We report on the synthesis, microstructure and thermal expansion studies on Ca0.5+𝑥/2Sr0.5+𝑥/2Zr4P6−2𝑥Si2𝑥O24 (𝑥 = 0.00 to 1.00) system which belongs to NZP family of low thermal expansion ceramics. The ceramics synthesized by co-precipitation method at lower calcination and the sintering temperatures were in pure NZP phase up to 𝑥 = 0.37. For 𝑥 ≥ 0.5, in addition to NZP phase, ZrSiO4 and Ca2P2O7 form as secondary phases after sintering. The bulk thermal expansion behaviour of the members of this system was studied from 30 to 850 °C. The thermal expansion coefficient increases from a negative value to a positive value with the silicon substitution in place of phosphorous and a near zero thermal expansion was observed at 𝑥 = 0.75. The amount of hysteresis between heating and cooling curves increases progressively from 𝑥 = 0.00 to 0.37 and then decreases for 𝑥 ≥ 0.37. The results were analysed on the basis of formation of the silicon based glassy phase and increase in thermal expansion anisotropy with silicon substitution.
Volume 43, 2020
Continuous Article Publishing mode
Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020
Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
Physical Sciences 2020
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