•c-Axis oriented (Bi2Ba3O4−δ)b1/b2CoO2 films are prepared by a solution method.•Annealing temperature effects on microstructures and TE properties are reported.•The optimized annealing temperature is as low as 600 °C.•Transport mechanisms for (Bi2Ba3O4−δ)b1/b2CoO2 films are deeply investigated.(Bi2Ba3O4−δ)b1/b2CoO2 (BBC) thin films are prepared on LaAlO3 (001) single crystal substrates by chemical solution deposition. The annealing temperature effects on the thin film microstructures as well as transport properties are investigated. The results of X-ray diffraction, energy dispersive spectrometry and transmission electron microscopy confirm the formation of stoichiometric BBC thin films with c-axis orientation. Annealing temperature plays a very important role in determination of resistivity and Seebeck coefficient due to the variations of grain size, carrier concentration and mobility. The resistivity behaviors for the different temperature-annealed thin films obey different electrical transport mechanisms at low, medium and high measured temperature ranges. The optimized BBC thin film is annealed at 600 °C, showing a metal-insulator transition at about 100 K and the resistivity and Seebeck coefficient at 300 K is of 8.7 mΩ cm, 74.4 μV K−1, respectively. The results will provide an effective route to fabricate BBC thin films as well as a guidance for investigation about its transport properties.

•Bi6Fe2Ti3O18/LaNiO3/Si thin films are successfully prepared by an all-solution route.•Annealing temperature effects on microstructures and properties are investigated.•Room-temperature multiferroic properties are observed.An all-solution approach is successfully used to deposit Bi6Fe2Ti3O18 (BFTO18) thin films onto solution-derived LaNiO3/Si substrates. The effects of annealing temperature on the dielectric, leakage, ferroelectric and magnetic properties are investigated. The mechanisms about the annealing dependence of dielectric, leakage and ferroelectric properties are discussed in detail. Room-temperature weak ferromagnetism is observed for all the derived thin films. The results will provide an effective route to prepare BFTO18 multiferroic thin films with large area by low-cost solution method.Room-temperature multiferroic properties are observed.

Recent progress in transparent conducting components stimulates the extensive exploration of p-type transparent conducting oxide (TCO) materials. Here, we report the synthesis of a class of p-type delafossite Ag-based TCO thin films, AgCrO2 (ACO), using a facile chemical solution route in an open condition. Firstly, the evolution of microstructure, morphology, and optical properties with respect to annealing temperature is reported. The stoichiometric ACO thin films show self-assembled c-axis orientation. The 500 °C-annealed ACO thin film presents a relatively high quality, dense surface and good optical transmittance amongst all the derived thin films. Then, to improve the conductivity, Mg doping effects are investigated. Upon Mg doping, p-type conductivity is obtained for thin films of AgCr1−xMgxO2 (0.04 ≤ x ≤ 0.20). The conductivity initially increases from 3.1 × 10−3 to 67.7 × 10−3 S cm−1 with x increasing from 0.04 to 0.12 and then slightly decreases with further increasing Mg concentration. The Hall results display that the hole concentration gradually increases with increasing Mg dopant concentration, and the carrier mobility first increases with x increasing from 0.04 to 0.12, while decreases with x further increasing from 0.12 to 0.20. A high magnitude of optical transmittance near 60% in the visible region and wide optical bandgaps (3.41–3.66 eV) of the AgCr1−xMgxO2 thin films are observed. The facial fabrication of ACO thin films in an open condition will provide a start for the synthesis of Ag-based delafossite thin films.

•Bi6Fe2Ti3O18 thin films with thickness below 100 nm are first prepared by sol-gel.•Room temperature Pr is higher than 10 μC/cm2 at 5 V driving voltage.•Weak ferromagnetism is observed at 5 K.Bi6Fe2Ti3O18 thin film on Pt/Ti/SiO2/Si substrate with a thickness of 85 nm is successfully prepared by a monoethanolamine-modified sol-gel processing. The prepared thin film is polycrystalline and shows dense morphology. The room temperature remnant polarization is higher than 10 μC cm−2 at 5 V driving voltage both from polarization-voltage hysteresis loop and positive-up negative-down measurements. The polarization after 107 switching cycles and a retention time of 104 s shows no obvious degradation, suggesting good fatigue-resistant characteristics. Weak ferromagnetism is observed at 5 K with a saturated magnetic moment of 11.7 emu/cm3. The results will provide an effective route to optimize Bi6Fe2Ti3O18 thin films with thickness below 100 nm by low-voltage driving.

