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Nd-Fe-B-based alloys as sintered Nd2Fe14B-typed permanent magnets have been studied extensively due to their excellent magnetic properties. In this work, the experimental information on the corresponding phase equilibria of the Nd-Fe-B ternary system in the published literature is reviewed first. The key Nd-Fe-B alloys annealed at 873 and 1073 K were then investigated experimentally to determine the phase equilibria of the system using x-ray diffraction technique and scanning electron microscope (SEM) with energy dispersive spectrometry (EDS). The ternary intermetallic compound, Nd2Fe14B with space group P42/mnm as Nd2Fe14B structure type, NdFe4B4 with space group Pccn as REl.11Fe4B4 structure type and Nd5Fe2B6 with space group R $$ \overline{3} $$ m as Pr5Co2B6 structure type were confirmed at 873 and 1073 K. The binary intermetallic compound Nd5Fe17 is stable at 873 K, while it was not found at 1073 K. The phase equilibria of the Nd-Fe-B ternary system consists of 14 single-phase regions, 28 two-phase regions and 16 three-phase regions at 873 K, while there are 8 single-phase regions, 14 two-phase regions and 7 three-phase regions at 1073 K except for the B-rich part.

The solidification microstructure and phase transition of ten La-Nd-Fe alloys were studied experimentally by scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) and differential thermal analysis (DTA). Phase compositions and phase transition temperatures of La-Nd-Fe alloys were measured and the formed phases were identified. The solidification behavior of La-Nd-Fe alloys was analyzed based on the experimental results of both solidification microstructure and phase transitions with the reported Nd-Fe, La-Fe and La-Nd sub-binary phase diagrams. The results indicated that the solidification processes of all La-Nd-Fe alloys begin with the precipitation of primary phase fcc(γ-Fe) and then follow by the formation of bcc(α-Fe) and/or Fe17Nd2 phases through different peritectic reactions. The solidification microstructure of three Fe65La29Nd6, Fe65La25Nd10 and Fe65La22Nd13 alloys presents three-phase microstructure with bcc(α-Fe), Fe17Nd2 and fcc(La,Nd) phases, while that of three Fe65La19Nd16, Fe65La9Nd26 and Fe65La15.5Nd19.5 alloys shows three-phase microstructure with bcc(α-Fe), Fe17Nd2 and dhcp(La,Nd) phases. The two-phase micorstructure with Fe17Nd2 and dhcp(La,Nd) ohases was formed in the solidification microstructure of four Fe65La12Nd23, Fe65La6.5Nd28.5, Fe65La4Nd31 and Fe65La1.5Nd33.5 alloys. Moreover, no stable ternary intermetallic compound was found in the present experiments. The solidification microstructure and phase transition of La-Nd-Fe alloys would provide a basis for the design of La-Nd-Fe-B magnetic alloys.

The phase formation of the (Nd0.70Pr0.30−xCex)2.28Fe13.58B1.14 (x = 0.10, 0.15, and 0.20; hereafter defined as Pr20Ce10, Pr15Ce15 and Pr10Ce20, respectively) and (Nd0.60Pr0.40−yCey)2.28Fe13.58B1.14 (y = 0.10, 0.20, and 0.30; hereafter defined as Pr30Ce10, Pr20Ce20 and Pr10Ce30, respectively) alloys that were prepared via the arc-melting method was investigated experimentally. The x-ray diffraction results revealed that all alloys annealed at 1173 K for 360 h consisted of a (NdPrCe)2Fe14B main phase with a tetragonal Nd2Fe14B-typed structure (space group P42/mnm) and an α-Fe minor phase, except for the Pr10Ce30 alloy, which contained an additional CeFe2 phase. The magnetic properties of the (Nd0.70Pr0.30−xCex)2.28Fe13.58B1.14 and (Nd0.60Pr0.40−yCey)2.28Fe13.58B1.14 ribbons that were prepared by melt spinning were examined. The remanence (Br) and maximum magnetic energy product ((BH)max) of the (Nd0.70Pr0.30−xCex)2.28Fe13.58B1.14 ribbons increased first and then decreased, whereas the coercivity (Hcj) of the ribbons increased with an increase in Ce content. The Br and (BH)max of the (Nd0.60Pr0.60−yCey)2.28Fe13.58B1.14 ribbons increased, whereas the Hcj of the ribbons decreased gradually with an increase in Ce content. This changed behavior of magnetic properties is attributed to the variation of volume fraction of the α-Fe phase and different phase formations in the melt-spun ribbons. The Curie temperatures (Tc) of all ribbons decreased slightly with Ce substitution, which results from the lower Curie temperatures of Pr2Fe14B and Ce2Fe14B. The Pr10Ce30 ribbon with a higher Ce content exhibited optimal magnetic properties (Br = 9.71 kGs, Hcj = 13.09 kOe, (BH)max = 18.78 MGOe), which indicates that suitable magnetic properties of the Nd–Pr–Ce–Fe–B melt-spun ribbons can be achieved by alloy-composition and phase-formation design.

