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Computational Study of Perovskite Structured CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> and CH<sub>3</sub>NH<sub>3</sub>SnI<sub>3</sub>
摘要： Nowadays, Hybrid Perovskite materials perform a major role in solar cell industry due to their superior power conversion ability. CH3NH3PbI3 is the prominent material in hybrid perovskite, where they comprised with advanced photovoltaic properties. But considering the toxicity, it’s more important to observe the role of metal atom in hybrid perovskite. Therefore, this research is basically focused on the objective of figuring out the fundamental properties of CH3NH3PbI3 and CH3NH3SnI3 with the idea of replacing Pb to Sn in future. Ab-Initio Simulation has been used throughout this research along with basic density function theories (DFT) like Exchange correlation functional, Local-density approximation of Kohn-Sham theory. Moreover, the research was also focused upon the Energy band gap variation, crystallographic orientations, density of states in P, S orbitals of cubic and tetragonal phases in CH3NH3PbI3 and CH3NH3SnI3.
关键词： Energy Bands,Methyl ammonium Tin Iodide perovskite,Density Function Theory,Methyl ammonium lead Iodide,Perovskite structure
更新于2025-09-23 15:23:52
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Analogous Anti-Ferroelectricity in Y2O3-Coated (Pb0.92Sr0.05La0.02)(Zr0.7Sn0.25Ti0.05)O3 Ceramics and Their Energy-Storage Performance
摘要： Antiferroelectric analogous (Pb0.92Sr0.05La0.02)(Zr0.7Sn0.25Ti0.05)O3 (PSLZSnT) ceramics were prepared by the solid-state sintering method by introducing a Y2O3-coating via the self-combustion method. The synthesized Y2O3-doped PSLZSnT ceramics present pseudo-cubic structure and rather uniform microstructural morphology accompanied by relatively small grain size. Excellent energy-storage performance is obtained in the Y2O3-doped PSLZSnT ceramics, in which the value of the energy-storage density presents a linearly increasing trend within the electric field measurement range. Such excellent performance is considered as relating to the rather pure perovskite structure, high relative density accompanied by relatively small grain size, and the antiferroelectric-like polarization-electric field behavior.
关键词： oxide doping,self-combustion method,energy-storage density,perovskite structure,PSLZSnT antiferroelectric-like ceramics
更新于2025-09-23 15:23:52
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Effect of Ni substitution on the structural and optical properties of SrZr1-xNixO3 (0.05≤x≤0.20) perovskites
摘要： Ni2+ substituted SrZr1-xNixO3 (x = 0.05, 0.10, 0.15, 0.20) perovskites are synthesized by the solid-state reaction method. Their structural, morphological and optical properties are characterized using X-ray diffraction (XRD), scanning electron microscopy with attached energy dispersive spectroscopy (SEM-EDS), UV-Visible (UV-Vis) and photoluminescence spectroscopy (PL). The XRD patterns of all the samples show the formation of a single phase, i.e. orthorhombic phase, which is further confirmed by Rietveld refinement. Structural ordering increases with an increase in the concentration of Ni2+ substitution with an increase in the mean crystallite size. The optical band gap of all the samples is in the insulating range, i.e., around 5 eV. The intensity of the PL spectra decreases with substitution concentration due to the quenching effect.
关键词： Rietveld refinement,Photoluminescence,Band gap,Perovskite structure
更新于2025-09-23 15:22:29
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Effect of the occupation of Ba and Ti sites on the structural, optical and dielectric properties of Sm-doped BaTiO3 ceramics
摘要： Sm-doped BaTiO3 powders have been synthesized with the help of the sol gel process. X-ray diffraction (XRD) patterns of the obtained powders, heat treated at a relatively low temperature (750 °C/3 h), revealed their crystallization in the pure perovskite structure without the presence of secondary phases. The occupation of the Ba and Ti sites by Sm in the BaTiO3 lattice and the evolution of the crystalline parameters as functions of the dopant content have been discussed based on XRD and Raman results. Dielectric measurements performed on the samples revealed a strong increasing diffuse character of the ferro-to-paraelectric phase transition with increasing Sm content. Moreover, the behavior of the permittivity as a function of frequency indicates that the samples are approaching their resonance frequency. The study of the conductivity showed the existence of a weak positive temperature coefficient of resistivity (PTCR) effect.
