Search

Abstract Polyamorphic transition (PT) is a compelling and pivotal physical phenomenon in the field of glass and materials science. Understanding this transition is of scientific and technological significance, as it offers an important pathway for effectively tuning the structure and property of glasses. In contrast to the PT observed in conventional metallic glasses (MGs), which typically exhibit a pronounced first-order nature, herein we report a continuous PT (CPT) without first-order characteristics in high-entropy MGs (HEMGs) upon heating. This CPT behavior is featured by the continuous structural evolution at the atomic level and an increasing chemical concentration gradient with temperature, but no abrupt reduction in volume and energy. The continuous transformation is associated with the absence of local favorable structures and chemical heterogeneity caused by the high configurational entropy, which limits the distance and frequency of atomic diffusion. As a result of the CPT, numerous glass states can be generated, which provides an opportunity to understand the nature, atomic packing, formability, and properties of MGs. Moreover, this discovery highlights the implication of configurational entropy in exploring polyamorphic glasses with an identical composition but highly tunable structures and properties.

Tailpipe emissions from three heavy-duty diesel vehicles (HDDVs), complying with varying emission standards and installed with diverse aftertreatment technologies, are collected at a certified chassis dynamometer laboratory. The HDDV-emitted intermediate-volatility and semi-volatile organic compound (I/SVOC) emission and the gas-particle partitioning of the I/SVOCs are investigated. Over four thousand compounds are identified and grouped into twenty-one categories. The dominant compound groups of particulate I/SVOCs are alkanes and phenolic compounds. For HDDVs without aftertreatment devices, i.e., diesel oxidation catalyst (DOC) and diesel particulate filter (DPF), the emitted I/SVOCs partition dramatically into the gas phase (accounting for ~ 93% of the total I/SVOC mass), with a few exceptional categories: hopane, 4-ring polycyclic aromatic hydrocarbons (PAH4rings), and PAH5rings. For HDDVs with DPF and DOC, the particulate fractions are reduced to a negligible level, i.e., less than 2%. Nevertheless, 50% of the total 2-ring PAH mass is detected in the particle phase, which is much higher than the high-molecular-weight PAHs, arising from the positive sampling artifact of quartz filter absorbing organic vapours. The positive sampling artifact of quartz filter absorbing organic vapours is clearly observed and uncertainties are discussed and quantified. Particulate I/SVOCs at low-speed, middle-speed, and high-speed phases are collected and analysed separately. EF distribution of the speciated OA on a two-dimensional volatility basis set (2D-VBS) space reveals that the fractions of OA with O:C (oxygen to carbon) ratio > 0.3 (0.4, 0.5) are 18.2% (11.5%, 9.5%), 23% (15.4%, 13.6%), and 29.1% (20.6%, 19.1%) at low-speed, middle-speed, and high-speed stages. The results help to resolve the complex organic mixtures and trace the evolution of OA. [ABSTRACT FROM AUTHOR]