Effect of polymer concentration on optical and electrical properties of liquid crystals for photonic applications

Mani, Santosh A.; Patwardhan, Suren; Hadkar, Sameer; Mishra, Krishnakant; Sarawade, Pradip B.

doi:10.1016/j.matpr.2022.01.057

Cited by 12 publications

(7 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Substitution of Eu 3+ at the A-site of the NBT adds extra ion at the A-site, which enhances degree disorder and compositional fluctuation and randomness in the distribution of Eu 3+ , Bi 3+, and Na 1+ at the A-site. Thus, enhanced broadness at Tm due to Eu 3+ substitution manifests that chemical-induced DPT type relaxor nature in the ceramic [11][12][13]. To illustrate the electromechanical coefficient (kp), room temperature εˈ vs frequency plot is measured for poled ceramics in the range of 20 Hz to 10 6 Hz.…”

Section: Engineering Materials: Properties and Processing Technologiesmentioning

confidence: 99%

Effect of Electrical Poling on the Structural, Dielectric, and Photoluminescence Properties of Eu3+ Substituted Eco-Friendly Ferroelectric Material Na0.5Bi0.5TiO3

Mev

Lavadiya

Raavi

et al. 2023

MSF

View full text Add to dashboard Cite

In this work, the effect of electric field on structural, photoluminescence, dielectric, and piezo/ferroelectric properties of 2.5 mole % Eu3+substituted sodium bismuth titanate (Na0.5Bi0.475Eu0.025TiO3 abbreviated as NBT-Eu) ferroelectric material has been investigated. Rietveld refinement on the X-ray diffraction patterns of poled and unpoled ceramics suggested lower monoclinic symmetry (Cc) with 93.64% as major phase fraction and higher orthorhombic symmetry (Pbnm) with 6.36% as minor phase fraction. For the poled composition, the monoclinic (Cc) phase fraction decreased to 83.53%, and the orthorhombic (Pbnm) phase fraction increased to 16.47%. Improved ferroelectric and piezoelectric characteristics in comparison to pure NBT were found in Eu3+ substituted NBT. Moreover, the substitution with Eu3+ enabled observation of photoluminescence (PL) emission in the visible region under an excitation wavelength of 532 nm for electrically poled and unpoled ceramics, thereby enabling additional functionality for this material along with ferroelectric and dielectric properties. Intensities of PL emissions were tuned by the application of electric poling of the ceramic, which generates the possibility of using these materials in optoelectronics device applications.

show abstract

Section: Engineering Materials: Properties and Processing Technologiesmentioning

confidence: 99%

Effect of Electrical Poling on the Structural, Dielectric, and Photoluminescence Properties of Eu3+ Substituted Eco-Friendly Ferroelectric Material Na0.5Bi0.5TiO3

Mev

Lavadiya

Raavi

et al. 2023

MSF

View full text Add to dashboard Cite

show abstract

“…Earlier studies were performed by some researches on those samples for which the liquid crystalline state was existing in a normal temperature range (18) . Also, In recent studies, the materials taken for investigation have their liquid crystalline state either in lower temperature range (10) , (19) or in moderate temperature range (20) but the present study shows that the maintenance of the liquid crystalline state is not only possible even on higher temperatures (90 0 C -94 0 C for Cholesteryl Propionate and 149 0 C -175 0 C for Cholesteryl Benzoate) but its tuning is also achievable (104 0 C -145 0 C for Mixture 1 to Mixture 3).…”

Section: Order Parametermentioning

confidence: 99%

Principal Polarizability and Orientational Order Parameter Study of some Pure Cholesteric Liquid Crystals and their Homogeneous Mixtures: Phase Transition Behaviour

Warsi¹,

Manohar²

2022

IJST

View full text Add to dashboard Cite

Objectives: To study the behavior of the molecular polarizabilities (α e , α o ) and order parameter (S) in various phases of Cholesteryl Propionate, Cholesteryl Benzoate and their homogeneous mixtures of weight fractions 0.25, 0.50 and 0.75. Methods: The measurement of extraordinary refractive index (n e ) and ordinary refractive index (n o ) was carried out with the help of Abbe's refractometer and modified wedge method, in the temperature range of 85 0 C-180 0 C. The anisotropic internal field model is used to calculate the internal field factor (a) and order parameter (S). Findings: The decrease in the ratio of the principal polarizabilities (α o /α e )with increase in temperature has been observed. At the transition points of solid to cholesteric (S-Ch transition) and cholesteric to isotropic (Ch-I transition), the decrease in the ratio of principal polarizabilities is much sharper for both Cholesteryl Benzoate and Cholesteryl Propionate and also for their mixtures. The value of the order parameter (S) remains constant in solid phase and sharp decrease occurs in its values for pure samples as well as their mixtures, when materials go from solid to cholesteric phase (S-Ch transition). After the S-Ch transition, the order parameter (S) goes on decreasing with further increase in temperature until the cholesteric to isotropic transition (Ch-I transition) occurs. Novelty: Some researchers have calculated the principal polarizabilities and order parameter of optically positive nematic liquid crystals and aligned cholesteric liquid crystals by using isotropic internal field model such as Vuk's approach. This itself raises the question of how can an anisotropic environment give rise to isotropic field. The present study is based on the anisotropic field model suggested by Maier and Saupe in which the internal field acting on a molecule is considered to be anisotropic. This approach used to calculate principal polarizabilities and order parameter is more realistic and gives more accurate results.

show abstract

“…There are several liquid crystal (LC) technologies and they can be based on either optical scattering or absorption. The scattering based technologies include polymer dispersed liquid crystals (PDLCs), [16][17][18][19][20][21] polymer stabilized liquid crystal (PSLC), [22][23][24][25][26][27][28][29] and polymerstabilized cholesteric textures (PSCTs). [30][31][32][33][34][35][36][37] In one state under a specific voltage condition, the liquid crystal in the window is in an optically uniform state and is transparent.…”

Section: Introductionmentioning

confidence: 99%

Smart Switchable Window with Bistability and Tunability of Transmission

Zhou,

Zhang,

Halder

et al. 2024

Advanced Optical Materials

View full text Add to dashboard Cite

Windows are used everywhere, from buildings to vehicles. Smart switchable windows are highly sought‐after in order to reduce energy consumption. An ideal smart window should have two functions. First, it should be able to control privacy. Second, it should be able to control radiant energy flow. Here, a smart window is reported that possesses the two functions. The smart window is based on a dichroic dye‐doped cholesteric liquid crystal. It exhibits two stable states in the absence of applied voltage. One of them is the planar state that is optically absorbing without haze and can control radiant energy flow. The other state is the focal conic state that is optically scattering and can control privacy. Furthermore, when voltage is applied, the liquid crystal is switched to a heliconical state, where the transmittance can be tuned continuously. Thanks to its superior performance, this smart window has a big potential for applications in architectural and vehicle windows.

show abstract

Effect of polymer concentration on optical and electrical properties of liquid crystals for photonic applications

Cited by 12 publications

References 18 publications

Effect of Electrical Poling on the Structural, Dielectric, and Photoluminescence Properties of Eu<sup>3+</sup> Substituted Eco-Friendly Ferroelectric Material Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>

Effect of Electrical Poling on the Structural, Dielectric, and Photoluminescence Properties of Eu<sup>3+</sup> Substituted Eco-Friendly Ferroelectric Material Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>

Principal Polarizability and Orientational Order Parameter Study of some Pure Cholesteric Liquid Crystals and their Homogeneous Mixtures: Phase Transition Behaviour

Smart Switchable Window with Bistability and Tunability of Transmission

Contact Info

Product

Resources

About