It was decided that the year of 2022 would be the International Glass Year, at the United Nations General Assembly in May 2021. In this special issue, we present the past and recent situation of the study of the Glass and recognize the contribution of glass to our life and industry, and the future.

Glass not only attracts people beautifully, but has been an important material for many technologies since ancient times, and will continue to be an important material that supports a sustainable future society. This report introduces how glass is used and its functions in daily life and industry, including surface treatment and coating of glass.

In 2020, the Japanese government has announced to achieve “Carbon Neutral” with ZERO emission of greenhouse effect gas in total by 2050. The SDGs activity in all over the world has been conducting and the activity to build-up for decarbonized society in the industrial world has become active recently. Under such circumstance, as energy saving of the buildings to reduce CO₂ emission, the need of the high insulation performance for the window with remarkable heat transfer in building has been getting higher.

Vacuum Glazing has a high insulation performance for the window in the building and is strong effective for energy saving of it. This report will be introduced the heat transfer mechanism in vacuum layer and characteristic performance of vacuum glazing.

Room-temperature wafer bonding can realize new electronic devices, power devices, optical devices, and microelectromechanical systems. Atomic diffusion bonding (ADB) of wafers is a promising process to achieve room-temperature wafer bonding : thin metal films are fabricated on two flat wafer surfaces using sputter deposition, followed by bonding of the two films on the wafers in vacuum. Any mirror-polished wafer including glass can be bonded using ADB. Recently we demonstrated ADB of wafers at room temperature using oxide films and nitride films. Incident light can pass through transparent wafers bonded with oxide films without reduction in intensity. Moreover, the electrical conductivity of the bonded oxide films and nitride films is negligible. These properties are useful to produce new optical or electrical devices. This paper assesses the technical potential and current status of ADB.

Thermoresponsive switchable window glasses were developed with meso- (submicron- to micron-) scale composites of orientation-co-ordered liquid crystals (LCs) and reactive mesogens (RMs). These structures are called polymer network liquid crystals (PNLCs). These were produced through a simple self-assembly process or photopolymerization induced phase separation (PPIPS), conducted by ultraviolet irradiation. Transparent and hazy states thermoresponsively change, caused by nematic-to-isotropic phase transition. This switchability changes backscattering intensity and consequently controls hemispherical transmittance as well as optical clarity. The PNLCs have practical applications to energy-saving smart windows because of their simple fabrication process, adaptability, and durability.

The structural study of glassy materials remains still a challenging scientific topic owing to the lack of distinct translational periodicity. However, a combination of the advent of quantum (synchrotron X-ray/neutron) beam instrumentation and data-driven structural modelling assisted by advanced computational/mathematical techniques enables us to probe the order within disorder in glassy materials. In particular, it is possible to reveal the structure beyond the nearest-neighbour distance by structural modelling. In this article, we focus on structural studies of oxide glasses and liquids by quantum beam diffraction and data-driven structural modelling.

On 18th May 2021, the United Nations General Council approved that 2022 be declared a “International Year of Glass 2022”. The long history of glass shows us contribution of glass to the human society, especially at turning points of human life, science and technology. In contrast, recent investigations of glasses suggest unlimited potential of glass. In this paper, we will introduce the new vitrification method using the aerodynamic levitation furnace, as one of potentials of the conventional and novel materials “glass”. This method is able to produce the non-conventional glasses which do not include glass-formers such as SiO₂. Furthermore, these glasses indicated excellent optical and mechanical properties. However, some issues to overcome are remained in the viewpoint not only of chemical compositions but of improvements regarding the gas flow and the laser heating. We hope that the glass world will expand beyond the boundary of research fields in the future.

The intermediate flow in the vacuum pipe is calculated by Monte Carlo simulation using a new concept that takes into account the influence of the flow rate and the beam effect. The obtained transmission probabilities of gas molecule through the pipe are in good agreement with the experimental values and Hanks's low. The resulting molecular density distribution in the pipe indicates that there are twice conductance of the orifice conductance on both ends of the pipe. The conductance of a long pipe is discussed in comparison with Knudsen's equation.