Glasses with Fictive Temperature-Independent Properties

非技术描述：一般来说，玻璃的性能取决于它从熔体冷却的速度。有两种不同类型的玻璃：正常玻璃和异常玻璃，它们表现出相反的冷却速率依赖性质。因此，在这两种趋势相反的玻璃之间，应该存在一些性能不随冷却速率变化的特殊玻璃。这些眼镜有望在许多应用中发挥作用。例如，由这种玻璃制成的平板显示屏在热处理过程中不会改变其体积，电极可以放置在精确的位置，从而使屏幕上的图像更清晰。当玻璃被硬物划伤时，玻璃的一部分似乎会改变其结构和性能，这可能导致容易破裂。在本研究中所研究的特殊玻璃在刮擦过程中似乎不会改变其性能，因此不太可能破裂。该项目将培养一名研究生和两名本科生。三名学生中至少有一名是女性。技术细节：在不同冷却速率下制备的玻璃是根据其有效温度来定义的，即液体冻结成玻璃态的温度。具有有效温度无关特性的玻璃有望在实际应用中表现出独特的特性，例如液晶显示玻璃加工过程中的不压实。金刚石压痕常被用来表征玻璃的力学性能，但压痕过程中发生了什么尚不清楚。结果表明，压痕过程中玻璃的实际温度升高，玻璃性能的实际温度依赖性对压痕力学行为起着重要作用。因此，对所提出的玻璃的研究有望导致具有独特性能的玻璃的发展，并阐明在玻璃和其他脆性材料的压痕过程中发生了什么。

NON-TECHNICAL DESCRIPTION: In general, properties of a glass vary depending upon how fast it was cooled from its melt. There are two different types of glasses: normal glass and anomalous glass and they exhibit the opposite cooling rate dependences of properties. Thus, between these two types of glasses with opposite trends, there should be some special glasses whose properties do not change with cooling rate. These glasses are expected to be useful in many applications. For example, a flat panel display screen made of such glasses would not change its volume during the heat-treatment and electrodes can be placed at precise positions, leading to clearer images on the screen. When a glass is scratched with a hard object, a portion of the glass appears to change its structure and properties, which can lead to easy cracking. The special glass to be investigated in this research appears not to change its properties during scratching and is consequently less likely to crack. One graduate student and two undergraduate students will be trained in this program. At least one of the three students will be female.TECHNICAL DETAILS: Glass prepared under different cooling rates is defined in terms of its fictive temperature, i.e., the temperature at which the liquid freezes into the glassy state. Glasses with fictive temperature-independent properties are expected to exhibit unique characteristics useful in practical application such as non-compaction during liquid crystal display glass processing. Diamond indentation is often used to characterize mechanical properties of glasses, but what is happening during indentation is not clear. It appears that fictive temperature of a glass increases during indentation and the fictive temperature dependence of glass properties plays an important role in mechanical behavior under indentation. Thus, this study of the proposed glasses is expected to lead to the development of glasses with unique properties and clarify what is occurring during indentation in glasses and other brittle materials.