•CoFe films were prepared by chemical solution processing.•The films density is improved by high magnetic field annealing.•Saturation magnetization of CoFe films are enhanced by magnetic field annealing.Co-Fe alloy thin films with high magnetization are desirable in numerous applications. Co-Fe thin films prepared by solution methods with refined microstructures have not been achieved up to now. Here, high magnetic field annealing (HMFA) is introduced for the preparation of Co70Fe30 alloy thin films. The effects of HMFA on their microstructures and room temperature magnetic properties are investigated. The thickness of the derived Co70Fe30 thin films is dramatically decreased from a value of 590 nm without HMFA to 320 nm with 7 T magnetic field annealing, and the refinement of microstructures is also observed with HMFA. The derived Co70Fe30 film annealed under 7 T magnetic field exhibits a saturation magnetization of ∼2.43 T, close to the theoretical value of 2.45 T. Overall, HMFA provides a feasible way to fabricate larger-area and denser Co-Fe thin films with excellent magnetic properties.

Multiferroic BiFeO3 (BFO) thin films with a thickness larger than 400 nm are grown on solution-derived LaNiO3 coated Si substrates via chemical solution deposition. The prepared BFO/LaNiO3/Si thin films are strongly (00l)-oriented with a distorted rhombohedral structure of R3c symmetry. The effects of the annealing temperature within the temperature range of 500–650 °C on the microstructures and properties are investigated. With an annealing temperature increasing to 600 °C, the (00l) orientation is enhanced and the grain size is increased, whereas a higher annealing temperature will lead to the deterioration of the orientation and microstructures. The annealing temperature dependent dielectric, leakage and ferroelectric properties are investigated, showing excellent properties for the low temperature annealed BFO thin films. The mechanisms about annealing temperature effects are discussed. The results will provide an effective route to realize the integration of large-area BFO thin films on Si wafers by an all-solution approach with low cost.

As the most-studied multiferroic material, (111)-oriented BiFeO3 (BFO) thin films are desirable due to the highest polarization in the (111) plane. The difficulty of achieving large-area (111)-oriented BFO films on silicon wafers towards implementation with silicon technology has hindered the development of BFO films. Herein, we report the annealing temperature effects on chemical solution deposition (CSD) derived BFO films on Pt(111)/Ti/SiO2/Si substrates without any buffer layer. The derived BFO films shows a strong (111) orientation with a distorted rhombohedral structure and R3c space group. The annealing temperature effects on the microstructures as well as the properties were investigated. A dense and crack-free surface was obtained in the low-temperature annealed films. Relatively high room-temperature remnant polarization 2Pr (120–140 μC cm−2) could be obtained with low leakage (∼10−5 A cm−2 at 200 kV cm−1). Scanning electron microscopy and transmission electron microscopy showed that this is an available route for fabricating large-area (111)-oriented BFO films on silicon-based wafers with high 2Pr using low-cost solution processing.

Preparation of antiperovskite thin films is challenging work due to their complex phase diagram and easy decomposition during processing, which hinder the fundamental studies and applications. Herein, we report the preparation of antiperovskite CuNCo3 (CNC) thin films on several different single crystal substrates by chemical solution deposition. The results show that the derived CNC thin films are c-axis oriented regardless of the substrate orientation, suggesting the self-assembled c-axis orientation. The microstructures as well as the physical properties are investigated, showing that the CNC thin films are metallic and can be considered as a new type of soft-magnet with a ferromagnetic Curie temperature higher than 650 K. The results will provide an effective route for fabricating antiperovskite cobalt-based thin films as well as provide a prototype for the investigation of the growth mechanisms of complex metal nitride thin films by solution methods.

For practical applications of ferroelectric memory, a large remnant polarization in nontoxic Pb-free ferroelectric materials is required. We prepared Bi6Fe2Ti3O18 thin films on Pt/Ti/SiO2/Si (100) substrates by chemical solution deposition using different annealing processes and found that a well-defined ferroelectric hysteresis loop with a rather large remnant polarization (Pr ≈ 21.5 μC cm−2) occurs in Bi6Fe2Ti3O18 thin films prepared by rapid thermal annealing in air. This value of remnant polarization is superior to those of other ferroelectric Aurivillius compounds such as Bi2WO6, Bi3TiNbO9, Bi4Ti3O12, Bi5FeTi3O15, and Bi6Fe2Ti3O18 thin films prepared by chemical solution deposition and pulsed laser deposition. The results of X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and ferroelectric P–E hysteresis loops revealed that the grain size, surface morphologies, oxygen vacancies and lattice distortion play very important roles in the determination of the remnant polarization. The present study provides an effective route to prepare layered Aurivillius thin films with a large remnant polarization by chemical solution deposition.