关键词： Sm-doped BaTiO3,dielectric properties,PTCR effect,perovskite structure,sol gel process
更新于2025-09-23 15:21:01
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(Ba,Sr)LaZnTaO6:Mn4+ far red emission phosphors for plant growth LEDs: structure and photoluminescence properties
摘要： It is necessary to develop novel high-efficient red or far-red-emitting in order to facilitate the phosphor-converted light-emitting diodes (pc-LEDs) for plant growth. This work reports a series of novel far-red emitting (Ba,Sr)LaZnTaO6:xMn4+ phosphors with double perovskite structure synthesized by traditional high-temperature solid-state reaction (SSR) process. The crystal structure and morphology of (Ba,Sr)LaZnTaO6 are investigated by high-resolution TEM, SEM, and XRD Rietveld refinement. The photoluminescece properties are systematically explored and analyzed by diffuse reflection (DR) spectra, photoluminescence emission (PL) and excitation (PLE) spectra, decay curves and temperature-dependent spectra. Mn4+ ions occupy Ta5+ sites located at [TaO6] octahedral emitting red light with peak at 698 nm in BaLaZnTaO6:Mn4+ and 695 nm in SrLaZnTaO6:Mn4+ under n-UV and blue light excitation. The critical quenching concentration of Mn4+ was determined to be 0.008. The concentration quenching mechanism could be a dipole-dipole interaction between Mn4+ ions. In addtion, the PL intensity of (Ba,Sr)LaZnTaO6:xMn4+ phosphors decrease with increasing temperature. The SrLaZnTaO6:xMn4+ sample has better thermal stability than BaLaZnTaO6:xMn4+. Interestingly, (Ba,Sr)LaZnTaO6:0.008Mn4+ exhibits outstanding internal quantum efficiency (IQE ≥ 80 %). Fianally, the fabricated of LEDs are combined with SrLaZnTaO6:0.008Mn4+ phosphors combined with 460 nm InGaN chips, which emit blue and red light. Based on above properties, the rare-earth-free (Ba,Sr)LaZnTaO6:xMn4+ phosphors have great potentials to be serviced as far-red emitting phosphors in high-power plant growth LEDS.
关键词： double perovskite structure,phosphor-converted light-emitting diodes,internal quantum efficiency,far-red emitting,plant growth,Mn4+,thermal stability,photoluminescence,solid-state reaction
更新于2025-09-23 15:19:57
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Influence of additives on structure and ferroelectric properties of NBT-BT-BMT ceramics
摘要： Influence of various over stoichiometric additives on phase formation, unit cell parameters, microstructure, dielectric and ferroelectric properties of solid solutions 0.8[0.8(Na0.5Bi0.5)TiO3-0.2BaTiO3]-0.2Bi(Mg0.5Ti0.5)O3 system has been studied. The unit cell volume slightly decreased in case of the V2O5 additives but did not change in case of Bi2O3, LiF, and KCl additives. Increase in dielectric parameters ert and tandrt values at the room temperature was revealed for compositions doped by KCl additives, while these parameters decreased in compositions doped by the V2O5 additives. Linear correlation between piezoelectric coefficient d33 measured for separate grains using the Piezoresponse Force Microscopy method and dielectric permittivity ert values at the room temperature was confirmed.
关键词： ferroelectric phase transitions,additives,dielectric properties,perovskite structure,Ceramics (Na0.5Bi0.5)TiO3 - BaTiO3 - Bi(Mg0.5Ti0.5)O3
更新于2025-09-10 09:29:36
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Electric and Optical Properties of Pb(Er1/2Nb1/2)-Pb(Mg1/3Nb1/3)-PbTiO3 Crystals
摘要： New ferroelectric crystals Pb(Er1/2Nb1/2)-Pb(Mg1/3Nb1/3)O-PbTiO3 (PEN-PMN-PT) were grown by using the flux method. Phase structure of the crystals was described by the X-ray diffraction analysis. Dielectric, ferroelectric and optical properties of the PEN-PMN-PT crystals were investigated systematically. Higher Curie temperature (Tc ~291 °C) and larger coercive field (Ec ~17.6 kV/cm) for the 40PEN-13PMN-47PT can be obtained, respectively, compared with those of the PMN-PT. Moreover, strong green and red emissions can be excited by using the 980 nm laser. The PEN-PMN-PT crystals with these performances have some promising applications in the electromechanical and optical devices.
关键词： Pb(Er1/2Nb1/2)-Pb(Mg1/3Nb1/3)O-PbTiO3,electric and optical properties,UC emission mechanisms,Perovskite structure
更新于2025-09-10 09:29:36
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Energy gap variation due to Al content in SmFe1? x Al x O3 and its application in optics
摘要： The optical properties of Al-doped SmFeO3 (SmFe1?xAlxO3, for x varying from 0 to 0.15), were monitored by diffuse re?ectance spectroscopy (DRS). The diffuse re?ectance spectra were used to study the surface properties of the samples. The DRS spectra exhibit three re?ection bands at different regions. The product was characterised by X-ray diffraction to con?rm the formation of single-phase crystals of the perovskite structure. The bandgap, a major factor in determining the optical performance of any material, was found to be tunable with Al content (x).
关键词： diffuse re?ectance spectroscopy,optical properties,bandgap,Al-doped SmFeO3,perovskite structure
更新于2025-09-10 09:29:36
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Preparation and Characterization of Ba1-xSrxTiO3 by Sol-Gel Method
摘要： Barium strontium titanate (BST) with formula (Ba1-xSrxTiO3) has been synthesized by sol-gel method with different stoichiometric compositions (x = 0.3, 0.4, 0.5, 0.6). The raw materials which used to prepare compounds are (Ba,Sr) acetate as a source (Ba,Sr) and titanate isopropoxide source. The FE-SEM images showed that the particles size reduced from 464 to 13 nm when strontium concentration increased from 0.3 to 0.6. The X-ray diffraction studies have confirmed that Ba0.7Sr0.3TiO3 sample have the tetragonal phase while remaining samples have a cubic phase. The intensity of the major peaks were decreased and shifted toward higher 2θ angles when Sr2+ ions increases.
关键词： Barium strontium titanate,Curie Temperature,Ferroelectric materials,Perovskite structure
更新于2025-09-04 15:30:14