Space Group R3m Research Articles

Florencite-(Sm)—(Sm,Nd)Al3(PO4)2(OH)6: A new mineral species of the alunite-jarosite group from the subpolar urals

Florencite-(Sm), a new mineral species of the florencite subgroup, was found in association with xenotime-(Y) in quartz veins of the Maldynyrd Range of the Subpolar Urals as thin zones within rhombohedral crystals of florencite-(Ce) with faceting by \(\{ 01\bar 11\} \) and \(\{ 10\bar 12\} \). The thickness of particular florencite-(Sm) zones is 0.01–0.1 mm, and the total thickness of a series of such zones is 1–3 mm. Florencite-(Sm) is colorless and pale pink or pale yellow with white streaks; its Mohs hardness is 5.5–6.0. Its measured and calculated densities are 3.70 and 3.743 g/cm3, respectively. The mineral is transparent, nonpleochroic, and uniaxial (positive), and ω = 1.704(2) and ɛ = 1.713(2). The electron beam’s fluorescence spectrum was 592 nm (intense green luminescence of Sm3+) and 558 nm (yellow luminescence of Nd3+). The chemical composition was as follows (microprobe, average of 2 WDS, wt %): 0.62 La2O3, 3.29 Ce2O3, 1.05 Pr2O3, 10.31 Nd2O3, 12.62 Sm2O3, 0.41 Eu2O3, 2.30 Gd2O3, 0.13 Dy2O3, 0.71 SrO, 0.35 CaO, 29.89 Al2O3, 26.14 P2O5, 0.85 SO3, 0.09 SiO2, 88.76 in total; 10.74 H2O (meas.). The empirical formula based on 14 oxygen atoms is (Sm0.38Nd0.32Gd0.07Ce0.10Pr0.03La0.02Eu0.01Sr0.04Ca0.03)1.0Al3.04(P1.91S0.05Si0.01)1.97O14H5.92. The idealized formula is (Sm,Nd)Al3(PO4)2(OH)6. Mineral is trigonal, space group R3m, a = 6.972(4), c = 16.182(7) A, V = 681.2 A3, Z = 3. The XRD pattern is as follows: dln (I) (hkl): 2.925 (10) (113), 1.881 (6) (303), 2.161 (5) (107), 5.65 (4) (101), and 3.479 (4) (110). The IR spectrum: 466, 510, 621, 1036, 1105, 1223, 2957, and 3374 cm−1.

Jichengite 3CuIr2S4·(Ni, Fe)9S8, a New Mineral, and Its Crystal Structure

Abstract:A new mineral, jichengite ideally 3CuTr2S4·(Ni,Fe)9S8, was found as a constituent of placer concentrates at a branch of the Luanhe River, about 220 km NNE of Beijing. Its associated minerals are chromite, magnetite, ilmenite, zircon, native gold, iridium, ferrian platinum and osmium. The placer is distributed at places around ultrabasic rock, which hosts chromite orebodies, from which PGM originated. Jichengite occurs commonly as massive or granular aggregates. No perfect morphology of jichengite was observed. It is steel gray and opaque with metallic luster and black streak. It has a Mohs hardness of 5, VHN (d) μm 21.65, Hm 4.465, Hv = 268.1 N/um2. It is brittle and weakly magnetic. Cleavage {010} is rarely observed. No fracture was observed. Density could not be measured because of its too small grain size. Density (calc.) is 7.003 g/cm3. Reflect light is reddish‐brown, without internal reflections. Anisotropism is distinct with grayish or yellowish white in crossed nicols and bluish violet‐copper red in uncrossed nicols. Jichengite shows weak pleochroism and strong bireflectance. The reflectance values in air at the Standard Commission on Ore Mineralogy wavelengths are: 38.9, 34.3 at 470 nm, 38.9, 34.5 at 546 nm, 39.1, 35.3 at 590 nm, 39.2, 36.8 at 650 nm, parallel‐axial extinction. The six strongest lines in the X‐ray powder‐diffraction pattern [d in Å, (I), (hkl)] are: 3.00 (100) (116), 2.80 (50) (205), 2.48. (50) (208), 1.916 (40) (2, 1, 10), 1.765 (60) (220), 1.753 (50) (2, 0, 16). Five chemical analyses carried out, yielding the following results: S 25.76 (25.49–5.97), Fe 10.03 (9.78–10.31), Co 0.78 (0.75–0.81), Ni 12.48 (12.32–12.85), Cu 4.77 (4.69–1.83), Ir 46.98(46.14–17.89), sum 100.80wt%, which produced a formula (Cu1.556Fe0.976)2.532(Ir5.063S10.126)·(Fe2.7451Ni4.404Co0.273)7.422S6.517. The ideal formula is X10Ir5S17.5, which was calculated by single crystal structure analyses, where X = Cu(II) + Fe(II) + Ni(II) + Co(II). The single crystal data were collected using a diffractometer with Mo Kα radiation and a graphite monochromate. The crystal system is trigonal with space group R3m and unit cell parameters a=7.0745(14) Å, c=34.267(10) Å (The superstructure not found), and the final R Indices [with 564 observed reflections, I>2sigma (I)] are R1=0.0495, wR2=0.1349. The specimens are deposited in the Geological Museum of China.