Transparent conducting p-type Bi2Sr2Co2Oy thin films have been first grown on SrTiO3 substrates by a chemical solution deposition, showing c-axis self-orientation. The figure of merit can reach as high as 800 MΩ−1, which is the highest value for p-type transparent conducting thin films by solution methods.

Epitaxial antiperovskite superconducting CuNNi3 thin films have been grown by chemical solution deposition. The film is a type II superconductor and shows a Tc of 3.2 K with a transition of 0.13 K. The Hc2(0) and ξ0 are estimated to be 8.1 kOe and 201 Å, respectively.

Monodisperse porous Ni0.5Zn0.5Fe2O4 nanospheres have been successfully synthesized by the solvothermal method. The diameter of the nanospheres can be tuned by controlling the reactant concentration. Lower reactant concentration is favoured for the synthesis of mesoporous Ni0.5Zn0.5Fe2O4 nanospheres with higher surface area. The electrochemical results show that mesoporous Ni0.5Zn0.5Fe2O4 nanospheres exhibit high reversible specific capacity (1110 mAh g−1) for Li storage and high capacity retention, with 700 mAh g−1 retained up to 50 cycles. The excellent electrochemical properties could be attributed to the large surface area and mesoporous structure. The results suggest that Ni0.5Zn0.5Fe2O4 could be a promising high capacity anode material for lithium ion batteries.

In this work, BiFeO3 (BFO) thin films were prepared on metallic Ni (200) tapes with and without a La0.5Sr0.5TiO3 (LSTO) buffer layer at different temperatures by chemical solution deposition. The effects of the annealing temperature as well as the LSTO buffer layer on the dielectric, leakage and ferroelectric properties have been studied in detail. The crystallite size, dielectric constant and leakage current density increase, while the coercive field decreases with increasing annealing temperature. The BFO thin films deposited directly on the Ni tapes are prone to wrinkling, while the wrinkles are smoothed by introducing a thin LSTO buffer layer. Decreased compressive microstrain as well as improved ferroelectric and leakage properties are observed in the BFO thin films deposited on the LSTO buffered Ni tapes. The results will provide an instructive route to optimize BiFeO3-based thin films on metallic tapes by chemical solution deposition methods.

CrN thin films are first prepared by a facile chemical solution deposition method. The results show that the derived CrN thin films are nanocrystalline with the grain size of 30–60 nm. X-ray photoelectron spectroscopy measurement shows the stoichiometry of the derived thin film. The temperature dependent resistivity within the range of 2–300 K shows a semiconductor-like behavior with dρ/dT < 0 and a discontinuity in resistivity at 253 K is observed due to the antiferromagnetic transition. At 10 K the magnetoresistance is as low as −0.06% under 45 kOe. The first growth of CrN thin films by the facile chemical solution deposition will provide an alternative route to prepare CrN thin films, especially for large-area CrN thin films with low-cost.

Ca3Co4O9 thin films have been first prepared on polycrystalline Al2O3 substrates using chemical solution deposition method by multiple annealing processing. It is observed that the derived thin films are c-axis oriented although the substrates are polycrystalline Al2O3 substrates, suggesting the self-assembled c-axis orientation. The annealing temperature effects on the properties are investigated and discussed. The best performances are attributed to the 850 °C-annealed sample, whose resistivity, Seebeck coefficient and power factor at 300 K are 7.4 mΩ cm, 117 μV/K and 0.18 mW/m K−2 respectively, which is even better than those of the thin films deposited on single crystal substrates. The results will provide an effective route to optimize the properties of Ca3Co4O9 thin films using chemical solution deposition by multiple annealing processing even the substrates are polycrystalline.

