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A wide range of labeling and complete attention of perovskite materials, for example layered type perovskite acting as photocatalysts, is relatively lacking. Finally, this chapter is based on the current progress and expansion of perovskite photocatalytic applications under solar energy consumption.
Results and discussion
Details of perovskite oxide materials .1 Perovskite frameworks
After a brief overview of the wide-ranging structure of perovskite oxides, it was stated that perovskites act as a photocatalyst that is incorporated, arranged and explored based on preparation methods [29, 34], photophysical properties based on band gap energies, morphology-based structures, and the photocatalytic activities depend on either the UV energy or the visible light guide energy. After a brief overview of the wide-ranging structure of perovskite oxides, it was stated that perovskites act as a photocatalyst that is incorporated, arranged and explored based on preparation methods [29, 34], photophysical properties based on band gap energies, morphology-based structures, and the photocatalytic activities depend on either the UV energy or the visible light guide energy.
Perovskite systems for photocatalysis
Moreover, to the overall ABO3 system, additional characteristic polymorphs of the perovskite system are the Brownmillerite (BM) (A2B2O5) framework . In the case of replacement of A-site ions with cations of lower oxidation states, consequences develop in oxygen-poor materials with new frameworks such as A1−mAmIBO3−x.
Photocatalytic properties perovskite oxides
Magnetic BiFeO3, known as one of the perovskite materials with many ferric in magnetoelectric properties, was also examined as a visible light photocatalyst for the photodegradation of organic pollutants due to its small band gap energy (2.2 eV) [70-79]. The 3D hierarchical Bi0.5Na0.5TiO3 showed very high photocatalytic activity for the decomposition of methyl orange dye due to the adsorption of dye molecules and larger surface area.
Photocatalytic activity of layered perovskite materials
UVA and visible light-driven photocatalytic activity of three-layer perovskite Dion-Jacobson phase CsBa2M3O10. Synthesis of LaCoO3 nanoparticles by microwave process and their photocatalytic activity under visible light irradiation.
The basic structure of perovskites
In an ideal perovskite such as SrTiO3 , CsSnBr3 , etc., there is no such distortion in the unit cell. In the case of the perovskite structure (close-packed), the A-cation must fit into four BX6 octahedra.
Application of Pb-free perovskites from a different aspect of environmental
- Perovskites as solid oxide fuel cells
- Perovskites as sensor .1 Perovskites as glucose sensor
- Perovskites as solar cell materials
- Removal of heavy metals from wastewater
Recently, the inorganic perovskite-type oxide nanomaterials have been widely applied in the processing of chemically modified electrodes [ 16 , 17 ]. In fact, about 1 million different dyes are found in the market  and about 700,000 tons of artificial dyes are produced per year .
Here this chapter ends with various applications such as SOFC, sensors, solar cells, wastewater treatment of lead-free perovskite materials. Performance improvement of lead-free tin-based perovskite solar cells with atmosphere-assisted reducing scattering additives.
Synthesis of nano-crystalline perovskites
- Solvent-induced precipitation
- Ligand assisted reprecipitation (LARP) technique
- Hot injection method
- Template-assisted method
- Emulsion method
At the nanometer scale, crystal surface defects can be readily passivated by ligands. A critical point for hot injection is the reaction temperature which affects the size of the NPSs.
Form factor of perovskite nano-crystals 1 Crystal shape of perovskite nano structures
Geometry of perovskite nano-crystals
Applications of perovskite nanoparticles 1 Optical properties of perovskite nanoparticles
High quantum efficiency
Perovskites are considered superior light emitters due to their large absorption coefficients and high quantum yield [ 59 , 60 ]. High quantum yields (90%) have been reported in inorganic ABX3 and organic-inorganic methyl ammonium halide perovskite nanocrystals without further surface treatment [ 26 , 34 ].
Quantum confinement effect
The high quantum yield usually indicates that most of the absorbed photons are transformed by radiative recombination processes. In perovskite, where there are very few electric charge trapping states, high quantum efficiency results from the formation of a distinct band gap that greatly supports exciton radial recombination efficiency .
Linear absorption and emission
Optical absorption and emission characteristics of a semiconductor can be adjusted by changing the size of the semiconductor. It is possible to adjust the bandwidth by changing the individual components of the metal halide perovskites (MHP).
Optoelectronics applications of perovskite 1 Optical lasing
Light emitting diodes
Metal halide perovskite has great potential due to its easy preparation, low cost, and high-performance light-emitting diodes. As a result, perovskite has great potential for lighting and display applications as a new generation LED material.
Perovskites in LED applications exhibit high color purity, typically 15–25 nm full-width half-color purity for electroluminescence spectra. The performance of perovskite nanosheets in LED applications was lower than the quantum dots (Figure 13c).