Jichengite 3CuIr2S4·(Ni, Fe)9S8, a New Mineral, and Its Crystal Structure

A new mineral, jichengite ideally 3CuTr2S4·(Ni,Fe)9S8, was found as a constituent of placer concentrates at a branch of the Luanhe River, about 220 km NNE of Beijing. Its associated minerals are chromite, magnetite, ilmenite, zircon, native gold, iridium, ferrian platinum and osmium. The placer is distributed at places around ultrabasic rock, which hosts chromite orebodies, from which PGM originated. Jichengite occurs commonly as massive or granular aggregates. No perfect morphology of jichengite was observed. It is steel gray and opaque with metallic luster and black streak. It has a Mohs hardness of 5, VHN (d) μm 21.65, Hm 4.465, Hv = 268.1 N/um2. It is brittle and weakly magnetic. Cleavage {010} is rarely observed. No fracture was observed. Density could not be measured because of its too small grain size. Density (calc.) is 7.003 g/cm3. Reflect light is reddish-brown, without internal reflections. Anisotropism is distinct with grayish or yellowish white in crossed nicols and bluish violet-copper red in uncrossed nicols. Jichengite shows weak pleochroism and strong bireflectance. The reflectance values in air at the Standard Commission on Ore Mineralogy wavelengths are: 38.9, 34.3 at 470 nm, 38.9, 34.5 at 546 nm, 39.1, 35.3 at 590 nm, 39.2, 36.8 at 650 nm, parallel-axial extinction. The six strongest lines in the X-ray powder-diffraction pattern [d in Å, (I), (hkl)] are: 3.00 (100) (116), 2.80 (50) (205), 2.48. (50) (208), 1.916 (40) (2, 1, 10), 1.765 (60) (220), 1.753 (50) (2, 0, 16). Five chemical analyses carried out, yielding the following results: S 25.76 (25.49–5.97), Fe 10.03 (9.78–10.31), Co 0.78 (0.75–0.81), Ni 12.48 (12.32–12.85), Cu 4.77 (4.69–1.83), Ir 46.98(46.14–17.89), sum 100.80wt%, which produced a formula (Cu1.556Fe0.976)2.532(Ir5.063S10.126)·(Fe2.7451Ni4.404Co0.273)7.422S6.517. The ideal formula is X10Ir5S17.5, which was calculated by single crystal structure analyses, where X = Cu(II) + Fe(II) + Ni(II) + Co(II). The single crystal data were collected using a diffractometer with Mo Kα radiation and a graphite monochromate. The crystal system is trigonal with space group R3m and unit cell parameters a=7.0745(14) Å, c=34.267(10) Å (The superstructure not found), and the final R Indices [with 564 observed reflections, I>2sigma (I)] are R1=0.0495, wR2=0.1349. The specimens are deposited in the Geological Museum of China.

Phase transition and electrical properties of PbMg 1/3Nb 2/3O 3-BiFeO 3 solid-solution

A solid-solution of PbMg 1/3Nb 2/3O 3-BiFeO 3 (60:40) was prepared by a high-temperature solid-state reaction technique. Rietveld structural analysis using high-resolution X-ray diffraction data/pattern of the above system unfolds a rhombohedral crystal structure with R3m space group. Detailed studies of dielectric properties of the material in wide temperature range (30–420 °C) exhibit a dielectric anomaly at 300 °C which may be related to the magnetic transition. Increase in relative permittivity above this transition temperature is supported by thermally activated transport of oxygen vacancies and hopping of electrons. The temperature response of ac conductivity in this material is found to be governed by the motion of ionized oxygen vacancies, polarons and lead (Pb) vacancies.

