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Osmotic swelling behaviors in layered perovskite niobate were examined in aqueous solutions containing three types of amine-related agents including quaternary ammonium hydroxides and tertiary aminoethanol. Platelet microcrystals of a protonated layered perovskite niobate, HCa2Nb3O10·1.5H2O, were found to show enormous swelling in the aqueous solutions, which was clearly recognized by the noticeable expansion of the sample volume over 100-fold. Optical microscopy observations revealed that the crystals underwent accordion-like elongation in the layer-stacking direction up to several ten-fold the initial thickness. Small-angle X-ray scattering measurements of swollen samples indicate the expansion of interlayer separation ranging from ∼20 nm to over 100 nm, which is primarily governed by the concentrations of the amine-related agents. The magnitudes of the interlayer separation were comparable to those of the macroscopic swelling. The degree of swelling was progressively suppressed with further increasing concentration, and this suppression trend was related to the amines.

Crystals of co-doped gadolinium oxyhydroxide (GdOOH), Gd 0.98 Eu 0.02– x Tb x OOH and Gd 1– y – z Dy y Bi z OOH, were synthesized by a flux method. The color coordinates in the Commission Internationale de I'Eclairage (CIE) chromaticity diagram of Gd 0.98 Eu 0.02– x Tb x OOH, obtained under 254 nm irradiation, shifted along a straight line with the changing values of x to include the yellow region. The CIE coordinates of Dy 3+ doped in GdOOH were located in the yellow region, while the emission intensity of Dy 3+ under 286 nm irradiation increased by more than 40 times when co-doped with Bi 3+ .

The surface charge of various anionic unilamellar nanosheets, such as graphene oxide (GO), Ti0.87O2(0.52-), and Ca2Nb3O10(-) nanosheets, has been successfully modified to be positive by interaction with polycations while maintaining a monodispersed state. A dilute anionic nanosheet suspension was slowly added dropwise into an aqueous solution of high molecular weight polycations, which attach on the surface of the anionic nanosheets via electrostatic interaction. Surface modification and transformation to positively charged nanosheets were confirmed by various characterizations including atomic force microscopy and zeta potential measurements. Because the sizes of the polycations used are much larger than the nanosheets, the polymer chains may run off the nanosheet edges and fold to the fronts of the nanosheets, which could be a reason for the continued dispersion of the modified nanosheets in the suspension. By slowly adding a suspension of polycation-modified nanosheets and pristine anionic nanosheet dropwise into water under suitable conditions, a superlatticelike heteroassembly can be readily produced. Characterizations including transmission electron microscopy and X-ray diffraction measurements provide evidence for the formation of the alternately stacked structures. This approach enables the combination of various pairs of anionic nanosheets with different functionalities, providing a new opportunity for the creation of unique bulk-scale functional materials and their applications.

Europium oxyhydroxide crystals were synthesized by the flux method. The as-grown crystals were transparent and had a plate-like shape with natural flat surfaces. The powder XRD data were refined by assuming a monoclinic structure of the space group P 2 1 /m and lattice parameters of a =0.4346 nm, b =0.3744 nm, c =0.6107 nm, and β=108.62°. The magnetic susceptibility of the EuOOH crystals exhibited typical Van Vleck temperature-independent paramagnetism below 120 K. The calculated susceptibility, based on Van Vleck's theory, agreed with the experimental data to some extent, with the coupling constant λ=458±10 K. The experimental results were in close agreement with the results calculated using a modified formula with λ=505±2 K and a constant term C =4.6×10 −4 emu/(mol·Oe).

Platelet crystals of a layered perovskite showed massive accordion-like swelling in a tetrabutylammonium hydroxide solution. The permeation of the solution induced the huge expansion of the interlayer spacing as well as the crystal thickness up to 50-fold, leading to a very high water content of >90 wt%.

Epitaxial LiCoO2 films are synthesized using a sol–gel method. The precursors are aqueous solutions of acetates or nitrates of Li and Co with polyvinylpyrrolidone as a thickener. The LiCoO2 films prepared from the solutions by spin coating are epitaxially grown on sapphire (0001) substrates with c-axis orientation and in-plane alignment of LiCoO2 [ 1 1 ¯ 0 ] ‖sapphire [100]. A two-step heat treatment of the spin-coated films consisting of preheating on a hotplate at the crystallization temperature followed by a high-temperature treatment notably promotes the c-axis orientation. In addition, the crystal orientation is controllable on different planes of the SrTiO3 substrates; the LiCoO2 films are grown with epitaxial relationships of LiCoO2 (001)‖SrTiO3 (111), LiCoO2 (018)‖SrTiO3 (110), and LiCoO2 (104)‖SrTiO3 (100).