Polycrystalline La2NiMnO6 thin films are prepared on Pt/Ti/SiO2/Si substrates by the sol–gel method. Through controlling the processing parameters, the cation ordering can be tuned. The disordered and ordered thin films exhibit distinct differences for crystal structures as well as properties. The crystal structure at room temperature characterized by X-ray diffraction and Raman spectra is suggested to be monoclinic (P21/n) and orthorhombic (Pbnm) for the ordered and disordered thin films, respectively. The ferromagnetic–paramagnetic transition is 263 K and 60 K for the ordered and disordered samples respectively, whereas the saturation magnetic moment at 5 K is 4.9 μB fu−1 (fu = formula unit) and 0.9 μB fu−1. The dielectric constant as well as magnetodielectric effect is higher for the ordered La2NiMnO6 thin films. The magnetodielectric effect for the ordered thin film is dominantly contributed to the intrinsic coupling of electric dipole ordering and fluctuations and magnetic ordering and fluctuations, while it is mainly contributed to Maxwell–Wagner (M–W) effects for the disordered thin film. The successful achievements of ordered and disordered polycrystalline La2NiMnO6 thin films will provide an effective route to fabricate double-perovskite polycrystalline thin films by the sol–gel method.

Bi2Sr3Co2Oy thin films are prepared on SrTiO3 (100), (110) and (111) single crystal substrates using the sol–gel method. All the thin films are c-axis oriented regardless of the orientation of the substrate suggesting self-assembled c-axis orientation, and X-ray photoelectron spectroscopy results give evidence of coexistence of Co3+ and Co2+ ions in the derived films. Transmission electronic microscopy observations reveal that all samples are c-axis oriented with no obvious differences for different samples, and the c-axis lattice constant is determined as ∼15 Å suggesting the misfit structure. A phenomenological thermodynamic phase diagram for self-assembled c-axis orientation is established for misfit cobaltate-based films using chemical solution deposition. All samples behave like semiconductors due to the coexistence of Co3+/Co2+ ions, and the resistivity at 350 K is ∼47, 39 and 17 mΩ cm for the thin films on SrTiO3 (100), (110) and (111), respectively, whereas the Seebeck coefficient at 300 K is 97, 89 and 77 μV K−1. The successful attainment of Bi2Sr3Co2Oy thin films with self-assembled c-axis orientation will provide an effective prototype for investigation of growth mechanisms in complex oxide thin films with a misfit structure.

In this article, ZnO:Cd films were successfully deposited on glass substrates by a sol–gel technique. The influence of doping concentration and annealing temperature effects was carefully investigated. All films exhibited c-axis preferential orientation and optical transparency with visible transmittance >80%. The minimum room temperature resistivity of 0.0341 Ω cm was obtained with 10 at.% Cd doping under 600 °C annealing temperature. The optical band gap of ZnO:Cd film was reduced as Cd doping concentration increased, while the band gap increased with the increase of annealing temperature.Research highlights► Sol–gel derived ZnO:Cd thin film exhibits c-axis preferential orientation even if Cd doping concentration reaches up to 30%. Meanwhile, the room temperature resistivity does not decrease monotonously with the increase of Cd doping concentration.

In situ magnetic annealing effects on c-axis-preferred multiferroic BiFeO3/CoFe2O4 bilayered by chemical solution deposition route are investigated. It is observed that magnetic annealing can enhance the crystallization quality, texture and densification as well as dielectric properties. In addition, the magnetolosses decrease with increasing the magnetic fields. Moreover, both increase of the polarization and decrease of the leakage current due to magnetic annealing are beneficial for potential applications of BiFeO3 films.Research highlights► Enhanced c-axis oriented BFO/CFO bilayered thin films were prepared via magnetic annealing. ► It is observed that, the polarization and leakage current of the bilayered thin films increases and decreases respective with the magnetic annealing, which is very useful for applications.

Mg-doped CuAlO2 thin films are prepared by the chemical solution method. The XRD results show that the solid solubility of Mg species on Al sites in CuAlO2 lattice is lower than 2 at.%. When less than 2 at.% of Mg is added to the CuAlO2 film, the surface roughness of the films was reduced with Mg substitution. Moreover, the c-axis orientation of the films improves because the in-plane fusion between CuAlO2 crystallites is hindered. Optical and electrical measurements show that substituting Al3+ in the films with Mg2+ increases both their transmittance in the visible region and their optical band gaps. As well, their electrical conductivity is enhanced. At 300 K, the conductivity of the 1 at.% Mg-doped sample is up to 5.2 × 10−3 S/cm. Thus, Mg-doped CuAlO2 films may have potential applications as transparent conductive oxides.Research highlights▶ Mg-doped CuAlO2 thin films were prepared by chemical solution deposition (CSD) process. As a simple preparation route, CSD has its unique advantages, such as homogeneity at the molecular level, easy introduction of dopants, high deposition rate, non-vacuum deposition. ▶ CuAl1−xMgxO2 thin films produced by CSD method have high optical transparency, comparable even to the film prepared by other physical methods despite their slightly lower electrical conductivity. ▶ Through comparing with the results reported by other researchers, some novel phenomena were observed in our experiments, such as the decreased solubility of Mg species, the enhancement of c-axis orientation, the decrease of surface roughness, the increase of optical band gaps and the variation of transmittance in the ultraviolet region.

