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A porous CuBr film with exclusive NH3 sensing properties is prepared via a simple solution process, which offers the best opportunity for realizing low-cost, wearable devices for indoor air quality monitoring.

Water poisoning has been a long-standing problem in oxide semiconductor gas sensors. Herein, for the first time, we report that pure and Pr-doped Ce4W9O33 provide humidity-independent gas sensing characteristics. Ce4W9O33 and Pr-doped Ce4W9O33 powders with a porous structure have been successfully prepared by ultrasonic spray pyrolysis and subsequent annealing at low temperature (600 °C). Interestingly, these p-type oxide semiconductors exhibited nearly the same gas sensing characteristics at 300 °C regardless of humidity variation, whereas pure WO3 showed a significant decrease of sensor resistance and gas response when the atmosphere is changed from dry to relative humidity 80%. Furthermore, Ce4W9O33-based sensors showed highly selective and sensitive detection of ppm-level trimethylamine (TMA). Moisture-endurant gas sensing characteristics were discussed in relation to surface regeneration through the hydroxyl scavenging reaction assisted by abundant Ln3+ (Ln = Ce, Pr) in (Ce1−xPrx)4W9O33 (x = 0–0.3) and TMA selectivity was explained by the acid–base interaction between the analyte gas and sensing material. Phase-pure ternary or quaternary oxides with a decreased oxidation state of lanthanide components provide a new and general strategy to design humidity-independent gas sensors with new functionality.

Sodium ion batteries (SIBs) have drawn interest as a lithium ion battery (LIB) alternative owing to their low price and low deposits. To commercialize SIBs similar to how LIBs already have been, it is necessary to develop improved anode materials that have high stability and capacity to operate over many and long cycles. This paper reports the development of homogeneous Sb2S3 nanorods (Sb2S3 NRs) on reduced graphene oxide (Sb2S3 NRs @rGO) as anode materials for SIBs. Based on this work, Sb2S3 NRs show a discharge capacity of 564.42 mAh/g at 100 mA/g current density after 100 cycles. In developing a composite with reduced graphene oxide, Sb2S3 NRs@rGO present better cycling performance with a discharge capacity of 769.05 mAh/g at the same condition. This achievement justifies the importance of developing Sb2S3 NRs and Sb2S3 NRs@rGO for SIBs.

Sodium ion batteries (SIBs) have drawn interest as a lithium ion battery (LIB) alternative owing to their low price and low deposits. To commercialize SIBs similar to how LIBs already have been, it is necessary to develop improved anode materials that have high stability and capacity to operate over many and long cycles. This paper reports the development of homogeneous Sb2S3 nanorods (Sb2S3 NRs) on reduced graphene oxide (Sb2S3 NRs @rGO) as anode materials for SIBs. Based on this work, Sb2S3 NRs show a discharge capacity of 564.42 mAh/g at 100 mA/g current density after 100 cycles. In developing a composite with reduced graphene oxide, Sb2S3 NRs@rGO present better cycling performance with a discharge capacity of 769.05 mAh/g at the same condition. This achievement justifies the importance of developing Sb2S3 NRs and Sb2S3 NRs@rGO for SIBs.

Pure and 3-12 at. % Pr-doped In2O3 macroporous spheres were fabricated by ultrasonic spray pyrolysis and their acetone-sensing characteristics under dry and humid conditions were investigated to design humidity-independent gas sensors. The 12 at. % Pr-doped In2O3 sensor exhibited approximately the same acetone responses and sensor resistances at 450 °C regardless of the humidity variation, whereas the pure In2O3 exhibited significant deterioration in gas-sensing characteristics upon the change in the atmosphere, from dry to humid (relative humidity: 80%). Moreover, the 12 at. % Pr-doped In2O3 sensor exhibited a high response to acetone with negligible cross responses to interfering gases (NH3, CO, benzene, toluene, NO2, and H2) under the highly humid atmosphere. The mechanism for the humidity-immune gas-sensing characteristics was investigated by X-ray photoelectron and diffuse reflectance infrared Fourier transform spectroscopies together with the phenomenological gas-sensing results and discussed in relation with Pr3+/Pr4+ redox pairs, regenerative oxygen adsorption, and scavenging of hydroxyl groups.

