An ab-initio study of electronic and optical properties of RhXO3 (X = Ga, Ag) perovskites

The ab-initio computations were performed to study the electronic and optoelectronic properties of RhXO3 (X = Ga, Ag) using WIEN2k code. The RhGaO3 has band gap of 2.29 eV, and the behavior of RhAgO3 metallic. The sub-TDOS of the studied materials revealed that rhodium and oxygen atoms have significant contributions in the valence band and conduction band formation of both materials. The silver cation is responsible for the reasonable peaks appearing at the Fermi level of RhAgO3, which demonstrated the conducting nature of RhAgO3. The dielectric functions, optical conductivity, energy loss function, absorption coefficient, refractive index, extinction coefficient, and reflectivity are computed for these materials to understand the optical behavior of the studied materials. The analysis of optical properties ensure the RhGaO3 is a promising material for optoelectronics while RhAgO3 has metallic nature.

Analysis of Electro-Optical Behavior in Liquid Crystal Cells with Asymmetric Anchoring Strength

Liquid crystal director distributions have been numerically analyzed between asymmetric anchoring surfaces, that is, infinitely strong and very weak anchoring strength interfaces. In a hybrid aligned nematic (HAN) cell and a twisted nematic (TN) cell, HAN and TN orientations turn to a homogeneous orientation when the weak anchoring strength is lower than a critical one. Relationships between the anchoring strength and elastic constants of the liquid crystal were analyzed to be of a quasi-homogeneous orientation. The quasi-homogeneous orientation returned to the original HAN and TN orientations under voltage application. Low-driving electro-optical properties with no threshold voltage can be obtained in a quasi-homogeneous HAN cell. A unique voltage–transmission curve of 0–100–0% appeared in a quasi-homogeneous TN cell between the crossed polarizers.

Investigation of Metastable Low Dimensional Halometallates

The solvothermal synthesis, structure determination and optical characterization of five new metastable halometallate compounds, [1,10-phenH][Pb3.5I8] (1), [1,10-phenH2][Pb5I12]·(H2O) (2), [1,10-phen][Pb2I4] (3), [1,10-phen]2[Pb5Br10] (4) and [1,10-phenH][SbI4]·(H2O) (5), are reported. The materials exhibit rich structural diversity and exhibit structural dimensionalities that include 1D chains, 2D sheets and 3D frameworks. The optical spectra of these materials are consistent with bandgaps ranging from 2.70 to 3.44 eV. We show that the optical behavior depends on the structural dimensionality of the reported materials, which are potential candidates for semiconductor applications.

Thermal and optical behavior of novel phosphate-based inorganic mixtures containing Fe and Na and their application as solar reflective coating

Herein, the synthesis of the novel and inexpensive phosphate mixtures (calcined and non-calcined) of iron (Fe) and sodium (Na) and their application as reflective coating with building envelope materials is reported. The main objective of this work is to determine the effect of hydrated mixtures as a reflective coating. To obtain different hydrated mixtures, samples were synthesized as both calcined and non-calcined mixtures. Various measurement techniques were used to characterize and study the thermal behavior of mixtures. From the thermal behavior of the mixtures, it is noticed that the mixtures can be used as heat-dissipating materials. The average crystallite size was found 40.18 nm and 25.48 nm for the calcined and the non-calcined mixtures, respectively. The calculated band gap for the calcined mixture is 3.71 eV and the non-calcined mixture is 3.73 eV. According to Reddy's equation, the refractive index of the calcined and the non-calcined mixtures is 2.61 and 2.60, respectively. Both the calcined (1A) and the non-calcined (1B) mixtures were fabricated with commercial white paint to develop aesthetic light gray coatings. Both coatings were painted and tested on two building material slabs separately. Then, the highest reflective coating material between these two was painted on a house prototype and tested against commercial gray paint available in the market. An average temperature reduction of 3.8 K was observed in modified gray coating compared to commercial building paint. The reflective coating of the calcined mixture blended with white paint was observed to be better than the non-calcined mixture blended with white paint.