Organic inorganic perovskite materials in solar cells
12] developed the first stable PSC, using CH3NH3PbI3 based liquid iodide electrolyte yielding a PCE of 6.5%. To avoid the problem of dissolving perovskite in an electrolytic solution, the liquid electrolyte was replaced by a solid in 2012 and a PCE of 9% was achieved, demonstrating good stability up to 500 hours without significant losses [13, 14].
Device architecture of perovskite solar cells
The emergence of organic-inorganic perovskite-based solar cells has led to rapid growth in the history of photovoltaics. Organic-inorganic perovskite materials have recently attracted more attention due to their outstanding light-harvesting properties .
Structure of perovskite materials
The mesoporous TiO2 layer played an important role in the electron transfer process and as a scaffold providing mechanical support to the perovskite crystal. The currently mesoporous structure of PSCs is one of the most common structures with an energy conversion efficiency (PCE) greater than 20% .
Synthesis of inorganic–organic solar cells materials
One-step precursor solution deposition (spin-coating technique)
In order to obtain a layer with the desired thickness, optimization of various parameters such as concentration of perovskite solution and spin-coating parameters (spin speed, acceleration and spin duration) can be performed. The usually used solvents for spin coating technique are Dimethylformamide (DMF) or Dimethylsulfoxide (DMSO) .
Spin-coating allows the deposition of hybrid perovskites on various substrates containing glass, quartz, plastic and silicon. The spin-coating technique does not involve complicated equipment, and it produces high-quality films in a very short time at room temperature.
Thermal evaporation technique
However, deposition of organic-inorganic perovskite materials is often challenging due to different physical and chemical properties of the organic and inorganic parts of perovskite materials . After ablation, the organic and inorganic parts are reassembled on the substrates to yield films of the chosen product.
Advances in perovskite solar cells
MA/FA compounds show remarkable PCEs and therefore the development of these compounds is an opportunity in the development of PSCs. Meanwhile, the combination of Cl/Br to iodide-based structure has significantly promoted the charge transport and separation kinetics in the perovskite layer.
Toxicity and stability issue 1 Lead: the toxicity problem
However, the insulating aspect of the organic cations with poorer charge transport resulted in a lower PCE compared to 3D perovskites. It was noticed that replacing MA with Cs and FA resulted in improved photostability of the PSCs.
Conclusion and perspective
Fabrication of organolead iodide perovskite solar cells with niobium-doped titanium dioxide as compact layer. An efficient guanidinium isothiocyanate additive for improving the photovoltaic performance and thermal stability of perovskite solar cells.
SEM images of mixed perovskites and optical microscope images of CH3NH3PbX3 grown perovskites (from X = Br to Cl). The chloride content causes a decrease in the crystal size of mixed perovskites.
Synchrotron X-ray diffraction studies
In the first case, the splitting of the unit cell parameters with respect to the cubic ap is significantly lower than in the second case. This fact may explain the previous description in tetragonal symmetry in this short temperature range.
Neutron diffraction studies
These core densities support that the MA units are delocalized to the A site of the perovskite. For x and 1, the unit cell experiences a contraction, maintaining a constant slope when Cl is introduced, with MA oriented in the same direction.
As already mentioned, an interesting feature is that the compositional evolution of the band gap energy (Eg) does not show a linear behavior; it seems that the deviation from linearity is reminiscent of that revealed for the variation of the unit cell parameters at KT (see Fig. 12). The effect of the optical power densities under illumination at 505 nm in the IV curves is plotted in Figure 13b.
Atomic structure of metal halide perovskites from first principles: the chicken-and-egg paradox of organic-inorganic interactions. 19], the phase diagram of the CaO-TiO2 system in the high-temperature region is shown in Fig. 1.
The thermodynamic properties of perovskite solid phase
The present work is devoted to the review of experimental data on the thermodynamic properties of perovskite in the condensed state, as well as the gas phase components on the perovskite and its melting at high temperatures. 28] using adiabatic calorimetry deviate negligibly (up to 7 kJ/mol) in the enthalpy values of (HT-H298) in the temperature range above 1000 K.
Melting of perovskite
As seen in Figure 4, the values of oxide activities in perovskite determined via Knudsen effusion mass spectrometric method agree with each other in the investigated temperature range. As the temperature grows, there is a slight tendency towards the higher activities of calcium and titanium oxides in the crystalline perovskite phase.
The thermodynamic properties of perovskite melts
Temperatures, enthalpies and entropies of melting of compounds in the CaO-TiO2 system (calculated for 1 mol of compound). The thermodynamic properties of CaO-TiO2 melts at 2278 K  (chemical potentials of the oxides and the energy of mixing (a), partial enthalpies of the oxides and enthalpy of formation (b), and partial entropies of the oxides and the entropy of formation (c)); symbols: (1) CaO, (2) TiO2, (3) integral.