Na + extraction from Na 2 Ti 2 Sb 2 O has been attempted using polytetrafluoroethylene (PTFE; empirical formula CF 2 ) as the extraction reagent. Systematic increase in both lattice parameters a along the intralayer direction and c along the interlayer direction was observed with respect to the reacted PTFE amounts, suggesting the successful deintercalation of the interlayer Na + . In addition, ferromagnet-like behavior, which is rare for systems consisting of ions with low magnetic moments, such as Ti 3+ (d 1 ), was observed in the Na + -deintercalated Na 2 Ti 2 Sb 2 O. This result suggests that the method of alkali–metal ion extraction using polytetrafluoroethylene as an extraction reagent (AEP) can be utilized in order to induce interesting and important properties in compounds including highly air- and solvent-sensitive mixed-anion compounds such as Na 2 Ti 2 Sb 2 O.

A new upconversion (UC) material was designed by flocculating a Ca2Nb3O10– nanosheet, which acts as thermal and structural stabilizer, with Ho3+ photoactivator, Yb3+ sensitizer, and Y3+ space filler. The flocculated product consists of the restacked nanosheets and the rare-earth ions in the internanosheet gallery. The restacked sheet faces of the Ca2Nb3O10– nanosheet building blocks are self-organized in a parallel manner, and their crystallographic coherency extends to three layers on average. On the other hand, the nanosheet building blocks are randomly staggered along the in-layer direction. Chemical composition of the flocculated product was estimated as (Ho0.096Yb0.23Y0.164)Ca1.76□0.24Nb3O10·1.4H2O. Heat treatment of the flocculated product at 500 °C was necessary in order to suppress nonradiative energy loss via OH vibration and to induce UC emission. Even after the heat treatment, perovskite-type atomic arrangement of the Ca2Nb3O10– nanosheet building block was retained. Upon laser irradiation at 9...

The alkali-metal ion extraction ability of an inert material, polytetrafluoroethylene (PTFE; empirical formula CF2), was clarified by characterizing a partially alkali-metal ion-extracted layered compound, K0.8(Li0.27Ti1.73)O4. Washing K0.8(Li0.27Ti1.73)O4 in water extracts only 44% of the interlayer K(+) and no intralayer Li(+); on the other hand, 53% of the interlayer K(+) and approximately 10% of the intralayer Li(+) ions were extracted from K0.8(Li0.27Ti1.73)O4 by the reaction with PTFE at 350 °C under flowing Ar. A systematic decrease in the lattice parameters a and c along the intralayer directions and an increase in b along the interlayer direction were observed, consistent with the alkali-metal ion deintercalation amount as a function of the reaction temperatures and the reacted PTFE amounts. After the reaction with K0.8(Li0.27Ti1.73)O4 : CF2 = 1 : 0.6 in mol, the lattice parameter b increased to 1.5607(3) nm from 1.5522(2) of the pristine K0.8(Li0.27Ti1.73)O4, and this change in the lattice parameter was approximately one order of magnitude larger than those in a and c.

One of the basic requirements for attaining a good epitaxy is a close structural matching between a substrate and a growing crystal epilayer. This restrictive requirement causes a major obstacle for its wide application to a range of functional crystal films in electronic, magnetic or optical devices. One approach for overcoming this problem is the so-called van der Waals epitaxy (VDWE) method, which can effectively implement the epitaxy of various crystals on cleaved faces of layered materials having no dangling bonds. The weak adatom–substrate interaction without directional covalent bonding plays a crucial role in the initial stage of VDWE, which drastically relaxes the lattice matching limitation. However, the method requires special materials for use as a substrate, thereby meaning that its applicability is limited. In this study, the concept is extended to the two-dimensional (2D) lattice of inorganic nanosheets, which are molecularly thin 2D crystals produced via artificial exfoliation of layered metal oxides. The nanosheets can neatly cover the surface of conventional substrates such as glass via a facile solution-based process. Similar to the above-mentioned cleaved faces of layered materials, such substrates can promote VDWE-like crystal growth because of their dangling bond-free nature. Based on this principle, we have demonstrated a selective deposition of highly textured (100), (110) and (111) SrTiO3 films, a fundamentally important archetype of functional crystals, on glass substrates covered with single-layer nanosheets with suitable 2D periodicities as a trigger for VDWE-like film growth. The rich varieties of nanosheet structures and their facile deposition onto almost any kinds of substrates provide a significant advantage, expanding potential applications for a range of devices based on functional crystal films.

