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1.
I. V. Piir M. S. Koroleva N. A. Sekushin V. E. Grass Yu. I. Ryabkov 《Russian Journal of Electrochemistry》2013,49(8):817-821
Iron-containing bismuth titanates with a cubic pyrochlore Bi1.6Fe x Ti2O7 ? δ structure were synthesized by the ceramic method. The region in which iron-containing pyrochlores are formed was determined. The pycnometric specific gravity of the samples was measured. Based on XRD and pycnometric specific gravity data, it was concluded that iron atoms lie in the bismuth sublattice. The electric properties of the materials were studied by high-temperature impedance spectroscopy. A strong effect of polarization on the impedance spectra was found. 相似文献
2.
A. G. Krasnov I. V. Piir N. A. Sekushin Ya. V. Baklanova T. A. Denisova 《Russian Journal of Electrochemistry》2017,53(8):866-872
Lithium-containing bismuth titanates with the pyrochlore-type structure Bi1.6LixTi2O7–δ were obtained for the first time. The formation of the pyrochlore phase was confirmed by X-ray diffraction analysis, scanning electron microscopy and local microanalysis. In Bi1.6MxTi2O7–δ, the lithium and indium are occupied the bismuth sites, primarily. The electrophysical properties of doped bismuth titanates were studied by impedance spectroscopy in the frequency range 1–106 Hz. In the low-temperature range (of up to ~400°C), electron conductivity predominates; above 400°C, the oxygen-ion type of conductivity is revealed. In the range p(O2) = 0.21–1 atm, the average value of the sum of ion transport numbers is 0.5 at 500–550°C. The relaxation process was found from the frequency dependences of the dielectric parameters (ε', tan δ, M''), which was of the same type for systems with different dopants (In, Li) probably due to the hopping mechanism of oxygen conductivity. 相似文献
3.
Investigation of synthesis and microstructure of bismuth titanates with TiO<Subscript>2</Subscript> rich compositions 总被引:1,自引:1,他引:0
Teresa Zaremba 《Journal of Thermal Analysis and Calorimetry》2008,93(3):829-832
Preliminary examinations regarding formation of bismuth titanates in a part of Bi2O3—TiO2 system rich with TiO2 have been carried out. Bismuth titanates have been synthesized from mixtures of Bi2O3 and TiO2 (anatase) by the conventional solid-state method at the temperatures ranged from 1273 to 1473 K. Differential thermal analysis
(DTA), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) have been used to study the formation of bismuth
titanates. The following compounds have been achieved: Bi4Ti3O12, Bi2Ti2O7 and Bi2Ti4O11. Existence of controversial bismuth titanate of formula Bi2Ti3O9 in the Bi2O3—TiO2 system has not been confirmed. 相似文献
4.
Lamia Bourja Bahcine Bakiz Abdeljalil Benlhachemi Sylvie Villain Claude Favotto 《Journal of solid state chemistry》2011,184(3):608-614
Polycrystalline samples of (1−x) CeO2−x/2 Bi2O3 phases, where x is the atom fraction of bismuth have been synthesized by the precipitation process and after the thermal treatment at 600 °C, under air. Samples are first characterized by the X-ray diffraction and scanning electron microscopy. To determine the samples specific surface areas, Brunauer-Emmett-Teller (BET) analyses have been performed. In the composition range 0≤x≤0.20, a cubic solid solution with fluorite structure is obtained. For compositions x comprised between 0.30 and 0.90, two types of T′ (or β′) and T (or β) tetragonal phases, similar to the well-known β′ or β Bi2O3 metastable structural varieties, are observed. However, the crystal cell volumes of these β′ or β Bi2O3 phases increase with the composition x in bismuth: this might be due to the presence of defects or substitution by cerium atoms, in the tetragonal lattices. Using X-ray diffraction profile analyses, correlations between bismuth composition x and crystal sizes or lattice distortions have been established. The solid-gas interactions between these polycrystalline materials and air-CH4 and air-CO flows have been studied as a function of temperature and composition x, using Fourier transform infrared (FTIR) analyses of the conversions of CH4 and CO gases into the CO2 gas. The transformations of CH4 and CO molecules as a function of time and temperature are determined through the intensities of FTIR CO2 absorption bands. Using the specific surface areas determined from BET analyses, these FTIR intensities have been normalized and compared. For all bismuth compositions, a low catalytic reactivity is observed with air-CH4 gas flows, while, for the highest bismuth compositions, a high catalytic reactivity is observed with air-CO gas flows. 相似文献
5.
