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<p>We have successfully prepared densified glass ceramics of ZnO-B<sub>2</sub>O<sub>3</sub>-P<sub>2</sub>O<sub>5</sub> ternaries via externally nucleated crystallization of glass powder compacts, investigated crystallization, phase assemblage, morphologies, and microwave dielectric properties of the obtained glass ceramics. The glass transition temperatures (T<sub>g</sub>) are within ~ 480 and 510°C for all compositions. All glasses except the 30ZnO-10B<sub>2</sub>O<sub>3</sub>-60P<sub>2</sub>O<sub>5</sub> composition crystallize after annealing at some temperatures above the <i>T</i><sub><i>g</i></sub>. BPO<sub>4</sub>, Zn<sub>3</sub>(PO<sub>4</sub>)<sub>2,</sub> and Zn<sub>2</sub>P<sub>2</sub>O<sub>7</sub> phases crystallize sequentially with increasing annealing temperature. An additional trace amount of B exists as the annealing temperature is over 700°C due to the incongruent evaporation of BPO<sub>4</sub>. An increase in ZnO and a decrease in B<sub>2</sub>O<sub>3</sub> without much change in the P<sub>2</sub>O<sub>5</sub> content of the glass composition results in reducing the crystallization temperatures. The crystallization activation energies of the α-Zn<sub>2</sub>P<sub>2</sub>O<sub>7</sub> in the 30ZnO-40B<sub>2</sub>O<sub>3</sub>-30P<sub>2</sub>O<sub>5</sub>, 40ZnO-60BPO<sub>4</sub>, and Zn<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> in the 60ZnO-10B<sub>2</sub>O<sub>3</sub>-30P<sub>2</sub>O<sub>5</sub> glasses were estimated to be ~ 211–197, ~ 189–199, ~ 96–108 kJ/mol, respectively, by both Kissinger and Qzawa methods. The crystallization of BPO<sub>4</sub>, Zn<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>, and α-Zn<sub>2</sub>P<sub>2</sub>O<sub>7</sub> phases would increase the <i>ε</i><sub><i>r</i></sub>,<i> Q</i> × <i>f</i> value, and negative value of <i>τ</i><sub><i>f</i></sub>. The 60ZnO-10B<sub>2</sub>O<sub>3</sub>-30P<sub>2</sub>O<sub>5</sub> glass ceramic annealed at 875°C/2h has good combined microwave dielectric properties with <i>ε</i><sub><i>r</i></sub> ~ 5.60, <i>Q</i> × <i>f</i> ~ 51,989 GHz, <i>τ</i><sub><i>f</i></sub> ~ -99.4 ppm/<sup>o</sup>C.</p>

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Crystallization and microwave dielectric properties of ZnO-B2O3-P2O5 glass ceramics

  • 期刊论文

  • 发表日期：

    2025年11月21日

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  • H. J. Wang,
  • J. J. Bian

摘要

We have successfully prepared densified glass ceramics of ZnO-B2O3-P2O5 ternaries via externally nucleated crystallization of glass powder compacts, investigated crystallization, phase assemblage, morphologies, and microwave dielectric properties of the obtained glass ceramics. The glass transition temperatures (Tg) are within ~ 480 and 510°C for all compositions. All glasses except the 30ZnO-10B2O3-60P2O5 composition crystallize after annealing at some temperatures above the Tg. BPO4, Zn3(PO4)2, and Zn2P2O7 phases crystallize sequentially with increasing annealing temperature. An additional trace amount of B exists as the annealing temperature is over 700°C due to the incongruent evaporation of BPO4. An increase in ZnO and a decrease in B2O3 without much change in the P2O5 content of the glass composition results in reducing the crystallization temperatures. The crystallization activation energies of the α-Zn2P2O7 in the 30ZnO-40B2O3-30P2O5, 40ZnO-60BPO4, and Zn3(PO4)2 in the 60ZnO-10B2O3-30P2O5 glasses were estimated to be ~ 211–197, ~ 189–199, ~ 96–108 kJ/mol, respectively, by both Kissinger and Qzawa methods. The crystallization of BPO4, Zn3(PO4)2, and α-Zn2P2O7 phases would increase the εr, Q × f value, and negative value of τf. The 60ZnO-10B2O3-30P2O5 glass ceramic annealed at 875°C/2h has good combined microwave dielectric properties with εr ~ 5.60, Q × f ~ 51,989 GHz, τf ~ -99.4 ppm/oC.