研究目的
To study the dielectric responses in the terahertz range of the donor-acceptor substituted ZnTiNb2O8 system, focusing on the effects of Nb5+ and Al3+ substitution on Ti4+, and to determine the origins of lower dielectric loss and terahertz wave absorption coefficient.
研究成果
The research demonstrates that donor-acceptor substitution in ZnTiNb2O8 ceramics reduces dielectric loss and terahertz absorption, attributed to high chemical bond covalency and phase control. The optimal composition (x=0.15, sintered at 1180°C) shows promising properties for terahertz dielectric devices. Future studies could focus on further improving temperature stability and exploring other material systems.
研究不足
The study is limited to the specific ZnTiNb2O8 system with donor-acceptor substitution; potential limitations include the formation of secondary phases at high substitution levels and sintering temperatures, which may affect material properties. Optimization could involve exploring other substitution elements or sintering conditions.
1：Experimental Design and Method Selection:
The study uses a solid-state reaction method to synthesize ZnTi1-x(Al
2：5Nb5)xNb2O8 ceramics, with x ranging from 0 to Theoretical models include ligand field theory, P-V-L chemical bond theory, and Rietveld refinement for crystal structure analysis. Sample Selection and Data Sources:
High-purity ZnO, Nb2O5, Al2O3, and TiO2 powders (>
3：9%) are used as raw materials. Samples are calcined and sintered at temperatures from 1100 to 1220°C. List of Experimental Equipment and Materials:
Equipment includes XRD (Rigaku D/MAX-2500), FESEM (FEI Nanosem 430), network analyzer (Agilent 8720ES), and terahertz time-domain spectroscopy (Advantest TAS7500TS). Materials include zirconia milling media and deionized water.
4：Experimental Procedures and Operational Workflow:
Powders are mixed, calcined at 950°C, pressed into pellets, and sintered. Density is measured by Archimedes method. XRD, SEM, and dielectric measurements are performed.
5：Data Analysis Methods:
Rietveld refinement for XRD data, P-V-L theory for bond covalency calculations, and equations for dielectric properties in microwave and terahertz ranges.
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