Elaboration and Characterization of New Pseudo-Binary Hydride-Forming Phases Pr1.5Mg0.5Ni7 and Pr3.75Mg1.25Ni19: A Comparison to the Binary Pr2Ni7 and Pr5Ni19 Ones

New pseudobinary phases have been synthesized in the ternary system Pr–Mg–Ni. The Pr1.5Mg0.5Ni7 compound is obtained as a pure phase, but it exists under two polymorphic structures: hexagonal Ce2Ni7-type (2H; space group P63/mmc) and rhombohedral Gd2Co7-type (3R; space group R3m). The Pr3.75Mg1.25Ni19 compound is found in equilibrium with the PrNi5-type secondary phase, and it adopts also two polymorphic structures: hexagonal Sm5Co19-type (2H; space group P63/mmc) and rhombohedral Ce5Co19-type (3R; space group R3m). The crystallographic structures as well as the thermodynamic properties of these hydrogen-absorbing compounds have been determined and are compared to those of the binary compounds Pr2Ni7 and Pr5Ni19. The two compounds are able to form hydrides at room temperature, in the pressure range of 0–10 MPa. The replacement of 25 at. % of the rare earth by magnesium for both stoichiometries leads to an increase of the weight capacity and a decrease of the equilibrium pressures with the formation of w...

New Ternary and Quaternary Barium Nitride Halides; Synthesis and Crystal Chemistry

New ternary and quaternary nitride halides, Ba(2)N(X,X') (X = F, Cl, Br; X' = Br, I), have been synthesized from the high temperature reactions of barium subnitride with the respective barium halides under an inert atmosphere. The former include the first fully characterized barium nitride halides for X other than F, and the latter are the first examples of barium nitride mixed halides. The variation in structure with composition has been investigated by powder X-ray and powder neutron diffraction techniques. The heavier ternary and quaternary nitride halides (X, X' = Cl, Br, I) crystallize in the hexagonal space group R3m, with the anti-α-NaFeO(2) structure. Ba(2)NF forms with both an anti-α-NaFeO(2) structure, in which N(3-) and F(-) are ordered and an anion-disordered simple rock salt structure. The hexagonal polymorph of Ba(2)NF is the only example to date of a nitride fluoride adopting this layered structure. Both the ternary and the quaternary compounds display very weak, temperature independent paramagnetism.

Ferroelectric and antiferrodistortive phase transition in the multiferroic (Bi0.8Ba0.2)(Fe0.8Ti0.2)O3: A high temperature neutron powder diffraction study

Presented here are the results of Rietveld analysis of powder neutron diffraction data, which reveal that both the ferroelectric and antiferrodistortive phase transitions occur together at T ∼ 925 K during heating, leading to a change in crystal structure from room temperature rhombohedral phase in the R3c space group with tilted oxygen octahedra to the high temperature paraelectric and paraelastic cubic phase in Pm3−m space group. The presence of superlattice peaks due to antiphase rotation of oxygen octahedra in the rhombohedral phase until the transition to the cubic phase precludes the possibility of an intermediate R3m space group, conjectured previously on the basis of an x-ray powder diffraction study. Discontinuous change in the unit-cell volume, tilt angle, and bond lengths at the transition temperature TC, and phase coexistence of R3c and Pm3−m over 100 K range across TC, suggest that the transition is of first order. It is argued that the R3c to Pm3−m phase transition is of trigger type involving simultaneous condensation of Γ4- and R4+ modes.

Simple Guanidinium Salts Revisited: Room–Temperature Ferroelectricity in Hydrogen-Bonded Supramolecular Structures

Dielectric, calorimetric, and X-ray diffraction methods have been employed to characterize the crystals of guanidinium tetrafluoroborate and guanidinium perchlorate, both built of two-dimensional honeycomb hydrogen-bonded sheets. The room-temperature ferroelectricity of these isosymmetric complexes (space group R3m) has been evidenced by the polarization switching in an external electric field and pyroelectric effect. The analysis of structural data as a function of temperature showed that the high values of spontaneous polarization of about 8.5 μC cm(-2) originate mainly from the ionic displacements, while the exceptional thermally induced increase of polarization is related with the apparent weakening of the N-H···F/N-H···O hydrogen bonds at elevated temperatures. An excellent correlation between the donor-acceptor distance and the relative displacement of the ions in the crystal lattice along the polar direction has been found. The huge entropy change at the two-closely spaced high-temperature phase transitions in guanidinium perchlorate, together with the large crystal polarization, suggest a large electrocaloric effect, the property strongly desired for solid-state cooling applications.