Nearly monodisperse hollow hierarchical Co3O4 nanocages of four different sizes (∼0.3, 1.0, 2.0, and 4.0 μm) consisting of nanosheets were prepared by controlled precipitation of zeolitic imidazolate framework-67 (ZIF-67) rhombic dodecahedra, followed by solvothermal synthesis of Co3O4 nanocages using ZIF-67 self-sacrificial templates, and subsequent heat treatment for the development of high-performance methylbenzene sensors. The sensor based on hollow hierarchical Co3O4 nanocages with the size of ∼1.0 μm exhibited not only ultrahigh responses (resistance ratios) to 5 ppm p-xylene (78.6) and toluene (43.8) but also a remarkably high selectivity to methylbenzene over the interference of ubiquitous ethanol at 225 °C. The unprecedented and high response and selectivity to methylbenzenes are attributed to the highly gas-accessible hollow hierarchical morphology with thin shells, abundant mesopores, and high surface area per unit volume as well as the high catalytic activity of Co3O4. Moreover, the size, shel...

Reduced graphene oxide (rGO)-In 2 O 3 hybrid materials were prepared by a solvothermal reaction of an In precursor containing rGO sheets, which were coated onto flexible substrates for gas sensors. The rGO-In 2 O 3 flexible sensors showed a high and reversible response (resistance ratio = 22.3) to 500 ppb NO 2 at 150 °C and negligible cross-responses to C 2 H 5 OH, CO, NH 3 , toluene, H 2 , and HCHO. The ultrahigh response and selectivity of rGO-In 2 O 3 hybrid materials to NO 2 were attributed to the chemical affinity of rGO to NO 2 and the extension of the electron depletion layer in n -type In 2 O 3 forming a p - n junction with the p -type rGO.

Pure and 3-12 at. % Pr-doped In

Cr 2 O 3 /ZnCr 2 O 4 nanocomposite powders and phase-pure ZnCr 2 O 4 powders were prepared by the galvanic replacement of Zn in ZnO hollow spheres by Cr and subsequent heat treatment. The Cr 2 O 3 /ZnCr 2 O 4 nanocomposite powders prepared by galvanic replacement consisted of nanocrystalline Cr 2 O 3 and ZnCr 2 O 4 particles, which showed a high response (resistance ratio) of 69.2 to 5 ppm xylene at 275 °C and excellent xylene selectivity. In contrast, both Cr 2 O 3 and ZnO powders showed selectivity to ethanol, and no significant selectivity to a specific gas was found for the ZnCr 2 O 4 powders. The Cr 2 O 3 /ZnCr 2 O 4 composite powders consisting of coarse particles prepared by solid-state reaction showed relatively low response and selectivity to xylene. The high selectivity and response to xylene of the Cr 2 O 3 /ZnCr 2 O 4 nanocomposite powders were attributed to the synergistic promotion of the methylbenzene-sensing reaction by two sensing materials with different catalytic activities and the high chemiresistive variation of the small particles, respectively, both of which result from the intimate and uniform mixing of nanocrystalline Cr 2 O 3 and ZnCr 2 O 4 particles.

The pure and 0.3 wt% Pt-doped SnO2 hollow nanospheres were prepared by the oxidation of pure and Pt-doped Sn nanoscrystals embedded in carbon matrix and their gas sensing characteristics were investigated. The formation of hollow morphology was attributed to the nanoscale Kirkendall effect due to rapid outward diffusion of Sn ions and relatively slow inward diffusion of oxygen. Pure SnO2 hollow nanospheres showed a high response (resistance ratio) of 93.3 when exposed to 5 ppm ethanol. The response to 5 ppm ethanol was significantly increased to 1399.9 with doping 0.3 wt% Pt. In addition, selectivity to ethanol was also enhanced by Pt doping. Ultrasensitive and selective detection of ethanol in pure and Pt-doped SnO2 nanospheres is explained by the effective electron depletion in hollow structures and catalytic promotion of gas sensing reaction.

Nearly monodisperse hollow hierarchical Co

Highly sinterable gadolinia doped ceria (GDC) powders are prepared by carbonate coprecipitation and applied to the GDC interlayer in Ni–YSZ (yttria stabilized zirconia)-supported tubular solid oxide fuel cell in order to prevent the reaction between YSZ electrolyte and LSCF (La0.6Sr0.4Co0.2Fe0.8O3−δ) cathode materials. The formation of highly resistive phase at the YSZ/LSCF interface was effectively blocked by the low-temperature densification of GDC interlayer using carbonate-derived active GDC powders and the suppression of Sr diffusion toward YSZ electrolyte via GDC interlayer by tuning the heat-treatment temperature for cathode fabrication. The power density of the cell with the configuration of Ni–YSZ/YSZ/GDC/LSCF–GDC/LSCF was as high as 906 mW cm−2, which was 2.0 times higher than that (455 mW cm−2) of the cell with the configuration of Ni–YSZ/YSZ/LSM(La0.8Sr0.2MnO3−δ)–YSZ/LSM at 750 °C.

