碱土替换铝硅酸盐玻璃硬度和玻璃转变温度反向演化的结构起源

Atomic-Scale Structural Origin of Reverse Relationship Between Hardness and Glass Transition Temperature of Peraluminous Aluminosilicate Glasses with Alkaline Earth Ions

为探究过铝区碱土铝硅酸盐玻璃随碱土离子替换硬度(HV)和玻璃转变温度(Tg)的演化规律及结构起源,采用激光加热气动悬浮技术,制备了摩尔组成为x RO·(49-x)Al_(2)O_(3)·51SiO_(2)(x=0~16;R=Mg,Ca,Sr,Ba)的系列碱土铝硅酸盐玻璃样品。采用显微维氏硬度仪、差示扫描量热法(DSC)分别对样品的维氏硬度(HV)和玻璃转变温度(Tg)进行了表征。结果表明:RO含量固定,随着R^(2+)场强变大,玻璃的HV升高,Tg下降;RO种类固定,随着RO对Al_(2)O_(3)替换量的增加,玻璃的HV和Tg均下降,49Al_(2)O_(3)·51SiO_(2)玻璃具有最高的HV(8.26 GPa)和最高的Tg(941℃)。结构解析发现:玻璃网络骨架的堆积密度、平均键能、键能密度以及作为电荷平衡体的填隙离子对玻璃HV和Tg提升或削弱的相互竞争和协同作用,是玻璃的HV和Tg随R^(2+)的场强变化呈现反向演化、随RO对Al_(2)O_(3)替换呈现同向演化的结构根源。

To investigate the atomic-scale structural origin of the Vickers hardness(HV)and glass transition temperature(Tg)of peraluminous aluminosilicate glasses with alkaline earth ions,we prepared a series of x RO·(49-x)Al_(2)O_(3)·51SiO_(2)(x=0.0-16.0,in mole fraction;R=Mg,Ca,Sr,Ba)alkaline earth aluminosilicate glassy samples.HV and Tg were characterized by Vickers micro-hardness test and differential scanning calorimetry(DSC).The results show that HV increases,while Tg decreases with the increase of R^(2+)field strength at a fixed RO content.At a certain type of RO,HV and Tg decrease simultaneously with the gradual substitution of Al_(2)O_(3) by RO.49Al_(2)O_(3)·51SiO_(2) glass has the maximum HV(i.e.,8.26 GPa)and Tg(i.e.,941℃).According to the structural analysis,the interactions between the competition and synergism among the packing density,average bond energy,bond energy density of glass network skeleton ions and the interstitial ions as a charge balancer are a main atomic-scale structural origin,thus leading to the reverse evolution of HV and Tg with the increase of field strength of substituted R^(2+)and the similar change with the substitution of RO for Al_(2)O_(3) in peraluminous aluminosilicate glasses.