Single-phase delafossite CuAlO2 thin films are deposited successfully on Al2O3 (001) and YSZ (100) substrates using the chemical solution method. X-ray diffraction data present that the CuAlO2 film on the Al2O3 (001) substrate is epitaxial, whereas that on YSZ (100) is c-axis oriented; the same is also demonstrated by the HRTEM images and SAED patterns. Optical transmittance spectra exhibit that both films have high transparency in the visible region. However, in this region, the optical transmittance of the CuAlO2 thin film deposited on (001) Al2O3 is inferior to that deposited on (100) YSZ. This optical anomaly can be attributed to surface scattering. Electrical transport measurements show that the resistivity of the film on (001) Al2O3 is one order lower than that on (100) YSZ, suggesting that in-plane orientation is significant in improving hole mobility.

Cr-doped CuAlO2 thin films were deposited on sapphire substrates by chemical solution deposition. The polycrystalline phase structure of CuAl1 − xCrxO2 (x = 0–0.015) thin films was confirmed using an X-ray diffractometer in grazing incidence mode. All specimens are phase-pure. Optical–electrical property measurements show that with increasing Cr amount, electrical resistivity decreases from x = 0 to 0.01, followed by an increase of x = 0.015. This implies that two mechanisms affecting conductivity coexist and compete with each other. The predominance of the mechanisms changes with the increase in the Cr content. The detailed investigation on the transmittance in the ultraviolet region suggests that Cr doping can modify the structure of the top of valence band (VB) because Cr 3d states contribute to VB. Finally, 1% Cr doping can realize the best optimization of optical–electrical property with respect to transparent conducting oxide thin films.

Epitaxial-stabilized (110) NdNiO3−δ films were first realized successfully by chemical solution deposition under ambient oxygen annealing. Cross-section transmission electronic microscopy observation demonstrates the interface is sharp and coherent due to epitaxial stabilization. The resistance change across the metal−insulator transition, the transition sharpness, as well as the metallic state at 300 K are about 500, 0.14 − ln Ω/K ln K, and 0.03 1/K2, respectively, which are comparable to the values for the films formed by vacuum-based methods, indicating the high-quality of the derived films. The successful achievement of (110) NdNiO3−δ films with a sharp metal−insulator transition will provides an alternative route for preparation of high-quality perovskite nickelate films using ambient oxygen annealing.

ZnO:Al thin films were prepared on n-type (1 0 0)-oriented Si and glass slide substrates by chemical solution deposition method. The effects of Al content, the annealing temperature in air, the annealing temperature in reducing atmosphere and the solution concentration on the structural, morphological, electrical and optical characteristics have been investigated systematically. The results show that the processing parameters play an important role in the microstructures as well as the properties. The lowest resistivity value (0.091 Ω cm) was observed by optimization of the processing parameters.

Sol-gel as a versatile method for the preparation of oxide ceramics was used to prepare the delafossite-structured p-type CuAlO2 ceramics. The results showed that mechanical milling is necessary to prepare pure CuAlO2 ceramics using short annealing periods, and the particle size of CuAlO2 ceramics prepared from the powders with mechanical milling procedures was smaller than that derived from powders without mechanical milling. The prepared CuAlO2 ceramics behaved like semiconductors and the thermally activated energy near room temperature was about 0.175 eV.

Sr2FeMoO6 film was successfully deposited on LaAlO3 (00l) substrate via chemical solution deposition using low cost precursor materials of Sr nitrate, Fe nitrate, and ammonia-complexed molybdic acid. The X-ray diffraction, field-emission scan electron microscopy and atomic force microscopy results showed that the Sr2FeMoO6 film was highly (00l)-oriented and relatively smooth and dense with few undesired SrMoO4 phase. The transport and magnetic measurements showed that the Sr2FeMoO6 film had a Curie temperature at 368 K and behaved like semiconductors, which could be attributed to the large Fe/Mo disorders. Further works about improving the Fe/Mo order as well as the low-field magnetoresistance are being carried out and will be reported elsewhere.