We studied n-type conduction characteristics using p-type BiOCl by oxygen vacancy formation at the exposed (001) surface. This formation of oxygen vacancy at the surface of BiOCl nanosheets, confirmed by ACTEM, XPS and Raman spectra that oxygen vacancy gradually increasing as a function of UV illumination time. The low temperature PL result shows decreasing band edge emission of BiOCl due to high density oxygen vacancies were placed under conduction band edge of BiOCl. The conductivity dependence on oxygen partial pressure reveals n-type characteristic behavior as oxygen vacancies were present.

Metal oxide nanowire network structures are promising chemoresistive materials with a highly sensitive response, good stability and fast response due to their large surface area and gas accessible networked structures. In general, highly crystalline oxides nanowire (NW) networks were prepared by a thermal evaporation process. Those have lots of advantages for the detection of volatile organic compounds (VOCs) and environmental pollution gases. Especially, n-type oxide NWs such as SnO2, ZnO, and In2O3, and Ga2O3 are widely investigated due to their easy synthetization and high gas response. In other to enhance gas response of n-type oxides NWs, doping or loading of noble metals of Pt , Pd, Ag or p-type oxide semiconductor of CuO , Co3O4, NiO, and MnO2. In this study, we investigated for the detection using p-type metal oxide nanoparticles decorated ZnO NWs. Consequently, the surface modification of oxide NWs via various methods provides new approach to accomplish the selective detection of a specific gas, and after further researches, this approach could provide a new strategy in the field of gas sensors.

Punched ZnO nanobelt (NB) network sensors with strong adhesion to Au electrodes were fabricated by the vapor-phase growth of ZnS NB networks and subsequent thermal annealing. The punched ZnO NB networks showed sensitive and selective detection of trimethylamine (TMA), while no significant sensitivity or selectivity to a specific gas was observed in dense ZnO NB networks. This high TMA response can be explained by abundant chemoresistive contacts, effective electron depletion, and high surface area to volume ratio of punched ZnO NB networks.

Gadolinia-doped ceria (GDC, Gd0.1Ce0.9O1.95) powders with high sinterability are prepared by carbonate coprecipitation and applied in the fabrication of Ni–YSZ (yttria-stabilized zirconia)-supported tubular solid oxide fuel cells (SOFCs) with a cell configuration of Ni–YSZ/Ni/Ni–GDC/GDC/LSCF(La0.6Sr0.4Co0.2Fe0.8O3−δ)–GDC/LSCF. A high power density (594 mW cm−2) at 600 °C is achieved using the cell (diameter: 6 mm) prepared by sintering of the electrolyte at 1400 °C. This result is attributed to the dense electrolyte and good adherence between GDC and the electrode. The carbonate-derived GDC powders can be sintered to 97% of the theoretical density even at 1050 °C, which demonstrates that the fabrication temperature of tubular SOFCs can potentially be lowered by using cost-effective Ni–YSZ supports.

NiO and Fe-doped NiO hollow spheres with the shell thickness of ∼12 nm have been prepared by applying uniform coatings of Ni- and Fe-precursors onto Ni spheres, partial oxidation of Ni spheres near their surfaces at 300 °C, the dissolution of core Ni using dilute HCl aqueous solution, and subsequent heat treatment at 500 °C, and their gas sensing characteristics at 300–400 °C were compared. The response to 100 ppm C2H5OH of Fe-doped NiO hollow spheres at 350 °C (Rg/Ra = 172.5; Rg, resistance in gas; Ra, resistance in air) was 31.4 times higher than that of NiO hollow spheres (Rg/Ra = 5.5). The reasons for the significant enhancement of C2H5OH response by doping Fe into NiO hollow spheres were discussed in relation to the incorporation of Fe components into the NiO lattice and their consequent impact on the gas sensing reaction.

