Uniform deposition of ultra-thin TiO_(2) film on mica substrate by atmospheric pressure chemical vapor deposition: Effect of precursor concentration

The performance of pearlescent pigment significantly affected by the grain size and the roughness of deposited film. The effect of TiCl_(4) concentration on the initial deposition of TiO_(2) on mica by atmospheric pressure chemical vapor deposition(APCVD) was investigated. The precursor concentration significantly affected the deposition and morphology of TiO_(2) grains assembling the film. The deposition time for fully covering the surface of mica decreased from 120 to 10 s as the TiCl_(4) concentration increased from 0.38%to 2.44%. The grain size increased with the TiCl_(4) concentration. The AFM and TEM analysis demonstrated that the aggregation of TiO_(2) clusters at the initial stage finally result to the agglomeration of fine TiO_(2) grains at high TiCl_(4) concentrations. Following the results, it was suggested that the nucleation density and size was easy to be adjusted when the TiCl_(4) concentration is below 0.90%.

Effects of precursor solution concentration on the properties and morphology of YBCO films deposited by TFA-MOD method

Epitaxial YBCO films were deposited on （100） LaAlO3 single-crystal substrates by metalorganic deposition of metal trifluoroacetate precursors with different concentrations. All the YBCO films have Tc around 91 K and Jc excess 2 MA/cm^2 at 77 K in zero field. XRD θ-2θscans show all the films have c-axis normal orientation. The FWHM （full width at half-maximum intensity） values of X-ray ω-scans of （005） reflection are 0.379°, 0.283°, and 0.543° for the YBCO thin films deposited with precursor solution concentrations of 1.52, 1.0, and 0.75 mol/L, respectively. With the concentration of the precursors decreasing, the thickness of the films decreases linearly. SEM micrographs show that porosities in the films become bigger with the precursor solution concentration decreasing. The big porosities in the film with the lowest concentration precursor deteriorate the superconducting property and make it have a wider superconducting transition and a lower Jc.

Effects of precursor solution concentration on dielectric properties of (Pb,La)(Zr,Ti)O_3 antiferroelectric thick films by sol-gel processing

Pb0.97La0.02Zr0.95Ti0.05O3(PLZT)antiferroelectric thick films derived from different precursor solution concentrations are prepared on platinized silicon substrates by sol-gel processing.The films present polycrystalline perovskite structure with a(100)preferred orientation by X-ray diffraction(XRD)analysis.The antiferroelectricity of the films is confirmed by the double hysteresis behaviors of polarization and double-bufferfly response of dielectric constant under the applied electrical field.Antiferroelectric properties and dielectric constant are improved while the polarization characteristic values are reduced with the increase of precursor solution concentration.The films at higher precursor solution concentration exhibit excellent dielectric properties.

Controlled growth of transition metal dichalcogenide via ther-mogravimetric prediction of precursors vapor concentration

Transition metal dichalcogenide(TMD)alloys and heterostructures are attracting increasing attention thanks to their unique electronic,optical,and interfacial properties.However,the growth fundamental of TMD alloys and heterostructures during one-step growth is still beyond understanding.Here,thermogravimetric(TG/DTG)technology is introduced to predict the evolution of the precursor(MoO_(3)and WO_(3))concentration in the vapor during growth.We establish the correlation between precursor concentration and the corresponding growth behavior.TG/DTG predication suggests that tuning precursor temperature and powder ratio can alter their concentration in the vapor,well explaining the formation of Mo_(x)W_(1-x)Se_(2) alloy or MoSe_(2)-WSe_(2) heterostructure at different growth conditions.Based on the TG/DTG analysis,we further design and grow a complex MoSe_(2)-Mo_(x)W_(1-x)Se_(2)-WSe_(2) heterostructure and Mo_(x)W_(1-x)Se_(2) monolayer alloys,confirming the validity of TG/DTG prediction in TMD crystal synthesis.Thus,employing TG/DTG to predict the synthesis of two-dimensional materials is of importance to understand the TMD growth behavior and provide guidance to the desired TMD heterostructure formation for future photoelectric devices.

Effect of molarity on sol-gel routed nano TiO_(2) thin films

The nanostructured titanium dioxide(TiO_(2))thin films have been prepared for the molar concentrations of titanium tetra isopropoxide(TTIP)0.05 M,0.1 M,0.15 M and 0.2 M by sol-gel routed spin coating technique with calcination at 450℃.The processing parameters such as,pH value(8),catalyst HCl(0.1 ml),spin speed(3000 rpm)and calcination temperature(450℃)are optimized.The crystalline nature and surface morphology were analyzed by XRD,SEM and AFM analysis.The XRD results confirm that the films are crystalline with anatase phase,and are nanostructured.The SEM micrographs of the TiO_(2) film reveal the spherical nature of the particle.AFM analysis establishes that the uniformity of the TiO_(2) thin film was optimized at 0.2 M.The optical measurements show that the transmittance depends on the molarity,and the optical band gap energy of TiO_(2) films is found to be inversely proportional to molarity.The I-V characteristics exhibit that the molarity strongly influences the electrical conductivity of the film.The results indicate that the significant effect of molarity on structural,optical and electrical properties of the nanostructured TiO_(2) thin films will be useful to photovoltaic application.

Selective synthesis and growth mechanism of CeVO_4 nanoparticals via hydrothermal method

Selective-controlled structure and shape of CeVO4 nanocrystals were successfully synthesized via a hydrothermal method from Na3VO4·12H2O and Ce（NO3）3·6H2O.The resulting products were characterized by X-ray powder diffraction （XRD）,field emission scanning electron microscopy （FESEM） and energy dispersive spectroscopy （EDS）.The influence of hydrothermal temperature,precursor solution concentration on the crystal and morphology of products were further studied.The results showed that the as-synthesized products exhibited pure single-crystal CeVO4 nanoparticles with tetragonal structure.The hydrothermal temperature and precursor solution concentration had important effects on the formation of CeVO4 nanoparticles.Furthermore,the growth mechanism of CeVO4 nanoparticles was explained with Ostwald ripening mechanism.

Active-layer evolution and （CH3NH3）3Bi2l9-based solar substrate efficiency improvement of cell on TiO2-deposited ITO

We systematically investigated the development of film morphology and crystallinity of methyl-ammonium bismuth （Ⅲ） iodide （MA3Bi2I9） through one- step spin-coating on TiO2-deposited indium tin oxide （ITO）/glass. The precursor solution concentration and substrate structure have been demonstrated to be critically important in the active-layer evolution of the MA3Bi2I9-based solar cell. This work successfully improved the cell efficiency to 0.42% （average： 0.38%） with the mesoscopic architecture of ITO/compact-TiOdmesoscopic-TiO2 （meso-TiO2）/ MA3Bi2I9/2,2＇,7,7＇-tetrakis（N,N-di-4-methoxyphenylamino）-9,9＇spiro-bifluorene （spiro-MeOTAD）/MoO3/Ag under a precursor concentration of 0.45 M, which provided the probability of further improving the efficiency of the BiB＋-based lead-free organic-inorganic hybrid solar cells.