SrTiO3 (STO) thin films on BaxSr1−xTiO3 (x = 0.3, 0.5) seed layers buffered Ni (2 0 0) substrates were fabricated using spinning coating technique. It was found that seed layer could affect remarkably the orientation and microstructure of subsequent STO precursor layer. The variations of orientations and microstructures of STO films were discussed.

•δ-MoN thin films are deposited on Si substrates by chemical solution deposition.•Tc is higher than 10 K even the annealing atmosphere is ambient NH3.•Physical properties are investigated in detailed.Molybdenum nitrides Mo-N are considered as the hardest superconducting metal nitrides, which are usually prepared under high pressure and high temperature to obtain high superconducting transition temperature Tc. Here, polycrystalline δ-MoN thin films with self-assembled c-axis orientation are directly deposited onto Si substrates by chemical solution deposition under ambient NH3 annealing atmosphere without high pressure processing. The prepared δ-MoN/Si thin films show Tc higher than 12 K. The normal state resistivity obeys electron-phonon scattering mechanism and can be well fitted by Bloch-Grüneisen expression. The results will provide an effective route to prepare large-area δ-MoN/Si thin films with high Tc as well as a guidance to investigate the fundamental properties of polycrystalline δ-MoN thin films.

•The CFO films show the largest room-temperature Hc amongst the sol-gel derived ones.•(BH)max and Mr/Ms are also the largest amongst the CFO films derived in this way.•Grain size and residual strain are the key to the improved films magnetic properties.CoFe2O4 (CFO) thin films with high coercivity HC are desirable in applications. The difficulty in achieving large-area CFO thin films with high coercivity by sol-gel has hindered the development of CFO thin films. Herein, polycrystalline CFO thin films with the room temperature out-of-plane and in-plane coercivity HC respectively reached ~5.9 and 3.6 kOe has been achieved on the silicon substrate by sol-gel. The room-temperature maximum magnetic energy product (BH)max and remanence ratio Mr/Ms are of 1.66 MG Oe and 0.58 respectively, which are also the largest values amongst the CFO thin films prepared by solution methods. At the same time, annealing temperature and thickness effects on the HC, (BH)max and Mr/Ms of the derived CFO thin films have been investigated. It is observed that grain size and residual tensile strain in the derived films play an important role in the variations of HC and Mr/Ms. These results will provide an effective route for fabricating larger-area high-coercivity CFO thin films with low-cost by sol-gel on silicon wafers.

Recent progress in transparent conducting components stimulates the extensive exploration of p-type transparent conducting oxide (TCO) materials. Here, we report the synthesis of a class of p-type delafossite Ag-based TCO thin films, AgCrO2 (ACO), using a facile chemical solution route in an open condition. Firstly, the evolution of microstructure, morphology, and optical properties with respect to annealing temperature is reported. The stoichiometric ACO thin films show self-assembled c-axis orientation. The 500 °C-annealed ACO thin film presents a relatively high quality, dense surface and good optical transmittance amongst all the derived thin films. Then, to improve the conductivity, Mg doping effects are investigated. Upon Mg doping, p-type conductivity is obtained for thin films of AgCr1−xMgxO2 (0.04 ≤ x ≤ 0.20). The conductivity initially increases from 3.1 × 10−3 to 67.7 × 10−3 S cm−1 with x increasing from 0.04 to 0.12 and then slightly decreases with further increasing Mg concentration. The Hall results display that the hole concentration gradually increases with increasing Mg dopant concentration, and the carrier mobility first increases with x increasing from 0.04 to 0.12, while decreases with x further increasing from 0.12 to 0.20. A high magnitude of optical transmittance near 60% in the visible region and wide optical bandgaps (3.41–3.66 eV) of the AgCr1−xMgxO2 thin films are observed. The facial fabrication of ACO thin films in an open condition will provide a start for the synthesis of Ag-based delafossite thin films.

