A series of perovskite compounds of La1-x-yCaxKyMnO3 was prepared by hydrothermal disproportionation reaction of MnO2. The three oxidation states of manganese(Mn3+, Mn4+ and Mn5+) can stably exist in the compounds. Under room temperature conditions, twice and three times modulated structure produced by the charge ordering can be observed by X-ray diffraction(XRD), select area electron diffraction(SAED) and high resolution transmission electron microscopy(HR-TEM). The splits of the diffraction peaks of the single crystals confirmed by synchrotron X-ray diffraction experiment are in accordance with those of the powder sample. The existence of the different oxidation states of Mn3+, Mn4+ and Mn5+ can be considered to be the dominating reason of the complicated room temperature modulated structure.
Hausmannite Mn3O4 nanoparticles were successfully prepared via a facile one-step solvothermal route with Mn(CH3COO)2·4H2O as manganese source in the mixed solvent of acetone and water.Powder X-ray diffraction(XRD),Fourier transform infrared(FTIR) spectrometry and transmission electron microscopy(TEM) were used to characterize Mn3O4 nanoparticles.It was found that the particle size could be tailored by varying the synthesis temperature.On the whole,the particle size becomes larger with the rising of solvothermal reaction temperature.But there is no linear relation between them.According to the different temperatures(60―140 °C),the average particle size is from about 9 nm to 15 nm.Magnetic properties of Mn3O4 samples prepared at 60,100 and 140 °C were studied via a superconducting quantum interference device(SQUID),respectively.
Epitaxial growth of SmFeO3/SrRuO3 was achieved on SrTiO3 substrates by the pulsed laser deposition(PLD)method at 973 K under oxygen partial pressure of 12.5 Pa.No Fe2+leakage was detected in our SmFeO3 film.The remanent polarization and coercive electric field of the thin film with a higher degree of orientation along(110)were 1.97μC/cm2 and 0.89×104 V/cm at room temperature,respectively.This film showed enhanced canted antiferromagnetism spin ordering compared with its corresponding powder materials.
The first primary organicamine templated indium iodate with the formula (H2en)KIn(IO3)6·2(H2O) was hydrothermally synthesized via reaction at 100 °C for 7 d and characterized by single-crystal X-ray diffraction and thermal analysis. The compound crystallized in a triclinic system with space group P1, a=0.69803(14) nm, b=0.70863(14) nm, c=1.2091(2) nm, α=76.417(4)°, β=79.953(4)°, γ=72.206(3)°, V=0.55012(19) nm3. Structure determination indicates that it is made up of zero-dimensional units each of which consists of [In(IO3)6]3-anion, potassium, water and ethylenediamine cation. The most striking feature of the compound is that it possesses helical hydrogen bonds formed by organic amine template, water molecules and inorganic network.
LIU Guo-zong LIU Xiao-min DING Hong NING De-kuan LI Guang-hua SHI Zhan FENG Shou-hua
以MnO2,Ca(OH)2和La(OH)3为反应原料,在惰性气氛、低温(500℃)熔融KOH体系中合成了具有菱形钙钛矿结构Ca,K共掺杂的La0.64Ca0.25K0.11MnO3纳米材料,并对Mn的价态及磁学性能等进行了讨论.X射线光电子能谱(XPS)分析结果表明,La0.64Ca0.25K0.11MnO3纳米材料中的Mn具有三重混合价态,其零场冷却低温磁化率曲线表现出顺磁-铁磁转变,居里温度(Tc)为280 K.
Thin films of perovskite manganese oxide La0.66Ca0.29K0.05MnO3(LCKMO) on Au/ITO(ITO=indium tin oxide) substrates were prepared by off-axis radio frequency magnetron sputtering and characterized by X-ray diffraction(XRD),high-resolution transmission electron microscopy(HRTEM),and conductive atomic force microscopy(C-AFM) at room temperature.The thin films with thickness ranged from100nm to300 nm basically show cubic structures with a=0.3886 nm,the same as that of the raw material used,but the structures are highly modulated.C-AFM results revealed that the atomic scale p-n junction feature of the thin films was the same as that of the single crystals.The preparation of the thin films thus further confirms the possibility of their application extending from micrometer-sized single crystals to macroscopic thin film.
HU BinHUANG Ke-keHOU Chang-minYUAN Hong-mingPANG Guang-shengFENG Shou-hua