Hydrothermal Synthesis and Crystal Structures of Two Novel Acentric Mixed Alkaline Earth Metal Berylloborates Sr3Be2B5O12(OH) and Ba3Be2B5O12(OH)

The synthesis and structure of the isostructural acentric compounds Sr(3)Be(2)B(5)O(12)(OH) (1) and Ba(3)Be(2)B(5)O(12)(OH) (2) are reported for the first time. These compounds crystallize in the space group R3m, and the unit cell parameters are a = 10.277(15) Å and c = 8.484(17) Å for 1 and a = 10.5615(15) Å and c = 8.8574(18) Å for 2. The structures consist of a network of [Be(2)B(4)O(12)(OH)] units interwoven with a network consisting of MO(9) polyhedra (M = Sr, Ba) and BO(3) triangles and exemplify how acentric building blocks such as [BO(3)](3-), [BO(4)](5-), and [BeO(4)](6-) can be especially suitable to build noncentrosymmetric long-range structures. Both networks are centered on the 3-fold rotation axis and present themselves in alternating fashion along [001]. Acentricity is imparted by the alignment of the polarities of BO(3) and BeO(4) environments. Infrared spectroscopy has been used to confirm the local geometries of B and Be, as well as the presence of hydroxide in the crystal structure. Another interesting feature of these compounds is the presence of disorder involving Be and B at the tetrahedral Be site. The degree of the disorder has been confirmed by observing a noticeable shortening of average Be-O bond distances.

A novel flower basket-shaped organosilyl derivative based on trivacant tungstosilicate: [(C4H9)4N]3H[α-A-SiW9O34(CH3SiO)6]·3H2O

Abstract A novel hexasubstituted organosilyl derivative based on trivacant tungstosilicate [(C4H9)4N]3[α-A-SiW9O34(CH3SiOH)6]·3H2O (1), was synthesized under phase-transfer conditions, by the reaction of the CH3SiHCl2 with Na10[α-SiW9O34]∙18H2O, which was characterized by IR spectrum, elemental analyses and X-ray single crystal diffraction. X-ray structural analysis reveals that 1 crystallizes in hexagonal space group R3m, with lattice constants a = 26.0333(2) A, b = 26.0333(2) A, c = 13.7239(2) A, V = 8055.02(15) A3, and Z = 3, which consists of a trivacant Keggin moiety [α-A-SiW9O34]10−, on which six {CH3Si } groups are grafted via six Si O W bridges, and that each of the six {CH3Si } groups links with two adjacent ones through Si O Si bridges resulting in a unique flower basket-shaped polyoxoanion framework.

Syntheses, crystal structures, magnetic properties and vibrational spectra of nitridoborate-halide compounds Sr2[BN2]Br and Eu2[BN2]X(X= Br, I) with isolated [BN2]3–units

AbstractThe title compounds Sr2[BN2]Br (1), Eu2[BN2]Br (2) and Eu2[BN2]I (3) were obtained from reactions of mixtures of Sr3[BN2]2and SrBr2(1) and the binaries EuN, h-BN and EuX2(X= Br, I) (2,3), respectively. The crystal structure of Sr2[BN2]Br was solved from X-ray powder diffraction data and those of the europium compounds from X-ray single crystal data. Sr2[BN2]Br and Eu2[BN2]Br are isotypic crystallizing in the rhombohedral space groupR-3m(No. 166, Pearson code:hR18;Z= 3;a= 4.11692(2) Å,c= 26.4611(2) Å (1);a= 4.0728(3) Å,c= 26.589(3) Å (2)). The crystal structures are built up by layers of condensed edge-sharing [B—N—B]@Eu6and [Br]@Eu6trigonal antiprisms, which are alternately stacked along [001]. Eu2[BN2]I – isotypic to Sr2[BN2]I – crystallizes in the monoclinic space groupP21/m(No. 11, Pearson code:mP24;Z= 4;a= 10.2548(6) Å,b= 4.1587(3) Å,c= 13.1234(9) Å,β= 91.215(4)°). The crystal structure is characterized by slightly puckered layers formed by condensed edge sharing I@Eu6octahedra which are separated by isolated [BN2]3–units. The bond lengths for the strictly linear [BN2]3–anions in(1)and(2)ared(B—N) = 1.351(4) Å and 1.356(8) Å, respectively. In Eu2[BN2]I two crystallograhically distinct [BN2]3–anions are present withd(B1—N) = 1.32(4) Å, 1.37(4) Å andd(B2—N) = 1.30(4) Å, 1.34(4) Å, respectively. Their bond angles vary slightly: ∠(N—B1—N) = 179(3)° and ∠(N—B2—N) = 177(3)°. The magnetic susceptibility data of the europium compounds (2) and (3) indicate that the Eu ions are divalent with 4f7configuration. Vibrational spectra were measured and interpreted based on theD∞hsymmetry of the discrete linear [N—B—N]3–moieties, considering the site symmetry reduction and the presence of two distinct [BN2]3–groups in (3).