Pure ZnO and CuO–ZnO composite hollow spheres were prepared by one-pot, glucose-mediated hydrothermal reaction with subsequent heat treatment. The pure ZnO hollow spheres could selectively detect C 2 H 5 OH at 475 °C. The CuO–ZnO hollow spheres prepared from the solutions with the compositions of [Cu 2+ ]/([Cu 2+ ] + [Zn 2+ ]) = 0.02 and 0.04 showed high responses to 5 ppm H 2 S ( R a / R g = 13.3 and 32.4, R a : resistance in air, R g : resistance in gas) with negligible cross responses to 100 ppm C 2 H 5 OH, C 3 H 8 , CO and H 2 ( R a / R g = 1.4–1.8) at 336 °C. They also showed selective C 2 H 5 OH detection at 475 °C. The dual selective detection of H 2 S and C 2 H 5 OH by the composite particles was due to electrochemical interactions with H 2 S of nano-scale p (CuO)– n (ZnO) junctions within the hollow spheres.

A SnO 2 nanowire-based transparent flexible device was fabricated via a simple transfer method and its optoelectronic properties were investigated. SnO 2 nanowires grown on an Au-patterned Si substrate by thermal evaporation were simply transferred to a polyester film with an adhesive followed by screen printing of Ag electrodes. The fabricated flexible device exhibited good ohmic behaviors in the dark state as well as a high photoconductivity and a good on/off ratio of 10 4 under the UV irradiation with a wavelength of 254 nm.

Highly sensitive detection of volatile organic compounds, such as C2H5OH and HCHO, has been achieved by decorating p-type NiO nanoparticles on n-type ZnO nanowire networks, whereas the incorporation of Ni into the lattice of the ZnO nanowires deteriorated the gas sensing characteristics.

Manganese gallium oxide (MnGa2O4) one-dimensional nanostructures were synthesized by the thermal evaporation of MnCl2/Ga/Zn. The single-crystalline spinel-structured MnGa2O4 nanowires are preferentially grown in the [111] direction. In contrast, the Zn (10%)-doped MnGa2O4 nanostructures adopt zigzag structures. Some of them are nanosprings that consist of four equivalent [011] growth directions with the axial [001] direction. The nanobelts often have two zigzagged [011] directions along the long axis parallel to the [112] direction. We discuss the growth model of these unique zigzagged nanostructures. The MnGa2O4 nanostructures exhibit the emission at 2.5 eV (7 K), which possibly originated from the d−d transition of the tetrahedrally coordinated Mn2+ ions, and the decreased intensity with the Zn doping. The magnetization measurements indicate that these MnGa2O4 nanostructures exhibit virtually paramagnetic behaviors.

High-purity N-doped double-walled carbon nanotubes (DWNTs) were synthesized by chemical vapor deposition, and investigated by synchrotron X-ray photoelectron spectroscopy (XPS). As the photon energy increases, the N content increases up to 3 at.%, indicating that the inner wall contains the higher N content than the outer wall. The graphite-like and pyridine-like N structures exist as about 1:1 ratio. The self-consistent charge-density-functional-based tight-binding calculation shows that the N-doping of the inner wall yields the more stable DWNT than that of the outer wall, which supports the XPS result.

Two longitudinal superlattice structures of In2O3(ZnO)4 and In2O3(ZnO)5 nanowires were exclusively produced by thermal evaporation method. The diameter is periodically modulated in the range of 50-90 nm. They consist of one In-O layer and five (or six) layered Zn-O slabs stacked alternately perpendicular to the long axis, with a modulation period of 1.65 (or 1.9) nm. These superlattice nanowires were doped with 6-8 % Sn. X-ray diffraction pattern reveals the structural defects of wurtzite ZnO crystals due to the In/Sn incorporation. High-resolution X-ray photoelectron spectrum suggests that In/Sn withdraw the electrons from Zn, and enhance the number of dangling-bond O 2p states, resulting in the reduction of band gap. Photoluminescence exhibit the peak shift of near band edge emission to the lower energy as the In/Sn content increases.

ZnO nanowires doped with a high concentration Ga, In, and Sn were synthesized via thermal evaporation. The doping content defined as X/(Zn + X) atomic ratio, where X is the doped element, is about 15% for all nanowires. The nanowires consist of single-crystalline wurtzite ZnO crystal, and the average diameter is 80 nm. The growth direction of vertically aligned Ga-doped nanowires is [001], while that of randomly tilted In- and Sn-doped nanowires is [010]. A correlation between the growth direction and the vertical alignment has been suggested. The broaden X-ray diffraction peaks indicate the lattice distortion caused by the doping, and the broadening is most significant in the case of Sn doping. The absorption and photoluminescence of Sn-doped ZnO nanowires shift to the lower energy region than those of In- and Ga-doped nanowires, probably due to the larger charge density of Sn.

