Sharif Digital Repository

The compatibility of atomic layer deposition directly onto the mixed halide perovskite formamidinium lead iodide:methylammonium lead bromide (CH(NH2)2, CH3NH3)Pb(I,Br)3 (FAPbI3:MAPbBr3) perovskite films is investigated by exposing the perovskite films to the full or partial atomic layer deposition processes for the electron selective layer candidates ZnO and SnOx. Exposing the samples to the heat, the vacuum, and even the counter reactant of H2O of the atomic layer deposition processes does not appear to alter the perovskite films in terms of crystallinity, but the choice of metal precursor is found to be critical. The Zn precursor Zn(C2H5)2 either by itself or in combination with H2O during... 

We report a simple synthetic approach to grow uniform CH3NH3PbI3 perovskite (PSK) layers free of pinholes via varied portions of silver iodide (AgI) added to the precursor solution. XRD/EDS elemental mapping experiments demonstrated nearly uniform Ag distribution inside the perovskite film. When the 1% AgI-assisted perovskite films were fabricated into a p-i-n planar device, the photovoltaic performance was enhanced by ∼30% (PCE increased from 9.5% to 12.0%) relative to the standard cell without added AgI. Measurement of electronic properties using a hall setup indicated that perovskite films show p-type character after Ag doping, whereas the film is n-type without Ag. Transients of... 

In this paper fabrication of a 0-3 ceramic/ceramic composite lead zirconate titanate, Pb(Zr0.52Ti0.48)O3 thin film has been presented and then a pressure sensor based on multilayer thin-film PZT diaphragm contain of Lead Zirconate Titanate nanocrystalline powders was designed, modeled and optimized. This multilayer diaphragm in general acts as sensor or actuator. ANSYS was used for simulation of diaphragm. Dynamics characteristics of this multilayer diaphragm have been investigated. By this simulation the effective parameters of the multilayer PZT diaphragm for improving the performance of a pressure sensor in different ranges of pressure are optimized. The optimized thickness ratio of PZT... 

Hydroxyapatite (HAp) nanostrips were rapidly obtained during a mild microwave heating method. Applying microwave irradiation to Ca(NO3)2·4H2O/CTAB/Na2HPO4 precursor solution, the HAp precipitation process was occurred directly and without common crystallographic transformations including dissolution and slow recrystallization. The cationic surfactant CTAB was used as a soft template to modify nucleation and growth process. TEM investigations showed that the fabricated nanostrips had a width and length of about 10 and 55 nm, respectively. The X-ray diffraction pattern revealed that the fabricated well-crystallized and high purity hydroxyapatite nanostrips had a pattern similar to the bone... 

An attempt to synthesize pyrochlore free (x)PMN-(1 - x)PZT ceramics (where x is 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1) by a mixed powder method was made. In this work, a sol-gel prepared PZT powder was mixed with the mixture of milled PbO, MgO and Nb2O5, and sintered in a two step sintering process. The produced samples with high PZT content showed low densities due to the low compaction ratio of PZT powder. The dielectric properties of PZT-rich and PMN-rich materials were high (with dielectric constant of about 19,000 and 33,000 for PZT-rich and PMN-rich ceramics, respectively) while the other samples exhibited low dielectric properties. Also, the effect of combining PMN with PZT on Curie... 

Nanostructured and mesoporous TiO2-Ga2O3 thin films with various Ti:Ga atomic ratios were prepared by a new straightforward particulate sol-gel route. Titanium isopropoxide and gallium (III) nitrate hydrate were used as precursors, and hydroxypropyl cellulose (HPC) was used as a polymeric fugitive agent (PFA) in order to increase the specific surface area (SSA). XRD and TEM analysis of the powders revealed that the Ga2O3 formed from the nitrate precursor retarded anatase-to-rutile transformation, crystallization and crystal growth. The average crystallite size of pure TiO2 powder annealed at 600-1000 °C were in the range 4-10 nm; the values that could be decreased to 2-6 nm for TiO2-Ga2O3... 

CdS nanoparticles were grown using CdSO4 and Na 2S2O3 as the precursors and thioglycerol (TG) as the capping agent. TG was shown to exhibit a catalytic role in the reaction and also acted as a capping agent. It was demonstrated that size growth is linearly related to the temperature of the reaction, i.e.the sizes can be controllably adjusted by temperature. The crystalline phase of the nanocrystals was also dependent on the temperature of growth: higher temperature favours the cubic phase. The pH also plays an important role in nanoparticle growth, as lower pH leads to a higher release rate of sulfur species. At pH as high as 10, the growth rate remains slow even at boiling temperature. This...