K3B6O10Cl: A New Structure Analogous to Perovskite with a Large Second Harmonic Generation Response and Deep UV Absorption Edge

Introduction of the Cl(-) anion in the borate systems generates a new perovskite-like phase, K(3)B(6)O(10)Cl, which exhibits a large second harmonic response, about four times that of KH(2)PO(4) (KDP), and is transparent from the deep UV (180 nm) to middle-IR region. K(3)B(6)O(10)Cl crystallizes in the noncentrosymmetric and rhombohedral space group R3m. The structure consists of the A-site hexaborate [B(6)O(10)] groups and the BX(3) Cl-centered octahedral [ClK(6)] groups linked together through vertices to form the perovskite framework represented by ABX(3).

Improved Thermoelectric Properties of (GeTe)90(Ag y Sb2−y Te3−y )10 by Tuning the Ag-to-Sb Ratio

(GeTe)90(Ag y Sb2−y Te3−y )10 (y = 0.6, 0.7, 0.8, 1.0) compounds were prepared by combining melting and hot pressing, and the thermoelectric properties were studied over the temperature range of 300 K to 770 K. Powder x-ray diffraction results revealed that all the samples were the rhombohedral phase with space group R3m. The electrical conductivity of samples decreased with temperature, while the Seebeck coefficient increased. The thermal conductivity of all the samples was very low, especially for those with the lower y values. High ZT values above 1.6 were obtained for the samples with y = 0.6, 0.7, and 0.8.

A New Phase in the Binary Iron Nitrogen System?—The Prediction of Iron Pernitride, FeN2

Among numerous different AB(2) structures with the hypothetical composition FeN(2), the structures lying lowest in energy have been determined by a series of density-functional electronic-structure calculations. The most likely FeN(2) phase crystallizing in the space group R3m must be considered an iron pernitride incorporating binuclear N-N units (d=1.275 Å) with an anionic charge of 2-. This high-pressure magnetic phase with a bulk modulus of about 192 GPa and an iron saturation moment of approximately 1.68 μ(B) should already form at a pressure of 17 GPa at an assumed reaction temperature of 1000 K. Besides bonding Fe-N interactions, antibonding N-N and Fe-Fe interactions exist in the crystal structure.

Crystal growth and optical properties of a noncentrosymmetric haloid borate, K3B6O10Br

A high quality single crystal of K3B6O10Br has been grown with sizes up to 14 × 12 × 7 mm3 by the top-seeded solution growth method. It crystallizes in a noncentrosymetric trigonal system, space groupR3m with cell parameters a = 10.1153(8) A, c = 8.8592(14) A, Z = 3, V = 785.02(15) A3. K3B6O10Br has a three-dimensional network consisting of B6O13 units, which are surrounded by a K–Br framework. A transmission spectrum of the K3B6O10Br crystal was reported. Its refractive indices were measured by a minimum deviation technique and fit to Sellmeier equations. Nonlinear optical measurements demonstrate that the material has second harmonic generation properties, with efficiency approximately three times that of KH2PO4.

Evolving morphotropic phase boundary in lead-free (Bi1/2Na1/2)TiO3–BaTiO3 piezoceramics

The correlation between structure and electrical properties of lead-free (1−x)(Bi1/2Na1/2)TiO3–xBaTiO3 (BNT-100xBT) polycrystalline piezoceramics was investigated systematically by in situ synchrotron diffraction technique, combined with electrical property characterization. It was found that the morphotropic phase boundary (MPB) between a rhombohedral and a tetragonal phase evolved into a morphotropic phase region with electric field. In the unpoled material, the MPB was positioned at the transition from space group R3m to P4mm (BNT-11BT) with optimized permittivity throughout a broad single-phase R3m composition regime. Upon poling, a range of compositions from BNT-6BT to BNT-11BT became two-phase mixture, and maximum piezoelectric coefficient was observed in BNT-7BT. It was shown that optimized electrical properties are related primarily to the capacity for domain texturing and not to phase coexistence.

