A. Feteira , G.M. Keith , M.J. Rampling , C.A. Kirk , I.M. Reaney , K. Sarma , N. Mc. Alford , D.C. Sinclair
{"title":"Synthesis and characterisation of Ga-doped hexagonal BaTiO3","authors":"A. Feteira , G.M. Keith , M.J. Rampling , C.A. Kirk , I.M. Reaney , K. Sarma , N. Mc. Alford , D.C. Sinclair","doi":"10.1016/S1463-0184(02)00055-2","DOIUrl":null,"url":null,"abstract":"<div><p>The hexagonal polymorph of BaTiO<sub>3</sub> (P6<sub>3</sub>/mmc) has been stablished at room temperature by partial replacement of Ti by Ga, where BaTi<sub>1-y</sub>Ga<sub>y</sub>O<sub>3-y/2</sub> and 0.06≤<em>y</em><span>≤0.125 for samples prepared at 1300°C. The unit cell expands with increasing y and Rietveld Refinement of Neutron diffraction data shows that oxygen vacancies occur only in the hexagonal close packed layers between the face-sharing Ti</span><sub>2</sub>O<sub>9</sub> dimers. Exaggerated grain growth (>100 μm) occurs for ceramics processed at ≥1400°C and/or for sintering periods ≥2 hours. Electrical measurements show the materials to be electrically insulating with room temperature permittivity values of ~70–80. Dense ceramics (94–97% of the theoretical X-ray density) resonate at microwave frequencies with Q.f values of ~4000–8000 at ~5.5 GHz.</p></div>","PeriodicalId":10766,"journal":{"name":"Crystal Engineering","volume":"5 3","pages":"Pages 439-448"},"PeriodicalIF":0.0000,"publicationDate":"2002-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1463-0184(02)00055-2","citationCount":"17","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Crystal Engineering","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1463018402000552","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 17
Abstract
The hexagonal polymorph of BaTiO3 (P63/mmc) has been stablished at room temperature by partial replacement of Ti by Ga, where BaTi1-yGayO3-y/2 and 0.06≤y≤0.125 for samples prepared at 1300°C. The unit cell expands with increasing y and Rietveld Refinement of Neutron diffraction data shows that oxygen vacancies occur only in the hexagonal close packed layers between the face-sharing Ti2O9 dimers. Exaggerated grain growth (>100 μm) occurs for ceramics processed at ≥1400°C and/or for sintering periods ≥2 hours. Electrical measurements show the materials to be electrically insulating with room temperature permittivity values of ~70–80. Dense ceramics (94–97% of the theoretical X-ray density) resonate at microwave frequencies with Q.f values of ~4000–8000 at ~5.5 GHz.
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