The increasing energy consumption in buildings due to cooling and heating, accounting for over one-third of the total energy consumption in society, has become a growing concern. Therefore, reducing building energy consumption has become an urgent issue for countries worldwide. Windows serve as the primary channel for energy exchange between the indoor and the outdoor environments. While providing natural lighting for occupants, windows are also the weakest link in terms of energy consumption. In recent years, there have been some new and superior coating glass technologies compared to traditional low-emissivity glass. These coatings utilize various optical functional materials to regulate the incident sunlight, aiming to save cooling and heating energy consumption. Materials, such as tungsten-based compounds, vanadium dioxide, lanthanum hexaboride, or copper monosulfide, can absorb near-infrared light to effectively control solar radiation by leveraging the localized surface plasmon resonance (LSPR) effect of nanoparticles. This paper mainly introduces the micro-mechanisms of these materials and provides a detailed summary of the latest advancements in coating materials. The application and effects of these coatings in building energy conservation are emphasized. Finally, the challenges and prospects of LSPR-based smart windows are discussed. It is expected that this review will provide new insights into the application of smart windows in green buildings.

The transition-metal based alloy system YNi _4-xCo _xSi shows a second-order ferromagnetic-to-paramagnetic transition near room temperature. Here, the magnetic structure, the magnetocaloric properties and the magnetic anisotropy of YNi _4-xCo _xSi (x = 0–4) are investigated. For x = 3.5, 3.75 and 4.0 a Curie temperature near room temperature is observed with T _C = 250, 283 and 310 K, respectively. In orientated YNi _4-xCo _xSi powder samples the c axis of the hexagonal crystal structure is found to be the easy magnetic axis, with a large dominant K ₂ anisotropy constant (K ₂ > K ₁ > 0). The magnetic structure and the preferred atomic position for Ni are demonstrated by neutron diffraction measurements. We have found a dramatic decrease in the magnetic moment at the 3 g site in the CaCu ₅-type structure (space group P6/mmm), the saturation magnetization and the Curie temperature with increasing Ni concentration.

Mn compounds presenting magneto-structural phase transitions are currently intensively studied for their giant magnetocaloric effect; nevertheless, several parameters remain to be further optimized. Here, we explore the Mn(Fe,Ni)(Si,Al) series, which presents two advantages. The Mn content is fixed to unity ensuring a large saturation magnetization, and it is based on non-critical Si and Al elements instead of the more commonly employed Ge. Structural and magnetic properties of MnFe_0.6 Ni_0.4 Si_1-x Al_x compounds are investigated using powder X-ray diffraction, SEM, EDX, DSC, and magnetic measurements. We demonstrate that a magneto-structural coupling leading to transformation from ferromagnetic with orthorhombic TiNiSi-type structure to a paramagnetic hexagonal Ni₂ In-type phase can be realized for 0.06 < x ≤ 0.08. Unfortunately, the first-order transition is relatively broad and incomplete, likely as the result of insufficient sample homogeneity. A comparison between samples synthesized in different conditions (as-cast, quenched from 900^◦ C, or quenched from 1100^◦ C) reveals that Mn(Fe,Ni)(Si,Al) samples decompose into a Mn₅ Si₃-type phase at intermediate temperatures, preventing the synthesis of high-quality samples by conventional methods such as arc-melting followed by solid-state reaction. By identifying promising MnFe_0.6 Ni_0.4 Si_1-x Al_x compositions, this study paves the way toward the realization of a giant magnetocaloric effect in these compounds using alternative synthesis techniques.

While rare-earth magnets exhibit unchallenged hard-magnetic properties, looking for alternatives based on inexpensive elements of non-critical supply remains of utmost interest. Here, we demonstrate that (Fe,Co)₂(P,Si) single crystals combine a large magnetocrystalline anisotropy (K₁ ≈ 0.9 MJ m⁻³ at 300 K), high Curie temperatures (T_C up to 560 K) and an appreciable saturation specific magnetization (101 A m² kg⁻¹) leading to a theoretical |BH|_max ≈ 165 kJ m^-3, making them promising candidate materials as rare-earth-free permanent magnets. Our comparison between (Fe,Co)₂P and (Fe,Co)₂(P,Si) single crystals highlights that Si substitution reduces the low-temperature magnetocrystalline anisotropy, but strongly enhances T_C, making the latter quaternary alloys most favorable for room temperature applications. Submicron-sized particles of Fe_1.75Co_0.20P_0.75Si_0.25 were prepared by a top-down ball-milling approach. While the energy products of bonded particles are to this point modest, they demonstrate that permanent magnetic properties can be achieved in (Fe,Co)₂(P,Si) quaternary alloys. This work correlates the development of permanent magnetic properties to a control of the microstructure. It paves the way toward the realization of permanent magnetic properties in (Fe,Co)₂(P,Si) alloys made of economically competitive Fe, P and Si elements, making these materials desirable for applications.