共查询到20条相似文献,搜索用时 31 毫秒
1.
Daijitsu HaradaYukio Hinatsu 《Journal of solid state chemistry》2002,164(1):163-168
Magnetic and calorimetric properties of Ln3RuO7 (Ln=Pr, Gd) have been investigated. Magnetic susceptibility and specific heat measurements indicate that both Pr3RuO7 and Gd3RuO7 compounds show magnetic transitions at 55 K and 15 K, respectively. In addition, a clear structural phase transition has been found at 382 K for Gd3RuO7 from the specific heat measurements. From the temperature dependence of the magnetic specific heat, the magnetic entropy change is estimated and the magnetic ground states of each ion are determined. 相似文献
2.
Hiroaki Nishimine Makoto Wakeshima Yukio Hinatsu 《Journal of solid state chemistry》2004,177(3):739-744
Ternary iridium oxides Ln3IrO7 (Ln=Pr, Nd, Sm, and Eu) were prepared and their crystal structures, magnetic and thermal properties were investigated. Powder X-ray diffractions (XRDs) were measured for all samples and neutron diffraction (ND) measurements were performed for Pr3IrO7. All the profiles were refined with space group Cmcm (No. 63). The lattice parameters for Pr3IrO7 refined by using ND data are a=10.9782(13) Å, b=7.4389(9) Å, and c=7.5361(9) Å. From specific heat and differential thermal analysis (DTA) measurements, Ln3IrO7 (Ln=Pr, Nd, Sm, and Eu) show thermal anomalies at 261, 342, 420, and 485 K, respectively. The results of powder high-temperature XRD and ND measurements indicate that these anomalies are due to the structural phase transition. Magnetic susceptibilities of these compounds were measured in the temperature range between 1.8 and 400 K. Nd3IrO7 shows an antiferromagnetic transition at 2.6 K. A specific heat anomaly has also been observed at the same temperature. For Ln3IrO7 (Ln=Pr, Sm, and Eu), no magnetic anomalies have been found in the experimental temperature range. 相似文献
3.
Samuel J. Mugavero III 《Journal of solid state chemistry》2005,178(1):200-206
Single crystals of a series of lanthanide lithium iridium oxides, Ln2LiIrO6 (Ln=La, Pr, Nd, Sm, Eu) with the double perovskite structure have been grown from molten LiOH/KOH fluxes. The compounds crystallize in a distorted 1:1 rock salt lattice of Li+ and Ir5+ cations in the monoclinic space group P21/n. The magnetic susceptibilities of Ln2LiIrO6 (Ln=Pr, Nd, Sm, Eu) are presented. 相似文献
4.
Hiroaki Nishimine 《Journal of solid state chemistry》2005,178(4):1221-1229
Ternary lanthanide-molybdenum oxides Ln3MoO7 (Ln=La, Pr, Nd, Sm, Eu) have been prepared. Their structures were determined by X-ray diffraction measurements. They crystallize in a superstructure of cubic fluorite and the space group is P212121. The Mo ion is octahedrally coordinated by six oxygens and the slightly distorted octahedra share corners forming a zig-zag chain parallel to the b-axis. These compounds have been characterized by magnetic susceptibility and specific heat measurements. The La3MoO7 shows complex magnetic behavior at 150 and 380 K. Below these temperatures, there is a large difference in the temperature-dependence of the magnetic susceptibility measured under zero-field-cooled condition and under field-cooled condition. The Nd3MoO7 show a clear antiferromagnetic transition at 2.5 K. From the susceptibility measurements, both Pr3MoO7 and Sm3MoO7 show the existence of magnetic anomaly at 8.0 and 2.5 K, respectively. The results of the specific heat measurements also show anomalies at the corresponding magnetic transition temperatures. The differential scanning calorimetry measurements indicate that two phase-transitions occur for any Ln3MoO7 compound in the temperature range between 370 and 710 K. 相似文献
5.
Ternary rare earth antimonates Ln3SbO7 (Ln=rare earths) were prepared and their structures were determined by X-ray diffraction measurements. They crystallize in an orthorhombic superstructure of cubic fluorite (space group Cmcm for Ln=La, Pr, Nd; C2221 for Ln=Nd-Lu), in which Ln3+ ions occupy two different crystallographic sites (the 8-coordinated and 7-coordinated sites). Their magnetic properties were characterized by magnetic susceptibility and specific heat measurements from 1.8 to 400 K. The Ln3SbO7 (Ln=Nd, Gd-Ho) compounds show an antiferromagnetic transition at 2.2-3.2 K. Sm3SbO7 and Eu3SbO7 show van Vleck paramagnetism. Measurements of the specific heat down to 0.4 K for Gd3SbO7 and the analysis of the magnetic specific heat indicate that the antiferromagnetic ordering of the 8-coordinated Gd ions occur at 2.6 K, and the 7-coordinated Gd ions order at a furthermore low temperature. 相似文献
6.