Eu3+-doped gadolinium oxyhydroxide Gd1-xEuxOOH crystals were synthesized by the flux method. The X-ray diffraction data for the crystals were well refined assuming a monoclinic structure with the P21/m space group. Gd1-xEuxOOH (x ≤ 0.2) crystals showed strong red emission, and the highest fluorescence quantum yield (Φf) was 0.27, obtained for x = 0.10. Φf decreased rapidly as the Eu3+ content x increased above 0.2, owing to concentration quenching. Analysis with a percolation model indicated three-dimensional energy transfer between the Eu3+ ions.

The crystallographic, magnetic and transport properties of Sr1−x Ca x Ru0.5Mn0.5O3 were studied to reveal the effects of crystal symmetry on the magnetism and the transport properties of antiferromagnetic SrRu1−y Mn y O3 (y > 0.2). The Ca-content dependences of the lattice constants and volume suggest that the mixed valence state of Mn3+, Mn4+, Ru4+, and Ru5+ ions in SrRu0.5Mn0.5O3 is held for Ca substitution. However, a structural transformation from tetragonal to orthorhombic symmetry occurs at a Ca content of x ∼ 0.2, and a ferromagnetic state appears simultaneously. The Weiss temperature of all samples has a positive value regardless of the magnetic state. The resistivity decreases as the Ca content increases, and the high temperature part of the resistivity could be fitted by using the variable range hopping (VRH) model. The localization length increases as soon as ferromagnetism appears. The Curie temperature seems to depend on the distance between transition metal ions. The antiferromagnetic state was explained by using the competition between a ferromagnetic interaction along the c-axis and an antiferromagnetic interaction in the ab-plane, and the orthorhombic ferromagnetic state was explained by using a three-dimensional ferromagnetic interaction between Mn ions.

We report the composition-induced metal–insulator crossover transition in Ti substituted Ru-based metallic full Heusler alloy Ru2MnGe where the both end of materials shows a metallic properties. The samples at the middle composition show the large negative magnetoresistance effect. The experimental results of the resistivity and the magnetization indicate that this metal–insulator transition is induced by the Kondo effect because Ti atoms on antiferromagnetic Ru2MnGe have an important role in appearance of insulator states.

A new method for the crystal growth of alkaline-earth palladate CaPd3O4 was developed. The crystals were synthesized on a voltage-applied electrode in a molten chloride solvent. The maximum length of the crystal was about 1.5 mm. The X-ray diffraction data were refined well by assuming a cubic structure of the space group Pm n, and the lattice constant a was 5.7471 (10) ?. The temperature dependence of the resistivity showed semiconductor-like characteristics with a very small activation energy Ea of 0.45 meV at low temperatures, and the resistivity at 300 K was 0.1 cm. The temperature dependence of the molar magnetic susceptibility showed the Curie-Weiss paramagnetic behavior with a small molar Curie constant Cmol of 5.0(1) × 10-3 emu K/(mol Oe), indicating the existence of localized spin moments.

The present study reveals that the correlation between the magnetic properties with composition x in the polycrystalline Ru2Mn1−xFexGe system. Hard ferromagnetic properties appeared at the intermediate composition between antiferromagnetic Ru2MnGe with soft ferromagnetic Ru2FeGe. Ru2Mn0.6Fe0.4Ge shows an anisotropic and negative magnetoresistance (MR) effect more than 8% although the both end materials are small MR effect less than 1%. These experimental results correlate the variation in MR ratio with that of coercive field as a function of x. Moreover, the correlation is shown at the boundary of magnetism between antiferromagnetic and ferromagnetic. Therefore, the present experimental results imply that the coexistence of antiferromagnetic and soft ferromagnetic leads to induce the MR effect in this system.

Combining different materials into desired superlattice structures can produce new electronic states at the interface and the opportunity to create artificial materials with novel properties. Here we introduce a new, rather unexpected, and yet simple way to such a superlattice assembly of perovskite oxides: in the Dion-Jacobson phase, a model system of layered perovskites, high-quality bicolor perovskite superlattices (LaNb(2)O(7))(nL)(Ca(2)Nb(3)O(10))(nC) are successfully fabricated by a layer-by-layer assembly using two different perovskite nanosheets (LaNb(2)O(7) and Ca(2)Nb(3)O(10)) as a building block. The artificially fabricated (LaNb(2)O(7)/Ca(2)Nb(3)O(10)) superlattices are structurally unique, which is not feasible to create in the bulk form. By such an artificial structuring, we found that (LaNb(2)O(7)/Ca(2)Nb(3)O(10)) superlattices possess a new form of interface coupling, which gives rise to ferroelectricity.