We report synthesis of wurtzite structured gallium nitride nanowires via a chemical vapor deposition of gallium, gallium nitride, and boron oxide mixture under ammonia atmosphere. All nanowires exhibit the same [0 0 1] growth direction. The majority of nanowires are extremely thin and long; the diameter is 5–10 nm and the length is 40–50 μm. The larger diameter nanowires exhibit a zigzag configuration with amorphous boron outerlayers. X-ray diffraction and Raman spectroscopy reveal no significant strains inside the nanowires.

Single-crystalline Mn(3)O(4) nanowires were prepared using the vapor-phase transformation of ZnO nanobelts. Mn(3)O(4)-decorated ZnO nanobelts and ZnO-ZnMn(2)O(4) core-shell nanocables (NCs) were also obtained as reaction intermediates. Heteroepitaxial growth of tetragonal spinel Mn(3)O(4) (or ZnMn(2)O(4)) on wurtzite ZnO is a possible reason for the growth of single-crystalline Mn(3)O(4) nanowires. Growth interfaces are possibly formed between the wurtzite (101[overline]0)/(21[overline]1[overline]0) and spinel (1[overline]01)/(4[overline]11) planes. Various one-dimensional homonanostructures and heteronanostructures consisting of n-ZnO, p-Mn(3)O(4), and p-ZnMn(2)O(4) can be used to design high-performance gas sensors.

Single-crystalline Mn2SnO4 nanowires were first synthesized by chemical vapor deposition; they consist of inverse spinel structure grown with the [111] direction; the nanowires have a ferrimagnetic phase below 46 K (T(C)) with large hysteresis; this ferrimagnetic transition is probably due to the presence of Mn3+ ions at octahedral sites.

Cd1-xMnxS (x = 0.1-0.3) nanowires were synthesized by using the chemical vapor deposition method. They all consist of a single-crystalline wurtzite CdS structure with a [010] or [011] growth direction. The X-ray diffraction pattern reveals the contraction of the lattice constants due to the incorporation of Mn. The Mn2+ emission at approximately 2.15 eV, originating from the d-d (4T1 --> 6A1) transition, appears below 50-80 K. Its decay time is in the range of 0.55-1 ms, showing a decrease with increasing Mn content. The Mn doping reduces significantly the decay time of band-edge emission from 590 ps to 20-30 ps. Upon applying magnetic field (up to 7 T), the Mn2+ emission is suppressed and donor-acceptor pair emission becomes dominant, suggesting the energy transfer from the band electrons to the Mn2+ ions.

We report Mn-doped GaN nanowires exhibiting ferromagnetism even at room temperature. The growth of single-crystalline wurtzite structured GaN nanowires doped homogeneously with about 5 atomic % Mn was achieved by chemical vapor deposition using the reaction of Ga/GaN/MnCl2 with NH3. The ferromagnetic hysteresis at 5 and 300 K and the temperature-dependent magnetization curves suggest the Curie temperature around 300 K. Negative magnetoresistance of individual nanowires was observed at the temperatures below 100 K.

A high-density array of vertically aligned ZnGa(2)O(4) nanowires has been synthesized on Si substrates via CVD of ZnO-Ga at 1000 degrees C consisting of a single-crystalline cubic spinel structure grown in a [111] direction and exhibiting strong photoluminescence and cathodoluminescence in the blue wavelength region.

Highly selective and sensitive detection of trimethylamine (TMA) was achieved by the decoration of discrete p-type Cr(2)O(3) nanoparticles on n-type ZnO nanowire (NW) networks. Semielliptical Cr(2)O(3) nanoparticles with lateral widths of 3-8 nm were deposited on ZnO NWs by the thermal evaporation of CrCl(2) at 630 °C, while a continuous Cr(2)O(3) shell layer with a thickness of 30-40 nm was uniformly coated on ZnO NWs at 670 °C. The response (R(a)/R(g): R(a), resistance in air; R(g), resistance in gas) to 5 ppm TMA of Cr(2)O(3)-decorated ZnO NWs was 17.8 at 400 °C, which was 2.4 times higher than that to 5 ppm C(2)H(5)OH and 4.3-8.4 times higher than those to 5 ppm p-xylene, NH(3), benzene, C(3)H(8), toluene, CO, and H(2). In contrast, both pristine ZnO and ZnO (core)-Cr(2)O(3) (shell) nanocables (NCs) showed comparable responses to the different gases. The highly selective and sensitive detection of TMA that was achieved by the deposition of semielliptical Cr(2)O(3) nanoparticles on ZnO NW networks was explained by the catalytic effect of Cr(2)O(3) and the extension of the electron depletion layer via the formation of p-n junctions.

