Noncentrosymmetric Inorganic Oxide Materials: Synthetic Strategies and Characterisation Techniques

Halasyamani, P. Shiv

doi:10.1002/9780470686072.ch1

Cited by 12 publications

(6 citation statements)

References 152 publications

(196 reference statements)

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“…Pioneering studies on the structure of perovskites were performed by Victor Goldschmidt (1926) [13]. Subsequently, several synthetic perovskites were prepared and studied [14][15]. Approximately more than 40 naturally-occurring minerals in the form of oxides, halides, hydroxides, arsenide, and intermetallic compounds have been identified in the perovskite supergroup [16].…”

Section: Perovskite Materialsmentioning

confidence: 99%

Issues, Challenges, and Future Perspectives of Perovskites for Energy Conversion Applications

Pode¹,

Muley²,

Diouf³

2023

Preprint

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Perovskite solar cells are an evolving technology owing to self-assembling and highly tunable bandgap properties of materials. In this context, thin films of perovskites have attracted immense attention and witnessed great advancement because of their low manufacturing cost. The key development in these devices is the conversion efficiency, which rose from 3.8% to 28%. The formulation of innovative materials with the proper replacement of lead in perovskites is imperative to mitigate lead toxicity. Here, we analyzed the challenges like material and structural stability, device stability under high temperature and humidity conditions, lifetime, manufacturing cost, etc. faced in the commercialization of perovskite devices. This review shows that challenges such as device engineering, performance stability against the harsh environment, cost-effectiveness, and environmental concern should be taken into consideration for the widespread acceptance of perovskite-based solar devices. In conclusion, we suggested that an enormous scope exists for exploring high-performance and long-lasting perovskites for energy applications.

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Section: Perovskite Materialsmentioning

confidence: 99%

Issues, Challenges, and Future Perspectives of Perovskites for Energy Conversion Applications

Pode¹,

Muley²,

Diouf³

2023

Preprint

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“…Another area of chemistry where symmetry and chirality are central is classical crystallography 6–14, 88–93. Inversion symmetry (usually termed centrosymmetricity in crystallography88–90) and mirror symmetry are important for understanding physical properties of crystals such as piezoelectricity, optical nonlinearity, ferroelectricity and more 91–93. Here, we concentrate on evaluating the symmetry of the unit cell of crystals (and in a subsequent article we address the evaluation of the CSM of crystals using their space groups).…”

Section: Examples: the Quantitative Symmetry And Chirality Evaluationmentioning

confidence: 99%

Quantitative symmetry and chirality—A fast computational algorithm for large structures: Proteins, macromolecules, nanotubes, and unit cells

2011

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Symmetry is one of the most fundamental properties of nature and is used to understand and investigate physical properties. Classically, symmetry is treated as a binary qualitative property, although other physical properties are quantitative. Using the continuous symmetry measure (CSM) methodology one can quantify symmetry and correlate it quantitatively to physical, chemical, and biological properties. The exact analytical procedures for calculating the CSM are computationally expensive and the calculation time grows rapidly as the structure contains more atoms. In this article, we present a new method for calculating the CSM and the related continuous chirality measure (CCM) for large systems. The new method is much faster than the full analytical procedures and it reduces the calculation time dependency from N! to N(2), where N is the number of atoms in the structure. We evaluate the cost of the applied approximations, estimate the error of the method, and show that deviations from the analytical solutions are within an error of 2%, and in many cases even less. The method is applicable at the moment for the cyclic symmetry point groups- C(i), C(s), C(n), and S(n), and therefore it can be used also for chirality measures, which are the minimal of the S(n) measures. We demonstrate the application of the method for large structures across chemistry: proteins, macromolecules, nanotubes, and large unit cells of crystals.