The phase relations in the pseudo-binary Nd2Fe14B–Pr2Fe14B system were investigated and constructed by means of X-ray powder diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). The results revealed that similar to the end-members of the Nd2Fe14B–Pr2Fe14B system form a continuous solid solutions, all intermediate (Nd1−xPrx)2Fe14B samples belong to tetragonal Nd2Fe14B-type structure (space group P42/mnm). The lattice parameter a almost remains the same, and the lattice parameter c and unit-cell volume V increase linearly with an increase of Pr concentration. Based on the results of DTA measurements and X-ray powder diffraction examinations, the tentative phase diagram of the Nd2Fe14B–Pr2Fe14B isopleth has been constructed.

The series of polycrystalline Bi 1− x La x FeO 3 (0 ⩽ x ⩽ 0.50) ceramic powders was successfully synthesized by sol–gel method in this paper. X-ray diffraction and Rietveld crystal structure refinement software (FULLPROF) were used as complementary method to study structure and hyperfine interactions of the samples. It was a clear indication of structural modification and symmetry changes brought about by La doping. The BFO is crystallized in rhombohedrally distorted perovskite structure with space group R3c for x ⩽ 0.10. With an increase of La content, within the range x = 0.10–0.20 a structural phase evolutes from rhombohedral to cubic Pm 3 ¯ m structure, and then transits to orthorhombic Pbnm structure on further increasing the La-doping to x = 0.50. The magnetization of La-doped samples is improved with the increase of La content. The coercive field (Hc) increases remarkably with an increase in La doping and x = 0.50 exhibits the highest Hc (20.2 kOe at room temperature) reported so far in any rare earth doped BFO, which will have a great potential for practical application in non-volatile memory devices. Moreover, high-field magnetization and remanence (Mr) increase with La doping content due to the gradual change in spin cycloid structure.

The effect of temperature on the overall electrochemical properties of LaNi 4.5 Co 0.25 Al 0.25 hydrogen storage alloy has been studied systematically. The results show that temperature has a striking effect on the overall electrochemical properties. The LaNi 4.5 Co 0.25 Aln 0.25 alloy electrode has a maximum capacity of 324.4 mA h/g at 253 K after first activation at room temperature. The cycling stability and capacity retention S 50 increase with the decreasing temperature from 333 K to 253 K, while the reversible capacity loss (RCL) and irreversible capacity loss (ICL) both increase with elevation of testing temperature. The high-rate discharge ability (HRD) at room temperature is superior to that of other temperatures.

Crystal structure of the compounds Co40V60−2xLax has been investigated by means of X-ray powder diffraction (XRD). The compounds crystallize in the tetragonal σ phase structure with the space group P42/mnm and form a solid solution with a solubility limit of x = 9.52. The lattice parameters a, c and the unit cell volume V of the compounds decrease linearly with the La content. A structure model with a preferential substitution of La for V atoms on the 8j sites accompanied by the presence of vacancies on these sites is proposed for Co40V44La8. The proposal structure model gives a satisfactory fitting to the XRD data and a reasonable La content close to the nominal composition as well as a coincidence of the calculated density with the experimentally measured one. The preferential occupation of La atoms on the 8j site is discussed based on a consideration of geometric constrain and thermodynamics.

The phase relations of the ternary system Ce-Al-Cu in the Cu-poor part at 503 K were investigated by X-ray powder diffraction (XRD). The investigated composition region consists of 16 single-phase, 32 two-phase and 17 three-phase regions. At 503 K, the maximum solid solubilities of Cu in Al, alpha-Ce(3)Al(11), CeAl(3) and CeAl(2) are about 2.5 at.%, 1.6, 3.6 and 5.3, respectively, and Al in CeCu(5) is about 39.2 at.% The homogeneity ranges of Al(2)Cu and AlCu phases extend from about 32.1 to 32.6 at.% Cu and 49.7 to 52.4 at.% Cu, respectively. Five ternary compounds and their solid solutions have been observed in this work: CeAl(12-x)Cu(x) (4.0

A series of polyaniline (PANI) films were prepared on quartz substrates by in situ polymerization with different reaction time under 450 MPa of hydrostatic high pressure. For investigating the effect of high pressure on the growth of the films, two additional series of samples with comparable conditions under ambient pressure were synthesize. The aniline cation radicals nucleated within 2 min and the polyaniline films grew within 10 min at 450 MPa of pressure. This compared with about 10 min for nucleation and 60 min for growth of polyaniline films under comparable ambient conditions. The process of PANI film growth under high pressure was obviously different from that in ambient pressure case. The high pressure used in polymerization affected directly the electrical property, the morphology, and growth of the films. A formation model of polyaniline film growth in high pressure case was proposed.