Crystal structures and magnetic properties of the ternary oxides Ln3NbO7 (Ln=La, Pr, Nd, Sm-Lu) are reported. Their powder X-ray diffraction measurements and Rietveld analyzes show that they have the fluorite-related structures with space group Pnma (Ln=La, Pr, Nd), C2221 (Ln=Sm-Tb), or Fm-3m (Ln=Dy-Lu). Magnetic susceptibility measurements were carried out from 1.8 to 400 K. The Ln3NbO7 compounds for Ln=Pr, Gd, Dy-Yb show Curie-Weiss paramagnetic behavior, and Sm3NbO7 and Eu3NbO7 show van Vleck paramagnetism. On the other hand, two magnetic anomalies were observed for both Nd3NbO7 (0.6 and 2.7 K) and Tb3NbO7 (2.0 and 3.2 K). From the results of specific heat measurements, it was found that these anomalies are due to the antiferromagnetic ordering of Ln ions in two different crystallographic sites (the 8-coordinated and 7-coordinated sites). 相似文献
7.
Ismail Ijjaali 《Journal of solid state chemistry》2005,178(5):1503-1507
The quaternary oxychalcogenides Ln4MnOSe6 (Ln=La, Ce, Nd), Ln4FeOSe6 (Ln=La, Ce, Sm), and La4MnOS6 have been synthesized by the reactions of Ln (Ln=La, Ce, Nd, Sm), M (M=Mn, Fe), Se, and SeO2 at 1173 K for the selenides or by the reaction of La2S3 and MnO at 1173 K for the sulfide. Warning: These reactions frequently end in explosions. These isostructural compounds crystallize with two formula units in space group of the hexagonal system. The cell constants (a, c in Å) at 153 K are: La4MnOSe6, 9.7596(3), 7.0722(4); La4FeOSe6, 9.7388(4), 7.0512(5); Ce4MnOSe6, 9.6795(4), 7.0235(5); Ce4FeOSe6, 9.6405(6), 6.9888(4); Nd4MnOSe6, 9.5553(5), 6.9516(5); Sm4FeOSe6, 9.4489(5), 6.8784(5); and La4MnOS6, 9.4766(6), 6.8246(6). The structure of these Ln4MOQ6 compounds comprises a three-dimensional framework of interconnected LnOQ7 bicapped trigonal prisms, MQ6 octahedra, and the unusual LnOQ6 tricapped tetrahedra. 相似文献
8.
K. YoshiiH. Abe 《Journal of solid state chemistry》2002,165(1):131-135
Magnetic data are presented for LnMnO3 (Ln=Ho, Er, Tm, Yb, and Lu) having the hexagonal crystal structure of P63cm. DC magnetization measurements show that magnetic order is not clearly observed for Ln=Ho-Yb, while an antiferromagnetic transition of the Mn3+ moments is found at ∼90 K for LuMnO3, where the Lu3+ ion has no 4f localized moment. This is ascribed to both the paramagnetism of Ln3+ and the suppression of magnetization in the Mn3+ sublattices arising from strong antiferromagnetic interactions between Mn3+. Deviation from the Curie-Weiss law at low temperatures indicates the onset of antiferromagnetism. Some magnetization data of Ca-substituted compounds, Ln0.5Ca0.5MnO3, which have the different crystal structure of orthorhombic Pnma, are also discussed briefly. 相似文献
9.
Crystalline cobalticyanides LnCoIII(CN)6·nH2O with Ln = La,…, Lu, Y have been synthesized by a double-infusion technique. In analogy to the Cr and Fe compounds, the large rare-earth ions form a hexagonal modification while the smaller ions lead to the orthorhombic structure with 4H2O. Experiments show that no magnetic ordering occurs down to 1°K. The Stark splitting of the J ground state due to the crystalline field is analyzed for the Ce and Sm compounds. 相似文献
10.