The structure of K-bearing tantalate pyrochlore (K2-xGdx)Ta2O6+x(x∼0.4) was studied at high pressures using in situ X-ray diffraction and Raman scattering methods. Experimental results indicated that (K2-xGdx)Ta2O6+x(x∼0.4) retains the pyrochlore structure up to 40 GPa, but partial amorphization occurred at pressures above 23 GPa. The amorphous phase was also confirmed in the quenched sample by means of transmission electron microscopy. The tantalate pyrochlore lattice is more stable than pyrochlore compounds in other systems, such as rare earth titanates, zirconates and stannates. The structural stability of pyrochlore tantalate may be mainly related to the size ratio of cations on the 16d and 16c sites in the lattice. 相似文献
6.
Bismuth Zinc Borate glasses with compositions xBi2O3–30ZnO–(70 − x)B2O3 (where x = 30, 35, 40 and 45 mol %) have been prepared by melt quenching method. These glasses were characterized by X-ray diffraction (XRD), Differential Thermal Analysis (DTA), Fourier Transform Infrared Spectrometer (FTIR) and Broad Band Dielectric Spectrometer (BDS). DTA and FTIR analysis reveals that Non-Bridging Oxygens (NBOs) increase with increase of bismuth content in the glass. Electrical data have been analyzed in the framework of impedance and modulus formalisms. The activation energy for dc conductivity decreases with increase of bismuth concentration. The imaginary part of modulus spectra has been fitted to non-exponential Kohlrausch–Williams–Watts (KWW) function and the value of the stretched exponent (β) is found to be almost independent of temperature but slightly dependent on composition. 相似文献
7.
E. S. Buyanova Yu. V. Emel’yanova M. V. Morozova A. A. Krylov I. V. Nikolaenko 《Russian Journal of Inorganic Chemistry》2018,63(10):1297-1302
Design of composites is a way to improve the quality of solid electrolytes. By mechanically mixing and annealing substituted bismuth vanadate with nanosized aluminum, bismuth, and zirconium binary oxides, we obtained heterogeneous materials Bi4V1.7Fe0.3O11 – δ/xAl2O3, Bi4V1.7Fe0.3O11 – δ/xBi2O3, and Bi4V1.7Fe0.3O11 – δ/xYSZ. The investigation tools were X-ray powder diffraction and electron microscopy with energy-dispersive microanalysis. The composition of materials was studied, the non-interaction of components was elucidated in the aluminum oxide and zirconium oxide composite series, and a nonuniform distribution of nanopowder particles across the surfaces and cleaves of sinters was discovered. The bismuth atoms from bismuth oxide were shown to be capable of incorporating into the Bi4Fe0.3V1.7O11 – δ structure. The charge transport characteristics of the materials were studied by impedance spectroscopy. No changes were observed in logσ–103/T trends in composites with various binary oxides and various oxide contents. An increase in binary oxide concentration was shown to give rise to an insignificant decay in electrical conductivity. 相似文献
8.
Z. A. Mikhaylovskaya E. S. Buyanova S. A. Petrova M. V. Morozova N. V. Tarakina M. V. Kuznetsov 《Russian Journal of Inorganic Chemistry》2017,62(11):1441-1449
The work is devoted to the synthesis and attestation of a number of substituted vanadates and chromates of bismuth. For bismuth vanadates of the BIMEVOX family, the homogeneity regions of the Bi4V2 – xCr x O11 ± d solid solutions have been refined, the features of the structure change of the compounds with increasing chromium content and changing temperature have been noted, and the powders and ceramics have been studied by electron microscopy. For the first time, as an impurity, an individually substituted bismuth chromate of the composition Substituted bismuth chromate of the Bi13Cr5 – yV y O34.5 – d (y = 0.95 ± 0.05) composition has been detected for the first time as an impurity and synthesized as an individual compound, which has been characterized by X-ray diffraction, electron microscopy, chemical analysis, and photoelectron spectroscopy data; its homogeneity range has been determined, and electroconductive characteristics have been studied. 相似文献
9.
The V5+/Nb5+-substituted lithium lanthaum titanates are synthesized by a conventional solid-state reaction method at high temperature in air. The structural and conductivity studies of the obtained perovskite oxide samples are investigated by x-ray diffraction (XRD), SEM, and impedance spectroscopy. From the powder XRD patterns, it is clearly observed that the synthesized samples exhibit a well-defined cubic structure with the Pm3m (Z = 1) space group. The lattice parameter is decreased with increasing vanadium content in Li0.5?x La0.5Ti1?x V x O3, but increased with the increasing niobium content in Li0.5?x La0.5Ti1?x Nb x O3. The scanning electron microscope measurements confirmed that these materials consist of fairly ordered grains throughout the surface area. The conductivity variations with the substitution of vanadium/niobium are also reported. The bulk ionic conductivity measured in the temperature range from room temperature to 150 °C is about the same as reported earlier for the related lithium lanthanum titanate. However, the low activation energies for ionic conduction observed for these samples encourage further investigations for better conductors in this system. 相似文献
10.
