Chemical properties of aluminum nitride crystals

在标准大气压下，AlN晶体在1700℃左右开始缓慢分解成Al蒸气和氮气，当温度达到2200℃时AlN迅速分解成Al蒸气和氮气，在不同温度下AlN分解后的分压如图3所示。常压下AlN晶体很难以液相形式存在，在AlN达到熔点之前AlN已经开始分解，这是AlN晶体不能通过熔融法生长的原因，但有研究表明，100大气压下AlN液相可在2800℃出现。AlN粉末在空气中很不稳定，容易与空气中的水蒸气和氧气反应生成氨气和氧化铝。AlN具有很强的抗酸碱能力，酸性环境中AlN可以稳定存在，在碱性环境中AlN少量被腐蚀。300℃时，AlN晶体在KOH和NaOH的1:1熔液中腐蚀3-5min，晶体表面可以观察到六方腐蚀坑等缺陷，但除此之外，未见大量腐蚀的迹象，实验上通过此方法区分AlN的极性面。

At standard atmospheric pressure, AlN crystals begin to decompose slowly into Al vapor and nitrogen at about 1700 degrees. When temperature reaches 2200 degrees, AlN decomposes rapidly into Al vapor and nitrogen. The partial pressure of AlN decomposition at different temperatures is shown in Figure 3. Under normal pressure, AlN crystal is very difficult to exist in liquid phase. Before AlN reaches the melting point, AlN has begun to decompose, which is why AlN crystals can not grow by melting. However, studies have shown that the AlN liquid phase can appear at 2800 AlN at atmospheric pressure. AlN powder is very unstable in the air, and it is easy to react with the water vapor and oxygen in the air to produce ammonia and alumina. AlN has a strong ability to resist acid and alkali, and AlN can be stable in acid environment. In alkaline environment, a small amount of AlN is corroded. At 300 C, AlN crystals corrode 3-5min in the 1:1 melt of KOH and NaOH. Defects such as six party corrosion pits can be observed on the surface of the crystal, but there is not a lot of corrosion. Besides, the polar surface of AlN is distinguished by this method.