The crystallographic and magnetic properties of perovskite-type rhodite Ln RhO 3 ( Ln = rare-earth ions except Ce and Pm) were studied. Ln RhO 3 ( Ln = La, Eu, Lu) shows paramagnetism with very small susceptibility, suggesting that the Rh 3+ ion has no magnetic moment. Ln RhO 3 ( Ln = Nd, Sm, Gd, Tb, Dy, Ho, Er, Yb) shows antiferromagnetic transition at temperatures between 0.5 and 3.5 K; however, no transition was observed for Ln RhO 3 ( Ln = Pr, Tm) down to 0.5 K. The effective moment μ eff agrees with the theoretical moment of free rare-earth ions, indicating the dominant magnetic contribution of rare-earth ions. The Weiss temperature Θ has a strong correlation with the spin value of rare-earth ions, suggesting that the superexchange interaction is a dominant interaction in Ln RhO 3 . The magnetization of antiferromagnetic samples tends to be saturated above 20–30 kOe, but the moments at 70 kOe are far from the theoretical moments. Antiferromagnetic samples seem to have an intermediate state and require a more intense magnetic field to attain saturation.

The single crystal of the new ternary compound Sm 12 Fe 14 Al 5 was grown and its crystallographic and magnetic properties were investigated. Sm 12 Fe 14 Al 5 has a hexagonal structure of the space group p-3m1 and shows ferromagnetism with a Curie temperature of 245 K. The easy direction of magnetization is parallel to the c -axis at temperatures between 245 and 85 K; however, it changes to the c -plane below 85 K through a first-order-like phase transition. No saturation is observed in the magnetization curve even under the applied field of 55 kOe at 5 K. Sm 12 Fe 14 Al 5 seems to have a large coercive field at very low temperatures. The anisotropy field was estimated at 5 and 120 K and the saturation magnetization of low temperature phase is explained assuming a ferromagnetic coupling between Fe and Sm sublattices.

The synthesis of a series of new layered rare-earth hydroxide solid solutions and their transformation into (EuxGd1−x)2O3 crystallites are described. Highly crystalline platelets of EuxGd1−x(OH)2.5Cl0.5·0.9H2O solid solutions with various Eu3+/Gd3+ ratios were prepared through a homogeneous precipitation method. The hydroxide solid-solution samples exhibited characteristic Eu3+ photoluminescence properties through the energy transfer from Gd3+ to Eu3+ and the self-excitation of Eu3+. Cubic (EuxGd1−x)2O3 crystallites were obtained via quasi-topotactic transformation of EuxGd1−x(OH)2.5Cl0.5·0.9H2O solid solutions above 800 °C. The as-transformed cubic (EuxGd1−x)2O3 crystallites well retained the original platelet morphology and single crystalline nature, and exhibited greatly enhanced photoluminescence properties with respect to the precursor hydroxides. The Eu3+ content of 0.05 in the cubic (EuxGd1−x)2O3 gave a maximum luminescence intensity, which is comparable with that of a commercial Y2O3:Eu phosphor.

The performance of phosphate glasses as a catalyst for water decomposition and a proton conductor was investigated. Glasses with a composition of 30Na2O–10BaO–30P2O5–(30−x)WO3–xNb2O5 (5

The bulk layered compound KLa0.90Sm0.05Nb2O7 and its exfoliated form of La0.90Sm0.05Nb2O7 nanosheet have been prepared, and their photoluminescence properties have been characterized. The photoluminescence emission of KLa0.90Sm0.05Nb2O7 via host excitation is negligibly low in intensity, whereas the emission via direct Sm3+ excitation has apparently been observed. On the contrary, the emission via direct Sm3+ excitation is preferentially quenched, and the emission via host excitation becomes far more predominant than that via direct Sm3+ excitation for the exfoliated La0.90Sm0.05Nb2O7 nanosheet. From the comparison of photoluminescence properties between the bulk layered compound KLa0.90Sm0.05Nb2O7 and its exfoliated form of La0.90Sm0.05Nb2O7 nanosheet, the relative enhancement of the host excitation-mediated photoluminescence by exfoliation of bulk Ln-photoactivated layered phosphors into nanosheets as a general trend has become more apparent.

