Effects of sintering method and BiFeO3 dopant on the dielectric and ferroelectric properties of BaTiO3–BiYbO3 based solid solution ceramics

(0.95–x) BaTiO₃–0.05 BiYbO₃–x BiFeO₃ (x?=?0, 0.01, 0.02, and 0.04) (abbreviated as (0.95–x) BT–0.05 BY–x BFO) ceramics were fabricated by conventional sintering (CS) and microwave sintering (WS) methods. Effects of sintering method and BFO dopant on the microstructure and electric properties of (0.95–x) BT–0.05 BY–x BFO ceramics were comparatively investigated. X-ray diffraction showed that all CS and WS samples presented a single perovskite phase. It was also found that WS ceramics possessed denser microstructure and finer grains compared to CS samples as indicated by the surface morphology characterization. Dielectric measurements revealed that all samples exhibited the weak relaxation behavior; however, the degree of relaxation behavior of BT–BY based ceramic could be strengthened by addition of BFO and by WS method. Moreover, the temperature and frequency stability could be improved with doped BFO. The density of 0.93BT–0.05BY–0.02BFO ceramic was found to be the largest while that of 0.94BT–0.05BY–0.01BFO ceramic was the smallest, thus, the dielectric constant of 0.93BT–0.05BY–0.02BFO was significantly larger than that of 0.94BT–0.05BY–0.01BFO and 0.94BT–0.05BY–0.04 BFO ceramics. minimum dielectric constant of (0.95–x) BT–0.05 BY–x BFO ceramic was obtained at x?=?0.01. Ferroelectric measurements indicated that all samples showed the slim hysteresis loop. The remnant polarization (P_r) and coercive field (E_C) of (0.95–x) BT–0.05 BY–x BFO ceramics first decreased and then increased with increasing x，the minimum values were obtained at x?=?0.01. Moreover, P_r and E_C of WS ceramics were slightly larger than those of CS ceramics, indicating that higher density and larger grain sizes contributed to enhancing the ferroelectric characteristic. These findings indicate that addition of moderate amount of BFO and use of WS technique can strengthen the degree of relaxation behavior and improve the ferroelectric properties of BT–BY based ceramics.     

城市发展的经济成本分析——以重庆市为例

经济的发展是城市发展最根本的活力源泉,对城市发展进行经济论证应该成为城市规划的最基本的依据之一.文中论述了城市化经济成本的内涵、类型和构成,依据目前的经济、社会发展水平,从狭义和广义两种尺度上对重庆市的城市化经济成本进行了调研测算;在此基础上,从城市化发展的经济带动能力来预测重庆市未来的城市化水平,并根据城市化经济成本预测未来城市发展的资金需求.     

重庆都市区土地资源可持续利用对策

重庆都市区位于长江三峡水库生态环境脆弱的库尾区域，经济的快速发展已对有限的土地资源产生了较大的影响。通过对都市区土地资源的可持续利用的初步研究，分析了土地资源可持续利用中存在的5个主要问题，提出了实现都市区土地资源可持续利用6项措施。     

重庆城市轨道交通发展探讨

确立以轨道交通为重点的城市交通发展战略是重庆城市交通的必然选择。阐述了发展城市轨道交通的问题及其对城市结构的影响，分析了重庆的实际情况以及轨道交通的现状，提出了重庆市轨道交通发展的思路和方向。     

在大开发中实现重庆产业结构和布局的再构建

产业结构和地区布局的构建是地区经济发展的首要问题 ,为此从重庆产业结构调整和配置入手 ,在深入分析重庆现有产业结构和布局中存在的四大矛盾的基础上 ,着重分析重庆产业结构和产业布局再构建的可能性 ,提出了有益于重庆产业结构和产业布局调整的、有创见性的构想。     

提升重庆市旅游经济素质的途径探讨

加入WTO ,重庆旅游业面对巨大的挑战 ,重庆旅游业只有拿出世界级的经济素质 ,在重庆创造出世界级旅游产品 ,才能立于不败之地。重庆旅游业在经济素质方面存在诸多问题 ,笔者从提高重庆旅游经济素质的角度 ,对重庆旅游业应采取何种对策、如何实施这些对策进行了论述。     

构建重庆三峡库区生态经济区的设想

三峡库区生态经济区是重庆市确立的三大经济区之一,是重庆市经济社会可持续发展的重要保证。库区生态经济区应实施“加快发展提升．发挥后发优势”的发展战略,依托渝万高速公路和长江黄金水道、渝怀铁路和319国道两条轴线和万州、涪陵、黔江、长寿4个地区性中心城市,构建生态经济区,重点发展高效生态农业、生态城镇、生态工业和生态旅游业四大产业。     

重庆白云湖旅游开发区规划设计研究

通过对重庆白云湖旅游开发区总体方案及主要景区的分析介绍,指出建筑环境的创作应充分体现传统文化,并应与地方的自然环境紧密结合。它是进行有建筑特色创作的基础,也符合中国传统建筑所提倡的“天人合一”的建筑理念。     

重庆市污水源热泵应用前景分析

文章介绍了城市污水的主要热特性以及污水源热泵的优势，结合重庆市的污水排放情况，分析了在重庆市运用污水源热泵的方案，并简要分析了在重庆市采用污水源热泵所产生的效益，最后得出污水源热泵在重庆市具有良好的应用前景的结论。     

对重庆市人力资源开发的现状、问题的思考

分析了重庆市人力资源开发现状与制约因素，提出重庆市人力资源开发的战略对策：创新观念，树立正确的人力资源观；创新机制；优先发展教育，合理布局教育资源；努力增加就业机会，实现充分就业；完善人力资源市场配置功能，引导人力资源合理流动；重视农村人力资源开发，推动农村剩余劳动力的转移；发挥政府在人力资源开发中的作用；构筑终身教育体系，创建学习型社会；优化人力资源开发的环境。