Synthesis and Crystal Structure of Nb0.84N

A new compound of the composition Nb0.84N was prepared by ammonolysis of NbO2 at 1100 °C. The crystal structure refinement was performed by the Rietveld method using X-ray and neutron powder diffraction data. Nb0.84N crystallizes in the trigonal space group R3m (no. 166) with the lattice parameters a = 298.5(2) and c = 2384.3(4) pm. The niobium atoms form a close packing with a layer sequence which can be described by the Jagodzinski symbol hhc. The nitrogen atoms fill all octahedral voids. Along [001] a sequence of two layers of trigonal NbN6 prisms and one layer of NbN6 octahedra is formed. The nitrogen positions are fully occupied, the niobium positions only partially. Nb0.84N is part of a family of crystal structures between the anti-NiAs and the NaCl type consisting of close-packed metal layers with varying stacking sequences

Polytypism in the BaMn0.85Ti0.15O3−δ System (0.07≤δ≤0.34). Structural, Magnetic, and Electrical Characterization of the 9R-Polymorph

Chemical doping of 15 atom % Mn by Ti in 2H-BaMnO3 leads to two new polytypes, 4H- and 9R-BaMn0.85Ti0.15O3−δ, depending on the oxygen content. The 4H polytype (a = 5.71355(4) and c = 9.41230(8) A, space group P63/mmc) was prepared in an inert atmosphere and forms face sharing dimers linked by corners based on a stacking sequence (hc)2 where h and c refer to hexagonal and cubic BaO3 layers, respectively. Selected area electron diffraction patterns and high resolution electron microscopy reveal the coexistence of two types of crystals; the majority corresponds to an ordered (hc)2-4H polytype whereas a minority fraction shows a disordered microstructure. Such differences may be associated with nonhomogeneous cationic distribution within the crystals. Oxidation in air at 1523 K for 48 days leads to conversion to the 9R polytype (a = 5.68007(1) and c = 20.98208(6) A, space group R3m) with a (hhc)3 stacking sequence; Mn4+ ions are exclusively located on the central B-site (M1) of the face sharing trimers linke...

Crystal growth and defects in Ga3PO7 crystals

AbstractCrystals with a non‐centrosymmetric structure are of great interest owing to their properties such as ferroelectricity, piezoelectricity, dielectric behavior and optical properties. In this letter, Ga3PO7 crystals are grown by the top‐seeded solution growth (TSSG) method from a Li2O‐3MoO3 flux. It crystallizes in a non‐centrosymmetric trigonal crystal system with space group R3m within point group 3m. The growth defects are investigated by means of chemical etching method. The results reveal hot concentrated phosphoric acid to be a good etchant for Ga3PO7. The main defects are cracks, inclusions, dislocations and twin. In the meantime, the effective measures for reducing the defects are proposed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Fabrication and Characterization of LaCoO3 Nanofibers via an Electrospinning Technique

Polyvinyl alcohol(PVA)/[La(NO3)3+Co(CH3COO)2] composite nanofibers were prepared by combination of sol-gelmethod and electrospinning technique, and crystalline LaCoO3 nanofibers were fabricated by calcination of thePVA/[La(NO3)3+Co(CH3COO)2] composite nanofibers at 600ºC for 10h. The samples were characterized by usingthermogravimetric-differential thermal analysis(TG-DTA), X-ray diffraction spectrometry(XRD), scanning electronmicroscopy(SEM) and Fourier transform infrared spectrometry(FTIR). The results show thatPVA/[La(NO3)3+Co(CH3COO)2] composite nanofibers are amorphous in structure, and pure phase LaCoO3 nanofibersare trigonal in structure with space group R3m. The surface of as-prepared composite nanofibers is smooth, and thediameter is about 200nm. The diameter of LaCoO3 nanofibers is smaller than that of the relevant composite fibers. Thesurface of the LaCoO3 nanofibers becomes coarse with the increase of calcination temperatures. The diameter ofLaCoO3 nanofibers is ca. 80nm, and the length is greater than 100?m. The mass of the sample remains constant whenthe temperature is above 500ºC, and the total mass loss percentage is 83%. Possible formation mechanism of LaCoO3nanofibers is preliminarily proposed.