upon the La content. Based on the results of DSC measurements and X-ray powder diffraction examinations, the phase diagram of the Pr2Fe14B-La2Fe14B system was built up.
The powders of RE2Co17（RE=Y, Ce, Nd, Ho, Er） and Ho x Co100–x（x=6, 8, 10, 12） alloys were prepared by the arc melting method and high-energy ball mill process. The compositions and morphologies of the alloys were characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）, and the microwave absorbing properties were studied by a vector network analyzer. The results showed that the alloy of Y2Co17 had better absorbing properties at low frequencies and its lowest reflectivity value was –9.5 d B at 3.8 GHz. The lowest reflectivity value of Ho2Co17 alloy was –13.7 d B at 7.02 GHz and it obtained large absorbing bandwidth. Reflectivity value less than –5 d B was from 5.1 to 10.2 GHz. When x=6 and x=8, the alloys of Ho x Co100–x consisted of Ho2Co17 phase and Co phase. They had good radar absorbing properties. With increase in Ho content, the minimum reflectivity value worsened and the absorbing peak frequency shifted toward higher frequencies. But when x=12, the absorbing peak frequency shifted toward lower frequencies but the minimum reflectivity value worsened.
The effect of rapid solidification on structure and electrochemical performance of the LaNi4.5Co0.25Al0.25 hydrogen storage alloy was investigated by X-ray powder diffraction and a simulated battery test, including maximum capacity, cycling stability, self-discharge, and high-rate discharge ability （HRD）. All the melt-spun alloys were single-phase with the CaCu5-type structure （space groupP6/mmm）. In comparison to the as-cast alloy, the rapidly quenched alloys manifested an improved homogeneity of com-position and expanded lattice parameters. The electrochemical measurements showed that the activation property, cycling stability and self-discharge of the alloy electrodes were also improved for the rapid solidified alloys. The HRDof the as-cast alloy was better than those of all the rapidly solidified alloys. As the quenching rate increased, the HRD and exchange current density first decreased and then increased.
The isothermal section of the phase diagram of the Gd-Sm-Co ternary system at 773 K was investigated by X-ray powder diffraction （XRD）, differential thermal analysis （DTA）, optical microscopy and scanning electron microscopy （SEM） techniques. The result shows that the isothermal section consists of 12 single-phase regions, 16 two-phase regions and 5 three-phase regions. Five pairs of corresponding compounds of Gd-Co and Sin-Co systems, i.e., Gd2Co17 and Sm2Co^7, Gd2Co7 and Sm2Co7, GdCo3 and SmC03, GdCo： and SmCo：, Gd3Co and Sm3Co form continuous series of solid solutions. The maximum solid solubility of Sm in Gd4Co3 arid Gdl2Co7 were about 7.2 at.% and 47.8 at.% Sm, respectively. The maximum solid solubility of Gd in Sm5Col9 and SmsCo2 were about 4.7 at.% and 7.6 at.% Gd, respectively. The binary compounds Sm9Co4, GdCos and SmCo5 were not observed at 773 K. No ternary compound was found.
The nano-crystalline La_（0.1）Bi_（0.9）FeO_3 compound was successfully synthesized by starch-based combustion method. The crystal structure and magnetic behavior were studied by temperature-dependent X-ray diffraction（XRD）, scanning electron microscopy（SEM）, differential scanning calorimetry（DSC） and magnetic measurements. The La_（0.1）Bi_（0.9）FeO_3 compounds crystallized in a rhombohedrally distorted perovskite structure with space group R3 c. The substitution of La for Bi reduced the rhombohedral distortion. The structural phase transitions in La_（0.1）Bi_（0.9）FeO_3 driven by temperature showed that the extraordinary two-phase coexistence state of BiF eO 3 and LaF eO 3 was observed in a narrow temperature range of 630–700 oC. The magnetization of the La_（0.1）Bi_（0.9）FeO_3 sample was improved by heat treatment in the temperature range. When the heat treatment temperatures rose from 25 to 600 oC, the remanence（Mr） and coercivity（Hc） of the La_（0.1）Bi_（0.9）FeO_3 compound almost remained the same, and increased rapidly to 0.134 emu/g and 7.1 KOe on further increasing the heat treatment temperature to 650 oC.
In order to improve the microwave absorbing properties of NdFeB alloys, as-jet milled powders were further processed in a planetary mill. The phase structure, morphology and particle size of the alloy powders were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and laser diffraction-based particle size analyzer, respectively. The saturation magnetization and electromagnetic parameters of the powders were determined by a vibrating sample magnetometer （VSM） and a vector network ana-lyzer （VNA）, respectively. The results showed that the saturation magnetization decreased as the milling time increased. The mini-mum absorption peak frequency shifted towards the lower region and the reflection loss values increased with increasing the ball mill-ing time. The minimum absorption peak value of the powders milled for 15 h on the basis of jet milling reached–44.4 dB at 11.04 GHz, and the bandwidth of R〈–10 dB was 1.2 GHz with the best matching thickness of 1.8 mm.