Yu. V. Emel’yanova Z. A. Mikhailovskaya E. S. Buyanova S. A. Petrova 《Russian Journal of Applied Chemistry》2017,90(3):354-360
Results are reported of a study of the structural and electrical characteristics of substituted bismuth niobates with composition Bi3Nb1–x Er x O7–δ, which are promising oxygen-ion conductors. The homogeneity regions of solid solutions were determined by X-ray phase analysis and electron microscopy with X-ray fluorescence microanalysis, and their crystal-chemical parameters were calculated. The electrical conductivity of sintered samples was examined by impedance spectroscopy. 相似文献
11.
《Comptes Rendus de l''Academie des Sciences Series IIB Mechanics Physics Astronomy》2001,4(11):845-848
7Li nuclear magnetic resonance relaxation times, T1 and T1ρ, versus temperature are reported in the 150–900 K temperature range on the lithium lanthanum titanates, Li3xLa2/3–x□1/3–2xTiO3, which are fast ionic conductors. Two characteristic frequencies of Li+ motions are evidenced in these compounds: the first is in the range of the Larmor frequency when the second one is in the range of the radio-frequency field. These frequencies are respectively attributed to motion of the Li+ ion inside the cage formed by the oxygen ions and to jumps between the cages. The T1 and T1ρ studies on 6Li nuclei confirm the above results and show that the relaxation is not due to quadrupolar interaction at a variance, which is generally accepted. 相似文献
12.
《Journal of solid state chemistry》1987,66(2):311-317
New substituted copper titanates with the CaCu3Ti4O12 perovskite-like structure were synthesized and characterized. Their formula is Li|Cu3−xLix| |Ti3−xMV1+x|O12. There is a homogeneity range for MV = Nb, 0.12 ≤ x ≤ 0.33, and a unique composition for MV = Ta, x = 0.33. The unit cell is cubic: a ∼ 2ap (parameter of the ideal cubic cell) ∼ 7.40 Å. The CaCu3Ti4O12-type structure was confirmed from an X-ray powder structural determination. Lithium occupies both square planar sites where it replaces copper and icosahedral sites, with a probable delocalization. Crystal chemistry of the AC3B4O12 structure is considered, taking into account the evolution of anion packing and the distortion of polyhedra. A diagrammatic representation is proposed so that precise information on the regularity of the C3B4O12 network can be obtained. 相似文献
13.
Z. A. Mikhailovskaya E. S. Buyanova S. A. Petrova V. M. Zhukovskii 《Russian Journal of Electrochemistry》2013,49(7):658-664
The possibility of synthesizing oxygen-ionic conductors from substituted bismuth molybdates containing [Bi12O14] n 8n+ columns, MoO4 tetrahedra, and isolated Bi ions in their structure was studied. The specifics of their structure and electric conductivity were investigated. The general formula of the solid solutions can be recorded as Bi13Mo5 ? x Me x O34 ? δ, where Me is the fouror five-valent d metal (Ti, Zr, V, Nb). The electric conductivity of doped bismuth molybdates considerably increased compared with that of the matrix compound. The electric conductivity reached 5.5 × 10?3 S cm?1 at 700°C and 1.8 × 10?4 S cm?1 at 350°C for the zirconium-doped compound with x = 0.4. The porosity of the ceramics was less than 5%; the thermal expansion coefficient was of the order of 14 × 10?6 K?1. Based on the set of their characteristics, these compounds are recommended as materials for membranes of electrochemical devices. 相似文献
14.
《Solid State Sciences》2000,2(5):525-529
Crystallographic and low frequency dielectric studies were performed on new lead-free ceramics derived from BaTiO3 by cationic substitutions in the 12 C.N. crystallographic site and having the composition Ba1−xKx/2Lax/2TiO3 or Ba1−xA2x/3TiO3 (A=La, Bi). A classical ferroelectric behaviour was shown for compositions close to BaTiO3, while a relaxor one occured when the composition deviated from BaTiO3. In any case, the value of TC (or Tm) and the relaxor characteristics are higher as x increases. Concerning potassium-free ceramics, bismuth compositions compared with lanthanum ones favoured both high ferroelectric and relaxor characteristics due to the lone pair of Bi3+. Such new materials are of interest for environmental friendly applications. 相似文献
15.
C.E. Bamberger H.W. Dunn G.M. Begun S.A. Landry 《Journal of solid state chemistry》1985,58(1):114-118
The formation of solid solutions Ln2?xBixTi2O7, where Ln = La to Lu and Y, except Ce, Pm, and Eu, has been studied by Raman spectroscopy and to a lesser extent by X-ray diffraction. It has been established that the solubility of bismuth increases with decreasing ionic radius of the lanthanide element. No evidence was experimentally found in this work for the existence of Bi2Ti2O7. 相似文献
16.
