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在制备Cd_xHg_(1-x)Te晶体的铸造—再结晶—退火工艺中,最重要的一步是快速淬火,以便形成细小晶粒的多晶锭,然后进行高温退火促进晶粒生长。在铸造阶段控制热散失是决定最终晶体结构的关键。为了模拟铸造时的热流,作了电模拟,并用计算机分析。模型给出热流、温度分布(等温线)和冷却速率。模拟了石英安瓿对辐射的部分透明性。在强制冷却安瓿底部时,给出了晶体/熔体的热导率、气体的热导率和铸造速率的变化对冷却速率和等温线形状的影响。把从模型中获得的等温线与在铸造锭上看到的枝蔓晶结构作了比较,发现理论和实验很一致。
The most important step in the casting-recrystallization-annealing process for the preparation of Cd_xHg_ (1-x) Te crystals is rapid quenching to form multi-crystalline ingots of fine grains followed by high-temperature annealing to promote grain growth. Controlling heat loss at the casting stage is the key to determining the final crystal structure. In order to simulate the heat flow during casting, an electrical simulation was made and analyzed by computer. The model gives the heat flow, temperature distribution (isotherm) and cooling rate. The partial transparency of the quartz ampoules to radiation was simulated. The effect of crystal / melt thermal conductivity, gas thermal conductivity and casting rate on the cooling rate and isotherm shape is given when forced cooling of the bottom of the ampoule. Comparing the isotherm obtained from the model with the dendrite structure seen on the cast ingot, we found that the theory and experiment are consistent.