Makoto Wakeshima 《Journal of solid state chemistry》2006,179(11):3575-3581
Ternary lanthanide rhenium oxides Ln3ReO7 (Ln=Sm, Eu, Ho) were prepared and their structures were determined by X-ray diffraction measurements. They crystallize in an orthorhombic superstructure of cubic fluorite (space group Cmcm for Ln=Sm, Eu; C2221 for Ln=Ho). The magnetic properties were characterized by magnetic susceptibility and specific heat measurements from 1.8 to 400 K. The Sm3ReO7 shows an antiferromagnetic transition at 1.9 K. The Eu3ReO7 indicates a magnetic anomaly at 12 K. On the other hand, the results of the specific heat measurements indicate that both Sm3ReO7 and Eu3ReO7 undergo a structure transition at 270 and 350 K, respectively. The Ho3ReO7 is paramagnetic down to 1.8 K. 相似文献
11.
A series of rare-earth iron borates having general formula LnFe3(BO3)4 (Ln=Y, La-Nd, Sm-Ho) were prepared and their magnetic properties have been investigated by the magnetic susceptibility, specific heat, and 57Fe Mössbauer spectrum measurements. These borates show antiferromagnetic transitions at low temperatures and their magnetic transition temperatures increase with decreasing Ln3+ ionic radius from 22 K for LaFe3(BO3)4 to 40 K for TbFe3(BO3)4. In addition, X-ray diffraction, specific heat, and differential thermal analysis (DTA) measurements indicate that the phase transition occurs for the LnFe3(BO3)4 compounds with Ln=Eu-Ho, Y, and its transition temperature increases remarkably with decreasing Ln3+ ionic radius from 88 K for Ln=Eu to 445 K for Ln=Y. 相似文献
12.
A series of new compounds Ln(GaM2+)O4 and Ln(AlMn2+)O4 having a layer structure were successfully prepared [Ln = Lu, Yb, Tm, Er, Ho, and Y, and M = Mg, Mn, Co, Cu, and Zn]. The synthesis conditions and the unit cell parameters for 23 compounds have been determined. These compounds are isostructural with YbFe2O4 (space group Å, and c = 25.109(2) Å). 相似文献
13.
C. Boyer-CandalenJ. Derouet P. Porcher Y. MoëloA. Meerschaut 《Journal of solid state chemistry》2002,165(2):228-237
The optical properties of Ln2Ti2S2O5 compounds (Ln=Nd, Sm, Gd, Tb, Dy, Ho, Er, and Y) have been measured. Diffuse reflectance spectra revealed a strong absorption band above 2 eV, which explains the color of the compounds. Moreover, other bands, with a lower intensity, have been attributed to 4f-4f rare earth transitions. In the case of neodymium the derived energy level scheme is rich enough to determinate a set of phenomenological crystal field parameters that correctly reproduce the spectrum. These parameters were also calculated from the crystallographic structure, in a good agreement with the experiment. Finally, the paramagnetic susceptibility, well reproduced by the calculation, confirms that the rare earth is in a trivalent state. 相似文献
14.
Yuki Shimoda 《Journal of solid state chemistry》2010,183(1):33-40
Quadruple perovskites Ba4LnRu3O12 (Ln=La, Nd, Sm-Gd, Dy-Lu) were prepared and their magnetic properties were investigated. They adopt the 12L-perovskite-type structure consisting of Ru3O12 trimers and LnO6 octahedra. All of these compounds show an antiferromagnetic transition at 2.5-30 K. For Ba4NdRu3O12, ferrimagnetic ordering has been observed at 11.5 K. The observed magnetic transition is due to the magnetic behavior of the Ru4.33+3O12 trimer with S=. Magnetic properties of Ba4LnRu3O12 were compared with those of triple perovskites Ba3LnRu2O9 and double perovskites Ba2LnRuO6. 相似文献
15.
One-dimensional GdVO4:Ln3+ (Ln=Eu, Dy, Sm) nanofibers have been prepared by a combination method of sol-gel process and electrospinning technology. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL), quantum efficiency (QE), and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. The XRD, FT-IR, and TG-DTA results show that GdVO4:Ln3+ nanofibers samples crystallize at 700 °C. SEM images indicate that the as prepared precursor fibers are smooth. After being calcined at 700 °C for 4 h, the fibers still maintain their fiberlike morphology with rough surface. TEM image further manifests that the GdVO4:Ln3+ nanofibers consist of nanoparticles. Under ultraviolet excitation and low-voltage electron beam excitation, GdVO4:Ln3+ phosphors showed their strong characteristic emission due to an efficient energy transfer from vanadate groups to dopants. The optimum doping concentration of Ln3+ in the GdVO4 nanofibers also has been investigated. 相似文献
16.