According to the elemental ratio of Nd:Mg:Ni = 1:1:4, NdMgNi 4 ternary alloy was synthesized by sintering pressed tablets of the powders milled for 6 h. The sintering conditions are: 673 K, 3 h → 873 K, 3 h → 973 K, 3 h. The XRD analysis shows that the REMgNi 4 (RE = La, Ce, Pr, Nd) alloys are single component alloys, and that Mg 2 Ni exists during the process of formation of the alloys. The electrode properties of the REMgNi 4 alloys were measured by simulated battery test. It was found that the initial discharge capacity of Mg 2 Ni and LaMgNi 4 alloys milled for 50 h is about 400 mAh/g, but a good cycle life has been observed for the electrode of milled LaMgNi 4 alloy. As to REMgNi 4 alloys, a slightly increasing discharge capacity was observed in the following order: LaMgNi 4 > NdMgNi 4 > CeMgNi 4 > PrMgNi 4 .

A series of Mg 2− x Nd x Ni ( x =0.05, 0.1, 0.2, 0.3) and Mg 1.95 RE 0.05 Ni (RE=La, Ce, Pr, Nd, Y) ternary alloys were prepared by ball milling of mixed powder of Mg, Ni, RE and sintering under pure argon. XRD analysis shows that Mg 2− x Nd x Ni ( x =0.05, 0.1) and Mg 1.95 RE 0.05 Ni alloys are all single-phase with the same crystal structure as Mg 2 Ni while three phases (including Mg 2 Ni, NdNi and NdMgNi 4 ) were formed in Mg 1.8 Nd 0.2 Ni and Mg 1.7 Nd 0.3 Ni alloys. The lattice constants ( a , c , c / a ) of Mg 2 Ni phase in these ternary alloys were calculated. Calculated values of a and c are strongly influenced by elemental substitution, while no different changes were observed in a / c . The electrochemical characteristics of the alloys were evaluated by simulated battery test. It is found that the initial discharge capacity of Mg 2− x Nd x Ni alloy milled for 10 h was obviously improved with increasing Nd content. A good cycle life was also observed in the Mg 1.7 Nd 0.3 Ni alloy electrode. It is suggested that combined effects contribute to the enhancement in electrochemical characteristics, the presence of NdMgNi 4 being beneficial for the improvement in cycle life of Mg 2− x Nd x Ni ( x =0.2, 0.3), especially for the Mg 1.7 Nd 0.3 Ni alloy electrode. As to Mg 2− x RE x Ni alloys, the effectiveness in improving the discharge capacity increased in the following order: Pr>Nd>Ce>La>Y.

The isothermal section of the Ho–Fe–Cr ternary system was investigated by means of X-ray powder diffraction (XRD), metallography and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). The ternary compound HoFe 12− x Cr x ( x = 2) was characterized and the homogeneity range of the various ternary solutions was studied. It crystallizes with ThMn 12 -type structure, space group I 4/ mmm and unit parameters a = 0.8406 nm and c = 0.4756 nm. The homogeneity range in HoFe 12− x Cr x was determined as x = 1.9–3.6, i.e. 14.6–27.7 at.% Cr. The maximum solid solubilities of Cr in Fe, Ho 2 Fe 17 , Ho 6 Fe 23 , HoFe 3 and HoFe 2 are about 28.0 at.%, 4.0 at.%, 13.0 at. %, 3.0 at.% and 11.0 at.%, respectively.

The 773 K isothermal section of the phase diagram of Nd–Ni–V ternary system was investigated by X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. There are in total 14 single-phase regions, 25 two-phase regions and 12 three-phase regions in the 773 K isothermal section. The maximum solid solubilities of V in Ni, NdNi 5 , Nd 2 Ni 7 and NdNi 2 , is about 16.5 at.% V, 2.0 at.% V, 1.0 at.% V and 3.0 at.% V at 773 K, respectively, and that of Nd in Ni, Ni 3 V, Ni 2 V, Ni 2 V 3 , NiV 3 and V does not exceed 1 at.% Nd. No ternary compounds have been observed in this work.

The isothermal section of the phase diagram of the Pr-Ni-V ternary system at 500 °C was investigated by X-ray diffraction (XRD), differential thermal analysis (DTA) and optical microanalysis techniques. In the isothermal section, there are 14 single-phase regions, 25 two-phase regions and 12 three-phase regions. No ternary compounds were observed in this system. At 500 °C, the maximum solid solubility of V in Ni, PrNi 5 , Pr 2 Ni 7 , PrNi 3 and PrNi 2 , is about 17, 3, 1.5, 1.5 and 4 at.%, respectively. The homogeneity range of Ni 3 V, Ni 2 V, Ni 2 V 3 and NiV 3 extend from about 21 to 27 at.%, 33.5 to 34.5 at.%, 58.5 to 74 at.% and 77.5 to 78.5 at.% V, respectively.