Highly crystalline CoO and Co3O4 nanowires were prepared by vapor-phase conversion of ZnO nanobelts. The ZnO nanobelts were successfully transformed into highly crystalline CoO nanowires by thermal evaporation of CoCl2 at 700 °C in Ar, which were subsequently converted to Co3O4 nanowires by oxidative annealing at 600 °C. The reactions at 500 and 550 °C in 0.5% O2 led to the formation of well-defined oxide p–n junction nanostructures such as Co3O4-decorated ZnO nanobelts and ZnO–ZnCo2O4 core–shell nanocables, respectively, as the reaction intermediates. The evolutions of phase and residual Zn component during the conversion were investigated in relation to the reaction temperature and oxygen partial pressure.

One-dimensional CoO–ZnO:Co hetero-nanostructures were prepared by vapor phase growth. Ferromagnetism was observed at room temperature, which is ascribed to Co diffusion into ZnO nanorods grown over CoO nanowires. Strong enhancement in green emission intensity was also observed.

The selective detection of two different gases, NO(2) and C(2)H(5)OH, has been achieved using a p-type Co(3)O(4)-decorated n-type ZnO nanowire (NW) network sensor. The gas selectivity was explained by the catalytic effect of nanocrystalline Co(3)O(4) and the extension of the electron depletion layer via the formation of p-n junctions.

Magnetite (Fe3O4) hollow spheres were prepared by solvothermal reaction of ethanol solution containing Fe-acetate and L-lysine, and were subsequently transformed into hematite (Fe2O3) hollow spheres with nanoscale (20–30 nm) thin shells by heat treatment at 500 °C for 2 h. Both the as-prepared and heat-treated hollow spheres contained another small sphere within each shell, which was attributed to the following solvothermal self-assembly reactions: (1) the nucleation of Fe3O4 spheres, (2) lysine capping on the nuclei, (3) the growth of lysine-capped particles by cross-linking between lysine molecules, and (4) the formation of Fe shell layers by the interaction between Fe ions and outer lysine molecules. In the assembly reaction, L-lysine with amino and carboxyl radicals played the key role. The heat-treated Fe2O3 hollow spheres showed significantly enhanced C2H5OH sensing characteristics and promising Li-ion intercalation behaviors.

Rh-loaded In2O3 hollow spheres with diameters of ∼2 μm were prepared by a one-pot hydrothermal reaction of aqueous solution containing indium nitrate, rhodium chloride, and glucose and subsequent heat treatment at 500 °C for 2 h. The response to 100 ppm C2H5OH (Ra/Rg, Ra: resistance in air, Rg: resistance in gas) of 1.67 at% Rh-loaded In2O3 hollow spheres was 4748, which was ∼180 times higher than that of pure In2O3 hollow spheres. Rh loading decreased the temperature for maximum gas response from 475 °C to 371 °C, which also enhanced the selectivity to C2H5OH 15.1–24.7 times and recovery speed. The ultrahigh sensitivity and selectivity to C2H5OH, the lower sensing temperature, and the reduced recovery time were attributed to electronic interactions between Rh and In2O3 and the promotion of catalytic dissociation of C2H5OH into reactive gases.

Mixture of single-crystalline MnO and Mn3O4 nanowires was synthesized by thermal evaporation of MnCl2 powders. The diameter is 50–100nm, the length is about 20μm, and the growth direction is uniformly [100] for both cubic MnO and tetragonal Mn3O4 nanowires. The temperature-dependent magnetization and magnetic hysteresis curves suggest the Curie temperature of 12 and 43K for the MnO and Mn3O4 nanowires, respectively.

High-density Zn0.85In0.15O and Zn0.75In0.25O nanowires were synthesized by thermal evaporation method. They consist of single-crystalline wurtzite ZnO structure with uniform [010] growth direction. X-ray diffraction (XRD) reveals the structural defects caused by the In incorporation. X-ray photoelectron spectrum (XPS) analysis suggests that In withdraw the electrons from Zn and increase the dangling-bond O2p states. The lower energy shift and green-band enhancement of photoluminescence are well correlated with the results of XRD and XPS.