Enhanced quality factor of wollastonite (0.9Ca_0.9Mg_0.1SiO₃-0.1CaMgSi₂O₆) glass-ceramics by heat-treatment method

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>The effects of different heat-treatment methods on the microwave dielectric properties of wollastonite (0.9Ca<SUB>0.9</SUB>Mg<SUB>0.1</SUB>SiO<SUB>3</SUB>-0.1CaMgSi<SUB>2</SUB>O<SUB>6</SUB>) glass-ceramics were investigated. The glass powders were prepared by direct and step quenching. Single-phase β-wollastonite was obtained for specimens heat-treated at 900°C for 3h from glass powders prepared by step quenching, and these had a higher quality factor (<I>Qf</I>) than specimens prepared by direct quenching. To increase the degree of crystallization, the step-quenched glass powders were heat-treated in two steps, for nucleation and then crystal growth. Increasing the holding time at the nucleation temperature (<I>T</I> <SUB>n</SUB>, 725°C), lead to an increase in the degree of crystallization and in <I>Qf</I>, with a value of 72,000GHz obtained for specimens heat-treated at 725°C for 7h and crystallized at 900°C for 3h. The dependence of the dielectric constant (<I>K</I>) and of the temperature coefficient of resonant frequency (<I>TCF</I>) on the crystallization behaviour was also investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effects of quenching and heat-treatment conditions on <I>Qf</I> value were investigated. </LI> <LI> Single phase of β-wollastonite was obtained by step quenching. </LI> <LI> The <I>Qf</I> value was affected by step quenching temperature and holding time at <I>T</I> <SUB>n</SUB>. </LI> <LI> Linear relationship between <I>Qf</I> value and degree of crystallization was confirmed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>