Crystals of ternary LnRu2P2 (Ln = Pr, Nd, Sm, Tb, Dy, Er) systems were synthesized, and their crystallographic, magnetic, and electric properties were investigated. All the crystals have a tetragonal ThCr2Si2-type structure of space group I4/mmm. The lattice constants decrease as the number of 4f electrons increases, reflecting the lanthanide contraction. An antiferromagnetic transition was observed for LnRu2P2 (Ln = Pr, Nd, Sm, Tb, Dy) at 25 K (Pr), 19 K (Nd), 15 K (Sm), 22.5 K (Tb), and 13 K (Dy). However, no transition was observed for ErRu2P2 down to 5 K. The Peff agrees well with the theoretical moment g J ( J + 1 ) of lanthanides, suggesting that lanthanides make a major contribution to the magnetic moment of LnRu2P2. A spin-flop-like transition was observed in the M(H) curves of PrRu2P2 and TbRu2P2 at 4 and 8 kOe, respectively; however, no saturation was observed up to 55 kOe.

Single crystals of CaRu 1− x Mn x O 3 and SrRuO 3 were grown using an electrochemical technique with calcium or strontium chloride as a solvent, and the crystallographic properties of grown crystals were characterized by single-crystal X-ray diffraction and powder X-ray diffraction. CaRu 1− x Mn x O 3 and SrRuO 3 crystals with natural surfaces were obtained on the cathode, reflecting the characteristic of the growth in a liquid phase. In spite of the low synthesis temperature of 780 °C, the size of CaRuO 3 crystals was relatively large (∼2.5 mm in length). The Mn content of grown crystals was in proportion to the molar ratio of Mn 2 O 3 /RuO 2 at the synthesis, and CaRu 1− x Mn x O 3 crystals with different compositions could be obtained by only changing the ratio of the raw materials.

Single crystals of neodymium oxyhydroxide NdOOH were grown using an electrochemical method. Crystals having a maximum size of about 2 mm in length were grown. The structure was identified by single crystal X-ray diffraction and the refinement converged to R1 = 0.0170 and wR1 = 0.0426. NdOOH crystallizes in a monoclinic structure of the space group P2 1 / m with lattice parameters of a = 4.3896(2) A, b = 3.8319(2) A, c = 6.2424(3) A, and β = 108.131(2)°, and Z = 2. The resistivity shows semiconductor-like characteristics with the activation energy E a = 0.93 eV. No magnetic order was found down to 5 K.

Eu3+-activated double perovskite-type nanosheet phosphor (K1.5Eu0.5)Ta3O10 has been prepared by the soft chemical exfoliation reaction of K(K1.5Eu0.5)Ta3O10 bulk precursor. The lateral size of the nanosheet product ranges from 0.1 to a few micrometers, and the thickness is uniformly 2.4(2) nm. The lattice parameter along the sheet direction obtained by the in-plane X-ray diffraction is 0.3933(3) nm, corresponding to the typical O−Ta−O distances. The photoluminescence emission can be obtained either by host or by direct photoactivator excitation, but the host excitation yields much higher emission intensity than does the direct photoactivator excitation. The emission spectra show relatively sharp peaks from the 5D0 → 7FJ manifold transitions of Eu3+. The highest emission intensity is observed around 704 nm (far-red) from the 5D0 → 7F4 transition of Eu3+.

High photoactivator concentration nanosheets Eu0.56Ta2O7 have been prepared by the soft chemical exfoliation reaction of the layered perovskite Li2-xHxEu0.56Ta2O7 with a tetrabutylammonium hydroxide aqueous solution. In-plane X-ray diffraction and TEM and AFM observation results indicate that the Eu0.56Ta2O7 nanosheet is crystalline and retains the layered perovskite structural feature of the bulk precursors. The most intense emission is observed from the 5D0 → 7F2 transition of Eu3+. The intensity of this emission by the host excitation exceeds 18 times that by the direct Eu3+ excitation.

Synthesis and characterization of Sr1−xAxPd3O4 (A = Na, Bi) are reported. All the doped phases crystallize in the cubic symmetry with the space group Pm3m. Both Hall and thermopower measurement results indicate that substitutions of Na+ and Bi3+ into the Sr2+ site introduce hole and electron carriers, respectively. As the dopant concentration increases, effective magnetic moment, electrical conductivity and carrier concentration of these phases increase and thermopower decreases. The highest power factor obtained among these doped samples is 0.5 μW/K2 cm at room temperature for Sr0.8Na0.2Pd3O4.

