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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.

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.

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.

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.

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

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.

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.

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.

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.

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

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.

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.

We have designed a new approach to synthesize brookite, i.e., to extract alkali-metal ions from K0.8Ti1.73Li0.27O4 (KTLO) and to apply simultaneous heat treatment to the remaining lepidocrocite-type layers of TiO6 octahedra. For the alkali-metal ion extraction and the simultaneous heat treatment, KTLO was heated at 400 °C with polytetrafluoroethylene (PTFE) in flowing Ar. PTFE has been found to be an effective agent to extract strongly electropositive alkali-metal ions from KTLO because of the strong electronegativity of F as its component. The product of this reaction consists of a mixture of brookite, K2CO3, LiF, and PTFE derivatives, indicating the complete extraction of K+ and Li+ from KTLO and formation of brookite from the lepidocrocite-type layer of TiO6 octahedra as a template. This brookite has a partial replacement of O2− with F− and/or slight oxygen deficiency; thus, its color is light-bluish gray. Fully oxidized brookite formation and complete decomposition of PTFE derivatives have been achiev...

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...

We have designed a new approach to synthesize brookite, i.e., to extract alkali-metal ions from K(0.8)Ti(1.73)Li(0.27)O(4) (KTLO) and to apply simultaneous heat treatment to the remaining lepidocrocite-type layers of TiO(6) octahedra. For the alkali-metal ion extraction and the simultaneous heat treatment, KTLO was heated at 400 degrees C with polytetrafluoroethylene (PTFE) in flowing Ar. PTFE has been found to be an effective agent to extract strongly electropositive alkali-metal ions from KTLO because of the strong electronegativity of F as its component. The product of this reaction consists of a mixture of brookite, K(2)CO(3), LiF, and PTFE derivatives, indicating the complete extraction of K(+) and Li(+) from KTLO and formation of brookite from the lepidocrocite-type layer of TiO(6) octahedra as a template. This brookite has a partial replacement of O(2-) with F(-) and/or slight oxygen deficiency; thus, its color is light-bluish gray. Fully oxidized brookite formation and complete decomposition of PTFE derivatives have been achieved by further heating in flowing air, and coproduced alkali-metal salts have been removed by washing in water. Powder X-ray diffraction, Raman spectroscopy, and chemical analysis results have confirmed that the final brookite product treated at 600 degrees C is single phase, and it is white. The method to extract alkali-metal ions from a crystalline material using PTFE is drastically different from the common methods such as soft-chemical and electrochemical reactions. It is likely that this new synthetic approach is applicable to other layered systems to prepare a diverse family of compounds, including novel metastable ones.

Auf den Film gebannt: Eine halbtransparente und intensiv lumineszierende Monoschicht aus ausgerichteten plattchenformigen Gd2O3:0.05 Eu- Kristalliten entsteht beim Tempern der Hydroxidfilm-Vorstufe (siehe Schema). Die Photolumineszenzeigenschaften des umgewandelten Films sind deutlich besser als die des Hydroxidfilms, und sie sind viel ausgepragter als die der analogen Gd2O3:0.05 Eu-Pulverprobe.

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.

Layered rare-earth hydroxide crystallites self-assembled at the hexane/water interface were transferred to various substrates to form a monolayer film, which exhibited photoluminescence properties and ion-exchange ability.

Synthesis and crystal structure of a new compound, BaCuZn(3)As(3), are reported. Single crystals of BaCuZn(3)As(3) are synthesized via NaCl/KCl flux reaction in a sealed fused silica ampule. Its elemental composition has been determined to be Ba/Cu/Zn/As = 1.03(4):1(0):2.91(6):2.98(3), suggesting BaCuZn(3)As(3) as the chemical formula. The structure of BaCuZn(3)As(3) has been determined by X-ray diffraction. It crystallizes in the orthorhombic Cmcm space group with a = 4.2277(3) A, b = 12.970(1) A, and c = 12.011(1) A at T = 90.7 K, and it exhibits a columnar structure along the a-axis. This structure is isotypic to beta-BaCu(4)S(3) but highly distorted. beta-BaCu(4)S(3) is considered to be a layered structure whereas BaCuZn(3)As(3) is a three-dimensional network.

The dielectric properties of KCa2Nan−3NbnO3n+1 (n=3–6) Dion–Jacobson homologous series have been investigated. The dielectric constants (e) increase with the number of octahedral units (n), and the n=6 compound (KCa2Na3Nb6O19) exhibits a stable dielectric response with e=∼500 between 1 kHz and 1 MHz. This n-dependent behavior is similar to those observed in other layered perovskites such as Ruddlesden–Popper and Aurivillius phases. Raman scattering studies reveal that increase in n in KCa2Nan−3NbnO3n+1 leads to higher polarizability of the lattice and softening of the lowest-frequency phonon mode, which is responsible for the observed enhancement in e with n.