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“…Similarly, RP-and DJ-layered perovskite oxides consisting of the second-order Jahn−Teller (SOJT) active ions such as the lone pair containing Bi 3+ ions at the A sites and d 0 metal ions (Ti 4+ , Nb 5+ ) forming the corner-shared BO 6 units in the [A n−1 B n O 3n+1 ] blocks are expected to form the acentric and probably the polar structures. 4,22 More often the listed NCSstructured oxides are less because of the preferential crystallization of the synthesized compounds in centrosymmetric structures coupled with the difficulties in the experimental identification of the factors (e.g., BO 6 octahedral rotations, cation displacements) signifying low symmetry NCS and specifically falling in the polar category. Even in the instances, wherein the NCS polar structures were located through careful structural determination, the respective experimental confirmation of the ferroelectric behavior has turned out to be more difficult.…”

Section: ■ Introductionmentioning

confidence: 99%

Second Harmonic Generation in the Polar A′SmNb₂O₇ (A′ = Rb, Cs) Dion–Jacobson Layered Perovskites

2023

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Members belonging to the Dion−Jacobson (DJ) family of layered perovskites have time and again proven to be the preferred materials of choice for the exploration and identification of polar structures. We report two noncentrosymmetric n = 2 DJ members, A′SmNb 2 O 7 (A′ = Rb, Cs), prepared by hightemperature solid-state reactions, thus expanding the polar n = 2, DJ series as A′ANb 2 O 7 (A′ = Rb, Cs; A = La, Pr, Nd, Sm, Bi). Optical second harmonic generation measurements utilizing 1064 nm substantiated the existence of Type I phase matchable compounds, and the efficiencies were 4 to 6 times higher than the standard KDP. Structural refinements by the Rietveld method confirm the polar orthorhombic space groups of I2cm and P2 1 am, respectively, for RbSmNb 2 O 7 [a = 5.4368(3) Å, b = 5.3944(3) Å, c = 21.9051(1) Å] and CsSmNb 2 O 7 [a = 5.4669(5) Å, b = 5.4158(4) Å, c = 11.1437(1) Å]. The orthorhombic distortions and symmetry lowering were further supported by the Raman spectroscopy measurements. The difference in the orthorhombic a and b parameters (∼0.05 Å) possibly originates from the chemical pressure induced by the smaller ionic size of Sm 3+ (1.24 Å, XII) as compared to other Ln 3+ (La, Pr, Nd) ions. Ferroelectric switching of A′SmNb 2 O 7 (A′ = Rb, Cs) oxides is demonstrated by the polarization hysteresis loops observed at room temperature with remanent polarization values of 5.3 and 2.0 μC/cm 2 corresponding to the Rb and Cs analogues. Variable-temperature powder X-ray diffraction measurements confirmed the phase transition from polar to anti-polar transitions around temperatures ∼1273 and ∼1173 K, respectively, for the Rb and Cs analogues. Structural analysis results in the identification of prototype tetragonal (a ∼ 3.88 Å, c ∼ 11.20 Å) centrosymmetric structures relating the transition temperatures to potential Curie temperatures. The transitions coincide with the observed Curie point of 1113 K for CsSmNb 2 O 7 , from the temperature-dependent relative permittivity measurements, and a much higher temperature is expected for the Rb analogue.

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Noncentrosymmetric Inorganic Oxide Materials: Synthetic Strategies and Characterisation Techniques

Cited by 12 publications

References 152 publications

Issues, Challenges, and Future Perspectives of Perovskites for Energy Conversion Applications

Issues, Challenges, and Future Perspectives of Perovskites for Energy Conversion Applications

Quantitative symmetry and chirality—A fast computational algorithm for large structures: Proteins, macromolecules, nanotubes, and unit cells

Second Harmonic Generation in the Polar A′SmNb₂O₇ (A′ = Rb, Cs) Dion–Jacobson Layered Perovskites

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Noncentrosymmetric Inorganic Oxide Materials: Synthetic Strategies and Characterisation Techniques

Cited by 12 publications

References 152 publications

Issues, Challenges, and Future Perspectives of Perovskites for Energy Conversion Applications

Issues, Challenges, and Future Perspectives of Perovskites for Energy Conversion Applications

Quantitative symmetry and chirality—A fast computational algorithm for large structures: Proteins, macromolecules, nanotubes, and unit cells

Second Harmonic Generation in the Polar A′SmNb2O7 (A′ = Rb, Cs) Dion–Jacobson Layered Perovskites

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Second Harmonic Generation in the Polar A′SmNb₂O₇ (A′ = Rb, Cs) Dion–Jacobson Layered Perovskites