A series of orthorhombic NaLnTiO 4 (Ln = lanthanides) has been synthesized and characterized. These compounds all crystallize in A-site ordered n = 1 Ruddlesden–Popper phase (A n +1 B n O 3 n +1 ) structure. The weak ferromagnetism with large magnetization has been observed for Ln = Tb and Dy, and non-linear field dependence of magnetization without hysteresis has been observed for Ln = Er and Ho. By performing the symmetry operations, two possible canted spin arrangements have been proposed.

Magnetic properties of a series of orthorhombic Na Ln TiO 4 ( Ln = Sm, Eu, Gd, Tb, Dy, Ho and Er) characterized by heat capacity measurements are reported. Magnetic transitions are observed for all Na Ln TiO 4 investigated except for Ln = Eu. The change in magnetic entropy closely agrees with the expected theoretical values except for Ln = Sm and Gd. Peak profiles in temperature dependence of heat capacity indicate that Ln = Sm, Tb, Dy, Ho and Er phases possess Ising square lattices. Furthermore, Ln = Gd also exhibits the similar property regardless of its S state; there seems some degree of anisotropy in its magnetic lattice. Magnetization and heat capacity data indicate that superexchange through oxygen is the dominant spin interaction in this system.

Ln 2 BaPdO 5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Dy, Ho) all crystallizes in Nd 2 BaZnO 5 structure which is proposed to have a Shastry–Sutherland (S–S) lattice of Ln 3+ ions. Ln 2 BaPdO 5 (Ln = Nd, Sm, Gd, Dy, Ho) exhibits antiferromagnetic transitions at temperatures between 2 and 5 K. In addition, metamagnetic transitions have been observed for Ln 2 BaPdO 5 (Ln = Nd, Dy, Ho) below 2 K. Specific heat of Ln 2 BaPdO 5 (Ln = Ho, Dy) exhibits symmetric peaks at T N , and residual entropy below T N is negligibly small. On the contrary, specific heat of Ln 2 BaPdO 5 (Ln = Nd, Sm, Gd) exhibits Schottky type anomalies followed by sharp peaks at T N , and residual entropy below T N is large. From these results, the applicability of the S–S model to Ln 2 BaPdO 5 with various Ln 3+ ions is proposed.

Eu3+-doped perovskite nanosheets, La0.90Eu0.05Nb2O7, have been prepared by the soft chemical exfoliation reaction of K1−xHxLa0.90Eu0.05Nb2O7 with a tetrabuthylammonium hydroxide aqueous solution. The resulting colloidal La0.90Eu0.05Nb2O7 nanosheet suspension exhibits photoluminescence emission from the 5D0 to 7FJ manifold transitions of Eu3+ by either direct excitation of Eu3+ or host excitation, whereas no host emission was observed at room temperature. In the case of the bulk precursors K1−xHxLa0.90Eu0.05Nb2O7, the direct excitation yields more intense emission than the host excitation. On the contrary, the most intense emission from the La0.90Eu0.05Nb2O7 nanosheets was observed by exciting at the broad excitation band maximum (353 nm). The difference in the photoluminescence properties between the La0.90Eu0.05Nb2O7 nanosheets and their bulk precursors seems to be related to the dimensionality of these host structures and the confinement of the energy-transfer process between the host layer units and Eu...

Single crystals of lanthanum oxyhydroxide (LaOOH) were grown using an electrochemical method. Crystals having a maximum size of 7.0 mm in length, 1.5 mm in width, and 0.7 mm in thickness were grown. LaOOH crystallizes in a monoclinic structure of the space group P 2 1 / m with a lattice parameter of a =0.4417 nm, b =0.3926 nm, c =0.6573 nm, and β =112.32°. LaOOH crystals completely changed to lanthanum trihydroxide La(OH) 3 within 48 h in ambient atmosphere by water absorption. Maintenance at 390 °C by heat treatment was effective to maintain the structure of LaOOH for at least a week.

Magnetism of intermetallic compounds SmFe2, SmFe3, Sm6Fe23, and SmFe7 were studied in detail using single crystals and the use of these materials has been discussed. SmFe2 and Sm6Fe23 have cubic magnetocrystalline anisotropy and the easy axis of magnetization in the [111] direction. SmFe2 has giant negative magnetostriction that can be used for microactuator or ultrasonic generator. SmFe3 has a relatively large saturation moment and uniaxial anisotropy, which are promising for application as a perpendicular magnetic recording medium. Large saturation magnetization and extremely large magnetocrystalline anisotropy of SmFe7 seem promising as an absorber in the frequency range of milliwave as well as a high performance permanent magnet.

