Microstructure and phase evolution of polymer‐derived SiHfOC ceramic microspheres

Abstract

The SiHfOC ceramic microspheres were synthesized from the polysilazane and hafnium(IV) acetylacetonate hybrid precursors through a combination of hydrothermal method and polymer-derived ceramics (PDCs) method. The SiHfOC ceramic microspheres consist of β-SiC, SiO 2 , and m-HfO 2 in an amorphous SiOC matrix and are in a spherical morphology with an average size of about 2 μm. Hafnium-containing nanoparticles with ∼50-nm size are not only uniformly distributed on the surface of the ceramic microspheres but also embedded in the SiHfOC ceramic microspheres, forming a unique mosaic structure. Pyrolyzing at 1000 • C offers a possibility of an in situ formation of nanocrystal nuclei in the amorphous SiOC ceramic matrix, and the subsequent annealing at 1500 • C helps the small nanocrystal nuclei grow and separate the amorphous SiHfOC into a multiphase SiOC network containing β-SiC, SiO 2 , m-HfO 2 nanocrystalline and free C. This research provides a methodology for preparing multicomponent ceramic microspheres that can efficiently develop high-performance PDCs modified by transition metal alkoxide.

Toward Ecofriendly Piezoelectric Ceramics—Reduction of Energy and Environmental Footprint from Conceptualization to Deployment

“…[75][76][77][78][79][80] The BNT-BKT ((Bi 0.5 K 0.5 )TiO 3 ) binary system and its family can produce d 33 values in the range of 130-230 pC N −1 . [81][82][83][84][85] Other perovskite solid solutions such as KNN and SrTiO 3 may also form binary systems with the BNT and even ternary systems with the BNT-BT or BNT-BKT to construct the MPB-I at room temperature. These systems are able to produce d 33 values in the range of 150-235 pC N −1 .…”

Investigation on the Correlation between Piezoelectricity and Its Thermal Behavior with Depolarization Temperature and Antiferroelectric Order in Niobium‐Doped (Na0.41K0.09Bi0.5)TiO3: A Lead‐Free Piezoelectric

“…[ 18–25 ] Despite several significant efforts, the best reported k p and d 33 values for the doped [Bi 0.5 Na 0.41 K 0.09 ]TiO 3 are 0.29 and 150 pC N −1 , respectively. On the contrary, Zhang et al [ 26 ] achieved the similar values for the piezoelectric coefficients in pure [Bi 0.5 Na 0.41 K 0.09 ]TiO 3 by optimizing the material synthesis process.…”