Zhichao Shan Wendeng Wang Hanming Ding Fuqiang Huang 《Journal of solid state chemistry》2008,181(6):1361-1366
The layered compound of lead bismuth oxybromide PbBiO2Br, prepared by conventional solid-state reaction method, has an optical band gap of 2.3 eV, and possesses a good visible-light-response ability. The references, PbBi2Nb2O9, TiO2−xNx, BiOBr and BiOI0.8Cl0.2, which are excellent visible-light-response photocatalysts, were applied to comparatively understand the activity of PbBiO2Br. Degradation of methyl orange and methylene blue was used to evaluate photocatalytic activity. The results show that PbBiO2Br is more photocatalytically active than PbBi2Nb2O9, TiO2−xNx and BiOBr under visible light. 相似文献
17.
Shreyashi Ganguly Chen Zhou Donald Morelli Jeffrey Sakamoto Ctirad Uher Stephanie L. Brock 《Journal of solid state chemistry》2011,184(12):3195-3201
Heterogeneous nanocomposites of p-type bismuth antimony telluride (Bi2−xSbxTe3) with lead telluride (PbTe) nanoinclusions have been prepared by an incipient wetness impregnation approach. The Seebeck coefficient, electrical resistivity, thermal conductivity and Hall coefficient were measured from 80 to 380 K in order to investigate the influence of PbTe nanoparticles on the thermoelectric performance of nanocomposites. The Seebeck coefficients and electrical resistivities of nanocomposites decrease with increasing PbTe nanoparticle concentration due to an increased hole concentration. The lattice thermal conductivity decreases with the addition of PbTe nanoparticles but the total thermal conductivity increases due to the increased electronic thermal conductivity. We conclude that the presence of nanosized PbTe in the bulk Bi2−xSbxTe3 matrix results in a collateral doping effect, which dominates transport properties. This study underscores the need for immiscible systems to achieve the decreased thermal transport properties possible from nanostructuring without compromising the electronic properties. 相似文献
18.
A. I. Klyndyuk E. A. Tugova O. N. Karpov E. A. Chizhova M. V. Tomkovich V. M. Kononovich 《Russian Journal of General Chemistry》2016,86(10):2282-2287
The sequence of phases appearance during the formation of Bi1–xNdxFeO3 solid solutions in powder oxides mixtures of bismuth, neodymium, and iron has been determined. It has been shown that the closeness of the reaction mixture composition to that of the individual compound (BiFeO3 or NdFeO3) is essential for the realization of the series of phase transformations yielding solid solutions of multiferroics Bi1–xNdxFeO3 as the final product, due to the prevalence of various interphase contacts in the starting reaction zone. 相似文献
19.
Nan Yang Yan An JiWen Cai LiHong Hu YiBo Zeng ZongWan Mao GuanHua Chen HongZhe Sun 《中国科学:化学(英文版)》2010,53(10):2152-2158
Four bismuth complexes, (H2En)[Bi2(cit)2(H2O)4/3]·(H2O) x (1), (H2En)3[Bi2(cit)2Cl4]·(H2O) x (2), (HPy)2[Bi2(cit)2(H2O)8/5]·(H2O) x (3) and (H2En)[Bi2(cit)2](H2O) x (4) [cit = citrate4?; En = ethylenediamine; Py = pyridine] have been synthesized and crystallized. The crystal structures reveal that the basic building blocks in all of these complexes are bismuth citrate dimeric units which combine to form polymeric architectures. The embedded protonated ethylenediamine and pyridine moieties in the polymeric frameworks have been identified by X-ray crystallography and solid-state cross polarization/magic angle spinning (CP/MAS) 13C NMR. Based on the framework of complex 1, a structural model of a clinically used antiulcer drug, ranitidine bismuth citrate (RBC) was generated. The behavior of the protonated amine-bismuth citrate complexes in acidic aqueous solution has been studied by electrospray ionization-mass spectrometry (ESI-MS). 相似文献
20.
John W. Medernach 《Journal of solid state chemistry》1975,15(4):352-359
The bismuth oxide films evaporated from bulk Bi2O3 are shown to vary in stoichiometry. The as-evaporated low rate (1–5 Å/sec) films are microcrystalline and bismuth rich, relative to Bi2O3, and their optical absorption edge broadens and shifts to lower energies. High rate (15–25 Å/sec) films are morphous and oxygen-rich with an absorption edge shifted to higher energies. Thermal decomposition of the Bi2O3 during evaporation produces the variations in film stoichiometry. The high temperature δ-Bi2O3 observed in the as-evaporated low rate films and thermally treated amorphous films indicates the melt and the films are structurally similar. Thermal treatment of the low rate films results in the formation of the β-form. Comparison of X-ray and stoichiometry results suggests that β-Bi2O3 be expressed as β-Bi2O±3x, where x is the deviation from trioxide stoichiometry. 相似文献