Magnesium hydride (MgH₂) has received outstanding attention as a safe and efficient material to store hydrogen because of its 7.6 wt.% hydrogen content and excellent reversibility. Nevertheless, the application of MgH₂ is obstructed by its unfavorable thermodynamic stability and sluggish sorption kinetic. To overcome these drawbacks, ball milling MgH₂ is vital in reducing the particle size that contribute to the reduction of the decomposition temperature. However, the milling process would become inefficient in reducing particle sizes when equilibrium between cold-welding and fracturing is achieved. Therefore, to further ameliorate the performance of MgH₂, nanosized cobalt titanate (CoTiO₃) has been synthesized using a solid-state method and was introduced to the MgH₂ system. The different weight percentages of CoTiO₃ were doped to the MgH₂ system, and their catalytic function on the performance of MgH₂ was scrutinized in this study. The MgH₂ + 10 wt.% CoTiO₃ composite presents the most outstanding performance, where the initial decomposition temperature of MgH₂ can be downshifted to 275 °C. Moreover, the MgH₂ + 10 wt.% CoTiO₃ absorbed 6.4 wt.% H₂ at low temperature (200 °C) in only 10 min and rapidly releases 2.3 wt.% H₂ in the first 10 min, demonstrating a 23-times-faster desorption rate than as-milled MgH₂ at 300 °C. The desorption activation energy of the 10 wt.% CoTiO₃-doped MgH₂ sample was dramatically lowered by 30.4 kJ/mol compared to undoped MgH₂. The enhanced performance of the MgH₂–CoTiO₃ system is believed to be due to the in situ formation of MgTiO₃, CoMg₂, CoTi₂, and MgO during the heating process, which offer a notable impact on the behavior of MgH₂.

Due to the increasing demand on developing good insulation, several researchers have performed experimental studies to prove the effectiveness and capabilities of transformer oil. This is done by suspending nanosized solid particles in the oil (nanofluid) for transformer applications. In brief, this paper presents a compilation of research studies which is divided into three parts. Part I discuss the preparation of the nanofluid which involves different types of nanomaterials, the optimal amount of concentrations, and applicable synthesisation methods for producing stably suspended nanofluids. In Part II, the nanofluid’s performances including the electrical breakdown voltages, impulse tests, and thermal and dielectric behaviour are reviewed in depth and compared. Part III emphasizes the limitation of nanofluids. Most researchers have agreed that appropriate concentrations of nanomaterials and the preparation method for nanofluids mainly affect the performance of nanofluids especially in terms of electrical properties. Meanwhile, types of nanomaterials and base oil also play a vital role in producing nanofluids as a better alternative transformer oil. However, among a few researchers, there are concerns regarding the issue of agglomeration and inconsistencies of findings that need to be resolved. Therefore, a few aspects must be taken into consideration to produce the next generation of high heat dissipation insulation.

We report the dramatic effect of applied pressure and magnetic field on the layered intermetallic compound ${\mathrm{Pr}}_{0.5}{\mathrm{Y}}_{0.5}{\mathrm{Mn}}_2{\mathrm{Ge}}_2$. In the absence of pressure or magnetic field this compound displays interplanar ferromagnetism at room temperature and undergoes an isostructural first order magnetic transition (FOMT) to an antiferromagnetic state below 158 K, followed by another FOMT at 50 K due to the reemergence of ferromagnetism as praseodymium orders ($T_C^{\mathrm{Pr}}$). The application of a magnetic field drives these two transitions towards each other, whereas the application of pressure drives them apart. Pressure also produces a giant magnetocaloric effect such that a threefold increase of the entropy change associated with the lower FOMT (at $T_C^{\mathrm{Pr}}$) is seen under a pressure of 7.5 kbar. First principles calculations, using density functional theory, show that this remarkable magnetic behavior derives from the strong magnetoelastic coupling of the manganese layers in this compound.

The structural and magnetic properties of seven CeMn₂Ge_2-xSi_x compounds with x = 0.0–2.0 have been investigated in detail. Substitution of Ge with Si leads to a monotonic decrease of both a and c along with concomitant contraction of the unit cell volume and significant modifications of the magnetic states - a crossover from ferromagnetism at room temperature for Ge-rich compounds to antiferromagnetism for Si-rich compounds. The magnetic phase diagram has been constructed over the full range of CeMn₂Ge_2-xSi_x compositions and co-existence of ferromagnetism and antiferromagnetism has been observed in CeMn₂Ge_1.2Si_0.8, CeMn₂Ge_1.0Si_1.0 and CeMn₂Ge_0.8Si_1.2 with novel insight provided by high resolution neutron and X-ray synchrotron radiation studies. CeMn₂Ge_2-xSi_x compounds (x = 0, 0.4 and 0.8) exhibit moderate isothermal magnetic entropy accompanied with a second-order phase transition around room temperature. Analysis of critical behaviour in the vicinity of T_C^inter for CeMn₂Ge₂ compound indicates behaviour consistent with three-dimensional Heisenberg model predictions.

The common insulating oil used in oil-filled transformer applications is mineral oil. In recent years, significant attention has been paid to alternative insulating fluids such as synthetic and natural ester liquids. The natural ester liquid is considered to be the best substitute of mineral oil in future. In order to apply natural ester liquid in transformers safely, it is important to have detailed information on its dielectric properties and its performance should be proven to be comparatively at par with mineral oil. This paper mainly focuses on a comparative study of ac breakdown voltage, dielectric constant, dissipation factor (tan δ) and resistivity of five different types of natural ester liquid under a variation of temperature. The natural ester liquids used in this experiment are rice bran oil, palm oil, corn oil, sunflower oil and canola oil. Based on the results, the dielectric constant and resistivity of all types of natural ester oil decreased with the increase in temperature. However, the dissipation factor properties in this experiment increased with the increase in temperature. In general, among all types of natural ester oil, the canola-based ester oil has the best potential to replace the current transformer oil due to its good dielectric properties as shown in this paper.