Phosphate glasses dissociating hydrogen from water vapor were prepared and their performance was evaluated. Glasses with compositions of 30Na2O–10BaO–30P2O5–(30–x)Nb2O5–xWO3 (5

Measurements of core and valence electronic states of single crystals of the rare earth transition metal Zintl phases Yb14MnSb11 and Yb14ZnSb11 were performed using the X-ray photoelectron spectroscopy station of Beamline 7 at the Advanced Light Source. Sample surfaces of Yb14MnSb11 and Yb14ZnSb11 were measured as received, after Ar+ ion bombardment, and after cleaving in situ. The single crystal structure of Yb14ZnSb11 is also reported. Both compounds are air-sensitive and show Yb3+ due to surface oxidation. In the case of Yb14MnSb11, there is no evidence for Yb3+ that would be intrinsic to the sample, consistent with previously reported X-ray magnetic circular dichroism studies. Detailed analyses of the Yb14ZnSb11 surfaces reveal a significant contribution of both Yb3+ and Yb2+ 4f states in the valence band region. This result is predicted for the Zn analog by Zintl counting rules and support the mixed valency of Yb for Yb14ZnSb11. Further detailed analysis of the core and valence band structure of both Yb14MnSb11 and Yb14ZnSb11 is presented.

Single crystals of Na2Ti2Sb2O have been grown by NaSb flux method. It crystallizes in platelet morphology with dark silver color. The growth conditions are optimized and crystal structure has been analyzed by single crystal X-ray diffraction at 88.7, 120.0 and 150.0 K. The structure analysis result shows that there is a non-linear change in temperature-dependent lattice parameters suggesting that previously reported anomaly in temperature-dependent magnetization and electrical resistivity of polycrystalline samples around 120 K is associated with the structure distortion. Temperature-dependent magnetic susceptibility of a single crystal sample grown by NaSb flux method also exhibits a sharp transition around 120 K confirming that this anomaly is intrinsic to Na2Ti2Sb2O.

RbBiNb2O7 ceramic is synthesized by solid state reaction of stoichiometric quantities of Rb2CO3, Bi2O3, and Nb2O5 (1000 °C, 24 h) and characterized by powder XRD, Raman scattering spectroscopy, and electrical measurements.

The layered molybdenum oxide Na0.9Mo2O4 was soft-chemically exfoliated into unilamellar nanosheets, and its layer-by-layer assembled films exhibited ohmic electrical conductivity.

Two different kinds of two-dimensional (2D) materials, graphene oxide (GO) and titanium oxide nanosheets (Ti₀.₈₇O2(0.52-)), were self-assembled layer-by-layer using a polycation as a linker into a superlattice film. Successful construction of an alternate molecular assembly was confirmed by atomic force microscopy and UV-visible absorption spectroscopy as well as X-ray diffraction analysis. Exposure of the resulting film to UV light effectively promoted photocatalytic reduction of GO as well as decomposition of the polycation, which are due to their intimate molecular-level contact. The reduction completed within 3 hours, bringing about a decrease of the sheet resistance by ∼10(6). This process provides a clean and mild route to reduced graphene oxide (rGO), showing advantages over other chemical and thermal reduction processes. A field-effect-transistor device was fabricated using the resulting superlattice assembly of rGO/Ti₀.₈₇O₂(0.52-) as a channel material. The rGO in the film was found to work as a unipolar n-type conductor, which is in contrast to ambipolar or unipolar p-type behavior mostly reported for rGO films. This unique property may be associated with the electron doping effect from Ti₀.₈₇O₂(0.52-) nanosheets. A significant improvement in the conductance and electron carrier mobility by more than one order of magnitude was revealed, which may be accounted for by the heteroassembly with Ti₀.₈₇(0.52-) nanosheets with a high dielectric constant as well as the better 2D structure of rGO produced via the soft photocatalytic reduction.

