This proposal presents a research and development strategy that redefines the spatial and temporal heterogeneities inherent in materials--such as structural disorder and time-dependent variations (hereafter collectively referred to as "disorder")--not as defects or imperfection to be eliminated, but as essential sources of novel functionalities. Advancing the understanding, control, and purposeful utilization of such heterogeneities will provide new control parameters indispensable for the creation of next-generation high-performance materials.

As global challenges such as environmental issues, energy demands, aging societies, and rapid digitalization grow increasingly complex, the limitations of conventional homogeneous and static approaches to materials design have become evident. Materials science is entering a stage in which the proactive utilization of "disorder" across various scales--previously applied only to a limited range of material systems--is being extended to many more types of materials. This report organizes this transition in a systematic manner and presents future directions for R&D.

The central concept of the proposal is to reposition "disorder" from something to be avoided to a design freedom to be deliberately exploited. Specifically, the proposal highlights three key benefits:

First, it calls for renewing the starting point of materials science from "ideal substances" to "real materials." This involves going beyond traditional theories and characterization methods that rely on averaged structures or equilibrium approximations, and instead constructing a materials physics that treats disorder--spatial non-uniformity and temporal evolution--as essential degrees of freedom. Such an approach is expected to establish a unified "science of disorder" that encompasses crystalline, amorphous, and multiphase materials.

Second, by balancing the suppression of "undesirable disorder" with the intentional design of "beneficial disorder," it becomes possible to overcome performance trade-offs that were previously considered difficult to break. Controlling grain boundaries, vacancies, strain fields, and interfacial reconstructions as design variables enables simultaneous achievement of properties such as high strength with high toughness, or high efficiency with high stability. Moreover, leveraging temporal evolution opens new possibilities for functions such as age-hardening, self-healing, and dynamic responses.

Third, by linking theory, characterization, and synthesis through data, and forming an autonomous materials discovery loop using AI and simulation, the R&D cycle can be accelerated and cost-efficient. Standardizing quantitative descriptors of disorder will enhance interoperability among experiments, computations, and AI, allowing Japan to take a leading role in establishing international standards for AI for Materials Science.

These new perspectives align with emerging research trends worldwide. In Japan, government initiatives such as the "Strategy for Strengthening Materials Innovation" and the MEXT FY2025 strategic objective, "Creation of Innovative Materials through Control and Utilization of Fluctuations," explicitly position nonequilibrium states and structural heterogeneities as national research priorities. Overseas, similar directions are seen in the U.S. Materials Genome Initiative and Europe's Advanced Materials 2030 Initiative, which emphasize the intentional design of structural and temporal heterogeneity.

This proposal, informed by such global developments, highlights the need to establish shared terminology and research foundations for addressing disorder across theory and computation, characterization and evaluation, and synthesis and manufacturing. Looking ahead to the next 30 years of materials science in Japan, a paradigm shift is essential--from static, idealized structures to research frameworks grounded in understanding and designing dynamic, nonequilibrium real materials.

In short, treating "disorder" not as a defect but as a source of functionality represents the next frontier in materials science and is directly linked to the creation of transformative functional materials and the strengthening of industrial competitiveness. This proposal presents the scientific foundations and strategic direction necessary to realize that future.

• (in Japanese) Harnessing Defects, Disorder, Inhomogeneity, Fluctuations and Evolution in Materials Science