Preparation of antiperovskite thin films is challenging work due to their complex phase diagram and easy decomposition during processing, which hinder the fundamental studies and applications. Herein, we report the preparation of antiperovskite CuNCo3 (CNC) thin films on several different single crystal substrates by chemical solution deposition. The results show that the derived CNC thin films are c-axis oriented regardless of the substrate orientation, suggesting the self-assembled c-axis orientation. The microstructures as well as the physical properties are investigated, showing that the CNC thin films are metallic and can be considered as a new type of soft-magnet with a ferromagnetic Curie temperature higher than 650 K. The results will provide an effective route for fabricating antiperovskite cobalt-based thin films as well as provide a prototype for the investigation of the growth mechanisms of complex metal nitride thin films by solution methods.

Epitaxial antiperovskite superconducting CuNNi3 thin films have been grown by chemical solution deposition. The film is a type II superconductor and shows a Tc of 3.2 K with a transition of 0.13 K. The Hc2(0) and ξ0 are estimated to be 8.1 kOe and 201 Å, respectively.

Transparent conducting p-type Bi2Sr2Co2Oy thin films have been first grown on SrTiO3 substrates by a chemical solution deposition, showing c-axis self-orientation. The figure of merit can reach as high as 800 MΩ−1, which is the highest value for p-type transparent conducting thin films by solution methods.

As the most-studied multiferroic material, (111)-oriented BiFeO3 (BFO) thin films are desirable due to the highest polarization in the (111) plane. The difficulty of achieving large-area (111)-oriented BFO films on silicon wafers towards implementation with silicon technology has hindered the development of BFO films. Herein, we report the annealing temperature effects on chemical solution deposition (CSD) derived BFO films on Pt(111)/Ti/SiO2/Si substrates without any buffer layer. The derived BFO films shows a strong (111) orientation with a distorted rhombohedral structure and R3c space group. The annealing temperature effects on the microstructures as well as the properties were investigated. A dense and crack-free surface was obtained in the low-temperature annealed films. Relatively high room-temperature remnant polarization 2Pr (120–140 μC cm−2) could be obtained with low leakage (∼10−5 A cm−2 at 200 kV cm−1). Scanning electron microscopy and transmission electron microscopy showed that this is an available route for fabricating large-area (111)-oriented BFO films on silicon-based wafers with high 2Pr using low-cost solution processing.

Polycrystalline La2NiMnO6 thin films are prepared on Pt/Ti/SiO2/Si substrates by the sol–gel method. Through controlling the processing parameters, the cation ordering can be tuned. The disordered and ordered thin films exhibit distinct differences for crystal structures as well as properties. The crystal structure at room temperature characterized by X-ray diffraction and Raman spectra is suggested to be monoclinic (P21/n) and orthorhombic (Pbnm) for the ordered and disordered thin films, respectively. The ferromagnetic–paramagnetic transition is 263 K and 60 K for the ordered and disordered samples respectively, whereas the saturation magnetic moment at 5 K is 4.9 μB fu−1 (fu = formula unit) and 0.9 μB fu−1. The dielectric constant as well as magnetodielectric effect is higher for the ordered La2NiMnO6 thin films. The magnetodielectric effect for the ordered thin film is dominantly contributed to the intrinsic coupling of electric dipole ordering and fluctuations and magnetic ordering and fluctuations, while it is mainly contributed to Maxwell–Wagner (M–W) effects for the disordered thin film. The successful achievements of ordered and disordered polycrystalline La2NiMnO6 thin films will provide an effective route to fabricate double-perovskite polycrystalline thin films by the sol–gel method.

Bi2Sr3Co2Oy thin films are prepared on SrTiO3 (100), (110) and (111) single crystal substrates using the sol–gel method. All the thin films are c-axis oriented regardless of the orientation of the substrate suggesting self-assembled c-axis orientation, and X-ray photoelectron spectroscopy results give evidence of coexistence of Co3+ and Co2+ ions in the derived films. Transmission electronic microscopy observations reveal that all samples are c-axis oriented with no obvious differences for different samples, and the c-axis lattice constant is determined as ∼15 Å suggesting the misfit structure. A phenomenological thermodynamic phase diagram for self-assembled c-axis orientation is established for misfit cobaltate-based films using chemical solution deposition. All samples behave like semiconductors due to the coexistence of Co3+/Co2+ ions, and the resistivity at 350 K is ∼47, 39 and 17 mΩ cm for the thin films on SrTiO3 (100), (110) and (111), respectively, whereas the Seebeck coefficient at 300 K is 97, 89 and 77 μV K−1. The successful attainment of Bi2Sr3Co2Oy thin films with self-assembled c-axis orientation will provide an effective prototype for investigation of growth mechanisms in complex oxide thin films with a misfit structure.