菱镁矿法合成微纳米三水碳酸镁晶须的研究

通过菱镁矿法合成了微纳米MgCO3·3H2O晶须.利用XRD，SEM研究了不同产地的原料、热解温度和添加剂种类对产物组成和形貌的影响.结果表明:最佳热解温度为50℃，采用宽甸和岫岩菱镁矿均能合成出结晶良好、高长径比的棒状MgCO3·3H2O晶须；当热解温度超过50℃时，MgCO3·3H2O晶须不稳定.SEM分析表明，无添加剂时，热解产物为不规则的棒状和针状混合晶体；添加无水乙醇和十二烷基硫酸钠时，产物均为表面光滑、长径比大的棒状晶体；添加多聚磷酸钠时，产物为团聚生长的短粗棒状晶体.菱镁矿法的实质是以菱镁矿为原料，经煅烧、水化和碳酸化反应后制得Mg(HCO3)2前驱溶液，再热解Mg(HCO3)2溶液得到最终产物MgCO3·3H2O晶须.

Synthesis of Micro/Nano Nesquehonite Whiskers with Magnesite Method

Micro/nano nesquehonite whiskers were synthesized with magnesite method. The effects of raw materials from different regions， pyrolysis temperatures and types of additive on phase compositions and morphology of products were respectively investigated by means of XRD and SEM. The results showed that well crystallized rod like nesquehonite whiskers with high aspect ratio can be synthesized at the optimal pyrolysis temperature of 50 ℃， using magnesite from Kuandian and Xiuyan as raw materials. Nesquehonite whiskers become unstable when the pyrolysis temperature is over 50 ℃. The results of SEM analysis showed that pyrolysis products obtained are irregular rod like and acicular mixed crystal without any additive. Smooth rod like crystals with high aspect ratio were obtained with additive of absolute alcohol and sodium dodecyl sulfate. Stubby aggregates were obtained with additive of sodium polyphosphate. The essence of magnesite method was that Mg(HCO3)2 precursor solution was prepared by calcination， hydration and carbonation treatment using magnesite as raw material， then nesquehonite crystals could be synthesized through the pyrolysis of Mg(HCO3)2 solution.