The gas phase over perovskite
Zakharov and Protas  studied the ion emission from the perovskite surface under the action of laser radiation and identified the ion of a complex molecule (CaTiO3) in addition to ions of simple oxides (O+, Ca+, CaO+, Ti+, TiO+) in the vapor mass spectra. The partial vapor pressures of (Ca), (TiO), (TiO2) and (O) over the perovskite at 2150 K were calculated using the thermochemical data of  and are shown in Figure 7 as a function of inverse temperature (for ease of understanding, the temperature scale is appropriately scaled).
Experimental produces 1 Preparing ZnO nanoparticles
Fabrication of ZnO nanoparticles doped BCZT ceramics at low sintering temperature
Among the commonly used dopants, ZnO (in the nano- or microscopic) is known as an effective sintering aid to improve the density and electrical properties of piezoceramics [12–14]. In this work, the effects of ZnO nanoparticles as well as the sintering temperature on the structure, microstructure and some electrical properties of the composition 0.48Ba(Zr0.2Ti0.8)O3-0.52(Ba0.7Ca0.3)TiO3 or BCZT were presented in detail.
Results and discussion
Structure, microstructure, and electric properties of BCZT/x ceramics sintered at temperature of 1350°C
Figure 2(a) shows the X-ray diffraction patterns of BCZT/x ceramics at different ZnO nanoparticle contents measured at room temperature. To put it more clearly, the Raman spectrum of the BCZT/x ceramic at room temperature was recorded and analyzed (Figure 8).
Influence of sintering temperature on structure, microstructure, and piezoelectric properties of doped BCZT ceramics
In addition, both grain size and density of BCZT/0.00 and BCZT/0.15 samples increased as the sintering temperature increased (Figure 16). SEM images of BCZT/0.15 (yellow border) and BCZT/0.00 (red border) ceramics sintered at different temperatures.
Improved piezoelectric properties of (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 lead-free ceramics by optimizing calcinations and. Structure, microstructure and dielectric properties of lead-free BCT-xBZT ceramics near the morphotropic phase boundary.
Passive and wireless temperature sensor design
Presentation of the gallery modes
The sensor proposed in this chapter represents an interesting technological solution for temperature detection and thus enables extremely low consumption compared to conventional techniques. This new, highly integrated device requires no onboard power supply and uses electromagnetic transduction to measure temperature.
Advantages of gallery modes for temperature detection
The energy in the gallery states has the peculiarity of being confined in a region close to the air-dielectric interface. First of all, the dimensions of the resonator excited in a gallery mode are much larger than in the case of conventional TE or TM modes.
Sensor based on millimeter band resonant gallery modes
In addition, it is important to note that the gallery modes have the peculiarity of lacking energy in the center of the resonator. Finally, these modes are no longer stationary but progressive when the resonator is excited by a progressive wave source whose propagation constant is close to that of the gallery mode.
Study of the geometric parameters of the sensor
The detection principle is then based on changing the resonance frequency of the gallery modes in the dielectric resonator. This detector is based on the direct change of the dielectric properties of the resonator in the presence of a gas.
Sensor interrogation method
A high sensitivity of the electromagnetic propagation to the environment used to perform the sensor function. A more flexible choice of operating frequency that can be adapted to the various operating constraints of the sensor.
Simulation results of the complete sensor
This sensitivity represents that of the electromagnetic transducer, which converts a variation in permittivity into a variation in the resonant frequency of a WGM. As a result, a temperature variation usually results in a shift in the resonant frequency of the excited state in the dielectric resonator.
Application of the sensor for marine fire detection
In the second part of this chapter, we presented some of the results obtained. The main reasons for this are:. i) the presence of a built-in electric field, produced by the piezoelectric effect in the layer [1, 4, 5] and (ii) the difference in arsenic segregation at the inverse interface.
Different substrate orientations show different surface states, which are expected to affect the growth mode and even the optical and electrical properties of the epilayers. As a result, it contributes to the wave formation of the InAlAs band gap from which the localized energy level is present.
Results and discussions 1 Photoluminescence study
In the growth of the high index plane (311), the PZ field and an internal field are along the same direction (A polarity) [18, 19]. From the aspect of surface kinetics, it is possible to understand this difference in the variation of the PZ field with the V/III ratio for the (311) A and (311) B orientation.
Electromechanical interaction of piezoelectric materials 1 Mechanical-electrical behavior relations
Piezoelectric actuators and sensors .1 Piezoelectric actuators
The imposed electric field E produces the -eE voltage in the piezoelectric material according to the reverse voltage effect. The first type, the piezoelectric layers or the piezoelectric patches act as actuators, which are called the piezoelectric actuators.
Static and dynamic analysis of laminated composite beams with piezoelectric layers
Displacement and strain
Finite element equations