The compounds Na2Ti2Pn2O (Pn = As, Sb) crystallize in the anti-K2NiF4 structure type in the space group, I4/mmm, with Z = 2 and the lattice parameters a = 4.0810(9) A and c = 15.311(3) A for the As analogue at 310 K and a = 4.160(2) A and c = 16.558(7) A for the Sb analogue at 150 K. The structure consists of edge-shared [Ti4/2Pn2O4/4]2- layers separated by double layers of Na+. These compounds exhibit an anomalous transition in the temperature-dependent magnetic susceptibility at = 330 K for the As analogue and = 120 K for the Sb analogue. Temperature-dependent powder neutron diffraction has been performed to investigate the magnetic spin ordering and structure symmetry breakdown of the compounds; however, no scattering due to magnetic spin ordering or symmetry change has been detected. The temperature-dependent electrical resistivity of these compounds also exhibits an anomaly reminiscent of CDW (charge-density-wave)/SDW (spin-density-wave) materials. The As analogue shows an insulator-to-insulator tran...

The new pnictide oxide Sr2MnZn2As2O2 is reported. The crystal structure of this compound consists of a 1:1 intergrowth of square-planar MnO22- layers and ThCr2Si2-type Zn2As22- layers interspersed by Sr cations. This compound has been prepared by sintering the stoichiometric ratio of SrO, Mn, Zn, and As in a fused-silica ampule under 0.2 atm of Ar at 1000 °C for 1 week. The sample quality has been examined by Rietveld refinement of the powder X-ray diffraction data, and the transition metal site (2a and 4d) selectivity has been analyzed by Rietveld refinement of powder neutron diffraction data. Furthermore, effects of this structural order on the magnetic susceptibility and interaction between the magnetic layers have been analyzed by temperature-dependent magnetization measurements. The magnetic structures of both phases, A2MnZn2As2O2 (A = Sr, Ba), have been investigated by temperature-dependent powder neutron diffraction. The Ba analogue exhibits two-dimensional short-range order below about 40 K, where...

The structure of Na 2 Ti 2 Sb 2 O has been investigated by temperature-dependent powder neutron diffraction. Na 2 Ti 2 Sb 2 O crystallizes in I 4/ mmm symmetry. The structure of this phase can be viewed as an anti-K 2 NiF 4 type where Ti 3+ ion is located between two oxygen atoms forming a square-planar lattice. Powder neutron diffraction studies of Na 2 Ti 2 Sb 2 O indicate that this compound has a structural distortion in the [Ti 2 Sb 2 O] 2− layer at T ≈120 K. This transition corresponds well to the previously reported anomalous transition temperature of the magnetic susceptibility and electronic resistivity. Several models to explain the data are presented and discussed.

A new mixed transition metal pnictide oxide, Ba2MnZn2As2O2, is reported. Ba2MnZn2As2O2 has been prepared in quantitative yield from heating stoichiometric amounts of BaO with the elements, which ar...

Spin-gap behavior has been observed for the first time in the layered tetragonal compound Na 2 Ti 2 Sb 2 O. Na 2 Ti 2 Sb 2 O shows a sharp discontinuity in magnetic susceptibility at 150 K, reminisent of behavior observed in the spin–Peierls compound CuGeO 3 . Na 2 Ti 2 Sb 2 O also shows a discontinuity in temperature-dependent resistivity at the magnetic transition and metallic behavior for all other temperatures, 5.7 mΩ·cm at room temperature. Ti–Sb–Ti superexchange is proposed to be favored over Ti–O–Ti superexchange, based on the high-temperature magnetic susceptibility data and on the identity of the magnetic orbitals.

Alkali-metal-ion extraction reactions using poly(tetrafluoroethylene) (PTFE; AEP reactions) were performed on two kinds of α-NaFeO(2)-type layered compounds: Na(0.68)(Li(0.68/3)Ti(1-0.68/3))O(2) and K(0.70)(Li(0.70/3)Sn(1-0.70/3))O(2). At 400 °C in flowing argon, these layered compounds were reacted with PTFE. By these reactions, alkali-metal ions in the layered compounds were successfully extracted, and TiO(2) and SnO(2) with rutile-type structure were formed. The structural similarity between the alkali-metal-ion-extracted layered compounds and the binary metal oxide products in these unique alkali-metal-ion extraction reactions was interpreted in terms of their interatomic distance distribution by atomic pair distribution function analysis. The results of this study indicate that PTFE is an effective agent to extract alkali-metal ions from layered compounds, and AEP reaction is not limited to the previously reported γ-FeOOH-type layered titania K(0.8)(Li(0.27)Ti(1.73))O(4), but is also applicable to other layered titania and other non-titanium-based layered metal oxides. Therefore, it was clarified that AEP reactions are widely applicable routes to prepare various compounds, including those that are difficult to synthesize by other reactions.