Despite the rapid development and enormous success of organic–inorganic hybrid halide perovskites (AB′X₃), such as CH₃NH₃PbI₃ as absorbers for perovskite-based solar cells (PSCs), the commercial applications of photovoltaic techniques still face several challenges, such as decomposition when exposed to light and moisture, and lead toxicity. On the other hand, the double perovskites (A₂B′B″X₆) are derived from the AB′X₃ when half of the octahedrally coordinated B′-cations are partially replaced by the suitable B″-cations. They are attracting attention due to a new design strategy to replace Pb²⁺ ions with the couple of a monovalent M⁺ ion and a trivalent M³⁺ ion, leading to a new family of quaternary double perovskites. In this way, we aim to synthesize and characterize Cs₂AgSbCl₆ powdered samples, designed for solar cell applications. The crystalline phase and morphological features are investigated by X-ray powder diffraction (XRPD), neutron powder diffraction (NPD), scanning electron microscopy (SEM) in complement with UV–vis spectroscopy, showing a suitable band gap of 2.7 eV. The solution synthesis method proved to be efficient in obtaining polycrystalline-Cs₂AgSbCl₆ samples in a cubic ordered phase. DFT calculations also provided insights on the vibrational properties of Cs₂AgSbCl₆, corroborating the experimental data and elucidating the optical activity of Raman and infrared modes.

Thermal expansion of ${\mathrm{Li}}_{0.9}{\mathrm{Mo}}_6{\mathrm{O}}_{17}$ is $a$-axis dominated which reduces the separation of the conducting chains at low temperature enhancing the interchain coupling. This destabilizes the Luttinger-liquid fixed point leading to an electronic charge- (or spin-) density wave dominated by Coulomb repulsion, as predicted by theories for Luttinger liquids.

Methylammonium lead iodide (MAPbI₃) is an important light-harvesting semiconducting material for solar-cell devices.

Magnetic measurements of ${\text{La}}_{0.7}{\text{Ca}}_{0.3}{\text{MnO}}_3$ reveal a departure from Curie-Weiss behavior below the orthorhombic (O) to rhombohedral (R) structural transition at $T_{O-R}=705\text{K}$. Between $T_{O-R}$ and $T^{\ast }=273\text{K}$, the magnetic response is clearly paramagnetic but with an enhanced magnetic moment attributed to the existence of small ferromagnetic polarons. These polarons grow in density and begin to interact below $T^{\ast }$ as evidenced through low-field magnetic-susceptibility and field-dependent magnetization measurements, which show hysteresis and saturation, respectively. At the ferromagnetic transition temperature $T_c=247.1\text{K}$, the polarons coalesce and the system exhibits long-range ferromagnetism. It is asserted that the transition at $T_c$ should be viewed as a polaronic to ferromagnetic phase transition. The relevance of the Griffiths phase is addressed.

A new method for analyzing second-order phase transitions is presented and applied to the polaronic system ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_3$. It utilizes heat capacity and thermal expansion data simultaneously to correctly predict the critical temperature’s pressure dependence. Analysis of the critical phenomena reveals second-order behavior and an unusually large heat capacity exponent.