Ichimin Shirotani Yousuke Shimaya Chihiro Sekine 《Journal of solid state chemistry》2003,174(1):32-34
New filled skutterudites with heavy lanthanide, LnFe4P12 (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) have systematically been prepared for the first time by the high-pressure technique. The relationship between lattice constants and atomic numbers of lanthanide (including Y) is established for LnFe4P12. Electrical and magnetic properties of several new filled skutterudites with heavy lanthanide have been studied at low temperatures; YFe4P12 shows a superconducting transition at around 7 K, and DyFe4P12 behaves as a ferromagnet below 10 K. Electrical and magnetic anomalies in DyFe4P12 and YFe4P12 are mainly discussed. 相似文献
17.
Yuki Shimoda 《Journal of solid state chemistry》2009,182(10):2873-2879
New quadruple perovskite oxides Ba4LnIr3O12 (Ln=lanthanides) were prepared and their magnetic properties were investigated. They crystallize in the monoclinic 12L-perovskite-type structure with space group C2/m. The Ir3O12 trimers and LnO6 octahedra are alternately linked by corner-sharing and form the perovskite-type structure with 12 layers. The Ln and Ir ions are both in the tetravalent state for Ln=Ce, Pr, and Tb compounds , and for other compounds (Ln=La, Nd, Sm-Gd, Dy-Lu), Ln ions are in the trivalent state and the mean oxidation state of Ir ions is . An antiferromagnetic transition has been observed for Ln=Ce, Pr, and Tb compounds at 10.5, 35, and 16 K, respectively, while the other compounds are paramagnetic down to 1.8 K. 相似文献
18.
Makoto Wakeshima 《Journal of solid state chemistry》2010,183(11):2681-2688
Magnetic properties and structural transitions of ternary rare-earth transition-metal oxides Ln3MO7 (Ln=rare earths, M=transition metals) were investigated. In this study, we prepared a series of molybdates Ln3MoO7 (Ln=La-Gd). They crystallize in an orthorhombic superstructure of cubic fluorite with space group P212121, in which Ln3+ ions occupy two different crystallographic sites (the 8-coordinated and 7-coordinated sites). All of these compounds show a phase transition from the space group P212121 to Pnma in the temperature range between 370 and 710 K. Their magnetic properties were characterized by magnetic susceptibility measurements from 1.8 to 400 K and specific heat measurements from 0.4 to 400 K. Gd3MoO7 shows an antiferromagnetic transition at 1.9 K. Measurements of the specific heat for Sm3MoO7 and the analysis of the magnetic specific heat indicate a “two-step” antiferromagnetic transition due to the ordering of Sm magnetic moments in different crystallographic sites, i.e., with decreasing temperature, the antiferromagnetic ordering of the 7-coordinated Sm ions occur at 2.5 K, and then the 8-coordinated Sm ions order at 0.8 K. The results of Ln3MoO7 were compared with the magnetic properties and structural transitions of Ln3MO7 (M=Nb, Ru, Sb, Ta, Re, Os, or Ir). 相似文献
19.
A new series of gallozincates LnBaZn3GaO7 (Ln=La, Nd, Sm, Eu, Gd, Dy, Y) and new aluminozincates LnBaZn3AlO7 (Ln=Y, Eu, Dy) have been synthesized. Their structure refinements show that these phases belong to the “114” series, with hexagonal P63mc space group previously described for SmBaZn3AlO7. The photoluminescence study of these oxides shows that the Eu3+ activated LnBaZn3MO7 oxides with Ln=Y, La, Gd; and M=Al, Ga exhibit strong magnetic and electric dipole transitions (multiband emission) which is of interest for white light production. These results also confirm that the site occupied by Eu3+ is not strictly centrosymmetric. The electric dipole transition intensity is the highest in GdBaZn3MO7 [M=Al, Ga]: 0.05Eu3+ as compared with other Eu3+ activated compositions. This is due to the layer distortion around GdO6 octahedra when compared with YO6 and LaO6 octahedra. 相似文献
20.
Two series of elpasolite perovskites Ln2CoMnO6 and Ln2NiMnO6 (Ln=La, Pr, Nd, Sm, Gd) have been prepared. The electronic band gap and magnetic Curie temperature vary systematically as a function of the rare earth cation size within both series. Here we used Raman scattering spectroscopy along with the results of previous structural studies to show that there is little change in octahedral distortion but significant changes in the octahedral tilting angle upon decreasing lanthanide ionic radius. The data indicate differences in the orbital overlap and bond strengths between the two series of materials that allow us to understand variations in the magnetic and electrical properties within and between the two perovskite series. 相似文献