Glasses with Fictive Temperature-Independent Properties

非技术描述：一般来说，玻璃的性质取决于它从熔体中冷却的速度。有两种不同类型的玻璃：正常玻璃和反常玻璃，它们表现出相反的冷却速率依赖性的性质。因此，在这两类具有相反趋势的玻璃之间，应该存在一些性质不随冷却速率变化的特殊玻璃。预计这些玻璃在许多应用中是有用的。例如，由这种玻璃制成的平板显示屏在热处理期间不会改变其体积，并且电极可以放置在精确的位置，从而在屏幕上产生更清晰的图像。当玻璃被硬物划伤时，玻璃的一部分似乎改变了其结构和性质，这可能导致容易破裂。在这项研究中要研究的特殊玻璃似乎在刮擦过程中不会改变其特性，因此不太可能破裂。一名研究生和两名本科生将在这个计划中接受培训。三名学生中至少有一名是女性。技术参数：在不同冷却速率下制备的玻璃根据其假想温度来定义，即，液体冻结成玻璃态的温度。具有假想的温度无关性质的玻璃预期表现出在实际应用中有用的独特特性，例如在液晶显示器玻璃加工过程中的非压实性。金刚石压痕常用于表征玻璃的机械性能，但压痕过程中发生的情况尚不清楚。看来，虚拟温度的玻璃压痕过程中增加和虚拟温度依赖性的玻璃性能压痕下的机械行为起着重要的作用。因此，对所提出的玻璃的这项研究预计将导致具有独特性能的玻璃的开发，并澄清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.